Switching regulated power supply how to avoid interference
Switching regulated power supply (stabilised voltage supply) is an electronic device that can provide stable AC or DC power to the load, including AC regulated power supply and DC regulated power supply two categories. When the grid voltage or load instantaneous fluctuations, stabilised voltage supply will be 10-30ms response speed to compensate for the voltage amplitude, so that it is stable within ± 2%.
Switching regulated power supply is a relatively new type of power supply. It has the advantages of high efficiency, light weight, step-up and step-down voltage, and high output power. But because the circuit works in the switching state, it is relatively noisy. With the figure below, let's briefly talk about the working principle of a buck switching power supply. As shown in the figure, the circuit consists of a switch K (the actual circuit for the transistor or field effect tube), the continuity diode D, the energy storage inductance L, filter capacitor C and so on. When the switch is closed, the power supply through the switch K, inductor L to the load power supply, and part of the electrical energy stored in the inductor L and capacitor C.
Switching regulator power supply operation switching transistor and current diode (can also be another switching transistor) is always alternately on or off, KQ and KD is not an ideal device, the two state transitions require a certain amount of time, which produces a spike interference. During the state transition, the switch that is on is not fully on, while the switch that is off is not off for a moment, there is a direct path from the power supply to ground, generating a transient current Is. This current is related to the difference between the switching triode's on-time current Imax and its off-time current Icmin, and to the duration of the switch's simultaneous on-time of KQ and KD, and other factors. Due to the influence of the circuit distribution parameters, ringing oscillations appear in the waveform.
The switching regulator power supply works by radiating interference into space. The radiation noise level is inversely proportional to the distance from the radiation source. General away from 5cm away from the wiring can be. If the structure does not allow it, it should be shielded. Power input line around the strong electromagnetic field, in order to reduce the electromagnetic coupling between the input line and the output line, the two must be far away.
