移动通信
关键词: Holtek , HT7955 , 电视 , WLED背光驱动
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.
2012-9-17 21:43:21 上传
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.
HT7955主要特性:
• 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
HT7955应用:
• LED backlights for LCD monitor and LCD TV
2012-9-17 21:43:23 上传
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