HT7938A数据手册Holtek中文资料规格书

描述 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 300mV feedback voltage minimises power losses in the current setting resistor which provides enhanced efficiency. The HT7938A has a dimming frequency of up to 200kHz, 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.

特性 Features

Efficiency up to 90% at VIN=4.0V, 5S2P, ILED=20mA
1.2MHz fixed switching frequency
Low standby current: 0.1µA (typ.) at VEN=0V
Matches LED current
Tiny inductor and capacitors
EN pin dimming frequency up to 200kHz
Up to 10 strings White-LED (LED VF(Max.)=3.5V)
Tiny 6-lead SOT23-6 package
Built in OVP, OCP, OTP, UVLO protection