How to choose between single-point and multi-point grounding for a smart controller PAC?

The grounding method for a Power Controller (PAC) must be selected based on the frequency, circuit type, and system structure. For low-frequency (<1MHz) analog circuits and sensitive circuits, single-point grounding is used to avoid ground loops, with all ground wires converging at a single power input point. For high-frequency (>10MHz) digital circuits and distributed systems, multi-point grounding is used to reduce grounding impedance, with each ground plane directly connected to the chassis via multiple vias. In hybrid systems, a hybrid grounding approach can be used: single-point grounding for low-frequency components and multi-point grounding for high-frequency components via capacitors (e.g., 1000pF) to the chassis.

In practice, single-point grounding uses a star topology with short, thick ground wires; multi-point grounding requires a complete ground plane and a low-impedance connection to the chassis (e.g., using metal screws and grounding posts). Test comparisons show that single-point grounding can reduce low-frequency noise of the PAC by 20dB, while multi-point grounding reduces high-frequency (>30MHz) radiated emissions by 15dB. The system must pass the IEC61000-5-2 grounding standard verification.