High E ciency Integrated Driver for

4-Strings of 150mA LEDs

SC441C

POWER MANAGEMENT

March 04, 2010

1

www.semtech.com

Features

Applications

Description

Wide input voltage range from 4.5V to 27V

42V maximum output voltage

Drives up to 48 WLEDs in 4 strings

Programmable LED current for up to 150mA per

string

+/- 2% string-to-string current matching

Up to 90% eciency

Wide 0.2% to 100% PWM dimming range

Possible analog dimming

Integrated 2.5A power switch

700KHz switching frequency for small size

Adjustable OVP for cost-e ective output cap selection

Open/short LED protection

Thermal protection with auto-recovery

Thermally enhanced TSSOP-20 EDP package

Pb Free, Halogen Free, andWEEE/RoHS Compliant

Medium-sized LCD panel

Notebook Display

Automotive Car Navigation Display

Sub-Notebook and Tablet Computer Displays

Portable Media Players

The SC441C is a high-eciency multiple string WLED driv-

er 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 2.5A internal power switch.

It can drive up to 48 WLEDs in 4 strings with current up

to 150mA per string. The string-to-string current match-

ing is 2% typical, 3% maximum. The overall eciency 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 500: 1.

The 700KHz switching frequency enables the user to op-

timize the external component sizes for eciency. When

there are fewer than 12 LEDs in each string, users can ad-

just the output voltage protection yielding an allowable

reduction in associated costs, size and voltage ratings of

the output capacitor.

The SC441C also features comprehensive open and short-

circuit LED protection functions. It disables the corre-

sponding strings with LED open or LED short conditions

while maintaining normal operation of other, una ected

LED strings. This feature allows LCD panels to remain

viewable even under LED failure, wire disconnect, or

short-circuit conditions. The internal thermal shutdown

protects the IC from overheating at abnormal conditions.

The SC441C is available in a thermally-enhanced TSSOP-20

EDP package.

Typical Application Circuit