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LTC3882-1

Rev A

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VOUT_OV_FAULT_RESPONSE

The VOUT_OV_FAULT_RESPONSE command instructs the device on what action to take in response to an output

overvoltage fault. The format for this command is given in Table 12. The device also:

• Sets the VOUT_OV Bit in the STATUS_BYTE

• Sets the VOUT Bit in the STATUS_WORD

• Sets the VOUT Overvoltage Fault Bit in the STATUS_VOUT Command

• Notifies the Host by Asserting ALERT, Unless Masked

This command has one data byte.

VOUT_UV_FAULT_RESPONSE

The VOUT_UV_FAULT_RESPONSE command instructs the device on what action to take in response to an output

undervoltage fault. The format for this command is given in Table 12. The device also:

• Sets the VOUT Bit in the STATUS_WORD

• Sets the VOUT Undervoltage Fault Bit in the STATUS_VOUT Command,

• Notifies the Host by Asserting ALERT, Unless Masked

This command has one data byte.

Table 12. Data Byte Contents for VOUT_OV_FAULT_RESPONSE and VOUT_UV_FAULT_RESPONSE

BITS

DESCRIPTION

VALUE

MEANING

[7:6]

For all values of bits [7:6], the LTC3882-1:

• Sets the corresponding fault bits in the status commands.

• Notifies the host by asserting ALERT, unless masked.

The fault, once set, is cleared only when one or more of the

following events occurs:

• The device receives a CLEAR_FAULTS command.

• The corresponding STATUS_VOUT bit is written to a one.

• The output is commanded off, then on, by the RUN pin or

OPERATION command.

• The device receives a RESTORE_USER_ALL command.

• The device receives an MFR_RESET command.

• IC supply power is cycled.

The LTC3882-1 continues to operate indefinitely with the

normal hardware response described in the Operation

section.

The LTC3882-1 continues operating with the normal

hardware response for the delay time specified by bits [2:0].

If the fault is continuously present for the entire delay, the

unit then disables the output and does attempt to restart.

The LTC3882-1 immediately disables the output and

responds according to the retry setting in bits [5:3].

Not supported. Writing this value will generate a CML fault.

[5:3]

Retry setting.

000-110

The LTC3882-1 does not attempt to restart. The output

remains disabled until the fault is cleared, the device is

commanded off and then on, or bias power (LTC3882-1

power supply input) is cycled.

111

The LTC3882-1 attempts to restart continuously without

limitation with an interval set by MFR_RETRY_DELAY.

This response persists until the unit is commanded off, or

bias power is removed, or another fault response forces

shutdown without retry.

[2:0]

Delay time.

xxx

Response delay time in 10µs increments. This delay

time determines how long the fault may have to persist

before the controller is disabled, depending on bits [7:6].

Hardware-level response, if any, will occur during this delay.

These bits always return zero if bits [7:6] are not set to 0x2.

PMBus COMMAND DETAILS (Fault Response and Communication)

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