LTC2977 datasheet(106/138 Pages) AD

106 / 138 page

LTM4664A

106

Rev. 0

For more information www.analog.com

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

TheUT_FAULT_LIMITcommandsetsthevalueofthepowerstagesensetemperaturemeasuredbytheADC,indegreesCelsius,

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

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

L11

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

L11

0xC300

TON_MAX_FAULT_LIMIT

0x62

Maximum time from the start of

TON_RISE for VOUT to cross the

VOUT_UV_FAULT_LIMIT.

R/W Word

L11

0xCA80

VOUT_TRANSITION_RATE

0x27

Rate the output changes when VOUT

commanded to a new value.

R/W Word

L11

V/ms

0.001

0x8042

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 LTM4664A 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.

PMBus COMMAND DETAILS

LTC2977 Datasheet(PDF) 106 Page - Analog Devices

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