1, choose the appropriate input voltage range: take AC input as an example, the commonly used input voltage specifications are AC110V, AC220V, so the corresponding 110V, 220V AC switching, as well as the general input wide voltage (AC: 95V-264V) three specifications. The input voltage specification should be selected according to the area of use.
2, choose the right power supply: switching power supply will consume a part of the power at work, and in the form of heat release. In order to increase the life of the power supply, it is recommended to choose more than 25% of the rated output power.
3, considering 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 is better, that is, assuming the power used is 20W, the switching power supply with the output power of 25W-40W should be selected.
4. If the load is motor, bulb or capacitive load, when the startup current is large at the moment of startup, the appropriate power supply should be selected to avoid overload. If the load is the motor should be considered when the shutdown voltage backfill.
5. In addition, it is necessary to consider the working environment temperature of the power supply and whether there is additional auxiliary heat dissipation equipment. The output of the power supply needs to be reduced in the excessively high working environment. It is necessary to refer to the reduction curve of the working environment temperature on the output power.
6, according to the application needs to choose the function: protection function: over voltage protection (OVP), over temperature protection (OTP), over load protection (OLP), etc. Application functions: signal function (power supply normal, power supply failure), remote control function, telemetry function, parallel function, etc. Special function: power factor correction (PFC), continuous power (UPS).
7, the choice of safety regulations and electromagnetic compatibility (EMC) certification: according to the use of the situation, set the required output voltage and current; Power supply size, installation method and installation hole position; There are several outputs, each output need electrical isolation; Input voltage range; According to the ambient temperature, decide the degree of switching power supply reduction, power supply power; Whether certification and safety standards are required; Power supply cooling mode: natural cooling or forced air cooling; Electromagnetic compatibility standards.
8, try to choose the manufacturer's standard power supply, including standard size and output voltage. In this way, the delivery time is faster. On the contrary, special size and output voltage will extend the delivery time and increase the cost.
9, the choice of brand, switching power supply as the heart of electronic equipment, electronic equipment is relatively safe and reliable operation has a vital role.