Hi to all,
I am designing a PCB with a digital circuit based on a STM32F103 MCU with USB,LAN and RS232 ports. The power comes from an external wall type
12V/2.5A switching type regulator. There are 3 grounds in my PCB : a digital ground (GND), a connector frame ground (FGND) which is connected to GND through a 3.9nF/1KV capacitor and the input ground (the common which comes from the external power supply) which is connected to GND through a differential line filter.
The pcb according to local regulations has to be enclosed into a metal box and has to be compatible with all CE regulations accordind EMI and ESDs.
In your opinion where the metal frame should be connected ? to GND, to connector frame ground or at the common power supply ground ?
Thanks in advance,
Angelo
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