Allegro A8501 4路x100mA WLED驱动方案
Allegro公司的A8501是4路x100mA WLED/RGB LED驱动器，它集成了升压转换器和四个100mA电流沉。LED通路可吸收高达400mA电流。单电源8-21V工作，能经收高达40V电压。600kHz 到2.2MHz工作频率，可驱动4串，每串9个LED（36个LED），4000：1调光，主要用于GPS导航系统，汽车娱乐系统，照相机显示器，手提DVD播放器和工业LCD显示器。本文介绍A8501主要特性，方框图，多种应用电路和调光电路以及典型SEPIC转换器应用电路。
2 MHz, 4 Channel×100 mA WLED/RGB Driver with Output Disconnect
The A8501 is a multioutput WLED/RGB driver for backlighting medium-size displays. The A8501 integrates a boost converter and four 100 mA current sinks. LED channels can be tied together for up to 400 mA sink capability. It can work from a single power supply of 8 to 21 V and withstand up to 40 V. The boost converter is a constant frequency, current-mode converter.
Operating frequency can be set to 2 MHz in order to avoid interference with the AM radio band. The integrated boost DMOS switch is rated for 40 V at 3.6 A. PWM dimming allows LED currents to be controlled at up to a 1000:1 ratio. Additional 4:1 dimming can be achieved by using the DIM pin.
The A8501 provides protection against output connector shorts through an integrated output disconnect switch. An optional external thermistor can be used to limit LED current based on panel temperature...
