Microprocessor reset circuit

Shown is the reset circuit of the Hisense KFR-25GW/06BP ​​inverter air conditioner indoor unit microprocessor. When starting up, the power supply voltage of the microprocessor rises from 0 to +5 V. During this process, the startup program may have errors. Therefore, it is necessary to start the program after the power supply voltage stabilizes . This task is implemented by the reset circuit . of. 1C1 in the figure is the reset signal generating circuit. Pin ② is the power supply terminal, and pin ① is the reset signal output terminal. The voltage is filtered (C20, C26) and then added to the reset terminal @ pin of the CPU. The reset signal has a certain delay compared with the power-on time, and the length of the delay time is related to the capacitance outside the @ pin.