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Grounding on high current PCB?

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carpenter

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Imagine a simple PCB on high side is connecotr for 100A, in center switching MOSFET Rds On 1mOhm, and on low side PCB again connector for 100A to high current ground in power supply.
On board is too MCU with smal connecor +3,3V and low power grount to power supply.

The question is how to connect or not connect, or how to connect both groud?

I would welcome a reference to an app note in which the ground around the high current is being discussed.
 

It is impossible to answer your question without knowing ANYTHING about your circuit. How do we know if you should connect your grounds together?????
 

Hi,

I agree with barry.
It's not that simple. It depends on a lot of things.
Frequencies, PCB layout, inductive coupling, capacitive coupling, where the voltage drops and where both GNDs connected, where the voltages are referenced to...

The usual steps are:
* first decide the requirements
* then draw the schematic and calculate part values
* decide where on the PCB you want which part of the circuit (connectors, switches, high power part, low noise part, isolation, mounting holes ...)
* then do the part placement
* then do the signal routing

Klaus
 

Well I assume the MCU is either monitoring or controlling the MOSFET and 100A current.

So if you don't add isolation between the MCU and those things then you must connect the ground. Are you asking whether to add isolation?

In terms of performance isolation is almost always better. But it adds cost and takes board area.

As others have said to help further we'd need to know more about the circuit to understand some of the tradeoffs.
 

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