2
\$\begingroup\$

It's easy enough to use a P-channel MOSFET for doing positive high-side reverse voltage protection.

However, is it possible to do something similar for reverse protection for a negative voltage?

I've used just Schottky diodes in the past, but I've got a design that has a higher than normal current draw on the negative power rail which is causing hot diodes (which is not ideal, as it'll affect their life span).

\$\endgroup\$
1
  • \$\begingroup\$ I gather that a series fuse, which you probably should have anyway, and a reverse-connected parallel diode to blow the fuse is not enough? If so, then perhaps you should include more application details - at least enough to substantiate the need for series-switching solution that uses mosfets. There may well be other solutions. \$\endgroup\$
    – Kuba hasn't forgotten Monica
    Commented Mar 17, 2022 at 17:40

2 Answers 2

Reset to default
1
\$\begingroup\$

Reverse voltage protection of the negative supply line is very similar to using a P-channel MOSFET in the positive supply line. Replace the P-channel MOSFET with an N-channel MOSFET as follows:

schematic

simulate this circuit – Schematic created using CircuitLab

\$\endgroup\$
0
\$\begingroup\$

It should work with NMOS devices equivalently to using PMOS devices for reverse-polarity protection. Also a quick PSCPICE sim. delivered good results. Hope, I could help! ;-)

enter image description here

enter image description here

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.