LP3944 Datasheet | National Semiconductor

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 mand 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 m A per pin and 200 m A per package. Any ports not used for controlling the LEDs can be used for general purpose input/output expansion. Features n n n n 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) Key Specifications n 8 LED driver (multiple programmable states - on, off, input, and dimming at a specified rate) n 8 Open drain outputs capable of driving up to 25 m A per LED Applications n n n n n n Customized flashing LED lights for cellular phones Portable Applications Digital Cameras Indicator Lamps General purpose I/O expander Toys Typical Application Circuit © 2003 National Semiconductor Corporation DS200853 .national. LP3944 Pin Out (Top View) See NS Package Number SQA24A LP3944 Pin Description Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 LED0 LED1 LED2 LED3 LED4 LED5 LED6 LED7 GND NC NC NC NC NC NC NC NC RST SCL SDA VDD A0 A1 A2 Name Output of LED0 Driver Output of LED1 Driver Output of LED2 Driver Output of LED3 Driver Output of LED4 Driver Output of LED5 Driver Output of LED6...