HT7938

HT7938 High Current and Performance White LED Driver Features · Efficiency up to 85% at VIN=3.6V, 9LEDs, · Tiny inductor and capacitors · Up to 9 strings White-LED · Tiny 6-lead SOT23-6 package · Built in OVP, OCP, OTP, UVLO protection ILED=20mA · 1.2MHz fixed switching frequency · Low Standby Current: 0.1mA, VEN=0V (typ.) · Matches LED current Applications · Cellular phones · PDAs · DSCs · GPS · Handheld devices · White LED display backlighting General Description HT7938 is high efficiency boost converter with constant current output to provide backlight in handheld devices. Series connection of LEDs provides constant identical LED currents resulting in uniform brightness. The continuous LED current is set with FB pin regulated voltage across an external sense resistor (RFB) connected from that pin to ground. The built-in open load protection prevents the damage resulting from an open circuit condition. Low 200mV feedback voltage minimizes power loss in the current setting resistor for better efficiency. HT7938 switches at rates up to 1.2MHz to allow the use of extremely small inductor and filter capacitor. Block Diagram 36V www.DataSheet4U.com Rev 1.00 1 November 11, 2009 HT7938 Pin Assignment V IN 6 O V P 5 E N 4 T o p V ie w H T 7 9 3 8 S O T 2 3 -6 -A 1 S W 2 G N D 3 F B Pin Description Pin Name EN GND I/O I ¾ Description Shutdown & Dimming control input. Don¢t allow this pin to float. Signal Ground. Feedback pin. Reference voltage. The HT7938 feedback voltag...