Traditional Culture Encyclopedia - Traditional stories - How to calculate the starting resistance of switching power supply, is there a formula, and how to choose the input filter capacity? Thank you! ! !

How to calculate the starting resistance of switching power supply, is there a formula, and how to choose the input filter capacity? Thank you! ! !

The starting resistor of the switching power supply is connected to 300V after rectification, and it is suggested to be (300V- starting voltage of control chip)/input current of chip starting pin. Generally, the input current of the initial pin of the chip is uA level. Please check the PDF of the control chip for details. According to the past experience, my advice to you is that the starting resistance should be 680 K ~1.5 m. A small starting resistance can make the output voltage start quickly, but the standby power consumption will be reduced. As for the input filter capacitor, you can choose it according to the experience of 2uF/W, depending on the output power of your switching power supply.