原标题：Diodes AL8400 0.2V线性LED驱动方案

　　Diodes公司的AL8400 是0.2V五端可调节的线性LED驱动控制器,具有极好的温度稳定性和输出处理功能.工作电压从0.2V到场18V,工作温度-40度到125度C,25℃的基准电压容差为3%,可驱动双极晶体管和MOSFET,主要用在隔离的离线LED转换器,线性LED驱动器,LED信号和仪表照明.本文介绍了AL8400主要特性,AL8400主要特性, 典型应用电路图和高压应用电路,以及和离线LED驱动电路图.

　　AL8400: 0.2V LINEAR LED DRIVER CONTROLLER TARGET SPECIFICATION

　　The AL8400 is a 5-terminal adjustable Linear LED driver controller offering excellent temperature stability and output handling capability. The AL8400 simplifies the design of linear and isolated LED drivers. With its low 0.2V FB pin, it controls the regulation of LED current with minimal power dissipation when compared to traditional linear LED drivers.

　　This makes it ideal for medium to high current LED driving.

　　The AL8400 open-collector output can operate from 0.2V to 18V enabling it to drive external MOSFET and Bipolar transistors. This enables the MOSFET and Bipolar selection to be optimised for the chosen application. It also provides the capability to drive longer LED chains, by tapping VCC from the chain, where the chain voltage may exceed 18V.It is available in the space saving low profile SOT353 package.

　　AL8400主要特性:

　　• Low reference voltage (VFB = 0.2V)

　　• -40 to 125℃ temperature range

　　• 3% Reference voltage tolerance at 25℃

　　• Low temperature drift

　　• 0.2V to 18V open-collector output

　　• High power supply rejection

　　• (> 45dB at 300kHz)

　　AL8400应用:

　　• Isolated offline LED converters

　　• Linear LED driver

　　• LED signs

　　• Instrumentation illumination

　　图1.AL8400功能方框图

　　图2.AL8400典型应用电路图

　　图3.AL8400采用双极晶体管的应用电路图

　　图4.AL8400采用MOSFET的应用电路图

　　图5.AL8400离线LED驱动电路图

　　图6.AL8400输入VIN带齐纳二极管的高压应用电路图

　　图6.AL8400 VCC从LED串抽头的高压应用电路图