# What is the oscillation period of ATX power supply?

Last Update Time: 2019-03-22 11:44:31

We often see the words "start-up" when we look at the information about the switching power supply. In the field of switching power supply, the essential meaning of starting vibration is that the switch is already in the "turn-on, turn-off, turn-and-turn" mode. The start of the switch tube is the necessary condition for the switching power supply to work properly.

We can also take a step forward to define the time between the switch being turned off from the start to the bottom-once it is turned on-as "switch off time", which is recorded as toff, so, in an oscillation period of the switch tube, the total length of time experienced should be the ratio of the on-off time of the ton + toff switch to the ton + toff of the entire cycle, known as the "duty cycle" of the switch. The so-called pulse width modulation (PWM),) refers to the active adjustment of the length of ton through the chip with PWM function to adapt to the change of load.

For a specific ATX power supply, the oscillation period of the switch tube is relatively fixed, and it is more likely that it has been determined at the design stage. The number of oscillations in unit time (1s) is the frequency of the switching power supply. The relationship between frequency and oscillation period is reciprocal. The frequency of the excitation source in the main circuit of ATX power supply is usually tens of kilohertz. For the ATX power supply of a single switch, the oscillation frequency of the single switch is the same as the frequency of its exciting oscillation source, and for the ATX power supply of the double switch, which turns on alternately between the two switches, the oscillation frequency of the single switch is the same as that of its excitation source. The oscillation frequency of each-switch tube in the double switch is 1 / 2 of the source frequency of its excitation. The specific level of frequency parameters of ATX power source belongs to the scope that power designers need to consider, and it is of little significance to maintenance personnel.