High Current And Performance White LED Driver
HT7938 High Current and Performance White LED Driver
Features
· Efficiency up to 85% at VIN=3.6V, 9LEDs, · Tiny inductor...
Description
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...
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