© Semtech Corporation

POWER MANAGEMENT



SC531

Triple Low-side FET Driver with

Digitally Controlled Current Limit

Features

Dual 2A Source, 4A Sink FET Drivers

Second Channel Enable

Independent Drive Supplies

Auxiliary 2A Source, 4A Sink FET Driver

Precision Reference Output

Current Limit Reference Output (Analog) Integrated

Current Sense Blanking (Digital Input)

Digitally Controlled High Precision Current Limit

Current Limit Flag

Current Input ZVS Comparator

SPI Communications — 25 MHz

Thermally Enhanced 4x4 (mm) MLPQ-UT-28 Package

Lead-free, Halogen free, and RoHS/WEEE compliant

Applications

Digitally Controlled Power Supplies

Flyback Converter

Boost Converter

Forward Converter

DC-DC and AC-DC Converters With Active Clamp

PFC Converters With ZVT

Constant Current Converter

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Description

The SC53 combines three low side drivers with a high

speed digitally programmable current limit and a zero

voltage switching (ZVS) comparator. Two drivers are nor-

mally used to operate the FETs for the power stage. They

can operate separately to drive individual power FETs or

can be combined to drive a single device. A third, auxil-

iary, gate drive is controlled by an independent input and

can be used to drive the FET for an active clamp or ZVT

switching. All three drivers have an independent supply

which allows each drive voltage to be optimized for high

efficiency.

In addition, the SC53 has an SPI interface, 8-bit DAC, and

current limit comparator to provide a high-speed digitally

programmable current limit. This circuitry can be used for

cycle by cycle current limiting or current waveform

shaping. A digital output current limit flag is available for

monitoring by the host controller.

The SC53 also has a current-input ZVS comparator that

can be used to sense changes in high voltage nodes, such

as the power FET drain and inductor node (LX) versus the

power stage supply, (HV

circuit).

Typical Application Circuit

Rev 2.0

SC531

GND

VCC

CSENSE

DAC

VREFH

VREF

CSB

BLANKB

CLK

VREFL

OE2B

IN3

A0

ZVS

IN

DIN

47nF

8-bit

DAC

SPI

Interface

1µF

3.3V

D2

T1

15pF

180pF*

1kW

200W*

D1

2.49W

Q3

Q2

Q1

CLF

PVDD3

PGND3

OUT3

1µF

9V

PVDD2

PGND2

OUT2

1µF

9V

PVDD1

PGND1

OUT1

1µF

9V

ZVSP

ZVSN

1MW

1MW

C3

*optional