Datasheet

ADM1275 Data Sheet
Rev. D | Page 2 of 48
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Applications Diagram ...................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 3
Specifications ..................................................................................... 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 ........................................... 14
Functional Block Diagrams ........................................................... 20
Theory of Operation ...................................................................... 21
Powering the ADM1275 ............................................................ 21
Current Sense Inputs .................................................................. 21
Current Limit Reference ............................................................ 22
Setting the Current Limit (ISET) ............................................. 22
Soft Start ...................................................................................... 23
Foldback ....................................................................................... 23
Timer ............................................................................................ 24
Hot-Swap Retry Duty Cycle ...................................................... 24
FET Gate Drive Clamps ............................................................. 24
Fast Response to Severe Overcurrent ...................................... 25
Undervoltage and Overvoltage ................................................. 25
ENABLE Input (ADM1275-3 Only) ........................................ 25
Power Good ................................................................................. 25
VOUT Measurement ................................................................. 26
FET Health .................................................................................. 26
Power Monitor ............................................................................ 26
PMBus Interface ............................................................................. 27
Device Addressing ...................................................................... 27
SMBus Protocol Usage ............................................................... 27
Packet Error Checking ............................................................... 27
Partial Transactions on I
2
C Bus ................................................ 27
SMBus Message Formats ........................................................... 28
Group Commands ..................................................................... 29
Hot-Swap Control Commands ................................................. 30
ADM1275 Information Commands ........................................ 30
Status Commands ...................................................................... 30
GPO and Alert Pin Setup Commands .................................... 31
Power Monitor Commands ...................................................... 31
Warning Limit Setup Commands ............................................ 32
PMBus Direct Format Conversion .......................................... 32
Voltage and Current Conversion using LSB values ............... 33
ADM1275 Alert Pin Behavior ...................................................... 34
Faults and Warnings .................................................................. 34
Generating an Alert ................................................................... 34
Handling/Clearing an Alert ...................................................... 34
SMBus Alert Response Address ............................................... 35
Example Use of SMBus Alert Response Address ................... 35
PMBus Command Reference ........................................................ 36
OPERATION .............................................................................. 37
CLEAR_FAULTS ........................................................................ 37
CAPABILITY .............................................................................. 37
VOUT_OV_WARN_LIMIT ..................................................... 37
VOUT_UV_WARN_LIMIT ..................................................... 37
IOUT_OC_WARN_LIMIT ...................................................... 37
IOUT_WARN2_LIMIT ............................................................. 38
VIN_OV_WARN_LIMIT ......................................................... 38
VIN_UV_WARN_LIMIT ......................................................... 38
STATUS_BYTE .......................................................................... 38
STATUS_WORD ........................................................................ 39
STATUS_VOUT ......................................................................... 39
STATUS_IOUT .......................................................................... 39
STATUS_INPUT ........................................................................ 40
STATUS_MFR_SPECIFIC ........................................................ 40
READ_VIN ................................................................................. 40
READ_VOUT ............................................................................. 41
READ_IOUT .............................................................................. 41
PMBUS_REVISION .................................................................. 41