Holtek公司的 HT7L4091是用于高亮led照明控制的通用PWM控制器，是逐周期電流控制、峰值電流控制法結(jié)合固定關(guān)閉時間的控制芯片。HT7L4091包含了LED開路保護(hù)、過溫度保護(hù)、過低電壓保護(hù)，以及加強的短路保護(hù)功能。適用于LED燈管、燈泡等通用照明；也適用于廣告廣告牌背光、大尺寸LCD背光等不同應(yīng)用。本文介紹了HT7L4091主要特性，方框圖以及多種典型應(yīng)用電路。

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應(yīng)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

圖1。HT7L4091方框圖

圖2。HT7L4091典型應(yīng)用電路

圖3。HT7L4091沒有輸入大電容的應(yīng)用電路

圖4。HT7L4091高效應(yīng)用電路

圖5。HT7L4091 BJT電源應(yīng)用電路

應(yīng)用電路材料清單：