Instruction Manual
MAX15303 PMBus Command Set User’s Guide
Page 21 of 52
VOUT_UV_FAULT_RESPONSE
The VOUT_UV_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. (Default setting)
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.
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.
Bits [2:0] determine the fault-tolerance or retry-delay timing. Each binary value in bits [2:0]
corresponds to a multiple of 100ms, up to a possible maximum of 111
bin
= 700ms. A value of 000
bin
will cause the MAX15303 to use the minimum possible timing value, typically about 30-40ms. (The
default timing for undervoltage faults is 000
bin
.)
IOUT_OC_FAULT_LIMIT
Reference: Standard Command Lockable: Yes
Command Code: 0x46 Format: Linear
Data Bytes: 2 Units: A
Transfer: Read/Write Word Factory Value: 0xD200 (8A)
Description/Notes: See Section 15.8 of the PMBus Specification Part II.
The MAX15303 hardware has 8-bit resolution for the overcurrent fault limit within a 9A full-scale load
current range.
The desired value of IOUT_OC_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.
IOUT_OC_FAULT_RESPONSE
Reference: Standard Command Lockable: Yes
Command Code: 0x47 Format: Bit field
Data Bytes: 1 Units: N/A
Transfer: Read/Write Byte Factory Value: 0xBF (Shut down, retry every 700ms)
Description/Notes: See Sections 10.5.1 and 15.9 of the PMBus Specification Part II.
For overcurrent faults, the MAX15303 implements the fault responses of PMBus Specification section
10.5.1, rather than the responses of section 10.5.2.
Note that…