How to choose a switching power supply What working mode does the switching power supply have?
When decorating wires, you should also pay attention to the choice of power switches. After all, there are many power switches, and they correspond to different voltage ranges, power, load characteristics, and so on. The following describes how to choose a switching power supply and what working modes of the switching power supply. In the process of selecting a switching power supply, you can pay attention to these problems, and then choose a regular switching power supply product as much as possible, so that the effect will be much better.
How to choose a switching power supply
When choosing a switching power supply, consider the input voltage range, appropriate power, load characteristics, and operating ambient temperature.
1. Select the appropriate input voltage range. Taking AC input as an example, the commonly used input voltage specifications are 110V and 220V, so there are corresponding three specifications of 110V, 220V AC switching, and universal input voltage (AC: 85V-264V). The input voltage specification should be selected according to the region of use.
2. Select the appropriate power. The switching power supply consumes a part of the power during operation and releases 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 30% 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.
If the load is a motor, light bulb or 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 inversion during shutdown should be considered.
4. In addition, it is necessary to consider the working ambient temperature of the power supply and whether there is any additional auxiliary cooling equipment. The power supply needs to derate the output when the ambient temperature is too high. Refer to the derating curve of ambient temperature to output power.
What is the working mode of the switching power supply?
Frequency, pulse width fixed mode, frequency fixed, pulse width variable mode, frequency, pulse width variable mode.
1. The former working mode is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two working modes are mostly used for switching regulated power supply.
2. In addition, the output voltage of the switching power supply also has three working modes: direct output voltage mode, average output voltage mode, and amplitude output voltage mode.
3. Similarly, the former working mode is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two working modes are mostly used for switching regulated power supply.
According to the way the switching devices are connected in the circuit, the switching power supply can be roughly divided into three categories: series switching power supply, parallel switching power supply, and transformer switching power supply. Among them, transformer switching power supply (hereinafter referred to as transformer switching power supply) can be further divided into: push-pull type, half-bridge type, full-bridge type, etc.; according to the excitation of the transformer and the phase of the output voltage, it can be further divided into: forward excitation type , flyback, single-excitation and dual-excitation, etc.; if it is divided into use, it can be divided into more types.
The above introduction is how to choose a switching power supply and what working mode of the switching power supply. When choosing a power switch, you still need to know the voltage range and appropriate power. If it is a relatively high voltage, you must also understand the load capacity of these materials. In addition, in fact, the switch has a variety of working modes, including fixed frequency, pulse width, etc., so it should be selected according to the scope of use of the family.