What are the common problems in the design of thin film switching circuits?

The connection of high impedance weak signal circuit should be as short as sampling feedback loop, and the interference and current sampling signal circuit, especially current control circuit, should be avoided as far as possible in processing. Some unexpected accidents can easily occur if the circuit is not handled well. Some skills are shown in the examples of 3843 circuit. Fig. 1 is better than Fig. 2. Observing the current waveform with oscilloscope at full load. Because the interference current limiting point is lower than the design value, there is no such phenomenon in Fig. 1. There is also a switch driver signal circuit. The switch driver resistance should be close to the switch, which can improve the reliability of the switch. This is related to the high DC impedance voltage driving characteristics of power MOSFET.