Semtech SC446高效多串WLED驱动方案

Semtech公司的SC446是集成了升压转换器的高效多串WLED驱动器,输入电压从4.5V到27V,最大输出电压36V,内部功率开关为2.5A,能驱动3串多达30个WLED,每串电流100mA,串与串的电流匹配典型值为2%,整体效率大于90%,主要用在中型LCD屏,笔记本电脑显示,汽车导航显示和手提媒体播放器.本文主要介绍SC446主要特性和典型应用电路.

The SC446 is a high-efficiency multiple string WLED driver with an integrated boost converter. It operates over a wide input range from 4.5V to 27V with a maximum out- put voltage of 36V and a 2.5A internal power switch. It can drive up to thirty WLEDs in 3 strings with current up to 100mA per string. The string-to-string current matching is 2% typical, 3% maximum. The overall efficiency is greater than 90% due to the low current sense voltage and a low-impedance internal power switch. The wide PWM dimming range boasts a ratio of 500: 1.

The 700kHz switching frequency enables the user to optimize the external component sizes for efficiency. When there are fewer than 10 LEDs in each string, users can ad-just the output voltage protection yielding an allowable

reduction in associated costs, size and voltage ratings of the output capacitor.
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