LTC2977 datasheet(110/138 Pages) AD

110 / 138 page

LTM4664A

110

Rev. 0

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0xB8–The device shuts down (disables the output) and device attempts to retry continuously, without limitation, until

it is commanded OFF (by the RUN pin or OPERATION command or both), bias power is removed, or another fault

condition causes the unit to shut down.

0x4n The device shuts down and the unit does not attempt to retry. The output remains disabled until the part is com-

manded OFF then ON or the RUN pin is asserted low then high or RESET through the command or removal of VIN.

The OV fault must remain active for a period of n • 10µs, where n is a value from 0 to 7.

0x78+n The device shuts down and the unit attempts to retry continuously until either the fault condition is cleared

or the part is commanded OFF then ON or the RUN pin is asserted low then high or RESET through the command or

removal of VIN. The OV fault must remain active for a period of n • 10µs, where n is a value from 0 to 7.

Any other value will result in a CML fault and the write will be ignored.

This command has one data byte.

Table 14. VOUT_OV_FAULT_RESPONSE Data Byte Contents

BITS

DESCRIPTION

VALUE MEANING

7:6

Response

For all values of bits [7:6], the LTM4664A:

• Sets the corresponding fault bit in the status commands and

• Notifies the host by asserting ALERT pin, unless masked.

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

following events occurs:

• The device receives a CLEAR_FAULTS command.

• The output is commanded through the RUN pin, the OPERATION

command, or the combined action of the RUN pin and

OPERATION command, to turn off and then to turn back on, or

• Bias power is removed and reapplied to the LTM4664A.

Part performs OV pull down only or OV_PULLDOWN

(i.e., turns off the top MOSFET and turns on lower MOSFET

while VOUT is > VOUT_OV_FAULT).

The PMBus device continues operation for the delay time

specified by bits [2:0] and the delay time unit specified for that

particular fault. If the fault condition is still present at the end of

the delay time, the unit responds as programmed in the Retry

Setting (bits [5:3]).

The device shuts down 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

The unit does not attempt to restart. The output remains

disabled until the fault is cleared until the device is commanded

OFF bias power is removed.

111

The PMBus device attempts to restart continuously, without

limitation, until it is commanded OFF (by the RUN pin or

OPERATION command or both), bias power is removed, or

another fault condition causes the unit to shut down without

retry. Note: The retry interval is set by the MFR_RETRY_DELAY

command.

2:0

Delay Time

000-111 The delay time in 10µs increments. This delay time determines

how long the controller continues operating after a fault is

detected. Only valid for deglitched off state.

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 data byte is in the format given in Table 8.

The device also:

• Sets the NONE_OF_THE_ABOVE bit in the STATUS_BYTE

• 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 pin, unless masked

PMBus COMMAND DETAILS

LTC2977 Datasheet(PDF) 110 Page - Analog Devices

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