Quad Input, Five-Output, Dual DPLL
Synchronizer and Adaptive Clock Translator
Data Sheet
AD9542
Rev. 0 Document Feedback
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FEATURES
Dual DPLL synchronizes 2 kHz to 750 MHz physical layer
clocks providing frequency translation with jitter cleaning
of noisy references
Complies with ITU-T G.8262 and Telcordia GR-253
Supports Telcordia GR-1244, ITU-T G.812, G.813, G.823,
G.824, and G.825
Continuous frequency monitoring and reference validation
for frequency deviation as low as 50 ppb
Both DPLLs feature a 24-bit fractional divider with 24-bit
programmable modulus
Programmable digital loop filter bandwidth: 10−4 Hz to 1850 Hz
Automatic and manual holdover and reference switchover,
providing zero delay, hitless, or phase buildout operation
Programmable priority-based reference switching with
manual, automatic revertive, and automatic nonrevertive
modes supported
5 pairs of clock output pins with each pair useable as
differential LVDS/HCSL/CML or as 2 single-ended outputs
(1 Hz to 500 MHz)
2 differential or 4 single-ended input references
Crosspoint mux interconnects reference inputs to PLLs
Supports embedded (modulated) input/output clock signals
Fast DPLL locking modes
Provides internal capability to combine the low phase noise
of a crystal resonator or crystal oscillator with the
frequency stability and accuracy of a TCXO or OCXO
External EEPROM support for autonomous initialization
Single 1.8 V power supply operation with internal regulation
Built in temperature monitor/alarm and temperature
compensation for enhanced zero delay performance
APPLICATIONS
SyncE jitter cleanup and synchronization
Optical transport networks (OTN), SDH, and macro and small
cell base stations
OTN mapping/demapping with jitter cleaning
Small base station clocking, including baseband and radio
Stratum 2, Stratum 3e, and Stratum 3 holdover, jitter
cleanup, and phase transient control
JESD204B support for analog-to-digital converter (ADC) and
digital-to-analog converter (DAC) clocking
Cable infrastructures
Carrier Ethernet
GENERAL DESCRIPTION
The 10 clock outputs of the AD9542 are synchronized to any
one of up to four input references. The digital phase-locked
loops (DPLLs) reduce timing jitter associated with the external
references. The digitally controlled loop and holdover circuitry
continuously generate a low jitter output signal, even when all
reference inputs fail.
The AD9542 is available in a 48-lead LFCSP (7 mm × 7 mm)
package and operates over the −40°C to +85°C temperature
range.
Note that throughout this data sheet, multifunction pins, such
as SDO/M5, are referred to either by the entire pin name or by a
single function of the pin, for example, M5, when only that
function is relevant.
AD9542 Data Sheet
Rev. 0 | Page 2 of 61
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 3
Functional Block Diagram .............................................................. 4
Specifications ..................................................................................... 5
Supply Voltage ............................................................................... 5
Supply Current .............................................................................. 5
Power Dissipation ......................................................................... 5
System Clock Inputs, XOA and XOB ......................................... 6
Reference Inputs ........................................................................... 7
Reference Monitors ...................................................................... 8
DPLL Phase Characteristics ........................................................ 8
Distribution Clock Outputs ........................................................ 9
Time Duration of Digital Functions ........................................ 10
Digital PLL (DPLL0, DPLL1) Specifications .......................... 10
Digital PLL Lock Detection Specifications ............................. 11
Holdover Specifications ............................................................. 11
Analog PLL (APLL0, APLL1) Specifications .......................... 11
Output Channel Divider Specifications .................................. 11
System Clock Compensation Specifications ........................... 12
Temperature Sensor Specifications .......................................... 12
Serial Port Specifications ........................................................... 12
Logic Input Specifications (RESETB, M0 to M6) .................. 14
Logic Output Specifications (M0 to M6) ................................ 14
Jitter Generation (Random Jitter) ............................................ 14
Phase Noise ................................................................................. 15
Absolute Maximum Ratings .......................................................... 18
Thermal Resistance .................................................................... 18
ESD Caution ................................................................................ 18
Pin Configuration and Function Descriptions ........................... 19
Typical Performance Characteristics ........................................... 21
Terminology .................................................................................... 25
Theory of Operation ...................................................................... 26
Overview ...................................................................................... 26
Reference Input Physical Connections .................................... 26
Input/Output Termination Recommendations .......................... 27
System Clock Inputs ................................................................... 27
Reference Clock Inputs .............................................................. 27
Clock Outputs ............................................................................. 28
System Clock PLL ........................................................................... 29
System Clock Input Frequency Declaration ........................... 29
System Clock Source .................................................................. 29
2× Frequency Multiplier ............................................................ 29
Prescale Divider .......................................................................... 29
Feedback Divider ........................................................................ 30
System Clock PLL Output Frequency ..................................... 30
System Clock PLL Lock Detector............................................. 30
System Clock Stability Timer .................................................... 30
System Clock Input Termination Recommendations ........... 30
Digital PLL (DPLL) ........................................................................ 31
Overview ..................................................................................... 31
DPLL Phase/Frequency Lock Detectors ................................. 31
DPLL Loop Controller ............................................................... 31
Applications Information .............................................................. 32
Optical Networking Line Card ................................................. 32
Small Cell Base Station .............................................................. 33
Initialization Sequence................................................................... 34
Status and Control Pins ................................................................. 37
Multifunction Pins at Reset/Power-Up ................................... 37
Status Functionality.................................................................... 38
Control Functionality ................................................................ 38
Interrupt Request (IRQ) ................................................................ 43
IRQ Monitor ............................................................................... 43
IRQ Mask..................................................................................... 43
IRQ Clear ..................................................................................... 43
Watchdog Timer ............................................................................. 45
Lock Detectors ................................................................................ 46
DPLL Lock Detectors ................................................................ 46
Phase Step Detector ........................................................................ 48
Phase Step Limit ......................................................................... 48
Skew Adjustment ........................................................................ 49
EEPROM Usage .............................................................................. 50
Overview ..................................................................................... 50
EEPROM Controller General Operation ................................ 50
EEPROM Instruction Set .......................................................... 51
Multidevice Support................................................................... 53
Serial Control Port ......................................................................... 55
SPI/I²C Port Selection ................................................................ 55
SPI Serial Port Operation .......................................................... 55
Data Sheet AD9542
Rev. 0 | Page 3 of 61
I2C Serial Port Operation ........................................................... 58
Outline Dimensions ........................................................................ 61
Ordering Guide ........................................................................... 61
REVISION HISTORY
9/2017—Revision 0: Initial Version
AD9542 Data Sheet
Rev. 0 | Page 4 of 61
FUNCTIONAL BLOCK DIAGRAM
AD9542
REFA
Mx PINS
SERIAL PORT
(OPTIONAL EXTERNAL EEPROM)
XOA XOB
OUT0AP
OUT0AN
OUT0BP
OUT0BN
OUT0CP
OUT0CN
OUT1AP
OUT1AN
OUT1BP
OUT1BN
REFB
REFBB
REFAA
REF
DEMOD
REF
DEMOD
÷R
A
÷R
AA
TDC
TDC
REF
DEMOD
REF
DEMOD
÷R
B
÷R
BB
TDC
TDC
REFERENCE
MONITORS
REFERENCE
SWITCHING
AUXILIARY
NCOs
AUXILIARY
TDCs
STATUS AND
CONTROL PINS
EXTERNAL
EEPROM
(OPTIONAL)
SYSTEM
CLOCK PLL
TEMPERATURE
SENSOR
SYSTEM CLOCK
COMPENSATION
INTERNAL
ZERO DELAY
DPLL1 APLL1
SERIAL PORT
(SPI OR I
2
C)
CONTROLLER
3.232GHz
TO
4.04GHz
2.424GHz
TO
3.232GHz
DPLL0 APLL0
DIGITAL
CROSSPOINT
MUX
SYSTEM
CLOCK
÷Q
0A
÷Q
0AA
÷Q
0B
÷Q
0BB
÷Q
0C
÷Q
0CC
÷Q
1A
÷Q
1AA
÷Q
1B
÷Q
1BB
MODULATION, PHASE
OFFSET, AND JESD204B
15826-001
Figure 1.
Data Sheet AD9542
Rev. 0 | Page 5 of 61
SPECIFICATIONS
The minimum and maximum values apply for the full range of supply voltage and operating temperature variations. The typical values
apply for VDD = 1.8 V and TA= 25°C, unless otherwise noted.
SUPPLY VOLTAGE
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
SUPPLY VOLTAGE
VDDIOA, VDDIOB
1.71
1.8
3.465
1.8 V, 2.5 V, and 3.3 V operation supported
VDD
1.71
1.8
1.89
SUPPLY CURRENT
The maximum supply voltage values given in Table 1 are the basis for the maximum supply current specifications. The typical supply
voltage values given in Table 1 are the basis for the typical supply current specifications. The minimum supply voltage values given in
Table 1 are the basis for the minimum supply current specifications.
Table 2.
Parameter Min Typ Max Unit Test Conditions/Comments
SUPPLY CURRENT FOR TYPICAL
CONFIGURATION
The Typical Configuration specification in Table 3 is the basis for
the values shown in this section
I
VDDIOx
5 8 mA Aggregate current for all VDDIOx pins (where x = A or B)
I
VDD
260 310 355 mA Aggregate current for all VDD pins
SUPPLY CURRENT FOR ALL BLOCKS
RUNNING CONFIGURATION
The All Blocks Running condition in Table 3 is the basis for the
values shown in this section
I
VDDIOx
5 8 mA Aggregate current for all VDDIOx pins (where x = A or B)
I
VDD
321 390 430 mA Aggregate current for all VDD pins
POWER DISSIPATION
The typical values apply for VDD = 1.8 V, and the maximum values apply for VDD = 1.89 V.
Table 3.
Parameter Min Typ Max Unit Test Conditions/Comments
POWER DISSIPATION
Typical Configuration 445 560 671 mW System clock = 49.152 MHz crystal; two DPLLs active;
two 19.44 MHz input references in differential mode;
two ac-coupled PLL0 CML output drivers at 245.76 MHz;
and 2 PLL1 CML output drivers at 156.25 MHz
All Blocks Running 548 700 813 mW System clock = 49.152 MHz crystal; two DPLLs active;
two 19.44 MHz input references in differential mode;
3 ac-coupled PLL0 HCSL output drivers at 400 MHz; and
two PLL1 HCSL output drivers at 400 MHz
Full Power-Down 125 mW Based on the Typical Configuration specification with the
power down all bit set to Logic 1
Incremental Power Dissipation Based on the Typical Configuration specification; the values in this
section indicate the change in power due to the indicated
operation relative to the Typical Configuration specification
Complete DPLL/APLL On/Off 200 mW Change in dissipated power relative to the Typical Configuration
specification; the blocks, powered down, consist of 1 reference
input, 1 DPLL, 1 APLL, 2 channel dividers, and 2 output drivers
Incremental Power Dissipation
Complete DPLL/APLL On/Off
200
mW
Based on the Typical Configuration specification; the values in
this section indicate the change in power due to the indicated
operation relative to the Typical Configuration specification;
the blocks, powered down, consist of one reference input, one
DPLL, one APLL, two channel dividers, and two output drivers
AD9542 Data Sheet
Rev. 0 | Page 6 of 61
Parameter Min Typ Max Unit Test Conditions/Comments
Input Reference On/Off
Differential (Normal Mode) 20 mW f
REF
= 19.44 MHz
Differential (DC-Coupled LVDS) 21 mW f
REF
= 19.44 MHz
Single-Ended 13 mW f
REF
= 19.44 MHz
Output Distribution Driver On/Off
At 156.25 MHz
15 mA Mode 30 mW
12 mA Mode 23 mW
7.5 mA Mode 15 mW
Auxiliary DPLL On/Off 1 mW
SYSTEM CLOCK INPUTS, XOA AND XOB
Table 4.
Parameter Min Typ Max Unit Test Conditions/Comments
SYSTEM CLOCK MULTIPLIER
Output Frequency Range 2250 2415 MHz The frequency range of the internal voltage controlled
oscillator (VCO) places limits on the choice of the system
clock input frequency
Phase Frequency Detector (PFD) Rate 20 300 MHz
SYSTEM CLOCK REFERENCE INPUT PATH System clock input must be ac-coupled
Input Frequency Range
System Clock Input Doubler
Disabled 20 300 MHz Support of oven controlled crystal oscillators (OCXOs) <
20 MHz is possible using the auxiliary DPLL for system clock
frequency compensation
Enabled 16 150 MHz
Self Biased Common-Mode Voltage 0.75 V Internally generated
Input Voltage
High
0.9
V
For dc-coupled, single-ended operation
Low 0.5 V For dc-coupled, single-ended operation
Differential Input Voltage Sensitivity 250 mV p-p Minimum voltage swing required (as measured with a
differential probe) across the XOA/XOB pins to ensure
switching between logic states; the instantaneous voltage on
either pin must not exceed 1.2 V; accommodate the single-
ended input by ac grounding the complementary input;
800 mV p-p recommended for optimal jitter performance
Slew Rate for Sinusoidal Input 50 V/µs Minimum input slew rate for device operation; oscillators
with square wave outputs are recommended if not using a
crystal
System Clock Input Divider
(J Divider) Frequency
100 MHz
System Clock Input Doubler
Duty Cycle
Tolerable duty cycle variation on the system clock input
when using the frequency doubler
20 MHz to 150 MHz 43 50 57 %
16 MHz to 20 MHz 47 50 53 %
Input Resistance
5
kΩ
QUARTZ CRYSTAL RESONATOR PATH
Resonator Frequency Range 25 60 MHz Fundamental mode, AT cut crystal
Crystal Motional Resistance 100 Ω A maximum motional resistance of 50 Ω , and maximum
C
LOAD
of 8 pF is strongly recommended for crystals >52 MHz
Data Sheet AD9542
Rev. 0 | Page 7 of 61
REFERENCE INPUTS
Table 5.
Parameter Min Typ Max Unit Test Conditions/Comments
DIFFERENTIAL MODE
Differential mode specifications assume ac coupling
of the input signal to the reference input pins
Frequency Range
Sinusoidal Input 750 MHz Lower limit dependent on input slew rate
LVPECL Input 2000 750 × 106 Hz Lower limit dependent on ac coupling
LVDS Input 2000 500 × 106 Hz Assumes an LVDS minimum of 494 mV p-p differential
amplitude; lower limit dependent on ac coupling
Slew Rate for Sinusoidal input 20 V/µs Minimum input slew rate for device operation; jitter
degradation may occur for slew rates < 35 V/µs
Common-Mode Input Voltage 0.64 V Internally generated self bias voltage
Differential Input Amplitude Peak-to-peak differential voltage swing across pins
required to ensure switching between logic levels as
measured with a differential probe; instantaneous
voltage on either pin must not exceed 1.3 V
f
IN
< 500 MHz 350 2100 mV p-p
f
IN
= 500 MHz to 750 MHz 500 2100 mV p-p
Differential Input Voltage Hysteresis 55 100 mV
Input Resistance
16
kΩ
Equivalent differential input resistance
Input Pulse Width
LVPECL 600 ps
LVDS 900 ps
DC-COUPLED, LVDS-COMPATIBLE
MODE
Applies for dc-coupling to an LVDS source
Frequency Range 2000 450 × 106 Hz
Common-Mode Input Voltage 1.125 1.375 V
Differential Input Amplitude
400
1200
mV p-p
Differential voltage across pins required to ensure
switching between logic levels; instantaneous
voltage on either pin must not exceed the supply rails
Differential Input Voltage Hysteresis 55 100 mV
Input Resistance 16 kΩ
Input Pulse Width 1 ns
SINGLE-ENDED MODE Single-ended mode specifications assume dc
coupling of the input signal to the reference input
pins
Frequency Range
1.2 V AC-Coupled 2000 500 × 10
6
Hz Lower limit dependent on ac-coupling
1.2 V and 1.8 V CMOS 2000 500 × 106 Hz CMOS specifications assume dc coupling of the input
signal to the reference input pins
1.2 V AC-Coupled Common-Mode
Voltage
610 mV Internally generated self-bias voltage
Input Amplitude (Single-Ended,
AC-Coupled Mode)
360 1200 mV p-p Peak-to-peak single-ended voltage swing;
instantaneous voltage must not exceed 1.3 V
1.2 V and 1.8 V CMOS Input
Voltage
High, VIH 0.65 ×
V
REF
1.15 × VREF V VREF is determined by operating mode of the CMOS
input receiver, 1.2 V or 1.8 V
Low, V
IL
0.35 × V
REF
V
Input Resistance
DC-Coupled Single-Ended
Mode
30 kΩ
AC-Coupled Single-Ended
Mode
15 kΩ
Input Pulse Width 900 ps
AD9542 Data Sheet
Rev. 0 | Page 8 of 61
REFERENCE MONITORS
Table 6.
Parameter Min Typ Max Unit Test Conditions/Comments
REFERENCE MONITORS
Reference Monitor
Loss of Reference
Detection Time
4.9 + 0.13 × tPFD µs tPFD is the nominal phase detector period, R/fREF, where R is
the frequency division factor determined by the R divider,
and f
REF
is the frequency of the active reference
Frequency Out of
Range Limits
5 × 10−8 0.015 ppb Parts per billion (ppb) is defined as Δf/fREF, where Δf is the
frequency deviation, and fREF is the reference input
frequency; programmable with the lower bound, subject
to quality of the system clock (or the source of system
clock compensation)
Validation Timer 0.001 1048 sec Programmable in 1 ms increments
Excess Jitter Alarm Threshold 1 65535 ns Programmable in 1 ns increments
DPLL PHASE CHARACTERISTICS
Table 7.
Parameter Min Typ Max Unit Test Conditions/Comments
MAXIMUM OUTPUT PHASE
PERTURBATION
Assumes a jitter free reference; satisfies Telcordia GR-1244-CORE
requirements; 0 ppm frequency difference between references;
reference switch initiated via register map (see the AD9542 Register
Map Reference Manual) by faulting the active reference input
Phase Refinement Disabled 50 Hz DPLL loop bandwidth; normal phase margin mode; frequency
translation = 19.44 MHz to 155.52 MHz; 49.152 MHz signal generator
used for system clock source
Peak ±20 ±140 ps
Steady State
Phase Buildout Operation ±18 ±125 ps
Hitless Operation 0 ps
Phase Refinement Enabled 50 Hz DPLL loop bandwidth; high phase margin mode; phase
refinement iterations = 4; frequency translation = 19.44 MHz to
155.52 MHz; 49.152 MHz signal generator used for system clock source
Peak ±5 ±40 ps
Steady State
Phase Buildout Operation ±4 ±35 ps
Hitless Operation 0 ps
PHASE SLEW LIMITER 0.001 250 µs/sec See the AN-1420 Application Note, Phase Buildout and Hitless
Switchover with Digital Phase-Locked Loops (DPLLs)
Data Sheet AD9542
Rev. 0 | Page 9 of 61
DISTRIBUTION CLOCK OUTPUTS
Table 8.
Parameter Min Typ Max Unit Test Conditions/Comments
DIFFERENTIAL MODE
All testing is both ac-coupled and dc-coupled
Output Frequency Frequency range determined by driver
functionality; actual frequency synthesis may be
limited by the APLL VCO frequency range
CML 1 500 × 106 Hz Terminated per Figure 33
HCSL 1 500 × 106 Hz Terminated per Figure 32
Differential Output Voltage Swing
Voltage between output pins measured with
output driver static; peak-to-peak differential
output amplitude is twice that shown when driver
is toggling and measured using a differential probe
Output Current = 7.5 mA
HCSL
312
368
402
mV
Terminated per Figure 32
CML 257 348 408 mV Terminated to VDD (nominal 1.8 V) per Figure 33
Output Current = 15 mA
HCSL 631 745 809 mV Terminated per Figure 32
CML 578 729 818 mV Terminated to VDD (nominal 1.8 V) per Figure 33
Common-Mode Output Voltage
Output Current = 7.5 mA
HCSL
155 184 201 mV Terminated per Figure 32
CML VDD − 208 VDD − 188 VDD − 169 mV Terminated to VDD (nominal 1.8 V) per Figure 33
(maximum common-mode voltage case occurs at
the minimum amplitude)
Output Current = 15 mA
HCSL
316 372 405 mV Terminated per Figure 32
CML VDD − 416 VDD − 371 VDD − 327 mV Terminated to VDD (nominal 1.8 V) per Figure 33
(maximum common-mode voltage case occurs at
the minimum amplitude)
SINGLE-ENDED MODE
Output Frequency 1 500 × 106 Hz Frequency range determined by driver
functionality; actual frequency synthesis may be
limited by the APLL VCO frequency range
Output Current = 12 mA
Voltage Swing (Peak-to-Peak)
HCSL Driver Mode 509 584 634 mV Each output terminated per Figure 37 with R
L
= 50 Ω
CML Driver Mode 456 565 644 mV Each output terminated per Figure 37 with RL = 50 Ω
connected to VDD (nominal 1.8 V) instead of GND
Voltage Swing Midpoint
HCSL Driver Mode 255 292 317 mV Each output terminated per Figure 37 with R
L
= 50 Ω
CML Driver Mode VDD − 325 VDD − 291 VDD − 266 mV Each output terminated per Figure 37 with RL = 50 Ω
connected to VDD (nominal 1.8 V) instead of GND
Output Current = 15 mA
Voltage Swing (Peak-to-Peak)
HCSL Driver Mode
645
734
796
mV
Each output terminated per Figure 37 with RL = 50 Ω
CML Driver Mode 589 721 815 mV Each output terminated per Figure 37 with RL = 50 Ω
connected to VDD (nominal 1.8 V) instead of GND
Voltage Swing Midpoint
HCSL Driver Mode 322 367 398 mV Each output terminated per Figure 37 with R
L
= 50 Ω
CML Driver Mode VDD − 411 VDD − 367 VDD − 334 mV Each output terminated per Figure 37 with RL = 50 Ω
connected to VDD (nominal 1.8 V) instead of GND
AD9542 Data Sheet
Rev. 0 | Page 10 of 61
TIME DURATION OF DIGITAL FUNCTIONS
Table 9.
Parameter Min Typ Max Unit Test Conditions/Comments
TIME DURATION OF DIGITAL
FUNCTIONS
EEPROM to Register Download
Time
10 ms Using the Typical Configuration from Table 3
Power-On Reset (POR) 25 ms Time from power supplies > 80% to release of internal reset
Mx Pin to RESETB Rising Edge
Setup Time
1 ns Mx refers to Pin M0 through Pin M6
Mx Pin to RESETB Rising Edge
Hold Time
2 ns
Multiple Mx Pin Timing Skew 39 ns Applies only to multibit Mx pin functions
RESETB Falling Edge to Mx Pin
High-Z Time
14 ns
TIME FROM START OF DPLL
ACTIVATION TO ACTIVE PHASE
DETECTOR OUTPUT
Untagged Operation 10 tPFD tPFD is the nominal phase detector period given by R/fREF, where R is the
frequency division factor determined by the R divider, and fREF is the
frequency of the active reference
Tagged Operation 10 Tag
period
Tag period = (tag ratio/fTAG), where fTAG is either fREF (for tagged reference
mode) or fFEEDBACK (for all other tagged modes); the tag ratio corresponds to
the selection of f
TAG
DIGITAL PLL (DPLL0, DPLL1) SPECIFICATIONS
Table 10.
Parameter Min Typ Max Unit Test Conditions/Comments
DIGITAL PLL
Digital Phase Detector (DPD)
Input Frequency Range
1 2 ×
10
5
Hz
Loop Filter
Profile 0
Bandwidth 0.0001 1850 Hz Programmable design parameter; (f
PFD
/bandwidth) ≥ 20
Phase Margin
70
Degrees
Closed-Loop Peaking 1.1 dB
Profile 1
Bandwidth 0.0001 305 Hz Programmable design parameter; (f
PFD
/bandwidth) ≥ 20
Phase Margin 88.5 Degrees
Closed-Loop Peaking
0.1
dB
In accordance with Telcordia GR-253-CORE jitter transfer
specifications
DIGITAL PLL NCO Division Ratio These specifications cover limitations on the DPLLx frequency
tuning word (FTW0); the AD9542 evaluation software frequency
planning wizard sets these values automatically for the user, and
the AD9542 evaluation software is available for download from
the AD9542 product page at www.analog.com/AD9542; NCO
division = 248/FTW0, which takes the form INT.FRAC, where INT is
the integer portion, and FRAC is the fractional portion
NCO Integer
7
13
This is the integer portion of NCO division
NCO Fraction 0.05 0.95 This is the fractional portion of NCO division
Data Sheet AD9542
Rev. 0 | Page 11 of 61
DIGITAL PLL LOCK DETECTION SPECIFICATIONS
Table 11.
Parameter Min Typ Max Unit Test Conditions/Comments
PHASE LOCK DETECTOR
Threshold Programming Range 10 2
24
− 1 ps
Threshold Resolution 1 ps
FREQUENCY LOCK DETECTOR
Threshold Programming Range 10 2
24
− 1 ps
Threshold Resolution 1 ps
PHASE STEP DETECTOR
Threshold Programming Range 100 2
32
− 1 ps Setting this value too low causes false triggers
Threshold Resolution 1 ps
HOLDOVER SPECIFICATIONS
Table 12.
Parameter Min Typ Max Unit Test Conditions/Comments
HOLDOVER SPECIFICATIONS
Initial Frequency Accuracy ±0.01 ±0.1 ppb AD9542 is configured using Configuration 1 from Table 21;
excludes frequency drift of system clock (SYSCLK) source;
excludes frequency drift of input reference prior to
entering holdover; 160 ms history timer; history holdoff
setting of 8; three holdover history features (bits) are
enabled: delay history until frequency lock bit, delay
history until phase lock bit, and delay holdover history
accumulation until not phase slew limited bit
Relative Frequency Accuracy
Between Channels
Cascaded Operation 0 ppb
History Averaging Window 0.001 268435 sec
ANALOG PLL (APLL0, APLL1) SPECIFICATIONS
Table 13.
Parameter Min Typ Max Unit
VCO FREQUENCY RANGE
Analog PLL0 (APLL0) 2424 3232 MHz
Analog PLL1 (APLL1) 3232 4040 MHz
PHASE FREQUENCY DETECTOR (PFD) INPUT FREQUENCY RANGE 162 350 MHz
LOOP BANDWIDTH 260 kHz
PHASE MARGIN 68 Degrees
OUTPUT CHANNEL DIVIDER SPECIFICATIONS
Table 14.
Parameter Min Typ Max Unit Test Conditions/Comments
OUTPUT PHASE ADJUST STEP SIZE 1 t
VCO
t
VCO
= 1/(APLLx VCO frequency), where x = 0, 1
AD9542 Data Sheet
Rev. 0 | Page 12 of 61
SYSTEM CLOCK COMPENSATION SPECIFICATIONS
Table 15.
Parameter Min Typ Max Unit Test Conditions/Comments
DIRECT COMPENSATION
Resolution 0.028 ppt ppt is parts per trillion (10
−12
)
CLOSED-LOOP COMPENSATION (AUXILIARY DPLL)
Phase Detector Frequency
2
200
kHz
Loop Bandwidth 0.1 2 × 10
3
Hz
Reference Monitor Threshold 5 %
TEMPERATURE SENSOR SPECIFICATIONS
Table 16.
Parameter Min Typ Max Unit Test Conditions/Comments
TEMPERATURE
Accuracy
Absolute 5 °C T
A
= −50°C to +110°C
Relative 1.7 % T
A
= −50°C to +110°C
Resolution
0.0078
°C
16-bit (signed) resolution
Conversion time 0.18 ms
REPEATABILITY
±0.02
°C
TA = 25°C
DRIFT 0.1 °C 500 hour stress test at 100°C
SERIAL PORT SPECIFICATIONS
Serial Port Interface (SPI) Mode
Table 17.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
CSB Valid for VDDIOA = 3.3 V, 1.8 V, and 2.5 V
Input Logic 1 Voltage VDDIOA − 0.4 V
Input Logic 0 Voltage 0.4 V
Input Logic 1 Current 1 µA
Input Logic 0 Current 1 µA
SCLK
Input Logic 1 Voltage VDDIOA − 0.4 V
Input Logic 0 Voltage 0.4 V
Input Logic 1 Current 1 µA
Input Logic 0 Current 1 µA
SDIO
As an Input
Input Logic 1 Voltage VDDIOA − 0.4 V
Input Logic 0 Voltage 0.4 V
Input Logic 1 Current 1 µA
Input Logic 0 Current 1 µA
As an Output
Output Logic 1 Voltage VDDIOA − 0.2 V 1 mA load current
Output Logic 0 Voltage
0.2
V
1 mA load current
SDO
Output Logic 1 Voltage VDDIOA − 0.2 V 1 mA load current
Output Logic 0 Voltage 0.2 V 1 mA load current
Leakage Current ±1 µA SDO inactive (high impedance)
TIMING Valid for VDDIOA = 3.3 V, 1.8 V, and 2.5 V
Data Sheet AD9542
Rev. 0 | Page 13 of 61
Parameter Min Typ Max Unit Test Conditions/Comments
SCLK
Clock Rate, 1/t
CLK
50 MHz
Pulse Width High, t
HIGH
5 ns
Pulse Width Low, t
LOW
9 ns
SDIO to SCLK Setup, tDS
2.2
ns
SCLK to SDIO Hold, t
DH
0 ns
SCLK to Valid SDIO and SDO, t
DV
9 ns
CSB to SCLK Setup, t
S
1.5 ns
CSB to SCLK Hold, t
C
0 ns
CSB Minimum Pulse Width High 1 t
CLK
I2C Mode
Table 18.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
SDA, SCL (AS INPUTS) Valid for VDDIOA = 3.3 V, 1.8 V, and 2.5 V
Input Logic 1 Voltage 70 % of VDDIOA
Input Logic 0 Voltage 0.3 ×
VDDIOA
V
Input Current −10 +10 µA For V
IN
= 10% to 90% of VDDIOA
Hysteresis of Schmitt Trigger Inputs 1.5 % of VDDIOA
SDA (AS OUTPUT)
Output Logic 0 Voltage 0.2 V I
OUT
= 3 mA
Output Fall Time from VIH Minimum
to V
IL
Maximum
20 + 0.1 × CB 250 ns 10 pF ≤ CB ≤ 400 pF
TIMING
SCL Clock Rate 400 kHz
Bus Free Time Between a Stop and
Start Condition, t
BUF
1.3 µs
Repeated Start Condition Setup
Time, t
SU; STA
0.6 µs
Repeated Hold Time Start
Condition, t
HD; STA
0.6 µs After this period, the first clock pulse is
generated
Stop Condition Setup Time, t
SU; STO
0.6 µs
Low Period of the SCL Clock, t
LOW
1.3 µs
High Period of the SCL Clock, t
HIGH
0.6 µs
SCL/SDA Rise Time, t
R
20 + 0.1 × C
B
300 ns
SCL/SDA Fall Time, t
F
20 + 0.1 × C
B
300 ns
Data Setup Time, t
SU; DAT
100 ns
Data Hold Time, t
HD; DAT
100 ns
Capacitive Load for Each Bus Line, CB
400
pF
AD9542 Data Sheet
Rev. 0 | Page 14 of 61
LOGIC INPUT SPECIFICATIONS (RESETB, M0 TO M6)
Table 19.
Parameter Min Typ Max Unit Test Conditions/Comments
RESETB
Valid for 3.3 V ≥ VDDIOA ≥ 1.8 V; internal 100 kΩ pull-up resistor
Input High Voltage (V
IH
) VDDIOA − 0.4 V
Input Low Voltage (V
IL
) 0.4 V
Input Current High (I
INH
) 1 µA
Input Current Low (I
INL
) ±15 ±125 µA
LOGIC INPUTS (M0 to M6) Valid for 3.3 V ≥ VDDIOx ≥ 1.8 V; VDDIOA applies to the M5 pin and
the M6 pin; VDDIOB applies to the M0, M1, M2, M3, and M4 pins;
the M3 and M4 pins have internal 100 kΩ pull-down resistors
Frequency Range 51 MHz
Input High Voltage (V
IH
) VDDIOx − 0.4 V
Input Low Voltage (V
IL
) 0.4 V
Input Current (I
INH
, I
INL
) ±15 ±125 µA
LOGIC OUTPUT SPECIFICATIONS (M0 TO M6)
Table 20.
Parameter Min Typ Max Unit Test Conditions/Comments
LOGIC OUTPUTS (M0 to M6) Valid for 3.3 V ≥ VDDIOx ≥ 1.8 V; VDDIOA applies for the M5 and
M6 pins; VDDIOB applies for M0 to M4; normal (default) output
drive current setting for M0 through M6
Frequency Range 26 MHz
Output High Voltage (V
OH
) VDDIOx − 0.6 V Load current = 10 mA
VDDIOx – 0.2 V Load current = 1 mA
Output Low Voltage (V
OL
) 0.6 V Load current = 10 mA
0.2 V Load current = 1 mA
JITTER GENERATION (RANDOM JITTER)
Table 21.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
JITTER GENERATION System clock doubler enabled; high phase margin mode enabled;
there is not a significant jitter difference between driver modes
Channel 0—DPLL0, APLL0 Channel 1 powered down
RMS Jitter (12 kHz to 20 MHz)
Configuration 1—155.52 MHz 223 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 38.88 MHz, fVCO =
2488.32 MHz, fOUT = 155.52 MHz, BWDPLL = 50 Hz, phase buildout
operation
Configuration 2—245.76 MHz 220 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 30.72 MHz, fVCO =
2457.6 MHz, fOUT = 245.76 MHz, BWDPLL = 50 Hz, internal zero delay
operation
Configuration 3—491.52 MHz 235 fs Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz
temperature compensated crystal oscillator (TCXO), BWCOMP =
50 Hz, fREF = 1 Hz, fVCO = 2949.12 MHz, fOUT = 491.52 MHz, BWDPLL =
50 mHz, phase buildout operation
Configuration 4—125 MHz 213 fs Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz TCXO,
BWCOMP = 50 Hz, fREF = 125 MHz, fVCO = 2500 MHz, fOUT = 125 MHz,
BW
DPLL
= 0.1 Hz, phase buildout operation
Configuration 5—312.5 MHz 217 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 25 MHz, fVCO =
2500 MHz, fOUT = 312.5 MHz, BWDPLL = 50 Hz, phase buildout
operation
Configuration 6—174.7030837 MHz 230 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 155.52 MHz, fVCO =
2620.5463 MHz, f
OUT
= (155.52 × 255/227) MHz, BW
DPLL
= 50 Hz
Data Sheet AD9542
Rev. 0 | Page 15 of 61
Parameter Min Typ Max Unit Test Conditions/Comments
Channel 1—DPLL1, APLL1 Channel 0 powered down
RMS Jitter (12 kHz to 20 MHz)
Configuration 1—155.52 MHz 247 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 38.88 MHz, fVCO =
3265.92 MHz, fOUT = 155.52 MHz, BWDPLL = 50 Hz, phase buildout
operation, half divide enabled
Configuration 2—245.76 MHz 280 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 30.72 MHz, fVCO =
3686.4 MHz, fOUT = 245.76 MHz, BWDPLL = 50 Hz, half divide enabled,
internal zero delay operation
Configuration 3—491.52 MHz 323 fs Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz TCXO,
BWCOMP = 50 Hz, fREF = 1 Hz, fVCO = 3932.16 MHz, fOUT = 491.52 MHz,
BW
DPLL
= 50 mHz, phase buildout operation
Configuration 4—125 MHz 243 fs Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz TCXO,
BWCOMP = 50 Hz, fREF = 125 MHz, fVCO = 3250 MHz, fOUT = 125 MHz,
BW
DPLL
= 0.1 Hz, phase buildout operation
Configuration 5—312.5 MHz 266 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 25 MHz, fVCO =
3750 MHz, fOUT = 312.5 MHz, BWDPLL = 50 Hz, phase buildout
operation
Configuration 6—174.7030837 MHz 264 fs Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 155.52 MHz,
fVCO = 3319.3586 MHz, fOUT = (155.52 × 255/227) MHz, BWDPLL =
50 Hz, phase buildout operation
PHASE NOISE
Table 22.
Parameter Min Typ Max Unit Test Conditions/Comments
PHASE NOISE
System clock doubler enabled; high phase margin mode
enabled; there is not a significant jitter difference between
driver modes
Channel 0—DPLL0, APLL0 Channel 1 powered down
RMS Jitter (12 kHz to 20 MHz)
Configuration 1—155.52 MHz
Device configuration: f
SYSCLK
= 52 MHz XTAL, f
REF
= 38.88 MHz, f
VCO
= 2488.32 MHz, fOUT = 155.52 MHz, BWDPLL = 50 Hz, phase
buildout operation
10 Hz Offset −81 dBc/Hz
100 Hz Offset −98 dBc/Hz
1 kHz Offset −118 dBc/Hz
10 kHz Offset −128 dBc/Hz
100 kHz Offset −134 dBc/Hz
1 MHz Offset −144 dBc/Hz
10 MHz Offset −158 dBc/Hz
Floor −161 dBc/Hz
Configuration 2—245.76 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 30.72 MHz, fVCO =
2457.6 MHz, fOUT = 245.76 MHz, BWDPLL = 50 Hz, internal zero delay
operation
10 Hz Offset −77 dBc/Hz
100 Hz Offset −93 dBc/Hz
1 kHz Offset −114 dBc/Hz
10 kHz Offset −125 dBc/Hz
100 kHz Offset −130 dBc/Hz
1 MHz Offset −140 dBc/Hz
10 MHz Offset −156 dBc/Hz
Floor −161 dBc/Hz
Configuration 3—491.52 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz TCXO,
BWCOMP = 50 Hz, fREF = 1 Hz, fVCO = 2949.12 MHz, fOUT = 491.52 MHz,
BWDPLL = 50 mHz, phase buildout operation
10 Hz Offset −74 dBc/Hz
100 Hz Offset
−89
dBc/Hz
1 kHz Offset −108 dBc/Hz
AD9542 Data Sheet
Rev. 0 | Page 16 of 61
Parameter Min Typ Max Unit Test Conditions/Comments
10 kHz Offset −119 dBc/Hz
100 kHz Offset −123 dBc/Hz
1 MHz Offset −134 dBc/Hz
10 MHz Offset −152 dBc/Hz
Floor −159
Configuration 4—125 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz
TCXO, BWCOMP = 50 Hz, fREF = 125 MHz, fVCO = 2500 MHz, fOUT =
125 MHz, BW
DPLL
= 0.1 Hz, phase buildout operation
10 Hz Offset −84 dBc/Hz
100 Hz Offset −106 dBc/Hz
1 kHz Offset −120 dBc/Hz
10 kHz Offset −131 dBc/Hz
100 kHz Offset
−136
dBc/Hz
1 MHz Offset −147 dBc/Hz
10 MHz Offset −160 dBc/Hz
Floor −163 dBc/Hz
Configuration 5—312.5 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 25 MHz, fVCO =
2500 MHz, fOUT = 312.5 MHz, BWDPLL = 50 Hz, phase buildout
operation
10 Hz Offset −74 dBc/Hz
100 Hz Offset −91 dBc/Hz
1 kHz Offset −112 dBc/Hz
10 kHz Offset −123 dBc/Hz
100 kHz Offset −128 dBc/Hz
1 MHz Offset −138 dBc/Hz
10 MHz Offset
−154
dBc/Hz
Floor −161 dBc/Hz
Configuration 6—174.7030837 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 155.52 MHz, fVCO
= 2620.5463 MHz, f
OUT
= (155.52 × 255/227) MHz, BW
DPLL
= 50 Hz
10 Hz Offset −82 dBc/Hz
100 Hz Offset
−99
dBc/Hz
1 kHz Offset −117 dBc/Hz
10 kHz Offset −127 dBc/Hz
100 kHz Offset
−133
dBc/Hz
1 MHz Offset −143 dBc/Hz
10 MHz Offset −157 dBc/Hz
Floor −160 dBc/Hz
Channel 1—DPLL1, APLL1 Channel 0 powered down
RMS Jitter (12 kHz to 20 MHz)
Configuration 1—155.52 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 38.88 MHz, fVCO =
3265.92 MHz, fOUT = 155.52 MHz, BWDPLL = 50 Hz, phase buildout
operation, half divide enabled
10 Hz Offset −81 dBc/Hz
100 Hz Offset
−98
dBc/Hz
1 kHz Offset −118 dBc/Hz
10 kHz Offset −128 dBc/Hz
100 kHz Offset −132 dBc/Hz
1 MHz Offset −144 dBc/Hz
10 MHz Offset −158 dBc/Hz
Floor −162 dBc/Hz
Configuration 2—245.76 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 30.72 MHz, fVCO =
3686.4 MHz, fOUT = 245.76 MHz, BWDPLL = 50 Hz, half divide
enabled; internal zero delay operation
10 Hz Offset −76 dBc/Hz
100 Hz Offset −93 dBc/Hz
1 kHz Offset −114 dBc/Hz
10 kHz Offset
−124
dBc/Hz
Data Sheet AD9542
Rev. 0 | Page 17 of 61
Parameter Min Typ Max Unit Test Conditions/Comments
100 kHz Offset −127 dBc/Hz
1 MHz Offset −138 dBc/Hz
10 MHz Offset −156 dBc/Hz
Floor −161 dBc/Hz
Configuration 3—491.52 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz TCXO,
BWCOMP = 50 Hz, fREF = 1 Hz, fVCO = 3932.16 MHz, fOUT = 491.52 MHz,
BW
DPLL
= 50 mHz, phase buildout operation
10 Hz Offset −74 dBc/Hz
100 Hz Offset −90 dBc/Hz
1 kHz Offset −108 dBc/Hz
10 kHz Offset −118 dBc/Hz
100 kHz Offset −120 dBc/Hz
1 MHz Offset
−131
dBc/Hz
10 MHz Offset −150 dBc/Hz
Floor −160 dBc/Hz
Configuration 4—125 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fCOMP = 19.2 MHz
TCXO, BWCOMP = 50 Hz, fREF = 125 MHz, fVCO = 3250 MHz, fOUT =
125 MHz, BW
DPLL
= 0.1 Hz, phase buildout operation
10 Hz Offset −83 dBc/Hz
100 Hz Offset −106 dBc/Hz
1 kHz Offset −120 dBc/Hz
10 kHz Offset −131 dBc/Hz
100 kHz Offset −135 dBc/Hz
1 MHz Offset −145 dBc/Hz
10 MHz Offset −160 dBc/Hz
Floor
−163
dBc/Hz
Configuration 5—312.5 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 25 MHz, fVCO =
3750 MHz, fOUT = 312.5 MHz, BWDPLL = 50 Hz, phase buildout
operation
10 Hz Offset −73 dBc/Hz
100 Hz Offset −91 dBc/Hz
1 kHz Offset −112 dBc/Hz
10 kHz Offset −122 dBc/Hz
100 kHz Offset −125 dBc/Hz
1 MHz Offset −137 dBc/Hz
10 MHz Offset −154 dBc/Hz
Floor −161 dBc/Hz
Configuration 6—174.7030837 MHz Device configuration: fSYSCLK = 52 MHz XTAL, fREF = 155.52 MHz, fVCO
= 3319.3586 MHz, f
OUT
= (155.52 × 255/227) MHz, BW
DPLL
= 50 Hz
10 Hz Offset −77 dBc/Hz
100 Hz Offset −99 dBc/Hz
1 kHz Offset −117 dBc/Hz
10 kHz Offset −127 dBc/Hz
100 kHz Offset
−131
dBc/Hz
1 MHz Offset −142 dBc/Hz
10 MHz Offset −158 dBc/Hz
Floor −161 dBc/Hz
AD9542 Data Sheet
Rev. 0 | Page 18 of 61
ABSOLUTE MAXIMUM RATINGS
Table 23.
Parameter Rating
1.8 V Supply Voltage (VDD) 2 V
Input/Output Supply Voltage
(VDDIOA, VDDIOB)
3.6 V
Input Voltage Range (XOA, XOB,
REFA, REFAA, REFB, REFBB Pins)
−0.5 V to VDD + 0.5 V
Digital Input Voltage Range
SDO/M5, SCLK/SCL, SDIO/SDA,
CSB/M6 Pins
−0.5 V to VDDIOA + 0.5 V
M0, M1, M2, M3, M4 Pins −0.5 V to VDDIOB + 0.5 V
Storage Temperature Range −65°C to +150°C
Operating Temperature Range1 −40°C to +85°C
Lead Temperature (Soldering 10 sec) 300°C
1 See the Thermal Resistance section for additional information.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
Thermal performance is directly linked to printed circuit board
(PCB) design and operating environment. Careful attention to
PCB thermal design is required.
Table 24. Thermal Resistance
Symbol
Thermal Characteristic Using a
JEDEC51-7 Plus JEDEC51-5 2S2P
Test Board1 Value Unit
θJA Junction to ambient thermal
resistance, 0.0 m/sec airflow per
JEDEC JESD51-2 (still air)
23.92 °C/W
θJMA Junction to ambient thermal
resistance, 1.0 m/sec airflow per
JEDEC JESD51-6 (moving air)
19.42 °C/W
θJMA Junction to ambient thermal
resistance, 2.5 m/sec airflow per
JEDEC JESD51-6 (moving air)
18.22 °C/W
θJC Junction to case thermal resistance
(die to heat sink) per MIL-STD 883,
Method 1012.1
1.52 °C/W
1 The exposed pad on the bottom of the package must be soldered to ground
to achieve the specified thermal performance.
Values of θJA are for package comparison and PCB design
considerations. θJA provides for a first-order approximation of TJ
per the following equation:
TJ = TA + (θJA × PD)
where TA is the ambient temperature (°C).
Values of θJC are for package comparison and PCB design
considerations when an external heat sink is required.
ESD CAUTION
Data Sheet AD9542
Rev. 0 | Page 19 of 61
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
M3
4
5
6
7
24VDD 23
22
21
20
19
18
17
16
15
14
13VDD
44
45
46
47
48 RESETB
43
42
41
40
39
38
37 M4
25
OUT0AN 26
27
28
29
30
31
32
33
34
35
36
SDO/M5
8
9
10
11
12 OUT1AP
REFA
REFAA
VDD
DNC
XOB
XOA
VDD
VDD
REFBB
REFB
SDIO/SDA
CSB/M6
OUT0AP
VDDIOA
SCLK/SCL
VDD
VDD
VDD
LF0
LDO0
AD9542
TOP VIEW
(No t t o Scal e)
OUT0BP
OUT0BN
DNC
OUT0CP
OUT0CN
VDD
VDD
DNC
OUT1BP
OUT1BN
VDD
M1
OUT1AN
M2
VDD
LDO1
VDD
LF1
M0
VDDIOB
NOTES
1. EX P OSE D P AD. T HE E X P OSE D P AD IS THE G ROUND CO NNE CTI ON
ON THE CHIP. THE EXPOSED PAD MUST BE SOLDERED T O T HE
ANALO G G ROUND O F T HE P CB TO E NS URE P ROPE R
FUNCTIONALITY AND FOR HEAT DISSIPATION, NOISE, AND
MECHANI CAL STRENGT H BE NE FI TS.
2. DNC = DO NOT CONNECT. LEAVE THESE PINS FLOATING.
15826-002
Figure 2. Pin Configuration
Table 25. Pin Function Descriptions
Pin No. Mnemonic
Input/
Output Pin Type Description
1 SDO/M5 Output CMOS Serial Data Output (SDO). This pin is for reading serial data in 4-wire SPI mode.
Changes to the VDDIOA supply voltage affect the V
IH
and V
OH
values for this pin.
Configurable Input/Output (M5).This pin is a status and control pin when the
device is not in 4-wire SPI mode.
2 SCLK/SCL Input CMOS Serial Programming Clock (SCLK) Pin in SPI Mode. Changes to the VDDIOA supply
voltage affect the V
IH
and V
OH
values for this pin.
Serial Clock Pin (SCL) in I2C Mode. Changes to the VDDIOA supply voltage affect the
V
IH
and V
OH
values for this pin.
3 VDDIOA Input Power Serial Port Power Supply. The valid supply voltage is 1.8 V, 2.5 V, or 3.3 V. The
VDDIOA pin can be connected to the VDD supply bus if 1.8 V operation is desired.
4 SDIO/SDA Input/
output
CMOS Serial Data Input/Output in SPI Mode (SDIO). Write data to this pin in 4-wire SPI
mode. This pin has no internal pull-up or pull-down resistor. Changes to the VDDIOA
supply voltage affect the V
IH
and V
OH
values for this pin.
Serial Data Pin in I
2
C Mode (SDA).
5 CSB/M6 Input/
output
CMOS Chip Select in SPI Mode (CSB). Active low input. Maintain a Logic 0 level on this pin
when programming the device in SPI mode. This pin has an internal 10 kΩ pull-up
resistor. Changes to the VDDIOA supply voltage affect the V
IH
and V
OH
values for this pin.
Configurable Input/Output (M6). This pin is a status and control pin when the
device is not in SPI mode.
6, 9, 10, 13,
19, 20, 24,
27, 28, 31,
40, 41, 45
VDD Input Power 1.8 V Power Supply.
7 LDO0 Input LDO bypass APLL0 Loop Filter Voltage Regulator. Connect a 0.22 μF capacitor from this pin to
ground. This pin is the ac ground reference for the integrated APLL0 loop filter.
8 LF0 Input/
output
Loop filter
for APLL0
Loop Filter Node for APLL0. Connect a 3.9 nF capacitor from this pin to Pin 7
(LDO0).
11 OUT0AP Output HCSL, LVDS,
CML, CMOS
PLL0 Output 0A.
12 OUT0AN Output HCSL, LVDS,
CML, CMOS
PLL0 Complementary Output 0A.
AD9542 Data Sheet
Rev. 0 | Page 20 of 61
Pin No. Mnemonic
Input/
Output Pin Type Description
14 OUT0BP Output HCSL, LVDS,
CML, CMOS
PLL0 Output 0B.
15 OUT0BN Output HCSL, LVDS,
CML, CMOS
PLL0 Complementary Output 0B.
16, 21, 44 DNC DNC No Connect Do Not Connect. Leave these pins floating.
17 OUT0CP Output HCSL, LVDS,
CML, CMOS
PLL0 Output 0C.
18 OUT0CN Output HCSL, LVDS,
CML, CMOS
PLL0 Complementary Output 0C.
22 OUT1BP Output HCSL, LVDS,
CML, CMOS
PLL1 Output 1B.
23 OUT1BN Output HCSL, LVDS,
CML, CMOS
PLL1 Complementary Output 1B.
25 OUT1AP Output HCSL, LVDS,
CML, CMOS
PLL1 Output 1A.
26 OUT1AN Input/
Output
HCSL, LVDS,
CML, CMOS
PLL1 Complementary Output 1A.
29 LF1 Input/
output
Loop filter
for APLL1
Loop Filter Node for APLL1. Connect a 3.9 nF capacitor from this pin to Pin 30 (LDO1).
30 LDO1 Input LDO bypass APLL1 Loop Filter Voltage Regulator. Connect a 0.1 μF capacitor from this pin to
ground. This pin is the ac ground reference for the integrated APLL1 loop filter.
32, 33, 35,
36, 37
M0, M1,
M2, M3, M4
Input/
output
CMOS Configurable Input/Output Pins. These are status and control pins. Changes to the
VDDIOB supply voltage affect the VIH and VOH values for these pins. M3 and M4 have
internal 100 kΩ pull-down resistors. M0, M1, and M2 do not have internal resistors.
34 VDDIOB Input Power Mx Pin Power Supply. This power supply powers the digital section that controls
the M0 to M4 pins. Valid supply voltages are 1.8 V, 2.5 V, or 3.3 V. The VDDIOB pin
can be connected to the VDD supply bus if 1.8 V operation is desired.
38 REFB Input 1.8 V single-
ended or
differential
input
Reference B Input. This internally biased input is typically ac-coupled; when
configured in this manner, it can accept any differential signal with a single-ended
swing up to the VDD power supply. If dc-coupled, the input can be LVDS or single-
ended 1.8 V CMOS.
39 REFBB Input 1.8 V single-
ended or
differential
input
Reference BB Input or Complementary Reference B Input. If REFB is in differential
mode, the REFB complementary signal is on this pin. No connection is necessary to
this pin if REFB is a single-ended input and REFBB is not used.
42 XOA Input Differential
input
System Clock Input. XOA contains internal dc biasing and is ac-coupled with a 0.01 μF
capacitor except when using a crystal. When a crystal is used, connect the crystal
across XOA and XOB. A single-ended CMOS input is also an option, but it can
produce spurious spectral content when the duty cycle is not 50%. When using
XOA as a single-ended input, connect a 0.1 μF capacitor from XOB to ground.
43 XOB Input Differential
input
Complementary System Clock Input. Complementary signal to XOA. XOB contains
internal dc biasing and is ac-coupled with a 0.1 μF capacitor except when using a
crystal. When a crystal is used, connect the crystal across XOA and XOB.
46 REFAA Input 1.8 V single-
ended or
differential
input
Reference AA input or Complementary REFA Input. If REFA is in differential mode,
the REFA complementary signal is on this pin. No connection is necessary to this
pin if REFA is a single-ended input and REFAA is not used. If dc-coupled, the input
is single-ended 1.8 V CMOS.
47
REFA
Input
1.8 V single-
ended or
differential
input
Reference A Input. This internally biased input is typically ac-coupled; when
configured in this manner, it can accept any differential signal with a single-ended
swing up to the VDD power supply. If dc-coupled, the input can be LVDS or single-
ended 1.8 V CMOS.
48 RESETB Input 1.8 V CMOS
logic
Active Low Chip Reset. This pin has an internal 100 kΩ pull-up resistor. When
asserted, the chip goes into reset. Changes to the VDDIOA supply voltage affect the
V
IH
values for this pin.
EP EPAD Output Exposed
pad
Exposed Pad. The exposed pad is the ground connection on the chip. The exposed
pad must be soldered to the analog ground of the PCB to ensure proper functionality
and for heat dissipation, noise, and mechanical strength benefits.
Data Sheet AD9542
Rev. 0 | Page 21 of 61
TYPICAL PERFORMANCE CHARACTERISTICS
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 224f s
PHASE NO ISE (dBc /Hz):
10Hz –81
100Hz –98
1kHz –118
10kHz –128
100kHz –134
1MHz –144
10MHz –158
>30MHz –159
FLOOR –161
fOUT = 155. 52M Hz
15826-201
Figure 3. Absolute Phase Noise (PLL0, Configuration 1, HCSL Mode,
fREF = 38.88 MHz, fOUT = 155.52 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 220f s
PHASE NO ISE (dBc /Hz):
10Hz –77
100Hz –93
1kHz –114
10kHz –125
100kHz –130
1MHz –140
10MHz –156
>30MHz –158
FLOOR –161
fOUT = 245. 76M Hz
15826-202
Figure 4. Absolute Phase Noise (PLL0, Configuration 2, HCSL Mode,
fREF = 30.72 MHz, fOUT = 245.76 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FREQUENCY ( Hz )
INT EGRATED RMS J ITTER
(12kHz TO 20M Hz): 234.5f s
PHASE NO ISE (dBc /Hz):
10Hz –74
100Hz –89
1kHz –108
10kHz –119
100kHz –123
1MHz –134
10MHz –152
>30MHz –155
FLOOR –159
f
OUT
= 491.52MHz
15826-203
Figure 5. Absolute Phase Noise (PLL0, Configuration 3, HCSL Mode,
fREF = 1 Hz, fOUT = 491.52 MHz, fCOMP = 19.2 MHz TCXO, fSYS = 52 MHz Crystal,
50 MHz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 213f s
PHASE NO ISE (dBc /Hz):
10Hz –84
100Hz –106
1kHz –120
10kHz –131
100kHz –136
1MHz –147
10MHz –160
>30MHz –160
FLOOR –163
fOUT = 125. 0M Hz
15826-204
Figure 6. Absolute Phase Noise (PLL0, Configuration 4, HCSL Mode,
fREF = 125 MHz, fOUT = 125.0 MHz, fCOMP = 19.2 MHz TCXO, fSYS = 52 MHz Crystal,
0.1 Hz DPLL BW, Phase Buildout Mode)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 217f s
PHASE NO ISE (dBc /Hz):
10Hz –74
100Hz –91
1kHz –112
10kHz –123
100kHz –128
1MHz –138
10MHz –154
>30MHz –157
FLOOR –161
fOUT
= 312. 5M Hz
15826-205
Figure 7. Absolute Phase Noise (PLL0, Configuration 5, HCSL Mode,
fREF = 25 MHz, fOUT = 312.5 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW,
Phase Buildout Mode)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 230f s
PHASE NO ISE (dBc /Hz):
10Hz –82
100Hz –99
1kHz –117
10kHz –127
100kHz –133
1MHz –143
10MHz –157
>30MHz –158
FLOOR –160
fOUT = 174. 7M Hz
15826-206
Figure 8. Absolute Phase Noise (PLL0, Configuration 6, HCSL Mode,
fREF = 155.52 MHz, fOUT = 174.7 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW,
Phase Buildout Mode)
AD9542 Data Sheet
Rev. 0 | Page 22 of 61
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 255f s
PHASE NO ISE (dBc /Hz):
10Hz –81
100Hz –98
1kHz –118
10kHz –128
100kHz –132
1MHz –143
10MHz –158
>30MHz –160
FLOOR –162
fOUT = 155. 52M Hz
15826-207
Figure 9. Absolute Phase Noise (PLL1, Configuration 1, HCSL Mode,
fREF = 38.88 MHz, fOUT = 155.52 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 280f s
PHASE NO ISE (dBc /Hz):
10Hz –76
100Hz –93
1kHz –114
10kHz –124
100kHz –127
1MHz –138
10MHz –156
>30MHz –159
FLOOR –161
fOUT = 245. 76M Hz
15826-208
Figure 10. Absolute Phase Noise (PLL1, Configuration 2, HCSL Mode,
fREF = 30.72 MHz, fOUT = 245.76 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 322. 7f s
PHASE NO ISE (dBc /Hz):
10Hz –74
100Hz –90
1kHz –108
10kHz –118
100kHz –120
1MHz –131
10MHz –150
>30MHz –154
FLOOR –160
fOUT = 491. 52M Hz
15826-209
Figure 11. Absolute Phase Noise (PLL1, Configuration 3, HCSL Mode,
fREF = 1 Hz, fOUT = 491.52 MHz, fCOMP = 19.2 MHz TCXO, fSYS = 52 MHz Crystal,
50 MHz DPLL BW)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 243f s
PHASE NO ISE (dBc /Hz):
10Hz –83
100Hz –106
1kHz –120
10kHz –131
100kHz –135
1MHz –145
10MHz –160
>30MHz –160
FLOOR –163
fOUT = 125. 0M Hz
15826-210
Figure 12. Absolute Phase Noise (PLL1, Configuration 4, HCSL Mode,
fREF = 125 MHz, fOUT = 125 MHz, fCOMP = 19.2 MHz TCXO, fSYS = 52 MHz
Crystal, 0.1 Hz DPLL BW, Phase Buildout Mode)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 266f s
PHASE NO ISE (dBc /Hz):
10Hz –73
100Hz –91
1kHz –112
10kHz –122
100kHz –125
1MHz –137
10MHz –154
>30MHz –158
FLOOR –161
fOUT
= 312. 5M Hz
15826-211
Figure 13. Absolute Phase Noise (PLL1, Configuration 5, HCSL Mode,
fREF = 25 MHz, fOUT = 312.5 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW,
Phase Buildout Mode)
–170
–160
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
10 100 1k 10k 100k 1M 10M 100M
PHASE NOISE (dBc/Hz)
FRE QUENCY ( Hz )
INT EGRATED RMS J ITT ER
(12kHz TO 20M Hz) : 264f s
PHASE NO ISE (dBc /Hz):
10Hz –77
100Hz –99
1kHz –117
10kHz –127
100kHz –131
1MHz –142
10MHz –158
>30MHz –159
FLOOR –161
fOUT = 174. 7M Hz
15826-212
Figure 14. Absolute Phase Noise (PLL1, Configuration 6, HCSL Mode,
fREF = 155.52 MHz, fOUT = 174.7 MHz, fSYS = 52 MHz Crystal, 50 Hz DPLL BW,
Phase Buildout Mode)
Data Sheet AD9542
Rev. 0 | Page 23 of 61
0
100
200
300
400
500
600
700
800
00.2 0.4 0.6 0.8 1.0
TIME (Seconds)
1.2 1.4 1.6 1.8 2.0
7. 5 m A MODE
15m A MODE
VOLTAGE (mV)
15826-040
Figure 15. DC-Coupled, Single-Ended, 1 Hz Output Waveforms Using HCSL
7.5 mA and 15 mA Mode Terminated 50 Ω to GND per Figure 38;
Slew Rate: ~7 V/ns for 15 mA Mode; ~3.5 V/ns for 7.5 mA Mode
–1.2
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
050 100 150 200 250 300 350 400
TIME (μs)
HCSL, 7. 5mA ( S LEW RAT E ~ 2.4V/ns)
CML, 7. 5mA ( S LEW RAT E ~ 2.7V/n s)
HCSL, 15mA (S LEW RAT E ~ 5.4V/ns)
CML, 15mA (S LEW RAT E ~ 6V /n s)
DIFFERENTIAL PEAK-TO-PEAK
VOLTAGE SWING (V p-p )
15826-035
Figure 16. 8 kHz Output Waveforms for Various Driver Settings;
HCSL Drivers Terminated 50 Ω to GND per Figure 32;
CML Drivers Terminated 50 Ω to 1.8 V per Figure 33
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
020 40 60 80 100 120 140 160 180 200
TIME ( ns)
DIFFERENTIAL PEAK-TO-PEAK
VOLTAGE SWING (V p-p )
HCSL, 7. 5mA, 10MHz
CML, 7. 5mA, 10MHz HCSL, 15mA, 10M Hz
CML, 15mA, 10M Hz
15826-036
Figure 17. 10 MHz Output Waveforms for Various Driver Settings;
HCSL Drivers Terminated 50 Ω to GND per Figure 32;
CML Drivers Terminated 50 Ω to 1.8 V per Figure 33
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
012345678910
DIFFERENTIAL PEAK-TO-PEAK
VOLTAGE SWING (V p-p)
TIME (ns)
HCSL, 15mA
CML, 15mA
15826-037
Figure 18. 245.76 MHz Output Waveform for 15 mA Driver Settings;
HCSL Drivers Terminated 50 Ω to GND per Figure 32;
CML Drivers Terminated 50 Ω to 1.8 V per Figure 33
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
1.0
012 3 45678910
DIFFERENTIAL PEAK-TO-PEAK
VOLTAGE SWING (V p-p )
TIME (ns)
HCSL, 15mA
CML, 15mA
15826-038
Figure 19. 491.52 MHz Output Waveform for15 mA Driver Settings;
HCSL Drivers Terminated 50 Ω to GND per Figure 32;
CML Drivers Terminated 50 Ω to 1.8 V per Figure 33
0
200
400
600
800
1000
1200
1400
1600
1800
2000
110 100 1k 10k 100k 1M 10M 100M 1G
DIFFERENTIAL PEAK-TO-PEAK
VOLTAGE SWING (mV p-p)
FREQUENCY (Hz)
CML, DIFFERENTIAL, 15mA
CML, DIFFERENTIAL, 12.5mA
CML, DIFFERENTIAL, 7.5mA
HCSL, DI FF E RE NTI AL, 15mA
HCSL, DI FF E RE NTI AL, 12.5mA
HCSL, DIFFERENTIAL, 7.5mA
15826-039
Figure 20. Differential Output Amplitude Waveforms;
HCSL Drivers Terminated 50 Ω to GND per Figure 32;
CML Drivers Terminated 50 Ω to 1.8 V per Figure 33
AD9542 Data Sheet
Rev. 0 | Page 24 of 61
–30
–25
–20
–15
–10
–5
0
5
0.001 0.01 0.1 110 100 1k
PHASE M ARGIN: 88 .5°
PEAKING: <0.1dB
ATTENUATION:
AT LOOP BW: 5.5dB
2× LOOP BW : 18dB/ DECADE
100 × L OOP BW: 41dB/ DE CADE
1000× LOO P BW: 60dB/ DECADE
OFFSET FREQUENCY (Hz)
BW = 1 0 m Hz
BW = 100mHz
BW = 1 Hz
BW = 1 0 Hz
BW = 100Hz
CLOSED-LOOP GAIN (dB)
15826-041
Figure 21. DPLL Closed-Loop Transfer Function Nominal Phase Margin
Loop Filter Setting
–30
–25
–20
–15
–10
–5
0
5
0.001 0.01 0.1 1
OFF SET F REQUENCY (Hz)
10 100 1000
PHASE M ARGIN: 7 0°
PEAKING: 1.07dB
ATTENUATION:
AT LOOP BW: 2.5dB
2× LOO P BW: 21dB/
DECADE
100× LOO P BW: 60dB/
DECADE
CLOSED-LOOP GAIN (dB)
15826-042
BW = 1 0 m Hz
BW = 100mHz
BW = 1 Hz
BW = 1 0 Hz
BW = 100Hz
Figure 22. DPLL Closed-Loop Transfer Function High Phase Margin Loop
Filter Setting
Data Sheet AD9542
Rev. 0 | Page 25 of 61
TERMINOLOGY
Zero Delay
Zero delay is seen in an integer-N PLL architecture that establishes
zero (or nearly zero, but constant) phase offset between the final
output signal and the signal appearing at the reference input of
the PLL phase detector. A PLL with zero delay provides minimal
input to output phase offset in the static (steady state) sense.
That is, phase slewing at the output typically occurs any time
the PLL is in the process of phase or frequency acquisition (for
example, when a multiple input PLL switches from one input
reference signal to another).
Hitless Switchover
Hitless switchover applies to PLLs with the ability to switch
from one reference signal to another while maintaining a
constant phase relationship from the active input to output.
Hitless switchover is the ability of a PLL to switch between
reference signals having an arbitrary initial instantaneous
phase offset. In hitless switching, the output signal slews in a
prescribed manner from its initial phase to the new phase, and
the absolute phase relationship from active input to output is
maintained. The reference switching scheme is hitless if the
phase slewing is gradual enough to not cause traffic hits caused
by the output clock phase slewing. A PLL employing hitless
switchover capability requires the output/input frequency ratio
to be an integer greater than or equal to 1. Hitless output phase
transient limitation applies any time the PLL is in the process of
phase or frequency acquisition (that is, it is not necessarily
limited to reference switching).
Phase Buildout (PBO) Switchover
PBO only applies to PLLs with the ability to switch from
one reference signal to another. PBO is the ability of a PLL to
switch between two reference signals having an arbitrary initial
instantaneous phase offset, whereby the phase of the output
signal remains fixed. This mode of operation implies the ability
of the PLL to absorb the phase difference between the two
reference input signals, the goal being to prevent a phase
disturbance at the output when switching between two
reference signals. Prevention of a phase disturbance at the
output means there is no guarantee of phase alignment between
the input and output signals. Unlike hitless switchover, PBO
places no restriction on the output/input frequency ratio. PBO
output phase transient prevention applies any time the PLL is in
the process of phase or frequency acquisition (that is, it is not
necessarily limited to reference switching).
For more information, see the AN-1420 Application Note, Phase
Buildout and Hitless Switchover with Digital Phase-Locked Loops
(DPLLs).
AD9542 Data Sheet
Rev. 0 | Page 26 of 61
THEORY OF OPERATION
OVERVIEW
The AD9542 provides clocking outputs that are directly related
in phase and frequency to the selected (active) reference but
with jitter characteristics governed by the system clock, the
DCO, and the analog output PLL (APLL). The AD9542 supports
up to four reference inputs and input frequencies ranging from
2 kHz to 750 MHz. The cores of this device are two DPLLs.
Each DPLL has a programmable digital loop filter that greatly
reduces jitter transferred from the active reference to the output,
and these four DPLLs operate completely independently of each
other. The AD9542 supports both manual and automatic
holdover. While in holdover, the AD9542 continues to provide an
output as long as the system clock is present. The holdover
output frequency is a time average of the output frequency
history prior to the transition to the holdover condition. The
device offers manual and automatic reference switchover
capability if the active reference is degraded or fails completely.
The AD9542 includes a system clock multiplier and two DPLLs,
each cascaded with its own APLL.
The input signal goes first to the DPLL, which performs the
jitter cleaning and most of the frequency translation. Each DPLL
features a 48-bit DCO output that generates a signal in the range
of 162 MHz to 350 MHz.
The DCO output goes to the APLL, which multiplies the signal
up to a range of 2.424 GHz to 3.232 GHz (for Channel 0) or
3.232 GHz to 4.040 GHz (for Channel 1). After division by 2, this
signal is sent to the clock distribution section, which consists of
the 32-bit Q divider and output driver for each output. Channel 0
has six Q dividers and Channel 1 has four Q dividers.
The XOA and XOB inputs provide the input for the system clock.
These pins accept a reference clock in the 20 MHz to 300 MHz
range or a 25 MHz to 52 MHz crystal connected directly across
the XOA and XOB inputs. The system clock provides the clocks to
the frequency monitors, the DPLLs, and internal switching logic.
The AD9542 has five differential output drivers. Each of the five
output drivers has a dedicated 32-bit programmable Q divider.
Each differential driver operates up to 500 MHz and is configura-
ble as a CML driver with external pull-up resistors, or an HCSL
driver with external pull-down resistors. There are three drive
strengths:
• The 7.5 mA mode is used for CML and HCSL and
ac-coupled LVDS. When used as an LVDS-compatible
driver, it must be ac-coupled and terminated with a 100 Ω
resistor across the differential pair.
• The 15 mA mode produces a voltage swing and is compatible
with LVPECL. If LVPECL dc signal levels are required, the
designer must ac couple and rebias the AD9542 output.
The 15 mA mode can also be used with the termination
scheme shown in Figure 34 and Figure 35 to produce an
LVDS signal with the correct LVDS dc bias.
• The 12 mA mode is halfway in between the two other settings.
REFERENCE INPUT PHYSICAL CONNECTIONS
Two pairs of pins (REFA/REFAA and REFB/REFBB) provide
access to the reference clock receivers. The user can reconfigure
each differential pair into two single-ended reference inputs. To
accommodate input signals with slow rising and falling edges,
both the differential and single-ended input receivers employ
hysteresis. Hysteresis also ensures that a disconnected or
floating input does not cause the receiver to oscillate.
When configured for differential operation, the input receivers
accommodate either ac-coupled or dc-coupled input signals.
If the input receiver is configured for dc-coupled LVDS mode,
the input receivers are capable of accepting dc-coupled LVDS
signals. The receiver is internally dc biased to handle ac-coupled
operation; however, there is no internal 50 Ω or 100 Ω termination.
Data Sheet AD9542
Rev. 0 | Page 27 of 61
INPUT/OUTPUT TERMINATION RECOMMENDATIONS
SYSTEM CLOCK INPUTS
XOA
XOB
AD9542
10MHz TO 50MHz FUNDAMENTAL
AT-CUT CRYSTAL WITH 10pF
LOAD CAPACITANCE (C
LOAD
)
15pF
15pF
15826-018
Figure 23. System Clock Input (XOA/XOB) in Crystal Mode (Each 15 pF Shunt
Capacitor Shown Must Equal 2× (CLOAD − CSTRAY,
Where Typical CSTRAY = 2 pF to 5 pF)
XOA
330
150
0.1µF
XOB
AD9542
3.3V
CMOS
TCXO
0.1µF
15826-019
Figure 24. System Clock Input (XOA, XOB) when Using a TCXO/OCXO with
3.3 V CMOS Output
REFERENCE CLOCK INPUTS
R1
R2
REFx
OR
REFxx
INTERNAL DC THRESHOLD
FOR 1.2V OR 1.8V CMOS
AD9542
1.8V RECEIVER
CMOS
DRIVER
HI-Z
INPUT
15826-020
Figure 25. Single-Ended DC-Coupled Mode, 1.2 V or 1.8 V CMOS
R
L
(OPTIONAL)
0.1µF
REFx
OR
REFxx AD9542
1.8V RECEIVER
DRIVER
1.2V
47k
47k
0.6V
15826-021
Figure 26. Single-Ended AC-Coupled Mode
REFx
OR
REFxx
AD9542
DRIVER
1.2V
47k
0.6V
15826-022
Figure 27. Single-Ended Internal Pull-Up Mode
REFx
LVDS DRIVER
(1.2V COMMON-MODE)
REFxx
AD9542
100
20µA
20µA
20µA
20µA
1.2V
30k
30k
LEVEL SHIFT
15826-023
Figure 28. Differential LVDS Input Mode
REFx
DIFFERENTIAL
DRIVER
REFxx
AD9542
R
L
4747
0.6V
0.1µF
0.1µF
1.2V
0.6V
4747
15826-024
Figure 29. Differential AC-Coupled Mode (RL = 100 Ω Is Recommended,
Except For HCSL)
REFx
DIFFERENTIAL DRIVER
(0.6V COMMON-MODE)
REFxx
AD9542
R
L
15826-025
Figure 30. Differential DC-Coupled Mode
AD9542 Data Sheet
Rev. 0 | Page 28 of 61
CLOCK OUTPUTS
AD9542
I
I
PLLx +1.8V
Q
XY
Q
XYY
I-SOURCE MODE
OUTxyP
OUTxyN
50Ω
100Ω
50Ω
0.1µF
0.1µF
LVDS OR
LVPECL
RECEIVER
LVDS: USE 7.5mA DRIVER SETTING.
LVPECL: USE 15mA DRIVER SETTING.
15826-027
Figure 31. LVDS-Compatible Output Swing, AC-Coupled (V p-p ≈ 375 mV per Section for I = 15 mA
AD9542
I
I
PLLx +1.8V
Q
XY
Q
XYY
I-SOURCE MODE
OUTxyP
OUTxyN
50Ω
50Ω
TO HCSL
RECEIVER
15826-026
Figure 32. HCSL Output, V p-p ≈ 750 mV per Section (I = 15 mA)
AD9542
I
I
PLLx
Q
XY
Q
XYY
I-SINK MODE
OUTxyP
OUTxyN
50Ω
50Ω
1.2V, 1.5V
OR 1.8V
15826-028
Figure 33. CML Output (I = 7.5 mA; I = 15 mA Options for 1.5 V or 1.8 V Supply)
AD9542
I
I
PLLx
Q
XY
Q
XYY
I-SINK MODE
OUTxyP
OUTxyN
50Ω
50Ω
50Ω
1.8V
10nF
R
L
15826-029
Figure 34. LVDS-Compatible Output, 1.24 V Common-Mode, T Network
(I = 7.5 mA; I = 15 mA with Extra 100 Ω Termination, RL)
AD9542
I
I
PLLx
Q
XY
Q
XYY
I-SINK MODE
OUTxyP
OUTxyN
1.8V R
L
63.4Ω237Ω
63.4Ω237Ω
15826-030
Figure 35. LVDS-Compatible Output, 1.2 V Common-Mode, Thevenin Bias
Network (I = 7.5 mA; 15 mA With Extra 100 Ω Termination, RL)
AD9542
I
I
PLLx
QXY
QXYY
I-SINK MODE
OUTxyP
OUTxyN
1.8V
56.2Ω453Ω
56.2Ω453Ω
15826-031
Figure 36. 2.5 V LVPECL or Double Amplitude LVDS-Compatible Boost
Output, 1.5 V p-p, 1.24 V Common-Mode (I = 15 mA)
AD9542
I
I
PLLx
Q
XY
Q
XYY
I-SOURCE MODE
OUTxyP
OUTxyN
+1.8V IN PHASE
OUTPUTS
R
L
R
L
15826-032
Figure 37. Single-Divider, Single-Ended Mode Providing In-Phase Outputs
(Current Source Mode)
AD9542
I
I
PLLx
QXY
QXYY
I-SOURCE MODE
OUTxyP
OUTxyN
+1.8V INDEPENDENT
OUTPUTS
RL
RL
15826-033
Figure 38. Dual-Divider, Single-Ended Mode Providing Independent Outputs
(Current Source Mode); Note that Single-Ended CML Mode Is Also Available
(See Figure 33)
Data Sheet AD9542
Rev. 0 | Page 29 of 61
SYSTEM CLOCK PLL
Note that throughout the System Clock PLL section, unless
otherwise specified, any referenced bits, registers, or bit fields
reside in the system clock (SYSCLK) section of the register map
(Register 0x0200 to Register 0x0209).
The system clock PLL (see Figure 39) comprises an integer-N
frequency synthesizer with a fully integrated loop filter and voltage
controlled oscillator (VCO). The VCO output is the AD9542
system clock with a frequency range of 2250 MHz to 2415 MHz.
The XOA and XOB pins constitute the input to the system clock
PLL to which a user connects a clock source or crystal resonator.
VCO
CALIBRATION
LOCK
DETECTOR
SYSTEM
CLOCK
XOA
XTAL
DIRECT
2250MHz TO
2415MHz
XOB
2×
÷J
÷K
1, 2, 4, 8
4 TO 255
PFD,
CHARGE P UM P ,
LOO P FI LTER
AD9542
15826-309
Figure 39. System Clock PLL Block Diagram
SYSTEM CLOCK INPUT FREQUENCY
DECLARATION
Proper operation of the AD9542 requires the user to declare
the input reference frequency to the system clock PLL. To do
so, program the SYSCLK reference frequency bit field, which
constitutes the nominal frequency of the system clock PLL
input reference. The AD9542 evaluation software frequency
planning wizard calculates this value for the user.
SYSTEM CLOCK SOURCE
The XOA and XOB pins serve as the input connection to the
system clock PLL, giving the user access to a crystal path or a
direct path. Path selection is via the enable maintaining
amplifier bit, where a Logic 0 (default) selects the direct path
and Logic 1 selects the crystal path. The optimal reference
source for the system clock input is a crystal resonator in the
50 MHz range or an ac-coupled square wave source (single-
ended or differential) with 800 mV p-p amplitude.
Crystal Path
The crystal path supports crystal resonators in the 25 MHz to
60 MHz frequency range. An internal maintaining amplifier
provides the negative resistance required to induce oscillation. The
internal amplifier expects an AT cut, fundamental mode crystal
with a maximum motional resistance of 100 Ω for crystals up to
52 MHz, and 50 Ω for crystals up to 60 MHz. The following
crystals, listed in alphabetical order, may meet these criteria.
• AVX/Kyocera CX3225SB
• ECS, Inc. ECX-32
• Epson/Toyocom TSX-3225
• Fox FX3225BS
• NDK NX3225SA
• Siward SX-3225
• Suntsu SCM10B48-49.152 MHz
Analog Devices, Inc., does not guarantee the operation of the
AD9542 with the aforementioned crystals, nor does Analog
Devices endorse one crystal supplier over another. The AD9542
reference design uses a readily available high performance
49.152 MHz crystal with low spurious content.
Direct Path
The direct path has a differential receiver with a self bias of
0.6 V dc. Generally, the presence of the bias voltage necessitates
the use of ac coupling between the external source and the XOA
and XOB pins. Furthermore, when using a 3.3 V CMOS oscillator
as the system clock PLL reference source, in addition to ac
coupling, it is important to use a voltage divider to reduce the
3.3 V swing to a maximum of 1.14 V (note that the optimal
voltage swing is 800 mV p-p). The external signal must exhibit a
50% duty cycle for best performance.
The direct path supports low frequency LVPECL, LVDS,
CMOS, or sinusoidal clock sources as a reference to the system
clock PLL. For a sinusoidal source, however, it is best to use a
frequency of 50 MHz or greater. The low slew rate of lower
frequency sinusoids tends to yield nonoptimal noise performance.
Applications requiring low DPLL loop bandwidth require the
improved stability provided by a TCXO or OCXO. Loop
bandwidths below approximately 50 Hz may prevent the PLL
from locking or cause random loss of lock events when using a
less stable PLL reference source.
Although one method to mitigate this problem is to use a high
stability system clock source (like an OCXO), the AD9542
provides integrated system clock compensation capability,
which lessens the stability requirement on the system clock
while providing the outstanding phase noise of the higher
frequency crystal. To use this feature, connect a 40 MHz to
60 MHz crystal to the XOA/XOB pins (as in Figure 23), and
connect either a TCXO or OCXO to either an unused reference
input or an Mx pin (as shown in Figure 24).
2× FREQUENCY MULTIPLIER
The system clock PLL provides the user with the option of
doubling the reference frequency via the enable SYSCLK
doubler bit. Doubling the input reference frequency potentially
reduces the PLL in-band noise. The reference frequency must be
less than 150 MHz when using the 2× frequency multiplier to
satisfy the 300 MHz maximum PFD rate. Furthermore, the 2×
frequency multiplier requires the reference input signal to have
very near to 50% duty cycle; otherwise, the resulting spurious
content may prevent the system clock PLL from locking.
PRESCALE DIVIDER
The system clock PLL includes an input prescale divider
programmable for divide ratios of 1 (default), 2, 4, or 8. The
purpose of the divider is to provide flexible frequency planning
for mitigating potential spurs in the output clock signals of the
AD9542. The user selects the divide ratio via the 2-bit SYSCLK
AD9542 Data Sheet
Rev. 0 | Page 30 of 61
input divider ratio bit field. The corresponding divide value is
2J, where J is the decimal value of the 2-bit number in the SYSCLK
input divider ratio bit field.
For example, given that the SYSCLK input divider ratio bit field is
10 (binary), J = 2 (decimal), yielding a divide ratio of 2J = 22 = 4.
FEEDBACK DIVIDER
The output of the system clock PLL constitutes the system clock
frequency, fS. The system clock frequency depends on the value
of the feedback divider. The feedback divide ratio has a range of
4 to 255, which the user programs via the 8-bit feedback divider
ratio register (the register value is the divide ratio). For example,
a programmed value of 100 (0x64 hexadecimal) yields a divide
ratio of 100.
SYSTEM CLOCK PLL OUTPUT FREQUENCY
Calculate the system clock frequency as follows:
J
K
ff SYSINS×=
where:
fSYSIN is the input frequency.
K is the feedback divide ratio.
J is the input divide ratio. J = ½ when using the 2× frequency
multiplier.
The user must choose fSYSIN, K, and J such that fS satisfies the
VCO range of 2250 MHz to 2415 MHz.
SYSTEM CLOCK PLL LOCK DETECTOR
The system clock PLL features a simple lock detector that
compares the time difference between the reference and
feedback clock edges. The user can check the status of the lock
detector via the SYSCLK locked bit in the status readback
registers (Address 0x3000 to Address 0x300A) of the register
map, where Logic 1 indicates locked and Logic 0 unlocked. The
most common reason the system clock PLL fails to lock is due
to the user employing the 2× frequency multiplier with a
reference input clock that deviates from the 50% duty cycle.
SYSTEM CLOCK STABILITY TIMER
Because time processing blocks within the AD9542 depend on
the system clock generating a stable frequency, the system clock
PLL provides an indication of its status. The status of the system
clock PLL is available to the user as well as directly to certain
internal time keeping blocks.
At initial power-up, the system clock status is unknown and
reported as being unstable. However, after the user programs
the system clock registers and the system clock PLL VCO
calibrates, the system clock PLL locks shortly thereafter.
SYSTEM CLOCK INPUT TERMINATION
RECOMMENDATIONS
To connect a crystal resonator to the system clock PLL XOA
and XOB inputs, refer to Figure 23. Be sure to program the
enable maintaining amplifier bit = 1 to select the crystal path.
The 15 pF shunt capacitors shown relate to the CLOAD and CS TRAY
associated with the crystal as follows:
CSHUNT = 2 × (CLOAD – CSTRAY)
For CLOAD = 10 pF and CSTRAY = 2 pF to 5 pF, the value of CSHUNT
is approximately 15 pF.
To connect a TCXO or OCXO with a 3.3 V output, refer to
Figure 24. Be sure to program the enable maintaining amplifier
bit = 0 to select the direct path.
Data Sheet AD9542
Rev. 0 | Page 31 of 61
DIGITAL PLL (DPLL)
OVERVIEW
Note that throughout this section, unless otherwise specified,
any referenced bits, registers, or bit fields reside in the DPLL
Channel 0 and DPLL Channel 1 sections (Address 0x1000 to
Address 0x102A, and Address 0x1400 to Address 0x142A) of
the register map.
The DPLL is an all-digital implementation of a phase-locked
loop (PLL). Figure 40 shows the fundamental building blocks of
an APLL and a DPLL. An APLL typically relies on a VCO as the
frequency element for generating an output signal, where the
output frequency depends on an applied dc voltage. A DPLL, on
the other hand, uses a numerically controlled oscillator (NCO),
which relies on a digital frequency tuning word (FTW) to
produce the output frequency. A VCO inherently produces a
timing signal because it is, by definition, an oscillator, whereas
the AD9542 NCO requires an external timing source, the system
clock. The fundamental difference between an APLL and a
DPLL is that the VCO in an APLL can tune to any frequency
within its operating bandwidth, whereas the NCO in a DPLL
can only tune to discrete frequencies (by virtue of the FTW).
PHASE
DETECTOR
DIVIDER
LOOP
FILTER
VCO
ANALOG
PHASE
ERROR VOLTAGE
FIXED LOOP
BANDWIDTH
APLL
DIGITAL
PHASE
DETECTOR
DIVIDER
DIGITAL
LOOP
FILTER
NUMERIC
PHASE
ERROR
SYSTEM
CLOCK
PROGRAMMABLE
LOOP BANDWI DTH
DPLL
NCO
NUMERIC
COEFFICIENTS
NUMERIC
FREQUENCY
TUNING WO RD
15826-312
Figure 40. APLL vs. DPLL
The DPLLs in the AD9542 have a digital TDC-based phase
detector and a digital loop filter with programmable bandwidth.
The digital loop filter output yields a digital FTW (instead of a
dc voltage, as in the case of an analog PLL) that produces a
corresponding NCO output frequency.
DPLL PHASE/FREQUENCY LOCK DETECTORS
See the Lock Detectors section for details concerning the phase
and frequency detectors of the DPLL.
DPLL LOOP CONTROLLER
The DPLL has several operating modes (including freerun,
holdover, and active). To ensure seamless transition between
modes, the DPLL has a loop controller. The loop controller sets
the appropriate DPLL operating mode based on the prevailing
requirements of automatic reference switching or manual
control settings.
Switchover
Switchover occurs when the loop controller switches directly
from one input reference to another. The AD9542 handles a
reference switchover by briefly entering holdover mode, loading
the new DPLL parameters, and then immediately recovering.
Holdover
Typically, the holdover state is in effect when all of the input
references are invalid. However, the user can force the holdover
mode even when one or more references are valid by setting the
DPLLx force holdover bit (where x = 0 or 1) in the Operational
Control Channel 0 and Operational Control Channel 1 sections
of the register map to Logic 1. In holdover mode, the output
frequency remains fixed (to the extent of the stability of the
system clock). The accuracy of the AD9542 in holdover mode is
dependent on the device programming and availability of the
tuning word history.
Recovery from Holdover
When in holdover and an enabled translation profile becomes
available, the device exits holdover operation. The loop controller
restores the DPLL to closed-loop operation, locks to the selected
reference, and sequences the recovery of all the loop parameters
based on the profile settings for the active reference.
If the DPLLx force holdover bit (where x = 0 or 1) in the
Operational Control Channel 0 and Operational Control
Channel 1 sections of the register map is set to Logic 1, the
device does not automatically exit holdover when a valid
translation profile is available. However, automatic recovery can
occur after clearing the DPLL force holdover bit.
AD9542 Data Sheet
Rev. 0 | Page 32 of 61
APPLICATIONS INFORMATION
OPTICAL NETWORKING LINE CARD
In this application (shown in Figure 41), the AD9542 is used in
a variety of ways.
In a loop timed (WAN) mode, one of the AD9542 DPLLs locks
to the CDR and is used to remove jitter on the receiver path,
sending that clock to the central timing card, as well as the
framer. In some applications, the AD9542 can also perform a
variety of frequency translation tasks, such as multiplying or
dividing by an FEC ratio, and/or removing jitter from a gapped
clock. The other DPLL cleans jitter and provides clocking to the
transmitter path.
Other tasks include frequency translation and jitter cleaning of
the reference clock from the timing card, as well as seamlessly
managing the reference switching from Timing Card A to
Timing Card B.
Given the continually evolving nature of optical line card
protocols and functions, the functions listed in this section are
by no means exhaustive.
FRAMER/FEC DESERIALIZER CDR
FRAMER/FEC SERIALIZER
BACKPLANE
LDD
LASER DIODE
POST
AMP TIA PHOTO DIODE
Tx
Rx
LINE CARD OPTICAL MODULE
TO SDH/PDH
OPTICAL
NETWORK
AD9542
FROM TIMING CARD B
FROM TIMING CARD A
15826-043
Figure 41. Optical Line Card Example
Data Sheet AD9542
Rev. 0 | Page 33 of 61
SMALL CELL BASE STATION
In this application (shown in Figure 42), the AD9542 provides
all of the synchronization to the baseband unit of a small cell
base station. The built in JESD204B support enables a particu-
larly compact and efficient design.
The AD9542 can lock to any of the following: GPS, SyncE,
and/or IEEE1588 (requires a separate IEEE1588 servo and
software stack) or loop timed (if using SONET/SDH backhaul).
The PLL0 of the AD9542 provides one device clock and up to
four device system reference clocks that can be used to clock
wireless transceivers, such as the AD9371.
The PLL1 of the AD9542 clocks the backhaul interface and,
optionally, the CPU interface.
The EEPROM support of the AD9542 allows the AD9542 to
load its configuration automatically at power-up.
BASEBAND
PROCESSOR
UP TO TWO
RADIO CARDS
(INCLUDI NG AD9371
TRANSCEIVER)
NETWORK
CONNECTION
INPUT
LOOP-TIMED/SyncE
FROM NETWORK
30.72MHz/
61.44MHz/
122.88MHz
WI TH JES D204B
SUPPORT
30.72MHz/61.44MHz/
122.88MHz/245.76MHz/
307.2MHz
DIFF/SE OUTPUTS
<300fs OF JITTER
10 MHz/ 25M Hz /
125 MHz/ 156.25MHz /
312.5MHz DIF F/S E
OUTPUTS
<300fs OF JITTER
EXTERNAL
NETWORK
CONNECTION
ETHERNET
SyncE
PON
SONET/SDH
SYSREF TO
RADIO 1
SYSREF TO
RADIO 2
SYSREF TO
BASEBAND
CLOCK
MULTIPLIER
CLO CK DRIF T
COMPENSATION
CONTROL
LOGIC
ANALOG
PLL1
DIGITAL
PLL1
PPS
DEMOD
DIVIDERS MONITORS,
CROSS P OI NT MUX
/Q
1B
+ PPS
/Q
1A
+ PPS
/Q
0C
+ PPS
/Q
0B
SYSREF
/Q
0B
SYSREF
/Q
0A
SYSREF
/Q
0A
SYSREF
SERI AL PORT
(SPI OR I
2
C)
CSB, S CLK/ S CL,
SDIO/ S DA, SDO
STATUS AND
CONTROL PINS EEPROM
CONTROLLER
Mx PI NS
DIGITAL
PLL0
PPS
DEMOD
ANALOG
PLL0
MUX MUX
REFA/AA
REFB/BB
AD9542
NEXT GENE RATION SY NCHRONIZER
1:4
FANOUT
EXTERNAL
EEPROM
(OPTIONAL)
15826-044
Figure 42. Small Cell Application
AD9542 Data Sheet
Rev. 0 | Page 34 of 61
INITIALIZATION SEQUENCE
Figure 43, Figure 44, and Figure 45 describe the sequence for powering on and programming the AD9542.
WRITE:
REGISTER 0x000F = 0x01
ISSUE A
CHIP LEVEL RESET
(PIN OR SOFT RESET)
RST_COUNT =
RST_COUNT + 1
APPLY VDD
(ALL DOMAINS)
START
VDD
SETTLED?
REFERENCE INPUT(S)
CAN BE APPLIED
ANY TIME HEREAFTER
SUB-PROCESS:
SYSTEM CLOCK
INITIALIZATION
POR: WAIT 60ms
RST_COUNT > 0
RAISE FLAG FOR
DEBUGGING
WRITE:
REGISTER 0x000F = 0x01
READ:
REGISTER 0x3000 TO REGISTER 0x3019
REGISTER 0x3100 TO REGISTER 0x310E
REGISTER 0x3200 TO REGISTER 0x320E
END
RST_COUNT = 0
YES
NO
NO
YES
CHIP LEVEL
RESET LOOP
WAIT FOR POWER
SUPPLIES TO
STABILIZE
SUB-PROCESS:
ANALOG PLLi
INITIALIZATION
i = 0
APLLi
ENABLED
i > 1
i = i +1
NO
NO
YES
SOFTWARE
GENERATED
AD9542
REGISTER DUMP
WRITE REGISTER
CONTENT FROM
SETUP FILE
YES
15826-101
Figure 43. Programming Sequence Loop
Data Sheet AD9542
Rev. 0 | Page 35 of 61
CAL_COUNT =
CAL_COUNT + 1
CAL_COUNT = 0
VCO
CALIBRATION
OPERATION
CAL_COUNT > 1
NO
YES
SYSTEM CLOCK
RECALIBRATION LOOP
WRITE:
REGISTER 0x2000[2] = 0
WRITE:
REGISTER 0x000F = 0x01
WRITE:
REGISTER 0x000F = 0x01
WRITE:
REGISTER 0x2000[2] = 1
START TIMEOUT CLOCK:
TIME = 0
REGISTER 0x3001[1:0] = 0x3 TIMEOUT CLOCK:
TIME > SYSCLK_TO1
NO
YES
NO
YES
SYSTEM CLOCK
LOCKED AND
STABLE POLLING LOOP
END
(TO RST_COUNT CHECK)
END
START
1SYSCLK_TO IS A CALCULATED TIME OUT VALUE.
IT IS 50ms + SYSTEM CLOCK VALIDATION TIME (REGISTER 0x0207 TO REGISTER 0x0209 [UNITS OF ms])
15826-102
Figure 44. System Clock Initialization Subprocess
AD9542 Data Sheet
Rev. 0 | Page 36 of 61
START TIMEOUT CLOCK:
TIME = 0
CAL_COUNT = 0
LOCK REG BIT 3 = 1 TIMEOUT CLOCK:
TIME > 50ms
CAL_COUNT > 1
NO
YES
NO
YES
NO
YES
CAL_COUNT =
CAL_COUNT + 1
APLL LOCK
DETECT POLLING
LOOP
APLL RECALIBRATION
LOOP
START
END
END
(TO RST_COUNT
CHECK)
WRITE:
CAL REG BIT 1 = 0
WRITE:
REGISTER 0x000F BIT 0 = 1
WRITE:
REGISTER 0x000F BIT 0 = 1
WRITE:
CAL REG BIT 1 = 1
VCO
CALIBRATION
OPERATION
WRITE:
SYNC REG BIT 3 = 1
WRITE:
REGISTER 0x000F BIT 0 = 1
WRITE:
REGISTER 0x000F BIT 0 = 1
MANUAL
DISTRIBUTION
SYNCHRONIZATION
OPERATION
WRITE:
SYNC REG BIT 3 = 0
AUTO SYNC
REGISTERS[1:0] = 0
NO
YES
CAL REG.
0x2100
0x2200
APLL
0
1
LOCK REG.
0x3100
0x3200
SYNC REG.
0x2101
0x2201
AUTO-SYNC REG.
0x10DB
0x14DB
15826-103
Figure 45. Analog PLL Initialization Subprocess
Data Sheet AD9542
Rev. 0 | Page 37 of 61
STATUS AND CONTROL PINS
Mx PINS
CONTROL
FUNCTION
SELECT
STATUS
SOURCE
SELECT
Mx PIN
CONTROL
REGISTERS
I/O UPDATE
I/O
CONTROL
DEVICE
RESET
POWER UP
AUTOCONFIGURATION
CONTROL
DESTINATIONS
STATUS
SOURCES
Mx PIN FUNCTION LOGIC
LATCHES
LATCHES
15826-104
Figure 46. Mx Pin Logic
The AD9542 features seven independently configurable digital
CMOS status/control pins (M0 to M6). Configuring an Mx pin
as a status pin causes that pin to be an output. Conversely,
configuring an Mx pin as a control pin causes that pin to be an
input. Register 0x102 to Register 0x108 control both the nature
of the pin (either status or control via Bit D7), as well as the
selection of the status source or control destination associated
with the pin via Bits[D6:D0]. During power-up or reset, the
Mx pins temporarily become inputs and only allow the device to
autoconfigure. Figure 46 is a block diagram of the Mx pin
functionality.
The Mx pin control logic uses special register write detection
logic to prevent these pins from behaving unpredictably when the
Mx pin function changes, especially when changing mode from
input to output or vice versa.
When an Mx pin functions as an output, it continues operating
according to the prior function, even after the user programs
the corresponding registers. However, assertion of an input/output
update causes the corresponding pins to switch to the new
function according to the newly programmed register contents.
Note that changing from one output function to another output
function on an Mx pin does not require special timing to avoid
input/output contention on the pin.
When an Mx pin functions as an input, programming a particular
Mx pin function register causes all the Mx pin control functions
to latch their values. Assertion of an input/output update
switches to the newly programmed pin function, at which time
normal behavior resumes. Note that, when switching from one
input function to another input function on the same pin, the
logic state driven at the input to the pin can change freely
during the interval between writing the new function to the
corresponding register and asserting the input/output update.
When switching the operation of an Mx pin from an input to an
output function, the recommendation is that the external drive
source become high impedance during the interval between
writing the new function and asserting the input/output update.
When switching the operation of an Mx pin from an output to
an input, the recommendation is as follows. First, program the
Mx pin input function to no operation (NOOP) and assert the
input/output update. This configuration avoids input/output
contention on the Mx pin or other undesired behavior because,
prior to the assertion of the input/output update, the device
continues to drive the Mx pin. Following the assertion of the
input/output update, the device releases the Mx pin but ignores
the logic level on the pin due to the programmed NOOP function.
Note that the recommendation is to avoid using a high impedance
source on an Mx pin configured as an input because this may
cause excessive internal current consumption. Second, drive the
Mx pin with Logic 0 or Logic 1 via the desired external source
and program the associated Mx pin register from NOOP to the
desired function.
MULTIFUNCTION PINS AT RESET/POWER-UP
At power-up or in response to a reset operation, the Mx pins
enter a special operating mode. For a brief interval following a
power-up or reset operation, the Mx pins function only as
inputs (the internal drivers enter a high impedance state during
a power-up/reset operation). During this brief interval, the
device latches the logic levels at the Mx inputs and uses this
information to autoconfigure the device accordingly. The Mx
pins remain high-Z until either an EEPROM operation occurs,
in which case M1 or M2 become an I2C master, or the user (or
EEPROM) programs them to be outputs.
AD9542 Data Sheet
Rev. 0 | Page 38 of 61
If the user does not connect external pull-up/pull-down resistors
to the Mx pins, the M3 and M4 pins have internal pull-down
resistors to ensure a predictable start-up configuration. In the
absence of external resistors, the internal pull-down resistors
ensure that the device starts up with the serial port in SPI mode
and without automatically loading data from an external EEPROM
(see Table 26). Although the M0, M1, M2, M5, and M6 pins are
high impedance at startup, connect external 100 kΩ pull-down
or pull-up resistors to these pins to ensure robust operation.
The Mx pin start-up conditions are shown in Table 26. M0, M1,
and M2 are excluded from Table 26 because these pins have no
explicit function during a power-up or reset operation.
Table 26. Mx Pin Function at Startup or Reset
Mx
Pin
Startup/Reset
Function Logic 1 Logic 0
M3 EEPROM load
function
Load from
EEPROM
Do not load from
EEPROM (default)
M4 Serial port
function
I²C mode SPI mode
(default)
M5
I2C address offset
See Table 27
See Table 27
M6 I
2
C address offset See Table 27 See Table 27
When the start-up conditions select the serial port to be I2C
mode (that is, M4 is Logic 1 at startup), the M5 and M6 pins
determine the I2C port device address offset per Table 27. Note
that the logic levels in Table 27 only apply during a power-up or
reset operation.
Table 27. I²C Device Address Offset
M6 M5 M4 Address Offset
X1
X1
0
Not applicable
0 0 1 1001000 (0x48)
0 1 1 1001001 (0x49)
1 0 1 1001010 (0x4A)
1 1 1 1001011 (0x4B)
1 X means don’t care.
STATUS FUNCTIONALITY
Configuring an Mx pin as a status pin gives the user access to
specific internal device status/IRQ functions in the form of a
hardware pin that produces a logic signal. Each Mx pin has a
corresponding Mx function register. To assign an Mx pin as a
status pin, write a Logic 1 to the Mx output enable bit in the
corresponding Mx pin function register.
To assign a specific status/IRQ function to an Mx pin configured
as a status pin, program the appropriate 7-bit code (see Table 30)
to Bits[D6:D0] of the corresponding Mx function register.
See the Interrupt Request (IRQ) section for details regarding
IRQ functionality.
When configured as a status pin, the output mode of an Mx pin
depends on a 2-bit mode code per Table 28. The 2-bit codes reside
in Register 0x100 through Register 0x101, where the 2-bit codes
constitute the Mx receiver/driver bit fields. Note that the Mx
receiver/driver bit fields perform a different function when the
Mx pin is a control pin (see the Control Functionality section).
Table 28. Mx Receiver/Driver Bit Field Codes for Mx Status Pins
Code Mode Description
00 CMOS,
active high
Output is Logic 0 when deasserted and
Logic 1 when asserted (default operating
mode).
01 CMOS,
active low
Output is Logic 1 when deasserted and
Logic 0 when asserted.
10 PMOS,
open drain
Output is high impedance when deasserted
and active high when asserted.
11 NMOS,
open drain
Output is high impedance when deasserted
and active low when asserted.
The PMOS open-drain mode requires an external pull-down
resistor. The NMOS open-drain mode requires an external pull-up
resistor. Note that the open-drain modes enable the implementa-
tion of wire-OR’e d functionality of multiple Mx status pins
(including Mx status pins across multiple AD9542 devices or other
compatible devices—for example, to implement an IRQ bus).
The drive strength of an Mx status pin is programmable via the
corresponding Mx configuration bits (Bits[D6:D0] of the pin
drive strength register). Logic 0 (default) selects normal drive
strength (~6 mA) and Logic 1 selects weak drive strength (~3 mA).
CONTROL FUNCTIONALITY
Configuring an Mx pin as a control pin gives the user control of
the specific internal device functions via an external hardware
logic signal. Each Mx pin has a corresponding Mx function register.
To assign an Mx pin as a control pin, write a Logic 0 to the
Mx output enable bit in the corresponding Mx function register.
To assign an Mx control pin to a specific function, program the
appropriate 7-bit code (see Table 30) to Bits[D6:D0] of the
corresponding Mx function register. See the Interrupt Request
(IRQ) section for details regarding IRQ functionality.
When configured as an Mx control pin, the logical level applied
to the Mx pin translates to the selected device function. It is also
possible to assign multiple Mx control pins to the same control
function with the multiple pins implementing a Boolean expres-
sion. The Boolean operation associated with an Mx control pin
depends on a 2-bit code per Table 29. The 2-bit codes reside in
Register 0x100 through Register 0x101, where the 2-bit codes
constitute the Mx receiver/driver bit fields. Note that the Mx
receiver/driver bit fields perform a different function when the
Mx pin is a status pin (see the Status Functionality section).
Data Sheet AD9542
Rev. 0 | Page 39 of 61
Table 29. Mx Receiver/Driver Bit Field Codes for Mx Control
Pins
Code Boolean Description
00 AND Logical AND the associated Mx control pin
with the other Mx control pins assigned to
the same control function.
01 NOT AND Invert the logical state of the associated Mx
control pin and AND it with the other Mx
control pins assigned to the same control
function.
10 OR Logical OR the associated Mx control pin with
the other Mx control pins assigned to the
same control function.
11 NOT OR Invert the logical state of the associated Mx
control pin and OR it with the other Mx control
pins assigned to the same control function.
The Boolean functionality of aggregated Mx control pins
follows a hierarchy whereby logical OR operations occur before
logical AND operations. The OR and NOT OR operations are
collectively grouped into a single result. A logical AND is then
performed using that result and the remaining AND and NOT
AND operations.
Consider a case where M0, M2, M3, and M6 are all assigned to
the input/output update control function; that is, Bits[D6:D0] in
Register 0x102 through Register 0x108 = 0x01 (see Table 30). In
addition, M0 is assigned for AND operation, M2 for NOT OR
operation, M3 for NOT AND operation, and M6 for OR operation
(that is, the 2-bit codes in Register 0x100 and Register 0x101
according to Table 29). With these settings, the input/output
update function behaves according the following Boolean equation:
Input/output update = (!M2 || M6) && M0 && !M3
where:
! is logical NOT. Therefore, an input/output update occurs when
M0 is Logic 1 and M3 is Logic 0, and either M2 is Logic 0 or M6
is Logic 1.
&& is logical AND.
|| is logical OR.
When an Mx control pin acts on a control function individually
(rather than as part of a group, per the previous example), the
Boolean functionality of the codes in Table 29 reduces to two
possibilities. Namely, Code 00 and Code 10 specify a Boolean
true (the Mx pin logic state applies to the corresponding control
function directly), whereas Code 01 and Code 11 specify a
Boolean false (the Mx pin logic state applies to the corresponding
control function with a logical inversion).
Regarding the source and destination proxy columns in Table 30,
the &&, || and ! symbols denote the Boolean AND, OR, and
NOT operations, respectively.
Table 30. Mx Pin Status and Control Codes
Bits[D6:D0]
(Hex) Control Function Destination Proxy Status Function Source Proxy (or Description)
0x00
No operation (NOOP)
Not applicable
Logic 0, static
Not applicable
0x01 IO_UPDATE Register 0x000F, Bit D0 Logic 1, static Not applicable
0x02 Device power down Register 0x2000, Bit D0 Digital core clock Not applicable
0x03 Clear watchdog timer Register 0x2005, Bit D7 Watchdog timer timeout Not applicable
0x04 Sync all Register 0x2000, Bit D3 SYSCLK calibration in
progress
Register 0x3001, Bit D2
0x05 Unassigned Not applicable SYSCLK lock detect Register 0x3001, Bit D0
0x06 Unassigned Not applicable SYSCLK stable Register 0x3001, Bit D1
0x07 Unassigned Not applicable Channel 0 and Channel 1
PLLs locked
Register 0x3001, Bit D4 && Bit D5
0x08 Unassigned Not applicable PLL0 locked Register 0x3001, Bit D4
0x09 Unassigned Not applicable PLL1 locked Register 0x3001, Bit D5
0x0A Unassigned Not applicable EEPROM save in progress Register 0x3000, Bit D0
0x0B Unassigned Not applicable EEPROM load in progress Register 0x3000, Bit D1
0x0C Unassigned Not applicable EEPROM fault detected Register 0x3000, Bit D2 || Bit D3
0x0D Unassigned Not applicable Temperature sensor limit
alarm
Register 0x3002, Bit D0
0x0E Unassigned Not applicable Unassigned Not applicable
0x0F Unassigned Not applicable Unassigned Not applicable
0x10 Clear all IRQ events Register 0x2005, Bit D0 Any IRQ event The logical OR of all triggered IRQ events
0x11 Clear common IRQ
events
Register 0x2005, Bit D1 Common IRQ event The logical OR of all triggered common
IRQ events
0x12 Clear PLL0 IRQ events Register 0x2005, Bit D2 PLL0 IRQ event The logical OR of all triggered PLL0 IRQ
events
0x13 Clear PLL1 IRQ events Register 0x2005, Bit D3 PLL1 IRQ event The logical OR of all triggered PLL1 IRQ
events
0x14 Unassigned Not applicable REFA demodulator clock Not applicable
AD9542 Data Sheet
Rev. 0 | Page 40 of 61
Bits[D6:D0]
(Hex) Control Function Destination Proxy Status Function Source Proxy (or Description)
0x15 Unassigned Not applicable Unassigned Not applicable
0x16 Unassigned Not applicable REFAA demodulator clock Not applicable
0x17 Unassigned Not applicable Unassigned Not applicable
0x18 Unassigned Not applicable REFB demodulator clock Not applicable
0x19 Unassigned Not applicable Unassigned Not applicable
0x1A Unassigned Not applicable REFBB demodulator clock Not applicable
0x1B Unassigned Not applicable Unassigned Not applicable
0x1C Unassigned Not applicable REFA reference (R) divider
resync
Register 0x300D, Bit D3
0x1D Unassigned Not applicable REFAA R divider resync Register 0x300D, Bit D7
0x1E Unassigned Not applicable REFB R divider resync Register 0x300E, Bit D3
0x1F Unassigned Not applicable REFBB R divider resync Register 0x300E, Bit D7
0x20 Fault REFA Register 0x2003, Bit D0 REFA faulted Register 0x3005, Bit D3
0x21 Fault REFAA Register 0x2003, Bit D1 REFAA faulted Register 0x3006, Bit D3
0x22 Fault REFB Register 0x2003, Bit D2 REFB faulted Register 0x3007, Bit D3
0x23 Fault REFBB Register 0x2003, Bit D3 REFBB faulted Register 0x3008, Bit D3
0x24 Unassigned Not applicable REFA valid Register 0x3005, Bit D4
0x25 Unassigned Not applicable REFAA valid Register 0x3006, Bit D4
0x26 Unassigned Not applicable REFB valid Register 0x3007, Bit D4
0x27
Unassigned
Not applicable
REFBB valid
Register 0x3008, Bit D4
0x28 Timeout REFA
validation
Register 0x2002, Bit D0
(validate REFA if faulted;
otherwise, no action)
REFA active This function represents a logical
combination of several registers and bits
0x29 Timeout REFAA
validation
Register 0x2002, Bit D1
(validate REFAA if
faulted; otherwise, no
action)
REFAA active This function represents a logical
combination of several registers and bits
0x2A Timeout REFB
validation
Register 0x2002, Bit D2
(validate REFB if faulted;
otherwise, no action)
REFB active This function represents a logical
combination of several registers and bits
0x2B Timeout REFBB
validation
Register 0x2002, Bit D3
(validate REFBB if
faulted; otherwise, no
action)
REFBB active This function represents a logical
combination of several registers and bits
0x2C Unassigned Not applicable Not applicable Not applicable
0x2D Unassigned Not applicable Not applicable Not applicable
0x2E
Unassigned
Not applicable
Feedback 0 active
Not applicable
0x2F Unassigned Not applicable Feedback 1 active Not applicable
0x30 Not applicable Not applicable DPLL0 phase locked Register 0x3100, Bit D1
0x31 Not applicable Not applicable DPLL0 frequency locked Register 0x3100, Bit D2
0x32 Not applicable Not applicable APLL0 locked Register 0x3100, Bit D3
0x33 Unassigned Not applicable APLL0 calibration in
progress
Register 0x3100, Bit D4
0x34 Unassigned Not applicable DPLL0 active Register 0x3009, Bit D5 || Bit D4 || Bit D3 ||
Bit D2 || Bit D1 || Bit D0
0x35 Unassigned Not applicable DPLL0 freerun Register 0x3101, Bit D0
0x36 Unassigned Not applicable DPLL0 holdover Register 0x3101, Bit D1
0x37 Unassigned Not applicable DPLL0 switching Register 0x3101, Bit D2
0x38 Unassigned Not applicable DPLL0 tuning word history
status
Register 0x3102, Bit D0
0x39 Unassigned Not applicable DPLL0 tuning word
history updated
Register 0x 3010, Bit D2
0x3A Unassigned Not applicable DPLL0 frequency
clamped
Register 0x3102, Bit D1
0x3B Unassigned Not applicable DPLL0 phase slew limited Register 0x3102, Bit D2
Data Sheet AD9542
Rev. 0 | Page 41 of 61
Bits[D6:D0]
(Hex) Control Function Destination Proxy Status Function Source Proxy (or Description)
0x3C Unassigned Not applicable PLL0 distribution
synchronized
Register 0x3013, Bit D4
0x3D Unassigned Not applicable Unassigned Not applicable
0x3E Unassigned Not applicable DPLL0 phase step
detected
Register 0x3010, Bit D0
0x3F Unassigned Not applicable DPLL0 fast acquisition
active
Register 0x3102, Bit D4
0x40 PLL0 power-down Register 0x2100, Bit D0 DPLL0 fast acquisition
complete
Register 0x3102, Bit D5
0x41 DPLL0 user freerun Register 0x2105, Bit D0 DPLL0 feedback divider
resync
Register 0x3012, Bit D4
0x42 DPLL0 user holdover Register 0x2105, Bit D1 PLL0 distribution phase
slew enable
Indicates when any one of the PLL0
distribution phase slew limiters is actively
limiting
0x43 DPLL0 clear tuning
word history
Register 0x2107, Bit D1 PLL0 distribution
configuration error
Indicates when any one of the PLL0
distribution channel dividers
encountered a phase offset error
0x44 Synchronize PLL0
distribution dividers
Register 0x2101, Bit D3 Unassigned Not applicable
0x45
DPLL0 translation
profile select, Bit 0
Register 0x2105, Bit D4
Unassigned
Not applicable
0x46 DPLL0 translation
profile select, Bit 1
Register 0x2105, Bit D5 Unassigned Not applicable
0x47 DPLL0 translation
profile select, Bit 2
Register 0x2105, Bit D6 Unassigned Not applicable
0x48 Unassigned Not applicable Unassigned Not applicable
0x49 Unassigned Not applicable Unassigned Not applicable
0x4A Unassigned Not applicable Unassigned Not applicable
0x4B Unassigned Not applicable Unassigned Not applicable
0x4C Unassigned Not applicable Unassigned Not applicable
0x4D Unassigned Not applicable Unassigned Not applicable
0x4E Unassigned Not applicable Unassigned Not applicable
0x4F Unassigned Not applicable Unassigned Not applicable
0x50 Mute OUT0A Register 0x2102, Bit D2 DPLL1 phase locked Register 0x3200, Bit D1
0x51 Mute OUT0AA Register 0x2102, Bit D3 DPLL1 frequency locked Register 0x3200, Bit D2
0x52 Reset OUT0A/
OUT0AA driver
Register 0x2102, Bit D5 APLL1 locked Register 0x3200, Bit D3
0x53 Mute OUT0B Register 0x2103, Bit D2 APLL1 calibration in
progress
Register 0x3200, Bit D4
0x54 Mute OUT0BB Register 0x2103, Bit D3 DPLL1 active Register 0x300A, Bit D5 || Bit D4 || Bit D3 ||
Bit D2 || Bit D1 || Bit D0
0x55 Reset OUT0B/
OUT0BB driver
Register 0x2103, Bit D5 DPLL1 freerun Register 0x3201, Bit D0
0x56 Mute OUT0C Register 0x2104, Bit D2 DPLL1 holdover Register 0x3201, Bit D1
0x57 Mute OUT0CC Register 0x2104, Bit D3 DPLL1 switching Register 0x3201, Bit D2
0x58 Reset OUT0C/
OUT0CC driver
Register 0x2104, Bit D5 DPLL1 tuning word
history status
Register 0x3202, Bit D0
0x59
Mute OUT0xP/
OUT0xN
Register 0x2101, Bit D1
DPLL1 tuning word
history updated
Register 0x3015, Bit D2
0x5A Reset OUT0xP/
OUT0xN drivers
Register 0x2101, Bit D2 DPLL1 frequency
clamped
Register 0x3202, Bit D1
0x5B Channel 0 N-shot
request
Register 0x2101, Bit D0 DPLL1 phase slew limited Register 0x3202, Bit D2
0x5C Unassigned Not applicable PLL1 distribution
synchronized
Register 0x3018, Bit D4
0x5D Unassigned Not applicable Unassigned Not applicable
AD9542 Data Sheet
Rev. 0 | Page 42 of 61
Bits[D6:D0]
(Hex) Control Function Destination Proxy Status Function Source Proxy (or Description)
0x5E Unassigned Not applicable DPLL1 phase step
detected
Register 0x3015, Bit D0
0x5F Unassigned Not applicable DPLL1 fast acquisition
active
Register 0x3202, Bit D4
0x60 PLL1 power-down Register 0x2200, Bit D0 DPLL1 fast acquisition
complete
Register 0x3202, Bit D5
0x61 DPLL1 force freerun Register 0x2205, Bit D0 DPLL1 feedback divider
resync
Register 0x3017, Bit D4
0x62 DPLL1 force holdover Register 0x2205, Bit D1 PLL1 distribution phase
slew enable OR’ed
Indicates when any one of the PLL1
distribution phase slew limiters is actively
limiting
0x63 DPLL1 clear tuning
word history
Register 0x2207, Bit D1 PLL1 distribution phase
control error OR’ed
Indicates when any one of the PLL1
distribution channel dividers
encountered a phase offset error
0x64
Synchronize PLL1
distribution dividers
Register 0x2201, Bit D3
Unassigned
Not applicable
0x65 DPLL1 translation
profile select, Bit 0
Register 0x2205, Bit D4 Unassigned Not applicable
0x66 DPLL1 translation
profile select, Bit 1
Register 0x2205, Bit D5 Unassigned Not applicable
0x67 DPLL1 translation
profile select, Bit 2
Register 0x2205, Bit D6 Unassigned Not applicable
0x68 Unassigned Not applicable Unassigned Not applicable
0x69 Unassigned Not applicable Unassigned Not applicable
0x6A Unassigned Not applicable Unassigned Not applicable
0x6B
Unassigned
Not applicable
Unassigned
Not applicable
0x6C Unassigned Not applicable Unassigned Not applicable
0x6D Unassigned Not applicable Unassigned Not applicable
0x6E Unassigned Not applicable Unassigned Not applicable
0x6F Unassigned Not applicable Unassigned Not applicable
0x70 Mute OUT1A Register 0x2202, Bit D2 Not applicable Not applicable
0x71 Mute OUT1AA Register 0x2202, Bit D3 Not applicable Not applicable
0x72 Reset OUT1A/OUT1AA
driver
Register 0x2202, Bit D5 Not applicable
0x73 Mute OUT1B Register 0x2203, Bit D2 Not applicable
0x74 Mute OUT1BB Register 0x2203, Bit D3 Not applicable
0x75
Reset OUT1B/OUT1BB
driver
Register 0x2203, Bit D5
Not applicable
0x76 Mute OUT1xP/OUT1xN
drivers
Register 0x2201, Bit D1 Unassigned Not applicable
0x77 Reset OUT1xP/OUT1xN
drivers
Register 0x2201, Bit D2 Unassigned Not applicable
0x78 Channel 1 N-shot
request
Register 0x2201, Bit D0 Timestamp 0 event
detected
Register 0x300E, Bit D2
0x79 Unassigned Not applicable Timestamp 1 event
detected
Register 0x300E, Bit D3
0x7A Unassigned Not applicable Skew measurement
detected
Register 0x300E, Bit D4
0x7B Unassigned Not applicable Unassigned Not applicable
0x7C Unassigned Not applicable Unassigned Not applicable
0x7D Unassigned Not applicable Unassigned Not applicable
0x7E Unassigned Not applicable Unassigned Not applicable
0x7F Unassigned Not applicable Unassigned Not applicable
Data Sheet AD9542
Rev. 0 | Page 43 of 61
INTERRUPT REQUEST (IRQ)
The AD9542 monitors certain internal device events potentially
allowing them to trigger an IRQ event. Three groups of registers
(see Figure 47) control the IRQ functionality within the AD9542:
• IRQ monitor registers (Register 0x300B through
Register 0x3019)
• IRQ mask registers (Register 0x10C through Register 0x11A)
• IRQ clear registers (Register 0x2006 through Register 0x2014)
The IRQ logic can indicate an IRQ event status result for any
specific device event(s) via the logical OR of the status of all the
IRQ monitor bits. In addition, the IRQ logic offers IRQ event
status results for particular groups of specific IRQ events,
namely, the PLL0 IRQs, PLL1 IRQs, and common IRQs (see
Figure 47).
The PLL0 IRQ group includes all device events associated with
DPLL0 and APLL0. The PLL1 IRQ group includes all device
events associated with DPLL1 and APLL1. The common IRQ
group includes events associated with the system clock, the
watchdog timer, and the EEPROM.
IRQ MONITOR
The IRQ monitor registers (in the general status section of the
register map) maintain a record of specific IRQ events. The
occurrence of a specific device event results in the setting and
latching of the corresponding bit in the IRQ monitor. The
output of the IRQ monitor provides the mechanism for
generating IRQ event status results (see the PLL0 IRQ, PLL1
IRQ, common IRQ, or any IRQ signal shown in Figure 47).
IRQ MASK
The IRQ mask registers (in the Mx pin status and control section
of the register map) comprise a bit for bit correspondence with
the specific IRQ event bits within the IRQ monitor. Writing a
Logic 1 to a mask bit enables (unmasks) the corresponding
specific device event to the IRQ monitor. A Logic 0 (default)
disables (masks) the corresponding specific device event to the
IRQ monitor. Therefore, a specific IRQ event is the result of a
logical AND of a specific device event and its associated IRQ,
mask bit.
The presence of the IRQ mask allows the user to select certain
device events for generating an IRQ event, while ignoring
(masking) all other specific device events from contributing to
an IRQ event status result (PLL0 IRQ, PLL1 IRQ, common IRQ
or any IRQ signal in Figure 47). Note that the default state of the
IRQ mask register bits is Logic 0; therefore, the device is not
capable of generating an IRQ event status result until the user
populates the IRQ mask with a Logic 1 to unmask the desired
specific IRQ events. Writing a Logic 1 to an IRQ mask bit may
result in immediate indication of an IRQ status event result if the
corresponding specific device event is already asserted (that is,
the device previously registered the corresponding device event).
IRQ CLEAR
The IRQ clear registers (in the operational controls section of
the register map) comprise a bit for bit correspondence with
the IRQ monitor. Writing a Logic 1 to an IRQ clear bit forces
the corresponding IRQ monitor bit to Logic 0, thereby clearing
that specific IRQ event. Note that the IRQ clear registers are
autoclearing; therefore, after writing a Logic 1 to an IRQ clear bit,
the device automatically restores the IRQ clear bit to Logic 0.
The IRQ event status results remain asserted until the user
clears all of the bits in the IRQ monitor responsible for the IRQ
status result (that is, the entire group of status bits associated
with PLL0 IRQ, PLL1 IRQ, common IRQ, or any IRQ signal
shown in Figure 47).
Although it is not recommended, in certain applications, it
may be desirable to clear an entire IRQ group all at one time.
Register 0x2005 provides four bits for clearing IRQ groups.
Bit D0 clears all IRQ monitor bits. Bit D1 clears the common
IRQ bits. Bit D2 clears the PLL0 IRQ bits. Bit D3 clears the
PLL1 IRQ bits.
Alternately, the user can program any of the multifunction pins
as an input for clearing an IRQ group, which allows clearing an
IRQ group with an external logic signal rather than by writing
to Register 0x2005 (see Figure 47).
The recommendation for clearing IRQ status events is to first
service the specific IRQ event (as needed) and then clear the
specific IRQ for that particular IRQ event. Clearing IRQ groups
via Register 0x2005 or via an Mx pin requires great care.
Clearing an IRQ group all at one time may result in the
unintentional clearing of one or more asserted IRQ monitor
bits. Clearing asserted IRQ monitor bits eliminates the record of
the associated device events, subsequently erasing any history of
those events having occurred.
AD9542 Data Sheet
Rev. 0 | Page 44 of 61
IRQ MASK BITS
REGISTER 0x010C TO
REGISTER 0x011A
1 = ENABLE
0 = MASK (DEFAULT)
IRQ MONITOR BITS
REGISTER 0x300B TO
REGISTER 0x3019
DEVICE EVENT SOURCES
SPECIFIC IRQ EVENT STATUS
GROUPED DEVICE EVENTS
IRQ CLEAR BITS
REGISTER 0x2006 TO
REGISTER 0x2014
ANY
IRQ
Mx PIN FUNCTION LOGIC
Mx PINS
CLEAR COMMON IRQS
IRQ CLEAR
GROUP/ALL
BITS
REGISTER 0x2005
SPECIFIC DEVICE EVENTS
GROUPED
IRQ EVENT
STATUS
GROUPED
IRQ CLEAR
COMMON IRQ
PLL1 IRQ
PLL0 IRQ
CLEAR PLL1 IRQS
CLEAR PLL0 IRQS
CLEAR ALL IRQS
15826-005
Figure 47. IRQ System Diagram
Data Sheet AD9542
Rev. 0 | Page 45 of 61
WATCHDOG TIMER
The watchdog timer is a general-purpose programmable timer
capable of triggering a specific IRQ event (see Figure 48). The
timer relies on the system clock, however; therefore, the system
clock must be present and locked for the watchdog timer to be
functional. The bit fields associated with the watchdog timer
reside in the Mx pin status and control function section of the
register map.
The user sets the period of the watchdog timer by programming
the watchdog timer (ms) bit field with a 16-bit timeout value. A
nonzero value sets the timeout period in units of milliseconds,
providing a range of 1 ms to 65.535 sec, whereas a zero value
(0x0000, the default value) disables the timer. The relative accuracy
of the timer is approximately 0.1% with an uncertainty of
0.5 ms. Note that whenever the user writes a 16-bit timeout
value to the watchdog timer, it automatically clears the timer,
ensuring a correct timeout period (per the new value) starting
from the moment of the bit field update.
The watchdog timer (ms) bit field relates to the timeout period
as follows:
Watchdog Timer (ms) = Timeout Period × 103
To determine the value of the watchdog timer (ms) bit field
necessary for a timeout period of 10 sec,
Watchdog Timer (ms) = Timeout Period × 103
= 10 × 103
= 10,000
= 0x2710 (hexadecimal)
If enabled, the timer runs continuously and generates a timeout
IRQ event when the timeout period expires. The user has access
to the watchdog timer status via its associated IRQ monitor bit
or by assigning it directly to an Mx status pin. In the case of an
Mx status pin, the timeout event of the watchdog timer is a
pulse spanning 96 system clock periods (approximately 40 ns).
There are two ways to reset the watchdog timer, thereby preventing
it from indicating a timeout event. The first method is by
writing a Logic 1 to the clear watchdog bit (an autoclearing bit)
in the operational controls section of the register map.
Alternatively, the user can program any of the multifunction
pins as a control pin to reset the watchdog timer, which allows
the user to reset the timer by means of a hardware pin rather
than using the serial port.
There are two typical cases for employing the watchdog timer.
Both cases assume that the watchdog timer output appears at
the output of an appropriately configured Mx status pin (the
watchdog timer output for the following case descriptions). The
first case is for an external device (for example, an FPGA or
microcontroller) to monitor the watchdog timer output using it
as a signal to carry out periodic housekeeping functions. The
second case is to have the watchdog timer output connected to
the external device, such that the assertion of the watchdog
output resets the external device. In this way, under normal
operation, the external device repeatedly resets the watchdog
timer by either writing Logic 1 to the clear watchdog bit or by
asserting an Mx control pin configured for clearing the watchdog.
In this way, as long as the external device keeps resetting the
watchdog timer before it times out, the watchdog timer does
not generate an output signal. As such, the watchdog timer does
not reset the external device. However, if the external device
fails to reset the watchdog timer before its timeout period
expires, the watchdog timer eventually times out, resetting the
external device via the appropriately configured Mx status pin.
TIMER
CLK OUT
1kHz
PRESET
16
REGISTER 0x2005,
BIT D7
CLEAR
Mx PIN FUNCTION LOGIC
Mx PI NS
40ns
TO IRQ EVENT
SOURCE LOGIC
REGISTER 0x010A TO RE GI S TER 0x010B
CLEAR
WATCHDOG
VIA Mx PIN
WATCHDOG
OUTPUT VIA
Mx PIN
CLEAR
WATCHDOG
WATCHDOG
TIMER
(
MS
)
TEXT = BIT(S) IN THE REGIST ER MAP
15826-105
Figure 48. Watchdog Timer
AD9542 Data Sheet
Rev. 0 | Page 46 of 61
LOCK DETECTORS
DPLL LOCK DETECTORS
DPLL Phase Lock Detector
Each DPLL channel (DPLL0 and DPLL1) contains an all digital
phase lock detector. The user controls the threshold sensitivity
and hysteresis of the phase detector via the source profiles.
The phase lock detector provides the user with two status bits in
the status readback PLLx section the register map. The DPLLx
phase lock bit latches to Logic 1 when the DPLL changes state
from not phase locked to phase locked. The DPLLx phase unlock
bit latches to Logic 1 when the DPLL changes state from phase
locked to not phase locked. The DPLLx phase lock bits are
located in Register 0x3100 and 0x3200, respectively. Because
these bits can change dynamically, it is strongly recommended
that the user set an IRQ for these bits. When using the IRQ
function, it is possible for the IRQ status to indicate Logic 1 for
an IRQ function that was just enabled if that condition is true at
the time the IRQ is enabled. Therefore, the user must clear
them via the IRQ map clear DPLL0 (Register 0x200B to
Register 0x200F), IRQ map clear DPLL1 (Register 0x2010 to
Register 0x2014), sections of the register map to obtain visibility of
subsequent state transitions of the phase lock detector.
The phase lock detector behaves in a manner analogous to
water in a tub (see Figure 49). The total capacity of the tub
is 4096 units, with −2048 denoting empty, 0 denoting the 50%
point, and +2047 denoting full. The tub also has a safeguard to
prevent overflow. Furthermore, the tub has a low water mark
at −1025 and a high water mark at +1024. To change the water
level, the phase lock detector adds water with a fill bucket or
removes water with a drain bucket. To specify the size of the fill
and drain buckets, use the unsigned 8-bit Profile x phase lock fill
rate and Profile x phase lock fill rate bit field (where x is a value
from 0 through 7, corresponding to a particular source profile).
The water level in the tub is what the lock detector uses to
determine the lock and unlock conditions. When the water level
is below the low water mark (−1025), the lock detector indicates
an unlock condition. Conversely, when the water level is above
the high water mark (+1024), the lock detector indicates a lock
condition. When the water level is between the marks, the lock
detector holds its last condition. Figure 49 shows this concept
with an overlay of an example of the instantaneous water level
(vertical) vs. time (horizontal) and the resulting lock/unlock
states.
0
2047
–2048
1024
–1025
LOCK LEVEL
UNLOCK L E VE L
LOCKED UNLOCKED
PREVIOUS
STATE
FILL
RATE DRAIN
RATE
15826-345
Figure 49. Lock Detector Diagram
During any given PFD phase error sample, the lock detector
either adds water with the fill bucket or removes water with the
drain bucket (one or the other, but not both). The decision of
whether to add or remove water depends on the threshold level
specified by the user in the 24-bit unsigned Profile x phase lock
threshold bit field. The bit field value is the desired threshold in
picoseconds. Thus, the phase lock threshold extends from 0 ps
to 16.7 µs and represents the phase error at the output of the
PFD. Though the programming range supports 0 ps as a lower
limit, in practice, the minimum value must be greater than 50 ps.
The phase lock detector compares the absolute value of each
phase error sample at the output of the PFD to the programmed
phase threshold value. If the absolute value of the phase error
sample is less than or equal to the programmed phase threshold
value, the detector control logic adds one fill bucket into the
tub. Otherwise, it removes one drain bucket from the tub. Note
that it is the magnitude, relative to the phase threshold value,
that determines whether to fill or drain the bucket, and not the
polarity of the phase error sample.
An exception to the fill/drain process occurs when the phase
slew limiter is active. When the phase slew limiter is actively in
the limiting process, the lock detector blocks fill events, allowing
only drain events to occur.
When more filling is taking place than draining, the water level
in the tub eventually rises above the high water mark (+1024),
which causes the lock detector to indicate lock. When more
draining is taking place than filling, the water level in the tub
eventually falls below the low water mark (−1024), which causes
the lock detector to indicate unlock. The ability to specify the
threshold level, fill rate, and drain rate enables the user to tailor
the operation of the lock detector to the statistics of the timing
jitter associated with the input reference signal. Note that, for
debug purposes, the user can make the fill or drain rate zero to
force the lock detector to indicate a lock or unlock state,
respectively.
Note that whenever the AD9542 enters freerun or holdover
mode, the DPLL phase lock detector indicates an unlocked state.
For more information on how to choose the appropriate phase
lock threshold, fill rate, and drain rate values for a given
application, refer to the AN-1061 Application Note.
DPLL Frequency Lock Detector
The operation of the frequency lock detector is identical to that
of the phase lock detector, with two exceptions:
• The fill or drain decision is based on the period deviation
between the reference of the DPLL and the feedback
signals, instead of the phase error at the output of the PFD.
• The frequency lock detector is unaffected by the state of
the phase slew limiter.
Data Sheet AD9542
Rev. 0 | Page 47 of 61
The frequency lock detector provides the user with two status
bits in the IRQ map DPLLx mask section of the register map. The
DPLLx frequency lock bit (where x is 0 or 1) latches to Logic 1
when the DPLL changes state from not frequency locked to
frequency locked. The DPLLx frequency unlock bit latches to
Logic 1 when the DPLL changes state from frequency locked to
not frequency locked. Because these are latched bits, the user
must clear them via the IRQ map DPLLx clear section of the
register map to obtain visibility of subsequent state transitions
of the frequency lock detector.
The frequency lock detector uses the 24-bit unsigned Profile x
frequency lock threshold bit field (where x is a value from 0
through 7, corresponding to a particular source profile),
specified in units of picoseconds. Thus, the frequency threshold
value extends from 0 ps to 16.7 µs and represents the absolute
value of the difference in period between the reference and
feedback signals at the input to the DPLL.
Profile x Frequency Lock Threshold = |1/fREF − 1/fFB|/10−12
where:
fREF is the frequency of the signal at the DPLL PFD reference
input.
fFB is the frequency of the signal at the DPLL PFD feedback
input.
Consider a case where it is desirable to set the Profile x
frequency lock threshold bit field to meet the frequency
threshold when the signal from the reference TDC is 80 kHz
and the signal from the feedback TDC is 79.32 kHz (or vice
versa).
Profile x Frequency Lock Threshold = |1/fREF − 1/fFB|/10−12
= |1/80,000 − 1/79,320|/10−12
= 170,161 (nearest integer)
= 0x0298B1 (hexadecimal)
For more information on how to choose the appropriate frequency
lock threshold, fill rate, and drain rate values for a given application,
refer to the AN-1061 Application Note.
AD9542 Data Sheet
Rev. 0 | Page 48 of 61
PHASE STEP DETECTOR
PHASE STEP LIMIT
Although the AD9542 has the ability to switch between multiple
reference inputs, some applications use only one input and handle
reference switching externally (see Figure 50). Unfortunately,
this arrangement forfeits the ability of the AD9542 to mitigate
the output disturbance associated with a reference switchover,
because the reference switchover is not under the control of the
AD9542. However, the AD9542 offers a phase transient threshold
detection feature to help identify when an external reference
switchover occurs and to act accordingly.
AD9542
REFx, REFxx
REFE RE NCE 1
REFE RE NCE 2
SWITCHOVER
CONTROL
15826-346
Figure 50. External Reference Switching
Phase transient threshold detection works by monitoring the
output of the DPLL phase detector for phase transients, but in a
manner that is somewhat jitter tolerant. Otherwise, the phase
transient threshold detector is prone to false positives.
To activate the phase transient threshold detection, program the
32-bit unsigned Profile x phase step threshold bit field (where x
is a value from 0 through 7, corresponding to a particular
source profile). The default value is zero, which disables the phase
transient threshold detector. A nonzero value denotes the
desired phase step threshold in units of picoseconds per the
following equation:
Phase Step Threshold = Profile x Phase Step Threshold × 10−12
Note that the phase transient threshold detector is not active
unless the DPLL indicates frequency locked status.
As an example, determine the value of the Profile x phase step
threshold bit field necessary for a 12 ns limit. Solving the
previous equation for the phase step limit yields
Profile x Phase Step Threshold = (12 × 10−9)/10−12
= 12,000
= 0x00002EE0 (hexadecimal)
To reduce the likelihood of jitter induced threshold violations,
choose a phase step threshold of at least two times the expected
rms jitter (σJITTER) associated with the input reference signal.
Profile x Phase Step Threshold ≥ 2 × σJITTER
As such, in the previous example with Profile x phase step
threshold = 12,000, an input signal with 12 ns rms jitter is likely
to produce false positives because the signal violates the
previously described inequality. To reduce the likelihood of a
false positive, the inequality indicates Profile x phase step
threshold = 24,000 is a better choice. In fact, even with a value
of 24,000, there is still a slight probability of a jitter sample
exceeding 2 × σJITTER. As such, scaling σJITTER by four to six is an
even better choice.
When a phase transient occurs that exceeds the prescribed
value, one or both of the following two events occurs,
depending on the state of the enable step detect reference fault
bit in the operational control Channel 0 and Channel 1 (DPLL0
and DPLL1) sections of the register map:
•Logic 0: the DPLL initiates a new acquisition sequence.
•Logic 1: the reference monitor is reset.
When the enable step detect reference fault bit is Logic 0
(default), detection of a phase step causes only the first event to
occur. By initializing a new DPLL acquisition sequence, the
DPLL can take advantage of the fast acquisition feature,
assuming it is active, which is especially helpful for very low loop
bandwidth applications. In addition, a new acquisition manages
the impact of the phase step by either building out the phase or
slewing to the new phase in a hitless manner.
When the enable step detect reference fault bit is Logic 1,
detection of a phase step causes both events to occur. Because
exceeding the phase step threshold in this case implies an
external switch to a new reference, resetting the reference
monitor forces it to establish new reference statics.
The phase transient threshold detector provides the user with a
live status bit in the status readback PLLx section of the register
map, as well as a latched status bit in the IRQ map DPLLx read
section of the register map. The DPLLx phase step detect bit
(where x is 0 or 1) latches to Logic 1 on threshold violation of
the phase transient threshold detector. Because this is a latched
bit, the user must clear it via the IRQ map DPLLx clear section
of the register map to obtain visibility of subsequent threshold
violations detected by the phase step detector.
Mitigating Phase Step Limit False Positives
When enabled, the phase transient threshold detector operates
continuously, as long as the associated reference is the active
reference for the DPLL (DPLL0 or DPLL1, assuming the DPLL
is frequency locked. As such, any phase disturbance at the input
to the phase detector of the DPLL is subject to violating the
threshold of the phase transient threshold detector. This
violation includes a user induced phase adjustment via the
DPLLx phase offset bit field or the Profile x phase skew bit field.
To mitigate false triggering of the phase transient threshold
detector (when enabled) due to intentional phase adjustments,
the user can employ the phase slew rate limiter DPLL.
The following formula relates the maximum phase slew rate
(MPSR) necessary to prevent inadvertent triggering of the
phase transient threshold detector:
MPSR = (P + F)/7
where:
P is the phase transient threshold detector limit (in
picoseconds).
F is the frequency (in Hz) at the input of the DPLL phase
detector.
Data Sheet AD9542
Rev. 0 | Page 49 of 61
Note that this formula ignores other contributors to phase error,
including jitter, frequency offset, and propagation delay variation.
If the user has a prior knowledge of the timing of an external
event, such as the switching of the reference input clock source
via an external mux, rather than using the phase transient step
detector, a more robust solution is to invalidate the associated
reference manually. To do so, force a reference fault condition
via the appropriate operational controls bit field. Using this
method imposes the least impact on the steady state operation of
the device. The only steady state impact is that the validation
timer of the associated reference must be set to a duration that
is longer (with suitable margin) than the duration between the
assertion of the force fault condition and the occurrence of the
external event.
SKEW ADJUSTMENT
Skew adjustment allows the user to associate a fixed phase offset
with a reference input, which, for example, is useful in applications
with redundant GNSS/GPS reference sources. That is, a user
may have two or more GNSS/GPS sources that have identical
frequency but may exhibit a fixed time offset due to a mismatch
between antenna cable lengths.
To activate the skew adjustment feature, program the 24-bit
signed Profile x phase skew bit field (where x is the profile number,
Profile 0 to Profile 7). The default value is zero, which disables
the skew adjustment feature. A nonzero value enables the skew
adjustment feature and denotes the desired time skew in units
of picoseconds per the following equation:
Time Skew = Profile x Phase Skew × 10−12
As an example, determine the value of the Profile x phase skew
bit field necessary for a time skew of −35 ns. Solving the
previous equation for the Profile x phase skew yields
Profile x Phase Skew = (−35 × 10−9)/10−12
= −35,000
= 0xFF7748 (hexadecimal)
AD9542 Data Sheet
Rev. 0 | Page 50 of 61
EEPROM USAGE
OVERVIEW
The AD9542 supports an external, I2C-compatible, EEPROM
with dedicated access. With some restrictions, the AD9542 also
supports multidevice access to a single external EEPROM on a
shared I2C common bus. The AD9542 has an on-chip I2C
master to interface to the EEPROM through the Mx pins.
Because the default register settings of the AD9542 do not
define a particular frequency translation, the user must factory
program the EEPROM content before it can be downloaded to
the register map (either automatically or manually). If desired,
the user can store custom device configurations by manually
forcing an upload to the EEPROM via the register map.
EEPROM CONTROLLER GENERAL OPERATION
EEPROM Controller
The EEPROM controller governs all aspects of communication
with the EEPROM. Because the I2C interface uses a 100 kHz
(normal mode) or 400 kHz (fast mode) communication link,
the controller runs synchronous to an on-chip generated clock
source suitable for use as the I2C serial clock. The on-chip oscillator
enables asynchronously immediately on a request for activation
of the controller. When the oscillator starts, it notifies the
controller of its availability, and the controller activates. After
the requested controller operation is complete, the controller
disables the clock generator and returns to an idle state.
EEPROM Download
An EEPROM download transfers contents from the EEPROM
to the AD9542 programming registers and invokes specific
actions per the instructions stored in the EEPROM (see Table 31).
Automatic downloading is the most common method for
initiating an EEPROM download sequence, which initiates at
power-up of the AD9542, provided Pin M3 is Logic 1 at power-
up (see the Multifunction Pins at Reset/Power-Up section).
Alternatively, instead of cycling power to the AD9542 to initiate an
EEPROM download, the user can force the RESETB pin to
Logic 0, force Pin M3 to Logic 1, and then return the RESETB
pin to Logic 1 and remove the drive source from Pin M3.
The user can also request an EEPROM download on demand
(that is, without resetting or cycling power to the AD9542) by
writing a Logic 1 to the EEPROM load bit in the EEPROM
section of the register map.
Note that the load from EEPROM bit does not require an
input/output update. Writing a Logic 1 to this bit immediately
triggers a download sequence.
The EEPROM controller sets the EEPROM load in progress bit
(in the general status section of the register map) to Logic 1
while the download sequence is in progress as an indication to
the user that the controller is busy.
EEPROM Upload
To store the AD9542 register contents in the EEPROM, the user
must write a Logic 1 to the EEPROM save bit in the EEPROM
section of the register map. The EEPROM save bit does not
require an input/output update. Writing a Logic 1 to this bit
immediately triggers an upload sequence.
The AD9542 has the equivalent of a write protect feature in that
the user must write a Logic 1 to the EEPROM write enable bit
(in the EEPROM section of the register map) prior to requesting an
upload to the EEPROM. Attempting to upload to the EEPROM
without first setting the EEPROM write enable bit results in a
fault indication (that is, the AD9542 asserts the EEPROM fault bit
in the general status section of the register map).
A prerequisite to an EEPROM upload is the existence of an upload
sequence stored in the 15-byte EEPROM sequence section of
the register map. That is, the user must store a series of upload
instructions (see the EEPROM Instruction Set section) in the
EEPROM sequence section of the register map prior to executing
an EEPROM upload.
The EEPROM controller performs an upload sequence by reading
the instructions stored in the EEPROM sequence section of the
register map byte by byte and executing them in order. That is,
the data stored in the EEPROM sequence section of the register
map are instructions to the EEPROM controller on what to
store in the EEPROM (including operational commands and
AD9542 register data).
Note that the EEPROM controller sets the EEPROM save in
progress bit (in the status readback section of the register map)
to Logic 1 while the upload sequence is in progress as an indication
to the user that the controller is busy.
Because the EEPROM sequence section of the register map is
only 15 bytes, it typically cannot hold enough instructions to
upload a complete set of AD9542 data to the EEPROM. Therefore,
most upload sequences necessitate that the user upload a series
of subsequences. For example, to accomplish a required upload
sequence consisting of 20 bytes of instructions, perform the
following procedure:
1. Write the first 14 instructions to the EEPROM sequence
registers in the EEPROM section of the register map, with
the 15th instruction being a pause instruction (see Table 31).
2. Initiate an EEPROM upload by writing Logic 1 to the
EEPROM save bit. When the EEPROM controller reaches
the pause instruction, it suspends the upload process and
waits for another assertion of the EEPROM save bit.
3. While the controller pauses, write the remaining six bytes
of the upload sequence into the EEPROM sequence
registers in the EEPROM section of the register map,
followed by an end of data instruction (see Table 31).
4. Initiate an EEPROM upload by writing Logic 1 to the
EEPROM save bit. When the EEPROM controller reaches
the end of data instruction, it terminates the upload process.
Data Sheet AD9542
Rev. 0 | Page 51 of 61
The previous procedure is an example of an upload sequence
consisting of two subsequences. Most upload sequences require
more than two subsequences; however, the procedure is the same.
Specifically, partition a long sequence into several subsequences
by using the pause instruction at the end of each subsequence
and the end of data instruction at the end of the final subsequence.
EEPROM Checksum
When the EEPROM controller encounters an end of data
instruction (see Table 31) during an upload sequence, it
computes a 32-bit cyclic redundancy check (CRC) checksum
and appends it to the stored data in the EEPROM. Similarly,
when the EEPROM controller executes a download sequence, it
computes a checksum on the fly. At the end of a download
sequence, the EEPROM controller compares the newly
computed checksum to the one stored in the EEPROM. If the
two checksums do not match, the EEPROM controller asserts
the EEPROM CRC error bit in the status readback section of
the register map.
To minimize the possibility of downloading a corrupted
EEPROM data set, the user can execute a checksum test by
asserting the verify EEPROM CRC bit in the EEPROM section
of the register map, which causes the EEPROM controller to
execute a download sequence, but without actually transferring
data to the AD9542 registers. The controller still computes an
on the fly checksum, performs the checksum comparison, and
asserts the EEPROM CRC error bit if the checksums do not
match. Therefore, after the device deasserts the EEPROM load
in progress bit, the user can check the EEPROM CRC fault bit
to determine if the test passed (that is, EEPROM CRC error = 0).
However, even if the test fails, device operation is unaffected
because there was no transfer of data to the AD9542 registers.
EEPROM Header
The EEPROM controller adds a header to stored data that
carries information related to the AD9542, such as
• Vendor ID
• Chip type
• Product ID
• Chip revision
At the beginning of an EEPROM download sequence, the
EEPROM controller compares the stored header values to the
values in the corresponding registers of the AD9542. If the
controller detects a mismatch, it asserts the EEPROM fault bit
in the status readback section of the register map and
terminates the download.
EEPROM INSTRUCTION SET
The EEPROM controller relies on a combination of instructions
and data. An instruction consists of a single byte (eight bits).
Some instructions require subsequent bytes of payload data.
That is, some instructions are self contained operations, whereas
others are directions on how to process subsequent payload
data. A summary of the EEPROM controller instructions is
shown in Table 31.
When the controller downloads the EEPROM contents to the
AD9542 registers, it does so in a linear fashion, stepping
through the instructions stored in the EEPROM. However, when
the controller uploads to the EEPROM, the sequence is a nonlinear
combination of various parts of the register map, as well as
computed data that the controller calculates on the fly.
Table 31. EEPROM Controller Instruction Set Summary
Instruction Code
(Hexadecimal) Response Comments
0x00 to 0x7F
Register transfer
Requires a 2-byte register address suffix
0x80 Input/output update Assert input/output update during download
0x81 to 0x8F Not applicable Undefined
0x90 Calibrate APLLs Calibrate the system clock PLL, APLL0, and APLL1 during download
0x91 Calibrate the system clock PLL Calibrate only the system clock PLL during download
0x92 Calibrate APLL0 Calibrate only APLL0 during download
0x93 Calibrate APLL1 Calibrate only APLL1 during download
0x94 to 0x97 Not applicable Reserved/unused
0x98
Force freerun
Force DPLL0 and DPLL1 to freerun during download
0x99 Force DPLL0 freerun Force only DPLL0 to freerun during download
0x9A Force DPLL1 freerun Force only DPLL1 to freerun during download
0x9B to 0x9F Not applicable Reserved/unused
0xA0 Synchronize outputs Synchronize all distribution outputs during download
0xA1 Synchronize Channel 0 Synchronize only Channel 0 distribution outputs during download
0xA2 Synchronize Channel 1 Synchronize only Channel 1 distribution outputs during download
0xA3 to 0xAF Not applicable Reserved/unused
0xB0 Clear condition Apply Condition 0 and reset the condition map
0xB1 to 0xBF Set condition Apply Condition 1 to Condition 15, respectively
0xC0 to 0xFD Not applicable Undefined
0xFE Pause Pause the EEPROM upload sequence
0xFF End of data Marks the end of the instruction sequence
AD9542 Data Sheet
Rev. 0 | Page 52 of 61
Register Transfer Instructions (0x00 to 0x7F)
Instructions with a hexadecimal value from 0x00 through 0x7F
indicate a register transfer operation. Register transfer instructions
require a 2-byte suffix, which constitutes the starting address of
the AD9542 register targeted for transfer (where the first byte
to follow the data instruction is the most significant byte of the
register address). When the EEPROM controller encounters a
data instruction, it knows to interpret the next two bytes as the
register map target address.
Note that the value of the register transfer instruction encodes
the payload length (number of bytes). That is, the EEPROM
controller knows how many register bytes to transfer to/from
the indicated register by adding 1 to the instruction value. For
example, Data Instruction 0x1A has a decimal value of 26;
therefore, the controller knows to transfer 27 bytes to and from
the target register (that is, one more than the value of the
instruction).
Input/Output Update Instruction (0x80)
When the EEPROM controller encounters an input/output
update instruction during an upload sequence, it stores the
instruction in EEPROM. When encountered during a download
sequence, however, the EEPROM controller initiates an
input/output update event (equivalent to the user asserting the
IO_UPDATE bit in the serial port section of the register map).
Device Action Instructions (0x90 to 0xAF)
When the EEPROM controller encounters a device action
instruction during an upload sequence, it stores the instruction
in EEPROM. When encountered during a download sequence,
however, the EEPROM controller executes the specified action
per Table 31.
Conditional Instructions (0xB0 to 0xBF)
The conditional instructions allow conditional execution of
EEPROM instructions during a download sequence. During an
upload sequence, however, they are stored as is and have no
effect on the upload process.
Conditional processing makes use of four elements:
• The conditional instruction.
• The condition value.
• The condition ID.
• The condition map.
Conditional Instruction
When the EEPROM controller encounters a conditional
instruction during an upload sequence, it stores the instruction
in the EEPROM. When the EEPROM controller detects a
conditional instruction during a download sequence, it affects
the condition map as well as the outcome of conditional processing.
Condition Value
The condition value has a one to one correspondence to the
conditional instruction. Specifically, the condition value is the
value of the conditional instruction minus 0xB0. Therefore,
condition values have a range of 0 to 15. The EEPROM controller
uses condition values in conjunction with the condition map,
while the user uses a condition value to populate the EEPROM
load condition bit field of the register map with a condition ID.
Condition ID
The condition ID is the value stored in the 4-bit EEPROM load
condition bit field in the EEPROM section of the register map.
The EEPROM controller uses the condition ID in conjunction
with the condition map to determine which instructions to
execute or ignore during a download sequence.
Condition Map
The condition map is a table maintained by the EEPROM
controller consisting of a list of condition values. When the
EEPROM controller encounters a conditional instruction
during a download sequence, it determines the corresponding
condition value of the instruction (0 to 15). If the condition
value is nonzero, the EEPROM controller places the condition
value in the condition map. Conversely, if the condition value
is zero, the controller clears the condition map and applies
Condition 0. Condition 0 causes all subsequent instructions to
execute unconditionally (until the controller encounters a new
conditional instruction that causes conditional processing).
Conditional Processing
While executing a download sequence, the EEPROM controller
executes or skips instructions depending on the condition ID
and the contents of the condition map (except for the condi-
tional and end of data instructions, which always execute
unconditionally).
If the condition map is empty or the condition ID is zero, all
instructions execute unconditionally during download. However,
if the condition ID is nonzero and the condition map contains a
condition value matching the condition ID, the EEPROM
controller executes the subsequent instructions. Alternatively,
if the condition ID is nonzero but the condition map does not
contain a condition value matching the condition ID, the
EEPROM controller skips instructions until it encounters a
conditional instruction with a condition value of zero or a
condition value matching the condition ID.
Note that the condition map allows multiple conditions to exist
at any given moment. This multiconditional processing mecha-
nism enables the user to have one download instruction sequence
with many possible outcomes, depending on the value of the
condition ID and the order in which the controller encounters
conditional instructions. An example of the use of conditional
processing is shown in Table 32.
Data Sheet AD9542
Rev. 0 | Page 53 of 61
Table 32. Example Conditional Processing Sequence
Instruction Operation
0x00 to 0x7F A sequence of register transfer instructions
that execute unconditionally
0xB1 Apply Condition 1
0x00 to 0x7F A sequence of register transfer instructions
that execute only if the condition ID is 1
0xB2 Apply Condition 2
0xB3 Apply Condition 3
0x00 to 0x7F A sequence of register transfer instructions that
execute only if the condition ID is 1, 2, or 3
0x91 Calibrate the system clock PLL
0xB0 Clear condition map
0x80 Input/output update
0xFF Terminate sequence
Pause Instruction (0xFE)
The EEPROM controller only recognizes the pause instruction
during an upload sequence. Upon encountering a pause
instruction, the EEPROM controller enters an idle state, but
preserves the current value of the EEPROM address pointer.
One use of the pause instruction is for saving multiple, yet
distinct, values of the same AD9542 register, which is useful for
sequencing power-up conditions.
The pause instruction is also useful for executing an upload
sequence requiring more space than is available in the EEPROM
sequence registers in the EEPROM section of the register map
(see the EEPROM Upload section).
End of Data Instruction (0xFF)
When the EEPROM controller encounters an end of data
instruction during an upload sequence, it stores the instruction
in EEPROM along with the computed checksum, clears the
EEPROM address pointer, and then enters an idle state. When
encountered during a download sequence, however, the
EEPROM controller clears the EEPROM address pointer,
verifies the checksum, and then enters an idle state.
Note that during EEPROM downloads, condition instructions
always execute unconditionally.
MULTIDEVICE SUPPORT
Multidevice support enables multiple AD9542 devices to share
the contents of a single EEPROM. There are two levels of
multidevice support. Level 1 supports a configuration where
multiple AD9542 devices share a single EEPROM through a
dedicated I2C bus. Level 2 supports a configuration where
multiple AD9542 devices share a single EEPROM connected to
a common I2C bus that includes other I2C master devices.
Figure 51 and Figure 52 show the Level 1 and Level 2
configurations, respectively.
SDA
SCL
CPU
EEPROM
SCL SDA SCL
SDA
SCL SDA
AD9542
DEVICE 1
M1 M2
SCL SDA
AD9542
DEVICE 2
M1 M2
SCL SDA
2433
35
2433 35
15826-347
Figure 51. Level 1 Multidevice Configuration
AD9542
DEVICE 1
M1 M2SCL SDA
AD9542
DEVICE 2
M1 M2
SCL SDA
SDA
SCL
CPU
SDA
SCL
EEPROM
SCL
SDA
2433
35
2433 35
15826-348
Figure 52. Level 2 Multidevice Configuration
Multidevice Bus Arbitration
The EEPROM controller implements bus arbitration by
continuously monitoring the SDA and SCL bus signals for start
and stop conditions. The controller can determine whether the
bus is idle or busy. If the bus is busy, the EEPROM controller
delays its pending I2C transfer until a stop condition indicates
that the bus is available.
Bus arbitration is essential in cases where two I2C master
devices simultaneously attempt an I2C transfer. For example, if
one I2C master detects that SDA is Logic 0 when it is intended to be
Logic 1, it assumes that another I2C master is active and immedi-
ately terminates its own attempt to transfer data. Similarly, if
one I2C master detects that SCL is Logic 0 prior to entering a
start state, it assumes that another I2C master is active and stalls
its own attempt to drive the bus.
In either case, the prevailing I2C master completes its current
transaction before releasing the bus. Because the postponed I2C
master continuously monitors the bus for a stop condition, it
attempts to seize the bus and carry out the postponed transaction
on detection of such a stop condition.
The EEPROM controller includes an arbitration timer to optimize
the bus arbitration process. Specifically, when the EEPROM
controller postpones an I2C transfer as a result of detecting bus
contention, it starts the arbitration timer. If the EEPROM controller
fails to detect a stop condition within 255 SCL cycles, it attempts
to force another transaction. If the bus is still busy, the EEPROM
controller restarts the arbitration timer, and the process continues
until the EEPROM controller eventually completes the pending
transaction.
AD9542 Data Sheet
Rev. 0 | Page 54 of 61
Multidevice Configuration Example
Consider two AD9542 devices (Device 1 and Device 2) that
share a single EEPROM, and assume both devices have a
common PLL0 configuration but differing PLL1 configurations.
A template for an EEPROM sequence that accomplishes this
configuration is shown in Table 33. The sequence relies on
conditional processing to differentiate between Device 1 and
Device 2. Therefore, the user must program the condition ID
of both devices prior to executing an EEPROM download.
Specifically, the user must program the EEPROM load condition
bit field of Device 1 with a condition ID of 1 and Device 2 with
a condition ID of 2.
Table 33. Template for a Multidevice EEPROM Sequence
Instructions Comment
0x00 to 0x7F A sequence of register transfer instructions
associated with the PLL0 configuration
common to both devices
0xB1 Apply Condition 1
0x00 to 0x7F A sequence of register transfer instructions
associated with the PLL1 configuration
specific to Device 1
0xB0 Clear the condition map
0xB2 Apply Condition 2
0x00 to 0x7F
A sequence of register transfer instructions
associated with the PLL1 configuration
specific to Device 2
0xB0 Clear the condition map
0x80 Input/output update
0xFF End of sequence
Data Sheet AD9542
Rev. 0 | Page 55 of 61
SERIAL CONTROL PORT
The AD9542 serial control port is a flexible, synchronous serial
communications port that provides a convenient interface to
many industry-standard microcontrollers and microprocessors.
The AD9542 serial control port is compatible with most
synchronous transfer formats, including I²C, Motorola SPI, and
Intel SSR protocols. The serial control port allows read/write
access to the AD9542 register map.
The AD9542 uses the Analog Devices unified SPI protocol (see
the Analog Devices Serial Control Interface Standard). The
unified SPI protocol guarantees that all new Analog Devices
products using the unified protocol have consistent serial port
characteristics. The SPI port configuration is programmable via
Register 0x00.
Unified SPI differs from the SPI port found on older Analog
Devices products, such as the AD9557 and AD9558, in the
following ways:
• Unified SPI does not have byte counts. A transfer is
terminated when the CSB pin goes high. The W1 and W0
bits in the traditional SPI become the A12 and A13 bits of
the register address. This is similar to streaming mode in
the traditional SPI.
• The address ascension bit (Register 0x00) controls whether
register addresses are automatically incremented or
decremented regardless of the LSB/MSB first setting. In
traditional SPI, LSB first mode dictated auto-incrementing
and MSB first mode dictated auto-decrementing of the
register address.
• The first 16 register addresses of devices that adhere to the
unified serial port have a consistent structure.
SPI/I²C PORT SELECTION
Although the AD9542 supports both the SPI and I2C serial port
protocols, only one is active following power-up (as determined
by the M4 multifunction pin during the start-up sequence). The
only way to change the serial port protocol is to reset (or power
cycle) the device. See Table 27 for the I2C address assignments.
SPI SERIAL PORT OPERATION
Pin Descriptions
The serial clock (SCLK) pin serves as the serial shift clock. This
pin is an input. SCLK synchronizes serial control port read and
write operations. The rising edge SCLK registers write data bits,
and the falling edge registers read data bits. The SCLK pin
supports a maximum clock rate of 50 MHz.
The SPI port supports both 3-wire (bidirectional) and 4-wire
(unidirectional) hardware configurations and both MSB first
and LSB first data formats. Both the hardware configuration
and data format features are programmable. The 3-wire mode
uses the serial data input/output (SDIO) pin for transferring
data in both directions. The 4-wire mode uses the SDIO pin
for transferring data to the AD9542, and the SDO pin for
transferring data from the AD9542.
The chip select (CSB) pin is an active low control that gates read
and write operations. Assertion (active low) of the CSB pin
initiates a write or read operation to the AD9542 SPI port. The
user can transfer any number of data bytes in a continuous stream.
The register address is automatically incremented or decremented
based on the setting of the address ascension bit (Register 0x00).
The user must deassert the CSB pin following the last byte
transferred, thereby ending the stream mode. This pin is
internally connected to a 10 kΩ pull-up resistor. When CSB is
high, the SDIO and SDO pins enter a high impedance state.
Implementation Specific Details
The Analog Devices Serial Control Interface Standard provides
a detailed description of the unified SPI protocol and covers
items such as timing, command format, and addressing. The
unified SPI protocol defines the following device specific items:
• Analog Devices unified SPI protocol revision: 1.0
• Chip type: 0x5
• Product ID: 0x012
• Physical layer: 3-wire and 4-wire supported and 1.5 V,
1.8 V, and 2.5 V operation supported
• Optional single-byte instruction mode: not supported
• Data link: not used
• Control: not used
Communication Cycle—Instruction Plus Data
The unified SPI protocol consists of a two-part communication
cycle. The first part is a 16-bit instruction word coincident with
the first 16 SCLK rising edges. The second part is the payload,
the bits of which are coincident with SCLK rising edges. The
instruction word provides the AD9542 serial control port with
information regarding the payload. The instruction word
includes the R/W bit that indicates the direction of the payload
transfer (that is, a read or write operation). The instruction
word also indicates the starting register address of the first
payload byte.
Write
When the instruction word indicates a write operation, the
payload is written into the serial control port buffer of the
AD9542. Data bits are registered on the rising edge of SCLK.
Generally, it does not matter what data is written to blank
registers; however, it is customary to use 0s. Note that the user
must verify that all reserved registers within a specific range
have a default value of 0x00; however, Analog Devices makes
every effort to avoid having reserved registers with nonzero
default values.
Most of the serial port registers are buffered; therefore, data
written into buffered registers does not take effect immediately.
To transfer buffered serial control port contents to the registers
that actually control the device requires an additional operation,
an IO_UPDATE operation, implemented in one of two ways.
One is to write a Logic 1 to Register 0x0F, Bit 0 (this bit is an
AD9542 Data Sheet
Rev. 0 | Page 56 of 61
autoclearing bit). The other is to use an external signal via
an appropriately programmed multifunction pin. The user can
change as many register bits as desired before executing an
input/output update. The input/output update operation transfers
the buffer register contents to their active register counterparts.
Read
If the instruction word indicates a read operation, the next
N × 8 SCLK cycles clock out the data starting from the address
specified in the instruction word, where N is the number of
data bytes to read. Read data appears on the appropriate data
pin (SDIO or SDO) on the falling edge of SCLK. The user must
latch the read data on the rising edge of SCLK. Note that the
internal SPI control logic does not skip over blank registers
during a readback operation.
A readback operation takes data from either the serial control
port buffer registers or the active registers, as determined by
Register 0x01, Bit 5.
SPI Instruction Word (16 Bits)
The MSB of the 16-bit instruction word is R/W, which indicates
whether the ensuing operation is read or write. The next 15 bits
are the register address (A14 to A0), which indicates the starting
register address of the read/write operation (see Table 35). Note
that SPI controller ignores A14, treating it as Logic 0, because
the AD9542 has no register addresses requiring more than a
14-bit address word.
SPI MSB-/LSB-First Transfers
The AD9542 instruction word and payload can be transferred
MSB first or LSB first. The default for the AD9542 is MSB first.
To invoke LSB first mode, write a Logic 1 to Register 0x00, Bit 6.
Immediately after invoking LSB first mode, subsequent serial
control port operations are LSB first.
Address Ascension
If the address ascension bit (Register 0x00, Bit 5) is Logic 0,
serial control port register addressing decrements from the
specified starting address toward Address 0x00. If the address
ascension bit (Register 0x00, Bit 5) is Logic 1, serial control port
register addressing increments from the starting address toward
Address 0x3A3B. Reserved addresses are not skipped during
multibyte input/output operations; therefore, write the default
value to a reserved register and Logic 0s to unmapped registers.
Note that it is more efficient to issue a new write command than
to write the default value to more than two consecutive reserved
(or unmapped) registers.
Table 34. Streaming Mode (No Addresses Skipped)
Address Ascension Stop Sequence
Increment 0x0000 … 0x3A3B
Decrement 0x3A3B … 0x0000
Table 35. Serial Control Port, 16-Bit Instruction Word
MSB LSB
I15 I14 I13 I12 I11 I10 I9 I8 I7 I6 I5 I4 I3 I2 I1 I0
R/W A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
CSB
SCLK
DON'T CARE
SDIO A12A13A14R/W A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
DON'T CARE
DON'T CARE
DON'T CARE
16-BIT I NS TRUCT IO N HE ADE R REGISTER ( N) DATA RE GIS TER ( N – 1) DATA
15826-006
Figure 53. Serial Control Port Write—MSB First, Address Decrement, Two Bytes of Data
CSB
SCLK
SDIO
SDO
REGISTER (N) DATA16-BIT I NS TRUCTIO N HE ADE R REGISTER (N – 1) DATA REG ISTER (N – 2) DATA RE GIS TER ( N – 3) DATA
A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
DON'T CARE
DON' T CARE
DON' T CARE
DON'T
CARE
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
15826-007
Figure 54. Serial Control Port Read—MSB First, Address Decrement, Four Bytes of Data
t
S
DON' T CARE
DON' T CARE A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 D4 D3 D2 D1 D0
DON' T CARE
DON' T CARE
R/W
t
DS
t
DH
t
HIGH
t
LOW
t
CLK
t
C
CSB
SCLK
SDIO
15826-008
Figure 55. Timing Diagram for Serial Control Port Write—MSB First
Data Sheet AD9542
Rev. 0 | Page 57 of 61
DATA BI T N – 1DATA BI T N
CSB
SCLK
SDIO
SDO
t
DV
15826-009
Figure 56. Timing Diagram for Serial Control Port Register Read—MSB First
CSB
SCLK DON'T CARE DON' T CARE
16-BIT I NS TRUCT IO N HE ADE R REG ISTER (N) DATA RE GI S TER (N + 1) DATA
SDIO DON' T CARE
DON'T CARE A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 D1
D0R/W
A14
A13 D2 D3 D4 D5 D6 D7 D0 D1 D2 D3 D4 D5 D6 D7
15826-010
Figure 57. Serial Control Port Write—LSB First, Address Increment, Two Bytes of Data
CS
SCLK
SDIO
tHIGH tLOW
tCLK
tS
tDS
tDH
tC
BIT N BI T N + 1
15826-059
Figure 58. Serial Control Port Timing—Write
Table 36. Serial Control Port Timing
Parameter Description
t
DS
Setup time between data and the rising edge of SCLK
t
DH
Hold time between data and the rising edge of SCLK
t
CLK
Period of the clock
t
S
Setup time between the CSB falling edge and the SCLK rising edge (start of the communication cycle)
t
C
Setup time between the SCLK rising edge and CSB rising edge (end of the communication cycle)
t
HIGH
Minimum period that SCLK is in a logic high state
t
LOW
Minimum period that SCLK is in a logic low state
t
DV
SCLK to valid SDIO (see Figure 56)
AD9542 Data Sheet
Rev. 0 | Page 58 of 61
I²C SERIAL PORT OPERATION
The I2C interface is popular because it requires only two pins
and easily supports multiple devices on the same bus. Its main
disadvantage is its maximum programming speed of 400 kbps.
The AD9542 I²C port supports the 400 kHz fast mode as well as
the 100 kHz standard mode.
To support 1.5 V, 1.8 V, and 2.5 V I²C operation, the AD9542
does not strictly adhere to every requirement in the original I²C
specification. In particular, it does not support specifications such
as slew rate limiting and glitch filtering. Therefore, the AD9542
is I²C compatible, but not necessarily fully I²C compliant.
The AD9542 I²C port consists of a serial data line (SDA) and
a serial clock line (SCL). In an I²C bus system, the AD9542
connects to the serial bus (data bus SDA and clock bus SCL)
as a slave device; that is, the AD9542 does not generate an I²C
clock. The AD9542 uses direct 16-bit memory addressing rather
than 8-bit memory addressing, which is more common.
The AD9542 allows up to four unique slave devices to occupy
the I2C bus via a 7-bit slave address transmitted as part of an I2C
packet. Only the device with a matching slave address responds
to subsequent I2C commands. Table 37 lists the supported
device slave addresses.
I2C Bus Characteristics
A summary of the various I2C abbreviations appears in Table 37.
Table 37. I2C Bus Abbreviation Definitions
Abbreviation Definition
S Start
Sr Repeated start
P Stop
A Acknowledge
A
Nonacknowledge
W Write
R Read
An example of valid data transfer appears in Figure 59. One
clock pulse is required for each data bit transferred. The data on
the SDA line must be stable during the high period of the clock.
The high or low state of the data line can change only when the
clock signal on the SCL line is low.
DATA LINE
STABLE;
DATA VALI D
CHANGE
OF DATA
ALLOWED
SDA
SCL
15826-012
Figure 59. Valid Bit Transfer
Start and stop functionality appears in Figure 60. The start
condition is a high to low transition on the SDA line while SCL
is high. The master always generates the start condition to
initialize a data transfer. The stop condition is a low to high
transition on the SDA line while SCL is high. The master always
generates the stop condition to terminate a data transfer. The
SDA line must always transfer eight bits (one byte). Each byte
must be followed by an acknowledge bit; bytes are sent MSB first.
The acknowledge bit (A) is the ninth bit attached to any 8-bit
data byte. An acknowledge bit is always generated by the
receiver to inform the transmitter that the byte has been
received. Acknowledgement consists of pulling the SDA line
low during the ninth clock pulse after each 8-bit data byte.
The nonacknowledge bit (A) is the ninth bit attached to any
8-bit data byte. A nonacknowledge bit is always generated by
the receiver to inform the transmitter that the byte has not been
received. Nonacknowledgment consists of leaving the SDA line
high during the ninth clock pulse after each 8-bit data byte.
After issuing a nonacknowledge bit, the AD9542 I²C state
machine goes into an idle state.
Data Transfer Process
The master initiates data transfer by asserting a start condition,
which indicates that a data stream follows. All I²C slave devices
connected to the serial bus respond to the start condition.
The master then sends an 8-bit address byte over the SDA line,
consisting of a 7-bit slave address (MSB first) plus a R/W bit.
This bit determines the direction of the data transfer, that is,
whether data is written to or read from the slave device (Logic 0
indicates write, and Logic 1 indicates read).
The peripheral whose address corresponds to the transmitted
address responds by sending an acknowledge bit. All other
devices on the bus remain idle while the selected device waits
for data to be read from or written to it. If the R/W bit is Logic 0,
the master (transmitter) writes to the slave device (receiver).
If the R/W bit is Logic 1, the master (receiver) reads from the
slave device (transmitter). The format for these commands
appears in the Data Transfer Format section.
Data is then sent over the serial bus in the format of nine clock
pulses, one data byte (eight bits) from either master (write mode)
or slave (read mode), followed by an acknowledge bit from the
receiving device. The protocol allows a data transfer to consist
of any number of bytes (that is, the payload size is unrestricted).
In write mode, the first two data bytes immediately after the
slave address byte are the internal memory (control registers)
address bytes (the higher address byte first). This addressing
scheme gives a memory address of up to 216 − 1 = 65,535. The
data bytes after these two memory address bytes are register
data written to or read from the control registers. In read mode,
the data bytes following the slave address byte consist of register
data written to or read from the control registers.
When all the data bytes are read or written, stop conditions are
established. In write mode, the master device (transmitter)
asserts a stop condition to end data transfer during the clock
pulse following the acknowledge bit for the last data byte from the
slave device (receiver). In read mode, the master device (receiver)
receives the last data byte from the slave device (transmitter)
but does not pull SDA low during the ninth clock pulse (a
Data Sheet AD9542
Rev. 0 | Page 59 of 61
nonacknowledge bit). By receiving the nonacknowledge bit, the
slave device knows that the data transfer is finished and enters
idle mode. The master device then takes the data line low
during the low period before the 10th clock pulse, and high
during the 10th clock pulse to assert a stop condition.
A start condition can be used instead of a stop condition.
Furthermore, a start or stop condition can occur at any time,
and partially transferred bytes are discarded.
SDA
START CONDITION STOP CONDITION
SCL
SP
15826-013
Figure 60. Start and Stop Conditions
12 89123 TO 73 TO 7 89
10
SDA
SCL
S
MSB
ACK FROM
SLAVE RECEIVER
ACK FROM
SLAVE RECEIVER
P
15826-014
Figure 61. Acknowledge Bit
12 89123 TO 73 TO 7 8910
ACK FROM
SLAVE RECEIVER ACK FROM
SLAVE RECEIVER
SDA
SCL
S
MSB
P
15826-015
Figure 62. Data Transfer Process (Master Write Mode, 2-Byte Transfer)
12 89123 TO 73 TO 7 8910
ACK FROM
MASTER RECEIVER NONACK FROM
MASTER RECEIVER
SDA
SCL
SP
15826-016
Figure 63. Data Transfer Process (Master Read Mode, 2-Byte Transfer), First Acknowledge From Slave
AD9542 Data Sheet
Rev. 0 | Page 60 of 61
Data Transfer Format
The write byte format is used to write a register address to the
RAM starting from the specified RAM address (see Table 38).
The send byte format is used to set up the register address for
subsequent reads (see Table 39). The receive byte format is used
to read the data byte(s) from RAM starting from the current
address (see Table 40). The read byte format is the combined
format of the send byte and the receive byte (see Table 41).
Table 38. Write Byte Format
S Slave
address
WE A RAM address high byte A RAM address low byte A RAM
Data 0
A RAM
Data 1
A RAM
Data 2
A P
Table 39. Send Byte Format
S Slave address WE A RAM address high byte A RAM address low byte A P
Table 40. Receive Byte Format
S Slave address R A RAM Data 0 A RAM Data 1 A RAM Data 2 AE P
Table 41. Read Byte Format
S Slave
address
WE A RAM address
high byte
A RAM address
low byte
A Sr Slave
address
R A RAM
Data 0
A RAM
Data 1
A RAM
Data 2
AE P
I²C Serial Port Timing
SSr SP
S
D
A
SCL
tSP
tHD; STA
tSU; STA
tSU; DAT
tHD; DAT
tHD; STA tSU; STO
tBUF
tR
tF
tR
tF
tHIGH
tLOW
15826-017
Figure 64. I²C Serial Port Timing
Table 42. IC Timing Definitions
Parameter Description
fSCL Serial clock
tBUF Bus free time between stop and start conditions
tHD; STA Repeated hold time start condition
tSU; STA Repeated start condition setup time
tSU; STO Stop condition setup time
tHD; DAT Data hold time
tSU; DAT Data setup time
tLOW SCL clock low period
tHIGH SCL clock high period
tR Minimum/maximum receive SCL and SDA rise time
tF Minimum/maximum receive SCL and SDA fall time
tSP Pulse width of voltage spikes that must be suppressed by the input filter
Data Sheet AD9542
Rev. 0 | Page 61 of 61
OUTLINE DIMENSIONS
COMPLIANT TO JEDEC STANDARDS MO-220-WKKD-4.
1
0.50
BSC
BOTTOM VIEW
TOP VIEW
PIN 1
INDICATOR
48
13
24
36
37
5.70
5.60 SQ
5.50
0.50
0.40
0.30
0.80
0.75
0.70 0.05 MAX
0.02 NOM
0.203 REF
COPLANARITY
0.08
0.30
0.25
0.18
02-29-2016-A
7.10
7.00 SQ
6.90
0.20 MIN
5.50 REF
END VIEW
EXPOSED
PAD
PKG-004452
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CONFIGURATION AND
FUNCTION DESCRIPTIONS
SECTION OF THIS DATA SHEET.
PIN 1
INDICATOR AREA OPTIONS
(SEE DETAIL A)
DETAIL A
(JEDEC 95)
SEATING
PLANE
Figure 65. 48-Lead Lead Frame Chip Scale Package [LFCSP]
7 mm × 7 mm Body and 0.75 mm Package Height
(CP-48-13)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD9542BCPZ −40°C to +85°C 48-Lead Lead Frame Chip Scale Package [LFCSP) CP-48-13
AD9542BCPZ-REEL7 −40°C to +85°C 48-Lead Lead Frame Chip Scale Package [LFCSP] CP-48-13
AD9542/PCBZ Evaluation Board
1 Z = RoHS Compliant Part.
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
©2017 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D15826-0-9/17(0)