[AFMUG] OT F me

[Chuck McCown via AF]

For the first time ever, I needed a high side solenoid coil driver.  

So reading up on high side drivers, I felt confident.  P channel mosfet etc.
Does not work.  

Come to find out that the source of a P channel mosfet is supposed to be 
connected to the positive supply.

Source = source of electrons  Negative, ground, right?
Drain = drain for electrons right... positive,  does this not reference 
electron flow?

Source must mean hole source for P channel mosfet.  ???

Arrgh   Now gotta kludge circuit boards to test but really will have to 
scrap the lot.  

I thought the schematic looked odd because it put the internal body/free wheel 
in conduction mode when the transistor should be off.
AND I found reference schematics showing it with Drain positive...  I figured 
others have drawn schematics of this exact transistor with Drain positive, 
surely those schematics are not erroneous.  They are published on the interwebs 
for heck sake

Ennybuddy know enough solid state device physics to be able to tell me what 
Source actually means for a P channel mosfet?


Best Regards,
Chuck McCown

McCown Technology Corporation 
8401 N Commerce Dr
Lake Point, Utah 84074
801-250-9503 Office
435-830-4306 Cell
www.mccowntech.com
www.microtrench.pro
www.terabitnetworks.com-- 
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Re: [AFMUG] OT F me

[Cameron Crum]

Found this:

What is the direction of current flow in P channel MOSFET?
[image: Simple MOSFET Switching Circuit – How to turn on / turn off N ...]
Current flows into the drain and out of the source. P-channel MOSFETs turn
on when the gate is a few volts below the source, and the drain-source
voltage is negative. Current flows into the source and out of the drain.

In a P-channel MOSFET, the source is connected to a positive voltage, and
the FET will turn on when the voltage on the gate is below the source
voltage by a certain amount (Vgs < 0).


On Thu, Jul 13, 2023 at 1:58 PM Chuck McCown via AF  wrote:

> For the first time ever, I needed a high side solenoid coil driver.
>
> So reading up on high side drivers, I felt confident.  P channel mosfet
> etc.
> Does not work.
>
> Come to find out that the *source* of a P channel mosfet is supposed to
> be connected to the positive supply.
>
> Source = source of electrons  Negative, ground, right?
> Drain = drain for electrons right... positive,  does this not
> reference electron flow?
>
> Source must mean hole source for P channel mosfet.
> ???
>
> Arrgh   Now gotta kludge circuit boards to test but really will have
> to scrap the lot.
>
> I thought the schematic looked odd because it put the internal body/free
> wheel in conduction mode when the transistor should be off.
> AND I found reference schematics showing it with Drain positive...  I
> figured others have drawn schematics of this exact transistor with Drain
> positive, surely those schematics are not erroneous.  They are published on
> the interwebs for heck sake
>
> Ennybuddy know enough solid state device physics to be able to tell me
> what Source actually means for a P channel mosfet?
>
>
> Best Regards,
> Chuck McCown
>
> McCown Technology Corporation
> 8401 N Commerce Dr
> Lake Point, Utah 84074
> 801-250-9503 Office
> 435-830-4306 Cell
> www.mccowntech.com
> www.microtrench.pro
> www.terabitnetworks.com
> --
> AF mailing list
> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
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