LTM2987 datasheet(21/114 Pages) AD

21 / 114 page

LTC2971

Rev. 0

For more information www.analog.com

OPERATION

LTC2971 OPERATION OVERVIEW

The LTC2971 is a PMBus programmable power supply

controller, monitor, sequencer and voltage supervisor that

can perform the following operations:

• Accept PMBus compatible programming commands.

• ProvideDC/DCconverterinputvoltage,outputvoltage,

output current, output temperature, and LTC2971

internal temperature readback through the PMBus

interface.

• Connect directly to a DC/DC converter's IMON pin or

the DCR sense network for output current telemetry

readback.

• Control the output of DC/DC converters that set the

output voltage with a trim pin or DC/DC converters

that set the output voltage using an external resistor

feedback network.

• Sequence the startup of DC/DC converters via PMBus

programming and the CONTROL input pins. The

LTC2971 supports time-based sequencing and track-

ingsequencing.CascadesequenceONwithtimebased

sequence OFF is also supported.

• Trim the DC/DC converter output voltage (typically in

0.02% steps), in closed-loop servo operating mode,

autonomously or through PMBus programming.

• Margin the DC/DC converter output voltage to PMBus

programmed limits.

• Trim or margin the DC/DC converter output voltage

with direct access to the margin DAC.

• Supervise the DC/DC converter input voltage, output

voltage and the inductor temperatures for overvalue/un-

dervalueconditionswithrespecttoPMBusprogrammed

limits and generate appropriate faults and warnings.

• Accurately handle inductor self-heating transients

using a proprietary algorithm. These self-heating

effects are combined with external temperature sen-

sor readings to improve accuracy of ADC current

measurements.

• Respond to a fault condition by continuing operation

indefinitely,latching-offafteraprogrammabledeglitch

period, latching-off immediately or sequencing off

after TOFF_DELAY. Use retry mode to automatically

recover from a latched-off condition. With retry en-

abled, MFR_RETRY_COUNT programs the number of

retries (0 to 6 or infinite) for both pages.

• Optionally stop trimming the DC/DC converter output

voltage after it reaches the initial margin or nominal

target. Optionally allow trimming restart if target drifts

outside of VOUT warning limits.

• Store command register contents to EEPROM with

CRC and ECC through PMBus programming.

• Restore EEPROM contents through PMBus program-

ming or when VDD33 is applied on power-up.

• GenerateinterruptrequestsbyassertingtheALERTBpin

in response to supported PMBus faults and warnings.

• Coordinate system wide fault responses for all DC/DC

converters connected to the LTC2971 FAULTB0 and

FAULTB1 pins.

• Propagate per-channel POWER GOOD status via the

PG0 and PG1 pins, or configure these pins as general-

purpose IOs.

• Synchronize sequencing delays or shutdown for

multiple devices using the SHARE_CLK pin.

• Software and hardware write protect the command

registers.

• Disable the supervised DC/DC converters in response

to output OV and UV faults.

• Log telemetry and status data to EEPROM in response

to a faulted-off condition.

• Supervise an external microcontroller’s activity for

a stalled condition with a programmable watchdog

timer and reset it if necessary.

LTM2987 Datasheet(PDF) 21 Page - Analog Devices

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