The electromagnetic interference produced by switching power
supply often affects the normal work of electronic products. The correct PCB layout
of switching power supply becomes very important. In many cases, a power supply designed perfectly on paper may not work properly during the initial debugging because of many problems in the PCB layout of the power supply.
Nowadays, electronic products are upgrading rapidly. Product design engineers prefer to choose the AC / DC adapter which is easy to purchase in the market, and directly install multiple sets of DC power supply on the PCB board of the system. Because the electromagnetic interference produced by switching power supply will affect the normal work of its electronic products, the correct PCB layout of power supply becomes very important. According to the experience, the basic points of PCB layout of 8-point switching power supply are summarized.
Here is a brief summary of these eight points.
1. The capacitance of the bypass ceramic capacitor should not be too large, but its parasitic series electric induction should be as small as possible;
2. The parasitic shunt capacitance of the inductor should be as small as possible, and the farther the distance between the pins of the inductor is, the better;
3. Avoid placing any power or signal traces on the formation;
4. The area of high frequency loop should be reduced as much as possible;
5. The path of high frequency current on the stratum should not be destroyed when the via hole is placed;
6. A small common circuit on the system board needs different grounding layers, which are connected with the power ground plane through a single point;
7. The driving circuit loop from the control chip to the upper and lower FET should be as short as possible;
8. Switching power supply power circuit and control signal circuit components need to be connected to the ground plane of Xiaotong, which are generally connected through a single point.