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Vatican the switching frequency of the AC-DC switching power supply module?(3)


power module

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 Marine boost voltage power supply equipment will be reduced to the maximum, which is not conducive to miniaturization. When the switching Marine boost voltage 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.

input protection circuit
General module power products have built-in filters, which can meet the requirements of general power supply applications. If a more demanding power system is required, an input filter network should be added. An LC or π-type network can be used, but care should be taken to choose a smaller inductance and larger capacitance as much as possible.
In order to prevent the transient high voltage of the input power supply from damaging the power supply of the module, it is recommended that the user connect a transient absorption diode at the input end and use it with a fuse to ensure that the module is within a safe input voltage range. In order to reduce common-mode noise, Y (Cy) capacitors can be added, and a few nf high-frequency capacitors are generally selected. R is a fuse, D1 is a protection diode, and D2 is a transient absorption diode (P6KE series).

2. Vatican Disadvantages of choosing an AC-DC control IC with a switching frequency higher than 135K

When testing electronic and electrical equipment, the electronic and electrical equipment shall be tested for conducted interference voltage emission at its Marine boost voltage 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 Marine boost voltage power supply is close to 150K, and the more difficult it is to deal with the conducted disturbance.