采用墙上交流电压工作的大功率电源都要使用大的输入滤波电容。必须限制这些电容的浪涌电流,否则,电源就可能触发交流断路器,或者造成整流器、滤波扼流圈或PCB(印刷电路板)走线的损坏。本例中的电路是在电容的充电路径中插入一个限流电阻。它可探测出电容何时充电到一个最小阈值电压。然后,它使用一只TRIAC(三端交流开关)将电阻短路。监控电容电压比监控输入电流更好,从而避免在可能造成浪涌限流 The use of high-voltage power supply wall AC voltage must use a large input filter capacitor. The inrush current of these capacitors must be limited or the power supply may trip the AC circuit breakers or cause damage to the rectifier, filter choke, or PCB (printed circuit board) traces. The circuit in this example is to insert a current-limiting resistor in the capacitor’s charging path. It detects when the capacitor is charged to a minimum threshold voltage. Then, it uses a TRIAC (three-terminal AC switch) to short-circuit the resistor. Monitoring the capacitor voltage is better than monitoring the input current, thus avoiding possible surge limiting