Some FET reverese polarity protection circuits

[Phorhas]

HI all
I ran into this while doinf some readung over TI's site http://focus.ti.com/lit/an/slva139/slva139.pdf it's a couple of polarity protection circuits, kinda reminding R.G's andvance RPP circuit (though quite differant). enjoy

[R.G.]

No, it's the same circuit. I just used a 1M gate resistor. I found that in Robert Pease' book on analog troubleshooting.

It's worth noting that you should use MOSFETs with built-in gate protection zeners, and that they should be arranged to allow you to pull the gate in the reverse of the normal direction. If your MOSFET doesn't have gate protection, you should put it in there against the time that you touch a battery lead with a static charge on your body.