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How to use "P channel" Mosfet with Micro(3.3V)

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Sharagim

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Hi,
I am tying to find an acceptable solution for switching on-off with P channel Mosfet.
The Micro which I am using is XMEGA and 3.3V, and the load device which I would like to switch is 24V.
I found a schematic (Below) and when I prototype it I see it is working but very sensitive. For example When I touch the Gate pin on Mosfet or C,B on NPN I see some blink on output.
Is there any better solution for such a purpose?
 

I see it is working but very sensitive. For example When I touch the Gate pin on Mosfet or C,B on NPN I see some blink on output.
Click to expand...
You should also take care that the circuit isn't protected against hammer blows, flooding or fire...

Seriously speaking, it's exactly as "sensitive" against electrical interferences as others circuits with similar impedance level. It's easy to decrease the circuit impedance at power consumption expense.
 

Your schematic is a negative image with very low contrast (Cadence?). I inverted it so it can be seen better.
 

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  • P-channel.png
    P-channel.png
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Hopefully, you did not build it according to the diagram. (FET connected upside down)
 

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  • pmos.png
    pmos.png
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FvM said:
You should also take care that the circuit isn't protected against hammer blows, flooding or fire...
Click to expand...

Every thread that I looked at I found one of your jokes, how many drinks did you have for Christmas? :)
Keep up the good humour.
 

Hi,

There are one part solutions like ITS4142. With overcurrent protection, short circuit protection, overvoltage protection and thermal shutdown.


Klaus
 
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