Holtek HT7955电视WLED背光驱动解决方案 - 消费电子 - 电子工程网
The HT7955 is a high efficiency DC-DC controller drives a number of WLEDs connected in series/ parallel configuration and has a wide input voltage range from 10V to 26V, and adjustable 60mA to 80mA WLED current by external resistor. In total, the device can support up to 80 WLED.
In addition, six current sink regulators provide ±2.5% high precision current matching between strings. The brightness can be adjusted by external PWM up to 2kHz. Once an open/short string is detected, the string is disabled while other strings operate normally.
Other protecting includes soft-start, under voltage lockout, programmable over voltage protection, WLED current limit, switch current limit and thermal shutdown.
The HT7955 is packaged with a tiny footprint package of 48-Pin 7x7x1.0mm TQFP-EP package.
Allowable max input voltage: 26V
Built-in Power MOSFET
Output voltage up to 40V driving 10 series LEDs – LED Vf(max)=3.5V per string – absolute max rating up to 44V
Channel Phase Shift PWM Dimming
Direct PWM Dimming without Phase Shift
Operate up to 11 strings LED at Vf(max.)=3.3V condition
Low string feedback voltage: 0.5V at 80mA LED current
Switching frequency: 200kHz/400kHz
8-string constant current output
LED current adjustable from 60mA to 80mA
±2.5% current matching between strings
Dimming control using PWM
1% minimum dimming duty-cycle at 2kHz
Built- in Soft start
LED failure detection: open and short circuit
Capacitor type: ceramic
•rotection: OVP, OTP, UVLO, LX current limit
LED backlights for LCD monitor and LCD TV