As the heart of electronic devices, switching power supply plays a vital role in safe and reliable operation of electronic equipment. So what should we pay attention to when choosing switching power supply?

1. Choose the appropriate input voltage range. In the AC input, for example, commonly used input voltage specifications are 110V, 220V, so there will be a corresponding 110V, 220V AC switch, and a universal input voltage (AC: 85V-264V) three specifications. Input voltage specification should be selected according to the region.

2. Select the appropriate power. Switching power supply will consume a part of power, and then released in the form of heat. In order to increase the life of power supply, it suggested the use of more than 30% of the rated output power of the types.

3. Consider load characteristics. To improve the reliability of the system, it proposed switching power supply loads 50% -80% better, assuming the power used was 20W; we should use the output power of 25W-40W switching power supply. If the load is a motor, light bulb or capacitive load power, the current when starting instantly is large, you should choose the appropriate power supply in order to avoid overloading. The voltage flow back when downtime should be considered if the load is the motor.

4. Also need to consider the ambient temperature of the power supply working, and whether there is additional cooling equipment. Require output power derating when at high ambient temperature. Need to refer to the ambient temperature derating curve of output power.

5. Select the individual functions according to the application:
Protection: over-voltage protection (OVP), over-temperature protection (OTP), overloads protection (OLP) and so on.
Application features: Signal function (normal power supply, power supply failure), remote control, telemetry, parallel functions.
Special features: power factor correction (PFC), Uninterruptible Power Supply (UPS)

6. Select the desired safety and electromagnetic compatibility (EMC) certification. Depending on the application, set the desired output voltage and current; the size, mounting method and mounting holes of the power supply; how many outputs there are, whether each output electrical isolation is required; input voltage range; according to the ambient temperature, determine the derating level and source power; whether need certification and safety standards; cooling power: natural cooling or forced air cooling; electromagnetic compatibility standards.

7. Try to choose standard power supply of manufacturer, including standard size and output voltages so that will have faster delivery time; on the contrary, special sizes and output voltage, will extend delivery time, increasing the cost.