Rainbow Electronics MAX34440 - Manual (Page 31)

PMBus 6-Channel Power-Supply Manager
MAX34440
31
POWER_GOOD_OFF (5Fh)
The POWER_GOOD_OFF command sets the value of the output voltage that causes the PG output to deassert after it
has been asserted. Any enabled power supply that falls below the associated POWER_GOOD_OFF threshold causes
the PG output to be deasserted. The POWER_GOOD_OFF level is normally set lower than the POWER_GOOD_ON
level. The 2 data bytes are in DIRECT format.
When the VOUT level of a power supply falls from greater than POWER_GOOD_ON to less than POWER_GOOD_OFF,
the device does the following:
1) Sets the NONE OF THE ABOVE bit in STATUS_BYTE.
2) Sets the NONE OF THE ABOVE, POWER_GOOD#, and STATUS_MFR_SPECIFIC bits in STATUS_WORD.
3) Sets the POWER_GOOD# bit in STATUS_MFR_SPECIFIC.
TON_DELAY (60h)
TON_DELAY sets the time, in milliseconds, from when a START condition is received (a valid OPERATION command
or through the CONTROL pin when enabled) until the PSEN output is asserted. The undervoltage fault and warning are
masked off during TON_DELAY. The 2 data bytes are in DIRECT format.
TON_MAX_FAULT_LIMIT (62h)
The TON_MAX_FAULT_LIMIT sets an upper time limit, in milliseconds, from when the TON_DELAY and the PSEN
output are asserted until the output voltage crosses the VOUT_UV_FAULT_LIMIT threshold. The 2 data bytes are in
DIRECT format. If the value is 0, the power supply is not sequenced by the device and the associated PSEN output
remains deasserted; voltage and current monitoring is disabled. In response to the TON_MAX_FAULT_LIMIT being
exceeded, the device does the following:
1) Sets the NONE OF THE ABOVE bit in STATUS_BYTE.
2) Sets the NONE OF THE ABOVE and VOUT bits in STATUS_WORD.
3) Sets the TON_MAX_FAULT bit in STATUS_VOUT.
4) Responds as specified in the MFR_FAULT_RESPONSE.
5) Notifies the host using ALERT assertion (if enabled in MFR_MODE).
TOFF_DELAY (64h)
The TOFF_DELAY sets the time, in milliseconds, from when a STOP condition is received (a soft-off OPERATION com-
mand or through the CONTROL pin when enabled) until the PSEN output is deasserted. When commanded to turn off
immediately (either through the OPERATION command or the CONTROL pin), the TOFF_DELAY value is ignored. The
2 data bytes are in DIRECT format.
Table 15. TON_MAX_FAULT_LIMIT
Note: TON_MAX_FAULT_LIMIT should be set higher than 5ms.
TON_MAX_FAULT_LIMIT VALUE DEVICE RESPONSE (FOR THE ASSOCIATED PAGE)
8000h to FFFFh Negative values are invalid.
0000h Channel off (PSEN remains deasserted with no monitoring).
0001h to 7FFFh Channel on and sequencing enabled.