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.