I have driven the 2n7000 directly from the MPU pin running down to 3 volts,
no problems yet.

I want to replace the FET because too many of them die when the MPU is out
of the circuit board.

Bob, what do you mean by "the normal part with a resistor"? Thanks


----- Original Message ----- 
From: "Gordon Williams" <g_will@cyberus.ca>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Thursday, December 14, 2006 7:25 PM
Subject: Re: [EE] Want to replace 2n7000 with bipolar


> I'm looking at a design for a boost supply (from 4 to 6.5 volts at 20mA ).
> I'm interested in the comments on this FET.
>
> What is the best way to drive the 2n7000?  Can this be done from a PIC pin
> or does the capacitance cause too much current surge?
>
> >From the datasheet it appears that the gate- source voltage is usually in
> the 5 to 10 volt range and the Vgs(th) is between 0.8 and 3 volts.  Can
this
> be driven on with a PIC running on 3.3 V?
>
> I'm wondering with the 3.3V drive voltage whether the Rds(on) voltage drop
> will be comparable to a 2N2222 at saturation (or maybe a bit more)?
>
> Would the 2N2222 be easier to implement and just as efficient?
>
> Regards,
>
> Gordon Williams
>
> ----- Original Message -----
> From: "Forrest W. Christian" <forrestc@imach.com>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Thursday, December 14, 2006 6:55 PM
> Subject: Re: [EE] Want to replace 2n7000 with bipolar
>
>
> > John Pearson wrote:
> >
> > >I have been using a 2n7000 FET in an RS232 circuit, but want to go with
a
> bipolar.
> > >
> > >
> > I'll echo what others have said....  Why?
> >
> > I'd switch all of my 2N2222 and 2N390x circuits to a 2n7000 if I
could...
> >
> > -forrest
> > --
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> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
>
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