How can the sensitive circuitry of a smart controller (PAC) be kept away from power devices?

In the layout of a smart controller PAC, sensitive circuits (such as ADCs, crystal oscillators, and low-level analog circuits) must be kept away from power devices (such as switching power supplies, motor drivers, and relays) to prevent noise coupling. The layout principle is to place power devices concentrated at the edge of the board or on an independent sub-board, and place sensitive circuits diagonally, with a minimum distance of more than 50mm between them. If space is limited, a grounding shield wall (grounding copper strip with a width of ≥5mm) or a metal partition can be inserted in the middle.

When wiring, sensitive signal lines must not run parallel to power lines, and if they cross, they must cross perpendicularly. At the same time, provide independent power and ground planes for sensitive circuits and isolate them from the main power supply through ferrite beads (such as PBZ1608A-102Z0T). Tests show that increasing the spacing by 30mm can reduce the noise of sensitive circuits by 20dB and increase the effective number of bits (ENOB) of the ADC by 1 bit, meeting the requirements of IEC61000-4-8 power frequency magnetic field immunity test.