Ot_fault_response, Ot_warn_limit – Maxim Integrated MAX15303 PMBus Command Set User Manual
Page 23
MAX15303 PMBus Command Set User’s Guide
Page 23 of 52
OT_FAULT_RESPONSE
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x50
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 15.18 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 OT_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.
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 overcurrent faults is 000
bin
.)
OT_WARN_LIMIT
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x51
Format:
Linear
Data Bytes:
2
Units:
°C
Transfer:
Read/Write Word
Factory Value:
0xEAF8 (95°C)
Description/Notes: See Section 15.19 of the PMBus Specification Part II.
The MAX15303 has an internal temperature signal and can also measure temperature at an external
location, using a diode junction.
The OT_WARN_LIMIT applies to the external temperature signal, if a valid sensor is detected during
initialization. If no external sensor is detected, the OT_WARN_LIMIT applies to the internal
d
An overtemperature fault (i.e., relevant temperature signal above
) is not considered to have abated until
the temperature has fallen below the