Josh Koffman <joshybear <at> gmail.com> writes:
<snip>

> http://www.fairchildsemi.com/ds/FQ/FQP13N06L.pdf ) I believe I'm well
<snip>

> > Don't (unnecessarily) drive the gate too hard- it may be a good tradeof=
f to
> > have more switching dissipation and less EMI (keep within the SOA =3D
> > Safe Operating Area) curve though). If your PWM is at 100Hz, you don't
> > need to drive it like a 100kHz PWM. Cheaper too, if you can avoid drive=
rs.
>=20
> In this case the PWM would be to dim the indicator (an LED array of
> some kind, still trying to figure out what). This is just an
> indicator, so I don't think I need to go too nuts on the frequency, it
> won't appear on camera or anything like that. It just has to not be
> too flicker-y for a person looking at it.
>=20

For LED dimming I would suggest F~1kHz.  You might see flicker at 100 Hz
with low duty cycle.=20
Even at 1 kHz with LED load you do not need driver to run MOSFET from PIC.=
=20
I would put 51 Ohm resistor PIC->gate, and 100k resitior gate->ground.  You=
r
load is not inductive, no need to add zenner across the gate either, but it
would not hurt.

> > Unlike BJTs, there is a real cost to having a much higher Vds rating th=
an
> > you need, so don't go nuts on the voltage rating (or cut it too close!)=
..
>=20
> The part referenced above has a max Vds of 60V. If I end up switching
> 5V, it'll be rated for 12 times what it's actually switching. Too far?

For this application, 20V Vds should provide sufficient margin of safety. =
=20

Sergey
http://beaglerobotics.com



--=20
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