Freescale MC34845六路LED背景光驱动方案

Freescale 公司的MC34845是集成了电路的六路LED背景光驱动器,工作电压从5.0V到21V,能驱动多达6串,每串16个LED.6串LED的电流误差最大为±2%. MC34845的输出电压高达60V,集成了2.0A的FET,具有OTP,OCP,UVLO故障检测和LED短路/开路保护,LED电流在3.0mA和30mA之间编程,主要用在笔记本电脑,上网本,手提DVD播放器,小屏幕电视,工厂业和医疗显示器等.本文介绍了MC34845的主要特性,方框图,典型应用电路以及评估板的主要特性,详细电路图和所用材料清单.

Low Cost 6 Channel LED Backlight Driver with Integrated Power Supply

The 34845 series represents high efficiency LED drivers for use in backlighting LCD displays from 10” to 17”+. Operating from supplies of 5.0 V to 21 V, the 34845 series is capable of driving up to 16 LEDs in series in 6 separate strings. The LED current tolerance in the 6 strings is within ±2% maximum and is set using a resistor to GND.

PWM dimming is performed by applying a PWM input signal to the PWM pin which modulates the LED channels directly. An Enable Pin (EN) provides for low power standby. Alternatively, a single wire scheme selects power down when PWM is connected to the Wake Pin and held low.
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