Sweden the switching frequency of the AC-DC switching power supply module?(3)
We know that the lower the switching frequency, the smaller the switching loss, but on the other hand, with the reduction of the switching frequency, the volume of the 24V input power supply equipment will be reduced to the maximum, which is not conducive to miniaturization. When the switching 24V input power supply is working, due to the switching of the switching device, the magnetic core will vibrate, and the frequency range that the human ear can hear is about 20~20000Hz. In order to avoid audible noise, we usually choose to stay away from the 20 frequency KHz.
2. Sweden Disadvantages of choosing an AC-DC control IC with a switching frequency higher than 135K
The synchronous rectification technology uses field effect transistors (MOSFETs) with small on-resistance and low withstand voltage to replace ordinary rectifier diodes. Since the synchronous rectifier MOSFET has the characteristics of low on-resistance (generally only a few mΩ), small leakage current when blocking, and high switching operating frequency, it can greatly reduce the power consumption of the power rectifier part and make the working efficiency of the power system obvious. It is improved, but the realization of synchronous rectification is more complicated than diode rectification in specific applications. In the application of low voltage and high current output of switching power supply, synchronous rectification technology has a good application prospect.
When testing electronic and electrical equipment, the electronic and electrical equipment shall be tested for conducted interference voltage emission at its 24V input power supply terminal. Although the test frequency bands of different standards are different, the test frequency bands of most products are 150K~30M. It can be seen from the lower limit of the test frequency that the operating frequency of the switching 24V input power supply is close to 150K, and the more difficult it is to deal with the conducted disturbance.