Holtek公司的HT7A4016是低功耗寬溫度范圍的通用電流模式PWM控制器,滿足能量之星2.0規范,起動電流低于20uA和很低工作電流,ESD保護大于3kV,調整振蕩器精度±5%,內部具有斜率補償,主要用在開關電源AC/DC適配器,DC/DC降壓/升壓轉換器,LCD/LED TV的LED背光照明.本文介紹了HT7A4016主要特性,方框圖以及針對各種不同應用電路的參考設計電路.
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應用:
• Switching AC-DC Adaptors
• DC-DC Switching Buck/Boost Converters
• LED Backlights for LCD/LED TVs
圖1. HT7A4016方框圖
圖2. HT7A4016典型應用電路圖
圖3. HT7A4016恒壓升壓應用電路圖(DC/DC升壓)
圖4. HT7A4016用于背光LED驅動的DC/DC恒流升壓應用電路圖
圖5. HT7A4016 LED照明驅動的恒流降壓應用電路圖
圖6. HT7A4016恒流降壓穩壓器應用電路圖(高邊降壓)
圖7. HT7A4016初級反饋的隔離反激AC/DC轉換器電路圖 |
