I'm busy with a project to switch 5V (0.5A) using a p-channel mosfet (NDP6020) and it's kind of working although I'm getting a unexpected voltage drop across the D-S of the mosfet.
https://www.onsemi.com/pdf/datasheet/ndp6020p-d.pdfThe mosfet is being driven by a NPN transistor and I'm using a 3.3V atmega88 microcontroller to switch the mosfet on/off
With the output of the Atmega88 at 3.3V this turns on Q2 which puts the voltage of gate of the mosfet low enough to turn it on.
I would expect 4.98V at the drain. I though it might be as there was no load on the drain but have added in a 1k resistor from drain to GND and still seeing 4.63V
Clearly there is some issue with the circuit or my understanding of mosfet is wrong.
I've taken voltage readings and added them to the schematic.
Where am I going wrong?