Datasheet

LTC2974
2
2974fc
For more information www.linear.com/LTC2974
Table oF conTenTs
Features ........................................................... 1
Applications ...................................................... 1
Typical Application .............................................. 1
Description........................................................ 1
Absolute Maximum Ratings .................................... 4
Order Information ................................................ 4
Pin Configuration ................................................ 4
Electrical Characteristics ....................................... 5
PMBus Timing Diagram ......................................... 9
Typical Performance Characteristics ........................ 10
Pin Functions .................................................... 13
Block Diagram ................................................... 15
Operation......................................................... 16
LTC2974 Operation Overview ......................................... 16
EEPROM .................................................................... 17
AUXFAULTB ................................................................... 17
RESETB .......................................................................... 18
PMBus Serial Digital Interface ....................................... 18
PMBus ....................................................................... 18
Device Address .......................................................... 18
Processing Commands.............................................. 19
PMBUS Command Summary .................................. 22
Summary Table ..........................................................22
Data Formats ............................................................. 27
PMBus Command Description ................................ 28
Addressing and Write Protect ........................................28
PAGE ..........................................................................28
WRITE_PROTECT ......................................................28
WRITE-PROTECT Pin ................................................29
MFR_PAGE_FF_MASK ..............................................29
MFR_I2C_BASE_ADDRESS ......................................29
On/Off Control, Margining and Configuration ................30
OPERATION ...............................................................30
ON_OFF_CONFIG ....................................................... 31
MFR_CONFIG_LTC2974 ............................................32
Cascade Sequence ON with Time-Based
Sequence OFF ............................................................33
MFR_CONFIG2_LTC2974 ..........................................35
MFR_CONFIG3_LTC2974 ..........................................35
Tracking Supplies On and Off .................................... 37
Tracking Implementation ........................................... 38
MFR_CONFIG_ALL_LTC2974 ....................................39
Programming User EEPROM Space ...............................40
STORE_USER_ALL and RESTORE_USER_ALL ........ 41
Bulk Programming the User EEPROM Space ............ 41
MFR_EE_UNLOCK ..................................................... 41
MFR_EE_ERASE .......................................................42
MFR_EE_DATA .......................................................... 42
Response When Part Is Busy ....................................43
MFR_EE Erase and Write Programming Time ........... 43
Input Voltage Commands and Limits .............................43
VIN_ON, VIN_OFF, VIN_OV_FAULT_LIMIT, VIN_OV_
WARN_LIMIT, VIN_UV_WARN_LIMIT and
VIN_UV_FAULT_LIMIT
..............................................43
Output Voltage Commands and Limits ..........................44
VOUT_MODE .............................................................44
VOUT_COMMAND, VOUT_MAX, VOUT_MARGIN_
HIGH, VOUT_MARGIN_LOW, VOUT_OV_FAULT_LIMIT,
VOUT_OV_WARN_LIMIT, VOUT_UV_WARN_LIMIT,
V
OUT_
UV_FAULT_LIMIT, POWER_GOOD_ON and
POWER_GOOD_OFF
..................................................45
MFR_VOUT_DISCHARGE_THRESHOLD ....................45
MFR_DAC ..................................................................45
Output Current Commands and Limits ..........................46
IOUT_CAL_GAIN .......................................................46
IOUT_OC_FAULT_LIMIT, IOUT_OC_WARN_LIMIT and
IOUT_UC_FAULT_LIMIT ............................................ 47
MFR_IOUT_CAL_GAIN_TC ........................................ 47
External Temperature Commands And Limits ................48
OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_
LIMIT and UT_FAULT_LIMIT .....................................48
MFR_TEMP_1_GAIN and MFR_TEMP_1_OFFSET ......48
MFR_T_SELF_HEAT, MFR_IOUT_CAL_GAIN_TAU_INV
and MFR_IOUT_CAL_GAIN_THETA ..........................49
Sequencing Timing Limits and Clock Sharing ................ 51
TON_DELAY, TON_RISE, TON_MAX_FAULT_LIMIT
and TOFF_DELAY ....................................................... 51
MFR_RESTART_DELAY ............................................. 51
Watchdog Timer and Power Good ................................. 52
MFR_PWRGD_EN .....................................................52
Clock Sharing ............................................................52
MFR_POWERGOOD_ASSERTION_DELAY ................ 53
Watchdog Operation ..................................................53
MFR_WATCHDOG_T_FIRST and
MFR_WATCHDOG_T ..................................................53
Fault Responses ............................................................. 54
Clearing Latched Faults .............................................54
VOUT_OV_FAULT_RESPONSE and VOUT_UV_FAULT_
RESPONSE ................................................................55
IOUT_OC_FAULT_RESPONSE and IOUT_UC_FAULT_
RESPONSE ................................................................56
OT_FAULT_RESPONSE, UT_FAULT_RESPONSE,
VIN_OV_FAULT_RESPONSE and VIN_UV_FAULT_
RESPONSE ................................................................57
TON_MAX_FAULT_RESPONSE ................................. 58
MFR_RETRY_DELAY .................................................58
MFR_RETRY_COUNT ................................................ 58
Shared External Faults ...................................................59
MFR_FAULTB0_PROPAGATE and MFR_FAULTB1_
PROPAGATE ..............................................................59