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

图2。HT7L4091典型应用电路

图3。HT7L4091没有输入大电容的应用电路

图4。HT7L4091高效应用电路

图5。HT7L4091 BJT电源应用电路

应用电路材料清单：

详情请见：
http://www.holtek.com.tw/PDF/consumer/HT7L4091v100.pdf