Datasheet

LTC2974
56
2974fc
For more information www.linear.com/LTC2974
IOUT_OC_FAULT_RESPONSE and IOUT_UC_FAULT_RESPONSE
The fault response documented here is for currents that are measured by the high speed supervisor. These currents
are measured over a short period of time and may require a deglitch period. Note that in addition to the response
described by these commands, the LTC2974 will also:
• Set the appropriate bit in the STATUS_BYTE.
• Set the appropriate bit in the STATUS_WORD.
• Set the appropriate bit in the corresponding STATUS_IOUT register, and
• Notify the host by pulling the ALERTB pin low.
IOUT_OC_FAULT_RESONSE and IOUT_UC_FAULT_RESPONSE Data Contents
BIT(S) SYMBOL OPERATION
b[7:6] Iout_oc_fault_response_action,
Iout_uc_fault_response_action
Response action:
00b and 01b: The unit continues operation without interruption. Note that the current will not be limited to the
value of Iout_oc_fault_limit or Iout_uc_fault_limit.
10b: The unit continues operating for the delay time specified by bits [2:0]. If the fault is still present at the
end of the delay time, the unit shuts down immediately or sequences off after TOFF_DELAY (See Mfr_config_
track_enn). After shutting down, the device responds according to the retry settings in bits [5:3]. Note that
the current will not be limited to the value of Iout_oc_fault_limit or Iout_uc_fault_limit.
11b: The unit shuts down immediately or sequences off after TOFF_DELAY (See Mfr_config_track_enn). After
shutting down, the device responds according to the retry settings in bits [5:3].
b[5:3] Iout_oc_fault_response_retry,
Iout_uc_fault_response_retry
Response retry behavior:
000b: A zero value for the retry setting means that the unit does not attempt to restart. The output remains
disabled until the fault is cleared.
001-111b: The PMBus device attempts to restart the number of times specified by the global Mfr_retry_
count[2:0] until it is commanded off (by the control pin or operation command or both), bias power is
removed, or another fault condition causes the unit to shut down.
Changing the value might not take effect until the next off-then-on sequence on that channel.
b[2:0] Iout_oc_fault_response_delay,
Iout_uc_fault_response_delay
This sample count determines the amount of time a unit is to ignore a fault after it is first detected. Use this
delay to deglitch fast faults.
000b: There is no additional deglitch delay applied to fault detection.
001b-111b: The fault is deglitched for the interval selected by b[2:0] as follows.
b[2:0] Deglitch interval
001b 100µs
010b 1ms
011b 5ms
100b 10ms
101b 20ms
110b 50ms
111b 100ms
pMbus coMManD DescripTion