Datasheet

LTC2977
3
2977fa
For more information www.linear.com/LTC2977
TABLE OF CONTENTS
MFR_FAULTB00_RESPONSE, MFR_FAULTB01_
RESPONSE, MFR_FAULTB10_RESPONSE and
MFR_FAULTB11_RESPONSE ..............................52
MFR_VINEN_OV_FAULT_RESPONSE .................53
MFR_VINEN_UV_FAULT_RESPONSE ................. 54
MFR_RETRY_COUNT ......................................... 55
MFR_RETRY_DELAY ..........................................55
MFR_RESTART_DELAY ......................................55
MFR_VOUT_PEAK ..............................................56
MFR_VIN_PEAK .................................................56
MFR_TEMPERATURE_PEAK ..............................56
MFR_DAC ...........................................................57
MFR_POWERGOOD_ASSERTION_DELAY .........57
MFR_PADS .........................................................58
MFR_SPECIAL_ID .............................................. 59
MFR_SPECIAL_LOT ........................................... 59
MFR_VOUT_DISCHARGE_THRESHOLD .............59
MFR_COMMON ..................................................60
USER_DATA_00, USER_DATA_01, USER_
DATA_02, USER_DATA_03, USER_DATA_04,
MFR_LTC_RESERVED_1 and MFR_LTC_
RESERVED_2 .....................................................60
MFR_VOUT_MIN ................................................ 61
MFR_VIN_MIN ...................................................61
MFR_TEMPERATURE_MIN ................................61
MFR_STATUS_2 .................................................62
MFR_TELEMETRY ..............................................63
Watchdog Operation ...............................................64
MFR_WATCHDOG_T_FIRST and MFR_
WATCHDOG_T ....................................................64
Bulk Programming the User EEPROM Space .......... 65
MFR_EE_UNLOCK ..............................................65
MFR_EE_ERASE ................................................66
MFR_EE_DATA ................................................... 66
Response When Part Is Busy .............................67
MFR_EE Erase and Write Programming Time ....67
Fault Log Operation ................................................67
MFR_FAULT_LOG_STORE .................................67
MFR_FAULT_LOG_RESTORE .............................67
MFR_FAULT_LOG_CLEAR ..................................68
MFR_FAULT_LOG_STATUS ................................68
MFR_FAULT_LOG ...............................................69
Applications Information ................................ 76
Overview .................................................................76
Powering the LTC2977............................................ 76
Setting Command Register Values ......................... 76
Sequence, Servo, Margin and Restart Operations ..76
Command Units On or Off .................................. 76
On Sequencing ...................................................77
On State Operation .............................................77
Servo Modes ......................................................77
DAC Modes .........................................................77
Margining ...........................................................78
Off Sequencing ...................................................78
V
OUT
Off Threshold Voltage ................................78
Automatic Restart Via MFR_RESTART_DELAY
Command and CONTROLn pin ...........................78
Fault Management .................................................. 78
Output Overvoltage and Undervoltage Faults ..... 78
Output Overvoltage and Undervoltage
Warnings ............................................................79
Configuring the V
IN_EN
Output ............................79
Multichannel Fault Management ........................ 81
Interconnect Between Multiple LTC2977’s ..............81
Application Circuits .................................................82
Trimming and Margining DC/DC Converters with
External Feedback Resistors...............................82
Four-Step Resistor Selection Procedure for DC/DC
Converters with External Feedback Resistors.....83
Trimming and Margining DC/DC Converters
with a TRIM Pin .................................................. 84
Two-Step Resistor and DAC Full-Scale Voltage
Selection Procedure for DC/DC Converters
with a TRIM Pin .................................................. 84
Measuring Current ..............................................84
Measuring Current with a Sense Resistor...........85
Measuring Current with Inductor DCR ................85
Single Phase Design Example ............................85
Measuring Multiphase Currents..........................85
Multiphase Design Example ...............................86
Anti-aliasing Filter Considerations ......................86
Sensing Negative Voltages .................................87
Connecting the DC1613 USB to I
2
C/SMBus/PMBus
Controller to the LTC2977 in System ...................... 87
Design Checklist .....................................................89
LTpowerPlay: An Interactive GUI for Power System
Managers ................................................................89
PCB Assembly and Layout Suggestions .................90
Bypass Capacitor Placement ..............................90
Exposed Pad Stencil Design ...............................90
PC Board Layout.................................................91
Unused ADC Sense Inputs ..................................91
Package Description ..................................... 92
Revision History .......................................... 93
Typical Application ....................................... 94
Related Parts .............................................. 94