LX1994

Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 1

High Efficiency LED Driver

Copyright

© 2003

Rev. 1.0a, 2004-08-10

TM

®

DESCRIPTION

Microsemi’s LX1994 is a compact,

high

efficiency,

step-up

boost

controller which is designed to drive a

string of white or colored LED’s in a

backlight or front light system. The

LX1994 design is based on a dual

mode PFM architecture and provides

maximum typical efficiency greater

than 92%.

The LX1994 has many unique

design features and advantages over

competitor solutions. The features

included:

low quiescent current

(100µA typical), low shut down

current (<1µA), dedicate ambient light

sensor

interface

(LX1970),

dual

dimming modes, low voltage and low

offset current sense, and integrated

OVP protection.

The

converter

achieves

high

efficiency, low cost, and flexible

design by selection of an external N-

Channel MOSFET, current sense

resistors,

and

integrated

OVP

protection.

The use of external N-channel

MOSFET allows design to optimize

system efficiency.

The OVP protection comparator

eliminates the need of an external Zener

diode clamp. The OVP function can be

scaled

for

any

output

voltage.

Maximum output current is achievable

by selection of the current sense

resistor.

These features make the

controller ideal for PDA or digital

camera applications

To enhance system battery life, the

LX1994 provides 2 dimming options

and a dedicated ambient light sensor

(LX1970) interface.

The LX1994 supports a wide range

of system battery voltage inputs which

ranges from 2.0 to 5.5V. The LX1994

is guaranteed to start up at 2.0V input.

The LX1994 is available in miniature

10-pin MLP or MSOP packages.

IMPORTANT:

KEY FEATUR ES

Efficiency > 92%

Dual PFM Architecture To

Extend Battery Life

Up Warranty @ 2.0V

Logic Control Shutdown

100µA Typical Quiescent

Current

OVP For Open String Output

Voltage

Low Voltage And Offset

Current Sense

Light Sensor (LX1970)

interface

Dual Dimming Options (PWM

or DC Voltage)

No External Zener Clamp

Diode

10-Pin MLP or MSOP

APPLI C ATION S

Pagers

PDA

Cell Phone

Portable Display

Digital Cameras

PRODUCT H I GHLIGHT

DRV

SRC

OVP

S/P

VIN

BRT

V

GND

LX1994

FB

33µH

FDV303

UPS5819

LS

SNK

SRC

VSS

VDD

LX1970

3V

CMP

Auto Adjust for

Ambient Light

PACKAGE ORDER INFO

°C)

LD

Plastic MLP

10-Pin

DU

Plastic MSOP

10-Pin

-40 to 85

LX1994CLD

LX1994CDU

Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e.

LX1994CDU-TR)