What is the focus of EMS design?

The problem of EMS should focus on PCB design, mainly because:

1. The design of the high-frequency transformer in the circuit of the switching power supply system has a certain suppression effect on the pulse group interference;

2. The leap capacitance between the primary circuit and the secondary circuit of the switching power supply system provides a path for the return of the common mode interference to the primary loop from the primary loop to the secondary circuit, so it also has a certain suppression effect on the pulse cluster interference;

3. The setting of the common mode filter circuit at the output end of the switching power supply system can suppress the pulse group interference to a certain extent;

4. The circuit of the switching power supply system itself has no suppression effect on the pulse group interference, but if the circuit layout of the switching power supply is not good, it will aggravate the invasion of the pulse group interference into the switching power supply. In particular, the essence of pulse group interference is the combination of conduction and radiation interference, even if the input filter is adopted, the component of conducted interference is suppressed, but there is still radiation interference around the transmission line, which can be through the poor layout of the switching power supply (the primary or secondary loop layout distance of the switching power supply is too long, it will form a "large ring antenna"), and then affect the anti-interference performance of the whole equipment.

Therefore, there are 3 points to pay attention to in the design of the PCB:

1. PCB-ground routing

2. PCB-ground loop

3. The location of the grounding point