Why is this power circuit connected like this?

灞波儿奔

Why is this power circuit connected like this? [Copy link]

The following circuit, such as the circuit 2843 in the red circle, is there any other purpose? The 1st pin of the chip is directly connected to 817.

The question is, can the RC network connected to pin 2 have any effect on pin 1?

Power supply experts, can you give us a detailed analysis?

maychang

"The question is, can the RC network connected to pin 2 have any effect on pin 1?"

C21R29 is connected to the output and inverting input of the on-chip operational amplifier. This connection obviously affects the output impedance of the on-chip operational amplifier, thereby affecting the amplifier characteristics composed of the optocoupler output transistor side and the on-chip constant current source.

Fred_1977

I haven't paid attention to switching power supplies for a long time, and I have forgotten a lot of knowledge. There are too many hardware subdivisions.

javnson

You can refer to the in-phase proportional amplifier circuit. The main consideration here is resistance, and the role of the small capacitor here can be understood as a small filter.