LTC3883 Datasheet, PDF (80/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
PMBus Command Details
Timing
Timing—On Sequence/Ramp
COMMAND NAME
TON_DELAY
TON_RISE
TON_MAX_FAULT_LIMIT
VOUT_TRANSITION_RATE
CMD CODE
0x60
0x61
0x62
0x27
DESCRIPTION
Time from RUN and/or Operation on to output
rail turn-on.
Time from when the output starts to rise
until the output voltage reaches the VOUT
commanded value.
Maximum time from V_{OUT_EN} on for VOUT to
cross the VOUT_UV_FAULT_LIMIT.
Rate the output changes when VOUT
commanded to a new value.
TYPE
R/W Word
R/W Word
R/W Word
R/W Word
DATA
FORMAT
L11
L11
L11
L11
UNITS
ms
ms
ms
V/ms
DEFAULT
NVM
VALUE
Y
0.0
0x8000
Y
8.0
0xD200
Y
10.0
0xD280
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. The TON_DELAY will have a typical delay of 270µs
with an uncertainty of ±50µs.
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 LTC3883 digital slope will be bypassed. The output voltage
transition will be controlled by the analog performance of the PWM switcher. The number of steps in TON_RISE is
equal to TON_RISE (in ms)/0.1ms with an uncertainty of ±0.1ms.
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. The maximum allowed slope is 4V/ms.
3883f
80