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.