Linear LT3751高输入电压反激电源控制方案

Linear 公司的LT3751是高输入电压反激电源控制器,能大容量电容进行快速充电. LT3751集成了轨到轨的MOSFET栅极驱动器,能有效地工作低到4.75V的电压,输入工作电压从5V到24V. 而LT3751能在不到1秒的时间内把1000uF的电容充电到500V.因此广泛应用在高压稳压电源和电容充电器,专业闪光灯系统, 应急搜救灯,安全控制系统以及雷管等.本文介绍了LT3751主要特性,方框图以及42A电容充电器电路图, 18A非隔离高压稳压器电路图和PCB元件布线图.

The LT3751 is a high input voltage capable flyback controller designed to rapidly charge a large capacitor to a user-adjustable target voltage set by the transformer turns ratio and three external resistors. An optional feedback pin can be used to provide a low noise high-voltage regulated output.

The LT3751 has an integrated rail-to-rail MOSFET gate driver that allows for efficient operation down to 4.75V. A low 106mV differential current sense threshold voltage
accurately limits the peak switch current. Added protection is achieved with user-selectable overvoltage and undervoltage lockouts for both VCC and VTRANS. A typical application can charge a 1000μF capacitor to 500V in less than one second.

The CHARGE pin is used to initiate a new charge cycle and provides ON/OFF control. The DONE pin indicates when the capacitor has reached its programmed value and the part has stopped charging. The FAULT pin indicates when the LT3751 has shut down due to either VCC or VTRANS voltage exceeding the user-programmed supply tolerances.

主要特性:
Charges Any Size Capacitor
Low Noise Output in Voltage Regulation Mode
Stable Operation Under a No-Load Condition
Integrated 2A MOSFET Gate Driver with Rail-to-Rail Operation for VCC ≤ 8V
Selectable 5.6V or 10.5V Internal Gate Drive Voltage Clamp
User-Selectable Over/Undervoltage Detect
Easily Adjustable Output Voltage
Primary or Secondary Side Output Voltage Sense
Wide Input VCC Voltage Range (5V to 24V)
Available in a 20-Pin QFN 4mm 5mm

应用:
High Voltage Regulated Supply
High Voltage Capacitor Charger
Professional Photofl ash Systems
Emergency Strobe
Security/Inventory Control Systems
Detonators



图1.LT3751方框图



图2.LT3751 42A电容充电器



图3.LT3751 18A非隔离高压稳压器电路图



图4.LT3751应用电路PCB元件布线图