PMBus 6-Channel Power-Supply Manager

25

ON_OFF_CONFIG (02h)

The ON_OFF_CONFIG command configures the combination of CONTROL input and PMBus OPERATION commands

needed to turn the power supply on and off. This indicates how the power supply is commanded when power is

applied. Table 10 describes the ON_OFF_CONFIG message content. The host should not modify ON_OFF_CONFIG

while the power supplies are active.

CLEAR_FAULTS (03h)

The CLEAR_FAULTS command is used to clear any fault or warning bits in the status registers that have been set.

This command clears all bits simultaneously. The CLEAR_FAULTS command does not cause a power supply that has

latched off for a fault condition to restart. The status of PSEN under fault conditions is not affected by this command

and changes only if commanded through the OPERATION command or CONTROL pin. If a fault is still present after the

CLEAR_FAULTS command is executed, the fault status bit is set again and the host is also notified by asserting ALERT

(if enabled in MFR_MODE). This command is write-only. There is no data byte for this command.

WRITE_PROTECT (10h)

The WRITE_PROTECT command is used to provide protection against accidental changes to the device operating

memory. All supported commands can have their parameters read, regardless of the WRITE_PROTECT settings. The

WRITE_PROTECT message content is described in Table 11.

Table 10. ON_OFF_CONFIG (02h) Command Byte

Table 11. WRITE_PROTECT Command Byte

Note: No fault or error is generated if the host attempts to write to a protected area.

BIT

PURPOSE

BIT VALUE

MEANING

7:5

Reserved

N/A

Always returns 000.

4

Turn on supplies when bias is

present or use the CONTROL pin

and/or OPERATION command

0

Turn on the supplies (with sequencing, if so configured) as soon

as bias is supplied to the device regardless of the CONTROL pin.

1

Operate the supplies as instructed by the CONTROL pin and/or

the OPERATION command.

3

OPERATION Command Enable

0

Ignore the on/off portion of the OPERATION command.

1

OPERATION command enabled and required for action.

2

CONTROL Pin Enable

0

Ignore the CONTROL pin.

1

CONTROL pin enabled and required for action.

1

CONTROL Pin Polarity

0

Active low (drive low to turn on the power supplies).

1

Active high (drive high to turn on the power supplies).

0

CONTROL Pin Turn-Off Action

0

Use the programmed turn-off delay (soft off).

1

Turn off the power supplies immediately.

COMMAND BYTE

MEANING

80h

Disable all writes except the WRITE_PROTECT command.

40h

Disable all writes except the WRITE_PROTECT, OPERATION, and PAGE commands.

20h

Disable all writes except the WRITE_PROTECT, OPERATION, PAGE, and ON_OFF_CONFIG commands.

00h

Enable writes for all commands (default).