PC112

PC112/PC113 Version : A.001 Issue Date : 2004/10/01 File Name : SP-PC112/PC113-A.001.doc Total Pages: 14 Step Up Converter for White LED Driver 9 7 1 SILICON TOUCH TECHNOLOGY INC. 9-7F-1, Prosperity Road I, Science Based Industrial Park, Hsin-Chu, Taiwan 300, R.O.C. Tel：886-3-5645656 Fax：886-3-5645626 SILICON TOUCH TECHNOLOGY INC. PC112/PC113 General Description PC112/PC113 is a compact, high-efficiency step-up DC-DC converter which drives 2-6 series white LEDs with constant current from 3V to 5V. Extremely low shutdown power supply current ensures the high efficiency of battery system. The PC113 works at 500KHz, allowing the application of tiny external components. Low feedback voltage and hence minimal input current from the battery extends battery life. Built-in N-channel power switches optimize the layout area of PCB. Since PC112/PC113 drives series LEDs, it regulates the light intensity uniformly. With a single external resistor or PWM signal, users can easily set the LED current and LED brightness. While output loading is open, likes the case of LEDs failure, the duty cycle of the DC-DC converter will increase rapidly, causing high output voltage to damage the circuit. To avoid this situation, a Zener diode should be connected to the DC-DC converter’s output to clamp the output voltage in most applications. However, PC113 has built-in the over-voltage protection circuit to protect the output circuit and thus eliminates the need of the external Zener diode. PC112/...