1. Select the appropriate input voltage range: Take AC input as an example, the commonly used input voltage specifications are AC110V, AC220V, so correspondingly there are 110V, 220V AC switching, and universal input wide voltage (AC: 95V-264V) three kinds Specification. The input voltage specification should be selected according to the region of use.

2. Select the appropriate power supply: The switching power supply will consume a part of the power during operation and release it in the form of heat. In order to prolong the life of the power supply, it is recommended to choose a model with an output power rating of 25% more.

3. Consider the load characteristics: In order to improve the reliability of the system, it is recommended that the switching power supply work at 50%-80% load, that is, if the power used is 20W, a switching power supply with an output power of 25W-40W should be selected.

4. If the load is a motor, a light bulb or a capacitive load, the starting current is large when the machine is turned on, and a suitable power supply should be selected to avoid overload. If the load is a motor, the voltage inversion during shutdown should be considered.

5. In addition, it is necessary to consider the working environment temperature of the power supply and whether there are additional auxiliary cooling devices. The power supply needs to derate the output in an excessively high working environment. It is necessary to refer to the derating curve of the working ambient temperature on the output power.

6. Select various functions according to the application requirements: Protection functions: Over Voltage Protection (OVP), Over Temperature Protection (OTP), Over Load Protection (OLP), etc. Application functions: signal function (normal power supply, power supply failure), remote control function, telemetry function, parallel function, etc. Special features: power factor correction (PFC), uninterruptible power supply (UPS).

7. Select the required safety regulations and electromagnetic compatibility (EMC) certification: According to the usage, determine the required output voltage and current; the size, installation method and installation hole position of the power supply; there are several outputs, whether each output is Electrical isolation is required; input voltage range; according to the ambient temperature, the derating degree of the switching power supply, power supply power; whether certification and safety standards are required; the cooling method of the power supply: natural cooling or forced air cooling; electromagnetic compatibility standards.

8. Try to use the manufacturer's standard power supply, including standard size and output voltage. In this way, the delivery time is faster; on the contrary, the special size and output voltage will prolong the delivery time and increase the cost.

9. Choose the brand, as the heart of electronic equipment, switching power supply plays a vital role in the safe and reliable operation of electronic equipment.