原标题：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.

　　The device includes a frequency jitter function which helps to reduce EMI power supply emissions. from damage should the LEDs be short circuited. .

　　The device requires a minimum number of external standard components and is available in an 8-pin NSOP package for small area PCB applications.

　　HT7L4091主要特性：

　　●●Input supply AC voltage range: 100V~240V

　　●●Ultra Low Power-on Start-up current < 30μA

　　●●Integrated 25V Zener diode internally connected to VIN pin

　　●●5V LDO output voltage with 6mA driving current for external components

　　●●Frequency jitter function for enhanced EMI performance

　　●●Efficiency > 85%

　　●●Under Voltage Lockout Function - UVLO

　　●●Current mode operation with cycle-by-cycle current limiting

　　●●Over Temperature Protection Function

　　●●High-current FET Drive Output

　　●●Linear and PWM Dimming Function

　　●●Enhanced Short Circuit Protection Function

　　HT7L4091应用：

　　●●AC/DC and DC/DC Power control For High Power LED Lighting

　　●●RGB back lighting LED driver

　　●●Flat Panel Displays Back Lighting

　　●●General Purpose Constant Current Source

　　●●Signage and Decorative LED lighting

　　●●Battery Chargers

　　图1。HT7L4091方框图

　　应用电路材料清单：