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.