If low-side switching will work
Thanks for the extra ideas Cookies. One question though : what does it mean (in the description for the N-channel option) by QuoteIf low-side switching will workWhat would you need to check to ensure that was the case?
@Cookies: very elegant. What do they mean with soft start ? I understand the voltage at the gate will rise slowly, so... the fet opens slowly instead of a single switch turn on ? Why would I want this, is it more pleasurable for my IC ?
...but once you wire up a power source with the correct polarity, you can't plug it in backwards, after all.
I can't really think of a situation where low-side switching wouldn't work.
Quote from: oric_dan on Feb 27, 2013, 08:24 pm...but once you wire up a power source with the correct polarity, you can't plug it in backwards, after all.I truly wish that were the case in my experience too
I'm assuming you're using the Power jack, and not hacking into the Vin header pin,which is 50% gotcha, and 50% blew my Mega board to kingdom come.
Actually, all atmega's are soldered to veroboard and - for the moment - powered by 6 AA batteries. The work is done by students learning electronics. Mistakes will be made - the entire idea is learning to build and debug something - so the board goes through several debugging cycles, meaning connecting and disconnecting the power source many times. Reverse polarity protection has already shown a good choice on several occasions
Has anyone got a pet MOSFET that they use for these lower voltage reverse polarity protection challenges? Reason for asking is when I started to look in the parts I have on hand, my logic level MOSFETs that might be useful for protecting reverse polarity on a 5V system are either more expensive than the rest of the Bill of Materials for the project combined or, as in the case of the 2N7000 N-channel which are under 10c each and I have heaps of...actually appear to have a unreasonably high resistance, therefore a power loss which can be as bad as a diode.
Quote from: Cookies on Feb 27, 2013, 12:52 pmYou don't have to use a P channel MOSFET, see diagram C in attached image.Perhaps I'm looking at this wrong, but shouldn't the Drain and Source be reversed in figure C?
You don't have to use a P channel MOSFET, see diagram C in attached image.