SM802140
ClockWorks
TM
644.53125MHz LVDS
Ultra-Low Jitter,
Frequency Synthesizer
ClockWorks is a trademark of Micrel, Inc
RotaryWave is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
November 2011 1
M9999-012111-A
hbwhelp@micrel.com
or (408) 955-1690
General Description
The SM802140 is a member of the ClockWorks family of
devices from Micrel and provides an extremely low-noise
timing solution for clock signals. It is based upon a unique
patented RotaryWave
®
architecture that provides very low
phase noise.
The device operates from a 3.3V or 2.5V power supply
and synthesizes four Differential LVDS clocks at
644.53125MHz
The SM802140 accepts a 20.141601MHz crystal input.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
Generates four LVDS clocks output at 644.53125MHz
2.5V or 3.3V operating range
Typical phase jitter @ 644MHz
(1.875MHz to 20MHz): 114 fs (typical) at 3.3V
Industrial temperature range
Green, RoHS, and PFOS compliant
Available in 24-pin 4mm × 4mm QFN package
Applications
40GbE
Serial PMD clock
FPGA Transceiver clock
___________________________________________________________________________________________________________
Block Diagram
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Ordering Information
Part Number Marking Shipping Temperature Range Package
SM802140UMG 802140 Tube –40°C to +85°C 24-Pin QFN
SM802140UMGTR 802140 Tape and Reel –40°C to +85°C 24-Pin QFN
Note:
1. Devices are Green, RoHS, and PFOS compliant.
Pin Configuration
24-Pin QFN
(Top View)
Pin Description
Pin Number
Pin Name
Pin Type
Pin Level
Pin Function
3, 4
16, 17
20, 21
23, 24
/Q3, Q3
/Q0, Q0
/Q1, Q1
/Q2, Q2
O, (DIFF) LVDS Differential Clock Outputs at 644.53125MHz
1 VDDO2 PWR Power Supply for Outputs Q2 and Q3
2 VSSO2 PWR Power Supply Ground for Outputs Q2 and Q3
5 PLL_BYPASS I, (SE) LVCMOS
Bypasses the PLL and Switches the REF_IN or
XTAL Frequency to all Outputs
1 = Bypass PLL, output is XTAL or REF_IN
0 = PLL Mode, 45KΩ pull-down
6 XTAL_SEL I, (SE) LVCMOS Selects PLL Reference Input Mode
0 = REF_IN, 1 = XTAL, 45KΩ pull-up
7, 12, 15, 19 TEST I, (SE) LVCMOS Test Pins. Do Not Connect These Pins to Anything
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Pin Description (Continued)
8 VDD PWR Power Supply
9 REF_IN I, (SE) LVCMOS Reference Clock Input
10 XIN I, (SE) crystal Crystal Input, no load caps needed.
See Fig. 6.
11 XOUT O, (SE) crystal Crystal Output, no load caps needed.
See Fig. 6.
13 VSS I, (SE) This Pin is not a Power Supply Ground, but MUST
be Tied to VSS
14 VSS
(Exposed
Pad) PWR Power Supply Ground. The exposed pad must be
connected to the VSS ground plane.
18 VDDO1 PWR Power Supply for Outputs Q0 and Q1
22 VSSO1 PWR Power Supply Ground for Outputs Q0 and Q1
Truth Table
Application Information
Crystal Layout
Keep the layers under the crystal as open as possible
and do not place switching signals or noisy supplies
under the crystal.
Crystal load capacitance is built inside the die so no
external capacitance is needed. See the Selecting a
Quartz crystal for the Clockworks Flex I Family of
Precision Synthesizers application note for further
details.
Contact Micrel’s HBW applications group if you need
assistance on selecting a suitable crystal for your
application at hbwhelp@micrel.com
PLL_BYPASS
XTAL_SE
L
INPUT
OUTPUT
0 − − PLL
1 − − XTAL/REF_IN
− 0 REF_IN −
− 1 XTAL −
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Absolute Maximum Ratings
(1)
Supply Voltage (V
DD
, V
DDO1/2
) .................................... +4.6V
Input Voltage (V
IN
). ............................ –0.50V to V
DD
+ 0.5V
Lead Temperature (soldering, 20sec.) ...................... 260°C
Case Temperature ................................................... 115°C
Storage Temperature (T
s
) .......................... –65°C to +150°
Operating Ratings
(2)
Supply Voltage (V
DD
, V
DDO1/2
) .............. +2.375V to +3.465V
Ambient Temperature (T
A
)......................... –40°C to +85°C
Junction Thermal Resistance
(3)
QFN (θ
JA
)
Still-Air....................................................... 50°C/W
QFN (ψ
JB
)
Junction-to-Board ...................................... 32°C/W
DC Electrical Characteristics
(4)
V
DD
= V
DDO
= 3.3V ±5% or 2.5V ±5%
V
DD
= 3.3V ±5%, V
DDO
1/2
= 3.3V ±5% or 2.5V ±5%
T
A
= −40°C to +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
V
DD
, V
DDO
2.5V Operating Voltage 2.375 2.5 2.625 V
V
DD
, V
DDO
3.3V Operating Voltage 3.135 3.3 3.465 V
I
DD
Supply current V
DD
+ V
DDO
Outputs open 644MHz - 4 Diff LVDS outputs - 204 240 mA
LVCMOS INPUT (XTAL_SEL, PLL_Bypass) DC Electrical Characteristics
(4)
V
DD
= 3.3V ±5%, or 2.5V ±5%, T
A
= −40°C to +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
V
IH
Input High Voltage
2 V
DD
+ 0.3 V
V
IN
Input Low Voltage
−0.3 0.8 V
I
IH
Input High Current V
DD
= V
IN
= 3.465V
150 µA
I
IL
Input Low Current V
DD
= 3.465V, V
IN
= 0V
−150 µA
LVDS OUTPUT DC Electrical Characteristics
(4)
V
DD
= V
DDO1/2
= 3.3V ±5% or 2.5V ±5%
V
DD
= 3.3V ±5%, V
DDO1/2
= 3.3V ±5% or 2.5V ±5%
T
A
= −40°C to +85°C. R
L
= 100Ω across Q and /Q.
Symbol Parameter Condition Min Typ Max Units
V
OD
Differential Output Voltage
Figure 1
275 350 475 mV
∆V
OD
V
OD
Magnitude Change
40 mV
V
OS
Offset Voltage
1.15 1.25 1.50 V
∆V
OS
V
OS
Magnitude Change
50 mV
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Crystal Characteristics
Parameter
Condition
Min.
Typ.
Max.
Units
Mode of Oscillation 10pF Load
(6)
Fundamental, Parallel Resonant
Frequency 20.141601 MHz
Equivalent Series Resistance (ESR) 50 Ω
Shunt Capacitor, C0 1 5 pF
Correlation Drive Level 10 100 uW
AC Electrical Characteristics
(4, 5, 6)
V
DD
= V
DDO
1/2
= 3.3V ±5% or 2.5V ±5%
V
DD
= 3.3V ±5%, V
DDO
1/2
= 3.3V ±5% or 2.5V ±5%
T
A
= −40°C to +85°C. R
L
= 100Ω across Q and /Q
Symbol
Parameter
Condition
Min.
Typ.
Max.
Units
F
OUT
Output Frequency 644.53125 MHz
T
R
/T
F
LVDS Output Rise/Fall Time 20% – 80% 80 175 350 ps
ODC Output Duty Cycle 48 50 52 %
T
LOCK
PLL Lock Time 20 ms
T
jit
(∅) RMS Phase Jitter
Integration Range (1.875MHz – 20MHz)
Integration Range (12kHz – 20MHz)
114
293
fs
Spurious Noise Components 20.141MHz reference
Reference 2
nd
harmonic
Reference 3
rd
harmonic -82
-78
-85 dBc
Note:
1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied
at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
3. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
4. The circuit is designed to meet the AC and DC specifications shown in the above table(s) after thermal equilibrium has been established.
5. All phase noise measurements were taken with an Agilent 5052B phase noise system.
6. See Application note, “Selecting a Quartz crystal for the Clockworks Flex I Family of Precision Synthesizers” for further details.
7. Measured using 20.141MHz crystal as the input reference source. If using an external reference input, use a low phase noise source. With an
external reference, the phase noise will follow the input source phase noise up to about 1MHz.
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Phase Noise Plots
Phase Noise Plot: 644.53125MHz, 12KHz - 20MHz 293 Fs
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Phase Noise Plot: 644.53125MHz, 1.875MHz - 20MHz 114 Fs
Figure 1. Duty Cycle
Ti
ming
Figure 2. All Outputs Rise/Fall Time
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Figure 3. RMS Phase/Noise/Jitter
Figure 4. LVDS
Output Load and Test Circuit
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Figure 5. Crystal Input Interface
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Package Information
24-Pin QFN
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical
implant into the body or (b) support or sustain life, and whose failure to perform can be reason
ably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk a
nd Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2011 Micrel, Incorporated.
