HT7945 -- White LED Backlight Driver
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
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.
- 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
- 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