Super Sequencer and Monitor with
Nonvolatile Fault Recording
ADM1168
Rev. 0
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FEATURES
Complete supervisory and sequencing solution for up to
8 supplies
16 event deep black box nonvolatile fault recording
8 supply fault detectors enable supervision of supplies to
<0.5% accuracy at all voltages at 25°C
<1.0% accuracy across all voltages and temperatures
4 selectable input attenuators allow supervision of supplies to
14.4 V on VH
6 V on VP1 to VP3 (VPx)
4 dual-function inputs, VX1 to VX4 (VXx)
High impedance input to supply fault detector with
thresholds between 0.573 V and 1.375 V
General-purpose logic input
8 programmable driver outputs, PDO1 to PDO8 (PDOx)
Open-collector with external pull-up
Push/pull output, driven to VDDCAP or VPx
Open-collector with weak pull-up to VDDCAP or VPx
Internally charge-pumped high drive for use with external
NFET (PDO1 to PDO6 only)
Sequencing engine (SE) implements state machine control of
PDO outputs
State changes conditional on input events
Enables complex control of boards
Power-up and power-down sequence control
Fault event handling
Interrupt generation on warnings
Watchdog function can be integrated in SE
Program software control of sequencing through SMBus
Device powered by the highest of VPx, VH for improved
redundancy
User EEPROM: 256 bytes
Industry-standard 2-wire bus interface (SMBus)
Guaranteed PDO low with VH, VPx = 1.2 V
Available in 32-lead, 7 mm × 7 mm LQFP
APPLICATIONS
Central office systems
Servers/routers
Multivoltage system line cards
DSP/FPGA supply sequencing
In-circuit testing of margined supplies
FUNCTIONAL BLOCK DIAGRAM
PDO7
PDO8
PDOGND
VDD
ARBITRATOR
GND
VCCP
VX1
VX2
VX3
VX4
VP1
VP2
VP3
VH
AGND
V
DDCAP
PROGRAMMABLE
RESET
GENERATORS
(SFDs)
DUAL-
FUNCTION
INPUTS
(LOGIC INPUTS
OR
SFDs)
SEQUENCING
ENGINE
CONFIGURABLE
OUTPUT
DRIVERS
(LV CAPABLE
OF DRIVING
LOGIC SIGNALS)
PDO1
PDO2
PDO3
PDO4
PDO5
PDO6
SD
A
SCL
A
1
A
0
SMBus
INTERFACE
REFOUT REFGND
VREF
ADM1168
CONFIGURABLE
OUTPUT
DRIVERS
(HV CAPABLE OF
DRIVING GATES
OF NFET)
EEPROMFAULT RECORDING
09474-001
Figure 1.
GENERAL DESCRIPTION
The ADM1168 Super Sequencer® is a configurable supervisory/
sequencing device that offers a single-chip solution for supply
monitoring and sequencing in multiple supply systems.
The device also provides up to eight programmable inputs for
monitoring undervoltage faults, overvoltage faults, or out-of-window
faults on up to eight supplies. In addition, eight programmable
outputs can be used as logic enables. Six of these programmable
outputs can also provide up to a 12 V output for driving the gate
of an NFET that can be placed in the path of a supply.
The logical core of the device is a sequencing engine. This state
machine-based construction provides up to 63 different states.
This design enables very flexible sequencing of the outputs based
on the condition of the inputs.
A block of nonvolatile EEPROM is available that can be used to
store user-defined information and may also be used to hold a
number of fault records that are written by the sequencing engine
defined by the user when a particular fault or sequence occurs.
The ADM1168 is controlled via configuration data that can be
programmed into an EEPROM. The whole configuration can be
programmed using an intuitive GUI-based software package
provided by Analog Devices, Inc.
For more information about the ADM1168 register map, refer
to the AN-721 Application Note.
ADM1168
Rev. 0 | Page 2 of 28
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Detailed Block Diagram .................................................................. 3
Specifications..................................................................................... 4
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution.................................................................................. 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Powering the ADM1168................................................................ 10
Inputs................................................................................................ 11
Supply Supervision..................................................................... 11
Programming the Supply Fault Detectors............................... 11
Input Comparator Hysteresis.................................................... 12
Input Glitch Filtering ................................................................. 12
Supply Supervision with VXx Inputs....................................... 13
VXx Pins as Digital Inputs ........................................................ 13
Outputs ............................................................................................ 14
Supply Sequencing Through Configurable Output Drivers. 14
Default Output Configuration.................................................. 14
Sequencing Engine......................................................................... 15
Overview ..................................................................................... 15
Warnings...................................................................................... 15
SMBus Jump (Unconditional Jump)........................................ 15
Sequencing Engine Application Example............................... 16
Fault and Status Reporting........................................................ 17
Nonvolatile Black Box Fault Recording................................... 17
Black Box Writes with No External Supply ............................ 18
Applications Diagram.................................................................... 19
Communicating with the ADM1168........................................... 20
Configuration Download at Power-Up................................... 20
Updating the Configuration ..................................................... 20
Updating the Sequencing Engine............................................. 21
Internal Registers........................................................................ 21
EEPROM ..................................................................................... 21
Serial Bus Interface..................................................................... 22
SMBus Protocols for RAM and EEPROM.............................. 24
Write Operations........................................................................ 24
Read Operations......................................................................... 25
Outline Dimensions ....................................................................... 27
Ordering Guide .......................................................................... 27
REVISION HISTORY
4/11—Revision 0: Initial Version
ADM1168
Rev. 0 | Page 3 of 28
DETAILED BLOCK DIAGRAM
GPI SIGNAL
CONDITIONING
SFD
GPI SIGNAL
CONDITIONING
SFD
SFD
SFD
SELECTABLE
ATTENUATOR
SELECTABLE
ATTENUATOR
DEVICE
CONTROLLER
OSC
EEPROM
SDA SCL A1 A0
SMBus
INTERFACE
ADM1168
CONFIGURABLE
OUTPUT DRIVER
(HV)
PDO1
PDO2
PDOGND
PDO3
GND
PDO4
PDO5
CONFIGURABLE
OUTPUT DRIVER
(HV)
PDO6
CONFIGURABLE
OUTPUT DRIVER
(LV)
PDO7
CONFIGURABLE
OUTPUT DRIVER
(LV)
PDO8
SEQUENCING
ENGINE
VX2
VX3
VP2
VP3
VH
VP1
VX1
AGND
VX4
VDD
ARBITRATOR
VCCP
REG 5.25V
CHARGE PUMP
REFOUT REFGND
VREF
VDDCAP
09474-002
FAULT
RECORDING
Figure 2. Detailed Block Diagram
ADM1168
Rev. 0 | Page 4 of 28
SPECIFICATIONS
VH = 3.0 V to 14.4 V1, VPx = 3.0 V to 6.0 V1, TA = −40°C to +85°C, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
POWER SUPPLY ARBITRATION
VH, VPx 3.0 V Minimum supply required on one of the VH, VPx pins
VPx 6.0 V Maximum VDDCAP = 5.1 V typical
VH 14.4 V VDDCAP = 4.75 V
VDDCAP 2.7 4.75 5.4 V Regulated LDO output
CVDDCAP 10 μF Minimum recommended decoupling capacitance
POWER SUPPLY
Supply Current, IVH, IVPx 4.2 6 mA VDDCAP = 4.75 V, PDO1 to PDO8 off
Additional Currents
All PDOx FET Drivers On 1 mA VDDCAP = 4.75 V, PDO1 to PDO6 loaded with 1 μA each,
PDO7 to PDO8 off
Current Available from VDDCAP 2 mA Maximum additional load that can be drawn from all PDO
pull-ups to VDDCAP
EEPROM Erase Current 10 mA 1 ms duration only, VDDCAP = 3 V
SUPPLY FAULT DETECTORS
VH Pin
Input Impedance 52 kΩ
Input Attenuator Error ±0.05 % Midrange and high range
Detection Ranges
High Range 6 14.4 V
Midrange 2.5 6 V
VPx Pins
Input Impedance 52 kΩ
Input Attenuator Error ±0.05 % Low range and midrange
Detection Ranges
Midrange 2.5 6 V
Low Range 1.25 3 V
Ultralow Range 0.573 1.375 V No input attenuation error
VXx Pins
Input Impedance 1 MΩ
Detection Ranges
Ultralow Range 0.573 1.375 V No input attenuation error
Absolute Accuracy ±1 % Internal reference VREF error + DAC nonlinearity +
comparator offset error
Threshold Resolution 8 Bits
Digital Glitch Filter 0 μs Minimum programmable filter length
100 μs Maximum programmable filter length
REFERENCE OUTPUT
Reference Output Voltage 2.043 2.048 2.053 V No load
Load Regulation −0.25 mV Sourcing current
0.25 mV Sinking current
Minimum Load Capacitance 1 μF Capacitor required for decoupling, stability
PSRR 60 dB DC
ADM1168
Rev. 0 | Page 5 of 28
Parameter Min Typ Max Unit Test Conditions/Comments
PROGRAMMABLE DRIVER OUTPUTS
High Voltage (Charge Pump) Mode
(PDO1 to PDO6)
Output Impedance 500 kΩ
VOH 11 12.5 14 V IOH = 0 μA
10.5 12 13.5 V IOH = 1 μA
IOUTAVG 20 μA 2 V < VOH < 7 V
Standard (Digital Output) Mode
(PDO1 to PDO8)
VOH 2.4 V VPU (pull-up to VDDCAP or VPx) = 2.7 V, IOH = 0.5 mA
4.5 V VPU to VPx = 6.0 V, IOH = 0 mA
V
PU − 0.3 V VPU ≤ 2.7 V, IOH = 0.5 mA
VOL 0 0.50 V IOL = 20 mA
IOL2 20 mA Maximum sink current per PDO pin
ISINK2 60 mA Maximum total sink for all PDO pins
RPULL-UP 16 20 29 kΩ Internal pull-up
ISOURCE (VPx)2 2 mA Current load on any VPx pull-ups, that is, total source
current available through any number of PDO pull-up
switches configured onto any one VPx pin
Three-State Output Leakage Current 10 μA VPDO = 14.4 V
Oscillator Frequency 90 100 110 kHz All on-chip time delays derived from this clock
DIGITAL INPUTS (VXx, A0, A1)
Input High Voltage, VIH 2.0 V Maximum VIN = 5.5 V
Input Low Voltage, VIL 0.8 V Maximum VIN = 5.5 V
Input High Current, IIH −1 μA VIN = 5.5 V
Input Low Current, IIL 1 μA VIN = 0 V
Input Capacitance 5 pF
Programmable Pull-Down Current,
IPULL-DOWN
20 μA VDDCAP = 4.75 V, TA = 25°C, if known logic state is required
SERIAL BUS DIGITAL INPUTS (SDA, SCL)
Input High Voltage, VIH 2.0 V
Input Low Voltage, VIL 0.8 V
Output Low Voltage, VOL2 0.4 V IOUT = −3.0 mA
SERIAL BUS TIMING See Figure 27
Clock Frequency, fSCLK 400 kHz
Bus Free Time, tBUF 1.3 μs
Start Setup Time, tSU;STA 0.6 μs
Stop Setup Time, tSU;STO 0.6 μs
Start Hold Time, tHD;STA 0.6 μs
SCL Low Time, tLOW 1.3 μs
SCL High Time, tHIGH 0.6 μs
SCL, SDA Rise Time, tr 300 ns
SCL, SDA Fall Time, tf 300 ns
Data Setup Time, tSU;DAT 100 ns
Data Hold Time, tHD;DAT 250 ns
Input Low Current, IIL 1 μA VIN = 0 V
SEQUENCING ENGINE TIMING
State Change Time 10 μs
1 At least one of the VH, VPx pins must be ≥3.0 V to maintain the device supply on VDDCAP.
2 Specification is not production tested but is supported by characterization data at initial product release.
ADM1168
Rev. 0 | Page 6 of 28
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Voltage on VH Pin 16 V
Voltage on VPx Pins 7 V
Voltage on VXx Pins −0.3 V to +6.5 V
Voltage on A0, A1 Pins −0.3 V to +7 V
Voltage on REFOUT Pin 5 V
Voltage on VDDCAP, VCCP Pins 6.5 V
Voltage on PDOx Pins 16 V
Voltage on SDA, SCL Pins 7 V
Voltage on GND, AGND, PDOGND,
REFGND Pins
−0.3 V to +0.3 V
Input Current at Any Pin ±5 mA
Package Input Current ±20 mA
Maximum Junction Temperature (TJ max) 150°C
Storage Temperature Range −65°C to +150°C
Lead Temperature, Soldering Vapor Phase, 60 sec 215°C
ESD Rating, All Pins 2000 V
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type θJA Unit
32-Lead LQFP 54 °C/W
ESD CAUTION
ADM1168
Rev. 0 | Page 7 of 28
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NC = NO CONNECT.
DO NOT CONNECT TO THIS PIN.
12
25
32
8
9
17
16
4
VX1
VX2
VX3
VX4
VP1
VP2
VP3
VH
PDO1
PDO2
PDO3
PDO4
PDO5
PDO6
PDO7
PDO8
GND
VDDCAP
SDA
SCL
A1
A0
VCCP
PDOGN
D
AGND
REFGND
NC
REFOUT
NC
NC
NC
NC
PIN 1
INDICATOR
ADM1168
TOP VIEW
(Not to Scale)
09474-003
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 to 4 VX1 to VX4 High Impedance Inputs to Supply Fault Detectors. Fault thresholds can be set from 0.573 V to 1.375 V.
Alternatively, these pins can be used as general-purpose digital inputs.
5 to 7 VP1 to VP3 Low Voltage Inputs to Supply Fault Detectors. Three input ranges can be set by altering the input attenuation
on a potential divider connected to these pins, the output of which connects to a supply fault detector.
These pins allow thresholds from 2.5 V to 6 V, from 1.25 V to 3 V, and from 0.573 V to 1.375 V.
8 VH High Voltage Input to Supply Fault Detectors. Three input ranges can be set by altering the input attenuation
on a potential divider connected to this pin, the output of which connects to a supply fault detector.
This pin allows thresholds from 6 V to 14.4 V and from 2.5 V to 6 V.
9 AGND1 Ground Return for Input Attenuators.
10 REFGND1 Ground Return for On-Chip Reference Circuits.
11, 13 to 16 NC No Connect.
12 REFOUT
Reference Output, 2.048 V. Note that a capacitor must always be connected between this pin and REFGND.
A 10 μF capacitor is recommended for this purpose.
17 to 24 PDO8 to PDO1 Programmable Output Drivers.
25 PDOGND1 Ground Return for Output Drivers.
26 VCCP
Central Charge-Pump Voltage of 5.25 V. A reservoir capacitor must be connected between this pin and
GND. A 10 μF capacitor is recommended for this purpose.
27 A0 Logic Input. This pin sets the seventh bit of the SMBus interface address.
28 A1 Logic Input. This pin sets the sixth bit of the SMBus interface address.
29 SCL SMBus Clock Pin. Bidirectional open drain requires external resistive pull-up.
30 SDA SMBus Data Pin. Bidirectional open drain requires external resistive pull-up.
31 VDDCAP
Device Supply Voltage. Linearly regulated from the highest of the VPx and VH pins to a typical of 4.75 V.
A capacitor must be connected between this pin and GND. A 10 μF capacitor is recommended for
this purpose.
32 GND1 Supply Ground.
1 In a typical application, all ground pins are connected together.
ADM1168
Rev. 0 | Page 8 of 28
TYPICAL PERFORMANCE CHARACTERISTICS
6
0
1
2
3
4
5
0654321
V
VP1
(V)
V
VDDCAP
(V)
09474-050
Figure 4. VVDDCAP vs. VVP1
6
0
1
2
3
4
5
011412108642
V
VH
(V)
V
VDDCAP
(V)
6
09474-051
Figure 5. VVDDCAP vs. VVH
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0123456
V
VP1
(V)
I
VP1
(mA)
09474-052
Figure 6. IVP1 vs. VVP1 (VP1 as Supply)
180
160
140
120
100
80
60
40
20
0
0123456
V
VP1
(V)
I
VP1
(µA)
09474-053
Figure 7. IVP1 vs. VVP1 (VP1 Not as Supply)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
011412108642
V
VH
(V)
I
VH
(mA)
6
09474-054
Figure 8. IVH vs. VVH (VH as Supply)
350
300
250
200
150
100
50
0
0654321
V
VH
(V)
I
VH
(µA)
09474-055
Figure 9. IVH vs. VVH (VH Not as Supply)
ADM1168
Rev. 0 | Page 9 of 28
14
12
10
8
6
4
2
0
0 15.012.510.07.55.02.5
I
LOAD
(µA)
CHARGE-PUMPED V
PDO1
(V)
09474-056
Figure 10. Charge-Pumped VPDO1 (FET Drive Mode) vs. ILOAD
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0654321
I
LOAD
(mA)
V
PDO1
(V)
VP1 = 5V
VP1 = 3V
09474-057
Figure 11. VPDO1 (Strong Pull-Up to VPx) vs. ILOAD
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
065040302010
I
LOAD
(µA)
V
PDO1
(V)
0
VP1 = 5V
VP1 = 3V
09474-058
Figure 12. VPDO1 (Weak Pull-Up to VPx) vs. ILOAD
2.058
2.038
2.043
2.048
2.053
–40 –20 0 20 40 60 10080
TEMPERATURE (°C)
REFOUT (V)
VP1 = 3.0V
VP1 = 4.75V
09474-061
Figure 13. REFOUT vs. Temperature
ADM1168
Rev. 0 | Page 10 of 28
POWERING THE ADM1168
The ADM1168 is powered from the highest voltage input on either
the positive-only supply inputs (VPx) or the high voltage supply
input (VH). This technique offers improved redundancy because
the device is not dependent on any particular voltage rail to keep
it operational. The same pins are used for supply fault detection
(see the Supply Supervision section). A VDD arbitrator on the
device chooses which supply to use. The arbitrator can be
considered an OR’ing of four low dropout regulators (LDOs)
together. A supply comparator chooses the highest input to
provide the on-chip supply. There is minimal switching loss
with this architecture (~0.2 V), resulting in the ability to power
the ADM1168 from a supply as low as 3.0 V. Note that the supply
on the VXx pins cannot be used to power the device.
An external capacitor to GND is required to decouple the on-chip
supply from noise. This capacitor should be connected to the
VDDCAP pin, as shown in Figure 14. The capacitor has another
use during brownouts (momentary loss of power). Under these
conditions, when the input supply (VPx or VH) dips transiently
below VDD, the synchronous rectifier switch immediately turns off
so that it does not pull VDD down. The VDD capacitor can then
act as a reservoir to keep the device active until the next highest
supply takes over the powering of the device. A 10 μF capacitor is
recommended for this reservoir/decoupling function.
The value of the VDDCAP capacitor may be increased if it is
necessary to guarantee a complete fault record is written into
EEPROM should all supplies fail. The value of the capacitor to
use is discussed in the Black Box Writes with No External
Supply section.
The VH input pin can accommodate supplies up to 14.4 V, which
allows the ADM1168 to be powered using a 12 V backplane supply.
In cases where this 12 V supply is hot swapped, it is recommended
that the ADM1168 not be connected directly to the supply. Suitable
precautions, such as the use of a hot swap controller or RC filter
network, should be taken to protect the device from transients
that may cause damage during hot swap events.
When two or more supplies are within 100 mV of each other, the
supply that first takes control of VDD keeps control. For example, if
VP1 is connected to a 3.3 V supply, VDD powers up to approximately
3.1 V through VP1. If VP2 is then connected to another 3.3 V
supply, VP1 still powers the device, unless VP2 goes 100 mV
higher than VP1.
SUPPLY
COMPARATOR
IN
EN
OUT
4.75V
LDO
IN
EN
OUT
4.75V
LDO
IN
EN
OUT
4.75V
LDO
IN
EN
OUT
4.75V
LDO
VH
VP3
VP2
VP1
V
DDCAP
INTERNAL
DEVICE
SUPPLY
09474-022
Figure 14. VDD Arbitrator Operation
ADM1168
Rev. 0 | Page 11 of 28
INPUTS
SUPPLY SUPERVISION
The ADM1168 has eight programmable inputs. Four of these
are dedicated supply fault detectors (SFDs). These dedicated
inputs are called VH and VPx (VP1 to VP3) by default. The
other four inputs are labeled VXx (VX1 to VX4) and have dual
functionality. They can be used either as SFDs, with functionality
similar to the VH and VPx, or as CMOS-/TTL-compatible logic
inputs to the device. Therefore, the ADM1168 can have up to
eight analog inputs, a minimum of four analog inputs and four
digital inputs, or a combination thereof. If an input is used as
an analog input, it cannot be used as a digital input. Therefore, a
configuration requiring eight analog inputs has no available
digital inputs. Table 6 shows the details of each input.
PROGRAMMING THE SUPPLY FAULT DETECTORS
The ADM1168 can have up to eight SFDs on its eight input
channels. These highly programmable reset generators enable
the supervision of up to eight supply voltages. The supplies can
be as low as 0.573 V and as high as 14.4 V. The inputs can be
configured to detect an undervoltage fault (the input voltage
drops below a preprogrammed value), an overvoltage fault (the
input voltage rises above a preprogrammed value), or an out-of-
window fault (the input voltage is outside a preprogrammed
range). The thresholds can be programmed to an 8-bit resolution
in registers provided in the ADM1168. This translates to a
voltage resolution that is dependent on the range selected.
The resolution is given by
Step Size = Threshold Range/255
Therefore, if the high range is selected on VH, the step size can
be calculated as follows:
(14.4 V − 6.0 V)/255 = 32.9 mV
Table 5 lists the upper and lower limits of each available range,
the bottom of each range (VB), and the range itself (VR).
Table 5. Voltage Range Limits
Voltage Range (V) VB (V) VR (V)
0.573 to 1.375 0.573 0.802
1.25 to 3.00 1.25 1.75
2.5 to 6.0 2.5 3.5
6.0 to 14.4 6.0 8.4
The threshold value required is given by
VT = (VR × N)/255 + VB
where:
VT is the desired threshold voltage (undervoltage or overvoltage).
VR is the voltage range.
N is the decimal value of the 8-bit code.
VB is the bottom of the range.
Reversing the equation, the code for a desired threshold is given by
N = 255 × (VT − VB)/VR
For example, if the user wants to set a 5 V overvoltage threshold
on VP1, the code to be programmed in the PS1OVTH register
(as described in the AN-721 Application Note) is given by
N = 255 × (5 − 2.5)/3.5
Therefore, N = 182 (1011 0110 or 0xB6).
ADM1168
Rev. 0 | Page 12 of 28
INPUT COMPARATOR HYSTERESIS
The UV and OV comparators shown in Figure 16 are always
monitoring VPx. To avoid chatter (multiple transitions when the
input is very close to the set threshold level), these comparators
have digitally programmable hysteresis. The hysteresis can be
programmed up to the values shown in Table 6 .
The hysteresis is added after a supply voltage goes out of
tolerance. Therefore, the user can program the amount above
the undervoltage threshold to which the input must rise before
an undervoltage fault is deasserted. Similarly, the user can program
the amount below the overvoltage threshold to which an input
must fall before an overvoltage fault is deasserted.
The hysteresis value is given by
VHYST = VR × NTHRESH/255
where:
VHYST is the desired hysteresis voltage.
NTHRESH is the decimal value of the 5-bit hysteresis code.
Note that NTHRESH has a maximum value of 31. The maximum
hysteresis for the ranges is listed in Table 6.
INPUT GLITCH FILTERING
The final stage of the SFDs is a glitch filter. This block provides
time-domain filtering on the output of the SFD comparators,
which allows the user to remove any spurious transitions such
as supply bounce at turn-on. The glitch filter function is in addition
to the digitally programmable hysteresis of the SFD comparators.
The glitch filter timeout is programmable up to 100 μs.
For example, when the glitch filter timeout is 100 μs, any pulse
appearing on the input of the glitch filter block that is less than
100 μs in duration is prevented from appearing on the output of
the glitch filter block. Any input pulse that is longer than 100 μs
appears on the output of the glitch filter block. The output is
delayed with respect to the input by 100 μs. The filtering process is
shown in Figure 15.
t
0
t
GF
t
0
t
GF
t
0
t
GF
t
0
t
GF
INPUT
INPUT PULSE SHORTE
R
THAN GLITCH FILTER TIMEOUT
INPUT PULSE LONGE
R
THAN GLITCH FILTER TIMEOUT
OUTPUT
PROGRAMMED
TIMEOUT
PROGRAMMED
TIMEOUT
INPUT
OUTPUT
09474-024
Figure 15. Input Glitch Filter Function
+
–
+
–
UV
COMPARATOR
VREF
FAULT TYPE
SELECT
OV
COMPARATOR
FAULT
OUTPUT
GLITCH
FILTER
VPx
MID
LOW
RANGE
SELECT
ULTRA
LOW
09474-023
Figure 16. Supply Fault Detector Block
Table 6. Input Functions, Thresholds, and Ranges
Input Function Voltage Range (V) Maximum Hysteresis Voltage Resolution (mV) Glitch Filter (μs)
VH High voltage analog input 2.5 to 6.0 425 mV 13.7 0 to 100
6.0 to 14.4 1.02 V 32.9 0 to 100
VPx Positive analog input 0.573 to 1.375 97.5 mV 3.14 0 to 100
1.25 to 3.00 212 mV 6.8 0 to 100
2.5 to 6.0 425 mV 13.7 0 to 100
VXx High-Z analog input 0.573 to 1.375 97.5 mV 3.14 0 to 100
Digital input 0 to 5.0 Not applicable Not applicable 0 to 100
ADM1168
Rev. 0 | Page 13 of 28
SUPPLY SUPERVISION WITH VXx INPUTS
The VXx inputs have two functions. They can be used as either
supply fault detectors or as digital logic inputs. When selected as
analog (SFD) inputs, the VXx pins have functionality that is very
similar to the VH and VPx pins. The primary difference is that the
VXx pins have only one input range: 0.573 V to 1.375 V. Therefore,
these inputs can directly supervise only the very low supplies.
However, the input impedance of the VXx pins is high, allowing
an external resistor divide network to be connected to the pin.
Thus, potentially any supply can be divided down into the input
range of the VXx pin and supervised. This enables the ADM1168
to monitor other supplies, such as +24 V, +48 V, and −5 V.
An additional supply supervision function is available when the
VXx pins are selected as digital inputs. In this case, the analog
function is available as a second detector on each of the dedicated
analog inputs, VPx and VH. The analog function of VX1 is mapped
to VP1, VX2 is mapped to VP2, and so on. VX4 is mapped to
VH. In this case, these SFDs can be viewed as secondary or
warning SFDs.
The secondary SFDs are fixed to the same input range as the
primary SFDs. They are used to indicate warning levels rather
than failure levels. This allows faults and warnings to be generated
on a single supply using only one pin. For example, if VP1 is set
to output a fault when a 3.3 V supply drops to 3.0 V, VX1 can be
set to output a warning at 3.1 V. Warning outputs are available
for readback from the status registers. They are also OR’ed together
and fed into the SE, allowing warnings to generate interrupts on
the PDOs. Therefore, in this example, if the supply drops to 3.1 V, a
warning is generated, and remedial action can be taken before
the supply drops out of tolerance.
VXx PINS AS DIGITAL INPUTS
As described in the Supply Supervision with VXX Inputs section,
the VXx input pins on the ADM1168 have dual functionality.
The second function is as a digital logic input to the device.
Therefore, the ADM1168 can be configured for up to four digital
inputs. These inputs are TTL-/CMOS-compatible inputs. Standard
logic signals can be applied to the pins: RESET from reset generators,
PWRGD signals, fault flags, manual resets, and more. These
signals are available as inputs to the SE and, therefore, can be used
to control the status of the PDOs. The inputs can be configured
to detect either a change in level or an edge.
When configured for level detection, the output of the digital
block is a buffered version of the input. When configured for
edge detection, a pulse of programmable width is output from
the digital block, when the logic transition is detected. The
width is programmable from 0 μs to 100 μs.
The digital blocks feature the same glitch filter function that is
available on the SFDs. This function enables the user to ignore
spurious transitions on the inputs. For example, the filter can be
used to debounce a manual reset switch.
When configured as digital inputs, each VXx pin has a weak
(10 μA) pull-down current source available for placing the input
into a known condition, even if left floating. The current source,
if selected, weakly pulls the input to GND.
DETECTOR
VXx
(DIGITAL INPUT)
GLITCH
FILTER
DIGITIAL THRESHOLD = 1.4V
TO
SEQUENCING
ENGINE
+
–
09474-027
Figure 17. VXx Digital Input Function
ADM1168
Rev. 0 | Page 14 of 28
OUTPUTS
SUPPLY SEQUENCING THROUGH
CONFIGURABLE OUTPUT DRIVERS
Supply sequencing is achieved with the ADM1168 using the
programmable driver outputs (PDOs) on the device as control
signals for supplies. The output drivers can be used as logic
enables or as FET drivers.
The sequence in which the PDOs are asserted (and, therefore,
the supplies are turned on) is controlled by the sequencing
engine (SE). The SE determines what action is taken with the
PDOs, based on the condition of the ADM1168 inputs. Therefore,
the PDOs can be set up to assert when the SFDs are in tolerance,
the correct input signals are received on the VXx digital pins,
and no warnings are received from any of the inputs of the device.
The PDOs can be used for a variety of functions. The primary
function is to provide enable signals for LDOs or dc-to-dc
converters that generate supplies locally on a board. The PDOs
can also be used to provide a PWRGD signal when all the SFDs
are in tolerance or a RESET output if one of the SFDs goes out
of specification (this can be used as a status signal for a DSP, FPGA,
or other microcontroller).
The PDOs can be programmed to pull up to a number of different
options. The outputs can be programmed as follows:
• Open drain (allowing the user to connect an external pull-up
resistor)
• Open drain with weak pull-up to VDD
• Open drain with strong pull-up to VDD
• Open drain with weak pull-up to VPx
• Open drain with strong pull-up to VPx
• Strong pull-down to GND
• Internally charge-pumped high drive (12 V, PDO1 to
PDO6 only)
The last option (available only on PDO1 to PDO6) allows the
user to directly drive a voltage high enough to fully enhance an
external NFET, which is used to isolate, for example, a card-side
voltage from a backplane supply (a PDO can sustain greater
than 10.5 V into a 1 μA load). The pull-down switches can also
be used to drive status LEDs directly.
The data driving each of the PDOs can come from one of three
sources. The source can be enabled in the PDOxCFG configuration
register (see the AN-721 Application Note for details).
The data sources are as follows:
• Output from the SE.
• Directly from the SMBus. A PDO can be configured so the
SMBus has direct control over it. This enables software
control of the PDOs. Therefore, a microcontroller can be
used to initiate a software power-up/power-down sequence.
• On-chip clock. A 100 kHz clock is generated on the device.
This clock can be made available on any of the PDOs. It
can be used, for example, to clock an external device such
as an LED.
DEFAULT OUTPUT CONFIGURATION
All of the internal registers in an unprogrammed ADM1168
device from the factory are set to 0. Because of this, the PDOx pins
are pulled to GND by a weak (20 kΩ), on-chip, pull-down resistor.
As the input supply to the ADM1168 ramps up on VPx or VH,
all PDOx pins behave as follows:
• Input supply = 0 V to 1.2 V. PDOs high impedance.
• Input supply = 1.2 V to 2.7 V. PDOs pulled to GND by a
weak (20 kΩ), on-chip, pull-down resistor.
• Supply > 2.7 V. Factory programmed devices continue to pull
all PDOs to GND by a weak (20 kΩ), on-chip, pull-down
resistor. Programmed devices download current EEPROM
configuration data, and the programmed setup is latched. The
PDO then goes to the state demanded by the configuration,
providing a known condition for the PDOs during power-up.
The internal pull-down can be overdriven with an external pull-up
of suitable value tied from the PDOx pin to the required pull-up
voltage. The 20 kΩ resistor must be accounted for in calculating
a suitable value. For example, if PDOx must be pulled up to 3.3 V,
and 5 V is available as an external supply, the pull-up resistor
value is given by
3.3 V = 5 V × 20 kΩ/(RUP + 20 kΩ)
Therefore,
RUP = (100 kΩ − 66 kΩ)/3.3 V = 10 kΩ
PDO
SE DATA
CFG4 CFG5 CFG6
SMBus DATA
CLK DATA
10Ω
20kΩ
10Ω
20kΩ
VP1
SEL
VP4
10Ω
20kΩ
V
DD
V
FET (PDO1 TO PDO6 ONLY)
20kΩ
09474-028
Figure 18. Programmable Driver Output
ADM1168
Rev. 0 | Page 15 of 28
SEQUENCING ENGINE
OVERVIEW
The ADM1168 SE provides the user with powerful and flexible
control of sequencing. The SE implements a state machine control
of the PDO outputs with state changes conditional on input
events. SE programs can enable complex control of boards such
as power-up and power-down sequence control, fault event
handling, and interrupt generation on warnings. A watchdog
function that verifies the continued operation of a processor
clock can be integrated into the SE program. The SE can also be
controlled via the SMBus, giving software or firmware control
of the board sequencing.
The SE state machine comprises 63 state cells. Each state has the
following attributes:
• It monitors signals indicating the status of the eight input
pins, VP1 to VP3, VH, and VX1 to VX4.
• It can be entered from any other state.
• Three exit routes move the state machine onto a next state:
sequence detection, fault monitoring, and timeout.
• Delay timers for the sequence and timeout blocks can be
programmed independently and changed with each state
change. The range of timeouts is from 0 ms to 400 ms.
• The output condition of the eight PDO pins is defined and
fixed within a state.
• It can transition from one state to the next in less than
20 μs, which is the time needed to download a state
definition from EEPROM to the SE.
• It can trigger a write of the black box fault and status
registers into the black box section of EEPROM.
SEQUENCE
TIMEOUT
MONITOR
FAULT STATE
09474-029
Figure 19. State Cell
The ADM1168 offers up to 63 state definitions. The signals
monitored to indicate the status of the input pins are the
outputs of the SFDs.
WARNINGS
The SE also monitors warnings. These warnings can be generated
when the ADC readings violate their limit register value or
when the secondary voltage monitors on VPx and VH are
triggered. The warnings are OR’ed together and are available
as a single warning input to each of the three blocks that enable
exiting a state.
SMBus JUMP (UNCONDITIONAL JUMP)
The SE can be forced to advance to the next state unconditionally.
This enables the user to force the SE to advance. Examples of the
use of this feature include moving to a margining state or debugging
a sequence. The SMBus jump or go-to command can be seen as
another input to sequence and timeout blocks to provide an exit
from each state.
Table 7. Sample Sequence State Entries
State Sequence Timeout Monitor
IDLE1 If VX1 is low, go to State IDLE2.
IDLE2 If VP1 is okay, go to State EN3V3.
EN3V3 If VP2 is okay, go to State EN2V5. If VP2 is not okay after 10 ms,
go to State DIS3V3.
If VP1 is not okay, go to State IDLE1.
DIS3V3 If VX1 is high, go to State IDLE1.
EN2V5 If VP3 is okay, go to State PWRGD. If VP3 is not okay after 20 ms,
go to State DIS2V5.
If VP1 or VP2 is not okay, go to State FSEL2.
DIS2V5 If VX1 is high, go to State IDLE1.
FSEL1 If VP3 is not okay, go to State DIS2V5. If VP1 or VP2 is not okay, go to State FSEL2.
FSEL2 If VP2 is not okay, go to State DIS3V3. If VP1 is not okay, go to State IDLE1.
PWRGD If VX1 is high, go to State DIS2V5. If VP1, VP2, or VP3 is not okay, go to State FSEL1.
ADM1168
Rev. 0 | Page 16 of 28
SEQUENCING ENGINE APPLICATION EXAMPLE
The application in this section demonstrates the operation of
the SE. Figure 21 shows how the simple building block of a single
SE state can be used to build a power-up sequence for a three-
supply system. Table 8 lists the PDO outputs for each state in
the same SE implementation. In this system, a good 5 V supply
on the VP1 pin and the VX1 pin held low are the triggers required
to start a power-up sequence. The sequence next turns on the 3.3 V
supply, then the 2.5 V supply (assuming successful turn on of the
3.3 V supply). When all three supplies have turned on correctly,
the PWRGD state is entered, where the SE remains until a fault
occurs on one of the three supplies or until it is instructed to go
through a power-down sequence by VX1 going high.
Faults are dealt with throughout the power-up sequence on a
case-by-case basis. The following three sections (the Sequence
Detector section, the Monitoring Fault Detector section, and
the Timeout Detector section) describe the individual blocks
and use the sample application shown in Figure 21 to demonstrate
the actions of the state machine.
Sequence Detector
The sequence detector block is used to detect when a step in a
sequence has been completed. It looks for one of the SE inputs
to change state and is most often used as the gate for successful
progress through a power-up or power-down sequence. A timer
block that is included in this detector can insert delays into a
power-up or power-down sequence, if required. Timer delays
can be set from 10 μs to 400 ms. Figure 20 is a block diagram
of the sequence detector.
SUPPLY FAULT
DETECTION
LOGIC INPUT CHANGE
OR FAULT DETECTION
WARNINGS
FORCE FLOW
(UNCONDITIONAL JUMP)
VP1
VX4
INVERT
SEQUENCE
DETECTOR
SELECT
TIMER
09474-032
Figure 20. Sequence Detector Block Diagram
If a timer delay is specified, the input to the sequence detector
must remain in the defined state for the duration of the timer
delay. If the input changes state during the delay, the timer is reset.
The sequence detector can also help to identify monitoring faults.
In the sample application shown in Figure 21, the FSEL1 and
FSEL2 states first identify which of the VP1, VP2, or VP3 pins
has faulted, and then they take appropriate action.
IDLE1
IDLE2
EN3V3
DIS3V3
DIS2V5PWRGD
FSEL1
FSEL2
SEQUENCE
STATES
MONITOR FAULT
STATES
TIMEOUT
STATES
VX1 = 0
VP1 = 1
VP1 = 0
(VP1 + VP2) = 0
(VP1 + VP2 + VP3) = 0
(VP1 +
VP2) = 0
VP2 = 1
VP3 = 1
VP2 = 0
VX1 = 1
VP3 = 0
VP2 = 0
VP1 = 0
VX1 = 1
VX1 = 1
10ms
20ms
EN2V5
09474-030
Figure 21. Sample Application Flow Diagram
Table 8. PDO Outputs for Each State
PDO Outputs IDLE1 IDLE2 EN3V3 EN2V5 DIS3V3 DIS2V5 PWRGD FSEL1 FSEL2
PDO1 = 3V3ON 0 0 1 1 0 1 1 1 1
PDO2 = 2V5ON 0 0 0 1 1 0 1 1 1
PDO3 = FAULT 0 0 0 0 1 1 0 1 1
ADM1168
Rev. 0 | Page 17 of 28
Monitoring Fault Detector
The monitoring fault detector block is used to detect a failure on an
input. The logical function implementing this is a wide OR gate
that can detect when an input deviates from its expected condition.
The clearest demonstration of the use of this block is in the
PWRGD state, where the monitor block indicates that a failure
on one or more of the VPx, VXx, or VH inputs has occurred.
No programmable delay is available in this block because the
triggering of a fault condition is likely to be caused by a supply
falling out of tolerance. In this situation, the device needs to react as
quickly as possible. Some latency occurs when moving out of this
state, however, because it takes a finite amount of time (~20 μs) for
the state configuration to download from the EEPROM into the
SE. Figure 22 is a block diagram of the monitoring fault detector.
SUPPLY FAULT
DETECTION
LOGIC INPUT CHANGE
OR FAULT DETECTION
V
P1
V
X4
MONITORING FAULT
DETECTOR
MASK
SENSE
1-BIT FAULT
DETECTOR
FAULT
WARNINGS
MASK
1-BIT FAULT
DETECTOR
FAULT
MASK
SENSE
1-BIT FAULT
DETECTOR
FAULT
09474-033
Figure 22. Monitoring Fault Detector Block Diagram
Timeout Detector
The timeout detector allows the user to trap a failure to ensure
proper progress through a power-up or power-down sequence.
In the sample application shown in Figure 21, the timeout next-
state transition is from the EN3V3 and EN2V5 states. For the
EN3V3 state, the signal 3V3ON is asserted on the PDO1 output
pin upon entry to this state to turn on a 3.3 V supply.
This supply rail is connected to the VP2 pin, and the sequence
detector looks for the VP2 pin to go above its undervoltage
threshold, which is set in the supply fault detector (SFD) attached
to that pin.
The power-up sequence progresses when this change is detected. If,
however, the supply fails (perhaps due to a short circuit overloading
this supply), the timeout block traps the problem. In this example,
if the 3.3 V supply fails within 10 ms, the SE moves to the DIS3V3
state and turns off this supply by bringing PDO1 low. It also
indicates that a fault has occurred by taking PDO3 high. Timeout
delays of 100 μs to 400 ms can be programmed.
FAULT AND STATUS REPORTING
The ADM1168 has a fault latch for recording faults. Two registers,
FSTAT1 and FSTAT2, are set aside for this purpose. A single bit
is assigned to each input of the device, and a fault on that input
sets the relevant bit. The contents of the fault register can be
read out over the SMBus to determine which input(s) faulted.
The fault register can be enabled or disabled in each state. To
latch data from one state, ensure that the fault latch is disabled
in the following state. This ensures that only real faults are
captured and not, for example, undervoltage conditions that
may be present during a power-up or power-down sequence.
The ADM1168 also has a number of status registers. These include
more detailed information, such as whether an undervoltage or
overvoltage fault is present on a particular input. The status
registers also include information on ADC limit faults.
There are two sets of these registers with different behaviors.
The first set of status registers is not latched in any way and,
therefore, can change at any time in response to changes on the
inputs. These registers provide information such as the UV and
OV state of the inputs, the digital state of the GPI VXx inputs,
and the ADC warning limit status.
The second set of registers update each time the sequence engine
changes state and are latched until the next state change. The
second set of registers provides the same information as the first
set, but in a more compact form. The reason for this is that these
registers are used by the black box feature when writing status
information for the previous state into EEPROM.
See the AN-721 Application Note for full details about the
ADM1168 registers.
NONVOLATILE BLACK BOX FAULT RECORDING
A section of EEPROM, from Address 0xF900 to Address 0xF9FF, is
provided that by default can be used to store user-defined settings
and information. Part of this section of EEPROM, Address 0xF980
to Address 0xF9FF, can instead be used to store up to 16 fault records.
Any sequencing engine state can be designated as a black box write
state. Each time the sequence engine enters that state, a fault record
is written into EEPROM. The fault record provides a snapshot of
the entire ADM1168 state at the point in time when the last state
was exited, just prior to entering the designated black box write
state. A fault record contains the following information:
• A flag bit set to 0 after the fault record has been written.
• The state number of the previous state prior to the fault
record write state.
• Did a sequence, timeout, or monitor condition cause the
previous state to exit?
• UVSTATx and OVSTATx input comparator status.
• VXx GPISTAT status.
• LIMSTATx status.
• A checksum byte.
ADM1168
Rev. 0 | Page 18 of 28
Each fault record contains eight bytes, with each byte taking
typically about 250 μs to write to EEPROM, for a total write
time of about 2 ms. After the black box begins to write a fault
record into EEPROM, the ADM1168 ensures that it is complete
before attempting to write any additional fault records. This means
that if consecutive sequencing engine states are designated as
black box write states, then a time delay must be used in the first
state to ensure that the fault record is written before moving to
the next state.
When the ADM1168 powers on initially, it performs a search
to find the first fault record that has not been written to. It does
this by checking the flag bit in each fault record until it finds
one where the flag bit is 1. The first fault record is stored at
Address 0xF980, and at multiples of eight bytes after that, with
the last record stored at Address 0xF9F8.
The fault recorder is only able to write in the EEPROM. It is not able
to erase the EEPROM prior to writing the fault record. Therefore,
to ensure correct operation, it is important that the fault record
EEPROM is erased prior to use. When all the EEPROM locations
for the fault records are used, no more fault records are written.
This ensures that the first fault in any cascading fault is stored and
not overwritten and lost.
To avoid the fault recorder filling up and fault records being lost, an
application can periodically poll the ADM1168 to determine if there
are fault records to be read. Alternatively, one of the PDOx outputs
can be used to generate an interrupt for a processor in the fault
record write state to signal the need to come and read one or more
fault records.
After reading fault records during normal operation, two things
must be done before the fault recorder will be able to reuse the
EEPROM locations. First, the EEPROM section must be erased.
The fault recorder must then be reset so that it performs its search
again for the first unused location of EEPROM that is available to
store a fault record.
BLACK BOX WRITES WITH NO EXTERNAL SUPPLY
In cases where all the input supplies fail, for example, if the card
has been removed from a powered backplane, the state machine
can be programmed to trigger a write into the black box EEPROM.
The decoupling capacitors on the rail that power the ADM1168
and other loads on the board form an energy reservoir. Depending
on the other loads on the board and their behavior as the supply
rails drop, there may be sufficient energy in the decoupling
capacitors to allow the ADM1168 to write a complete fault record
(eight bytes of data).
Typically, it takes 2 ms to write to the eight bytes of a fault record. If
the ADM1168 is powered using a 12 V supply on the VH pin, then
a UV threshold at 6 V can be set and used as the state machine
trigger to start writing a fault record to EEPROM. The higher the
threshold is, the earlier the black box write begins, and the more
energy available in the decoupling capacitors to ensure it completes
successfully.
Provided the VH supply, or another supply connected to a VPx pin,
remains above 3.0 V during the time to write, the entire fault record
is always written to the EEPROM. In many cases, there should be
sufficient decoupling capacitors on a board to power the
ADM1168 as it writes into the EEPROM.
In cases where the decoupling capacitors are not able to supply
sufficient energy after the board is removed to ensure a complete
fault record is written, the value of the capacitor on VDDCAP
may be increased. In the worst case, assuming that no energy is
supplied to the ADM1168 by the external decoupling capacitors,
but that VDDCAP has 4.75 V on it, then a 47 μF is sufficient to
guarantee that a single complete black box record can be written
to the EEPROM.
ADM1168
Rev. 0 | Page 19 of 28
APPLICATIONS DIAGRAM
3.3V OUT
VH
PDO8
PDO7
SIGNAL VALID
PDO6
PDO2
PDO1
PDO5
PDO4
PDO3
EN OUT
DC-TO-DC1
IN
3.3V OUT
3V OUT
5V OUT
12V OUT
EN OUT
DC-TO-DC2
IN
1.25V OUT
EN OUT
DC-TO-DC3
IN
EN OUT
LDO
IN
1.25V OUT
0.9V OUT
12V IN
5V IN
3V IN
5V OUT VP1
3V OUT VP2
3.3V OUT VP3
1.25V OUT VX1
1.2V OUT VX2
0.9V OUT VX3
VX4
10µF
VCCP
10µF
REFOUT
10µF
VDDCAP GND
ADM1168
PWRGD
RESET
09474-068
Figure 23. Applications Diagram
ADM1168
Rev. 0 | Page 20 of 28
COMMUNICATING WITH THE ADM1168
CONFIGURATION DOWNLOAD AT POWER-UP
The configuration of the ADM1168 (undervoltage/overvoltage
thresholds, glitch filter timeouts, and PDO configurations) is
dictated by the contents of the RAM. The RAM comprises
digital latches that are local to each of the functions on the
device. The latches are double-buffered and have two identical
latches, Latch A and Latch B. Therefore, when an update to a
function occurs, the contents of Latch A are updated first, and
then the contents of Latch B are updated with identical data.
The advantages of this architecture are explained in detail in
the Updating the Configuration section.
The two latches are volatile memory and lose their contents at
power-down. Therefore, the configuration in the RAM must be
restored at power-up by downloading the contents of the EEPROM
(nonvolatile memory) to the local latches. This download occurs in
steps, as follows:
1. With no power applied to the device, the PDOs are all high
impedance.
2. When 1.2 V appears on any of the inputs connected to the
VDD arbitrator (VH or VPx), the PDOs are all weakly
pulled to GND with a 20 kΩ resistor.
3. When the supply rises above the undervoltage lockout of
the device (UVLO is 2.5 V), the EEPROM starts to
download to the RAM.
4. The EEPROM downloads its contents to all Latch As.
5. When the contents of the EEPROM are completely
downloaded to the Latch As, the device controller signals
all Latch As to download to all Latch Bs simultaneously,
completing the configuration download.
6. At 0.5 ms after the configuration download completes,
the first state definition is downloaded from EEPROM
into the SE.
Note that any attempt to communicate with the device prior to
the completion of the download causes the ADM1168 to issue
a no acknowledge (NACK).
UPDATING THE CONFIGURATION
After power-up, with all the configuration settings loaded from
the EEPROM into the RAM registers, the user may need to alter
the configuration of functions on the ADM1168, such as changing
the undervoltage or overvoltage limit of an SFD, changing the
fault output of an SFD, or adjusting the rise time delay of one
of the PDOs.
The ADM1168 provides several options that allow the user to
update the configuration over the SMBus interface. The following
three options are controlled in the UPDCFG register.
Option 1
Update the configuration in real time. The user writes to
the RAM across the SMBus, and the configuration is updated
immediately.
Option 2
Update the Latch As without updating the Latch Bs. With this
method, the configuration of the ADM1168 remains unchanged
and continues to operate in the original setup until the instruction
is given to update the Latch Bs.
Option 3
Change the EEPROM register contents without changing the
RAM contents, and then download the revised EEPROM contents
to the RAM registers. With this method, the configuration of the
ADM1168 remains unchanged and continues to operate in the
original setup until the instruction is given to update the RAM.
The instruction to download from the EEPROM in the Option 3
section is also a useful way to restore the original EEPROM
contents if revisions to the configuration are unsatisfactory. For
example, if the user needs to alter an overvoltage threshold, the
RAM register can be updated, as described in the Option 1
section. However, if the user is not satisfied with the change and
wants to revert to the original programmed value, the device
controller can issue a command to download the EEPROM
contents to the RAM again, as described in the Option 3
section, restoring the ADM1168 to its original configuration.
The topology of the ADM1168 makes this type of operation
possible. The local, volatile registers (RAM) are all double-
buffered latches. Setting Bit 0 of the UPDCFG register to leaves the
double buffered latches open at all times, allowing the registers
to be updated continuously as they are written to. If Bit 0 is set
to 0 when a RAM write occurs across the SMBus, only the first
side of the double-buffered latch is written to. The user must
then write a 1 to Bit 1 of the UPDCFG register. This generates a
pulse to update all the second latches at once. EEPROM writes
occur in a similar way.
The final bit in this register can enable or disable EEPROM page
erasure. If this bit is set high, the contents of an EEPROM page
can all be set to 1. If this bit is set low, the contents of a page
cannot be erased, even if the command code for page erasure is
programmed across the SMBus. The bit map for the UPDCFG
register is shown in the AN-721 Application Note. A flow diagram
for download at power-up and subsequent configuration updates is
shown in Figure 24.
ADM1168
Rev. 0 | Page 21 of 28
POWER-UP
(V
CC
> 2.5V)
EEPROM
E
E
P
R
O
M
L
D
D
A
T
A
R
A
M
L
D
U
P
D
SMBus
DEVICE
CONTROLLER
LATCH A LATCH B FUNCTION
(OV THRESHOLD
ON VP1)
09474-035
Figure 24. Configuration Update Flow Diagram
UPDATING THE SEQUENCING ENGINE
SE functions are not updated in the same way as regular
configuration latches. The SE has its own dedicated 512-byte
EEPROM for storing state definitions, providing 63 individual
states, each with a 64-bit word (one state is reserved). At power-up,
the first state is loaded from the SE EEPROM into the engine
itself. When the conditions of this state are met, the next state is
loaded from the EEPROM into the engine and so on. The loading
of each new state takes approximately 10 μs.
To alter a state, the required changes must be made directly to
the EEPROM. RAM for each state does not exist. The relevant
alterations must be made to the 64-bit word, which is then
uploaded directly to the EEPROM.
INTERNAL REGISTERS
The ADM1168 contains a large number of data registers. The
principal registers are the address pointer register and the
configuration registers.
Address Pointer Register
The address pointer register contains the address that selects one
of the other internal registers. When writing to the ADM1168, the
first byte of data is always a register address that is written to the
address pointer register.
Configuration Registers
The configuration registers provide control and configuration
for various operating parameters of the ADM1168. See the
AN-721 Application Note.
EEPROM
The ADM1168 has two 512-byte cells of nonvolatile, electrically
erasable, programmable, read-only memory (EEPROM), from
Address 0xF800 to Register Address 0xFBFF. The EEPROM is
used for permanent storage of data that is not lost when the
ADM1168 is powered down. One EEPROM cell, 0xF800 to
0xF9FF, contains the configuration data, user information and,
if enabled, any fault records of the device; the other section, 0xFA00
to 0xFBFF, contains the state definitions for the SE. Although
referred to as read-only memory, the EEPROM can be written to,
as well as read from, using the serial bus in exactly the same way
as the other registers.
The major differences between the EEPROM and other registers
are as follows:
• An EEPROM location must be blank before it can be
written to. If it contains data, the data must first be erased.
• Writing to the EEPROM is slower than writing to the RAM.
• Writing to the EEPROM should be restricted because it has
a limited write/cycle life of typically 10,000 write operations
due to the usual EEPROM wear-out mechanisms.
The first EEPROM is split into 16 (0 to 15) pages of 32 bytes each.
Page 0 to Page 4, from Address 0xF800 to Address 0xF89F, hold
the configuration data for the applications on the ADM1168
(such as the SFDs and PDOs). These EEPROM addresses are
the same as the RAM register addresses, prefixed by F8. Page 5
to Page 7, from Address 0xF8A0 to Address 0xF8FF, are reserved.
Page 8 to Page 11 are available for customer use to store any
information that may be required by the customer in their
application. Customers can store information on Page 12 to
Page 15, or these pages can store the fault records written by
the sequencing engine if users have decided to enable writing
of the fault records for different states.
Data can be downloaded from the EEPROM to the RAM in one
of the following ways:
• At power-up, when Page 0 to Page 4 are downloaded.
• By setting Bit 0 of the UDOWNLD register (0xD8), which
performs a user download of Page 0 to Page 4.
When the sequence engine is enabled, it is not possible to access
the section of EEPROM from Address 0xFA00 to Address 0xFBFF.
The sequence engine must be halted before it is possible to read
or write to this range. Attempting to read or write to this range if
the sequence engine is not halted generates a no acknowledge,
or NACK.
Read/write access to the configuration and user EEPROM ranges
from Address 0xF800 to Address 0xF89F and Address 0xF900 to
Address 0xF9FF depends on whether the black box fault recorder
is enabled. If the fault recorder is enabled and one or more states
have been set as fault record trigger states, then it is not possible
to access any EEPROM location in this range without first halting
the black box. Attempts to read or write to this EEPROM range
while the fault recorder is operating are acknowledged by the
device but do not return any useful data or modify the EEPROM in
any way.
ADM1168
Rev. 0 | Page 22 of 28
If none of the states are set as fault record trigger states, then the
black box is considered disabled, and read/write access is allowed
without having to halt the black box fault recorder.
SERIAL BUS INTERFACE
The ADM1168 is controlled via the serial system management
bus (SMBus) and is connected to this bus as a slave device under
the control of a master device. It takes approximately 1 ms after
power-up for the ADM1168 to download from its EEPROM.
Therefore, access to the ADM1168 is restricted until the download
is complete.
Identifying the ADM1168 on the SMBus
The ADM1168 has a 7-bit serial bus slave address (see Tabl e 9 ).
The device is powered up with a default serial bus address. The
five MSBs of the address are set to 10001; the two LSBs are
determined by the logical states of Pin A1 and Pin A0. This
allows the connection of four ADM1168s to one SMBus.
Table 9. Serial Bus Slave Address
A1 Pin A0 Pin Hex Address 7-Bit Address1
Low Low 0x88 1000100x
Low High 0x8A 1000101x
High Low 0x8C 1000110x
High High 0x8E 1000111x
1 x = read/write bit. The address is shown only as the first 7 MSBs.
The device also has several identification registers (read-only)
that can be read across the SMBus. Table 1 0 lists these registers
with their values and functions.
Table 10. Identification Register Values and Functions
Name Address Value Function
MANID 0xF4 0x41 Manufacturer ID for Analog Devices
REVID 0xF5 0x02 Silicon revision
MARK1 0xF6 0x00 Software brand
MARK2 0xF7 0x00 Software brand
General SMBus Timing
Figure 25, Figure 26, and Figure 27 are timing diagrams for general
read and write operations using the SMBus. The SMBus specification
defines specific conditions for different types of read and write
operations, which are discussed in the Write Operations and
Read Operations sections.
The general SMBus protocol operates in the following three steps.
Step 1
The master initiates data transfer by establishing a start condition,
defined as a high-to-low transition on the serial data line SDA,
while the serial clock line SCL remains high. This indicates that
a data stream follows. All slave peripherals connected to the serial
bus respond to the start condition and shift in the next eight bits,
consisting of a 7-bit slave address (MSB first) plus an 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 (0 = write,
1 = read).
The peripheral whose address corresponds to the transmitted
address responds by pulling the data line low during the low
period before the ninth clock pulse, known as the acknowledge
bit, and by holding it low during the high period of this clock pulse.
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 a 0,
the master writes to the slave device. If the R/W bit is a 1, the
master reads from the slave device.
Step 2
Data is sent over the serial bus in sequences of nine clock pulses,
eight bits of data followed by an acknowledge bit from the slave
device. Data transitions on the data line must occur during the
low period of the clock signal and remain stable during the high
period because a low-to-high transition when the clock is high
may be interpreted as a stop signal. If the operation is a write
operation, the first data byte after the slave address is a command
byte. This command byte tells the slave device what to expect next.
It may be an instruction telling the slave device to expect a block
write, or it may be a register address that tells the slave where
subsequent data is to be written. Because data can flow in only
one direction, as defined by the R/W bit, sending a command to
a slave device during a read operation is not possible. Before a read
operation, it may be necessary to perform a write operation to
tell the slave what sort of read operation to expect and the address
from which data is to be read.
Step 3
When all data bytes have been read or written, stop conditions
are established. In write mode, the master pulls the data line high
during the 10th clock pulse to assert a stop condition. In read
mode, the master device releases the SDA line during the low
period before the ninth clock pulse, but the slave device does not
pull it low. This is known as a no acknowledge. The master then
takes the data line low during the low period before the 10th clock
pulse and then high during the 10th clock pulse to assert a stop
condition.
ADM1168
Rev. 0 | Page 23 of 28
9
19 91
191
START BY
MASTER
ACK. BY
SLAVE
ACK. BY
SLAVE
ACK. BY
SLAVE
ACK. BY
SLAVE
FRAME 2
COMMAND CODE
FRAME 1
SLAVE ADDRESS
FRAME N
DATA BYTE
FRAME 3
DATA BYTE
SCL
SDA R/W
STOP
BY
MASTER
SCL
(CONTINUED)
SDA
(CONTINUED)
D7A0A11001 0 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
09474-036
Figure 25. General SMBus Write Timing Diagram
19 91
1919
START BY
MASTER
ACK. BY
SLAVE
ACK. BY
MASTER
ACK. BY
MASTER NO ACK.
FRAME 2
DATA BYTE
FRAME 1
SLAVE ADDRESS
FRAME N
DATA BYTE
FRAME 3
DATA BYTE
SCL
SDA R/W
STOP
BY
MASTER
SCL
(CONTINUED)
SDA
(CONTINUED)
D7A0A11001 0 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
09474-037
Figure 26. General SMBus Read Timing Diagram
SCL
SDA
PS S P
t
SU;STO
t
HD;STA
t
SU;STA
t
SU;DAT
t
HD;DAT
t
HD;STA
t
HIGH
t
BUF
t
LOW
t
R
t
F
09474-038
Figure 27. Serial Bus Timing Diagram
ADM1168
Rev. 0 | Page 24 of 28
SMBus PROTOCOLS FOR RAM AND EEPROM
The ADM1168 contains volatile registers (RAM) and nonvolatile
registers (EEPROM). User RAM occupies Address 0x00 to
Address 0xDF; and the EEPROM occupies Address 0xF800
to Address 0xFBFF.
Data can be written to and read from both the RAM and the
EEPROM as single data bytes. Data can be written only to
unprogrammed EEPROM locations. To write new data to a
programmed location, the location contents must first be erased.
EEPROM erasure cannot be done at the byte level. The EEPROM
is arranged as 32 pages of 32 bytes each, and an entire page
must be erased.
Page erasure is enabled by setting Bit 2 in the UPDCFG register
(Address 0x90) to 1. If this bit is not set, page erasure cannot
occur, even if the command byte (0xFE) is programmed across
the SMBus.
WRITE OPERATIONS
The SMBus specification defines several protocols for different
types of read and write operations. The following abbreviations
are used in Figure 28 to Figure 36:
• S = Start
• P = Stop
• R = Read
• W = Write
• A = Acknowledge
• A = No acknowledge
The ADM1168 uses the following SMBus write protocols.
Send Byte
In a send byte operation, the master device sends a single
command byte to a slave device, as follows:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts an acknowledge (ACK)
on SDA.
4. The master sends a command code.
5. The slave asserts ACK on SDA.
6. The master asserts a stop condition on SDA and the
transaction ends.
In the ADM1168, the send byte protocol is used for two
purposes:
• To write a register address to the RAM for a subsequent
single byte read from the same address, or for a block read or
a block write starting at that address, as shown in Figure 28.
2413 5
SLAVE
ADDRESS
RAM
ADDRESS
(0x00 TO 0xDF)
SWA A
6
P
09474-039
Figure 28. Setting a RAM Address for Subsequent Read
• To erase a page of EEPROM memory. EEPROM memory
can be written to only if it is unprogrammed. Before writing
to one or more EEPROM memory locations that are already
programmed, the page(s) containing those locations must
first be erased. EEPROM memory is erased by writing a
command byte.
The master sends a command code telling the slave device
to erase the page. The ADM1168 command code for a page
erasure is 0xFE (1111 1110). Note that for a page erasure to
take place, the page address must be given in the previous
write word transaction (see the Write Byte/Word section).
In addition, Bit 2 in the UPDCFG register (Address 0x90)
must be set to 1. See Figure 29.
2413 5
SLAVE
ADDRESS
COMMAND
BYTE
(0xFE)
SWA A
6
P
09474-040
Figure 29. EEPROM Page Erasure
As soon as the ADM1168 receives the command byte,
page erasure begins. The master device can send a stop
command as soon as it sends the command byte. Page
erasure takes approximately 20 ms. If the ADM1168 is
accessed before erasure is complete, it responds with a
no acknowledge (NACK).
Write Byte/Word
In a write byte/word operation, the master device sends a
command byte and one or two data bytes to the slave device,
as follows:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts ACK on SDA.
4. The master sends a command code.
5. The slave asserts ACK on SDA.
6. The master sends a data byte.
7. The slave asserts ACK on SDA.
8. The master sends a data byte or asserts a stop condition.
9. The slave asserts ACK on SDA.
10. The master asserts a stop condition on SDA to end the
transaction.
In the ADM1168, the write byte/word protocol is used for three
purposes:
• To write a single byte of data to the RAM. In this case, the
command byte is RAM Address 0x00 to RAM Address 0xDF,
and the only data byte is the actual data, as shown in Figure 30.
SLAVE
ADDRESS
RAM
ADDRESS
(0x00 TO 0xDF)
S W A DATAAPA
2413 576 8
09474-041
Figure 30. Single Byte Write to the RAM
ADM1168
Rev. 0 | Page 25 of 28
8
• To set up a 2-byte EEPROM address for a subsequent read,
write, block read, block write, or page erase. In this case, the
command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The only data byte is the low
byte of the EEPROM address, as shown in Figure 31.
Unlike some EEPROM devices that limit block writes to within
a page boundary, there is no limitation on the start address when
performing a block write to EEPROM, except when
• There must be at least N locations from the start address to
the highest EEPROM address (0xFBFF) to avoid writing to
invalid addresses.
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 76
09474-042
• An address crosses a page boundary. In this case, both
pages must be erased before programming.
Figure 31. Setting an EEPROM Address Note that the ADM1168 features a clock extend function for
writes to the EEPROM. Programming an EEPROM byte takes
approximately 250 μs, which limits the SMBus clock for repeated
or block write operations. The ADM1168 pulls SCL low and
extends the clock pulse when it cannot accept any more data.
Because a page consists of 32 bytes, only the three MSBs of
the address low byte are important for page erasure. The
lower five bits of the EEPROM address low byte specify the
addresses within a page and are ignored during an erase
operation. READ OPERATIONS
• To write a single byte of data to the EEPROM. In this case, the
command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The first data byte is the low
byte of the EEPROM address, and the second data byte is
the actual data, as shown in Figure 32.
The ADM1168 uses the following SMBus read protocols.
Receive Byte
In a receive byte operation, the master device receives a single
byte from a slave device, as follows:
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
AA
2413 5 7
A
9
DATA
86
P
10
09474-043
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
read bit (high).
3. The addressed slave device asserts ACK on SDA.
Figure 32. Single Byte Write to the EEPROM
4. The master receives a data byte.
Block Write 5. The master asserts NACK on SDA.
In a block write operation, the master device writes a block of
data to a slave device, as shown in Figure 34. The start address
for a block write must have been set previously. In the ADM1168,
a send byte operation sets a RAM address, and a write byte/word
operation sets an EEPROM address as follows:
6. The master asserts a stop condition on SDA, and the
transaction ends.
In the ADM1168, the receive byte protocol is used to read a
single byte of data from a RAM or EEPROM location whose
address has previously been set by a send byte or write byte/
word operation, as shown in Figure 33.
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by
the write bit (low).
23145
SLAVE
ADDRESS
SRDATAA
6
P
A
09474-045
3. The addressed slave device asserts ACK on SDA.
4. The master sends a command code that tells the slave
device to expect a block write. The ADM1168 command
code for a block write is 0xFC (1111 1100).
Figure 33. Single Byte Read from the EEPROM or RAM
5. The slave asserts ACK on SDA.
6. The master sends a data byte that tells the slave device how
many data bytes are being sent. The SMBus specification
allows a maximum of 32 data bytes in a block write.
7. The slave asserts ACK on SDA.
8. The master sends N data bytes.
9. The slave asserts ACK on SDA after each data byte.
10. The master asserts a stop condition on SDA to end the
transaction.
SLAVE
ADDRESS
SWA
2
COMMAND 0xFC
(BLOCK WRITE)
413
A
5
BYTE
COUNT
6
A
7
A
910
A PA
DATA
1
8
DATA
N
DATA
2
09474-044
Figure 34. Block Write to the EEPROM or RAM
ADM1168
Rev. 0 | Page 26 of 28
Block Read
In a block read operation, the master device reads a block of data
from a slave device. The start address for a block read must have
been set previously. In the ADM1168, this is done by a send byte
operation to set a RAM address, or a write byte/word operation to
set an EEPROM address. The block read operation itself consists of
a send byte operation that sends a block read command to the
slave, immediately followed by a repeated start and a read operation
that reads out multiple data bytes, as follows:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts ACK on SDA.
4. The master sends a command code that tells the slave
device to expect a block read. The ADM1168 command
code for a block read is 0xFD (1111 1101).
5. The slave asserts ACK on SDA.
6. The master asserts a repeat start condition on SDA.
7. The master sends the 7-bit slave address followed by the
read bit (high).
8. The slave asserts ACK on SDA.
9. The ADM1168 sends a byte-count data byte that tells the
master how many data bytes to expect. The ADM1168
always returns 32 data bytes (0x20), which is the maximum
allowed by the SMBus 1.1 specification.
10. The master asserts ACK on SDA.
11. The master receives 32 data bytes.
12. The master asserts ACK on SDA after each data byte.
13. The master asserts a stop condition on SDA to end the
transaction. See Figure 35.
Error Correction
The ADM1168 provides the option of issuing a packet error
checking (PEC) byte after a write to the RAM, a write to the
EEPROM, a block write to the RAM/EEPROM, or a block read
from the RAM/EEPROM. This option enables the user to verify
that the data received by or sent from the ADM1168 is correct.
The PEC byte is an optional byte sent after that last data byte has
been written to or read from the ADM1168. The protocol is the
same as a block read for Step 1 to Step 12 and then proceeds as
follows:
13. The ADM1168 issues a PEC byte to the master. The master
checks the PEC byte and issues another block read, if the
PEC byte is incorrect.
14. A no acknowledge (NACK) is generated after the PEC byte
to signal the end of the read.
15. The master asserts a stop condition on SDA to end the
transaction.
Note that the PEC byte is calculated using CRC-8. The frame
check sequence (FCS) conforms to CRC-8 by the polynomial
C(x) = x8 + x2 + x1 + 1
See the SMBus 1.1 specification for details.
An example of a block read with the optional PEC byte is shown
in Figure 36.
SLAVE
ADDRESS
SWA
2
COMMAND 0xFD
(BLOCK READ)
413
A
5
S
6
SLAVE
ADDRESS
7
BYTE
COUNT
910 1211
ARA
8
DATA
1
DATA
32 A
13
P
A
09474-046
Figure 35. Block Read from the EEPROM or RAM
SLAVE
ADDRESS
SWA
2
COMMAND 0xFD
(BLOCK READ)
413
A
5
S
6
SLAVE
ADDRESS
7
BYTE
COUNT
910 1211
ARA
8
DATA
1
DATA
32 A
13
PEC
14
A
15
P
A
09474-047
Figure 36. Block Read from the EEPROM or RAM with PEC
ADM1168
Rev. 0 | Page 27 of 28
OUTLINE DIMENSIONS
COMPLIANT TO JEDEC STANDARDS MS-026-BBA
VIEW A
TOP VIEW
(PINS DOWN)
8
1
32 25
24
17
16
9
0.80
BSC
LEAD PITCH
9.00
BSC SQ
7.00
BSC SQ
1.60
MAX
0.75
0.60
0.45
0.45
0.37
0.30
PIN 1
0.20
0.09
1.45
1.40
1.35
0.10 MAX
COPLANARITY
VIEW A
ROTATED 90° CCW
SEATING
PLANE
7°
3.5°
0°
0.15
0.05
Figure 37. 32-Lead Low Profile Quad Flat Package [LQFP]
(ST-32-2)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
ADM1168ASTZ −40°C to +85°C 32-Lead Low Profile Quad Flat Package [LQFP] ST-32-2
ADM1168ASTZ-RL7 −40°C to +85°C 32-Lead Low Profile Quad Flat Package [LQFP] ST-32-2
EVAL-ADM1168LQEBZ Evaluation Board
1 Z = RoHS Compliant Part.
ADM1168
Rev. 0 | Page 28 of 28
NOTES
©2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09474-0-4/11(0)
