HT7938A Datasheet | Holtek Semiconductor

Feature - Efficiency up to 90% at VIN=4.0V, 5S2P, ILED=20m A - 1.2MHz fixed switching frequency - Low standby current: 0.1m A (typ.) at VEN=0V - Matches LED current - Tiny inductor and capacitors - EN pin dimming frequency up to 200k Hz - Up to 10 strings White-LED (LED VF(Max.)=3.5V) - Tiny 6-lead SOT23-6 package - Built in OVP, OCP, OTP, UVLO protection Applications - Cellular phones - PDAs - DSCs - Handheld devices - White LED display backlighting General Description The HT7938A is high efficiency boost converter with constant current output for backlight applications in handheld devices. Using a series connection of LEDs provides constant identical LED currents resulting in uniform brightness. The continuous LED current is set using the device FB pin regulated voltage across an external sense resistor, RFB, connected between this pin and ground. The integrated open load protection feature prevents device damage resulting from open circuit load conditions. A low 300m V feedback voltage minimises power losses in the current setting resistor which provides enhanced efficiency. The HT7938A has a dimming frequency of up to 200k Hz, which has excellent linear performance over this dimming frequency range. The device switches at rates of up to 1.2MHz to allow the use of extremely small inductors and filter capacitors. Selection Guide Part No. HT7938A Package SOT23-6 Note: Both lead free and green pound devices are available. Marking 38A-3 (VFB=300m V) Rev. 1.30 August 23, 2016 Block Diagram O VP O VP P ro te c t 39V R am p 1 .2 M H z O SC O TP V IN U V L O = 2 .1 V SW Pin...