High Efficiency Integrated Driver for

4-Strings of 150mA LEDs

SC445

POWER MANAGEMENT

Revision 2.1

1

Features

Wide input voltage range from 4.5V to 27V

Sustain fast Vin fluctuation up to 5v/µs

42V maximum output voltage

Drives up to 40 WLEDs in 4 strings

Programmable LED current for up to 150mA per

string

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

Up to 90% efficiency

Wide 0.2% to 100% PWM dimming range

Enable analog dimming

Integrated 3.0A power switch

700KHz switching frequency for small size

Adjustable OVP for cost-effective output cap selection

Open/short LED protection

Short LED protection enable/disable

Thermal protection with auto-recovery

Thermally enhanced TSSOP-20 EDP package

Lead-free, Halogen-Free and WeEE/RoHS Compliant



































Description

The SC445 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 and can sustain fast

Vin transient up to 5V/µs. It can drive up to forty WLEDs in

4 strings with current up to 150mA per string. The string-

to-string current matching is 2% typical, 3% maximum.

The overall efficiency is greater than 90% due to the low

current sense voltage and a low-impedance internal pow-

er 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 efficiency. When

there are fewer than 10 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 SC445 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, unaffected

LED strings. This feature allows LCD panels to remain view-

able even under LED failure, wire disconnect, or short-cir-

cuit conditions. The internal thermal shutdown protects

the IC from overheating at abnormal conditions.

The SC445 is available in a thermally-enhanced TSSOP-20

EDP package.

Typical Application Circuit

1

4

VOUT

SS

PGND

IOSET

IO1-4

COMP

OVPIN

AGND

VIN

SW

PWM

EN

SW

FFLAG

PGND

IOGND

SC445

4 Strings

1

12

Vin (4.5V -27V)

2

EDP

PGND

IOSET

IO1- 4

COMP

SS

AGND

VOUT

OVPIN

SCP_EN

Applications

Medium-sized LCD panel

Notebook Display

Automotive Car Navigation Display

Sub-Notebook and Tablet Computer Displays

Portable Media Players









