The input is about 9v DC power supply, and the output is 5V voltage regulator. DC DC-DC buck circuit can be used to make a stable 5v voltage regulator power supply.
The key components of the step-down circuit are power control chip, power field tube, inductor and output diode. The PWM signal is used to control the on-time of the power tube to stabilize the output voltage, and the output power of the voltage regulator circuit is large and the stability is high.