A Few Things About Switching Power Supplies

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A Few Things About Switching Power Supplies [Copy link]

I believe that those who have DIY experience have chosen switching power supplies for their own works (such as making Prusa i3 3D printers, LED dot matrix screens). But sometimes, poor-quality switching power supplies have also caused us trouble, such as burning the internal or even onboard electronic components of the switching power supply due to load mismatch. So today, the editor will take you to learn about a few things about switching power supplies to help you choose switching power supplies more conveniently. The picture shows a common external switching power supply The picture shows a common built-in switching power supply 1. 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; how many outputs there are, whether each output needs electrical isolation; input voltage range; according to the ambient temperature, determine the degree of derating of the switching power supply and the 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. 2. Try to use the standard power supply of the power adapter manufacturer, including standard size and output voltage. This will shorten the delivery time; on the contrary, special size and output voltage will extend the delivery time and increase the cost. 3. Select various functions according to the application requirements: Protection function: overvoltage protection (OVP), overtemperature protection (OTP), overload protection (OLP), etc. Application function: signal function (normal power supply, power failure), remote control function, telemetry function, parallel function, etc. Special function: power factor correction (PFC), uninterruptible power supply (UPS) 4. 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, assuming that the power used is 20W, a switching power supply with an output power of 25W-40W should be selected. If the load is a motor, a light bulb or a capacitive load, the current is large when the power is turned on, and a suitable power supply should be selected to avoid overload. If the load is a motor, the voltage backflow should be considered when the power is stopped. 5. In addition, the working environment temperature of the power supply and whether there are additional auxiliary heat dissipation equipment should be considered. The power supply needs to be reduced in output when the ambient temperature is too high. Refer to the derating curve of ambient temperature for output power. 6. Choose the appropriate input voltage range. Taking AC input as an example, the commonly used input voltage specifications are 110V and 220V, so there are three specifications: 110V, 220V AC switching, and universal input voltage (AC: 85V-264V). The input voltage specification should be selected according to the area of use. 7. Choose the appropriate power. The switching power supply consumes part of the power when working and releases it in the form of heat. In order to increase the life of the power supply, it is recommended to choose a model with 30% more output power rating.