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Recently I am designing 2 separate pcb. one of them will be controller with low current signal paths and the other one will have mosfets to control high currents(about 10A). I am thinking of connecting 2 boards with a board to board connector. I need to carry 3 signal paths, ground and 12V to the controller board. I have a regulator on controller board regulates 12V to 3.3V. both has own ground plane.

the question is I am not sure about connecting grounds with a standard male-female headers, on the controller side I have IC's with multiple ground connections. is there any possibility to occur ground loop, ground current? if yes how can I prevent? is there any special connector types or circuits that does the trick?

the power supply will be plugged into the high current side of course and I am talking about something like this:

enter image description here

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If the concern is a ground loop, then the best thing would be to have a single point ground, with ground only on one connector, and parallel contacts/pins. Parallel pins will give the design a low resistance pathway for the large current.

I've used 0.1" headers between boards and they worked good (but with not as much current and I used a single point ground, but had headers in many places on the board). I would also consider through hole and not SMT for the bottom connector as it would have more mechanical strength and avoid damage to pads.

10A is a lot for a header, especially if it's a switching current. Let's say each header has 30mΩ (really depends on what connector you have, but probably is around 10-100mΩ) resistance through each contact. A 10A current would produce a 0.3V common mode voltage on ground if only one pin were used. Common mode voltage noise or offset on ground would be my biggest concern in this design.

Consider also that some manufacturers spec 3A for max current per pin on 0.1" headers.

If 6 pins were paralleled and used for ground, then the total resistance would be 5mΩ and only 50mV from a 10A current. I would probably use even more pins than 6 for 10A.

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  • \$\begingroup\$ At that point, it might be sensible to look for different connectors, though! There's board-to-board connectors designed for higher currents. \$\endgroup\$ – Marcus Müller Oct 15 at 22:42
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    \$\begingroup\$ For sure, 10A is a lot! I really like 0.1" headers, they are cheap and if you need more you parallel. \$\endgroup\$ – Voltage Spike Oct 15 at 22:43
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    \$\begingroup\$ but why should I concern carrying 10A on connector. I just need to carry trigger signal for gates on connector pins. as I said power supply will be plugged to high current board. \$\endgroup\$ – sinany1 Oct 15 at 22:48
  • \$\begingroup\$ @VoltageSpike They actually get pretty expensive pretty fast since they use a lot of metal (and plating material) for their size compared to comparable B2B connectors. Less reliable and harder to plug/unplug too. \$\endgroup\$ – DKNguyen Oct 15 at 22:48
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    \$\begingroup\$ @Marcus Müller No there is no 10A return through connector. sorry if I am not clear enough, it will just couple of milliamps current on connector(for microcontroller and other IC's). I already knew that headers can't handle that much current. just want to know if there are grounding issues because of the ground connection of 2 boards. \$\endgroup\$ – sinany1 Oct 15 at 22:56

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