ADM1294-1BARUZ-RL7_技术文档

Digital Power Monitor with

PMBus Interface

Data Sheet

ADM1293/ADM1294

FEATURES

FUNCTIONAL BLOCK DIAGRAMS

SENSEP

SENSEN

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

ADM1293

VCC

INTERNAL

SUPPLY

LDO

VCAP

RANGE

SELECT

MUX

ADC

EN

VIN

VAUX

Power accumulation for energy metering

Bidirectional current sensing

GPO1/ALERT1/CONV

GPO2/ALERT2

ADDRESS

DECODER

PMBUS AND LOGIC

Digitally programmable overcurrent alert

Multifunctional pins with user configurable functions

ADC conversion enable input

ADR1 ADR2

GND SCL SDAI SDAO

Figure 1. ADM1293 Functional Block Diagram

Multisource alert output

User-controllable GPO

Peak detect registers for current, voltage, and power

PMBus fast mode compliant interface

VSHUNT

VCAP

ADM1294

LDO

ADR1

ADDRESS

DECODER

VEE

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 T_A= −40°C to +105°C

ADM1294 T_J= −40°C to +105°C

ADR2

IC POWER SUPPLY

GPO1/ALERT1/CONV

GPO2/ALERT2

RANGE

SELECT

MUX

VIN

PMBUS

AND

LOGIC

ADC

EN

SDAI

SDAO

SCL

VAUX

VEE

APPLICATIONS

SENSEN

SENSEP

Power monitoring/power budgeting

Central office equipment

Figure 2. ADM1294 Functional Block Diagram

Telecommunications and data communications equipment

PCs/servers

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.

In conditions such as overcurrent, overvoltage, undervoltage,

and overpower, the ADM1293/ADM1294 devices can generate

an interrupt signal to the microprocessor through the

GPOx/

outputs. The threshold for these conditions is

ALERTx

digitally programmed via PMBus.

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.

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.

Rev. B

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ADM1293/ADM1294

Data Sheet

TABLE OF CONTENTS

Features .............................................................................................. 1

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

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

ALERTx

GPOx and

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

Rev. B | Page 2 of 48

Data Sheet

ADM1293/ADM1294

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

Rev. B | Page 3 of 48

ADM1293/ADM1294

Data Sheet

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

For the ADM1293: VCC = 2.95 V to 20 V, V_SENSEP= 0 V to 20 V, VCC ≥ V_SENSEP, VCC ≥ V_SENSEN, T_A= −40°C to +105°C, unless otherwise noted.

For the ADM1294: VEE = −48 V, shunt regulation current = 10 mA, V_SENSEP= VEE = 0 V, pin voltages are referenced to the VEE pin, T_J=

−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 T_A= 25°C.

Table 1.

Parameter

POWER SUPPLY

ADM1293

Symbol Min Typ

Max

Unit

Test Conditions/Comments

VCC rising

Operating Voltage Range

Undervoltage Lockout (UVLO)

UVLO Hysteresis

V_OP3

V_{UVLO_3}

2.95

2.4

20

V

mV

mA

2.7

120

3.3

90

Quiescent Current

I_CC3

ADM1294

Typical Operating Voltage

Voltage Transient Immunity

Shunt Regulation Voltage

V_OP4

2.95

V_SHUNT

13

V

Reference to VEE

200

V_SHUNT

V_{UVLO_4}

11.5 12.3

I_IN= 3.3 mA to 30 mA, maximum I_INdependent on T_Aand

θ_JA(see the Powering the ADM1294 section)

V_SHUNTrising

Undervoltage Lockout

UVLO Hysteresis

Quiescent Current

2.4

90

2.7

120

3.6

V

mV

mA

V

I_CC4

V_SHUNT= 13 V

Power Directly Without Shunt V_DIR

SENSEP AND SENSEN PINS

ADM1293

2.95

11.5

Input Current

Input Imbalance

ADM1294

I_{IN_SENSE3}

I_ΔSENSE3

25

nA

Per individual pin, V_SENSEP= V_SENSEN= VCC = 20 V

I_ΔSENSEx= I_SENSEP− I_SENSEN, V_SENSE= 20 mV, V_SENSEP= V_VSHUNT

5

Input Current

Input Imbalance

I_{IN_SENSE4}

I_ΔSENSE4

−1

1

µA

V_SENSEP= V_SENSEN≤ 25 mV, per individual pin, V_VSHUNT= 12 V

0.05

I_ΔSENSEx= I_SENSEP− I_SENSEN, V_SENSE= 20 mV, V_SENSEP= 0 V, V_VSHUNT

12 V

=

VCAP PIN

Internally Regulated Voltage

VIN PIN

Input Current

V_VCAP

I_VIN

2.66 2.7

2.74

20

V

0 µA ≤ I_VCAP≤ 100 µA, C_VCAP= 1 μF

µA

V_VIN= 20 V, V_RANGE= 0 V to 21 V

V_VIN= 1.2 V, V_RANGE= 0 V to 1.2 V

100 nA

VAUX PIN

Input Current

I_VAUX

100 nA

V_VAUX= 1.2 V, VAUX sampling enabled

GPO1/ALERT1/CONV PIN

Output Low Voltage

V_{OL_GPO1}

0.4

1.5

V

I_GPO1= 1 mA

I_GPO1= 5 mA

Leakage Current

100 nA

V_GPO1≤ 2 V, GPO1 output high-Z

V_GPO1= 20 V, GPO1 output high-Z

Configured as CONV pin

1

µA

V

Input High Voltage

Input Low Voltage

Glitch Filter

V_IH

V_IL

1.1

0.8

V

1

µs

GPO2/ALERT2 PIN

Output Low Voltage

V_{OL_GPO2}

0.4

1.5

V

I_GPO2= 1 mA

I_GPO2= 5 mA

Leakage Current

100 nA

µA

V_GPO2≤ 2 V, GPO2 output high-Z

V_GPO2= 20 V, GPO2 output high-Z

1

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, V_SENSEP= 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

0.72

2.65

1

0.35

0.44

0.59

1

2

5

0.26

0.4

0.23

0.3

%

V_SENSE= 20 mV

V_SENSE= 20 mV, 16 sample averaging

V_SENSE= 20 mV, one sample averaging

V_SENSE= 20 mV, V_SENSEP= 18 V to 20 V

V_SENSE= 25 mV

V_SENSE= 15 mV

V_SENSE= 10 mV

V_SENSE= 5 mV

V_SENSE= 2.5 mV

V_SENSE= 1 mV

V_SENSE= 40 mV

CSR = 50 mV

CSR = 100 mV

CSR = 200 mV

V_SENSE= 20 mV

V_SENSE= 80 mV

V_SENSE= 40 mV

V_SENSE= 160 mV

0.21

0.27

V_SENSE= 80 mV

Voltage Sense Absolute Error

VIN

128 sample averaging

V_VIN= 10 V to 20 V, V_RANGE= 21 V

V_VIN= 3.6 V to 7.4 V, V_RANGE= 7.4 V

V_VIN= 0.6 V to 1.2 V, V_RANGE= 1.2 V, T_A= −40°C to +85°C

V_VIN= 0.6 V to 1.2 V, V_RANGE= 1.2 V

V_VAUX= 0.6 V to 1.2 V, T_A= −40°C to +85°C

V_VAUX= 0.6 V to 1.2 V

0.35

0.26

0.2

0.24

0.2

%

VAUX

0.24

0.48

Power Absolute Error

V_SENSE= 20 mV, SENSEP = VIN = 12 V, V_RANGE= 21 V, T_A=

−40°C to +85°C

0.54

0.5

%

V_SENSE= 20 mV, SENSEP = VIN = 12 V, V_RANGE= 21 V

V_SENSE= 20 mV, SENSEP = VIN = 3.3 V, V_RANGE= 7.4 V, T_A=

−40°C to +85°C

0.54

0.48

%

V_SENSE= 20 mV, SENSEP = VIN = 3.3 V, V_RANGE= 7.4 V

V_SENSE= 20 mV, SENSEP = 20 mV, VIN = 0.8 V, V_RANGE

1.2 V, T_A= −40°C to +85°C

=

0.53

%

V_SENSE= 20 mV, SENSEP = 20 mV, VIN = 0.8 V, V_RANGE= 1.2 V

GRADE B DEVICE CURRENT AND

VOLTAGE MONITORING

Current Sense Absolute Error

CSR = 25 mV

128 sample averaging (unless otherwise noted)

V_SENSE= V_SENSEP− V_SENSEN= 20 mV, T_A= −40°C to +85°C

V_SENSE= 20 mV

V_SENSE= 20 mV, 16 sample averaging

V_SENSE= 20 mV, one sample averaging

V_SENSE= 20 mV, V_SENSEP= 18 V to 20 V

V_SENSE= 25 mV

V_SENSE= 15 mV

V_SENSE= 10 mV

V_SENSE= 2.5 mV

V_SENSE= 1 mV

0.1

0.75

0.84

1.6

5.8

2.2

0.8

1

1.3

4.5

11

%

CSR = 50 mV

0.57

0.9

V_SENSE= 40 mV

V_SENSE= 20 mV

Rev. B | Page 5 of 48

ADM1293/ADM1294

Data Sheet

Parameter

Symbol Min Typ

Max

0.55

0.7

Unit

%

Test Conditions/Comments

V_SENSE= 80 mV

V_SENSE= 40 mV

CSR = 100 mV

CSR = 200 mV

0.5

%

V_SENSE= 160 mV

0.6

%

V_SENSE= 80 mV

Voltage Sense Absolute Error

VIN

128 sample averaging

V_VIN= 10 V to 20 V, V_RANGE= 21 V

V_VIN= 3.6 V to 7.4 V, V_RANGE= 7.4 V

V_VIN= 0.6 V to 1.2 V, V_RANGE= 1.2 V, T_A= −40°C to +85°C

V_VIN= 0.6 V to 1.2 V, V_RANGE= 1.2 V

V_VAUX= 0.6 V to 1.2 V, T_A= −40°C to +85°C

V_VAUX= 0.6 V to 1.2 V

V_SENSE= 20 mV, SENSEP = VIN = 12 V, V_RANGE= 21 V

V_SENSE= 20 mV, SENSEP = VIN = 3.3 V, V_RANGE= 7.4 V

V_SENSE= 20 mV, SENSEP = 20 mV, VIN = 0.8 V, V_RANGE= 1.2 V

Includes time for power multiplication

0.8

0.6

0.45

0.6

0.45

0.6

1.2

%

VAUX

Power Absolute Error

ADC CONVERSION TIME

144

64

165

73

µs

One sample of IOUT, from command received to valid

data in register

One sample of VIN, from command received to valid data

in register

One sample of VAUX, from command received to valid

data in register

64

73

ADRx PINS

Address Set to 00

0

0.8

V

Connect to VEE

Input Current for Address 00

Address Set to 01

Address Set to 10

−40 −22

135 150

−1

2

μA

kΩ

μA

V

V_ADRx= 0 V to 0.8 V

Resistor to VEE

No connect state, maximum leakage current allowed

Connect to VCAP

165

+1

Address Set to 11

Input Current for Address 11

3

10

μA

V_ADRx= 2.0 V to VCAP, must not exceed the maximum

allowable current draw from VCAP

SERIAL BUS DIGITAL I/O

Input High Voltage

Input Low Voltage

SDAO Output Low Voltage

Input Leakage

SDAI, SDAO, SCL

I_OL= 4 mA

V_IH

V_IL

V_OL

I_{LEAK_PIN}

1.1

V

μA

V

pF

ns

0.8

0.4

+10

+5

−10

−5

2.7

Device is not powered

3 V to 5 V 10%

Nominal Bus Voltage

Capacitance for I/O Pins

Input Glitch Filter

V_DD

C_PIN

t_SP

5.5

5

0

50

Rev. B | Page 6 of 48

Data Sheet

ADM1293/ADM1294

SERIAL BUS TIMING CHARACTERISTICS

Table 2.

Parameter

Description

Min

Typ

Max

Unit

kHz

μs

ns

μs

f_SCLK

t_BUF

Clock frequency

Bus free time

400

1.3

0.6

300

100

1.3

0.6

20

t_HD;STA

t_SU;STA

t_SU;STO

t_HD;DAT

t_SU;DAT

t_LOW

Start hold time

Start setup time

Stop setup time

SDA hold time

SDA setup time

SCL low time

SCL high time

SCL, SDA rise time

SCL, SDA fall time

900

t_HIGH

μs

ns

1

t_R

300

t_F

20

¹t_R= (V_IL(MAX)− 0.15) to (V_IH3V3+ 0.15) and t_F= 0.9 V_DDto (V_IL(MAX)− 0.15), where V_IH3V3= 2.1 V, and V_DD= 3.3 V.

Serial Bus Timing Diagram

t_LOW

t_R

t_F

V

IH

SCL

V

IL

t_SU;STA

t_SU;DAT

t_SU;STO

t_HD;DAT

t_HD;STA

t_HIGH

V

IH

SDAO/SDAI

V

IL

t_BUF

P

S

P

Figure 3. Serial Bus Timing Diagram

Rev. B | Page 7 of 48

ADM1293/ADM1294

Data Sheet

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.

THERMAL CHARACTERISTICS

θ_JAis specified for the worst case conditions, that is, a device

soldered in a circuit board for surface-mount packages.

Table 3.

Parameter

Rating

Table 4. Thermal Resistance

VCC Pin

VSHUNT Pin

VCAP Pin

SCL Pin

SDAI Pin

SDAO Pin

ADR1 Pin

ADR2 Pin

GPO1/ALERT1/CONV Pin

GPO2/ALERT2 Pin

VIN Pin

VAUX Pin

SENSEP Pin

−0.3 V to +25 V

−0.3 V to +14 V

−0.3 V to +4 V

−0.3 V to +6.5 V

−0.3 V to VCAP + 0.3 V

−0.3 V to +25 V

−0.3 V to +4 V

−0.3 V to +25 V

30 mA

Package Type

16-Lead LFCSP

14-Lead TSSOP

θ_JA

Unit

°C/W

50.58

122.73

ESD CAUTION

SENSEN Pin

Continuous Current into VSHUNT Pin

Continuous Current into Any Other Pin

Storage Temperature Range

Operating Ambient Temperature Range

ADM1293

10 mA

−65°C to +150°C

−40°C to +105°C

Operating Junction Temperature Range

ADM1294

Junction Temperature Range

Lead Temperature, Soldering (10 sec)

Junction Temperature

−40°C to +105°C

−40°C to +110°C

300°C

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.

Rev. B | Page 8 of 48

Data Sheet

ADM1293/ADM1294

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

VCC

VCAP

ADR1

ADR2

1

2

3

4

12 SENSEP

11 SENSEN

ADM1293

TOP VIEW

10

9

NIC

(Not to Scale)

GPO2/ALERT2

1

2

3

4

5

6

7

VAUX

VCC

14

GND

13

12

11

VIN

VCAP

ADR1

ADR2

SDAI

SENSEP

SENSEN

ADM1293

TOP VIEW

(Not to Scale)

10 GPO2/ALERT2

NOTES

1. NIC = NOT INTERNALLY CONNECTED.

2. EXPOSED PAD. SOLDER THE EXPOSED PAD TO THE BOARD

TO IMPROVE THERMAL DISSIPATION. THE EXPOSED PAD CAN

BE CONNECTED TO GND.

9

8

GPO1/ALERT1/CONV

SCL

SDAO

Figure 5. ADM1293 TSSOP Pin Configuration

Figure 4. ADM1293 LFCSP Pin Configuration

Table 5. ADM1293 Pin Function Descriptions

Pin No.

LFCSP

TSSOP¹

Mnemonic

Description

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

4

VCAP

ADR1

Internal Regulated Supply. Place a capacitor with a value of 1 μF or greater on this pin to maintain accuracy.

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

6

5

6

7

ADR2

SDAI

SDAO

SCL

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.

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.

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

9

PMBus Serial Clock. Open-drain input. Requires an external resistive pull-up.

ALERT1

/CONV

General-Purpose Digital Output (GPO1).

GPO1/

ALERT1

Alert ( ). 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

ALERT2

General-Purpose Digital Output (GPO2).

GPO2/

NIC

ALERT2

Alert (

). 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

Not Internally Connected. This pin is not internally connected.

11

12

13

11

12

13

SENSEN

SENSEP

VIN

Negative Current Sense Input.

Positive Current Sense Input.

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

14

NIC

Not Internally Connected. This pin is not internally connected.

Chip Ground. This pin must connect to the lowest potential.

15

GND

EPAD

N/A

Exposed Pad. Solder the exposed pad to the board to improve thermal dissipation. Connect the exposed pad

to GND.

¹N/A means not applicable.

Rev. B | Page 9 of 48

ADM1293/ADM1294

Data Sheet

VSHUNT

VCAP

1

2

3

4

12 SENSEP

11 SENSEN

AD1294

TOP VIEW

10

9

ADR1

NIC

(Not to Scale)

ADR2

GPO2/ALERT2

1

2

3

4

5

6

7

VAUX

VSHUNT

VCAP

14

13

12

11

VEE

VIN

SENSEP

SENSEN

ADM1294

TOP VIEW

(Not to Scale)

ADR1

ADR2

10 GPO2/ALERT2

NOTES

1. NIC = NOT INTERNALLY CONNECTED.

2. EXPOSED PAD. SOLDER THE EXPOSED PAD TO THE BOARD

TO IMPROVE THERMAL DISSIPATION. THE EXPOSED PAD CAN

BE CONNECTED TO VEE.

9

8

SDAI

GPO1/ALERT1/CONV

SCL

SDAO

Figure 6. ADM1294 LFCSP Pin Configuration

Figure 7. ADM1294 TSSOP Pin Configuration

Table 6. ADM1294 Pin Function Descriptions

Pin No.

LFCSP

TSSOP¹

Mnemonic

Description

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

4

VCAP

ADR1

Internal Regulated Supply. Place a capacitor with a value of 1 μF or greater on this pin to maintain accuracy.

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

6

5

6

7

ADR2

SDAI

SDAO

SCL

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.

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.

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

9

PMBus Serial Clock. Open-drain input. Requires an external resistive pull-up.

ALERT1

General-Purpose Digital Output (GPO1).

GPO1/

/CONV

ALERT1

Alert (

). 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

ALERT2

General-Purpose Digital Output (GPO2).

GPO2/

NIC

ALERT2

Alert (

). 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.

Not Internally Connected. This pin is not internally connected.

Negative Current Sense Input.

10

11

12

13

N/A

11

SENSEN

SENSEP

VIN

12

Positive Current Sense Input.

13

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

14

NIC

Not Internally Connected. This pin is not internally connected.

Chip Ground Pin. This pin must connect to the lowest potential.

15

VEE

EPAD

N/A

EPAD

Exposed Pad. Solder the exposed pad to the board to improve thermal dissipation. Connect the exposed pad

to VEE.

¹N/A means not applicable.

Rev. B | Page 10 of 48

Data Sheet

ADM1293/ADM1294

TYPICAL PERFORMANCE CHARACTERISTICS

3.5

120

100

80

60

40

20

0

VCC = 20V

3.0

2.5

ISENSEP

ISENSEN

2.0

ADM1293

ADM1294

1.5

1.0

0.5

0

5

10

15

20

0

5

10

15

20

VCC/VSHUNT VOLTAGE (V)

VOLTAGE ON SENSEx PINS (V)

Figure 8. I_CCvs. Pin Voltages

Figure 11. ADM1293 SENSEP/SENSEN Pins Input Current vs.

SENSEP and SENSEN Pin Voltage

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

5

V

= V

= VCC

SENSEP

SENSEN

VCC = VSHUNT = 3.3V

4

3

2

1

0

–1

–2

–3

–4

–5

–40

–20

0

25

85

105

2.95

5.00

10.00

15.00

20.00

TEMPERATURE (°C)

VOLTAGE ON SENSEx PINS (V)

Figure 9. I_CCvs. Temperature

Figure 12. ADM1293 Total SENSEP and SENSEN Pins Input Current vs.

SENSEP and SENSEN Pin Voltage

14.0

1.0

V

= V

= VCC/VSHUNT

SENSEP

SENSEN

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

13.5

13.0

12.5

12.0

11.5

11.0

10.5

10.0

VSHUNT AT I = 30mA

IN

VSHUNT AT I = 3.3mA

IN

–40

–20

0

25

85

105

–40

–20

0

25

85

105

TEMPERATURE (°C)

Figure 10. VSHUNT Regulation Voltage vs. Temperature

Figure 13. Total SENSEP and SENSEN Input Current vs. Temperature

Rev. B | Page 11 of 48

ADM1293/ADM1294

Data Sheet

80

8

6

60

40

I

RANGE = 0V TO 1.2V

DISABLED

VIN

4

V

= 0V

= 12V

SENSEP

20

I

RANGE = 0V TO 1.2V

DISABLED

VAUX

2

0

–20

–40

–60

–80

–2

–4

–6

0

2

4

6

8

10

12

14

16

18

20

–200

–150

–100

–50

0

50

(mV)

100

150

200

VOLTAGE ON VIN AND VAUX PINS (V)

V

– V

SENSEN

SENSEP

Figure 17. VIN/VAUX Input Currents vs. VIN/VAUX Voltage

Figure 14. SENSEP and SENSEN Pins Input Current Imbalance vs. SENSEP and

SENSEN Pins Differential Voltage

10

5

4

8

6

VCC = V

= 3.3V

SENSEP

– V

3

2

V

= 20mV

SENSEP

SENSEN

4

2

1

0

–2

–4

–6

–8

–10

–1

–2

–3

–4

–5

VIN = 12V, RANGE = 21V, UNIT: µA

VIN = 0.6V, RANGE=1.2V, UNIT: nA

VAUX = 0.6V, SAMPLING ENABLED, UNIT: nA

VAUX = 0.6V, SAMPLING DISABLED, UNIT: nA

–40

–10

20

50

80

–40

–20

0

25

85

105

TEMPERATURE (°C)

Figure 18. VIN/VAUX Input Currents vs. Temperature

Figure 15. SENSEN and SENSEP Input Current Imbalance vs. Temperature

12

11

10

9

4.5

GRADE A, T = −40°C TO +105°C

A

GRADE B, T = −40°C TO +105°C

A

3.5

2.5

8

7

6

5

1.5

4

3

0.5

2

1

0

–0.5

0

5

10

15

20

25

0

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20

CURRENT SENSE VOTLAGE (mV)

VOLTAGE ON VIN PIN (V)

Figure 19. Worst Case Current Sense Error vs. Current Sense Voltage with

128 Sample Averaging, V_SENSEP= 0 V to 18 V, over Full Operating

Temperature Range

Figure 16. VIN Input Current vs. VIN Pin Voltage, V_RANGE= 0 V to 7.4 V

or 0 V to 21 V

Rev. B | Page 12 of 48

Data Sheet

ADM1293/ADM1294

11 DECODE

00 DECODE

3.0

01 DECODE

10 DECODE

2.5

2.0

1.5

1.0

0.5

0

2.5

2.0

1.5

1.0

0.5

0

GPO1

GPO2

–25

–20

–15

–10

(µA)

–5

0

5

0

2

4

6

8

10

12

I

ADRx

SINK CURRENT (mA)

Figure 20. V_ADRxvs. I_ADRx

Figure 21. GPOx Output Low Voltage vs. Sink Current

Rev. B | Page 13 of 48

ADM1293/ADM1294

Data Sheet

THEORY OF OPERATION

POWERING THE ADM1294

POWERING THE ADM1293

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.

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).

RTN

R

SHUNT

VSHUNT

0.1µF

VIN

R

12V

SENSE

LOAD

ADM1294

VEE

SENSEP

SENSEN

SENSEP

R

SENSE

–48V

VIN

LOAD

ADM1293

VCC

Figure 25. Powering the ADM1294 in a −48 V System

0.1µF

The shunt regulator also maintains a stable supply voltage

during transient events on the input supply, protecting the

ADM1294 from experiencing overvoltage stress.

GND

Figure 22. Powering the ADM1293 from a Monitoring Rail

Shunt Current Limiting Resistor Selection

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.

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

V _{INPUT _ MIN}– V_{OP4 _ MIN}

R

SENSE

3.3V

R_{SHUNT _ MAX}

=

I _{CC4 _ MAX}

SENSEP

SENSEN

22Ω

where:

_{INPUT_MIN}is the minimum supply input voltage before the

current limiting resistor.

_{OP4_MIN}is the minimum operating voltage of the ADM1294.

_{CC4_MAX}is the maximum supply current of the ADM1294.

VIN

V

LOAD

ADM1293

VCC

0.1µF

V

I

GND

Figure 23. Transient Glitch Protection Using an RC Network

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 R_{SHUNT_MAX}value, and as a

result, extends the range of the suitable current limiting resistors.

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.

R

SENSE

1V

SENSEP

VIN

SENSEN

LOAD

ADM1293

VCC

3.3V

0.1µF

GND

Figure 24. Powering the ADM1293 from a Separate Supply

Rev. B | Page 14 of 48

Data Sheet

ADM1293/ADM1294

Calculate the current limiting resistance lower limit by

The worst case power dissipation across the current limiting

resistor is

V_{INPUT _ MAX}– V_{SHUNT _ MAX}

2

R_{SHUNT _ MIN}

=

(

V_{INPUT _ MAX}– V_{SHUNT _ MIN}

)

P

=

I _{SHUNT _ MAX}

R_WORST

R_SHUNT

2

where:

_{INPUT_MAX}is the maximum supply input voltage before the

current limiting resistor.

_{SHUNT_MAX}is the maximum shunt regulation voltage of the

ADM1294.

_{SHUNT_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.

(

75 V – 11.5 V

)

=

= 0.54 W

V

7.5 kΩ

The user may need multiple resistors in series or in parallel to

meet the power level that is required.

V

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.

I

P

DISS _ MAX

I_{SHUNT _ MAX}

=

V_{INPUT _ MIN}– V_{OP4 _ MIN}

160 V – 2.95 V

3.6 mA

V_{SHUNT _ MAX}

R_{SHUNT _ MAX}

=

= 43.6 kΩ

I _{CC4 _ MAX}

and

T_JMAX– T _AMAX

110°C – 105°C

50.58°C

T_{J _ MAX}– T_{A _ MAX}

P_{DISS _ MAX}

=

= 0.1 W

P

=

DISS _ MAX

θ _JA

θ_JA

where:

P_{DISS _ MAX}

0.1 W

13 V

I _{SHUNT _ MAX}

=

= 7.7 mA

T

_{J_MAX}is the maximum junction temperature of the ADM1294.

_{A_MAX}is the maximum ambient temperature of the system.

V_{SHUNT _ MAX}

θ_JAis the junction to ambient thermal resistance of the ADM1294.

V_{INPUT _ MIN}– V_{SHUNT _ MAX}

200 V –13 V

R_{SHUNT _ MIN}

=

= 24.3 kΩ

I_{SHUNT _ MAX}

7.7 mA

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.

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:

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.

2

(

V_{INPUT _ MAX}– V_{SHUNT _ MIN}

)

P

=

R_WORST

R_SHUNT

2

(

200 V – 11.5 V

)

V_{INPUT_MIN}– V_{OP 4 _MIN}

35 V – 2.95 V

3.6 mA

=

= 0.91 W

39 kΩ

R_{SHUNT_MAX}

P_{DISS _ MAX}

I _{SHUNT _ MAX}

R_{SHUNT _ MIN}

=

= 8.9 kΩ

I _{CC 4 _MAX}

T_JMAX– T _AMAX

The user may need multiple resistors in series or in parallel to

meet the power level that is required.

110°C – 85°C

50.58°C

=

= 0.494 W

Additional Options of Powering the ADM1294

θ _JA

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.

P_{DISS _ MAX}

0.494 W

13 V

=

= 38 mA

V_{SHUNT _ MAX}

V_{INPUT _ MIN}– V_{SHUNT _ MAX}

75 V –13 V

38 mA

VIN

=

=1.63 kΩ

I _{SHUNT _ MAX}

R

R1

M1

Z

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.

VSHUNT

0.1µF

5.6V

ADM1294

VEE

Figure 26. Powering the ADM1294 Through a Source Follower Circuit

Rev. B | Page 15 of 48

ADM1293/ADM1294

Data Sheet

R

SENSE

12V

In this circuit, R_Zlimits 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

3.3V

SENSEP

VIN

SENSEN

VAUX

ADM1293

P

_{FET_WORST}= (V_{INPUT_MAX}− V_ZENER+ V_TH) × I_{CC4_MAX}

where:

Figure 28. Power Monitor Input Filters for the ADM1293

V

_{INPUT_MAX}is the maximum supply input voltage before the

3.3V

(REFERENCE TO –48V)

RTN

current limiting resistor.

V

_ZENERis the Zener diode reverse breakdown voltage.

_THis the threshold of the NMOSFET or base to emitter voltage

VIN

VAUX

ADM1294

in the case of an NPN emitter follower.

I_{CC4_MAX}is the maximum supply current of the ADM1294.

SENSEN

SENSEP

Another option to supply power to the ADM1294 is to use the

–48V

ADM3260 I²C and a power isolator, as shown in Figure 27.

R

SENSE

–48V

RTN

Figure 29. Power Monitor Input Filters for the ADM1294

3.3V/5V_ISO

ADM3260

2

POWER + I C

VSHUNT

POWER MONITOR

ISOLATOR

3.3V/5V

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.

VISO

VIN

ADM1294

SDAO

SDAI

SCL

SDA

SCL

SDA1

SDA2

SCL2

GNDP

PROCESSOR

SCL1

GNDISO

VEE

–48V

Figure 27. Powering the ADM1294 Using the ADM3260 I²C and Power

Isolator

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.

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.

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 2^N, where N is in the range of 0 to 7.

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.

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

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.

12 × 10 + 12.08 × 10.8

= 125.232 W

2

Not 12.04 × 10.4 = 125.216 W.

Rev. B | Page 16 of 48

Data Sheet

ADM1293/ADM1294

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: ±±2 mV, ±25 mV,

±ꢀ55 mV, and ±±55 mV. Operating closer to the full range

results in higher current measurement accuracy and higher

insertion loss across the sense resistor.

ALERTꢀ

When the GPOꢀ/

mode, an external hardware signal triggers the single shot

sampling of one or more parts at the same time.

/CONV pin is set to convert (CONV)

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.

The power monitor voltage sensing input, VIN, has three

selectable input ranges: 5 V to ꢀ.± V, 5 V to 7.6 V, and 5 V to

±ꢀ V. Configuring the VIN pin to the 5 V to ꢀ.± 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 5 V to ꢀ.± V voltage monitoring range. Both

the current and voltage sensing ranges can be configured using

the PMON_CONFIG command.

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.

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 ADMꢀ±93/ADMꢀ±94

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 I^±C 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.

Table 7. ADM1293 and ADM1294 Model Options

Model

Build in Shunt Regulator

Monitoring Accuracy Grade

Energy Meter Implementation

Custom

ADM1293-1A

ADM1293-1B

ADM1294-1A

ADM1294-1B

ADM1293-2A

ADM1294-2A

No

Yes

No

Yes

A

B

A

B

A

PMBus Standard

Rev. B | Page 17 of 48

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.

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.

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.

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

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.

Low

Connect to GND

Resistor

High-Z

High

150 kΩ resistor to GND

No connection (floating)

Connect to VCAP

Table 9. Setting I²C Addresses via the ADR1 Pin and the ADR2 Pin

Base Address

(Binary)

ADR2 Pin State

Ground

Resistor to ground Ground

Resistor to ground Resistor to ground

Resistor to ground Floating

Resistor to ground High

Floating

High

ADR1 Pin State

Ground

Resistor to ground

Floating

ADR2 Logic State

ADR1 Logic State

Address (Binary)¹

0110000X

0110001X

0110010X

0110011X

0110100X

0110101X

0110110X

0110111X

0111000X

0111001X

0111010X

0111011X

0111100X

0111101X

0111110X

0111111X

Address (Hex)

0x30

0x31

0x32

0x33

0x34

0x35

0x36

0x37

011

00

01

10

00

01

10

11

00

01

10

11

00

01

10

11

00

01

10

11

High

Ground

Resistor to ground 10

Floating

High

Ground

Resistor to ground 11

Floating

High

0x38

0x39

10

11

0x3A

0x3B

0x3C

0x3D

0x3E

High

11

0x3F

¹X means don’t care.

Rev. B | Page 18 of 48

Data Sheet

ADM1293/ADM1294

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 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

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.

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.

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

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.

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

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.

A

.

for the last byte read is a Logic 1, indicated by

S

SLAVE ADDRESS

W

A

DATA BYTE

A

P

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 30. Send Byte and Send Byte with PEC

S

SLAVE ADDRESS

R

A

DATA BYTE

A

P

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 31. Receive Byte and Receive Byte with PEC

S

SLAVE ADDRESS

W

A

COMMAND CODE

A

DATA BYTE

A

P

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 32. Write Byte and Write Byte with PEC

Rev. B | Page 19 of 48

ADM1293/ADM1294

Data Sheet

R

DATA BYTE

A

P

S

SLAVE ADDRESS

W

A

COMMAND CODE

A

SLAVE ADDRESS

Sr

A

S

SLAVE ADDRESS

W

A

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 33. Read Byte and Read Byte with PEC

A

DATA BYTE HIGH

A

P

S

SLAVE ADDRESS

W

A

COMMAND CODE

A

DATA BYTE LOW

S

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 34. Write Word and Write Word with PEC

DATA BYTE LOW

A

S

SLAVE ADDRESS

DATA BYTE HIGH

W

P

A

COMMAND CODE

A

Sr

SLAVE ADDRESS

R

A

SLAVE ADDRESS

DATA BYTE HIGH

W

COMMAND CODE

A

Sr

SLAVE ADDRESS

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 35. Read Word and Read Word with PEC

BYTE COUNT = N

A

S

SLAVE ADDRESS

DATA BYTE 1

W

A

COMMAND CODE

A

Sr

SLAVE ADDRESS

DATA BYTE N

R

A

DATA BYTE 2

A

P

SLAVE ADDRESS

DATA BYTE 1

COMMAND CODE

A

Sr

SLAVE ADDRESS

DATA BYTE N

R

DATA BYTE 2

A

PEC

A

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 36. Block Read and Block Read with PEC

ONE OR MORE DATA BYTES

S

DEVICE 1 ADDRESS

DEVICE 2 ADDRESS

W

A

COMMAND CODE 1

COMMAND CODE 2

COMMAND CODE N

A

LOW DATA BYTE

A

HIGH DATA BYTE

A

ONE OR MORE DATA BYTES

Sr

W

A

LOW DATA BYTE

A

HIGH DATA BYTE

A

ONE OR MORE DATA BYTES

Sr

DEVICE N ADDRESS

LOW DATA BYTE

A

HIGH DATA BYTE

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 37. Group Command

ONE OR MORE DATA BYTES

S

DEVICE 1 ADDRESS

DEVICE 2 ADDRESS

DEVICE N ADDRESS

W

A

COMMAND CODE 1

COMMAND CODE 2

COMMAND CODE N

A

LOW DATA BYTE

A

HIGH DATA BYTE

A

PEC 1

PEC 2

PEC N

A

ONE OR MORE DATA BYTES

Sr

LOW DATA BYTE

A

HIGH DATA BYTE

ONE OR MORE DATA BYTES

LOW DATA BYTE

A

HIGH DATA BYTE

P

MASTER TO SLAVE

SLAVE TO MASTER

Figure 38. Group Command with PEC

Rev. B | Page 20 of 48

Data Sheet

ADM1293/ADM1294

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.

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.

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.

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)

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

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.

ALERTx

warning can be used to control the state of the

pins, or to generate a SMBALERT interrupt signal through one

ALERTx

output

of the

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.

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.

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.

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.

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.

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.

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

PMBUS_REVISION Command

The STATUS_IOUT command returns a number of bits

relating to current warnings on the monitoring rail.

The PMBUS_REVISION command reports the version of Part I

and Part II of the PMBus standard.

STATUS_MFR_SPECIFIC Command

MFR_ID, MFR_MODEL, and MFR_REVISION Commands

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.

The MFR_ID, MFR_MODEL, and MFR_REVISION commands

return ASCII strings that facilitate detection and identification

of the ADM1293/ADM1294 on the bus.

Rev. B | Page 21 of 48

ADM1293/ADM1294

Data Sheet

CLEAR_FAULTS Command

The following quantities are then calculated:

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.

•

Input power (PIN)

Energy flow in forward direction (EIN)

Energy flow in reverse direction (EOUT)

PMON_CONFIG Command

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.

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

GPOX AND ALERTx PIN SETUP COMMANDS

Two multipurpose pins are provided on the ADM1293/

ALERT1

ALERT2

.

ADM1294: GPO1/

/CONV and GPO2/

These pins can be configured over the PMBus in one of three

output modes, as follows:

•

General-purpose digital output

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.

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.

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

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.

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).

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

ALERT1

digital comparator mode. The GPO1/

/CONV and

ALERT2

GPO2/

pins must be configured in SMBALERT or

digital comparator mode in the DEVICE_CONFIG register.

The input voltage measurement from the SENSEP pin is also

enabled by default. The auxiliary input voltage present on the

VAUX pin is available if enabled with the PMON_CONFIG

command.

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

READ_PIN, READ_PIN_EXT, READ_EIN, and

READ_EIN_EXT 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 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.

The power monitor can measure the following quantities:

•

Input voltage (VIN)

Output current (IOUT)

Auxiliary input voltage (VAUX)

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.

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.

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.

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, 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.

READ_EIN and READ_EOUT Commands in the PMBus

Standard

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.

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.

Each time a power calculation is performed, the 24-bit power

value is added to a corresponding unsigned 24-bit energy

accumulator register.

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.

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.

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.

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.

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 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.

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.

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 P_IN

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.

Rev. B | Page 23 of 48

ADM1293/ADM1294

Data Sheet

PEAK_VIN, PEAK_VAUX, MIN_IOUT, MAX_IOUT,

MIN_PIN, and MAX_PIN Commands

VAUX_OV_WARN_LIMIT and VAUX_UV_WARN_LIMIT

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 VAUX_OV_WARN_LIMIT and VAUX_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 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.

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.

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.

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.

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.

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.

All comparisons performed by the power monitor require the

measured value to be strictly greater or less than the threshold

value.

Y = (mX + b) × 10^R

X = 1/m × (Y × 10^−R− b)

(1)

(2)

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.

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.

VIN_OV_WARN_LIMIT and VIN_UV_WARN_LIMIT

Commands

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.

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.

Rev. B | Page 24 of 48

Data Sheet

ADM1293/ADM1294

Table 10. PMBus Conversion to Real-World Coefficients

Coefficients

Voltage Range (V)¹

0 to 1.2

0 to 7.4

0 to 21

N/A

Current Sense Range (mV)¹

m²

b

R

Voltage (V)

N/A

25

3333

5552

19,604

−1

0

−5

−50

−1

−2

−3

−1

−2

−3

−2

−3

Current (A)

Power (W)

8000 × R_SENSE

4000 × R_SENSE

20,000 × R_SENSE

10,000 × R_SENSE

10,417 × R_SENSE

5208 × R_SENSE

26,042 × R_SENSE

13,021 × R_SENSE

17,351 × R_SENSE

8676 × R_SENSE

4338 × R_SENSE

21,689 × R_SENSE

6126 × R_SENSE

30,631 × R_SENSE

15,316 × R_SENSE

7658 × R_SENSE

−100

−1000

50

100

200

25

0 to 1.2

0 to 7.4

0 to 21

0

50

100

200

25

50

100

200

25

50

100

200

¹N/A means not applicable.

²The 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.

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 mV.

To convert this value to the current flowing, use Equation 2, with

m = 4000 × 1.

Example 1: IOUT_OC_WARN_LIMIT requires a current-limit

value expressed in direct format.

X = 1/4000 × (125 × 10²+ 100)

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.

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.

Using Equation 1, and expressing X in units of amperes,

Y = ((16,000 × 10) –100) × 10⁻²

Y = 1599

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 mV.

Writing a value of 1599 with the IOUT_OC_WARN_LIMIT

command sets an overcurrent warning at 10 A.

To convert this value to the current flowing, use Equation 2, with

m = 6126 × 0.25 = 1531.5

Example 2: IOUT_OC_WARN_LIMIT requires a current-limit

value expressed in direct format.

X = 1/1531.5 × (12635 × 10²− 0)

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.

X = 825 W

This means that, when READ_PIN returns a value of 12,635,

825 W is being delivered on the rail.

Using Equation 1, and expressing X in units of amperes,

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.

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.

ENERGY METER VALUE CONVERSION

The data returned from the first read is

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.

•

SAMPLE_COUNT: 0x004000

EIN_ROLLOVER_COUNT: 0x1A

EIN_ENERGY_COUNT: 0x02FE

The data returned from the second read is

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.

•

SAMPLE_COUNT: 0x00602C

EIN_ROLLOVER_COUNT: 0xF8

EIN_ENERGY_COUNT: 0x2FDC

The data returned from the first read is

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.

•

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

Start by determining the total power accumulated in the energy

meter register at each read.

Total Power = RolloverCount × MaximumEnergyCount +

EnergyCount

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.

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.

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

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

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

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.

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 = 1/1531.5 × (884 × 10²− 0)

X = 115.38 W

X = 57.72 W

The energy consumed between the two reads is equal to the

average power by time.

The energy consumed between the two reads is equal to the

average power by time.

Energy = 115.38 W × 1 sec = 115.38 J

Energy = 57.72 W × 1 sec = 57.72 J

Rev. B | Page 26 of 48

Data Sheet

ADM1293/ADM1294

with the exact LSB values, somewhat more accurate numerical

conversions can be provided.

ENERGY METER VALUE TO PMBus STANDARD

DATA CONVERSION

To convert an ADC code to current in amperes, use the

following formulas:

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

V_SENSE= LSB_CURRENT

×

(

I _ADC+1

)

V_SENSE

I _OUT

=

R_SENSE

where:

_SENSE= V_SENSEP− V_SENSEN

1. Treating ENERGY_COUNT as an unsigned integer.

2. Multiply ROLLOVER_COUNT by 2.

V

.

LSB_CURRENTis the size of the current sense voltage LSB for a given

current sense range.

VOLTAGE AND CURRENT CONVERSION USING

LSB VALUES

I_ADCis the 12-bit ADC code.

I_OUTis the measured current value in amperes.

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.

R

_SENSEis the value of the sense resistor in ohms.

To convert an ADC code to a voltage, use the following formula:

V_M= LSB_VOLTAGEV _ADC+ 0.5

where:

V_Mis the measured value in volts.

×

(

)

LSB_VOLTAGEis the size of the voltage sensing LSB for a given input

voltage range.

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,

V_ADCis the 12-bit ADC code.

Table 11. LSB Values

LSB Type

Voltage Range (V)¹

Current Sense Range (mV)¹

LSB Value

0.3

1.801

5.101

12.5

25

50

100

LSB Voltage (mV)

0 to 1.2

0 to 7.4

0 to 21

N/A

25

50

100

200

LSB Current Sensing (µV)

¹N/A means not applicable.

N/A

Rev. B | Page 27 of 48

ADM1293/ADM1294

Data Sheet

PIN BEHAVIOR

ALERTx

WARNINGS

HANDLING/CLEARING AN ALERT

The sources of a warning are defined as follows:

ALERT1

/CONV

When warnings are configured on the GPO1/

ALERT2

CML, a communications error occurred on the I²C bus

IOUT OC warning from the ADC

VIN UV warning from the ADC

or GPO2/

pins, the pin becomes active to signal an

•

interrupt to the processor. The pin is active low, unless inversion is

ALERT1 ALERT2

enabled. The GPO1/

performs the functions of an SMBALERT.

ALERT1

/CONV or GPO2/

signal

VIN OV warning from the ADC

ALERT2

pins

Note that the GPO1/

/CONV and GPO2/

VAUX UV warning from the ADC

VAUX OV warning from the ADC

PIN overpower (OP) warning from the VIN × IOUT

calculation

can become active independently but they are always made

inactive together.

A processor can respond to the interrupt in one of two ways.

•

Hysteretic output warning from the ADC

•

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

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.

ALERT1

ALERT2

GPO1/ /CONV or GPO2/

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.

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/

GPO2/

•

ALERT1

/CONV and

) that can be used to generate interrupts to a

ALERT2

host processor.

SMBus ALERT RESPONSE ADDRESS (ARA)

ALERT1

By default at power-up, the open-drain GPO1/

/CONV

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.

ALERT2

and GPO2/

outputs are high impedance; therefore, the

ALERT1

pins can be pulled high through a resistor. The GPO1/

ALERT2

CONV and GPO2/

ADM1293/ADM1294.

/

pins are disabled by default on the

Any one or more of the warnings listed in the Warnings section

can be enabled and cause an alert, making the corresponding

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.

ALERT1

ALERT2

GPO1/

default, the active state of the GPO1/

ALERT2

/CONV or GPO2/

pin active. By

ALERT1

/CONV and

GPO2/

pins are low.

ALERT2

For example, to use GPO2/

to monitor the VAUX UV

warning from the ADC, the followings steps must be performed:

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.

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 VAUX

ALERT2

UV value, the GPO2/

interrupt to a processor.

pin is pulled low, signaling an

Rev. B | Page 28 of 48

Data Sheet

ADM1293/ADM1294

EXAMPLE USE OF SMBus ARA

DIGITAL COMPARATOR MODE

The full sequence of steps that occurs when an SMBALERT is

generated and cleared is as follows:

ALERT1 ALERT2

The GPO1/ /CONV and GPO2/ 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.

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.

ALERT2

2. The GPO2/

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.

The ALERTx_CONFIG command is used, similar to the

SMBALERT configuration, to select the specific warning

ALERT1

threshold to be monitored. The GPO1/

ALERT2

/CONV or

4. If there are no other active alerts from devices with lower

GPO2/

pin then indicates if the measured value is

2

ALERT2

I C addresses, this device makes the GPO2/

above or below the threshold.

inactive (set high) during the no acknowledge bit period

after it sends its address to the host processor.

ALERT2

5. If the GPO2/

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

ALERT2

GPO2/

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

ALERT2

for a fault or warning that is enabled on the GPO2/

pin and that was not already active (equal to 1) changes

from 0 to 1, a new alert is generated, causing the

ALERT2

GPO2/

pin to become active again.

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.

1V

LOAD

SENSEP

VIN

SENSEN

GPO2/ALERT2

1

3.3V

VCC

2

GPO1/ALERT1/CONV

VCAP

ADM1293

SDAO

SDA

SCL

VAUX

GND

ADR0

ADR1

×16

12V

LOAD

SENSEP

SENSEN

VIN

1

GPO2/ALERT2

VCC

2

GPO1/ALERT1/CONV

MICRO-

VCAP

PROCESSOR

ADM1293

SDAO

SDA

2.5V

SCL

VAUX

I

V

P

E

GND

ADR0

ADR1

1

ALERT2 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

CONV IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

2

Figure 39. ADM1293 Typical Application Diagram

Rev. B | Page 30 of 48

Data Sheet

ADM1293/ADM1294

Figure 40 shows an example application circuit of the

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.

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

300V

ISOLATED

DC-TO-DC

3.3V ISO

VSHUNT ADR0 ADR1

1

GPO2 /ALERT2

EN

2

GPO1/ALERT1 /CONV

3.3V ISO

VIN

VAUX

SDAO

3.3V ISO

3.3V

ADM1294

RTD

SDAI

SCL

VCAP

ADM3260

SCL

VEE

SENSEP

SENSEN

×16

–48V RTN

ISOLATED

DC-TO-DC

–48V

ADR1

VSHUNT ADR0

–48V

3

GPO2/ALERT2

OPTOCOUPLERS

BIDIRECTONAL

BUS BUFFERS

4

VIN

GPO1/ALERT1/CONV

ADM1294

VAUX

5V

SDAO

SDAI

VCAP

SCL

VEE

SENSEP

SENSEN

–48V

1

GPO2 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

2

3

4

ALERT1 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

ALERT2 IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

CONV IS THE ACTIVE PIN FUNCTION IN THIS SETUP.

Figure 40. ADM1294 Typical Application Diagram

Rev. B | Page 31 of 48

ADM1293/ADM1294

Data Sheet

PMBus COMMAND REFERENCE

Register addresses are in hexadecimal format.

Table 12. PMBus Commands Summary

Address

0x03

0x19

0x4A

0x57

0x58

0x6B

0x78

0x79

0x7B

0x7C

0x80

0x86

0x87

0x88

0x8C

0x97

0x98

0x99

0x9A

0x9B

0xD0

0xD1

0xD2

0xD3

0xD4

0xD5

0xD6

0xD8

0xDA

0xDB

0xDC

0xDD

0xDE

0xDF

0xE3

0xE4

0xE5

0xF2

0xF3

0xF4

Name

Description

Clear faults

PMBus capability

Reset

RW

W

R

RW

R

RW

R

RW

R

CLEAR_FAULTS

CAPABILITY

IOUT_OC_WARN_LIMIT IOUT OC warning limit

Not applicable

0xB0

0x07FF

0x0FFF

0x0000

0x7FFF

0x00

0x0000

0x00

VIN_OV_WARN_LIMIT

VIN_UV_WARN_LIMIT

PIN_OP_WARN_LIMIT

STATUS_BYTE

STATUS_WORD

STATUS_IOUT

STATUS_INPUT

STATUS_MFR_SPECIFIC

READ_EIN

READ_EOUT

READ_VIN

READ_IOUT

READ_PIN

PMBUS_REVISION

MFR_ID

MFR_MODEL

MFR_REVISION

MAX_IOUT

PEAK_VIN

VIN OV warning limit

VIN UV warning limit

PIN OP warning limit

Status byte

Status word

IOUT status

Input status

Manufacturer specific status

Read EIN

Read EOUT

Read VIN

0x00

0x000000000000

0x0000

Read IOUT

Read PIN

PMBus revision

Manufacturer ID

Manufacturer model

Manufacturer revision

Maximum IOUT

Peak VIN

0x22

0x494441

0x32

0xF800

0x0000

0x01

0x0714

0x0000

0x8000

0x000000

0x0000000000000000

0x0000

0x0FFF

0x0000

0x7FF

0x7FFF

PEAK_VAUX

Peak VAUX

PMON_CONTROL

PMON_CONFIG

ALERT1_CONFIG

ALERT2_CONFIG

DEVICE_CONFIG

MAX_PIN

READ_PIN_EXT

READ_EIN_EXT

READ_VAUX

Power monitor control

Power monitor configuration

Alert 1 configuration

Alert 2 configuration

Device configuration

Maximum PIN

Read PIN (extended)

Read EIN (extended)

Read VAUX

VAUX_OV_WARN_LIMIT VAUX OV warning limit

VAUX_UV_WARN_LIMIT VAUX UV warning limit

MIN_IOUT

Minimum IOUT

Minimum PIN

Read EOUT (extended)

Hysteresis low threshold level

Hysteresis high threshold level

Hysteresis status

MIN_PIN

READ_EOUT_EXT

HYSTERESIS_LOW

HYSTERESIS_HIGH

STATUS_HYSTERESIS

0x0000000000000000

0x8000

0x7FFF

RW

R

0x00

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.

Always reads as 1. PEC is supported.

Maximum bus interface speed.

0x1

R

1

[6:5]

4

MAX_BUS_SPEED

0x1

R

01 Always reads as 01. Maximum supported bus speed is 400 kHz.

SMBALERT support.

SMBALERT_SUPPORT

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

[15:12] RESERVED

[11:0] IOUT_OC_WARN_LIMIT

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

RW

Always reads as 0000b.

Overcurrent warning threshold for the IOUT measurement,

expressed in direct format. Set to default value to disable.

0x7FF

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

[15:12] RESERVED

[11:0] VIN_OV_WARN_LIMIT

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

RW

Always reads as 0000b.

Overvoltage warning threshold for the VIN pin measurement,

expressed in direct format. Set these bits to the default value to

disable.

0xFFF

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

[15:12] RESERVED

[11:0] VIN_UV_WARN_LIMIT

Bit Name

Settings

Description

Reset

Access

Reserved

RW

Always reads as 0000b.

0x0

Undervoltage warning threshold for the VIN pin measurement,

expressed in direct format. Set these bits to the default value to

disable.

0x000

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

[7:2]

1

Bit Name

RESERVED

CML_FAULT

Settings

Description

Reset

0x00

0x0

Access

Reserved

R

Always reads as 000000b.

Communication fault. This bit is latched.

No communications error detected on the I²C/PMBus interface.

An error was detected on the I²C/PMBus interface. Errors detected

are unsupported command, invalid PEC byte, and incorrectly

structured message.

0

1

0

NONEABOVE_STATUS

None of the above. This bit is live.

0x0

R

0

1

No other active status bit reported by any other status command.

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

0x0

Access

Reserved

R

15

RESERVED

IOUT_STATUS

Always reads as 0.

14

IOUT warning. This bit is live.

0x0

0

1

There are no active status bits to be read by STATUS_IOUT.

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

1

There are no active status bits to be read by STATUS_INPUT.

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

1

There are no active status bits to be read by STATUS_MFR_SPECIFIC.

There are one or more active status bits to be read by

STATUS_MFR_SPECIFIC.

[11:8]

[7:2]

1

RESERVED

Always reads as 0000b.

0x0

0x00

0x0

Reserved

RESERVED

Duplicate of corresponding bit in STATUS_BYTE.

Reserved

CML_FAULT

R

0

NONEABOVE_STATUS

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

[7:6]

5

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

R

RESERVED

Always reads as 00b.

IOUT overcurrent warning.

IOUT_OC_WARN

0x0

0

1

No overcurrent condition on the output supply was detected by the

power monitor using the IOUT_OC_WARN_LIMIT command.

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

0x0

Access

Reserved

R

7

RESERVED

Always reads as 0.

VIN overvoltage warning.

6

VIN_OV_WARN

0x0

0

1

No overvoltage condition on the VIN pin was detected by the power

monitor using the VIN_OV_WARN_LIMIT command.

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

1

No undervoltage condition on the VIN pin was detected by the power

monitor using the VIN_UV_WARN_LIMIT command.

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]

0

RESERVED

Always reads as 0000b.

PIN overpower warning.

0x0

Reserved

R

PIN_OP_WARN

0

1

No overpower condition on the input supply detected by the power

monitor using the PIN_OP_WARN_LIMIT command.

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

Reserved

R

7

RESERVED

Always reads as 0.

VAUX overvoltage warning.

0x0

6

VAUX_OV_WARN

0

1

No overvoltage condition was detected on the VAUX pin by the power

monitor using the VAUX_OV_WARN_LIMIT command.

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

RESERVED

VAUX undervoltage warning.

No undervoltage condition was detected on the VAUX pin by the

power monitor using the VAUX_UV_WARN_LIMIT command.

An undervoltage condition was detected on the VAUX pin by the power

monitor using the VAUX_UV_WARN_LIMIT command. This bit is latched.

0x0

R

0

1

[4:0]

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 0x000000

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.

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

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

0x00

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.

[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

[15:12] RESERVED

[11:0] READ_VIN

Bit Name

Settings

Description

Reset

0x0

Access

Always reads as 0000b.

Reserved

R

Voltage measurement on the VIN pin after averaging, expressed in

direct format.

0x000

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.

PMBus Part II Support.

0010 Revision 1.2.

[3:0]

PMBUS_P2_REVISION

0x2

R

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

[15:12] RESERVED

[11:0] PEAK_VIN

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

R

Always reads as 0000b.

Reports the most positive VIN value recorded, expressed in direct

format. Writing 0 with this command resets it to the default value.

0x000

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

[15:12] RESERVED

[11:0] PEAK_VAUX

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

R

Always reads as 0000b.

Reports the most positive VAUX value recorded, expressed in direct

format. Writing 0 with this command resets it to the default value.

0x000

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

[7:1]

0

Bit Name

RESERVED

CONVERT

Settings

Description

Reset

0x00

0x1

Access

Reserved

RWAS

Always reads as 0000000b.

Convert enable.

0

1

Power monitor is not running.

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

0x0

Access

Reserved

RW

15

RESERVED

Always reads as 0.

14

SIMULTANEOUS

Simultaneous sampling mode enable.

Simultaneous sampling disabled.

Simultaneous sampling enabled.

PIN averaging mode select.

0x0

0

1

[13:11] PWR_AVG

0x0

0x7

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.

VIN/VAUX/IOUT averaging mode select.

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.

Current sense range (CSR) select.

[10:8]

VI_AVG

[7:6]

IRANGE

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

4

RESERVED

Always reads as 0.

0x0

0x1

Reserved

RW

PMON_MODE

Conversion mode select.

0

1

Single shot sampling.

Continuous sampling.

VIN Sampling mode select.

[3:2]

VIN_SEL

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.

VAUX sampling enable.

1

0

VAUX_EN

RESERVED

0x0

RW

0

1

VAUX sampling disabled.

VAUX sampling enabled.

Always reads as 0.

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/

output pin. The pin can operate in different modes, configured using the DEVICE_CONFIG command.

/CONV

ALERT1

Table 37. Bit Descriptions for ALERT1_CONFIG

Bits

Bit Name

Settings

Description

Reset

Access

Reserved

RW

[15:12] RESERVED

Always reads as 0000b.

0x0

11

10

9

CML_ERROR_EN1

Communications error enable.

IOUT overcurrent warning enable.

Hysteretic output enable.

VIN overvoltage warning enable.

VIN undervoltage warning enable.

VAUX overvoltage warning enable.

VAUX undervoltage warning enable.

Always reads as 0.

IOUT_OC_WARN_EN1

HYSTERETIC_EN1

VIN_OV_WARN_EN1

VIN_UV_WARN_EN1

VAUX_OV_WARN_EN1

VAUX_UV_WARN_EN1

RESERVED

RW

8

RW

7

RW

6

RW

5

RW

4

Reserved

RW

3

PIN_OP_WARN_EN1

RESERVED

PIN overpower warning enable.

Always reads as 000b.

[2:0]

Reserved

ALERT 2 CONFIGURATION REGISTER

Address: 0xD6, Reset: 0x0000, Name: ALERT2_CONFIG

ALERT2

The ALERT2_CONFIG command allows different combinations of faults and warnings to be configured on the GPO2/

pin. The pin can operate in different modes, configured using the DEVICE_CONFIG command.

output

Table 38. Bit Descriptions for ALERT2_CONFIG

Bits

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

RW

[15:12] RESERVED

Always reads as 0000b.

11

10

9

CML_ERROR_EN2

Communications error enable.

IOUT overcurrent warning enable.

Hysteretic output enable.

VIN overvoltage warning enable.

VIN undervoltage warning enable.

VAUX overvoltage warning enable.

VAUX undervoltage warning enable.

Always reads as 0.

IOUT_OC_WARN_EN2

HYSTERETIC_EN2

VIN_OV_WARN_EN2

VIN_UV_WARN_EN2

VAUX_OV_WARN_EN2

VAUX_UV_WARN_EN2

RESERVED

RW

8

RW

7

RW

6

RW

5

RW

4

Reserved

RW

3

PIN_OP_WARN_EN2

RESERVED

PIN overpower warning enable.

Always reads as 000b.

[2:0]

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

Reserved

RW

[15:11] RESERVED

Always reads as 0000b.

0x0

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.

0

1

Current hysteresis mode.

Power hysteresis mode.

GPO2 configuration mode.

[9:8]

GPO2_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

GPO1_MODE

GPO invert mode.

In SMBALERT mode the output is not inverted, and active low. In GPO

mode, the output is set low.

In SMBALERT mode the output is inverted, and active high. In GPO

mode, the output is set high.

0x0

RW

0

1

[6:5]

GPO1 configuration mode.

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

RESERVED

GPO1 invert mode.

In SMBALERT mode, the output is not inverted, and active low. In GPO

mode, the output is set low.

In SMBALERT mode the output is inverted, and active high. In GPO

mode, the output is set high.

0x0

RW

0

1

[3:0]

Always reads as 0000b.

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 0x000000

direct format.

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

READ VAUX REGISTER

Address: 0xDD, Reset: 0x0000, Name: READ_VAUX

The READ_VAUX command reads the auxiliary input voltage, V_{VAU X}, from the device.

Table 43. Bit Descriptions for READ_VAUX

Bits

[15:12] RESERVED

[11:0] READ_VAUX

Bit Name

Settings

Description

Reset

Access

Always reads as 0000b.

0x0

Reserved

R

Voltage measurement on VAUX pin after averaging, expressed in direct 0x000

format.

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

[15:12] RESERVED

[11:0] VAUX_OV_WARN_LIMIT

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

RW

Always reads as 0000b.

Overvoltage warning threshold for the VAUX pin measurement,

expressed in direct format. Set these bits to the default value to

disable.

0xFFF

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

0x0

Access

Reserved

RW

[15:12] RESERVED

Always reads as 0000b.

[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

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. 0x7FFF

Writing 0 with this command resets it to the default value.

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 0x0000

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.

[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

[7:4]

3

Bit Name

Settings

Description

Reset

0x0

Access

Reserved

R

RESERVED

Always reads as 0000b.

IOUT overcurrent warning.

IOUT_OC_WARN

0x0

0

1

No overcurrent condition on the output supply detected by the power

monitor using the IOUT_OC_WARN_LIMIT command.

An overcurrent condition was detected by the power monitor using the

IOUT_OC_WARN_LIMIT command.

2

1

0

HYST_STATE

Hysteretic comparison output.

Comparison output low.

Comparison output high.

0x0

R

0

1

HYST_GT_HIGH

HYST_LT_LOW

Hysteretic upper threshold comparison.

Compared value is equal or below upper threshold.

Compared value is above upper threshold.

Hysteretic lower threshold comparison.

Compared value is equal or above the lower threshold.

Compared value is below the lower threshold.

0

1

0

1

Rev. B | Page 45 of 48

ADM1293/ADM1294

Data Sheet

OUTLINE DIMENSIONS

4.10

4.00 SQ

3.90

0.35

0.30

0.25

PIN 1

INDICATOR

PIN 1

INDICATOR

13

16

0.65

BSC

12

1

EXPOSED

PAD

2.70

2.60 SQ

2.50

4

9

5

8

0.45

0.40

0.35

0.20 MIN

TOP VIEW

BOTTOM VIEW

0.80

0.75

0.70

FOR PROPER CONNECTION OF

THE EXPOSED PAD, REFER TO

THE PIN CONFIGURATION AND

FUNCTION DESCRIPTIONS

0.05 MAX

0.02 NOM

COPLANARITY

0.08

SECTION OF THIS DATA SHEET.

SEATING

PLANE

0.20 REF

COMPLIANT TO JEDEC STANDARDS MO-220-WGGC.

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

5.10

5.00

4.90

14

8

7

4.50

4.40

4.30

6.40

BSC

1

PIN 1

0.65 BSC

1.05

1.00

0.80

1.20

MAX

0.20

0.09

0.75

0.60

0.45

8°

0°

0.15

0.05

COPLANARITY

0.10

SEATING

PLANE

0.30

0.19

COMPLIANT TO JEDEC STANDARDS MO-153-AB-1

Figure 42. 14-Lead Thin Shrink Small Outline Package [TSSOP]

RU-14

Dimensions shown in millimeters

Rev. B | Page 46 of 48

Data Sheet

ADM1293/ADM1294

ORDERING GUIDE

Model¹

Temperature Range²

−40°C to +105°C

Grade

Package Description

16-Lead LFCSP_WQ

14-Lead TSSOP

16-Lead LFCSP_WQ

14-Lead TSSOP

Package Option

CP-16-17

RU-14

CP-16-17

RU-14

CP-16-17

ADM1293-1AACPZ

ADM1293-1AACPZ-RL7

ADM1293-1BACPZ

ADM1293-1BACPZ-RL7

ADM1293-1AARUZ

ADM1293-1AARUZ-RL7

ADM1293-1BARUZ

ADM1293-1BARUZ-RL7

ADM1293-2AACPZ

ADM1293-2AACPZ-RL

ADM1294-1AACPZ

ADM1294-1AACPZ-RL7

ADM1294-1BACPZ

ADM1294-1BACPZ-RL7

ADM1294-1AARUZ

ADM1294-1AARUZ-RL7

ADM1294-1BARUZ

ADM1294-1BARUZ-RL7

ADM1294-2AACPZ

ADM1294-2AACPZ-RL

EVAL-ADM1293EBZ

EVAL-ADM1294EBZ

A

B

A

B

A

B

A

B

A

16-Lead LFCSP_WQ

Evaluation Kit

¹Z = RoHS Compliant Part.

²The operation temperature is specified as ambient for ADM1293 and junction for ADM1294.

Rev. B | Page 47 of 48

ADM1293/ADM1294

NOTES

Data Sheet

I²C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).

registered trademarks are the property of their respective owners.

D11891-0-3/15(B)

Rev. B | Page 48 of 48


型号：	ADM1294-1BARUZ-RL7
厂家：	ADI
描述：	Digital Power Monitor with PMBus Interface
文件：	总48页 (文件大小：777K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

ADM1294-1BARUZ-RL7 [ADI]

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