POWER MANAGEMENT

January 21, 2009

1

High Efficiency Integrated Boost Driver

for 3-Strings of 30mA LEDs

SC443

www.semtech.com

Typical Application Circuit

Features

Wide input voltage range from 4.5V to 27V

42V maximum operating output voltage

Programmable LED current for up to 30mA per

string

+/- 1% typical string-to-string current matching

Greater than 90% efficiency

Wide 0.4% to 100% PWM dimming range

Integrated 1A power switch

Programmable switching frequency for small size

Low current sense voltage for high efficiency

Adjustable OVP for cost-effective output cap

selection

LED open circuit protection

Thermal protection with auto-recovery

3mm × 3mm ×0.6mm MLP-UT-16 lead-free package

(WEEE and RoHS compliant)

Applications

Small to Medium Size LCD Panel

Notebook Display

White LED Power Supplies

Sub-Notebook and Tablet Computer Displays

Portable Media Players

LCD Monitors

Digital Video Cameras

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Description

The SC443 is a high-efficiency multiple string WLED driver

with an integrated boost converter. It operates over a wide

input range from 4.5V to 27V with a maximum output

voltage of 42V and a 1A internal power switch.

It can drive 3 strings with current up to 30mA per string.

The string-to-string current matching is within, typically,

1% and the overall efficiency is greater than 90% due

to the low current sense voltage and a low-impedance

internal power switch. The wide PWM dimming range

boasts a ratio of 250: 1.

The programmable switching frequency enables the

user to optimize the external component sizes for high

efficiency. When there are fewer LEDs in each string, users

can use a lower output voltage protection level which

yields an allowable reduction in associated costs, size

and voltage ratings of the output capacitor.

The SC443 also features an open circuit LED protection

function. It disables the corresponding strings with LED

open while keeping other strings under normal operation.

This feature allows LCD panels to remain viewable even

under LED failure and wire disconnectons. The internal

thermal shutdown protects the IC from overheating at

abnormal conditions. The SC443 is available in a 3mm

× 3mm × 0.6mm MLP-UT 16 Lead-free package.

SC443

3

Enable

Dimming

VOUT

SS

PGND

FSET

IOSET

IO1 3

OVPIN

IOGND

PWM

AGND

EN

-

COMP

OVPIN

VIN

SW

AGND