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L6712A L6712

REFERENCE SCHEMATIC

DEVICE DESCRIPTION

The device is an integrated circuit realized in BCD technology. It provides complete control logic and pro-

tections for a high performance dual-phase step-down converter optimized for high current DC/DC appli-

cations. It is designed to drive N-Channel Mosfets in a two-phase synchronous-rectified buck topology. A

180 deg phase shift is provided between the two phases allowing reduction in the input capacitor current

ripple, reducing also the size and the losses. The output voltage of the converter can be precisely regu-

lated, programming the VID pins, from 0.900 to 3.300V with a maximum tolerance of ±0.9% over temper-

ature and line voltage variations. The programmable Remote Sense Amplifier avoids the use of external

resistor divider allowing recovering drops across distribution lines and also adjusting output voltage to dif-

ferent values from the available reference. The device provides an average current-mode control with fast

transient response. It includes a 150kHz free-running oscillator externally adjustable through a resistor.

The error amplifier features a 15V/

µs slew rate that permits high converter bandwidth for fast transient per-

in series to the LS mos in fully differential mode. The current information corrects the PWM outputs in order

to equalize the average current carried by each phase. Current sharing between the two phases is then

limited at ±10% over static and dynamic conditions unless considering the sensing element spread. Droop

effect can be programmed in order to minimize output filter and load transient response: the function can

be disabled and the current information available on the pin can be used for other purposes. The device

protects against Over-Current, with an OC threshold for each phase, entering in constant current mode.

Since the current is read across the low side mosfets, the device keeps constant the bottom of the induc-

tors current triangular waveform. When an Under Voltage is detected the device resets with all mosfets

OFF and suddenly re-starts. The device also performs a crowbar Over-Voltage protection that immediate-

ly latches the operations turning ON the lower driver and driving high the FAULT pin.

PGOOD

PGND

PGNDS2

ISEN2

LGATE2

VSEN

PHASE2

UGATE2

BOOT2

VCC

SGND

OSC / INH

VID0

VID1

VID2

REF_IN/OUT

PGNDS1

ISEN1

LGATE1

PHASE1

UGATE1

BOOT1

VCCDR

FBR

FBG

Rg

Rg

LS2

HS2

L2

C

IN

C

OUT

S1

S0

S2

Rg

LS1

L1

HS1

Vin

GNDin

PGOOD

L6712

L6712A

LOAD

Rg

FB

COMP

DROOP

R

FB

R

F

C

F