Super Sequencer and Monitor
ADM1068
Rev. C
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FEATURES
Complete supervisory and sequencing solution for up to
8 supplies
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
N-FET (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
For more information about the ADM1068 register map,
refer to the AN-721 Application Note at www.analog.com.
FUNCTIONAL BLOCK DIAGRAM
04734-001
PDO7
PDO8
PDOGND
VDD
ARBITRATOR
GND
VCCP
VX1
VX2
VX3
VX4
VP1
VP2
VP3
VH
AGND
V
DDC
A
P
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
EEPROM
ADM1068
CONFIGURABLE
OUTPUT
DRIVERS
(HV CAPABLE OF
DRIVING GATES
OF N-FET)
Figure 1.
GENERAL DESCRIPTION
The ADM1068 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 N-FET 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.
The ADM1068 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.
ADM1068
Rev. C | Page 2 of 24
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 ADM1068................................................................ 10
Inputs................................................................................................ 11
Supply Supervision..................................................................... 11
Programming the Supply Fault Detectors............................... 11
Input Comparator Hysteresis.................................................... 11
Input Glitch Filtering ................................................................. 12
Supply Supervision with VXx Inputs....................................... 12
VXx Pins as Digital Inputs ........................................................ 12
Outputs ............................................................................................ 13
Supply Sequencing Through Configurable Output Drivers. 13
Default Output Configuration.................................................. 13
Sequencing Engine......................................................................... 14
Overview ..................................................................................... 14
Warnings...................................................................................... 14
SMBus Jump (Unconditional Jump)........................................ 14
Sequencing Engine Application Example............................... 15
Fault and Status Reporting........................................................ 16
Applications Diagram.................................................................... 17
Communicating with the ADM1068........................................... 18
Configuration Download at Power-Up................................... 18
Updating the Configuration ..................................................... 18
Updating the Sequencing Engine............................................. 19
Internal Registers........................................................................ 19
EEPROM ..................................................................................... 19
Serial Bus Interface..................................................................... 19
SMBus Protocols for RAM and EEPROM.............................. 21
Write Operations........................................................................ 21
Read Operations......................................................................... 23
Outline Dimensions ....................................................................... 24
Ordering Guide .......................................................................... 24
REVISION HISTORY
6/11—Rev. B to Rev. C
Changes to Serial Bus Timing Parameter in Table 1.................... 4
Changes to Ordering Guide .......................................................... 24
5/08—Rev. A to Rev. B
Changes to Table 1............................................................................ 4
Changes to Powering the ADM1068 Section ............................. 10
Changes to Default Output Configuration Section ................... 13
Changes to Sequence Detector Section ....................................... 16
Changes to Table 9.......................................................................... 19
Changes to Figure 35 and Error Correction Section ................. 23
Changes to Ordering Guide .......................................................... 24
7/06—Rev. 0 to Rev. A
Changes to Features ..........................................................................1
Changes to Table 1.............................................................................4
Changes to Table 2.............................................................................6
Changes to Table 3.............................................................................7
Inserted Table 4; Renumbered Sequentially ..................................7
Changes to Programming the Supply Fault Detectors Section ..... 11
Changes to Outputs Section.......................................................... 14
Changes to Fault Reporting Section ............................................ 19
Changes to Figure 23...................................................................... 20
Inserted Table 9, Renumbered Sequentially ............................... 23
Change to Ordering Guide............................................................ 28
1/05—Revision 0: Initial Version
ADM1068
Rev. C | Page 3 of 24
DETAILED BLOCK DIAGRAM
04734-002
GPI SIGNAL
CONDITIONING
SFD
GPI SIGNAL
CONDITIONING
SFD
SFD
SFD
SELECTABLE
ATTENUATOR
SELECTABLE
ATTENUATOR
DEVICE
CONTROLLER
OSC
EEPROM
SDA SCL A1 A0
SMBus
INTERFACE
ADM1068
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
V
DDC
A
P
Figure 2. Detailed Block Diagram
ADM1068
Rev. C | Page 4 of 24
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 PDO 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 % 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
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
ADM1068
Rev. C | Page 5 of 24
Parameter Min Typ Max Unit Test Conditions/Comments
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 TIMING3
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 5 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.
3 Timing specifications are guaranteed by design and supported by characterization data.
ADM1068
Rev. C | Page 6 of 24
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
ADM1068
Rev. C | Page 7 of 24
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
04734-003
124
25
32
8
9
17
16
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
NC = NO CONNECT
PIN 1
INDICATOR
ADM1068
TOP VIEW
(Not to Scale)
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
11, 13 to 16 NC No Connection.
1 to 4 VX1 to VX4
(VXx)
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
(VPx)
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 6.0 V, from 1.25 V to 3.00 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 6.0 V to 14.4 V and from 2.5 V to 6.0 V.
9 AGND1 Ground Return for Input Attenuators.
10 REFGND1 Ground Return for On-Chip Reference Circuits.
12 REFOUT
Reference Output, 2.048 V. Note that the capacitor must 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, VH pins to a typical of 4.75 V. Note that the
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.
ADM1068
Rev. C | Page 8 of 24
TYPICAL PERFORMANCE CHARACTERISTICS
6
0
1
2
3
4
5
0654321
04734-050
V
VP1
(V)
V
VDDCAP
(V)
Figure 4. VVDDCAP vs. VVP1
6
0
1
2
3
4
5
011412108642
04734-051
V
VH
(V)
V
VDDCAP
(V)
6
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
04734-052
V
VP1
(V)
I
VP1
(mA)
Figure 6. IVP1 vs. VVP1 (VP1 as Supply)
180
160
140
120
100
80
60
40
20
0
0123456
04734-053
VVP1 (V)
IVP1 (µA)
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
04734-054
V
VH
(V)
I
VH
(mA)
6
Figure 8. IVH vs. VVH (VH as Supply)
350
300
250
200
150
100
50
0
0654321
04734-055
VVH (V)
IVH (µA)
Figure 9. IVH vs. VVH (VH Not as Supply)
ADM1068
Rev. C | Page 9 of 24
14
12
10
8
6
4
2
0
0112.510.07.55.02.5
04734-056
ILOAD (µA)
CHARGE-PUMPED VPDO1 (V)
5.0
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
04734-057
I
LOAD
(mA)
V
PDO1
(V)
VP1 = 5V
VP1 = 3V
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
04734-058
ILOAD (µA)
VPDO1 (V)
0
VP1 = 5V
VP1 = 3V
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
04734-061
TEMPERATURE (°C)
REFOUT (V)
VP1 = 3.0V
VP1 = 4.75V
Figure 13. REFOUT vs. Temperature
ADM1068
Rev. C | Page 10 of 24
POWERING THE ADM1068
The ADM1068 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 ADM1068 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 VH input pin can accommodate supplies up to 14.4 V, which
allows the ADM1068 to be powered using a 12 V backplane supply.
In cases where this 12 V supply is hot swapped, it is recommended
that the ADM1068 not be connected directly to the supply. Suitable
precautions, such as the use of a hot swap controller, should be
taken to protect the device from transients that could 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
VDDCAP
INTERNAL
DEVICE
SUPPLY
04734-022
Figure 14. VDD Arbitrator Operation
ADM1068
Rev. C | Page 11 of 24
INPUTS
SUPPLY SUPERVISION
The ADM1068 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 ADM1068 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 ADM1068 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 thresh-
olds can be programmed to an 8-bit resolution in registers provided
in the ADM1068. 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 discussed in the AN-721 Application Note at www.analog.com)
is given by
N = 255 × (5 − 2.5)/3.5
Therefore, N = 182 (1011 0110 or 0xB6).
INPUT COMPARATOR HYSTERESIS
The UV and OV comparators shown in Figure 15 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.
04734-023
+
–
+
–
UV
COMPARATOR
VREF
FAULT TYPE
SELECT
OV
COMPARATOR
FAULT
OUTPUT
GLITCH
FILTER
VPx
MID
LOW
RANGE
SELECT
ULTRA
LOW
Figure 15. Supply Fault Detector Block
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.
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 N/A N/A 0 to 100
ADM1068
Rev. C | Page 12 of 24
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 16.
04734-024
t
0
t
GF
t
0
t
GF
t
0
t
GF
t
0
t
GF
INPUT
INPUT PULSE SHORTER
THAN GLITCH FILTER TIMEOUT
INPUT PULSE LONGE
R
THAN GLITCH FILTER TIMEOUT
OUTPUT
PROGRAMMED
TIMEOUT
PROGRAMMED
TIMEOUT
INPUT
OUTPUT
Figure 16. Input Glitch Filter Function
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
ADM1068 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 discussed in the Supply Supervision with VXX Inputs section,
the VXx input pins on the ADM1068 have dual functionality.
The second function is as a digital logic input to the device.
Therefore, the ADM1068 can be configured for up to four digital
inputs. These inputs are TTL-/CMOS-compatible. 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, once 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.
04734-027
DETECTOR
VXx
(DIGITAL INPUT)
GLITCH
FILTER
VREF = 1.4V
TO
SEQUENCING
ENGINE
+
–
Figure 17. VXx Digital Input Function
ADM1068
Rev. C | Page 13 of 24
OUTPUTS
SUPPLY SEQUENCING THROUGH
CONFIGURABLE OUTPUT DRIVERS
Supply sequencing is achieved with the ADM1068 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 ADM1068 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,
no warnings are received from any of the inputs of the device,
and at other times. The PDOs can be used for a variety of func-
tions. 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 N-FET, 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 configu-
ration 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 ADM1068
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 ADM1068 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
04734-028
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
Figure 18. Programmable Driver Output
ADM1068
Rev. C | Page 14 of 24
SEQUENCING ENGINE
OVERVIEW
The ADM1068 sequencing engine (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, among others. 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:
• Monitors signals indicating the status of the eight input
pins, VP1 to VP3, VH, and VX1 to VX4.
• 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.
• Output condition of the eight PDO pins is defined and
fixed within a state.
• Transition from one state to the next is made in less than
20 μs, which is the time needed to download a state
definition from EEPROM to the SE.
04734-029
SEQUENCE
TIMEOUT
MONITOR
FAULT STATE
Figure 19. State Cell
The ADM1068 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.
ADM1068
Rev. C | Page 15 of 24
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 VP1 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.
04734-032
SUPPLY FAULT
DETECTION
LOGIC INPUT CHANGE
OR FAULT DETECTION
WARNINGS
FORCE FLOW
(UNCONDITIONAL JUMP)
VP1
VX4
INVERT
SEQUENCE
DETECTOR
SELECT
TIMER
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.
04734-030
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
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
ADM1068
Rev. C | Page 16 of 24
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 VP1, VP2, or VP3 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.
04734-033
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
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 ADM1068 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 ADM1068 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. Note that
the data in the status registers is not latched in any way and,
therefore, is subject to change at any time.
See the AN-721 Application Note at www.analog.com for full
details about the ADM1068 registers.
ADM1068
Rev. C | Page 17 of 24
APPLICATIONS DIAGRAM
04734-068
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
ADM1068
PWRGD
RESET
Figure 23. Applications Diagram
ADM1068
Rev. C | Page 18 of 24
COMMUNICATING WITH THE ADM1068
CONFIGURATION DOWNLOAD AT POWER-UP
The configuration of the ADM1068 (undervoltage/overvoltage
thresholds, glitch filter timeouts, PDO configurations, and so on)
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 ADM1068 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 ADM1068, 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 ADM1068 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 ADM1068 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
ADM1068 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 Option 3 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 Option 1. 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 Option 3, restoring the ADM1068 to its
original configuration.
The topology of the ADM1068 makes this type of operation
possible. The local, volatile registers (RAM) are all double-
buffered latches. Setting Bit 0 of the UPDCFG register to 1
leaves the double-buffered latches open at all times. 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 at
www.analog.com. A flow diagram for download at power-up
and subsequent configuration updates is shown in Figure 24.
ADM1068
Rev. C | Page 19 of 24
04734-035
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)
Figure 24. Configuration Update Flow Diagram
UPDATING THE SEQUENCING ENGINE
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 ADM1068 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
ADM1068, 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 ADM1068.
EEPROM
The ADM1068 has two 512-byte cells of nonvolatile, electrically
erasable, programmable, read-only memory (EEPROM), from
Register Address 0xF800 to Register Address 0xFBFF. The
EEPROM is used for permanent storage of data that is not lost
when the ADM1068 is powered down. One EEPROM cell contains
the configuration data of the device; the other 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 6, starting at Address 0xF800, hold the
configuration data for the applications on the ADM1068 (such
as the SFDs and PDOs). These EEPROM addresses are the same
as the RAM register addresses, prefixed by F8. Page 7 is reserved.
Page 8 to Page 15 are for customer use.
Data can be downloaded from the EEPROM to the RAM in one
of the following ways:
• At power-up, when Page 0 to Page 6 are downloaded.
• By setting Bit 0 of the UDOWNLD register (0xD8), which
performs a user download of Page 0 to Page 6.
SERIAL BUS INTERFACE
The ADM1068 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 ADM1068 to download from its EEPROM.
Therefore, access to the ADM1068 is restricted until the download
is complete.
Identifying the ADM1068 on the SMBus
The ADM1068 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 ADM1068s to one SMBus.
Table 9. Serial Bus Slave Address
A1 Pin A0 Pin Hex Address 7-Bit Address
Low Low 0x88 1000100x1
Low High 0x8A 1000101x1
High Low 0x8C 1000110x1
High High 0x8E 1000111x1
1 x = Read/Write bit. The address is shown only as the first 7 MSBs.
ADM1068
Rev. C | Page 20 of 24
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 as follows:
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
could 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.
04734-036
19 91
1919
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
Figure 25. General SMBus Write Timing Diagram
ADM1068
Rev. C | Page 21 of 24
9
04734-037
19 91
191
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
Figure 26. General SMBus Read Timing Diagram
04734-038
SCL
SDA
PS S P
tSU;STO
tHD;STA
tSU;STA
tSU;DAT
tHD;DAT
tHD;STA tHIGH
tBUF
tLOW
tRtF
Figure 27. Serial Bus Timing Diagram
SMBus PROTOCOLS FOR RAM AND EEPROM
The ADM1068 contains volatile registers (RAM) and nonvolatile
registers (EEPROM). User RAM occupies Address 0x00 to
Address 0xDF; 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 ADM1068 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 ADM1068, 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.
04734-039
2413
SLAVE
ADDRESS
RAM
ADDRESS
(0x00 TO 0xDF)
SWA A
56
P
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.
ADM1068
Rev. C | Page 22 of 24
56
P
The master sends a command code telling the slave device
to erase the page. The ADM1068 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.
04734-040
2413
SLAVE
ADDRESS
COMMAND
BYTE
(0xFE)
SWA A
Figure 29. EEPROM Page Erasure
As soon as the ADM1068 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 ADM1068 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 ADM1068, 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.
04734-041
SLAVE
ADDRESS
RAM
ADDRESS
(0x00 TO 0xDF)
S W A DATAAPA
2413 576 8
Figure 30. Single Byte Write to the RAM
• 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.
04734-042
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 76 8
Figure 31. Setting an EEPROM Address
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.
• 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.
04734-043
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 7
A
9
DATA
86 10
Figure 32. Single Byte Write to the EEPROM
Block Write
In a block write operation, the master device writes a block of
data to a slave device. The start address for a block write must
have been set previously. In the ADM1068, a send byte opera-
tion sets a RAM address, and a write byte/word operation sets
an EEPROM address, 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 write. The ADM1068 command
code for a block write is 0xFC (1111 1100).
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.
04734-044
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
Figure 33. Block Write to the EEPROM or RAM
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.
ADM1068
Rev. C | Page 23 of 24
6
8. The slave asserts ACK on SDA.
9. The ADM1068 sends a byte-count data byte that tells th
master how many data bytes to expect. The ADM1068
always returns 32 data bytes (0x20), whic
• An address crosses a page boundary. In this case, both
pages must be erased before programming. e
h is the maximum
tion.
13. sserts a stop condition on SDA to end the
transaction.
Note that the ADM1068 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 ADM1068 pulls SCL low and
extends the clock pulse when it cannot accept any
more data.
allowed by the SMBus 1.1 specifica
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.
The master a
READ OPERATIONS
The ADM1068 uses the following SMBus read protocols.
04734-046
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
Receive Byte
In a receive byte operation, the master device receives a single
byte from 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
read bit (high). Figure 35. Block Read from the EEPROM or RAM
ead
as a block read for Step 1 to Step 12 and then proceeds
d issues another block read, if the
generated after the PEC byte
15. ts a stop condition on SDA to end
chec rms to CRC-8 by the polynomial
f a block read with the optional PEC byte is shown
in Figure 36.
3. The addressed slave device asserts ACK on SDA. Error Correction
The ADM1068 provides the option of issuing a packet error
correction (PEC) byte after a write to the RAM, a write to the
EEPROM, a block write to the RAM/EEPROM, or a block r
from the RAM/ EEPROM. This option enables the user to
verify that the data received by or sent from the ADM1068 is
correct. The PEC byte is an optional byte sent after that last data
byte has been written to or read from the ADM1068. The protocol
is the same
4. The master receives a data byte.
5. The master asserts NACK on SDA.
6. The master asserts a stop condition on SDA, and the
transaction ends.
In the ADM1068, 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 34.
as follows:
13. The ADM1063 issues a PEC byte to the master. The master
checks the PEC byte an
04734-045
23145
SLAVE
ADDRESS
S R DATA PA A
PEC byte is incorrect.
14. A no acknowledge (NACK) is
Figure 34. Single Byte Read from the EEPROM or RAM
Block Read to signal the end of the read.
The master asser
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 ADM1068, 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:
the transaction.
Note that the PEC byte is calculated using CRC-8. The frame
k sequence (FCS) confo
C(x) = x8 + x2 + x1 + 1
See the SMBus 1.1 specification for details.
An example o
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).
04734-047
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
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 ADM1068 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. Figure 36. Block Read from the EEPROM or RAM with PEC
7. The master sends the 7-bit slave address followed by the
read bit (high).
ADM1068
Rev. C | Page 24 of 24
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
ADM1068ASTZ −40°C to +85°C 32-Lead LQFP ST-32-2
ADM1068ASTZ-REEL7 −40°C to +85°C 32-Lead LQFP ST-32-2
EVAL-ADM1068LQEBZ Evaluation Board
1 Z = RoHS Compliant Part.
©2005–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D04734-0-6/11(C)
