Maxim Integrated MAX15303 PMBus Command Set - Manual (Page 24)

MAX15303 PMBus Command Set User’s Guide
Page 24 of 52
OT_WARN_LIMIT
temperature signal instead.
Overtemperature fault hysteresis is achieved in the MAX15303 by using the OT_WARN_LIMIT as the
“fault cleared” threshold for
OT_FAULT_LIMIT . For this reason, it is important to always set
OT_WARN_LIMIT below OT_FAULT_LIMIT.
VIN_OV_FAULT_LIMIT
Reference: Standard Command Lockable: Yes
Command Code: 0x55 Format: Linear
Data Bytes: 2 Units: V
Transfer: Read/Write Word Factory Value: 0xD380 (14V)
Description/Notes: See Section 15.23 of the PMBus Specification Part II.
The MAX15303 hardware has 8-bit resolution for the input overvoltage fault limit, to a maximum
value of ≈14.75V.
The desired value of VIN_OV_FAULT_LIMIT is retained in memory, regardless limitations imposed by
the 8-bit fault limit resolution, but the read-back value is based on actual hardware register settings.
VIN_OV_FAULT_RESPONSE
Reference: Standard Command Lockable: Yes
Command Code: 0x56 Format: Bit field
Data Bytes: 1 Units: N/A
Transfer: Read/Write Byte Factory Value: 0xC0 (Shut down, restart when fault
abates)
Description/Notes: See Sections 10.5.1 and 15.24 of the PMBus Specification Part II.
Note that the MAX15303 does not support finite, non-zero restart-attempt counts. (Continuous
restart attempts are supported.)
The VIN_OV_FAULT_RESPONSE command data comprises three bit-fields:
Bits [7:6] determine the basic fault-response mode. The MAX15303 supports the following modes:
00 Ignore the fault condition.
01 Continue operating and wait for the fault to abate for time specified in bits [2:0]. If the
fault does not abate, shutdown and attempt to restart according to bits [5:3].
10 Stop regulating immediately, delay for the time specified in bits [2:0], then attempt to
restart according to bits [5:3].
11 Stop regulating immediately, and then restart as soon as possible after the fault
condition abates. (Default setting)
Bits [5:3] determine the number of retry attempts. The MAX15303 supports only a subset of the full
PMBus functionality for this portion of the command:
000-110 No attempt is made to restart after a fault shutdown. (Default setting)
111 Attempt to restart continuously until commanded off, or until another fault
condition causes the unit to shut down.