Switch Mode Power Supply (SMPS), also known as switching power supply

2019-07-02 22:31:58

Switch Mode Power Supply (SMPS), also known as switching power supply, switching converter, is a high-frequency power conversion device, which is a kind of power supply. Its function is to convert a level of voltage through different forms of architecture to the voltage or current required by the user. Most of the input of the switching power supply is an AC power source (such as a commercial power supply) or a DC power supply, and the output is mostly a device that requires a DC power source, such as a personal computer, and the switching power supply converts the voltage and current between the two.

 

The switching power supply is different from the linear power supply. The switching transistors used by the switching power supply are mostly switched between the full-on mode (saturation zone) and the fully-closed mode (cut-off zone). Both modes have low dissipation characteristics. The conversion will have higher dissipation, but the time is short, so it is more energy efficient and produces less waste heat. Ideally, the switching power supply itself will not consume power. Voltage regulation is achieved by adjusting the time that the transistor is turned on and off. Conversely, in the process of generating an output voltage, the linear power supply operates in the amplification region and consumes power itself. The high conversion efficiency of the switching power supply is one of its advantages, and because the switching power supply has a high operating frequency, a small-sized, light-weight transformer can be used, so the switching power supply will be smaller than the linear power supply and the weight will be lighter.

 

If the high efficiency, volume and weight of the power supply are the key points, the switching power supply is better than the linear power supply. However, the switching power supply is more complicated, and the internal transistors will switch frequently. If the switching current is still processed, noise and electromagnetic interference may be generated to affect other devices, and if the switching power supply is not specially designed, the power factor of the power supply may not be high.