100瓦特校整转换器的通用输入

　　一般描述

　　这100瓦特转换器演示了广泛的在NCP1650型特征。该芯片是能够PFC变换器控制到千瓦范围。除了优秀的功率因数，该芯片提供固定连续和断续模式中的频率操作操作。它具有多种保护功能，包括瞬时电流限制，平均电流限制，真正的功率限制。这个单位将提供400伏的稳压电源输入源的频率范围从50赫兹到60赫兹，和85 VRMS的电压范围为265 Vrms。它是完全自我包含并包括一个高电压启动电路，和偏置电源，操作的升压电感关闭。

　　Features

　　• Fixed Frequency Operation

　　• Shutdown Circuit

　　• Operation Over the Universal Input Range

　　• Multiple Protection Schemes

　　• True Power Limiting

　　• Start-Up and Bias Circuits Included

　　Circuit Description

　　Start-Up Circuit

　　The start-up circuit allows the unit to use power from the

　　input line to begin operation， and then shuts down to allow

　　operation off of the bias winding， which reduces losses in the

　　circuit.

　　The start-up circuit has three modes of operation. One is

　　used for starting the NCP1650 when the chip is functional，

　　one is for bias power during shutdown operation， and the

　　third is the off state.

　　When power is initially applied to the unit， the gate of the

　　pass transistor will be high， and the FET will be fully

　　enhanced. The current into the VCC capacitance at pin 1 will

　　be limited by the three 10 k： resistors in series with the FET.