Blue LEDs

+5V

+5V

R

G

B

LED0

LED2

LED1

LED3

LED4

LED5

LED6

LED7

RESET

SCL

SDA

5V

SDA

SCL

PORTx.D

Cell Phone Baseband

Controller/PController

A2

A1

A0

GND

SMBUS

/I

2

C

LP3944

www.ti.com

SNVS264 – MAY 2004

LP3944 RGB/White/Blue 8-LED Fun Light Driver

Check for Samples: LP3944

1

FEATURES

DESCRIPTION

LP3944

is

an

integrated

device

capable

of

2

•

Internal Power-on Reset

independently driving 8 LEDs. This device also

•

Active Low Reset

contains an internal precision oscillator that provides

•

Internal Precision Oscillator

all the necessary timing required for driving each

LED. Two prescaler registers along with two PWM

•

Variable Dim Rates (from 6.25 ms to 1.6s; 160

registers provide a versatile duty cycle control. The

Hz–0.625 Hz)

LP3944

contains

the

ability

to

dim

LEDs

in

APPLICATIONS

down on bus traffic.

•

Customized Flashing LED Lights for Cellular

Traditionally, to dim LEDs using a serial shift register

Phones

such as 74LS594/5 would require a large amount of

•

Portable Applications

traffic to be on the serial bus. LP3944 instead

requires only the setup of the frequency and duty

•

Digital Cameras

cycle for each output pin. From then on, only a single

•

Indicator Lamps

command from the host is required to turn each

•

General Purpose I/O Expander

individual open drain output ON, OFF, or to cycle a

programmed frequency and duty cycle. Maximum

•

Toys

output sink current is 25 mA per pin and 200 mA per

package. Any ports not used for controlling the LEDs

KEY SPECIFICATIONS

can

be

used

for

general

purpose

input/output

•

8 LED Driver (Multiple Programmable

expansion.

States—On, Off, Input, and Dimming at a

Specified Rate)

•

8 Open Drain Outputs Capable of Driving up to

25 mA per LED

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.