1FEATURES

2• Internal Power-on Reset

• Active Low Reset

• Internal Precision Oscillator

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

Hz–0.625 Hz)

APPLICATIONS

• Customized Flashing LED Lights for Cellular

Phones

• Portable Applications

• Digital Cameras

• Indicator Lamps

• General Purpose I/O Expander

• Toys

KEY SPECIFICATIONS

• 8 LED Driver (Multiple Programmable

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

Specified Rate)

• 8 Open Drain Outputs Capable of Driving up to

25 mA per LED

DESCRIPTION

LP3944 is an integrated device capable of

independently driving 8 LEDs. This device also

contains an internal precision oscillator that provides

all the necessary timing required for driving each

LED. Two prescaler registers along with two PWM

registers provide a versatile duty cycle control. The

LP3944 contains the ability to dim LEDs in

SMBUS/I2C applications where it is required to cut down on bus traffic.

Traditionally, to dim LEDs using a serial shift register such as 74LS594/5 would require a large amount of

traffic to be on the serial bus. LP3944 instead

requires only the setup of the frequency and duty

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

command from the host is required to turn each

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

programmed frequency and duty cycle. Maximum

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

package. Any ports not used for controlling the LEDs

can be used for general purpose input/output

expansion.