Oman the switching frequency of the AC-DC switching power supply module?(4)
(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.
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.
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 24V input power supply. Such as power carrier, wireless communication, wireless identification, etc. The 24V 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 24V input power supply.