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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、峰值電流控制法結合固定關閉時間的控制芯片。HT7L4091包含了LED開路保護、過溫度保護、過低電壓保護，以及加強的短路保護功能。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背光等不同應用。本文介紹了HT7L4091主要特性，方框圖以及多種典型應用電路。 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典型應用電路
圖3。HT7L4091沒有輸入大電容的應用電路
圖4。HT7L4091高效應用電路
圖5。HT7L4091 BJT電源應用電路 應用電路材料清單：
詳情請見： http://www.holtek.com.tw/PDF/consumer/HT7L4091v100.pdf |
