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High side P-Channel MOSFET with GPIO Pin with default on
Peabody:
So are you clear now on P-channel mosfets?
Bletru:
--- Quote from: PCB.Wiz on July 19, 2024, 10:03:33 pm ---
--- Quote from: Bletru on July 19, 2024, 08:23:31 pm ---If anybody could take a look and see what's wrong with this circuit.
--- End quote ---
As wired, you are not taking the MOSFET gate to 0V.
You do not need an opto coupler here, you can get the same results with a single SMD package resistor Biased transistor pair NPN+PNP, giving Hi = OFF
--- End quote ---
Concerning the transistor: Yes and No, because mixing up 12V at the collector and 3.3V at the gate needs rather a particular NPN transistor in order to get a usable voltage at the output.
That's why have prefered an optocoppler which has more or less an ON-or-OFF behavior...
PCB.Wiz:
--- Quote from: Bletru on July 20, 2024, 03:48:46 pm ---
--- Quote from: PCB.Wiz on July 19, 2024, 10:03:33 pm ---
--- Quote from: Bletru on July 19, 2024, 08:23:31 pm ---If anybody could take a look and see what's wrong with this circuit.
--- End quote ---
As wired, you are not taking the MOSFET gate to 0V.
You do not need an opto coupler here, you can get the same results with a single SMD package resistor Biased transistor pair NPN+PNP, giving Hi = OFF
--- End quote ---
Concerning the transistor: Yes and No, because mixing up 12V at the collector and 3.3V at the gate needs rather a particular NPN transistor in order to get a usable voltage at the output.
That's why have prefered an optocoppler which has more or less an ON-or-OFF behavior...
--- End quote ---
It’s not a single transistor, it’s a PAIR.
one biased NPN drives a biased PNP.
A single small SMD part.
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