L6751B datasheet(52/58 Pages) STMICROELECTRONICS

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PMBus support (preliminary)

L6751B

52/58

Doc ID 024028 Rev 1

Note:

Applies to multi-phase only.

Applies to single-phase only.

12.1

Enabling the device through PMBus

The default condition for the L6751B is to power up through the EN pin ignoring PMBus

commands. By properly setting the ON_OFF_CONFIG command, it is also possible to let

the device ignore the EN pin acting only as a consequence of the OPERATION command

issued.

12.2

Controlling Vout through PMBus

Vout can be set independently from SetVID commands issued through the SVI interface by

using PMBus. Two main modes can be identified as:

–

Offset above SVI commanded voltage.

By enabling the MARGIN mode through the OPERATION command and by

commanding the MARGIN_HIGH and MARGIN_LOW registers, it is possible to

dynamically control an offset above the output voltage commanded through the

SVI bus.

–

Fixed Vout regardless of SVI.

It is necessary to enter DEBUG_MODE. In this condition, commands from SVI are

acknowledged but not executed and VOUT_COMMAND controls the voltage

regulated on the output.

The L6751B can enter and exit DEBUG_MODE anytime. Upon any transition, Vout

remains unchanged and only the next-coming command affects the output voltage

positioning (i.e. when exiting DEBUG_MODE, returning to SVI domain, output

voltage remains unchanged until the next SetVID command).

STATUS_INPUT

R Byte

Status information on the input warning and fault

STATUS_MFR_SPECI

FIC

R Byte

Manufacturer specific status

Table 16.

Supported commands

Command

Per

Rail

Code

[Hex]

Mode

Comments

L6751B Datasheet(PDF) 52 Page - STMicroelectronics

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