HT7945 -- White LED Backlight Driver

General Description

The HT7945 is a high efficiency DC-DC controller which can drive multiple WLEDs connected in a series/parallel configuration. The device has a wide input voltage, ranging from 4.5V to 26V, and an adjustable 15mA to 30mA WLED current, setup using an external resistor. In total, the device can support up to 88 WLED.

In addition, eight current sink regulators provide ±1.5% high precision current matching between strings. The brightness can be adjusted by an external PWM signal with frequency up to 20kHz. Once an open/short string is detected, that string is disabled while the other strings continue to operate normally.

Other protection includes soft-start, under voltage lockout, programmable over voltage protection, switch current limit and thermal shutdown.

The HT7945 is supplied in a QFN 24 pin 4mm x 4mm tiny footprint package type.

Features

  • Max input voltage: 26V
  • Integrated Power Mosfet
  • Output voltage up to 40V driving 11 series
    LEDs – LED Vf(max)=3.5V per string – absolute max rating up to 44V
  • Channel Phase Shift PWM Dimming
  • Drives up to 12 LED strings under Vf(max)=3.3V condition
  • Low string feedback voltage: 0.8V at 20mA LED current
  • Switching frequency: 500kHz/1MHz
  • 8-string constant current output
  • LED current adjustable from 15mA to 30mA
  • ±1.5% current matching between strings
  • PWM dimming control
  • 1% minimum dimming duty-cycle at 2kHz
  • Integrated soft start function
  • LED failure detection: open and short circuit
  • Capacitor type: ceramic
  • Protection: OVP, OTP, UVLO, SW current limit
  • Small 24-pin outline package: 4mm x 4mm,
    thin QFN type

Technical Document

Other Information