North Korea the switching frequency of the AC-DC switching power supply module?(2)
North Korea Choosing the switching frequency of the LED advertising screen power supply does not mean choosing the switching frequency of the LED advertising screen power supply with a good switching frequency, but the choice is suitable for your own use. Most of the current market is like this. The frequency of the AC-DC switching LED advertising screen power supply module is between 50K and 135K, and this frequency range can meet most applications. Let's discuss it. Some of the problems that AC-DC encounters when choosing switching frequency:
1. Why generally do not choose a switching frequency lower than 50K
(6) For the module power supply, some manufacturers have a fixed resistance directly connected to the adjustable terminal (ADJ) from the factory. When using, the user must configure a potentiometer with the corresponding resistance value to replace the fixed resistance. However, it should be noted that when the adjustable terminals are in an open state, loading is never allowed.
(7) In order to achieve sufficient heat dissipation, the module power supply should be installed in a location with better air convection. Generally, when the working current of the linear power supply is above 4A, or the working current of the switching power supply is above 7A, forced air cooling should be installed. In addition, no other items are allowed on the module power supply housing.
(8) The module power supply is generally suitable for resistive-based loads. If it needs to be applied to capacitive-based or inductive-based loads, it should be explained in the order contract in advance and customized by the manufacturer.
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 LED advertising screen power supply equipment will be reduced to the maximum, which is not conducive to miniaturization. When the switching LED advertising screen 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.