Driving P-channel mosfet.

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Driving P-channel mosfet.

David C Brown
I am planning to use a P mosfet -  type TP0606 -  as a high side switch for
an LED display.  Everything at  5v.  The gate will be driven by a PIC
output.

Do I need a resistor between PIC and gate, and if so what value?
On t'internet I have seen circuits which don't use a resistor, circuits
which use 100E and circuits that use 10K
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 733236
Derbyshire                eMail: [hidden email]
SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*
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Re: Driving P-channel mosfet. [EE]

Byron Jeff
PIC output maxes out at 25ma. You're swinging the line by 5V.
V=IR so R=V/I = 5/0.025 = 200 ohms.

Personally I wouldn't trust using the PIC's internal resistance to limit
the current. The primary purpose of the resistor is to set the speed of the
gate since it functions as a capacitor. So the lower the resistance, the
faster the gate charges/discharges.

So, put something in the ballpark of 200 ohms and everything should be
fine.

BAJ

On Sat, Sep 12, 2020 at 04:59:08PM +0100, David C Brown wrote:

> I am planning to use a P mosfet -  type TP0606 -  as a high side switch for
> an LED display.  Everything at  5v.  The gate will be driven by a PIC
> output.
>
> Do I need a resistor between PIC and gate, and if so what value?
> On t'internet I have seen circuits which don't use a resistor, circuits
> which use 100E and circuits that use 10K
> __________________________________________
> David C Brown
> 43 Bings Road
> Whaley Bridge
> High Peak                           Phone: 01663 733236
> Derbyshire                eMail: [hidden email]
> SK23 7ND          web: www.bings-knowle.co.uk/dcb
> <http://www.jb.man.ac.uk/~dcb>
>
>
>
> *Sent from my etch-a-sketch*
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist

--
Byron A. Jeff
Associate Professor: Department of Computer Science and Information Technology
College of Information and Mathematical Sciences
Clayton State University
http://faculty.clayton.edu/bjeff
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