Neil schreef op 16-Dec-14 7:17 PM:
> Hi all,
>
> I'm designing an H-Bridge to drive a 12V motor from a PIC, and I
> understand most of the basics and math, but not clear on when to use
> P-channel and N-channel FETs vs all 4 N-ch FETS.  I expected I'd use
> PFETs & NFETs, with smaller transistors on the gates of the P-FETs to
> get the gate up to 12V to switch off properly, but I've see examples to
> the contrary (using all N-FETs).  Is there a specific reason?
>
> A pointer to a good H-bridge tutorial would be great.
>
> Thanks.
>

Other things being equal, N-fets are better (lower RDSon) than P-Fets,=20
but they are a PITA to use on the high side, because their gates must be=20
~10V *above* the uper rail to switch on properly. Hence for a simple,=20
low-hassle, (relatively) low-current H-bridge an N/P design is preferred=20
because it is simpler, while for a high-performance design all-N is=20
preferred. Where the break even point lies is of course up to the designer.

Wouter van Ooijen
--=20
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