Datasheet

LTC2978A
3
2978afa
For more information www.linear.com/LTC2978A
TABLE OF CONTENTS
MFR_VINEN_OV_FAULT_RESPONSE .................48
MFR_VINEN_UV_FAULT_RESPONSE ................. 49
MFR_RETRY_DELAY ..........................................49
MFR_RESTART_DELAY ......................................50
MFR_VOUT_PEAK .............................................. 50
MFR_VIN_PEAK .................................................50
MFR_TEMPERATURE_PEAK ..............................50
MFR_DAC ........................................................... 51
MFR_POWERGOOD_ASSERTION_DELAY ......... 51
Watchdog Operation ............................................... 51
MFR_WATCHDOG_T_FIRST and MFR_
WATCHDOG_T .................................................... 51
MFR_PAGE_FF_MASK .......................................52
MFR_PADS .........................................................53
MFR_I2C_BASE_ADDRESS ...............................53
MFR_SPECIAL_ID ..............................................53
MFR_SPECIAL_LOT ...........................................54
MFR_VOUT_DISCHARGE_THRESHOLD .............54
MFR_COMMON .................................................. 54
MFR_SPARE_0, MFR_SPARE_1, MFR_SPARE_2,
MFR_SPARE_3 ..................................................54
MFR_VOUT_MIN ................................................55
MFR_VIN_MIN ...................................................55
MFR_TEMPERATURE_MIN ................................55
Fault Log Operation ................................................55
MFR_FAULT_LOG_STORE .................................56
MFR_FAULT_LOG_RESTORE ............................. 56
MFR_FAULT_LOG_CLEAR ..................................56
MFR_FAULT_LOG_STATUS ................................56
MFR_FAULT_LOG ...............................................57
Applications Information ................................ 63
Overview .................................................................63
Powering the LTC2978A .........................................63
Setting Command Register Values .........................63
Sequence, Servo, Margin and Restart Operations ..63
Command Units On or Off ..................................63
On Sequencing ...................................................64
On State Operation .............................................64
Servo Modes ......................................................64
DAC Modes .........................................................65
Margining ...........................................................65
Off Sequencing ................................................... 65
V
OUT
Off Threshold Voltage ................................ 65
Automatic Restart Via MFR_RESTART_DELAY
Command and CONTROLn pin ...........................66
Fault Management ..................................................66
Output Overvoltage and Undervoltage Faults .....66
Output Overvoltage and Undervoltage Warnings 66
Configuring the V
IN_EN
Output ............................66
Multichannel Fault Management ........................67
Interconnect Between Multiple LTC2978As ............69
Application Circuits .................................................70
Trimming and Margining DC/DC Converters with
External Feedback Resistors...............................70
Four-Step Resistor Selection Procedure for DC/DC
Converters with External Feedback Resistors.....71
Trimming and Margining DC/DC Converters with a
TRIM Pin ............................................................72
Two-Step Resistor and DAC Full-Scale Voltage
Selection Procedure for DC/DC Converters with a
TRIM Pin ............................................................72
Measuring Current ..............................................72
Measuring Current with a Sense Resistor...........73
Measuring Current with Inductor DCR ................73
Single Phase Design Example ............................ 74
Measuring Multiphase Currents.......................... 74
Multiphase Design Example ............................... 74
Anti-aliasing Filter Considerations ...................... 75
Sensing Negative Voltages .................................75
Connecting the DC1613 USB to I
2
C/SMBus/PMBus
Controller to the LTC2978A in System ....................76
LTpowerPlay: An Interactive GUI for Power System
Managers ................................................................78
PCB Assembly and Layout Suggestions .................79
Bypass Capacitor Placement ..............................79
Exposed Pad Stencil Design ............................... 79
PC Board Layout.................................................79
Unused ADC Sense Inputs ..................................79
Package Description ..................................... 80
Revision History .......................................... 81
Typical Application ....................................... 82
Related Parts .............................................. 82