-1
\$\begingroup\$

My question is simple - maybe silly. I've got 2 circuits:

  1. MCU with DAC, ADC and another 3.3V electronics enter image description here
  2. Dummy load (Max 24VDC). enter image description here

Do I need to connect two separate grounds (MCU ground and dummy load ground) into common ground?

I think yes, still not certain about it - i don't know the impact on the accuracy of the measurements taken by ADC.

If no, where should I ground the R's and D's - to the MCU ground or dummy load ground? If you have any remarks on this circuit feel free to criticise me.

\$\endgroup\$
  • \$\begingroup\$ What is the purpose of R and Zener in your circuit? \$\endgroup\$ – Unknown123 May 13 at 22:12
  • \$\begingroup\$ When the voltage exceeds the maximum limit eg. 24V the zener makes the short circuit to GND. R's are here because of the voltage divider - 24V could harm 3.3V logic. \$\endgroup\$ – gunnersson May 13 at 22:14
1
\$\begingroup\$

Yes the grounds should be connected together, otherwise you don't know what your Vgs on the MOSFET is. You have a bigger problem, however, because your power resistor is on the wrong side of your MOSFET. You should be doing low-side switching, otherwise you will not be getting your gate voltage high enough over your source voltage.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.