LTM4677 datasheet(87/110 Pages) AD

87 / 110 page

LTC3888-1

Rev. 0

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These commands can be used to establish required sequencing and tracking for any number of system power supply rails.

MFR_RESTART_DELAY

The MFR_RESTART_DELAY command specifies the minimum rail off time (RUN low) in milliseconds. The LTC3888-1

will actively hold its RUN pin low for this length of time if a falling RUN edge is detected. After this delay, a standard

start-up sequence can be initiated. A minimum of TOFF_DELAY + TOFF_FALL + 136ms is recommended for this com-

mand value. Valid value range is 136ms to 65.52 seconds. The LTC3888-1 will not produce delays outside of this range

and uses a resolution of 16ms for this command.

This command has two data bytes in Linear_5s_11s format.

TON_DELAY

The TON_DELAY command sets the delay, in milliseconds, between a PWM start condition and the beginning of the

output voltage rise. Values from 0ms to 83 seconds are considered valid, and the LTC3888-1 will not produce delays

outside of this range.

This command has two data bytes in Linear_5s_11s format.

TON_MAX_FAULT_LIMIT

The TON_MAX_FAULT_LIMIT command sets the maximum time, in milliseconds, the unit is allowed from the begin-

ning of the soft-start ramp to power up the output without passing VOUT_UV_FAULT_LIMIT. A value of 0ms means

there is no limit and the unit can attempt to bring up the output voltage indefinitely. The maximum allowed TON_MAX

is 8 seconds. To avoid generation of spurious faults, the value of this command should be set to meet the following

guideline.

TON_MAX_FAULT_LIMIT ≥ 1.25xVOUT_COMMAND/VOUT_TRANSITION_RATE

This command has two data bytes in Linear_5s_11s format.

PMBus COMMAND DETAILS (Output Timing, Delays, and Ramping)

OUTPUT TIMING, DELAYS, AND RAMPING

COMMAND NAME

CMD

CODE DESCRIPTION

TYPE

PAGED

DATA

FORMAT UNITS NVM

DEFAULT

VALUE

MFR_RESTART_DELAY

0xDC Minimum time RUN pin is held low by the

LTC3888-1.

R/W Word

L11

500ms

0xFBE8

TON_DELAY

0x60 Delay from RUN pin or OPERATION on

command to beginning of soft-start ramp.

R/W Word

L11

0.0ms

0x8000

TON_MAX_FAULT_LIMIT

0x62 Maximum time for VFB (default) or VOUT to

rise above VOUT_UV_FAULT_LIMIT after

TON_DELAY.

R/W Word

L11

10.0ms

0xD280

VOUT_TRANSITION_RATE

0x27 Slew rate for VFB (default) or VOUT soft-on/

off and margining, including changes to

VOUT_COMMAND.

R/W Word

L11

ms–1

0.01

0x82BF

TOFF_DELAY

0x64 Delay from RUN pin or OPERATION off

command to beginning of soft-off ramp.

R/W Word

L11

0.0ms

0x8000

TOFF_MAX_WARN_LIMIT

0x66 Maximum time for VOUT to reach

0.125xVOUT_COMMAND after being

commanded to 0.0V.

R/W Word

L11

0.0ms

0x8000

Related commands: MFR_RETRY_DELAY, STATUS_VOUT, SMBALERT_MASK, TON_MAX_FAULT_RESPONSE

LTM4677 Datasheet(PDF) 87 Page - Analog Devices

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