A switching power supply is a power supply that uses modern power electronics technology to control the time ratio of the switch tube to open and close to maintain a stable output voltage. The power switch supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET.
The working principle of a switching power supply is that when the switch element is in an open circuit state, the current in the circuit cannot flow, so that the voltage and power in the circuit are zero; when the switch element is in a closed state, the current in the circuit can flow, so that the voltage and power in the circuit reach a predetermined value.
Compared with a switching power supply circuit and a linear power supply, the cost of both increases with the increase of output power, but the growth rate of the two is different.
The cost of a linear power supply is higher than that of a dc switching power supply at a certain output power point, which is called the cost reversal point.
With the development and innovation of power electronics technology, the dc switching power supply technology is also constantly innovating, and this cost reversal point is increasingly moving towards the low output power end, which provides a broad development space for switching power supplies.
Working characteristics of switching power supplies
1. Small size and light weight: Since there is no power frequency transformer, the volume and weight are only 20-30% of the linear power supply.
2. Low power consumption and high efficiency: Power transistors work in a switching state, so the power consumption on the transistor is small and the conversion efficiency is high, generally 60-70%, while the linear power supply is only 30-40%.
3. Simple structure and high reliability: easy maintenance, and the current ripple rate can be easily made relatively low.
The advantage of the define switching power supply is that it can quickly and conveniently control the switch of the power supply, and can effectively save energy. The disadvantage is that the service life of the 12v switch power supply is short and it is easily affected by the external environment, such as humidity and temperature.
In general, we only think about buying a circuit power supply switching when the product we use fails. We can directly take the previous power supply to find some professional companies selling switching power supplies to see if there is a model or parameter that can be replaced.
The specifics can be carried out from the following aspects
Switching power supply input and output type
It can be roughly divided into: ①AC/DC ②DC/DC ③DC/AC Note: AC is alternating current, DC is direct current, such as AC/DC is alternating current input and direct current output.
Input voltage
Common input voltage specifications include 110V, 220V, and universal input voltage (AC: 85V-264V). The input voltage specification should be selected according to the area of use.
Output voltage and current
The voltage should be the same when selecting a switching power supply, followed by the current. The rated current of the 12v power supply with switch must be greater than the maximum current of the load.
For example, if your circuit is 15V, 60mA, it is generally recommended to select a power supply of more than 100mA. In addition, as long as the voltage is the same, no matter how much greater the current provided by the dc dc switching power supply is than the actual use, the circuit will only pass so much and will not be damaged.
Switching power supply function
Voltage-stabilized switching power supply: the input voltage and output voltage are rated at a certain value
SCR switching power supply: the output voltage can be changed by adjusting the input voltage
Adjustable switching power supply: within the rated range of input voltage, the output voltage and current can be adjusted by means of potentiometers, etc.
Switching power supply load characteristics
In order to improve the reliability of the system, it is recommended that the dc dc switching power supply work at 50%-80% load, that is, choose a model with an output power rating of about 30% more.
For example, 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, a 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.
Ambient temperature
It is also necessary to consider the working ambient temperature of the dc dc switching power supply and whether there are additional auxiliary heat dissipation equipment. The power supply needs to be derated at too high ambient temperature. The derated curve of ambient temperature on output power needs to be referred to.
Finally, the dc dc switching power supply can basically be used for several years. Of course, this is based on the purchase of regular products to ensure a long service life. When purchasing, confirm with the seller. If there is a problem within one month of use, the other party must also provide unconditional replacement of new products or help us repair.
It is not recommended to choose non-branded three-no products. The quality of such products is likely to have problems, and may even threaten our safety. Merchants who can provide better after-sales service also have better quality assurance. For example, the quality of our brand IDEALPLUSING is worth guaranteeing.
