Cambodia the switching frequency of the AC-DC switching power supply module?(4)

When testing electronic and electrical equipment, the electronic and electrical equipment shall be tested for conducted interference voltage emission at its 48V 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 48V input power supply is close to 150K, and the more difficult it is to deal with the conducted disturbance.

Due to the wide variety of integrated circuits used in communication equipment, their power supply voltages are also different. In the communication power supply system, a high-frequency DC-DC isolation module power supply with high power density is used, which is converted from the intermediate bus voltage (usually 48V DC) to Various DC voltages are required, which can greatly reduce losses, facilitate maintenance, and are very convenient to install and increase. Generally, it can be directly installed on the standard control board, and the requirement for the secondary power supply is high power density. Due to the continuous increase of communication capacity, the capacity of communication power supply will also continue to increase.

3. What special applications are required for the power switching frequency?

In some special cases, the circuit operation is more sensitive to the switching noise of the 48V input power supply. Such as power carrier, wireless communication, wireless identification, etc. The 48V input power supply requirements for power carrier applications are as follows.

At present, the power carrier is mainly used for intelligent carrier in the home, remote meter reading system, and remote street lamp control system. The use range of the carrier frequency of power lines in my country is 9KHz ~ 500KHz, and the carrier bandwidth is 4KHz. The development of power carrier is very limited due to the change of power line impedance and the interference of power line noise. In order to increase the communication distance of the power carrier, we must move away from the power switching frequency of the circuit carrier unit. The carrier frequencies currently used in China are 115KHz and 132KHz. In this case, the switching frequency is around 60KHz for the 48V input power supply.