Hello folks, I'm a bit confused: I designed a circuit following this topic directions, built my circuit on 3 different boards, for only the 1st worked. After investigating, I realised I accidentally used a N-channel mosfet on the working board. The gate is driven by an ATMega. I realised that my t…

[image] od1_fr: But apart from that, how comes a P-channel works on a N-channel circuit? What N channel circuit?

[image] od1_fr: I realised that my try/error way to write my program led me to set the pin HIGH to turn ON the switch and LOW for turning it OFF, as for a P-channel would require. Um, normally no. If the source is connected to Vcc, zero volts will turn on the FET.

[image] anon57585045: What N channel circuit? Oops, I flipped the letters. I will edit the post.

[image] od1_fr: the P-Channel which ended up on the working board is a AO3400 . Again, wrong. 3400 is an N channel FET.

Please don't edit the post. Add a correction in a new post. If you flip an "N" it's still an "N" :slight_smile: If you substituted an N channel for a P channel in the circuit you've shown, it can't possibly work because the gate bias will never become positive.

Ok, I un-edited, hope I didn't add a new mistake :exploding_head: So, to make it simpler, what is working for me is a mosfet markt A09T on the above schematic.

Then it's a P channel MOSFET. Did you have some other question?

[image] anon57585045: Then it's a P channel MOSFET Do you mean the marking is misleading?

I'm telling you an N channel FET can not possibly work in the circuit you showed. Draw your own conclusions, or else provide a lot more details. In addition to the gate bias difference, an N channel FET would keep the load powered all the time, through the substrate diode. If you have doubts about…

[image] anon57585045: an N channel FET would keep the load powered all the time Just measured it, and it is powered all the time :confused: So... Is it really a P channel? As it drives neopixels, which I turn black just before turning its power off, i explains why I didn't notice the mistake. …

P-channel MOSFET high side switch

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anon57585045 July 1, 2022, 4:27pm 2

What N channel circuit?

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P-channel MOSFET high side switch

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