how to select components when designing circuits?

Switching power supply is a power supply that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output voltage. The switching power supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET. With the development and innovation of power electronic technology, switching power supply technology is also constantly innovating. At present, switching power supply is widely used in almost all electronic equipment because of its small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of today's electronic information industry.

Buck converter is a step-down non-isolated switching power supply. When the switch is turned on, the input power supplies power to the output through the inductor, and the inductor stores energy at the same time; when the switch is turned off, the inductor supplies power to the output through the freewheeling diode; This repetition can maintain the output to produce a constant voltage. Its Buck circuit topology and circuit analysis calculation.

Boost converter is a step-down non-isolated switching power supply. When the switch is turned on, the input power charges the inductor through the inductor, and the inductor stores energy; when the switch is turned off, the input power and inductor energy pass through the freewheeling diode. The output is powered; this is repeated to maintain the output at a constant voltage. Its Boost circuit topology and circuit analysis and calculation are shown in Figure 2.

Buck-Boost converter is a buck-boost non-isolated switching power supply. When the switch is turned on, the input power charges the inductor through the inductor, and the inductor stores energy; The output is powered; this repeatedly maintains the output to produce a constant negative voltage.