Holtek HT7L4091通用高亮LED照明控制方案
Holtek公司的 HT7L4091是用于高亮LED照明控制的通用PWM控制器，是逐周期电流控制、峰值电流控制法结合固定关闭时间的控制芯片。HT7L4091包含了LED开路保护、过温度保护、过低电压保护，以及加强的短路保护功能。适用于LED灯管、灯泡等通用照明；也适用于广告广告牌背光、大尺寸LCD背光等不同应用。本文介绍了HT7L4091主要特性，方框图以及多种典型应用电路。
HT7L4091 ：Universal Step-Down PWM Control For High Brightness LED Lighting Control
The HT7L4091 device provides a low-cost solution for active current mode PWM controls of High Intensity LED drive systems supplied by either AC or DC line power lines. The device operates in constant off-time mode which is suitable for buck LED drivers. The low start-up and operating currents provides flexible power requirements for high efficiency or low cost applications. The switch frequency off-time can be programmed using an external resistor. The peak current mode control achieves good output current regulation without requiring loop compensations for a wide range of input voltages.
Included in the device is a PWM dimming input which can accept an external control signal with a duty ratio from 0 to 100%. The output current can be programmed from 0 to 250mA by applying an external control voltage on the linear dimming control input.
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