Digital Power Monitor with
PMBus Interface
Data Sheet ADM1293/ADM1294
Rev. B Document Feedbac
k
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FEATURES
Monitor current and two voltages
High accuracy current monitoring at low sense voltage
0.33% accurate at ±20 mV sense voltage over temperature
Common-mode sense voltage from 0 V to 20 V (ADM1293)
Support high-side and low-side current sensing
Integrated shunt regulator for wide supply input (ADM1294)
Reports current, voltage, and power
Power accumulation for energy metering
Bidirectional current sensing
Digitally programmable overcurrent alert
Multifunctional pins with user configurable functions
ADC conversion enable input
Multisource alert output
User-controllable GPO
Peak detect registers for current, voltage, and power
PMBus fast mode compliant interface
Separate SDA I/O for easy isolated communication
Two address pins for 16 unique I²C addresses
Available in 4 mm × 4 mm, 16-lead LFCSP and 14-lead TSSOP
Operation temperature range
ADM1293 TA = −40°C to +105°C
ADM1294 TJ = −40°C to +105°C
APPLICATIONS
Power monitoring/power budgeting
Central office equipment
Telecommunications and data communications equipment
PCs/servers
FUNCTIONAL BLOCK DIAGRAMS
Figure 1. ADM1293 Functional Block Diagram
Figure 2. ADM1294 Functional Block Diagram
GENERAL DESCRIPTION
The ADM1293 and ADM1294 are high accuracy integrated digital
power monitors that offer digital current, voltage, and power
monitoring using an on-chip, 12-bit analog-to-digital converter
(ADC), communicated through a PMBus™ compliant I2C interface.
These devices acquire the current by measuring the voltage differ-
ence across the external sense resistor. This voltage is amplified
and digitized by an internal 12-bit ADC. The same ADC can also
sample the primary input voltage and an auxiliary input voltage.
The internal digital block can perform multiplication of the
current and primary input voltage for power calculation. The
ADM1293/ADM1294 also feature a power accumulator for
energy metering. An industry-standard PMBus interface allows a
master controller to read back these data from the device. The
master controller can then combine this information with a known
sense resistor value to calculate the current, voltage, power, and
energy consumption over time on the monitored rail.
In conditions such as overcurrent, overvoltage, undervoltage,
and overpower, the ADM1293/ADM1294 devices can generate
an interrupt signal to the microprocessor through the
GPOx/ALERTx outputs. The threshold for these conditions is
digitally programmed via PMBus.
The ADM1293 is designed for high-side supply monitoring
with a voltage monitoring range from 0 V to 20 V. The
ADM1294 is designed for low-side supply monitoring. Its
integrated shunt regulator allows it to be powered and to
monitor supply in wide voltage ranges.
The ADM1293/ADM1294 are available in 4 mm × 4 mm 16-lead
LFCSP and 14-lead TSSOP packages with a specified operating
ambient temperature range from −40°C to +105°C for the
ADM1293 and an operating junction temperature range from
−40°C to +105°C for the ADM1294.
SENSEP
V
AUX
SENSEN
MUX
PMBUS AND LOG I C
ADDRESS
DECODER
LDO
INTERNAL
SUPPLY
ADM1293
SDAISCLADR1 GNDADR2 SDAO
GPO1/ALERT1/CONV
GPO2/ALERT2
VIN RANGE
SELECT
11891-001
ADCEN
VCC
VCAP
SENSEN
VAUX
SENSEP
MUX PMBUS
AND
LOGIC
ADDRESS
DECODER
ADM1294
SDAI
ADR1
ADR2
SCL
SDAO
GPO1/ALERT1/CONV
GPO2/ALERT2
VIN
VEE
RANGE
SELECT
IC POWER SUPPLY
11891-002
ADC
EN
V
SHUNT
VCAP LDO VEE
ADM1293/ADM1294 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagrams ............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 3
Specifications ..................................................................................... 4
Electrical Characteristics ............................................................. 4
Serial Bus Timing Characteristics .............................................. 7
Absolute Maximum Ratings ............................................................ 8
Thermal Characteristics .............................................................. 8
ESD Caution .................................................................................. 8
Pin Configurations and Function Descriptions ........................... 9
Typical Performance Characteristics ........................................... 11
Theory of Operation ...................................................................... 14
Powering the ADM1293 ............................................................ 14
Powering the ADM1294 ............................................................ 14
Optional Power Monitor Inputs Filtering ............................... 16
Power Monitor ............................................................................ 16
PMBus Interface ............................................................................. 18
Device Addressing ...................................................................... 18
SMBus Protocol Usage ............................................................... 19
Packet Error Checking ............................................................... 19
Partial Transactions on I2C Bus ................................................ 19
SMBus Message Formats ........................................................... 19
Group Commands ...................................................................... 21
Information Commands ............................................................ 21
Status Commands ....................................................................... 21
GPOx and ALERTx Pin Setup Commands ............................ 22
Power Monitor Commands ...................................................... 22
Warning Limit Setup Commands ............................................ 24
PMBus Direct Format Conversion .......................................... 24
Energy Meter Value Conversion .............................................. 26
Energy Meter Value to PMBus Standard Data Conversion .. 27
Voltage and Current Conversion Using LSB Values .............. 27
ALERTx Pin Behavior .................................................................... 28
Warnings ...................................................................................... 28
Generating an Alert .................................................................... 28
Handling/Clearing an Alert ...................................................... 28
SMBus Alert Response Address (ARA) .................................. 28
Example Use of SMBus ARA .................................................... 29
Digital Comparator Mode ......................................................... 29
Application Diagrams .................................................................... 30
PMBus Command Reference........................................................ 32
PMBus Command Descriptions .................................................. 33
Clear Faults Register .................................................................. 33
PMBus Capability Register ....................................................... 33
IOUT OC Warning Limit Register .......................................... 33
VIN OV Warning Limit Register ............................................. 33
VIN UV Warning Limit Register ............................................. 34
PIN OP Warning Limit Register .............................................. 34
Status Byte Register .................................................................... 34
Status Word Register .................................................................. 34
IOUT Status Register ................................................................. 35
Input Status Register .................................................................. 35
Manufacturer Specific Status Register ..................................... 36
Read EIN Register ...................................................................... 36
Read EOUT Register .................................................................. 37
Read VIN Register...................................................................... 37
Read IOUT Register ................................................................... 37
Read PIN Register ...................................................................... 37
PMBus Revision Register .......................................................... 38
Manufacturer ID Register ......................................................... 38
Manufacturer Model Register ................................................... 38
Manufacturer Revision Register ............................................... 38
Maximum IOUT Register ......................................................... 38
Peak VIN Register ...................................................................... 39
Peak VAUX Register .................................................................. 39
Power Monitor Control Register .............................................. 39
Power Monitor Configuration Register................................... 40
Alert 1 Configuration Register ................................................. 41
Alert 2 Configuration Register ................................................. 41
Device Configuration Register ................................................. 42
Maximum PIN Register............................................................. 42
Read PIN (Extended) Register ................................................. 43
Read EIN (Extended) Register ................................................. 43
Read VAUX Register .................................................................. 43
VAUX OV Warning Limit Register ......................................... 43
VAUX UV Warning Limit Register ......................................... 44
Minimum IOUT Register.......................................................... 44
Minimum PIN Register ............................................................. 44
Rev. B | Page 2 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 3 of 48
Read EOUT (Extended) Register .............................................. 44
Hysteresis Low Threshold Level Register ................................ 45
Hysteresis High Threhsold Level Register ............................... 45
Hysteresis Status Register ........................................................... 45
Outline Dimensions ........................................................................ 46
Ordering Guide ........................................................................... 47
REVISION HISTORY
3/15—Rev. A to Rev. B
Changes to Power Monitor Section .............................................. 16
Added Table 7 .................................................................................. 17
Changes to Energy Meter Value Conversion Section ................. 26
Changes to Table 23 ........................................................................ 36
Changes to Table 24 ........................................................................ 37
Changes to Table 42 ........................................................................ 43
Changes to Table 48 ........................................................................ 44
Changes to Ordering Guide ........................................................... 47
10/14—Rev. 0 to Rev. A
Changes to Figure 19 ...................................................................... 14
Added Table 7; Renumbered Sequentially ................................... 20
8/14—Revision 0: Initial Version
ADM1293/ADM1294 Data Sheet
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
For the ADM1293: VCC = 2.95 V to 20 V, VSENSEP = 0 V to 20 V, VCC ≥ VSENSEP, VCC ≥ VSENSEN, TA = −40°C to +105°C, unless otherwise noted.
For the ADM1294: VEE = −48 V, shunt regulation current = 10 mA, VSENSEP = VEE = 0 V, pin voltages are referenced to the VEE pin, TJ =
−40°C to +105°C, unless otherwise noted. All minimum/maximum specifications apply over the entire recommended operating range,
unless otherwise noted. Typical values are specified at TA = 25°C.
Table 1.
Parameter Symbol Min Typ Max Unit Test Conditions/Comments
POWER SUPPLY
ADM1293
Operating Voltage Range VOP3 2.95 20 V
Undervoltage Lockout (UVLO) VUVLO_3 2.4 2.7 V VCC rising
UVLO Hysteresis 90 120 mV
Quiescent Current ICC3 3.3 mA
ADM1294
Typical Operating Voltage VOP4 2.95 VSHUNT V Reference to VEE
Voltage Transient Immunity 200 V
Shunt Regulation Voltage VSHUNT 11.5 12.3 13 V IIN = 3.3 mA to 30 mA, maximum IIN dependent on TA and
θJA (see the Powering the ADM1294 section)
Undervoltage Lockout VUVLO_4 2.4 2.7 V VSHUNT rising
UVLO Hysteresis 90 120 mV
Quiescent Current ICC4 3.6 mA VSHUNT = 13 V
Power Directly Without Shunt VDIR 2.95 11.5 V
SENSEP AND SENSEN PINS
ADM1293
Input Current IIN_SENSE3 ±25 nA Per individual pin, VSENSEP = VSENSEN = VCC = 20 V
Input Imbalance IΔSENSE3 ±5 ±25 nA IΔSENSEx = ISENSEP − ISENSEN, VSENSE = ±20 mV, VSENSEP = VVSHUNT
ADM1294
Input Current
I
IN_SENSE4
−1
µA
V
SENSEP
= V
SENSEN
≤ 25 mV, per individual pin, V
VSHUNT
= 12 V
Input Imbalance IΔSENSE4 ±0.05 ±1 µA IΔSENSEx = ISENSEP − ISENSEN, VSENSE = ±20 mV, VSENSEP = 0 V, VVSHUNT =
12 V
VCAP PIN
Internally Regulated Voltage VVCAP 2.66 2.7 2.74 V 0 µA ≤ IVCAP ≤ 100 µA, CVCAP = 1 μF
VIN PIN
Input Current
I
VIN
20
µA
V
VIN
= 20 V, V
RANGE
= 0 V to 21 V
±100 nA VVIN = 1.2 V, VRANGE = 0 V to 1.2 V
VAUX PIN
Input Current IVAUX ±100 nA VVAUX = 1.2 V, VAUX sampling enabled
GPO1/ALERT1/CONV PIN
Output Low Voltage
V
OL_GPO1
0.4
V
I
GPO1
= 1 mA
1.5 V IGPO1 = 5 mA
Leakage Current ±100 nA VGPO1 ≤ 2 V, GPO1 output high-Z
1 µA VGPO1 = 20 V, GPO1 output high-Z
Input High Voltage VIH 1.1 V Configured as CONV pin
Input Low Voltage VIL 0.8 V Configured as CONV pin
Glitch Filter 1 µs Configured as CONV pin
GPO2/ALERT2 PIN
Output Low Voltage VOL_GPO2 0.4 V IGPO2 = 1 mA
1.5 V IGPO2 = 5 mA
Leakage Current ±100 nA VGPO2 ≤ 2 V, GPO2 output high-Z
±1 µA VGPO2 = 20 V, GPO2 output high-Z
Rev. B | Page 4 of 48
Data Sheet ADM1293/ADM1294
Parameter Symbol Min Typ Max Unit Test Conditions/Comments
GRADE A DEVICE CURRENT AND
VOLTAGE MONITORING
Current Sense Absolute Error 128 sample averaging, VSENSEP = 0 V to 18 V (unless
otherwise noted)
Current Sense Range (CSR) =
±25 mV
0.04
0.33
%
V
SENSE
= V
SENSEP
− V
SENSEN
= ±20 mV, T
A
= −40°C to +85°C
0.38 % VSENSE = ±20 mV
0.72 % VSENSE = ±20 mV, 16 sample averaging
2.65 % VSENSE = ±20 mV, one sample averaging
1 % VSENSE = ±20 mV, VSENSEP = 18 V to 20 V
0.35 % VSENSE = ±25 mV
0.44 % VSENSE = ±15 mV
0.59 % VSENSE = ±10 mV
1 % VSENSE = ±5 mV
2 % VSENSE = ±2.5 mV
5 % VSENSE = ±1 mV
CSR = ±50 mV 0.26 % VSENSE = ±40 mV
0.4 % VSENSE = ±20 mV
CSR = ±100 mV 0.23 % VSENSE = ±80 mV
0.3 % VSENSE = ±40 mV
CSR = ±200 mV
0.21
%
V
SENSE
= ±160 mV
0.27
%
V
SENSE
= ±80 mV
Voltage Sense Absolute Error 128 sample averaging
VIN 0.35 % VVIN = 10 V to 20 V, VRANGE = 21 V
0.26 % VVIN = 3.6 V to 7.4 V, VRANGE = 7.4 V
0.2 % VVIN = 0.6 V to 1.2 V, VRANGE = 1.2 V, TA = −40°C to +85°C
0.24 % VVIN = 0.6 V to 1.2 V, VRANGE = 1.2 V
VAUX 0.2 % VVAUX = 0.6 V to 1.2 V, TA = −40°C to +85°C
0.24 % VVAUX = 0.6 V to 1.2 V
Power Absolute Error 0.48 % VSENSE = ±20 mV, SENSEP = VIN = 12 V, VRANGE = 21 V, TA =
−40°C to +85°C
0.54 % VSENSE = ±20 mV, SENSEP = VIN = 12 V, VRANGE = 21 V
0.5
%
V
SENSE
= ±20 mV, SENSEP = VIN = 3.3 V, V
RANGE
= 7.4 V, T
A
=
−40°C to +85°C
0.54 % VSENSE = ±20 mV, SENSEP = VIN = 3.3 V, VRANGE = 7.4 V
0.48 % VSENSE = ±20 mV, SENSEP = 20 mV, VIN = 0.8 V, VRANGE =
1.2 V, TA = −40°C to +85°C
0.53 % VSENSE = ±20 mV, SENSEP = 20 mV, VIN = 0.8 V, VRANGE = 1.2 V
GRADE B DEVICE CURRENT AND
VOLTAGE MONITORING
Current Sense Absolute Error 128 sample averaging (unless otherwise noted)
CSR = ±25 mV 0.1 0.75 % VSENSE = VSENSEP − VSENSEN = ±20 mV, TA = −40°C to +85°C
0.84 % VSENSE = ±20 mV
1.6 % VSENSE = ±20 mV, 16 sample averaging
5.8 % VSENSE = ±20 mV, one sample averaging
2.2
%
V
SENSE
= ±20 mV, V
SENSEP
= 18 V to 20 V
0.8
%
V
SENSE
= ±25 mV
1 % VSENSE = ±15 mV
1.3 % VSENSE = ±10 mV
4.5 % VSENSE = ±2.5 mV
11 % VSENSE = ±1 mV
CSR = ±50 mV 0.57 % VSENSE = ±40 mV
0.9 % VSENSE = ±20 mV
Rev. B | Page 5 of 48
ADM1293/ADM1294 Data Sheet
Parameter Symbol Min Typ Max Unit Test Conditions/Comments
CSR = ±100 mV 0.55 % VSENSE = ±80 mV
0.7 % VSENSE = ±40 mV
CSR = ±200 mV 0.5 % VSENSE = ±160 mV
0.6 % VSENSE = ±80 mV
Voltage Sense Absolute Error
128 sample averaging
VIN 0.8 % VVIN = 10 V to 20 V, VRANGE = 21 V
0.6 % VVIN = 3.6 V to 7.4 V, VRANGE = 7.4 V
0.45 % VVIN = 0.6 V to 1.2 V, VRANGE = 1.2 V, TA = −40°C to +85°C
0.6 % VVIN = 0.6 V to 1.2 V, VRANGE = 1.2 V
VAUX 0.45 % VVAUX = 0.6 V to 1.2 V, TA = −40°C to +85°C
0.6 % VVAUX = 0.6 V to 1.2 V
Power Absolute Error 1.2 % VSENSE = ±20 mV, SENSEP = VIN = 12 V, VRANGE = 21 V
1.2 % VSENSE = ±20 mV, SENSEP = VIN = 3.3 V, VRANGE = 7.4 V
1.2 % VSENSE = ±20 mV, SENSEP = 20 mV, VIN = 0.8 V, VRANGE = 1.2 V
ADC CONVERSION TIME Includes time for power multiplication
144 165 µs One sample of IOUT, from command received to valid
data in register
64 73 µs One sample of VIN, from command received to valid data
in register
64 73 µs One sample of VAUX, from command received to valid
data in register
ADRx PINS
Address Set to 00 0 0.8 V Connect to VEE
Input Current for Address 00 −40 −22 μA VADRx = 0 V to 0.8 V
Address Set to 01 135 150 165 kΩ Resistor to VEE
Address Set to 10 −1 +1 μA No connect state, maximum leakage current allowed
Address Set to 11 2 V Connect to VCAP
Input Current for Address 11 3 10 μA VADRx = 2.0 V to VCAP, must not exceed the maximum
allowable current draw from VCAP
SERIAL BUS DIGITAL I/O SDAI, SDAO, SCL
Input High Voltage VIH 1.1 V
Input Low Voltage VIL 0.8 V
SDAO Output Low Voltage VOL 0.4 V IOL = 4 mA
Input Leakage ILEAK_PIN −10 +10 μA
−5 +5 μA Device is not powered
Nominal Bus Voltage
V
DD
2.7
5.5
V
3 V to 5 V ± 10%
Capacitance for I/O Pins CPIN 5 pF
Input Glitch Filter tSP 0 50 ns
Rev. B | Page 6 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 7 of 48
SERIAL BUS TIMING CHARACTERISTICS
Table 2.
Parameter Description Min Typ Max Unit
fSCLK Clock frequency 400 kHz
tBUF Bus free time 1.3 μs
tHD;STA Start hold time 0.6 μs
tSU;STA Start setup time 0.6 μs
tSU;STO Stop setup time 0.6 μs
tHD;DAT SDA hold time 300 900 ns
tSU;DAT SDA setup time 100 ns
tLOW SCL low time 1.3 μs
tHIGH SCL high time 0.6 μs
tR1 SCL, SDA rise time 20 300 ns
tF SCL, SDA fall time 20 300 ns
1 tR = (VIL(MAX) − 0.15) to (VIH3V3 + 0.15) and tF = 0.9 VDD to (VIL(MAX) − 0.15), where VIH3V3 = 2.1 V, and VDD = 3.3 V.
Serial Bus Timing Diagram
Figure 3. Serial Bus Timing Diagram
t
LOW
t
BUF
t
HD;DAT
t
SU;DAT
t
SU;STA
t
HD;STA
t
HIGH
t
R
t
F
t
SU;STO
PSSP
VIH
VIL
VIH
VIL
SCL
S
DAO/SDAI
11891-003
ADM1293/ADM1294 Data Sheet
Rev. B | Page 8 of 48
ABSOLUTE MAXIMUM RATINGS
Pin voltages on the ADM1293 are referenced to the GND pin
and pin voltages on the ADM1294 are referenced to the VEE pin.
Table 3.
Parameter Rating
VCC Pin −0.3 V to +25 V
VSHUNT Pin −0.3 V to +14 V
VCAP Pin −0.3 V to +4 V
SCL Pin −0.3 V to +6.5 V
SDAI Pin −0.3 V to +6.5 V
SDAO Pin −0.3 V to +6.5 V
ADR1 Pin −0.3 V to VCAP + 0.3 V
ADR2 Pin −0.3 V to VCAP + 0.3 V
GPO1/ALERT1/CONV Pin −0.3 V to +25 V
GPO2/ALERT2 Pin −0.3 V to +25 V
VIN Pin −0.3 V to +25 V
VAUX Pin −0.3 V to +4 V
SENSEP Pin −0.3 V to +25 V
SENSEN Pin −0.3 V to +25 V
Continuous Current into VSHUNT Pin 30 mA
Continuous Current into Any Other Pin ±10 mA
Storage Temperature Range −65°C to +150°C
Operating Ambient Temperature Range
ADM1293 −40°C to +105°C
Operating Junction Temperature Range
ADM1294 −40°C to +105°C
Junction Temperature Range −40°C to +110°C
Lead Temperature, Soldering (10 sec) 300°C
Junction Temperature 150°C
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL CHARACTERISTICS
θJA is specified for the worst case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 4. Thermal Resistance
Package Type θJA Unit
16-Lead LFCSP 50.58 °C/W
14-Lead TSSOP 122.73 °C/W
ESD CAUTION
Data Sheet ADM1293/ADM1294
Rev. B | Page 9 of 48
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
Figure 4. ADM1293 LFCSP Pin Configuration Figure 5. ADM1293 TSSOP Pin Configuration
Table 5. ADM1293 Pin Function Descriptions
Pin No.
Mnemonic Description
LFCSP TSSOP1
16 1 VAUX Auxiliary Voltage Monitoring Input. This pin reads back the auxiliary input voltage using the internal ADC. An
external divider is required to monitor voltages higher than 1.2 V.
1 2 VCC Positive Supply Input. An undervoltage lockout (UVLO) circuit resets the device when a low supply voltage is
detected. A 0.1 μF decoupling capacitor must be placed close to the VCC pin.
2 3 VCAP Internal Regulated Supply. Place a capacitor with a value of 1 μF or greater on this pin to maintain accuracy.
3 4 ADR1 PMBus Address. This pin can be tied low, tied to VCAP, left floating, or tied low through a resistor. Combine
with the ADR2 pin to set up to 16 different PMBus addresses.
4 5 ADR2 PMBus Address. This pin can be tied low, tied to VCAP, left floating, or tied low through a resistor. Combine
with the ADR1 pin to set up to 16 different PMBus addresses.
5 6 SDAI PMBus Serial Data Input. This is a split version of the SDA for easy use with optocouplers. Tie this pin directly
to the SDAO pin if a bus split is not required.
6 7 SDAO PMBus Serial Data Output. This is a split version of the SDA for easy use with optocouplers. Tie this pin
directly to the SDAI pin if a bus split is not required.
7 8 SCL PMBus Serial Clock. Open-drain input. Requires an external resistive pull-up.
8 9 GPO1/ALERT1/CONV General-Purpose Digital Output (GPO1).
Alert (ALERT1). This pin can be configured to generate an alert signal when one or more warning conditions are
detected.
Conversion (CONV). This pin can be used as an input signal to control when a power monitor ADC sampling
cycle begins. This pin defaults to an alert output at power up. There is no internal pull-up on this pin.
9 10
GPO2/ALERT2 General-Purpose Digital Output (GPO2).
Alert (ALERT2). This pin can be configured to generate an alert signal when one or more warning conditions
are detected. This pin defaults to an alert output at power up. There is no internal pull-up on this pin.
10 N/A NIC Not Internally Connected. This pin is not internally connected.
11 11 SENSEN Negative Current Sense Input.
12 12 SENSEP Positive Current Sense Input.
13 13 VIN Primary Voltage Monitoring Input. This pin reads back the primary input voltage using the internal ADC. The
internal divider allows this pin to directly monitor a 20 V supply. An external divider is required to monitor
voltages higher than 20 V.
14 N/A NIC Not Internally Connected. This pin is not internally connected.
15 14 GND Chip Ground. This pin must connect to the lowest potential.
EPAD N/A EPAD Exposed Pad. Solder the exposed pad to the board to improve thermal dissipation. Connect the exposed pad
to GND.
1 N/A means not applicable.
11891-004
12
11
10
1
3
49
2
6
5
7
8
16
15
14
13
NOTES
1. N IC = NOT INTERNALLY CO NN E CTED .
2
. EXPOSED PAD. SOLDER THE EXPOSED PAD TO THE BOARD
TO IMPROVE T HERMAL DISSIPAT I ON. THE EXPOSED PAD CAN
BE C ONNEC TED TO G N D.
VCC
VCAP
ADR1
ADR2
SENSEP
VIN
NIC
GND
VAU
X
SENSEN
NIC
GPO2/ALERT2
SDAI
SDAO
SCL
GPO1/ALERT1/CONV
ADM1293
TOP VIEW
(Not to Scale)
1
2
3
4
5
6
7
VCC
VCAP
ADR1
SDAO
SDAI
ADR2
VAUX
14
13
12
11
10
9
8
VIN
SENSEP
SENSEN
SCL
GPO1/ALERT1/CONV
GPO2/ALERT2
GND
ADM1293
TOP VI EW
(Not to Scale)
11891-005
ADM1293/ADM1294 Data Sheet
Rev. B | Page 10 of 48
Figure 6. ADM1294 LFCSP Pin Configuration Figure 7. ADM1294 TSSOP Pin Configuration
Table 6. ADM1294 Pin Function Descriptions
Pin No.
Mnemonic Description
LFCSP TSSOP1
16 1 VAUX Auxiliary Voltage Monitoring Input. This pin reads back the auxiliary input voltage using the internal ADC. An
external divider is required to monitor voltages higher than 1.2 V.
1 2 VSHUNT Shunt Regulated Positive Supply to Chip. Connect this pin to the positive supply rail. A shunt resistor in series
is required to limit the input current if the supply voltage is higher than the shunt regulation voltage. A 1 μF
decoupling capacitor to VEE is recommended on the VSHUNT pin.
2 3 VCAP Internal Regulated Supply. Place a capacitor with a value of 1 μF or greater on this pin to maintain accuracy.
3 4 ADR1 PMBus Address. This pin can be tied low, tied to VCAP, left floating, or tied low through a resistor. Combine
with the ADR2 pin to set up to 16 different PMBus addresses.
4 5 ADR2 PMBus Address. This pin can be tied low, tied to VCAP, left floating, or tied low through a resistor. Combine
with the ADR1 pin to set up to 16 different PMBus addresses.
5 6 SDAI PMBus Serial Data Input. This is a split version of the SDA for easy use with optocouplers. Tie this pin directly
to the SDAO pin if a bus split is not required.
6 7 SDAO PMBus Serial Data Output. This is a split version of the SDA for easy use with optocouplers. Tie this pin
directly to the SDAI pin if a bus split is not required.
7 8 SCL PMBus Serial Clock. Open-drain input. Requires an external resistive pull-up.
8 9 GPO1/ALERT1/CONV General-Purpose Digital Output (GPO1).
Alert (ALERT1). This pin can be configured to generate an alert signal when one or more warning conditions are
detected.
Conversion (CONV). This pin can be used as an input signal to control when a power monitor ADC sampling
cycle begins. This pin defaults to an alert output at power up. There is no internal pull-up on this pin.
9 10 GPO2/ALERT2 General-Purpose Digital Output (GPO2).
Alert (ALERT2). This pin can be configured to generate an alert signal when one or more warning conditions
are detected. This pin defaults to an alert output at power up. There is no internal pull-up on this pin.
10 N/A NIC Not Internally Connected. This pin is not internally connected.
11 11 SENSEN Negative Current Sense Input.
12 12 SENSEP Positive Current Sense Input.
13 13 VIN Primary Voltage Monitoring Input. This pin reads back the primary input voltage using the internal ADC. The
internal divider allows this pin to directly monitor a 20 V supply. An external divider is required to monitor
voltages higher than 20 V.
14 N/A NIC Not Internally Connected. This pin is not internally connected.
15 14 VEE Chip Ground Pin. This pin must connect to the lowest potential.
EPAD N/A EPAD Exposed Pad. Solder the exposed pad to the board to improve thermal dissipation. Connect the exposed pad
to VEE.
1 N/A means not applicable.
11891-006
12
11
10
1
3
49
2
6
5
7
8
16
15
14
13
NOTES
1. N IC = NOT INTERNALLY CO NN E CTED .
2
. EXPOSED PAD. SOLDER THE EXPOSED PAD TO THE BOARD
TO IMPROVE T HERMAL DISSIPAT I ON. THE EXPOSED PAD CAN
BE CONNECTED TO VEE.
VSHUNT
VCAP
ADR1
ADR2
SENSEP
VIN
NIC
VEE
VAU
X
SENSEN
NIC
GPO2/ALERT2
SDAI
SDAO
SCL
GPO1/ALERT1/CONV
AD1294
TOP VIEW
(Not to Scale)
1
2
3
4
5
6
7
VSHUNT
VCAP
ADR1
SDAO
SDAI
ADR2
VAUX
14
13
12
11
10
9
8
VIN
SENSEP
SENSEN
SCL
GPO1/ALERT1/CONV
GPO2/ALERT2
VEE
ADM1294
TOP VI EW
(Not to Scale)
11891-007
Data Sheet ADM1293/ADM1294
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 8. ICC vs. Pin Voltages
Figure 9. ICC vs. Temperature
Figure 10. VSHUNT Regulation Voltage vs. Temperature
Figure 11. ADM1293 SENSEP/SENSEN Pins Input Current vs.
SENSEP and SENSEN Pin Voltage
Figure 12. ADM1293 Total SENSEP and SENSEN Pins Input Current vs.
SENSEP and SENSEN Pin Voltage
Figure 13. Total SENSEP and SENSEN Input Current vs. Temperature
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 5 10 15 20
I
CC
(mA)
VCC/VSHUNT VOLT AGE (V)
ADM1293
ADM1294
11891-008
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
–40 –20 025 85 105
TEMPERATURE (°C)
VCC = VSHUNT = 3.3V
ICC ( mA)
11891-009
10.0
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
–40 –20 025 85 105
VSHUNT RE GULATION VOLTAGE (V)
TEMPERATURE (°C)
VSHUNT AT I
IN
= 3.3mA
VSHUNT AT I
IN
= 30mA
11891-010
0
20
40
60
80
100
120
0510 15 20
SENSE x P IN I NP UT CURRENT ( nA)
VOLTAGE ON SENSEx PINS (V)
ISENSEP
ISENSEN
11891-011
VCC = 20V
–5
–4
–3
–2
–1
0
1
2
3
4
5
2.95 5.00 10.00 15.00 20.00
TOTAL SENS E x P IN I NP UT CURRENT ( nA)
VOLTAGE ON SENSEx PINS (V)
11891-012
V
SENSEP
= V
SENSEN
= VCC
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
TOTAL SENS E x P IN I NP UT CURRENT ( nA)
–40 –20 025 85 105
TEMPERATURE (°C)
11891-013
V
SENSEP
= V
SENSEN
= VCC/ V S HUNT
Rev. B | Page 11 of 48
ADM1293/ADM1294 Data Sheet
Figure 14. SENSEP and SENSEN Pins Input Current Imbalance vs. SENSEP and
SENSEN Pins Differential Voltage
Figure 15. SENSEN and SENSEP Input Current Imbalance vs. Temperature
Figure 16. VIN Input Current vs. VIN Pin Voltage, VRANGE = 0 V to 7.4 V
or 0 V to 21 V
Figure 17. VIN/VAUX Input Currents vs. VIN/VAUX Voltage
Figure 18. VIN/VAUX Input Currents vs. Temperature
Figure 19. Worst Case Current Sense Error vs. Current Sense Voltage with
128 Sample Averaging, VSENSEP = 0 V to 18 V, over Full Operating
Temperature Range
–80
–60
–40
–20
0
20
40
60
80
–200 –150 –100 –50 050 100 150 200
ISENSEN – ISENSEP (nA)
VSENSEP – VSENSEN (mV)
11891-014
VSENSEP = 12V
VSENSEP = 0V
–5
–4
–3
–2
–1
0
1
2
3
4
5
I
SENSEN
– I
SENSEP
(n A)
–40 –20 025 85 105
TEMPERATURE (°C)
11891-015
VCC = V
SENSEP
= 3.3V
V
SENSEP
– V
SENSEN
= 20mV
–0.5
0.5
1.5
2.5
3.5
4.5
012345678910 11 12 13 14 15 16 17 18 19 20
VIN P IN I NP UT CURRENT (µA)
VOLTAGE ON VIN PIN (V)
11891-016
–6
–4
–2
0
2
4
6
8
02468
11891-017
10 12 14 16 18 20
VIN AND VAUX PI N INPUT CURRE NTS ( nA)
VOLTAGE ON VINAND VAUX PINS (V)
I
VIN
RANGE = 0V TO 1.2V
I
VIN
DISABLED
I
VAUX
RANGE = 0V TO 1.2V
I
VAUX
DISABLED
–10
–8
–6
–4
–2
0
2
4
6
8
10
–40 –10 20 50 80
VIN AND VAUX PI N INPUT CURRE NTS
TEMPERATURE (°C)
VIN= 12V, RANGE = 21V, UNIT: µA
VIN = 0.6V, RANGE=1.2V, UNIT:nA
VAUX = 0.6V, SAMPLING ENABLED,UNIT: nA
VAUX = 0.6V, SAMPLINGDISABLED, UNIT: nA
11891-018
0
1
2
3
4
5
6
7
8
9
10
11
12
11891-019
0 5 10 15 20 25
MAXI MUM ERROR (%)
CURRENT SENSE VOTLAGE (mV)
GRADE A, T
A
=−40°CTO +105°C
GRADE B, T
A
=−40°CTO +105°C
Rev. B | Page 12 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 13 of 48
Figure 20. VADRx vs. IADRx
Figure 21. GPOx Output Low Voltage vs. Sink Current
0
0.5
1.0
1.5
2.0
2.5
3.0
–25 –20 –15 –10 –5 0 5
V
ADRx
(V)
IADRx (µ A)
00 DECODE 01 DECODE 10 DECODE 11 DE CODE
11891-020
0
0.5
1.0
1.5
2.0
2.5
024681012
GPOx LOW VOLTAGE (V)
SI NK C URR ENT (mA)
GPO1
GPO2
11891-021
ADM1293/ADM1294 Data Sheet
THEORY OF OPERATION
POWERING THE ADM1293
A supply voltage from 2.95 V to 20 V is required to power the
ADM1293 via the VCC pin. The VCC pin provides the majority
of the bias current for the device.
To ensure correct operation of the ADM1293, the voltage on the
VCC pin must be greater than or equal to the voltage on the
SENSEP pin. No sequencing of the VCC and SENSEP rails is
necessary. The voltage on SENSEP pin can drop to as low as 0 V
for normal operation, provided that a voltage of at least 2.95 V
is connected to the VCC pin. For a monitoring supply rail above
3 V, connect both the VCC pin and the SENSEP pin to the same
voltage rail via separate traces to prevent accuracy loss in the
sense voltage measurement (see Figure 22).
Figure 22. Powering the ADM1293 from a Monitoring Rail
To protect the ADM1293 from unnecessary resets due to transient
supply glitches, add an external resistor, as shown in Figure 23.
Choose the values of the resistor in conjunction with the
decoupling capacitor such that a time constant is provided that can
filter any expected glitches. However, use a resistor that is small
enough to keep voltage drops due to quiescent current to a
minimum.
Figure 23. Transient Glitch Protection Using an RC Network
For monitoring rails below 2.95 V to 0 V, a separate supply is
required to provide power to the ADM1293, as shown in Figure 24.
Figure 24. Powering the ADM1293 from a Separate Supply
POWERING THE ADM1294
The internal shunt regulator allows ADM1294 to be powered
directly from a high voltage source. The shunt regulator is
disabled when the supply voltage on the VSHUNT pin is below
shunt regulation voltage level. After the supply rises above the
shunt regulation level, the shunt regulator starts to regulate the
voltage on the VSHUNT pin to approximately 12 V. An external
current limiting resistor is required to limit the current entering
the VSHUNT pin, as shown in Figure 25.
Figure 25. Powering the ADM1294 in a −48 V System
The shunt regulator also maintains a stable supply voltage
during transient events on the input supply, protecting the
ADM1294 from experiencing overvoltage stress.
Shunt Current Limiting Resistor Selection
The current limiting resistor value must be calculated correctly
to provide sufficient current/voltage to power the ADM1294,
while keeping the power low enough to prevent the IC from
overheating.
Calculate the current limiting resistance upper limit by
MAXCC4
MINOP4MININPUT
MAX
SHUNT
I
VV
R
_
__
_
–
=
where:
VINPUT_MIN is the minimum supply input voltage before the
current limiting resistor.
VOP4_MIN is the minimum operating voltage of the ADM1294.
ICC4_MAX is the maximum supply current of the ADM1294.
When the ADM1294 is in shunt regulation mode, if the supply
voltage decreases to a point where the current flowing through
the current limiting resistor is not enough to power the IC, the
ADM1294 automatically exits the fixed voltage regulation mode
and enters into current regulation mode. In current regulation
mode, the device lowers the voltage on the VSHUNT pin to
maintain the current required to power itself. The VSHUNT
pin voltage can be decreased to the minimum operating voltage
of the ADM1294. The smooth transition in and out of shunt
regulation mode helps to increase the RSHUNT_MAX value, and as a
result, extends the range of the suitable current limiting resistors.
SENSEP
VCC
SENSEN
12V
ADM1293
VIN
GND
0.1µF
R
SENSE
LOAD
11891-022
SENSEP
VCC
SENSEN
3.3V
22Ω
ADM1293
VIN
GND
0.1µF
R
SENSE
LOAD
11891-024
SENSEP
VCC
SENSEN
1V
3.3V
ADM1293
VIN
GND
R
SENSE
LOAD
0.1µF
11891-023
SENSEN
VEE
VSHUNT
SENSEP
RTN
–48V
ADM1294
VIN
LOAD
11891-025
RSENSE
RSHUNT
0.1µF
Rev. B | Page 14 of 48
Data Sheet ADM1293/ADM1294
Calculate the current limiting resistance lower limit by
MAXSHUNT
MAXSHUNTMAXINPUT
MINSHUNT
I
VV
R
_
__
_
–
=
where:
VINPUT_MAX is the maximum supply input voltage before the
current limiting resistor.
VSHUNT_MAX is the maximum shunt regulation voltage of the
ADM1294.
ISHUNT_MAX is the maximum current allowed into the shunt
regulator. It is related to the maximum allowable power
dissipation of the device in a given design, which is limited by
the maximum junction temperature of the device.
MAXSHUNT
MAXDISS
MAXSHUNT
V
P
I
_
_
_
=
and
JA
MAXAMAXJ
MAXDISS
TT
P
θ
__
_
–
=
where:
TJ_MAX is the maximum junction temperature of the ADM1294.
TA_MAX is the maximum ambient temperature of the system.
θJA is the junction to ambient thermal resistance of the ADM1294.
Example 1: A system has a −48 V supply that can vary between
−35 V to −75 V. The system maximum ambient temperature is
85°C. An ADM1294 in an LFCSP package monitors the supply.
It is soldered on a JEDEC 2S2P board, with a minimal footprint
and a 3 × 3 thermal via array.
Note that because the ADM1294 uses low-side sensing, as
shown in Figure 25, all of the voltages are expressed by
referencing to the negative supply input.
Ω=== k98
mA63
V952V35
4
4
.
.
.–
I
V–V
R
_MAXCC
_MINOPINPUT_MIN
SHUNT_MAX
W449.0
C58.50
C85–C110
–
_
=
°
°°
==
JA
AMAXJMAX
MAXDISS
TT
P
θ
mA83
V13
W494.0
_
_
_
===
MAXSHUNT
MAXDISS
MAXSHUNT
V
P
I
Ω=== k63.1
mA83
V13–V57
–
_
__
_
MAXSHUNT
MAXSHUNTMININPUT
MINSHUNT I
VV
R
The user can select a current limiting resistor with a value
between 8.9 kΩ and 1.63 kΩ. It is recommended to select one at
the higher end to reduce power dissipation. After a value is
chosen, for example, 7.5 kΩ, the user must check its worst-case
power dissipation. In this example, the worst case is when the
input supply is at its maximum value.
The worst case power dissipation across the current limiting
resistor is
( )
( )
W0.54
k7.5 V11.5–V75
–
2
2
__
=
Ω
=
=
SHUNT
MINSHUNTMAXINPUT
R_WORST R
VV
P
The user may need multiple resistors in series or in parallel to
meet the power level that is required.
Example 2: A system has a 180 V supply that can vary between
−160 V to +200 V. The system maximum ambient temperature
is 105°C. An ADM1294 in the LFCSP package monitors the supply.
It is soldered on a JEDEC 2S2P board, with a minimal footprint
and a 3 × 3 thermal via array.
Ω=== k6.43
mA63.
V95.2–V160
–
_
__
_
MAXCC4
MINOP4MININPUT
MAXSHUNT
I
VV
R
W1
.0
C58.50
C105
–C110
–
_
=
°
°°
==
JA
AMAXJMAX
MAXDISS
TT
P
θ
mA7.7
V13
W0.1
_
_
_
===
MAXSHUNT
MAXDISS
MAXSHUNT
V
P
I
Ω=== k3.24
mA7.7 V13–V200
–
_
__
_MAXSHUNT
MAXSHUNTMININPUT
MINSHUNT
I
VV
R
The user can select a current limiting resistor with a value between
43.6 kΩ and 24.3 kΩ. This example uses a 39 kΩ resistor.
The worst case power dissipation across the current limiting
resistor is:
( )
( )
W910.
k39 V11.5–V200
–
2
2
__
=
Ω
=
=
SHUNT
MINSHUNTMAXINPUT
R_WORST
R
VV
P
The user may need multiple resistors in series or in parallel to
meet the power level that is required.
Additional Options of Powering the ADM1294
If the supply input range is too wide to choose a suitable current
limiting resistor or causing too much power loss, a source follower
circuit can be used to generate the supply voltage for the
ADM1294, as shown in Figure 26.
Figure 26. Powering the ADM1294 Through a Source Follower Circuit
VSHUNT
VEE
VIN
ADM1294
0.1µF
5.6V
R
Z
R1
M1
11891-026
Rev. B | Page 15 of 48
ADM1293/ADM1294 Data Sheet
In this circuit, RZ limits the current into the Zener diode, the
NMOSFET (or an NPN transistor in the case of an emitter
follower) buffers the voltage created by the Zener to supply the
ADM1294. The NMOS must be able to withstand the voltage
drop of the supply voltage and the worst case power dissipation.
The worst case power dissipation is expressed as
PFET_WORST = (VINPUT_MAX − VZENER + VTH) × ICC4_MAX
where:
VINPUT_MAX is the maximum supply input voltage before the
current limiting resistor.
VZENER is the Zener diode reverse breakdown voltage.
VTH is the threshold of the NMOSFET or base to emitter voltage
in the case of an NPN emitter follower.
ICC4_MAX is the maximum supply current of the ADM1294.
Another option to supply power to the ADM1294 is to use the
ADM3260 I2C and a power isolator, as shown in Figure 27.
Figure 27. Powering the ADM1294 Using the ADM3260 I2C and Power
Isolator
Isolation is usually required in −48 V systems because there can
be a large voltage difference between different ground planes in
the system. The ADM1294 is referenced to −48 V, whereas the
microcontroller unit (MCU) is usually referenced to 0 V. In almost
all cases, the I2C signals must be isolated. Any other ADM1294
digital input and output signals that enter or exit the MCU must
also be isolated.
The ADM3260 isolator can transfer power and a bidirectional
I2C digital signal across an isolation barrier of up to 2.5 kV. The
output voltage from the ADM3260 can power the ADM1294
directly as well as providing pull-up resistance for the I2C bus
lines. See the ADM3260 data sheet for more information about
this device.
OPTIONAL POWER MONITOR INPUTS FILTERING
The internal ADC on both the ADM1293 and ADM1294 uses
the current sense input pins, SENSEP and SENSEN, to measure
the load current. Additional antialiasing filtering can be placed
on the power monitor pins to reduce current monitoring noise.
Similarly, RC filters can be used on the voltage sensing inputs,
VIN and VAUX, to reduce voltage sensing noise.
Figure 28. Power Monitor Input Filters for the ADM1293
Figure 29. Power Monitor Input Filters for the ADM1294
POWER MONITOR
The ADM1293/ADM1294 feature an integrated ADC that
accurately measures the current sense voltage, the input voltage,
and optionally, an auxiliary input voltage. The measured input
voltage, and current being delivered to the load are multiplied
together to give a power value that can be read back. Each power
value is also added to an energy accumulator that can be read
back to allow an external device to calculate the energy
consumption of the load.
The ADM1293/ADM1294 can report the measured current,
input voltage, and auxiliary voltage. The PEAK_VIN,
PEAK_VAUX, MIN_IOUT, MAX_IOUT, MIN_PIN, and
MAX_PIN commands are used to read the peak readings since
the value was last cleared.
An averaging function of up to 128× is provided for the voltage,
current, and power. This function allows a number of samples to
be averaged together by the ADM1293/ADM1294. This
function reduces the need for postprocessing of sampled data
by the host processor. The number of samples that can be
averaged is 2N, where N is in the range of 0 to 7.
The power averaging is calculated independently of voltage and
current averaging value to give the most accurate result. For
example, if the two consecutive voltage measurement results are
12.00 V and 12.08 V, and the corresponding current measurement
results are 10.0 A and 10.8 A, and the 2× averaging results for
voltage and current are 12.04 V and 10.4 A, respectively, then
the 2× power averaging result is
W232.125
28.1008.121012 =
×+×
Not 12.04 × 10.4 = 125.216 W.
3.3V/5V
3.3V/5V_ISO
PROCESSOR
–48V
RTN
ADM3260
POWER + I
2
C
ISOLATOR
SDA
SCL
VINVISO
VSHUNT
VEE
SCL
SDAI
SDAO
SCL2
GNDP
SDA2
SCL1
GNDISO
SDA1
ADM1294
11891-027
SENSEP SENSEN
12V
3.3V
ADM1293
VIN VAUX
RSENSE
11891-028
SENSEN SENSEP
–48V
–48V
RTN 3.3V
(REFERENCE TO –48V )
ADM1294
VIN VAUX
RSENSE
11891-029
Rev. B | Page 16 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 17 of 48
The power monitor current sense amplifier is bipolar and can
measure both positive and negative currents. The current sense
amplifier has four selectable input ranges: ±25 mV, ±50 mV,
±100 mV, and ±200 mV. Operating closer to the full range
results in higher current measurement accuracy and higher
insertion loss across the sense resistor.
The power monitor voltage sensing input, VIN, has three
selectable input ranges: 0 V to 1.2 V, 0 V to 7.6 V, and 0 V to
21 V. Configuring the VIN pin to the 0 V to 1.2 V range gives
the pin a direct connection to the internal ADC, and results in
minimum leakage current into the pin. It is the recommended
configuration for use with external resistor dividers. The VAUX
input has a fixed 0 V to 1.2 V voltage monitoring range. Both
the current and voltage sensing ranges can be configured using
the PMON_CONFIG command.
The two basic modes of operation for the power monitor are
single shot and continuous. In single shot mode, the ADC samples
the input voltage and current a number of times, depending on
the averaging value selected by the user. The ADM1293/ADM1294
return a single value corresponding to the average voltage and
current measured. When configured for continuous mode, the
power monitor continuously samples the voltage and current,
making the most recent sample available to be read.
Single shot mode can be triggered in a number of ways.
The simplest is by selecting the single shot mode using the
PMON_CONFIG command and writing to the convert bit
using the PMON_CONTROL command. The convert bit can
also be written as part of a PMBus group command. Using a
group command allows multiple devices to be written to as part
of the same I2C bus transaction, with all devices executing the
command when the stop condition appears on the bus. In this
way, several devices can be triggered to sample at the same time.
When the GPO1/ALERT1/CONV pin is set to convert (CONV)
mode, an external hardware signal triggers the single shot
sampling of one or more parts at the same time.
Each time that current sense and input voltage measurements
are taken, a power calculation is performed that multiplies the
two measurements together. This can be read from the device
using the READ_PIN command, returning the input power.
At the same time, the calculated power value is added to the power
accumulator register that may increment a rollover counter if
the value exceeds the maximum accumulator value. The power
accumulator register also increments a power sample counter.
The power accumulator and power sample counter are read using
the same READ_EIN command to ensure that the accumulated
value and sample count are from the same point in time. The
bus host reading the data assigns a time stamp when the data is
read. By calculating the time difference between consecutive uses
of READ_EIN and determining the delta in power consumed, it
is possible for the host to determine the total energy consumed
over that period.
Table 7. ADM1293 and ADM1294 Model Options
Model Build in Shunt Regulator Monitoring Accuracy Grade Energy Meter Implementation
ADM1293-1A No A Custom
ADM1293-1B No B Custom
ADM1294-1A Yes A Custom
ADM1294-1B Yes B Custom
ADM1293-2A No A PMBus Standard
ADM1294-2A Yes A PMBus Standard
ADM1293/ADM1294 Data Sheet
PMBus INTERFACE
The I2C bus is a common, simple serial bus used by many devices
to communicate. It defines the electrical specifications, the bus
timing, the physical layer, and some basic protocol rules.
SMBus is based on I2C and aims to provide a more robust and
fault tolerant bus. Functions such as bus timeout and packet
error checking are added to help achieve this robustness, along
with more specific definitions of the bus messages that read and
write data to devices on the bus.
PMBus is layered on top of SMBus and, in turn, on I2C. Using the
SMBus defined bus messages, PMBus defines a set of standard
commands that control a device that is part of a power chain.
The ADM1293/ADM1294 command set is based upon the
PMBus™ Power System Management Protocol Specification, Part I
and Part II, Revision 1.2. This version of the standard is
provides a common set of commands for communicating with
dc-to-dc type devices. However, many of the standard PMBus
commands can be mapped directly to the functions of a digital
power monitor.
Part I and Part II of the PMBus standard describe the basic
commands and how they are used in a typical PMBus setup.
The following sections describe how the PMBus standard and
the ADM1293/ADM1294 specific commands are used.
DEVICE ADDRESSING
The PMBus device address is seven bits in size. There are no
default addresses for any of the models; any device can be
programmed to any of 16 possible addresses. Two quad level
ADRx pins map to the 16 possible device addresses.
Table 8. ADRx Pin Connections
ADRx State ADRx Pin Connection
Low Connect to GND
Resistor 150 kΩ resistor to GND
High-Z No connection (floating)
High
Connect to VCAP
Table 9. Setting I2C Addresses via the ADR1 Pin and the ADR2 Pin
Base Address
(Binary) ADR2 Pin State ADR1 Pin State ADR2 Logic State ADR1 Logic State Address (Binary)1 Address (Hex)
011
Ground
Ground
00
00
0110000X
0x30
Ground Resistor to ground 00 01 0110001X 0x31
Ground Floating 00 10 0110010X 0x32
Ground High 00 11 0110011X 0x33
Resistor to ground Ground 01 00 0110100X 0x34
Resistor to ground Resistor to ground 01 01 0110101X 0x35
Resistor to ground Floating 01 10 0110110X 0x36
Resistor to ground High 01 11 0110111X 0x37
Floating Ground 10 00 0111000X 0x38
Floating Resistor to ground 10 01 0111001X 0x39
Floating Floating 10 10 0111010X 0x3A
Floating High 10 11 0111011X 0x3B
High
Ground
11
00
0111100X
0x3C
High Resistor to ground 11 01 0111101X 0x3D
High Floating 11 10 0111110X 0x3E
High High 11 11 0111111X 0x3F
1 X means don’t care.
Rev. B | Page 18 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 19 of 48
SMBus PROTOCOL USAGE
All I2C transactions on the ADM1293/ADM1294 are performed
using SMBus defined bus protocols. The following SMBus
protocols are implemented by the ADM1293/ADM1294:
Send byte
Receive byte
Write byte
Read byte
Write word
Read word
Block read
PACKET ERROR CHECKING
The ADM1293/ADM1294 PMBus interface supports the use
of the packet error checking (PEC) byte, which is defined in the
SMBus standard. The PEC byte is transmitted by the ADM1293/
ADM1294 during a read transaction or sent by the bus host
to the ADM1293/ADM1294 during a write transaction. The
ADM1293/ADM1294 support the use of PEC with all the
SMBus protocols that it implements.
The use of the PEC byte is optional. The bus host can decide
whether to use the PEC byte with the ADM1293/ADM1294 on
a message by message basis. There is no need to enable or
disable PEC in the ADM1293/ADM1294.
The PEC byte is used by the bus host or the ADM1293/ADM1294
to detect errors during a bus transaction, depending on whether
the transaction is a read or a write. If the host determines that
the PEC byte read during a read transaction is incorrect, it can
decide to repeat the read if necessary. If the ADM1293/ADM1294
determine that the PEC byte sent during a write transaction is
incorrect, it ignores the command (does not execute it) and sets
a status flag.
Within a group command, the host can choose whether to send
a PEC byte as part of the message to the ADM1293/ADM1294.
PARTIAL TRANSACTIONS ON I2C BUS
If there is a partial transaction on the I2C bus, for example,
spurious data interpreted as a start command, the ADM1293/
ADM1294 I2C bus does not lock up, thinking it is in the middle
of an I2C transaction. A new start command is recognized even
in the middle of another transaction.
SMBus MESSAGE FORMATS
Figure 30 to Figure 38 show all of the SMBus protocols that are
supported by the ADM1293/ADM1294, together with the PEC
variant. In these figures, unshaded cells indicate that the bus
host is actively driving the bus; shaded cells indicate that the
ADM1293/ADM1294 is driving the bus.
Figure 30 to Figure 38 use the following abbreviations:
S is the start condition.
Sr is the repeated start condition.
P is the stop condition.
R is the read bit.
W is the write bit.
A is the acknowledge bit (0).
A is the acknowledge bit (1).
A, the acknowledge bit, is typically active low (Logic 0) if the
transmitted byte is successfully received by a device. However,
when the receiving device is the bus master, the acknowledge bit
for the last byte read is a Logic 1, indicated by A.
Figure 30. Send Byte and Send Byte with PEC
Figure 31. Receive Byte and Receive Byte with PEC
Figure 32. Write Byte and Write Byte with PEC
SPAAWSLAVE ADDRESS DATA BYTE
S PAAWSLAVE ADDRESS DATA BYTE PEC A
MASTER TO SLAVE
SLAVE TO MASTER
11891-030
SPAARSLAVE ADDRES S DATA BYT E
S PAARSLAVE ADDRES S DATA BYT E PEC
MASTER TO SLAVE
SLAVE TO MASTER
A
11891-031
SAAWSLAVE ADDRESS COMM AND CODE DATA BYT E PA
SAAWSLAVE ADDRESS COMM AND CODE DATA BYTE PA PEC A
MASTER TO SLAVE
SLAVE TO MASTER
11891-032
ADM1293/ADM1294 Data Sheet
Rev. B | Page 20 of 48
Figure 33. Read Byte and Read Byte with PEC
Figure 34. Write Word and Write Word with PEC
Figure 35. Read Word and Read Word with PEC
Figure 36. Block Read and Block Read with PEC
Figure 37. Group Command
Figure 38. Group Command with PEC
A
SLAVE ADDRESS RDATA BYTE
Sr A
A
SA
AWSLAVE ADDRES S COM MAND CODE PA
PEC
SAAWS LAVE ADDRES S CO MM AND CO DE SLAVE ADDRESS PRDATA BYTE
Sr A
MASTER TO SLAVE
SLAVE TO MASTER
11891-033
P
SAAWSLAVE ADDRESS CO MM AND CO D E DATA BYTE L O W A A
SAAWSLAVE ADDRESS CO MM AND CO D E DATA BYTE L O W A D ATA BYT E HI G H
DATA BYTE HI GH
APA
PEC
MASTER TO SLAVE
SLAVE TO MASTER
11891-034
SrA SLAVE ADDRESS ARSAWSLAVE ADDRES S COMMAND CODE ADATA BYTE LOW
PA
AA
DATA BYT E HI GH
SrA SLAVE ADDRESS ARSAWSLAVE ADDRES S COMMAND CODE ADATA BYTE LOW
DATA BYT E HI GH P
PEC
MASTER TO SLAVE
SLAVE TO MASTER
11891-035
SrA SLAVE ADDRESS ARSAWSLAVE ADDRESS CO M M AND CODE ABYTE COUNT = N
A
DATA BYTE 1 PDATA BYTE NA
DATA BYTE 2
SrA SLAVE ADDRESS ARSAWSLAVE ADDRESS CO M M AND CODE ABYTE COUNT = N
A
DATA BYTE 1 ADATA BYTE N PPECA
DATA BYTE 2
MASTER TO SLAVE
SLAVE TO MASTER
A
A
11891-036
MASTER TO SLAV E
SLAVE TO MASTER
ALOW DATA BYTEASAWDEVICE 1 ADDRESS COMMAND CO DE 1 AHIGH DATA BYTE
ONE OR MORE DATA BYTES
ALOW DATA BYTEASr AWDEVICE 2 ADDRESS COMM AND CO DE 2 AHIGH DATA BYTE
ONE OR MORE DATA BYTES
ALOW DATA BYTEASr AWDEVICE N ADDRESS COMMAND CODE N APHIG H DATA BYTE
ONE OR MORE DATA BYTES
11891-037
MASTER TO SLAVE
SLAVE TO M AST ER
APEC 1
P
ALOW DATA BYTEASAWDEVICE 1 ADDRESS COMMAND CODE 1 AHIGH DATA BYTE
ONE OR MORE DATA BYTES
APEC 2
ALOW DATA BYTEASr AWDEVICE 2 ADDRESS COMMAND CODE 2 AHIGH DATA BYTE
ONE OR MORE DATA BYTES
A
PEC N
ALOW DATA BYTEASr AWDEVICE N ADDRESS COMMAN D CODE N AHIG H DATA BYTE
ONE OR MORE DATA BYTES
11891-038
Data Sheet ADM1293/ADM1294
GROUP COMMANDS
The PMBus standard defines what are known as group commands.
Group commands are single bus transactions that send commands
or data to more than one device at the same time. Each device is
addressed separately, using its own address; there is no special
group command address. A group command transaction can
contain only write commands that send data to a device. It is
not possible to use a group command to read data from devices.
From an I2C protocol point of view, a normal write command
consists of the following:
• I2C start condition
• Slave address bits and a write bit (followed by an
acknowledge from the slave device)
• One or more data bytes (each of which is followed by an
acknowledge from the slave device)
• I2C stop condition to end the transaction
A group command differs from a nongroup command in that
after the data is written to one slave device, a repeated start
condition is placed on the bus, followed by the address of the
next slave device and data. This continues until all of the
devices have been written to, at which point the stop condition
is placed on the bus by the master device.
The format of a group command and a group command with
PEC is shown in Figure 37 and Figure 38.
Each device that is written to as part of the group command
does not immediately execute the command written. The device
must wait until the stop condition appears on the bus. At that
point, all devices execute their commands at the same time.
Using a group command, it is possible, for example, to turn
multiple PMBus devices on or off simultaneously. In the case of
the ADM1293/ADM1294, it is also possible to issue a power
monitor command that initiates a conversion, causing multiple
ADM1293/ADM1294 devices to sample together at the same time.
INFORMATION COMMANDS
CAPABILITY Command
Host processors can use the CAPABILITY command to
determine the I2C bus features that are supported by the
ADM1293/ADM1294. The features that can be reported
include the maximum bus speed, whether the device supports
the PEC byte, and the SMBALERT reporting function.
PMBUS_REVISION Command
The PMBUS_REVISION command reports the version of Part I
and Part II of the PMBus standard.
MFR_ID, MFR_MODEL, and MFR_REVISION Commands
The MFR_ID, MFR_MODEL, and MFR_REVISION commands
return ASCII strings that facilitate detection and identification
of the ADM1293/ADM1294 on the bus.
These commands are read using the SMBus block read message
type. This message type requires that the ADM1293/ADM1294
return a byte count corresponding to the length of the string
data that is to be read back.
STATUS COMMANDS
The ADM1293/ADM1294 provide a number of status bits that
are used to report warnings detected. These status bits are located
in four different registers that are arranged in a hierarchy. The
STATUS_BYTE and STATUS_WORD commands provide
8 bits and 16 bits of high level information, respectively. The
STATUS_BYTE and STATUS_WORD commands contain the
most important status bits, as well as pointer bits that indicate
whether any of the three other status registers must be read for
more detailed status information.
Warnings in the ADM1293/ADM1294 are generated from a
digital comparison between the power monitor measurements
to the threshold values set by the various limit commands. A
warning can be used to control the state of the ALERTx output
pins, or to generate a SMBALERT interrupt signal through one
of the ALERTx pins.
When a status bit is set, it always means that the status condition is
active or was active at some point in the past. When a warning bit
is set, it is latched until it is explicitly cleared using the
CLEAR_FAULTS command. Some other status bits are live, that
is, they always reflect a status condition and are never latched.
STATUS_BYTE and STATUS_WORD Commands
The STATUS_BYTE and STATUS_WORD commands can
be used to obtain a snapshot of the overall device status. These
commands indicate whether it is necessary to read more
detailed information using the other status commands.
The low byte of the word returned by the STATUS_WORD
command is the same byte returned by the STATUS_BYTE
command. The high byte of the word returned by the
STATUS_WORD command provides a number of bits that
can be used to determine which of the other status commands
must be issued to obtain all active status bits.
STATUS_INPUT Command
The STATUS_INPUT command returns a number of bits
relating to voltage warnings on the VIN pin as well as the
overpower warning.
STATUS_IOUT Command
The STATUS_IOUT command returns a number of bits
relating to current warnings on the monitoring rail.
STATUS_MFR_SPECIFIC Command
The STATUS_MFR_SPECIFIC command is a standard PMBus
command, but the contents of the byte returned are specific to
the ADM1293/ADM1294. It returns a number of bits relating to
voltage warnings on the VAUX pin.
Rev. B | Page 21 of 48
ADM1293/ADM1294 Data Sheet
CLEAR_FAULTS Command
The CLEAR_FAULTS command clears warnings bits when they
are set. Warning bits are latched when they are set. In this way, a
host can read the bits any time after the warning condition
occurs and determine which problem actually occurred.
If the CLEAR_FAULTS command is issued and the warning
condition is no longer active, the status bit is cleared. If the
condition is still active—for example, if the input voltage
is below the undervoltage threshold of the VIN pin—the
CLEAR_FAULTS command attempts to clear the status bit, but
that status bit is immediately set again.
GPOX AND ALERTx PIN SETUP COMMANDS
Two multipurpose pins are provided on the ADM1293/
ADM1294: GPO1/ALERT1/CONV and GPO2/ALERT2.
These pins can be configured over the PMBus in one of three
output modes, as follows:
• General-purpose digital output
• Output for generating an SMBALERT when one or more
warning status bits become active in the PMBus status
registers
• Digital comparator
In digital comparator mode, the current, voltage, and power
warning thresholds are compared to the values read or calculated
by the ADM1293/ADM1294. The comparison result sets the
output high or low according to whether the value is greater or
less than the warning threshold that has been set.
For an example of how to configure these pins to generate an
SMBALERT and how to respond and clear the condition, see
the Example Use of SMBus ARA section.
ALERT1_CONFIG and ALERT2_CONFIG Commands
Using combinations of bit masks, the ALERT1_CONFIG and
ALERT2_CONFIG commands select the status bits that, when
set, generate an SMBALERT signal to a processor, or control the
digital comparator mode. The GPO1/ALERT1/CONV and
GPO2/ALERT2 pins must be configured in SMBALERT or
digital comparator mode in the DEVICE_CONFIG register.
If configured in GPO mode, the pin is under software control. If
this mode is set, the SMBALERT masking bits are ignored.
POWER MONITOR COMMANDS
The ADM1293/ADM1294 provide a high accuracy, 12-bit
current, voltage, and power monitor. The power monitor can be
configured in a number of different modes of operation and can
run in either continuous mode or single shot mode with a
number of different sample averaging options.
The power monitor can measure the following quantities:
• Input voltage (VIN)
• Output current (IOUT)
• Auxiliary input voltage (VAUX)
The following quantities are then calculated:
• Input power (PIN)
• Energy flow in forward direction (EIN)
• Energy flow in reverse direction (EOUT)
PMON_CONFIG Command
The power monitor can run in a number of different modes. The
PMON_CONFIG command is used to set up the power
monitor.
The settings that can be configured are as follows:
• Single shot or continuous sampling
• VIN/VAUX sampling enable/disable
• Current and voltage sample averaging
• Power sample averaging
• Simultaneous sampling enable/disable
• VIN monitoring range selection
• Current monitoring range selection
Modifying the power monitor settings while the power monitor
is sampling is not recommended. To ensure correct operation of
the device and to avoid any potential spurious data or the
generation of status alerts, stop the power monitor before
changing any of these settings.
PMON_CONTROL Command
Power monitor sampling can be initiated via hardware or via
software using the PMON_CONTROL command. This command
can be used with single shot or continuous mode.
READ_VIN, READ_VAUX, and READ_IOUT Commands
The ADM1293/ADM1294 power monitor always measures the
voltage developed across the sense resistor to provide a current
measurement. ADM1293/ADM1294 supports bidirectional
current monitoring and the data returned by the READ_IOUT
command is expressed in twos complement format with the
MSB indicating the direction of the current flow. A MSB of 0
indicates positive current flow (from the SENSEP pin to the
SENSEN pin), and a MSB of 1 indicates reverse current flow
(from the SENSEN pin to the SENSEP pin).
The input voltage measurement from the SENSEP pin is also
enabled by default. The auxiliary input voltage present on the
VAU X pin is available if enabled with the PMON_CONFIG
command.
READ_PIN, READ_PIN_EXT, READ_EIN, and
READ_EIN_EXT Commands
The 12-bit VIN input voltage and 12-bit IOUT current measure-
ment values are multiplied by the ADM1293/ADM1294 to give
the input power value. This is accomplished by using fixed point
arithmetic, and produces a 24-bit value. It is assumed that the
numbers are in the 12.0 format, meaning that there is no
fractional part.
This 24-bit extended precision power value can be read from
the ADM1293/ADM1294 using the READ_PIN_EXT command.
Rev. B | Page 22 of 48
Data Sheet ADM1293/ADM1294
The 16 most significant bits of the 24-bit value can be read
using the READ_PIN command.
Similar to READ_IOUT, both the READ_PIN and the
READ_PIN_EXT commands are expressed in twos
complement format with the MSB indicating the direction of
the power flow.
READ_EIN, READ_EIN_EXT, READ_EOUT, and
READ_EOUT_EXT Commands
There are two sets of power accumulators inside the
ADM1293/ADM1294 to support bidirectional energy metering
function.
The forward flowing power data (from the SENSEP pin to the
SENSEN pin, with an MSB of 0) is accumulated in the
READ_EIN register and the negative flowing power data (from
the SENSEN pin to the SENSEP pin, with an MSB of 1) is
accumulated in the READ_EOUT register.
Each time a power calculation is performed, the 24-bit power
value is added to a corresponding unsigned 24-bit energy
accumulator register.
Each time this energy accumulator register rolls over from
0xFFFFFF to 0x000000, a 16-bit rollover counter is incremented.
The rollover counter is straight binary, with a maximum value
of 0xFFFF before it rolls over.
A 24-bit straight binary power sample counter is also
incremented by 1 each time a power value is calculated and
added to the energy accumulator.
These registers can be read back either in standard data format
by the READ_EIN and the READ_EOUT commands, or
extended precision data format by the READ_EIN_EXT and
the READ_EOUT_EXT commands, depending on the level of
accuracy required for the energy accumulator and the desire to
limit the frequency of reads from the ADM1293/ADM1294.
A bus host can read these values, and by calculating the delta in
the power accumulated, the delta in the number of samples, and
the time delta since the last read, the host can calculate the
average power since the last read, as well as the energy
consumed since the last read.
The time delta is calculated by the bus host based on when it
sends its commands to read from the device, and is not
provided by the ADM1293/ADM1294.
To avoid data loss, the bus host must read at a rate that ensures
the rollover counter does not wrap around more than once, and
if the counter does wrap around, that the next value read for PIN
is less than the previous one.
The READ_EIN and READ_EOUT commands return the top
16 bits of the energy accumulator, the lower 8 bits of the
rollover counter, and the full 24 bits of the sample counter.
The READ_EIN_EXT and READ_EOUT_EXT commands
return the full 24 bits of the energy accumulator, the full 16 bits
of the rollover counter, and the full 24 bits of the sample
counter. The use of the longer rollover counter means that the
time interval between reads of the device can be increased from
seconds to minutes, without losing any data.
By disabling VIN sampling, a constant value of 1 is assigned to
the VIN register. This allows IOUT data to be duplicated in the
PIN register, as PIN = IOUT × 1 = IOUT and transforms the
power accumulators to current accumulators/coulomb counters.
READ_EIN and READ_EOUT Commands in the PMBus
Standard
The definition and implementation of the READ_EIN and
READ_EOUT commands on the ADM1293/ADM1294 devices
are slightly different from the ones described in the PMBus
Standard. Pay special attention to the differences to avoid a
calculation error.
In terms of the definition, the READ_EIN and READ_EOUT
commands described in the PMBus standard are used to return
the accumulated power values entering and then exiting the
PMBus device. Together they allow the host to calculate the
power and energy consumption of the PMBus device. This is
useful for devices with dynamic power loss such as a dc-to-dc
converter.
As dedicated power monitors, the power consumption of the
ADM1293/ADM1294 devices is fairly constant and generally
very small compared to the power they are trying to monitor.
Therefore, instead of monitoring their own power consumption,
the READ_EIN and READ_EOUT commands on the
ADM1293/ADM1294 are designed to return the accumulated
bidirectional power data on the monitored supply rail. They
allow the user to calculate the energy flow on the rail in both
directions.
As for implementation, the power accumulation data described
in the PMBus standard are expressed in signed, 16-bit, twos
complement format. The rollover counter increases by 1 each
time the energy accumulator register rolls over from 0x7FFF to
0x0000.
The power accumulators on the ADM1293/ADM1294 devices are
defined to accumulate power in one specific direction. This
removes the need for the sign bit and the power accumulation
data on the ADM1293/ADM1294 devices is expressed as an
unsigned 16-bit value. As a result, the rollover counter increases
by 1 each time the energy accumulator register rolls over from
0xFFFF to 0x0000.
Rev. B | Page 23 of 48
ADM1293/ADM1294 Data Sheet
PEAK_VIN, PEAK_VAUX, MIN_IOUT, MAX_IOUT,
MIN_PIN, and MAX_PIN Commands
In addition to the standard PMBus commands for reading
voltage, current, and power, the ADM1293/ADM1294 provide
commands that report the maximum peak voltage, the
maximum and minimum current, and the power values recorded.
The ADM1293/ADM1294 devices support bidirectional current
and power monitoring. Both current and power data are
expressed in twos complement format with the MSB being the
sign bit indicating the direction of the current/power flow. For
current and power, the maximum values are defined as the most
positive values recorded (flowing from the SENSEP pin to the
SENSEN pin) or least negative values recorded (flowing from
the SENSEN pin to the SENSEP pin), and the minimum values
are defined as the most negative or least positive values
recorded. For example, if the current readback ranges between 3
A and 5 A, the MAX_IOUT command returns 5 A and the
MIN_IOUT command returns 3 A. If the current readback
ranges between −3 A and −5 A, the MAX_IOUT command
returns −3 A and the MIN_IOUT command returns −5 A.
Theses peak values are updated only after the power monitor
has sampled and averaged the current and voltage measurements.
Individual peak values are cleared by writing a value of 0 with
the corresponding command.
WARNING LIMIT SETUP COMMANDS
The ADM1293/ADM1294 power monitor can monitor a
number of different warning conditions simultaneously and
report any current, voltage, or power values that exceed the user
defined thresholds using the status commands.
All comparisons performed by the power monitor require the
measured value to be strictly greater or less than the threshold
value.
At power-up, all threshold limits are set to either minimum
scale (for undervoltage conditions) or to maximum scale (for
overvoltage, overcurrent, or overpower conditions). This
effectively disables the generation of any status warnings by
default; warning bits are not set in the status registers until the
user explicitly sets the threshold values.
VIN_OV_WARN_LIMIT and VIN_UV_WARN_LIMIT
Commands
The VIN_OV_WARN_LIMIT and VIN_UV_WARN_LIMIT
commands set the overvoltage (OV) and undervoltage (UV)
thresholds on the input voltage, as measured at the VIN pin.
VAUX_OV_WARN_LIMIT and VAUX_UV_WARN_LIMIT
Commands
The VAU X _OV_WARN_LIMIT and VAU X _UV_WARN_
LIMIT commands set the OV and UV thresholds
on the output voltage, as measured at the VAUX pin.
IOUT_OC_WARN_LIMIT Command
The IOUT_OC_WARN_LIMIT command sets the overcurrent
threshold for the current flowing through the sense resistor.
If the threshold is a positive value, a more positive current
measurement value is required to trigger the overcurrent
warning. If the threshold is a negative value, a more negative
current measurement value is required to trigger the
overcurrent warning.
PIN_OP_WARN_LIMIT Command
The PIN_OP_WARN_LIMIT command sets the overpower
threshold for the power that appears on the rail being monitored.
If the threshold is a positive value, a more positive power meas-
urement value is required to trigger the overpower warning. If the
threshold is a negative value, a more negative power measurement
value is required to trigger the overpower warning.
PMBus DIRECT FORMAT CONVERSION
The ADM1293/ADM1294 uses the PMBus direct format to
represent real-world quantities such as voltage, current, and
power values. A direct format number takes the form of a 2-byte,
twos complement, binary integer value.
It is possible to convert between direct format value and real-
world quantities using the following equations. Equation 1 converts
from real-world quantities to PMBus direct values, and Equation 2
converts PMBus direct format values to real-world values.
Y = (mX + b) × 10R (1)
X = 1/m × (Y × 10−R − b) (2)
where:
Y is the value in PMBus direct format.
X is the real-world value.
m is the slope coefficient, a 2-byte, twos complement integer.
b is the offset, a 2-byte, twos complement integer.
R is a scaling exponent, a 1-byte, twos complement integer.
The same equations are used for voltage, current, and power
conversions (with the exception of accumulated power conversion),
the only difference being the values of the m, b, and R coefficients
that are used. Table 10 lists all the coefficients required for the
ADM1293/ADM1294. The current and power coefficients shown
are dependent on the value of the external sense resistor used in
a given application. This means that an additional calculation
must be performed to take the sense resistor value into account to
obtain the coefficients for a specific sense resistor value.
Rev. B | Page 24 of 48
Data Sheet ADM1293/ADM1294
Table 10. PMBus Conversion to Real-World Coefficients
Coefficients Voltage Range (V)1 Current Sense Range (mV)1 m2 b R
Voltage (V) 0 to 1.2 N/A 3333 −1 0
0 to 7.4 N/A 5552 −5 −1
0 to 21 N/A 19,604 −50 −2
Current (A) N/A ±25 8000 × RSENSE −100 −2
N/A ±50 4000 × RSENSE −100 −2
N/A ±100 20,000 × RSENSE −1000 −3
N/A ±200 10,000 × RSENSE −1000 −3
Power (W) 0 to 1.2 ±25 10,417 × RSENSE 0 −1
0 to 1.2 ±50 5208 × RSENSE 0 −1
0 to 1.2
±100
26,042 × R
SENSE
0
−2
0 to 1.2 ±200 13,021 × RSENSE 0 −2
0 to 7.4 ±25 17,351 × RSENSE 0 −2
0 to 7.4 ±50 8676 × RSENSE 0 −2
0 to 7.4 ±100 4338 × RSENSE 0 −2
0 to 7.4 ±200 21,689 × RSENSE 0 −3
0 to 21 ±25 6126 × RSENSE 0 −2
0 to 21 ±50 30,631 × RSENSE 0 −3
0 to 21 ±100 15,316 × RSENSE 0 −3
0 to 21 ±200 7658 × RSENSE 0 −3
1 N/A means not applicable.
2 The sense resistor value, used in the calculations to obtain the coefficients, is expressed in milliohms.
The sense resistor value used in the calculations to obtain the
coefficients is expressed in milliohms. The m coefficients are
defined as 2-byte twos complement numbers in the PMBus
standard; therefore, the maximum positive value that can be
represented is 32,767. If the m value is greater than that, and is
to be stored in PMBus standard form, then divide the m
coefficients by 10, and increase the R coefficient by a value of 1.
For example, if a 10 mΩ sense resistor is used, the m coefficient
for power is 6123, and the R coefficient is −1.
Example 1: IOUT_OC_WARN_LIMIT requires a current-limit
value expressed in direct format.
Assume the current sense range is 25 mV. If the required
current limit is 10 A and the sense resistor is 2 mΩ, the first step
is to determine the voltage coefficient. This is m = 8000 × 2,
giving 16,000.
Using Equation 1, and expressing X in units of amperes,
Y = ((16,000 × 10) –100) × 10−2
Y = 1599
Writing a value of 1599 with the IOUT_OC_WARN_LIMIT
command sets an overcurrent warning at 10 A.
Example 2: IOUT_OC_WARN_LIMIT requires a current-limit
value expressed in direct format.
Assume the current sense range is 25 mV. If the required
current limit is −10 A and the sense resistor is 2 mΩ, the first
step is to determine the voltage coefficient. This is m = 8000 ×
2, giving 16,000.
Using Equation 1, and expressing X in units of amperes,
Y = ((16,000 × −10) –100) × 10−2
Y = −1601 = (signed 16 bits) 0xF9BF? = (unsigned) 63935d
Writing a value of 63935d with the IOUT_OC_WARN_LIMIT
command sets an overcurrent warning at −10 A.
Example 3: the READ_IOUT command returns a direct format
value of 125, representing the current flowing through a sense
resistor of 1 mΩ. The current sense range is 50 m V.
To convert this value to the current flowing, use Equation 2, with
m = 4000 × 1.
X = 1/4000 × (125 × 102 + 100)
X = 3.15 A
This means that when READ_IOUT returns a value of 125,
3.15 A is flowing in the sense resistor. A positive values means
the current is flowing in the forward direction from the
SENSEP pin to the SENSEN pin.
Example 4: the READ_PIN command returns a direct format
value of 12,635, representing the power measured through a
sense resistor of 0.25 mΩ. The voltage range is 0 V to 21 V and
the current sense range is 0 mV to 25 m V.
To convert this value to the current flowing, use Equation 2, with
m = 6126 × 0.25 = 1531.5
X = 1/1531.5 × (12635 × 102 − 0)
X = 825 W
This means that, when READ_PIN returns a value of 12,635,
825 W is being delivered on the rail.
Rev. B | Page 25 of 48
ADM1293/ADM1294 Data Sheet
Note that the READ_PIN_EXT command returns the 24-bit
extended precision versions of the 16-bit values returned by the
READ_PIN command. The direct format values must be
divided by 256 before being converted with the coefficients
shown in Table 10.
ENERGY METER VALUE CONVERSION
On the ADM1293 and ADM1294, the accumulated power value
in the energy metering registers is stored as an unsigned integer.
The total energy accumulated can be derived by treating the
rollover count value as the most significant extension to the
power accumulator value.
Example 1: The READ_EIN command has been issued to an
ADM1293 or ADM1294 device twice by a processor with
1000 ms in between reads.
The data returned from the first read is
• SAMPLE_COUNT: 0x004000
• EIN_ROLLOVER_COUNT: 0x1A
• EIN_ENERGY_COUNT: 0x02FE
The data returned from the second read is
• SAMPLE_COUNT: 0x00602C
• EIN_ROLLOVER_COUNT: 0xF8
• EIN_ENERGY_COUNT: 0x2FDC
The sense resistor is 0.25 mΩ, the voltage range is 0 V to 21 V,
and the current sense range is 0 mV to 25 m V. Assuming the
rollover counter did not roll over between the two reads, the
processor is required to determine the energy consumption on
the rail being monitored during this time.
Start by determining the total power accumulated in the energy
meter register at each read. By treating the rollover count value
as the most significant extension to the power accumulator
value, the total power accumulated at the first read is 0x1A02FE.
Similarly, the total power accumulated at the second read is
0xF82FDC. The power delta between the two reads is
0xF82FDC − 0x1A02FE = 0xDE2CDE
And the sample count delta is
0x00602C − 0x004000 = 0x202C
The average power per sample between the two reads is
0xDE2CDE∕0x202C = 0x6E7 = 1767d
To convert this to a real-world value, the first step is to
determine the m coefficient, that is, m = 6126 × 0.25 = 1531.5.
Using Equation 2
X = 1/1531.5 × (1767 × 102 − 0)
X = 115.38 W
The energy consumed between the two reads is equal to the
average power by time.
Energy = 115.38 W × 1 sec = 115.38 J
On the ADM1293-2 and ADM1294-2, the accumulated power
value in the energy metering registers is presented in twos
complement format as defined in the PMBus standard.
Example 2: The READ_EIN command has been issued to an
ADM1293-2 or ADM1294-2 device twice by a processor with
1000 ms in between reads.
The data returned from the first read is
• SAMPLE_COUNT: 0x004000
• EIN_ROLLOVER_COUNT: 0x1A
• EIN_ENERGY_COUNT: 0x02FE
The data returned from the second read is
• SAMPLE_COUNT: 0x00602C
• EIN_ROLLOVER_COUNT: 0xF8
• EIN_ENERGY_COUNT: 0x2FDC
The sense resistor is 0.25 mΩ, the voltage range is 0 V to 21 V,
and the current sense range is 0 mV to 25 mV. Assuming the
rollover counter did not roll over between the two reads, the
processor is required to determine the energy consumption on
the rail being monitored during this time.
Start by determining the total power accumulated in the energy
meter register at each read.
Total Power = RolloverCount × MaximumEnergyCount +
EnergyCount
Where the maximum energy count is the maximum value of
the energy count register before roll over happens. And for the
ADM1293-2 and ADM1294-2, the maximum energy count is
0x7FFF.
The total power accumulated at the time of the first read is
0x1A × 0x7FFF + 0x02FE = 0xD02E4
The total power accumulated at the time of the second read is
0xF8 × 0x7FFF + 0x2FDC = 0x7C2EE4
The power delta between the two reads is
0x7C2EE4 − 0xD02E4 = 0x6F2C00
And the sample count delta is
0x00602C − 0x004000 = 0x202C
The average power per sample between the two reads is
0x6F2C00 ÷ 0x202C = 0x374 = 884d
To convert this to a real-world value, the first step is to
determine the m coefficient, that is, m = 6126 × 0.25 = 1531.5.
Using Equation 2
X = 1/1531.5 × (884 × 102 − 0)
X = 57.72 W
The energy consumed between the two reads is equal to the
average power by time.
Energy = 57.72 W × 1 sec = 57.72 J
Rev. B | Page 26 of 48
Data Sheet ADM1293/ADM1294
ENERGY METER VALUE TO PMBus STANDARD
DATA CONVERSION
Although the energy meter function on the ADM1293-1/
ADM1294-1 devices is implemented differently to the PMBus
standard, some simple data preprocessing steps can be added to
the processor firmware if the user wants to use the same
software code written for the PMBus standard EIN_READ and
EOUT_READ commands with the ADM1293-1/ADM1294-1
devices. The two data preprocessing steps are
1. Treating ENERGY_COUNT as an unsigned integer.
2. Multiply ROLLOVER_COUNT by 2.
VOLTAGE AND CURRENT CONVERSION USING
LSB VALUES
The direct format voltage and current values returned by the
READ_VIN, READ_VAUX, and READ_IOUT commands and
the corresponding peak versions are the data output directly by
the ADM1293/ADM1294 ADCs. Because the voltages and
currents are 12-bit ADC output codes, they can also be converted
to real-world values when there is knowledge of the size of the
LSB on the ADC.
The m, b, and R coefficients defined for the PMBus conversion
are required to be whole integers by the standard and have,
therefore, been rounded slightly. Using this alternative method,
with the exact LSB values, somewhat more accurate numerical
conversions can be provided.
To convert an ADC code to current in amperes, use the
following formulas:
( )
1+×= ADCCURRENTSENSE ILSBV
SENSE
SENSE
OUT
R
V
I=
where:
VSENSE = VSENSEP − VSENSEN.
LSBCURRENT is the size of the current sense voltage LSB for a given
current sense range.
IADC is the 12-bit ADC code.
IOUT is the measured current value in amperes.
RSENSE is the value of the sense resistor in ohms.
To convert an ADC code to a voltage, use the following formula:
( )
5.0+×=
ADCVOLTAGEM
VLSBV
where:
VM is the measured value in volts.
LSBVOLTAGE is the size of the voltage sensing LSB for a given input
voltage range.
VADC is the 12-bit ADC code.
Table 11. LSB Values
LSB Type Voltage Range (V)1 Current Sense Range (mV)1 LSB Value
LSB Voltage (mV) 0 to 1.2 N/A 0.3
0 to 7.4 N/A 1.801
0 to 21 N/A 5.101
LSB Current Sensing (µV) N/A ±25 12.5
N/A ±50 25
N/A ±100 50
N/A ±200 100
1 N/A means not applicable.
Rev. B | Page 27 of 48
ADM1293/ADM1294 Data Sheet
ALERTx PIN BEHAVIOR
WARNINGS
The sources of a warning are defined as follows:
• CML, a communications error occurred on the I2C bus
• IOUT OC warning from the ADC
• VIN UV warning from the ADC
• VIN OV warning from the ADC
• VAUX UV warning from the ADC
• VAUX OV warning from the ADC
• PIN overpower (OP) warning from the VIN × IOUT
calculation
• Hysteretic output warning from the ADC
A value of 1 in a status register bit field always indicates a
warning condition. Warning bits in the status registers are
latched when set to 1. Use the CLEAR_FAULTS command to
clear a latched bit to 0.
GENERATING AN ALERT
A host device can periodically poll the ADM1293/ADM1294
using the status commands to determine whether a warning is
active. However, this polling is very inefficient in terms of
software and processor resources. The ADM1293/ADM1294
have two output pins (GPO1/ALERT1/CONV and
GPO2/ALERT2) that can be used to generate interrupts to a
host processor.
By default at power-up, the open-drain GPO1/ALERT1/CONV
and GPO2/ALERT2 outputs are high impedance; therefore, the
pins can be pulled high through a resistor. The GPO1/ALERT1/
CONV and GPO2/ALERT2 pins are disabled by default on the
ADM1293/ADM1294.
Any one or more of the warnings listed in the Warnings section
can be enabled and cause an alert, making the corresponding
GPO1/ALERT1/CONV or GPO2/ALERT2 pin active. By
default, the active state of the GPO1/ALERT1/CONV and
GPO2/ALERT2 pins are low.
For example, to use GPO2/ALERT2 to monitor the VAU X UV
warning from the ADC, the followings steps must be performed:
3. Set a threshold level with the VAUX_UV_WARN_LIMIT
command.
4. Set the VAUX_UV_WARN_EN2 bit in the
ALERT2_CONFIG register.
5. Start the power monitor sampling on VAUX. Ensure the
power monitor is configured to sample VAUX in the
PMON_CONFIG register.
If a VAUX sample is taken that is below the configured VAU X
UV value, the GPO2/ALERT2 pin is pulled low, signaling an
interrupt to a processor.
HANDLING/CLEARING AN ALERT
When warnings are configured on the GPO1/ALERT1/CONV
or GPO2/ALERT2 pins, the pin becomes active to signal an
interrupt to the processor. The pin is active low, unless inversion is
enabled. The GPO1/ALERT1/CONV or GPO2/ALERT2 signal
performs the functions of an SMBALERT.
Note that the GPO1/ALERT1/CONV and GPO2/ALERT2 pins
can become active independently but they are always made
inactive together.
A processor can respond to the interrupt in one of two ways.
• If only one device is on the bus, the processor can read the
status bytes and issue a CLEAR_FAULTS command to
clear all the status bits, which causes the deassertion of the
GPO1/ALERT1/CONV or GPO2/ALERT2 line. If the cause
of the SMBALERT is a power monitor generated warning
and that warning persists, providing the power monitor is
running continuously, the next sample generates a new
SMBALERT after the CLEAR_FAULTS command is issued.
• If there are several devices on the bus, the processor can
issue an SMBus alert response address (ARA) command to
find out which device asserted the SMBALERT line. The
processor can read the status bytes from that device and
issue a CLEAR_FAULTS command.
SMBus ALERT RESPONSE ADDRESS (ARA)
The SMBus ARA is a special address that is used by the bus host
to locate any devices that need to communicate with the bus
host. A host typically uses a hardware interrupt pin to monitor
the SMBus alert pins of multiple devices. When the host
interrupt occurs, the host issues a message on the bus using the
SMBus receive byte or receive byte with PEC protocol.
The special address used by the host is 0x0C. Any devices that
have an SMBALERT signal return their own 7-bit address as the
seven MSBs of the data byte. The LSB value is not used and can
be either 1 or 0. The host reads the device address from the
received data byte and proceeds to handle the alert condition.
More than one device may have an active SMBALERT signal
and attempt to communicate with the host. In this case, the
device with the lowest address dominates the bus and succeeds
in transmitting its address to the host. The device that succeeds
disables its SMBus alert signal. If the host sees that the SMBus
alert signal is still low, it continues to read addresses until all
devices that need to communicate have successfully transmitted
their addresses.
Rev. B | Page 28 of 48
Data Sheet ADM1293/ADM1294
EXAMPLE USE OF SMBus ARA
The full sequence of steps that occurs when an SMBALERT is
generated and cleared is as follows:
1. A warning is enabled using the ALERT2_CONFIG command,
and the corresponding status bit for the warning changes from
0 to 1, indicating that the warning has recently become active.
2. The GPO2/ALERT2 pin becomes active (set low) to signal
that an SMBALERT is active.
3. The host processor issues an SMBus ARA command to
determine which device has an active alert.
4. If there are no other active alerts from devices with lower
I2C addresses, this device makes the GPO2/ALERT2 pin
inactive (set high) during the no acknowledge bit period
after it sends its address to the host processor.
5. If the GPO2/ALERT2 pin stays low, the host processor must
continue to issue SMBus ARA commands to devices to
determine the addresses of all devices whose status it must
check.
6. The ADM1293/ADM1294 continue to operate with the
GPO2/ALERT2 pin inactive and the contents of the status
bytes unchanged until the host reads the status bytes and
clears them, or until a new fault occurs. That is, if a status bit
for a fault or warning that is enabled on the GPO2/ALERT2
pin and that was not already active (equal to 1) changes
from 0 to 1, a new alert is generated, causing the
GPO2/ALERT2 pin to become active again.
DIGITAL COMPARATOR MODE
The GPO1/ALERT1/CONV and GPO2/ALERT2 pins can be
configured to indicate if a user defined threshold for voltage,
current, or power is being exceeded. In this mode, the output
pin is live and is not latched when a warning threshold is
exceeded. In effect, the pin acts as a digital comparator, where
the threshold is set using the warning limit threshold commands.
The ALERTx_CONFIG command is used, similar to the
SMBALERT configuration, to select the specific warning
threshold to be monitored. The GPO1/ALERT1/CONV or
GPO2/ALERT2 pin then indicates if the measured value is
above or below the threshold.
Rev. B | Page 29 of 48
ADM1293/ADM1294 Data Sheet
APPLICATION DIAGRAMS
Figure 39 shows an example application circuit of the
ADM1293. With different address pin configurations, up
to 16 ADM1293 devices can share the same I2C bus and are
controlled by the same bus master. Each device can be used to
monitor a supply rail with a voltage ranging from 0 V to 20 V
and report voltage, current, power, and energy consumption.
Each device can also monitor one additional node on the
system using the VAUX input and report the voltage value
present on the node.
The multifunction pins can be configured to indicate status
warnings generated by the ADM1293 either to the microprocessor
or directly to the user by driving a LED. These pins can also be
configured as an ADC conversion signal input to allow
synchronized voltage and current sampling across the system.
Figure 39. ADM1293 Typical Application Diagram
MICRO-
PROCESSOR
SENSEP
VCC
SENSEN
LOAD
1V
3.3V
SDA
SCL
ADR0 GND
ADM1293
12V
I V P E
ADR1
VAUX
VCAP
VIN
SDAO
GPO2/ALERT2
1
GPO1/ALERT1/CONV
2
×16
SENSEP
VCC
SENSEN
LOAD
2.5V
SDA
SCL
ADR0 GND
ADM1293
ADR1
VAUX
VCAP
VIN
SDAO
GPO2/ALERT2
1
GPO1/ALERT1/CONV
2
11891-039
2
CONV IS THE ACTIVE PIN FUNCTION IN THIS SETUP.
1
ALERT2 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.
Rev. B | Page 30 of 48
Data Sheet ADM1293/ADM1294
Rev. B | Page 31 of 48
Figure 40 shows an example application circuit of the
ADM1294. Two of the devices shown are used to monitor a
300 V supply rail and a −48 V supply rail. Both of the devices
communicate with the master device across an isolation barrier.
Separated SDA lines make it easy to set up the bidirectional
communication across the isolation barrier with optocouplers.
The internal shunt regulator allows the ADM1294 to be
powered directly from a wide range of supply voltages. The
ADM3260 I2C and power isolator are used with another
ADM1294. The I2C and power isolator not only greatly
simplifies the cross isolation communication design, but also
can be used to provide power to the ADM1294 and other
circuits on the primary side.
Figure 40. ADM1294 Typical Application Diagram
SENSEP
VSHUNT
RTD
VIN
SENSEN
300V
ADM1294
SDAI
SDAO
SCL
SDAI
SCL
ADR0 ADR1
VEE
VCAP
ISOLATED
DC-TO-DC
VAUX
ADM3260
OPTOCOUPLERS
BIDIRECTONAL
BUS BUFFERS
ISOLATED
DC-TO-DC
EN
3.3V I SO
3.3V ISO
3.3V ISO
3.3V ISO 3.3V
GPO2
1
/ALERT2
GPO1/ALERT1
2
/CONV
GPO2/ALERT2
3
GPO1/ALERT1/CONV
4
SENSEP
VIN
SENSEN
–48V RTN
–48V
–48V
–48V
ADM1294
SDAI
SDAO
SCL
VEE
VCAP
VAUX
VSHUNT ADR0 ADR1
5V
2
ALERT1 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.
3
ALERT2 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.
1
GPO2 IS THEACTIVE PIN FUNCTION IN THIS SETUP.
4
CONV IS THE ACT IVE PI N FUNCTION I N THI S SE TUP.
×16
11891-040
ADM1293/ADM1294 Data Sheet
PMBus COMMAND REFERENCE
Register addresses are in hexadecimal format.
Table 12. PMBus Commands Summary
Address Name Description Reset RW
0x03 CLEAR_FAULTS Clear faults Not applicable W
0x19 CAPABILITY PMBus capability 0xB0 R
0x4A IOUT_OC_WARN_LIMIT IOUT OC warning limit 0x07FF RW
0x57 VIN_OV_WARN_LIMIT VIN OV warning limit 0x0FFF RW
0x58 VIN_UV_WARN_LIMIT VIN UV warning limit 0x0000 RW
0x6B PIN_OP_WARN_LIMIT PIN OP warning limit 0x7FFF RW
0x78
STATUS_BYTE
Status byte
0x00
R
0x79 STATUS_WORD Status word 0x0000 R
0x7B STATUS_IOUT IOUT status 0x00 R
0x7C STATUS_INPUT Input status 0x00 R
0x80 STATUS_MFR_SPECIFIC Manufacturer specific status 0x00 R
0x86 READ_EIN Read EIN 0x000000000000 R
0x87 READ_EOUT Read EOUT 0x000000000000 R
0x88 READ_VIN Read VIN 0x0000 R
0x8C READ_IOUT Read IOUT 0x0000 R
0x97 READ_PIN Read PIN 0x0000 R
0x98 PMBUS_REVISION PMBus revision 0x22 R
0x99 MFR_ID Manufacturer ID 0x494441 R
0x9A MFR_MODEL Manufacturer model R
0x9B MFR_REVISION Manufacturer revision 0x32 R
0xD0 MAX_IOUT Maximum IOUT 0xF800 R
0xD1 PEAK_VIN Peak VIN 0x0000 R
0xD2 PEAK_VAUX Peak VAUX 0x0000 R
0xD3
PMON_CONTROL
Power monitor control
0x01
RW
0xD4 PMON_CONFIG Power monitor configuration 0x0714 RW
0xD5 ALERT1_CONFIG Alert 1 configuration 0x0000 RW
0xD6 ALERT2_CONFIG Alert 2 configuration 0x0000 RW
0xD8 DEVICE_CONFIG Device configuration 0x0000 RW
0xDA MAX_PIN Maximum PIN 0x8000 R
0xDB READ_PIN_EXT Read PIN (extended) 0x000000 R
0xDC READ_EIN_EXT Read EIN (extended) 0x0000000000000000 R
0xDD READ_VAUX Read VAUX 0x0000 R
0xDE VAUX_OV_WARN_LIMIT VAUX OV warning limit 0x0FFF RW
0xDF VAUX_UV_WARN_LIMIT VAUX UV warning limit 0x0000 RW
0xE3
MIN_IOUT
Minimum IOUT
0x7FF
R
0xE4 MIN_PIN Minimum PIN 0x7FFF R
0xE5 READ_EOUT_EXT Read EOUT (extended) 0x0000000000000000 R
0xF2 HYSTERESIS_LOW Hysteresis low threshold level 0x8000 RW
0xF3 HYSTERESIS_HIGH Hysteresis high threshold level 0x7FFF RW
0xF4 STATUS_HYSTERESIS Hysteresis status 0x00 R
Rev. B | Page 32 of 48
Data Sheet ADM1293/ADM1294
PMBus COMMAND DESCRIPTIONS
CLEAR FAULTS REGISTER
Address: 0x03, Reset: 0x, Name: CLEAR_FAULTS
The CLEAR_FAULTS command clears fault and warning bits in all the status registers. All faults and warnings are cleared, but may be
asserted again if it remains active following the next power monitor conversion cycle or bus communication.
This command does not require any data.
PMBus CAPABILITY REGISTER
Address: 0x19, Reset: 0xB0, Name: CAPABILITY
The CAPABILITY command allows the host system to determine the SMBus interface capabilities of the device.
Table 13. Bit Descriptions for CAPABILITY
Bits
Bit Name
Settings
Description
Reset
Access
7
PEC_SUPPORT
Packet error correction (PEC) support.
0x1
R
1
Always reads as 1. PEC is supported.
[6:5] MAX_BUS_SPEED Maximum bus interface speed. 0x1 R
01 Always reads as 01. Maximum supported bus speed is 400 kHz.
4 SMBALERT_SUPPORT SMBALERT support. 0x1 R
1 Always reads as 1. Device supports SMBALERT and the alert response
address (ARA).
[3:0] RESERVED Always reads as 0000b. 0x0 Reserved
IOUT OC WARNING LIMIT REGISTER
Address: 0x4A, Reset: 0x07FF, Name: IOUT_OC_WARN_LIMIT
The IOUT_OC_WARN_LIMIT command sets the overcurrent warning limit for the current measured between the SENSEP and the
SENSEN pins. If the warning limit is a positive number, an overcurrent condition is triggered by a more positive current readback. If the
warning limit is a negative number, an overcurrent condition is triggered by a more negative current readback.
Table 14. Bit Descriptions for IOUT_OC_WARN_LIMIT
Bits
Bit Name
Settings
Description
Reset
Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] IOUT_OC_WARN_LIMIT Overcurrent warning threshold for the IOUT measurement,
expressed in direct format. Set to default value to disable.
0x7FF RW
VIN OV WARNING LIMIT REGISTER
Address: 0x57, Reset: 0x0FFF, Name: VIN_OV_WARN_LIMIT
The VIN_OV_WARN_LIMIT command sets the overvoltage warning limit for the voltage measured on the VIN pin.
Table 15. Bit Descriptions for VIN_OV_WARN_LIMIT
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] VIN_OV_WARN_LIMIT Overvoltage warning threshold for the VIN pin measurement,
expressed in direct format. Set these bits to the default value to
disable.
0xFFF RW
Rev. B | Page 33 of 48
ADM1293/ADM1294 Data Sheet
VIN UV WARNING LIMIT REGISTER
Address: 0x58, Reset: 0x0000, Name: VIN_UV_WARN_LIMIT
The VIN_UV_WARN_LIMIT command sets the undervoltage warning limit for the voltage measured on the VIN pin.
Table 16. Bit Descriptions for VIN_UV_WARN_LIMIT
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] VIN_UV_WARN_LIMIT Undervoltage warning threshold for the VIN pin measurement,
expressed in direct format. Set these bits to the default value to
disable.
0x000 RW
PIN OP WARNING LIMIT REGISTER
Address: 0x6B, Reset: 0x7FFF, Name: PIN_OP_WARN_LIMIT
The PIN_OP_WARN_LIMIT command sets the overpower warning limit for the calculated power value.
If the warning limit is a positive number, an overpower condition is triggered by a more positive power readback. If the warning limit is a
negative number, an overpower condition is triggered by a more negative power readback.
Table 17. Bit Descriptions for PIN_OP_WARN_LIMIT
Bits Bit Name Settings Description Reset Access
[15:0] PIN_OP_WARN_LIMIT Overpower warning threshold for the calculated power, expressed in
direct format. Set these bits to the default value to disable.
0x7FFF RW
STATUS BYTE REGISTER
Address: 0x78, Reset: 0x00, Name: STATUS_BYTE
The STATUS_BYTE command provides status information for communication fault and certain top level status commands in the device.
This is also the lower byte returned by STATUS_WORD. A bit set to 1 indicates a fault or warning has occurred.
Table 18. Bit Descriptions for STATUS_BYTE
Bits Bit Name Settings Description Reset Access
[7:2] RESERVED Always reads as 000000b. 0x00 Reserved
1 CML_FAULT Communication fault. This bit is latched. 0x0 R
0 No communications error detected on the I2C/PMBus interface.
1 An error was detected on the I2C/PMBus interface. Errors detected
are unsupported command, invalid PEC byte, and incorrectly
structured message.
0
NONEABOVE_STATUS
None of the above. This bit is live.
0x0
R
0 No other active status bit reported by any other status command.
1 Active status bits are waiting to be read by one or more status
commands.
STATUS WORD REGISTER
Address: 0x79, Reset: 0x0000, Name: STATUS_WORD
The STATUS_WORD command provides status information for communication faults and all top level status commands in the device.
The lower byte is also returned by STATUS_BYTE.
Table 19. Bit Descriptions for STATUS_WORD
Bits Bit Name Settings Description Reset Access
15 RESERVED Always reads as 0. 0x0 Reserved
14 IOUT_STATUS IOUT warning. This bit is live. 0x0 R
0
There are no active status bits to be read by STATUS_IOUT.
1
There are one or more active status bits to be read by STATUS_IOUT.
Rev. B | Page 34 of 48
Data Sheet ADM1293/ADM1294
Bits Bit Name Settings Description Reset Access
13 INPUT_STATUS Input warning. This bit is live. 0x0 R
0 There are no active status bits to be read by STATUS_INPUT.
1 There are one or more active status bits to be read by
STATUS_INPUT.
12 MFR_STATUS Manufacturer specific warnings. This bit is live. 0x0 R
0 There are no active status bits to be read by STATUS_MFR_SPECIFIC.
1 There are one or more active status bits to be read by
STATUS_MFR_SPECIFIC.
[11:8] RESERVED Always reads as 0000b. 0x0 Reserved
[7:2] RESERVED Duplicate of corresponding bit in STATUS_BYTE. 0x00 Reserved
1
CML_FAULT
Duplicate of corresponding bit in STATUS_BYTE.
0x0
R
0 NONEABOVE_STATUS Duplicate of corresponding bit in STATUS_BYTE. 0x0 R
IOUT STATUS REGISTER
Address: 0x7B, Reset: 0x00, Name: STATUS_IOUT
The STATUS_IOUT command provides status information for warnings related to the IOUT current being monitored.
Table 20. Bit Descriptions for STATUS_IOUT
Bits Bit Name Settings Description Reset Access
[7:6] RESERVED Always reads as 00b. 0x0 Reserved
5 IOUT_OC_WARN IOUT overcurrent warning. 0x0 R
0 No overcurrent condition on the output supply was detected by the
power monitor using the IOUT_OC_WARN_LIMIT command.
1 An overcurrent condition was detected by the power monitor using
the IOUT_OC_WARN_LIMIT command. This bit is latched.
[4:0] RESERVED Always reads as 00000b. 0x00 Reserved
INPUT STATUS REGISTER
Address: 0x7C, Reset: 0x00, Name: STATUS_INPUT
The STATUS_INPUT command provides status information for warnings related to VIN and PIN.
Table 21. Bit Descriptions for STATUS_INPUT
Bits Bit Name Settings Description Reset Access
7 RESERVED Always reads as 0. 0x0 Reserved
6 VIN_OV_WARN VIN overvoltage warning. 0x0 R
0 No overvoltage condition on the VIN pin was detected by the power
monitor using the VIN_OV_WARN_LIMIT command.
1 An overvoltage condition on the VIN pin was detected by the power
monitor using the VIN_OV_WARN_LIMIT command. This bit is latched.
5 VIN_UV_WARN VIN undervoltage warning. 0x0 R
0
No undervoltage condition on the VIN pin was detected by the power
monitor using the VIN_UV_WARN_LIMIT command.
1 An undervoltage condition on the VIN pin was detected by the power
monitor using the VIN_UV_WARN_LIMIT command. This bit is latched.
[4:1] RESERVED Always reads as 0000b. 0x0 Reserved
0 PIN_OP_WARN PIN overpower warning. 0x0 R
0 No overpower condition on the input supply detected by the power
monitor using the PIN_OP_WARN_LIMIT command.
1 An overpower condition on the input supply was detected by the
power monitor using the PIN_OP_WARN_LIMIT command. This bit is
latched.
Rev. B | Page 35 of 48
ADM1293/ADM1294 Data Sheet
MANUFACTURER SPECIFIC STATUS REGISTER
Address: 0x80, Reset: 0x00, Name: STATUS_MFR_SPECIFIC
The STATUS_MFR_SPECIFIC command provides status information for manufacturer specific faults and warnings.
Table 22. Bit Descriptions for STATUS_MFR_SPECIFIC
Bits Bit Name Settings Description Reset Access
7 RESERVED Always reads as 0. 0x0 Reserved
6 VAUX_OV_WARN VAUX overvoltage warning. 0x0 R
0 No overvoltage condition was detected on the VAUX pin by the power
monitor using the VAUX_OV_WARN_LIMIT command.
1 An overvoltage condition was detected on the VAUX pin by the power
monitor using the VAUX_OV_WARN_LIMIT command. This bit is latched.
5 VAUX_UV_WARN VAUX undervoltage warning. 0x0 R
0 No undervoltage condition was detected on the VAUX pin by the
power monitor using the VAUX_UV_WARN_LIMIT command.
1 An undervoltage condition was detected on the VAUX pin by the power
monitor using the VAUX_UV_WARN_LIMIT command. This bit is latched.
[4:0] RESERVED Always reads as 00000b. 0x00 Reserved
READ EIN REGISTER
Address: 0x86, Reset: 0x000000000000, Name: READ_EIN
The READ_EIN command reads the forward flow energy meter registers in a single operation to ensure time consistent data. READ_EIN
accumulates power data when IOUT is positive.
Table 23. Bit Descriptions for READ_EIN
Bits Bit Name Settings Description Reset Access
[47:24] SAMPLE_COUNT This is the total number of PIN samples acquired and accumulated
in both the forward flow and reverse flow energy count
accumulator. Byte 5 is the high byte, Byte 4 is the middle byte, and
Byte 3 is the low byte.
0x000000 R
[23:16] EIN_ROLLOVER_COUNT Number of times that the forward flow energy count has rolled
over. On the ADM1293-1 and ADM1294-1, the rollover counter
increases by 1 each time the energy count rolls over from 0xFFFF
to 0x0000. On the ADM1293-2 and ADM1294-2, the rollover
counter increases by 1 each time the energy count rolls over from
0x7FFF to 0x0000. This is an unsigned 8-bit binary value.
0x00 R
[15:0] EIN_ENERGY_COUNT Forward flow energy accumulator value in direct format. Byte 1 is
the high byte, and Byte 0 is the low byte. On the ADM1293-1 and
ADM1294-1 devices, the data is presented as unsigned integer. On
the ADM1293-2 and ADM1294-2 devices, the data is presented in
twos complement format. Internally, the energy accumulator is a
24-bit value, but only the most significant 16 bits are returned
with this command. Use the READ_EIN_EXT to access the
nontruncated version.
0x0000 R
Rev. B | Page 36 of 48
Data Sheet ADM1293/ADM1294
READ EOUT REGISTER
Address: 0x87, Reset: 0x000000000000, Name: READ_EOUT
The READ_EOUT command reads the reverse flow energy meter registers in a single operation to ensure time consistent data.
READ_EOUT accumulates power data when IOUT is negative.
Table 24. Bit Descriptions for READ_EOUT
Bits Bit Name Settings Description Reset Access
[47:24] SAMPLE_COUNT Duplicate of corresponding bit in READ_EIN. 0x000000 R
[23:16]
EOUT_ROLLOVER_COUNT
Number of times that the reverse flow energy count has rolled
over. On the ADM1293-1 and the ADM1294-1, the rollover
counter increases by 1 each time the energy count rolls over
from 0xFFFF to 0x0000. On the ADM1293-2 and the ADM1294-2,
the rollover counter increases by 1 each time the energy count
rolls over from 0x7FFF to 0x0000. This is an unsigned 8-bit
binary value.
0x00
R
[15:0] EOUT_ENERGY_COUNT Reverse flow energy accumulator value in direct format. Byte 1
is the high byte, and Byte 0 is the low byte. On the ADM1293-1
and ADM1294-1, the data is presented as unsigned integer. On
the ADM1293-2 and ADM1294-2, the data is presented in twos
complement format. Internally, the energy accumulator is a
24-bit value, but only the most significant 16 bits are returned
with this command. Use the READ_EOUT_EXT to access the
nontruncated version.
0x0000 R
READ VIN REGISTER
Address: 0x88, Reset: 0x0000, Name: READ_VIN
The READ_VIN command reads the input voltage, VIN, from the device.
Table 25. Bit Descriptions for READ_VIN
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] READ_VIN Voltage measurement on the VIN pin after averaging, expressed in
direct format.
0x000 R
READ IOUT REGISTER
Address: 0x8C, Reset: 0x0000, Name: READ_IOUT
The READ_IOUT command reads the output current, IOUT, from the device.
Table 26. Bit Descriptions for READ_IOUT
Bits Bit Name Settings Description Reset Access
[15:0]
READ_IOUT
Current measurement derived from differential voltage between the
SENSEP and SENSEN pins, after averaging, expressed in direct format.
0x0000
R
READ PIN REGISTER
Address: 0x97, Reset: 0x0000, Name: READ_PIN
The READ_PIN command reads the calculated input power, PIN, from the device.
Table 27. Bit Descriptions for READ_PIN
Bits Bit Name Settings Description Reset Access
[15:0] READ_PIN Input power calculation, using VIN × IOUT, after averaging, expressed in
direct format.
0x0000 R
Rev. B | Page 37 of 48
ADM1293/ADM1294 Data Sheet
PMBus REVISION REGISTER
Address: 0x98, Reset: 0x22, Name: PMBUS_REVISION
The PMBUS_REVISION command allows the system to read the PMBus revision that the device supports.
Table 28. Bit Descriptions for PMBUS_REVISION
Bits Bit Name Settings Description Reset Access
[7:4] PMBUS_P1_REVISION PMBus Part I Support. 0x2 R
0010 Revision 1.2.
[3:0] PMBUS_P2_REVISION PMBus Part II Support. 0x2 R
0010 Revision 1.2.
MANUFACTURER ID REGISTER
Address: 0x99, Reset: 0x494441, Name: MFR_ID
The MFR_ID command returns a string identifying the manufacturer of the device.
Table 29. Bit Descriptions for MFR_ID
Bits
Bit Name
Settings
Description
Reset
Access
[23:0] MFR_ID String identifying manufacturer as ADI. 0x494441 R
MANUFACTURER MODEL REGISTER
Address: 0x9A, Name: MFR_MODEL
The MFR_MODEL command returns a string identifying the specific model of the device.
Table 30. Bit Descriptions for MFR_MODEL
Bits Bit Name Settings Description Reset Access
[79:0] MFR_MODEL String identifying model as ADM129x-yz, where x identifies the particular
model, y identifies the particular model type, and z identifies the grade.
R
MANUFACTURER REVISION REGISTER
Address: 0x9B, Reset: 0x32, Name: MFR_REVISION
The MFR_REVISION command returns a string identifying the hardware revision of the device.
Table 31. Bit Descriptions for MFR_REVISION
Bits Bit Name Settings Description Reset Access
[7:0]
MFR_REVISION
String identifying hardware revision in ASCII code, for example 0x32 for 2.
0x32
R
MAXIMUM IOUT REGISTER
Address: 0xD0, Reset: 0xF800, Name: MAX_IOUT
The MAX_IOUT command reports the most positive IOUT value recorded, expressed in direct format. Writing a 0 with this command
resets it to the default value.
Table 32. Bit Descriptions for MAX_IOUT
Bits Bit Name Settings Description Reset Access
[15:0] MAX_IOUT Reports the most positive IOUT value recorded, expressed in direct
format. Writing 0 with this command resets it to the default value.
0xF800 R
Rev. B | Page 38 of 48
Data Sheet ADM1293/ADM1294
PEAK VIN REGISTER
Address: 0xD1, Reset: 0x0000, Name: PEAK_VIN
The PEAK_VIN command reports the most positive VIN value recorded, expressed in direct format. Writing a 0 with this command
resets it to the default value.
Table 33. Bit Descriptions for PEAK_VIN
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0]
PEAK_VIN
Reports the most positive VIN value recorded, expressed in direct
format. Writing 0 with this command resets it to the default value.
0x000
R
PEAK VAUX REGISTER
Address: 0xD2, Reset: 0x0000, Name: PEAK_VAUX
The PEAK_VAUX command reports the most positive VAUX value recorded, expressed in direct format. Writing a 0 with this command
resets it to the default value.
Table 34. Bit Descriptions for PEAK_VAUX
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] PEAK_VAUX Reports the most positive VAUX value recorded, expressed in direct
format. Writing 0 with this command resets it to the default value.
0x000 R
POWER MONITOR CONTROL REGISTER
Address: 0xD3, Reset: 0x01, Name: PMON_CONTROL
The PMON_CONTROL command starts and stops the power monitor.
Table 35. Bit Descriptions for PMON_CONTROL
Bits Bit Name Settings Description Reset Access
[7:1] RESERVED Always reads as 0000000b. 0x00 Reserved
0 CONVERT Convert enable. 0x1 RWAS
0 Power monitor is not running.
1 Power monitor is sampling. In single shot mode, this bit clears itself
after one complete cycle. In continuous mode, this bit must be written
to 0 to stop sampling. A rising edge on a convert (CONV) input pin sets
this bit to 1. During sampling, additional rising edges on CONV are
ignored.
Rev. B | Page 39 of 48
ADM1293/ADM1294 Data Sheet
POWER MONITOR CONFIGURATION REGISTER
Address: 0xD4, Reset: 0x0714, Name: PMON_CONFIG
The PMON_CONFIG command is used to configure the power monitor. Different combinations of channels can be included in the
sampling round robin, and averaging can be set for different measurements.
Table 36. Bit Descriptions for PMON_CONFIG
Bits Bit Name Settings Description Reset Access
15 RESERVED Always reads as 0. 0x0 Reserved
14
SIMULTANEOUS
Simultaneous sampling mode enable.
0x0
RW
0 Simultaneous sampling disabled.
1 Simultaneous sampling enabled.
[13:11] PWR_AVG PIN averaging mode select. 0x0 RW
000 Disables sample averaging for power.
001 Sets sample averaging for power to two samples.
010 Sets sample averaging for power to four samples.
011 Sets sample averaging for power to eight samples.
100 Sets sample averaging for power to 16 samples.
101 Sets sample averaging for power to 32 samples.
110 Sets sample averaging for power to 64 samples.
111 Sets sample averaging for power to 128 samples.
[10:8] VI_AVG VIN/VAUX/IOUT averaging mode select. 0x7 RW
000 Disables sample averaging for current and voltage.
001 Sets sample averaging for current and voltage to two samples.
010 Sets sample averaging for current and voltage to four samples.
011 Sets sample averaging for current and voltage to eight samples.
100 Sets sample averaging for current and voltage to 16 samples.
101 Sets sample averaging for current and voltage to 32 samples.
110 Sets sample averaging for current and voltage to 64 samples.
111 Sets sample averaging for current and voltage to 128 samples.
[7:6] IRANGE Current sense range (CSR) select. 0x0 RW
00 Sets current sense range to ±25 mV.
01 Sets current sense range to ±50 mV.
10 Sets current sense range to ±100 mV.
11
Sets current sense range to ±200 mV.
5 RESERVED Always reads as 0. 0x0 Reserved
4 PMON_MODE Conversion mode select. 0x1 RW
0 Single shot sampling.
1 Continuous sampling.
[3:2] VIN_SEL VIN Sampling mode select. 0x1 RW
00 VIN sampling disabled.
01 VIN sampling as direct ADC input with full scale of 1.2 V.
10 VIN sampling with ADC full scale of 7.4 V.
11 VIN sampling with ADC full scale of 21 V.
1 VAUX_EN VAUX sampling enable. 0x0 RW
0 VAUX sampling disabled.
1 VAUX sampling enabled.
0 RESERVED Always reads as 0. 0x0 Reserved
Rev. B | Page 40 of 48
Data Sheet ADM1293/ADM1294
ALERT 1 CONFIGURATION REGISTER
Address: 0xD5, Reset: 0x0000, Name: ALERT1_CONFIG
The ALERT1_CONFIG command allows different combinations of faults and warnings to be configured on the GPO1/ALERT1/CONV
output pin. The pin can operate in different modes, configured using the DEVICE_CONFIG command.
Table 37. Bit Descriptions for ALERT1_CONFIG
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
11 CML_ERROR_EN1 Communications error enable. 0x0 RW
10 IOUT_OC_WARN_EN1 IOUT overcurrent warning enable. 0x0 RW
9 HYSTERETIC_EN1 Hysteretic output enable. 0x0 RW
8 VIN_OV_WARN_EN1 VIN overvoltage warning enable. 0x0 RW
7 VIN_UV_WARN_EN1 VIN undervoltage warning enable. 0x0 RW
6 VAUX_OV_WARN_EN1 VAUX overvoltage warning enable. 0x0 RW
5 VAUX_UV_WARN_EN1 VAUX undervoltage warning enable. 0x0 RW
4 RESERVED Always reads as 0. 0x0 Reserved
3
PIN_OP_WARN_EN1
PIN overpower warning enable.
0x0
RW
[2:0] RESERVED Always reads as 000b. 0x0 Reserved
ALERT 2 CONFIGURATION REGISTER
Address: 0xD6, Reset: 0x0000, Name: ALERT2_CONFIG
The ALERT2_CONFIG command allows different combinations of faults and warnings to be configured on the GPO2/ALERT2 output
pin. The pin can operate in different modes, configured using the DEVICE_CONFIG command.
Table 38. Bit Descriptions for ALERT2_CONFIG
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
11 CML_ERROR_EN2 Communications error enable. 0x0 RW
10 IOUT_OC_WARN_EN2 IOUT overcurrent warning enable. 0x0 RW
9 HYSTERETIC_EN2 Hysteretic output enable. 0x0 RW
8 VIN_OV_WARN_EN2 VIN overvoltage warning enable. 0x0 RW
7 VIN_UV_WARN_EN2 VIN undervoltage warning enable. 0x0 RW
6 VAUX_OV_WARN_EN2 VAUX overvoltage warning enable. 0x0 RW
5 VAUX_UV_WARN_EN2 VAUX undervoltage warning enable. 0x0 RW
4 RESERVED Always reads as 0. 0x0 Reserved
3 PIN_OP_WARN_EN2 PIN overpower warning enable. 0x0 RW
[2:0]
RESERVED
Always reads as 000b.
0x0
Reserved
Rev. B | Page 41 of 48
ADM1293/ADM1294 Data Sheet
DEVICE CONFIGURATION REGISTER
Address: 0xD8, Reset: 0x0000, Name: DEVICE_CONFIG
The DEVICE_CONFIG command configures the GPO1/GPO2 output modes.
Table 39. Bit Descriptions for DEVICE_CONFIG
Bits Bit Name Settings Description Reset Access
[15:11] RESERVED Always reads as 0000b. 0x0 Reserved
10 PWR_HYST_EN Power hysteretic comparison enable. When enabled the hysteresis
functions refer to power rather than current. The HYSTERETIC_EN bit
also needs to be set in ALERT_CONFIG.
0x0 RW
0 Current hysteresis mode.
1 Power hysteresis mode.
[9:8] GPO2_MODE GPO2 configuration mode. 0x0 RW
00 Default. GPO2 is configured to generate SMBALERTs.
01 GPO2 can be used a general-purpose digital output pin. The
GPO2_INVERT bit is used to change the output state.
10 Reserved.
11 Digital comparator mode. The output pin now reflects the live status of
the warning or fault bit selected for the output. In effect, this is a
nonlatched SMBALERT.
7 GPO2_INVERT GPO invert mode. 0x0 RW
0 In SMBALERT mode the output is not inverted, and active low. In GPO
mode, the output is set low.
1 In SMBALERT mode the output is inverted, and active high. In GPO
mode, the output is set high.
[6:5] GPO1_MODE GPO1 configuration mode. 0x0 RW
00 Default. GPO1 is configured to generate SMBALERTs.
01
GPO1 can be used a general-purpose digital output pin. The
GPO1_INVERT bit is used to change the output state.
10 GPO1 is configured as a convert (CONV) input pin.
11 Digital comparator mode. The output pin reflects the live status of the
warning or fault bit selected for the output. In effect, this is a
nonlatched SMBALERT.
4 GPO1_INVERT GPO1 invert mode. 0x0 RW
0 In SMBALERT mode, the output is not inverted, and active low. In GPO
mode, the output is set low.
1 In SMBALERT mode the output is inverted, and active high. In GPO
mode, the output is set high.
[3:0] RESERVED Always reads as 0000b. 0x0 Reserved
MAXIMUM PIN REGISTER
Address: 0xDA, Reset: 0x8000, Name: MAX_PIN
The MAX_PIN command reports the most positive PIN value recorded, expressed in direct format. Writing 0 with this command resets
it to the default value.
Table 40. Bit Descriptions for MAX_PIN
Bits Bit Name Settings Description Reset Access
[15:0] MAX_PIN Reports the most positive PIN value recorded, expressed in direct format.
Writing 0 with this command resets it to the default value.
0x8000 R
Rev. B | Page 42 of 48
Data Sheet ADM1293/ADM1294
READ PIN (EXTENDED) REGISTER
Address: 0xDB, Reset: 0x000000, Name: READ_PIN_EXT
The READ_PIN_EXT command reads the extended precision version of the calculated input power, PIN, from the device.
Table 41. Bit Descriptions for READ_PIN_EXT
Bits Bit Name Settings Description Reset Access
[23:0] READ_PIN_EXT Extended precision version of input power calculation, PIN, expressed in
direct format.
0x000000 R
READ EIN (EXTENDED) REGISTER
Address: 0xDC, Reset: 0x0000000000000000, Name: READ_EIN_EXT
The READ_EIN_EXT command reads the extended precision version of the forward flow energy meter register, EIN, from the device.
Table 42. Bit Descriptions for READ_EIN_EXT
Bits Bit Name Settings Description Reset Access
[63:40]
SAMPLE_COUNT
These bits report the total number of PIN samples acquired and
accumulated in both the forward and reverse flow energy count
accumulator. Byte 7 is the high byte, Byte 6 is the middle byte, and
Byte 5 is the low byte.
0x000000
R
[39:24] EIN_ROLLOVER_EXT These bits report the number of times that the forward flow energy
count has rolled over. On the ADM1293-1 and ADM1294-1, the
rollover counter increases by 1 each time the energy count rolls over
from 0xFFFFFF to 0x000000. On the ADM1293-2 and ADM1294-2, the
rollover counter increases by 1 each time the energy count rolls over
from 0x7FFFFF to 0x000000. This is an unsigned 16-bit binary value.
Byte 4 is the high byte, and Byte 3 is the low byte.
0x0000 R
[23:0] EIN_ENERGY_EXT Extended precision forward flow energy accumulator value in direct
format. Byte 2 is the high byte, and Byte 0 is the low byte. On the
ADM1293-1 and ADM1294-1, the data is presented as unsigned
integer. On the ADM1293-2 and ADM1294-2, the data is presented in
twos complement format.
0x000000 R
READ VAUX REGISTER
Address: 0xDD, Reset: 0x0000, Name: READ_VAUX
The READ_VAUX command reads the auxiliary input voltage, VVAU X , from the device.
Table 43. Bit Descriptions for READ_VAUX
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] READ_VAUX Voltage measurement on VAUX pin after averaging, expressed in direct
format.
0x000 R
VAUX OV WARNING LIMIT REGISTER
Address: 0xDE, Reset: 0x0FFF, Name: VAUX_OV_WARN_LIMIT
The VAUX_OV_WARN_LIMIT command sets the overvoltage warning limit for the voltage measured on the VAUX pin.
Table 44. Bit Descriptions for VAUX_OV_WARN_LIMIT
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] VAUX_OV_WARN_LIMIT Overvoltage warning threshold for the VAUX pin measurement,
expressed in direct format. Set these bits to the default value to
disable.
0xFFF RW
Rev. B | Page 43 of 48
ADM1293/ADM1294 Data Sheet
VAUX UV WARNING LIMIT REGISTER
Address: 0xDF, Reset: 0x0000, Name: VAUX_UV_WARN_LIMIT
The VAUX_UV_WARN_LIMIT command sets the undervoltage warning limit for the voltage measured on the VAUX pin.
Table 45. Bit Descriptions for VAUX_UV_WARN_LIMIT
Bits Bit Name Settings Description Reset Access
[15:12] RESERVED Always reads as 0000b. 0x0 Reserved
[11:0] VAUX_UV_WARN_LIMIT Undervoltage warning threshold for the VAUX pin measurement,
expressed in direct format. Set these bits to the default value to
disable.
0x000 RW
MINIMUM IOUT REGISTER
Address: 0xE3, Reset: 0x7FF, Name: MIN_IOUT
The MIN_IOUT command reports the most negative IOUT value recorded, expressed in direct format. Writing 0 with this command
resets it to the default value.
Table 46. Bit Descriptions for MIN_IOUT
Bits Bit Name Settings Description Reset Access
[15:0] MIN_IOUT Reports the most negative IOUT value recorded, expressed in direct
format. Writing 0 with this command resets it to the default value.
0x7FF R
MINIMUM PIN REGISTER
Address: 0xE4, Reset: 0x7FFF, Name: MIN_PIN
The MIN_PIN command reports the most negative PIN value recorded, expressed in direct format. Writing 0 with this command resets it
to the default value.
Table 47. Bit Descriptions for MIN_PIN
Bits Bit Name Settings Description Reset Access
[15:0] MIN_PIN Reports the most negative PIN value recorded, expressed in direct format.
Writing 0 with this command resets it to the default value.
0x7FFF R
READ EOUT (EXTENDED) REGISTER
Address: 0xE5, Reset: 0x0000000000000000, Name: READ_EOUT_EXT
The READ_EOUT_EXT command reads the extended precision version of the reverse flow energy meter register, EOUT, from the
device.
Table 48. Bit Descriptions for READ_EOUT_EXT
Bits Bit Name Settings Description Reset Access
[63:40] SAMPLE_COUNT Duplicate of corresponding bit in READ_EIN_EXT. 0x000000 R
[39:24] EOUT_ROLLOVER_EXT Reports the number of times that the reverse flow energy count has
rolled over. On the ADM1293-1 and ADM1294-1, the rollover
counter increases by 1 each time the energy count rolls over from
0xFFFFFF to 0x000000. On the ADM1293-2 and ADM1294-2, the
rollover counter increases by 1 each time the energy count rolls
over from 0x7FFFFF to 0x000000. This is an unsigned 16-bit binary
value. Byte 4 is the high byte, and Byte 3 is the low byte.
0x0000 R
[23:0]
EOUT_ENERGY_EXT
Extended precision reverse flow energy accumulator value in direct
format. Byte 2 is the high byte, and Byte 0 is the low byte. On the
ADM1293-1 and ADM1294-1, the data is presented as unsigned
integer. On the ADM1293-2 and ADM1294-2, the data is presented
in twos complement format.
0x000000
R
Rev. B | Page 44 of 48
Data Sheet ADM1293/ADM1294
HYSTERESIS LOW THRESHOLD LEVEL REGISTER
Address: 0xF2, Reset: 0x8000, Name: HYSTERESIS_LOW
The HYSTERESIS_LOW command sets the lower threshold used to generate the hysteretic output signal that is available on a GPOx pin.
Table 49. Bit Descriptions for HYSTERESIS_LOW
Bits Bit Name Settings Description Reset Access
[15:0] HYSTERESIS_LOW Value setting the lower hysteresis threshold, expressed in direct format. 0x8000 RW
HYSTERESIS HIGH THREHSOLD LEVEL REGISTER
Address: 0xF3, Reset: 0x7FFF, Name: HYSTERESIS_HIGH
The HYSTERESIS_HIGH command sets the higher threshold that generates the hysteretic output signal that is available on a GPOx pin.
Table 50. Bit Descriptions for HYSTERESIS_HIGH
Bits Bit Name Settings Description Reset Access
[15:0] HYSTERESIS_HIGH Value setting the higher hysteresis threshold, expressed in direct format. 0x7FFF RW
HYSTERESIS STATUS REGISTER
Address: 0xF4, Reset: 0x00, Name: STATUS_HYSTERESIS
The STATUS_HYSTERESIS status register reports if the hysteretic comparison is above or below the user defined HYSTERESIS_HIGH
and HYSTERESIS_LOW thresholds, the resulting hysteretic output and the IOUT_OC_WARNING status bit.
Table 51. Bit Descriptions for STATUS_HYSTERESIS
Bits Bit Name Settings Description Reset Access
[7:4] RESERVED Always reads as 0000b. 0x0 Reserved
3 IOUT_OC_WARN IOUT overcurrent warning. 0x0 R
0 No overcurrent condition on the output supply detected by the power
monitor using the IOUT_OC_WARN_LIMIT command.
1 An overcurrent condition was detected by the power monitor using the
IOUT_OC_WARN_LIMIT command.
2 HYST_STATE Hysteretic comparison output. 0x0 R
0 Comparison output low.
1 Comparison output high.
1 HYST_GT_HIGH Hysteretic upper threshold comparison. 0x0 R
0 Compared value is equal or below upper threshold.
1 Compared value is above upper threshold.
0 HYST_LT_LOW Hysteretic lower threshold comparison. 0x0 R
0 Compared value is equal or above the lower threshold.
1 Compared value is below the lower threshold.
Rev. B | Page 45 of 48
ADM1293/ADM1294 Data Sheet
Rev. B | Page 46 of 48
OUTLINE DIMENSIONS
Figure 41. 16-Lead Lead Frame Chip Scale Package [LFCSP_WQ]
4 mm × 4 mm Body, Very Very Thin Quad
(CP-16-17)
Dimensions shown in millimeters
Figure 42. 14-Lead Thin Shrink Small Outline Package [TSSOP]
RU-14
Dimensions shown in millimeters
2.70
2.60 SQ
2.50
COMPLIANT
TO
JEDEC STANDARDS MO-220-WGGC.
1
0.65
BSC
BOTTOM VIEWTOP VIEW
16
5
8
9
12 13
4
EXPOSED
PAD
PIN1
INDICATOR
4.10
4.00 SQ
3.90
0.45
0.40
0.35
S
EATING
PLANE
0.80
0.75
0.70 0.05 MAX
0.02 NOM
0.20 REF
0.20 MIN
COPLANARITY
0.08
PIN 1
INDICATOR
0.35
0.30
0.25
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CONFIGURATION AND
FUNCTION DESCRIPTIONS
SECTION OF THIS DATA SHEET.
08-16-2010-C
COMPL IANT T O JE DE C STANDA RDS M O- 153-AB-1
061908-A
8°
0°
4.50
4.40
4.30
14 8
7
1
6.40
BSC
PIN 1
5.10
5.00
4.90
0.65 BSC
0.15
0.05 0.30
0.19
1.20
MAX
1.05
1.00
0.80 0.20
0.09 0.75
0.60
0.45
COPLANARITY
0.10
SEATING
PLANE
Data Sheet ADM1293/ADM1294
ORDERING GUIDE
Model
1
Temperature Range
2
Grade
Package Description
Package Option
ADM1293-1AACPZ
−40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1293-1AACPZ-RL7 −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1293-1BACPZ −40°C to +105°C B 16-Lead LFCSP_WQ CP-16-17
ADM1293-1BACPZ-RL7 −40°C to +105°C B 16-Lead LFCSP_WQ CP-16-17
ADM1293-1AARUZ −40°C to +105°C A 14-Lead TSSOP RU-14
ADM1293-1AARUZ-RL7 −40°C to +105°C A 14-Lead TSSOP RU-14
ADM1293-1BARUZ −40°C to +105°C B 14-Lead TSSOP RU-14
ADM1293-1BARUZ-RL7 −40°C to +105°C B 14-Lead TSSOP RU-14
ADM1293-2AACPZ −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1293-2AACPZ-RL −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1294-1AACPZ −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1294-1AACPZ-RL7 −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1294-1BACPZ −40°C to +105°C B 16-Lead LFCSP_WQ CP-16-17
ADM1294-1BACPZ-RL7 −40°C to +105°C B 16-Lead LFCSP_WQ CP-16-17
ADM1294-1AARUZ −40°C to +105°C A 14-Lead TSSOP RU-14
ADM1294-1AARUZ-RL7 −40°C to +105°C A 14-Lead TSSOP RU-14
ADM1294-1BARUZ −40°C to +105°C B 14-Lead TSSOP RU-14
ADM1294-1BARUZ-RL7 −40°C to +105°C B 14-Lead TSSOP RU-14
ADM1294-2AACPZ −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
ADM1294-2AACPZ-RL −40°C to +105°C A 16-Lead LFCSP_WQ CP-16-17
EVAL-ADM1293EBZ Evaluation Kit
EVAL-ADM1294EBZ Evaluation Kit
1 Z = RoHS Compliant Part.
2 The operation temperature is specified as ambient for ADM1293 and junction for ADM1294.
Rev. B | Page 47 of 48
ADM1293/ADM1294 Data Sheet
Rev. B | Page 48 of 48
NOTES
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
©2014–2015 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D11891-0-3/15(B)
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ADM1294-1AARUZ ADM1293-1AARUZ EVAL-ADM1294EBZ EVAL-ADM1293EBZ ADM1294-1AACPZ ADM1293-
1AACPZ-RL7 ADM1293-1BACPZ-RL7 ADM1293-1BARUZ ADM1293-1BARUZ-RL7 ADM1294-1AARUZ-RL7
ADM1293-1BACPZ ADM1294-1BACPZ-RL7 ADM1294-1AACPZ-RL7 ADM1293-1AACPZ ADM1293-1AARUZ-RL7
ADM1294-1BACPZ
