I have a really simple power input network like so:


The SMPS will power analog devices with +12V and the regulator will regulate the rest downstream to power digital circuitry with +5V. Additionally, I have two sense terminals on the board that will take measurements of an attached load. The - terminal is connected to ground with everything else. This throws a wrench in my workflow with respect to reverse polarity protection at the sense terminals. If I hook up something in-between 5 and 12 volts or maybe higher on the negative side, I'm afraid my current setup wouldn't be enough and it could damage chips. Should I consider placing a barrier diode on the OUT side of the regulator as well? What are your layout recommendations in regards to protecting against a positive voltage scenario on the - sense terminal?

Thanks in advance.

Edit: I've added more of the schematic for clarity.

enter image description here

  • \$\begingroup\$ Does your sense (-) HAVE to be connected to circuit gnd? \$\endgroup\$ – Kyle B Aug 19 at 2:23
  • \$\begingroup\$ @KyleB In my setup the analog components use that ground as a reference for sensing and feedback loops. Is there another way to do it? I'd love to get some input. \$\endgroup\$ – jm567 Aug 20 at 20:26
  • \$\begingroup\$ Theres always another way ;) Whats the nature of your sensing circuit? Is it just an ADC and you're going straight to the inputs? Or do you have some signal conditioning circuit first???? \$\endgroup\$ – Kyle B Aug 21 at 1:45
  • \$\begingroup\$ @KyleB Yes I am sensing the + side of the shunt resistor with a 16-bit ADC referenced to the same ground potential. Nothing fancy. I prototyped it with a smaller pcb and it gave me accurate current readings for 1 amp +/- 5%. This setup, however, will go up to 5 amps and will use 4 MOSFETS. Let me know what your thoughts are. \$\endgroup\$ – jm567 Aug 21 at 2:53
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    \$\begingroup\$ You might also consider something really simple, like this: components101.com/articles/… \$\endgroup\$ – Kyle B Aug 25 at 17:46

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