NS LM3423环境光自适应LED驱动方案

NS的LM3421/LM3423是恒流LED驱动器的N沟控制器,可配置成降压,升压,降-升压(反激)或SEPIC,输入电压可高达75V,非常适合各种情况下的LED照明应用. 采用LM3423的环境光自适应LED驱动器采用4.5V-12V的电池输入,在15-20V时LED保持100mA的恒流,效率高达85%,PWM标LED调光高达25kHz,可使LED的亮度正比与环境光,从而延长了电池使用寿命.本文介绍了LM3421/LM3423的主要特性,方框图以及相应的应用电路.同时还介绍了采用LM3423的环境光自适应LED驱动器的主要特性,详细的电路图和材料清单(BOM).

LM3421, LM3423: N-Channel Controllers for Constant Current LED Drivers
The LM3421/LM3423 devices are versatile high voltage LED driver controllers. With the capability to be configured in a Buck, Boost, Buck-Boost (Flyback), or SEPIC topology, and an input operating voltage rating of 75V, these controllers are ideal for illuminating LEDs in a very diverse, large family of applications.

Adjustable high-side current sense with a typical sense voltage of 100mV allows for tight regulation of the LED current with the highest efficiency possible. Output LED current regulation is based on peak current-mode control with predictive Off-Time Control. This method of control eases the design of loop compensation while providing inherent input voltage feed-forward compensation.
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