How to determine the grounding method for a circuit board built with circuit modules?

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How to determine the grounding method for a circuit board built with circuit modules? [Copy link]

The whole circuit board is powered by a switching power supply. There are various circuit boards with 2.54 pitch pins on the circuit board. So what is considered series/parallel single-point grounding? What is considered multi-point grounding?

chunyang

In the case of a board plug-in, if a single-point grounding is required, the ground of the main board and all sub-boards can be arranged in the same position when designing the PCB, that is, a series connection in a stacked manner, and then the main filter capacitor is arranged nearby on the main board, and the negative pole of the filter capacitor is used as the ground junction point, and the power connector is arranged next to it. The order is power connector-main filter capacitor-ground pin of the plug-in pin-ground loop at other positions on the board. The stacked design generally requires that all boards have the same size, and the number of ground pins of the board-to-board plug-in is as large as possible.

However, this connection is obviously not possible in many cases. For example, multiple daughter boards can only be inserted into the main board one by one, and the size is relatively small, so they cannot be stacked. At this time, we can only try to reduce the impedance of the ground loop as much as possible, and use a multi-layer ground plane when necessary. If it is a mixture of digital hybrid and high-frequency circuits and weak signal circuits, the PCB design will be more complicated, and the ground plane needs to be properly divided or even processed in other ways. It is really difficult to explain it in a few words. Mobile phone PCB belongs to this situation.

For large systems with many boards, multiple functions, and many sensitive circuits, the back-connected motherboard is generally used. The back-connected motherboard only serves as an electrical connection between boards, and the various sub-boards are interconnected through a bus, so that each sub-board can be designed independently without interfering with each other.