Help needed with high side switching

Development
1

For the universal programmer plank/shelf I need to switch in some high voltages at will (using an IO pin) and came up with a (I think) bogstandard approach. In the simulations it seems to work, but in reality is that the voltages are always switched on.

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In this case I got the 12.5V on the output (simulated with a 1Meg resistor), but the simulation says it shouldn;t be there.. These are the actually used resistance values. The npn transistor is an 2n2222 (smd) and the fet an si2301 (smd)

link to the simulation on falstad.com: https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgoqoQFMBaMMAKAHNxCqAWPKsLhRR4oUFgDdOPPlJDFConlRTdFUaAhYAnELlXYEKEN167DosPEgsALsdMGjhkY5BGIDFNmilfeAXjccJaqKNBBvsT+CISEGCoI2IzkllQAJnQAZgCGAK4ANjYsAO5CLoQizsYy1qVVvFR61VTWOlUqtMLgJqLYuHAlZd2qVfJidV1jAlRjtSCEMW6LXCIoi3OjChiQqrOD27tbO25B4yAHbvHnx8Iicxe31-rYCvfH3AJPzWcXDUN-cxWSwU7XWg3ap1Br3BXTWIK6fWhpSarjhZiMczRqMWLzugzRJlWiwBgyafwJNXxxJk02+1ky80WaIeOOw4A06kgKG0wN0FV5hIsaHgPIuiK+H1eyCs1kkZJkKPMLWMytVGhY2BcIAAYhB+Pq4CAmCAAEJ0GzZAD0AAttQBRFhAA

Across the 120k is the actually IO pin. simulated as a voltage source here.

Anyone can help me here?

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High side switched make my head swim. If it’s always on then the PFET isn’t being held high enough, so the issue could be in the NPN being always on?

What are the voltages at the FET gate and NPN base?

Can you try an NFET instead of an NPN? With the NPN you need to deal with the 33k/10k base resistor current and I’d suspect that could be an issue.

Are the footprints right for the actual parts you’re using? That would be an obvious one.

3

Meant to add I’d change the NPN base to a few 100 ohms. The bus pirate pins already have a few 100 series resistors. But your problem is always on so I don’t think that is an issue here.

4

Seem to have made a goofup on the footprints. Sorry about that.

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