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Holtek公司的HT7A4016是低功耗宽温度范围的通用电流模式PWM控制器,满足能量之星2.0规范,起动电流低于20uA和很低工作电流,ESD保护大于3kV,调整振荡器精度±5%,内部具有斜率补偿,主要用在开关电源AC/DC适配器,DC/DC降压/升压转换器,LCD/LED TV的LED背光照明.本文介绍了HT7A4016主要特性,方框图以及针对各种不同应用电路的参考设计电路. The HT7A4016 is a controller IC that includes the necessary features to implement off-line or DC-DC current mode control schemes with a minimal external parts count. Internal circuits include a specially designed Mixed-Mode/Analog Interface for multi-function and multi-topology control schemes (DC-DC Buck/Boost, Off-line AC-DC), a trimmed oscillator for precise duty-cycle control under voltage lockout with a start-up current of less than 0.5mA, a wide temperature range, precise voltage reference, internal Slope Compensation and Leading-Edge Blanking. The HT7A4016 features basic system protection functions such as Cycle-by-Cycle Current Limiting and Under Voltage Lock-Out (UVLO). A Multi-Function Pin can be used as a dimming function for LED driving, and as a primary feedback control f o r Primary - Side Feed back AC - DC applications. HT7A4016主要特性: · High Performance, Low Cost Current Mode PWM Controller especially designed for Energy Star 2.0 · Very Low Startup Current (<20μA) and Operating Current · High-Voltage CMOS Process with Excellent ESD protection (>3KV) · ±5% Trimmed Oscillator for Precise Frequency Control · LEB (Leading-Edge Blanking) on CS Pin · Internal Slope Compensation · Programmable Switching Frequency · Internally Trimmed Reference with UVLO (Under Voltage Lockout) · Cycle-by-Cycle Current Limiting HT7A4016应用: · Switching AC-DC Adaptors · DC-DC Switching Buck/Boost Converters · LED Backlights for LCD/LED TVs  图1. HT7A4016方框图  图2. HT7A4016典型应用电路图  图3. HT7A4016恒压升压应用电路图(DC/DC升压)  图4. HT7A4016用于背光LED驱动的DC/DC恒流升压应用电路图  图5. HT7A4016 LED照明驱动的恒流降压应用电路图  图6. HT7A4016恒流降压稳压器应用电路图(高边降压)  图7. HT7A4016初级反馈的隔离反激AC/DC转换器电路图 |
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