Timing; Timing-On Sequence/Ramp - Analog Devices Linear LTM 4700 User Manual

LTM4700
PMBus COMMAND DETAILS
In response to the OT_WARN_LIMIT being exceeded, the device:
• Sets the TEMPERATURE bit in the STATUS_BYTE
• Sets the Overtemperature Warning bit in the STATUS_TEMPERATURE command, and
• Notifies the host by asserting ALERT pin, unless masked
This command has two data bytes and is formatted in Linear_5s_11s format.
UT_FAULT_LIMIT
The UT_FAULT_LIMIT command sets the value of the external sense temperature measured by the ADC, in degrees Celsius,
which causes an undertemperature fault. The READ_TEMPERATURE_1 value will be used to determine if this limit has been
exceeded.
Note: If the temp sensors are not installed, the UT_FAULT_LIMIT can be set to –275°C and UT_FAULT_LIMIT response
set to ignore to avoid ALERT being asserted.
This command has two data bytes and is formatted in Linear_5s_11s format.

TIMING

Timing—On Sequence/Ramp
COMMAND NAME CMD CODE DESCRIPTION
TON_DELAY 0x60
TON_RISE 0x61
TON_MAX_FAULT_LIMIT 0x62
VOUT_TRANSITION_RATE 0x27
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 resulting turn-on delay will have a typical delay of
270µs for TON_DELAY = 0 and an uncertainty of ±50µs for all values of TON_DELAY.
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 LTM4700 digital slope will be bypassed and the output voltage
transition will only 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.
92
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 the start of TON_
RISE for VOUT to cross the VOUT_UV_
FAULT_LIMIT.
Rate the output changes when VOUT
commanded to a new value.
For more information
DATA
TYPE PAGED FORMAT
R/W Word Y L11
R/W Word Y L11
R/W Word Y L11
R/W Word Y L11
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DEFAULT
UNITS NVM VALUE
ms Y 0.0
0x8000
ms Y 8.0
0xD200
ms Y 10.0
0xD280
V/ms Y 0.25
0xAA00
Rev. B