LP3943 Datasheet, PDF (1/13 Pages) National Semiconductor (TI) – RGB/White/Blue 16-LED Fun Light Driver

November 2003
LP3943
RGB/White/Blue 16-LED Fun Light Driver
General Description
LP3943 is an integrated device capable of independently
driving 16 LEDs. This device also contains an internal pre-
cision oscillator that provides all the necessary timing re-
quired for driving each LED. Two prescaler registers along
with two PWM registers provide a versatile duty cycle con-
trol. The LP3943 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. 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 ON, OFF, or to cycle a pro-
grammed 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.
Features
n Internal power-on reset
n Active low reset
n Internal precision oscillator
n Variable dim rates (from 6.25 ms to 1.6s;
160 Hz–0.625 Hz)
Key Specifications
n 16 LED driver (multiple programmable states — on, off,
input, and dimming at a specified rate)
n 16 Open drain outputs capable of driving up to 25 mA
per LED
Applications
n Customized flashing LED lights for cellular phones
n Portable Applications
n Digital Cameras
n Indicator Lamps
n General purpose I/O expander
n Toys
Typical Application Circuit
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