1 PF*

3/2× Charge Pump

C1

1 PF

C2

1 PF

1 PF*

EN

ENA

ENB

C1+

C1-

C2+

C2-

D1A

D2A

D3A

D4A

D1B

D2B

D3B

2.7V to 5.5V

GND

LM2796

Capacitors: TDK C1608X5R1A105K,

or equivalent

*If total LED current is above 80 mA, as can occur

when all 7 outputs are ON simultaneously, 2.2 PF

Master Enable and Current Source Enables for

ON/OFF Control and PWM Dimming

LM2796

www.ti.com

SNVS273 – MAY 2004

LM2796 Dual-Display White LED Driver with 3/2x Switched Capacitor Boost

Check for Samples: LM2796

1

FEATURES

DESCRIPTION

The LM2796 is a charge-pump based white-LED

2

•

Drives up to 7 LEDs with up to 20mA Each

driver

that

is

ideal

for

mobile

phone

display

•

LEDs Controlled in 2 Distinct Groups, for

backlighting. It can drive up to 7 LEDs in parallel with

Backlighting 2 Displays (Main LCD and Sub-

up to 20mA through each LED. Regulated internal

LCD)

current

sources

deliver

excellent

current

and

brightness matching in all LEDs. The LED-driver

•

Excellent Current and Brightness Matching

current sources are split into two independently

•

High-Efficiency 3/2x Charge Pump

controlled groups. The primary group (4 LEDs) can

•

Extended Li-Ion Input: 2.7V to 5.5V

be used to backlight the main phone display. The

•

PWM Brightness Control: 100Hz - 1kHz

second group (3 LEDs) can be used to backlight a

secondary display or to provide other lighting features

•

18-bump Thin DSBGA Package: (2.1mm x

(keypad LEDs, for example). Brightness of the two

2.4mm x 0.6mm)

groups can be adjusted independently with pulse-

width modulated (PWM) digital signals.

APPLICATIONS

The LM2796 works off an extended Li-Ion input

•

Mobile Phone Display Lighting

voltage range (2.7V to 5.5V). Voltage boost is

•

Mobile Phone Keypad Lighting

achieved with a high-efficiency 3/2×-gain charge

pump.

•

PDAs

•

General LED Lighting

The LM2796 is available in National’s chip-scale 18-

bump DSBGA package.

Typical Application Circuit

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2004, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.