In the past ten years, my country has also made great progress in the secondary DC power supply products of exchange and transmission equipment. In order to meet the development trend of layered power supply and sub-board power supply for switching equipment, the switching clock frequency of the PWM working mode DC/DC module power supply independently developed and produced in my country in the late 1980s has reached more than 100 kHz. The more advanced surface mount technology (SMT) abroad makes the module power supply circuit compact in structure and small in distribution parameters. The shell adopts continuous six-sided metal shielding, which has better electromagnetic compatibility. The power-to-volume ratio is 0.21 W/cm, the typical power efficiency of the module with -48 V input and 5 V output is 80%. The output can reach four channels and has a complete protection function. Compared with the foreign module power supply in the Chinese market, the market price is only half of the same foreign module power supply.

Around 2000, due to the application of new technologies such as synchronous rectification, soft switching and active box position and the application of new materials such as aluminum substrate and ceramic substrate circuit board, and the switching clock frequency has been greatly improved (about 500 kHz or more), by This enables the power-to-volume ratio of the module power supply to reach 5~6 W/cm3, the conversion efficiency is generally greater than 80%, the minimum output voltage can reach about 1V, and the output power of a single module (whole brick) can reach 700~1000 W, and can reach Technical requirements for industrial and military grades.

The modular power supply can be used to easily and flexibly form rack power boards of various specifications, and parallel and hot backup work can be realized on the rack. The modular power supply has completely replaced the DC/DC converter made of discrete components, making the exchange The equipment realizes layered power supply, which makes it a reality to further improve the operation reliability.