LTC2978A
8-Channel PMBus Power
NOT RECOMMENDED FOR NEW DESIGNS
Please See LTC2977 for Replacement
System Manager Featuring Accurate
Output Voltage Measurement
FEATURES DESCRIPTION
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Sequence, Trim, Margin and Supervise Eight Power Supplies The LTC 2978A is an 8-channel Power System Manager
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Manage Faults, Monitor Telemetry and Create Fault Logs used to sequence, trim (servo), margin, supervise, man-
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PMBus Compliant Command Set age faults, provide telemetry and create fault logs. PMBus
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Supported by LTpowerPlay GUI commands support power supply sequencing, precision
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Margin or Trim Supplies to 0.25% Accuracy point-of-load voltage adjustment and margining. DACs use
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Fast OV/UV Supervisors per Channel a proprietary soft-connect algorithm to minimize supply
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Coordinate Sequencing and Fault Management disturbances. Supervisory functions include overvoltage
Across Multiple Chips and undervoltage threshold limits for eight power supply
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Automatic Fault Logging to Internal EEPROM output channels and one power supply input channel, as
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Operate Autonomously without Additional Software well as over and under temperature limits. Programmable
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Internal Temperature and Input Voltage Supervisors fault responses can disable the power supplies with optional
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Accurate Monitoring of Eight Output Voltages, Input retry after a fault is detected. Faults that disable a power
Voltage and Internal Die Temperature supply can automatically trigger black box EEPROM storage
2
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I C/SMBus Serial Interface of fault status and associated telemetry. An internal 16-bit
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Can Be Powered from 3.3V, or 4.5V to 15V ADC monitors eight output voltages, one input voltage,
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Programmable Watchdog Timer and die temperature. In addition, odd numbered chan-
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100% Compatible with the LTC2978 nels can be configured to measure the voltage across a
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Available in 64-pin 9mm 9mm QFN Package current sense resistor. A programmable watchdog timer
monitors microprocessor activity for a stalled condition and
resets the microprocessor if necessary. A single wire bus
APPLICATIONS
synchronizes power supplies across multiple ADI power
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Computers and Network Servers
system management devices. Configuration EEPROM sup-
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Industrial Test and Measurement
ports autonomous operation without additional software.
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High Reliability Systems
All registered trademarks and trademarks are the property of their respective owners. Protected
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Medical Imaging
by U.S. Patents including 7382303, 7420359 and 7940091.
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Video
TYPICAL APPLICATION
Typical ADC Total Unadjusted
8-Channel PMBus Power System Manager Error vs Temperature
0.035
4.5V < V < 15V** V
IBUS IN ADC V = 1.8V
IN
0.030
V V V
PWR IN_SNS
OUT
3.3V**
V V DIGITALLY
DD33 DACP0
0.025
MANAGED
V R30
TO INTERMEDIATE SENSEP0
V POWER
IN_EN
BUS CONVERTER ENABLE R20
SUPPLY
0.020
LTC2978A*
SDA V
LOAD FB
SCL V 0.015
PMBus DACM0 R10
INTERFACE
ALERTB V SGND
SENSEM0
0.010
CONTROL0 V RUN/SS
OUT_EN0
GND
0.005
WRITE-PROTECT WP PWRGD TO P RESETB INPUT
WDI/RESETB
WATCHDOG 0
100
TIMER INTERRUPT 50 35 20 5 10 25 40 55 70 85
TO/FROM OTHER FAULTB00 ASEL0
TEMPERATURE (C)
LTC2978s
SHARE_CLK ASEL1
*SOME DETAILS OMITTED FOR CLARITY
2978a TA01b
ONLY ONE OF EIGHT CHANNELS SHOWN
GND
2978a TA01a
**LTC2978A MAY BE POWERED FROM EITHER AN
EXTERNAL 3.3V SUPPLY OR THE INTERMEDIATE BUS
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For more information www.linear.com/LTC2978A
ERROR (%)LTC2978A
TABLE OF CONTENTS
Features ..................................................... 1 Input Voltage Related Commands ...........................34
Applications ................................................ 1 VIN_ON, VIN_OFF, VIN_OV_FAULT_LIMIT, VIN_
Typical Application ........................................ 1 OV_WARN_LIMIT, VIN_UV_WARN_LIMIT and
Description.................................................. 1 VIN_UV_FAULT_LIMIT .......................................34
Absolute Maximum Ratings .............................. 4 Temperature Related Commands ............................35
Order Information .......................................... 4 OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_
Pin Configuration .......................................... 4 LIMIT and UT_FAULT_LIMIT ...............................35
Electrical Characteristics ................................. 5 Timer Limits ...........................................................35
PMBus Timing Diagram ................................... 9 TON_DELAY, TON_RISE, TON_MAX_FAULT_
Typical Performance Characteristics .................. 10 LIMIT and TOFF_DELAY......................................35
Pin Functions .............................................. 15 Fault Response for Voltages Measured by the High
Block Diagram ............................................. 17 Speed Supervisor ...................................................36
Operation................................................... 18 VOUT_OV_FAULT_RESPONSE and VOUT_UV_
Operation Overview ................................................ 18 FAULT_RESPONSE .............................................36
EEPROM ............................................................. 18 Fault Response for Values Measured by the ADC ...37
Reset ...................................................................... 19 OT_FAULT_RESPONSE, UT_FAULT_RESPONSE,
Write-Protect Pin .................................................... 19 VIN_OV_FAULT_RESPONSE and VIN_UV_FAULT_
Other Operations .................................................... 19 RESPONSE .........................................................37
Clock Sharing ..................................................... 19
Timed Fault Response ............................................37
PMBus Serial Digital Interface ................................20
TON_MAX_FAULT_RESPONSE ..........................37
PMBus ................................................................20
Status Commands ..................................................38
Device Address ...................................................23
STATUS_BYTE ....................................................38
Processing Commands ....................................... 24
STATUS_WORD ..................................................39
Summary Table ...................................................25
STATUS_VOUT ...................................................39
PMBus Command Summary ............................ 25
STATUS_INPUT ..................................................40
Data Formats ......................................................29
STATUS_TEMPERATURE ....................................40
PMBus Command Description .......................... 30
STATUS_CML ..................................................... 41
Operation, Mode and EEPROM Commands ............30
STATUS_MFR_SPECIFIC .................................... 41
PAGE ..................................................................30
ADC Monitoring Commands ...................................42
OPERATION ........................................................31
READ_VIN ..........................................................42
ON_OFF_CONFIG ................................................32
READ_VOUT .......................................................42
CLEAR_FAULTS..................................................32
READ_TEMPERATURE_1 ..................................42
WRITE_PROTECT ...............................................33
PMBUS_REVISION .............................................42
STORE_USER_ALL and RESTORE_USER_ALL .33
Manufacturer Specific Commands ..........................43
CAPABILITY ........................................................ 33
MFR_CONFIG_LTC2978 .....................................43
VOUT_MODE ......................................................34
MFR_CONFIG_ALL_LTC2978 ............................44
Output Voltage Related Commands ........................34
MFR_FAULTBz0_PROPAGATE, MFR_FAULTBz1_
VOUT_COMMAND, VOUT_MAX, VOUT_MARGIN_
PROPAGATE .......................................................45
HIGH, VOUT_MARGIN_LOW, VOUT_OV_FAULT_
MFR_PWRGD_EN ..............................................46
LIMIT, VOUT_OV_WARN_LIMIT, VOUT_UV_
MFR_FAULTB00_RESPONSE, MFR_FAULTB01_
WARN_LIMIT, VOUT_UV_FAULT_LIMIT, POWER_
RESPONSE, MFR_FAULTB10_RESPONSE and
GOOD_ON and POWER_GOOD_OFF ..................34
MFR_FAULTB11_RESPONSE .............................. 47
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For more information www.linear.com/LTC2978A