1 Features

• Internal power-on reset

• Active low reset

• Internal precision oscillator

• Variable dim rates

(from 6.25ms to 1.6s; 160Hz to 0.625Hz)

• 16 LED drivers (multiple programmable states:

ON, OFF, input, and dimming at a specified rate)

• 16 open-drain outputs capable of driving up to

25mA per LED

2 Applications

• Customized flashing LED lights for cellular phones

• Portable applications

• Digital cameras

• Indicator lamps

• General purpose I/O expander

• Toys

3 Description

The LP3943 is an integrated device capable of

independently driving 16 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 LP3943 contains the ability to dim LEDs in

SMBUS/I2C applications where it is required, to cut

down on bus traffic.

Traditionally, dimming LEDs using a serial shift

register such as 74LS594/5 requires a large amount

of traffic on the serial bus. The LP3943 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 to an ON or OFF

state, or to cycle a programmed frequency and duty

cycle. Maximum output sink current is 25mA per pin

and 200mA per package. Any ports not used for

controlling the LEDs can be used for general purpose

input/output expansion.