Datasheet

LTC3880/LTC3880-1
78
3880fc
For more information www.linear.com/LTC3880
PMBus COMMAND DETAILS
TIMING
Timing—On Sequence/Ramp
COMMAND NAME CMD CODE DESCRIPTION TYPE PAGED
DATA
FORMAT UNITS NVM
DEFAULT
VALUE
TON_DELAY 0x60 Time from RUN and/or Operation on to output
rail turn-on.
R/W Word Y L11 ms Y 0.0
0x8000
TON_RISE 0x61 Time from when the output starts to rise
until the output voltage reaches the VOUT
commanded value.
R/W Word Y L11 ms Y 8.0
0xD200
TON_MAX_FAULT_LIMIT 0x62 Maximum time from V
OUT_EN
on for VOUT to
cross the VOUT_UV_FAULT_LIMIT.
R/W Word Y L11 ms Y 10.0
0xD280
VOUT_TRANSITION_RATE 0x27 Rate the output changes when VOUT
commanded to a new value.
R/W Word Y L11 V/ms Y 0.25
0xAA00
TON_DELAY
The TON_DELAY command sets the time, in milliseconds, from when a start condition is received until the output
voltage starts to rise. Values from 0ms to 83 seconds are valid.
This command has two data bytes and is formatted in Linear_5s_11s format.
TON_RISE
The TON_RISE command sets the time, in milliseconds, from the time the output starts to rise to the time the output
enters the regulation band. Values from 0 to 1.3 seconds are valid. The part will be in discontinuous mode during
TON_RISE events. If TON_RISE is less than 0.25ms, the LTC3880 digital slope will be bypassed. The output voltage
transition will be controlled by the analog performance of the PWM switcher. The maximum allowed slope is 4V/ms.
This command has two data bytes and is formatted in Linear_5s_11s format.
TON_MAX_FAULT_LIMIT
The TON_MAX_FAULT_LIMIT command sets the value, in milliseconds, on how long the unit can attempt to power up
the output without reaching the output undervoltage fault limit.
A data value of 0ms means that there is no limit and that the unit can attempt to bring up the output voltage indefinitely.
The maximum limit is 83 seconds.
This command has two data bytes and is formatted in Linear_5s_11s format.
VOUT_TRANSITION_RATE
When a PMBus device receives either a VOUT_COMMAND or OPERATION (Margin High, Margin Low) that causes the
output voltage to change this command set the rate in V/ms at which the output voltage changes. This commanded
rate of change does not apply when the unit is commanded on or off.
Values of greater than 0.1V/ms are recommended.
This command has two data bytes and is formatted in Linear_5s_11s format.