L6751C datasheet(27/57 Pages) STMICROELECTRONICS

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L6751C

Device description and operation

The L6751C device is a programmable 4/5/6-phase PWM controller that provides complete

control logic and protection to realize a high performance step-down DC-DC voltage

regulator optimized for advanced microprocessor and memory power supply. The device

features 2nd generation LTB Technology: through a load transient detector, it is able to turn

on simultaneously all the phases. This allows the output voltage deviation to be minimized

and, in turn, the system cost to be minimized by providing the fastest response to a load

transition.

The L6751C implements current reading across the inductor in fully differential mode.

A sense resistor in series to the inductor can also be considered to improve reading

precision. The current information read corrects the PWM output in order to equalize the

average current carried by each phase.

The controller supports Intel and AMD SVI bus and all the required registers. The platform

may configure and program the defaults for the device through dedicated pin-strapping.

A complete set of protections is available: overvoltage, undervoltage, overcurrent (per-

phase and total), and feedback disconnection guarantees the load to be safe in all

circumstances.

Special power management features like DPM, VFDE(a) and GDC modify phase number,

gate driving voltage and switching frequency to optimize efficiency over the load range.

The L6751C is available in WPLGA72 6 x 6 mm package.

a. VFDE feature can be enabled using dedicated PMBus command. See Section 12 on page 48 for details.

Figure 5. Device initialization

SVI Packet

VCC5

VDRV

VIN

UVLO

2mSec POR

UVLO

µSec

SVI BUS

PMBus

V_SinglePhase

ENVTT

SVRRDY

V_MultiPhase

VRRDY

µSec

SVI Packet

Command Rejected

Command ACK but not executed

AM14813v1

L6751C Datasheet(PDF) 27 Page - STMicroelectronics

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