LM2794/95

C1+

GND

BRGT

D1

D2

C1-

SD

1PF

C2-

C1

1PF

C2

1PF

1PF

D3

D4

C2+

LED2

LED1

LED3

LED4

LM2794, LM2795

www.ti.com

SNVS168K – MAY 2004 – REVISED MAY 2004

LM2794 /LM2795 Current Regulated Switched Capacitor LED Supply with Analog and

PWM Brightness Control

Check for Samples: LM2794, LM2795

1

FEATURES

•

Constant Frequency generates predictable

noise spectrum

2

•

Regulated current sources with ±0.5%

•

Standard Micro SMD-14 package: 2.08mm X

matching between any two outputs

2.403mm X 0.845mm High

•

High efficiency 3/2 boost function

•

Thin Micro SMD-14 package: 2.08mm X

•

Drives one, two, three or four white LEDs

2.403mm X 0.600mm High

•

2.7V to 5.5V Input Voltage

•

Up to 80mA output current

APPLICATIONS

•

Analog brightness control

•

White LED Display Backlights

•

Active-low or high shutdown input ('94/95)

•

White LED Keypad Backlights

•

Very small solution size and no inductor

•

1-Cell Li-Ion battery-operated equipment

•

2.3µA (typ.) shutdown current

including PDAs, hand-held PCs, cellular

•

325kHz switching frequency (min.)

phones

DESCRIPTION

The LM2794/95 is a fractional CMOS charge-pump that provides four regulated current sources. It accepts an

input voltage range from 2.7V to 5.5V and maintains a constant current determined by an external sense resistor.

The LM2794/5 delivers up to 80mA of load current to accommodate four White LEDs. The switching frequency is

325kHz. (min.) to keep the conducted noise spectrum away from sensitive frequencies within portable RF

devices.

Brightness can be controlled by both linear and PWM techniques. A voltage between 0V and 3.0V may be

applied to the BRGT pin to linearly vary the LED current. Alternatively, a PWM signal can be applied to the SD

pin to vary the perceived brightness of the LED. The SD pin reduces the operating current to 2.3µA (typ.) The

LM2794 is shut down when the SD pin is low, and the LM2795 is shut down when the SD pin is high.

The LM2794/95 is available in a micro SMD-14 CSP package.

Basic 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.