0
\$\begingroup\$

Title and image describes it all, can you use one mosfet to switch two things with different voltages from one microcontroller pin?

enter image description here

\$\endgroup\$
2
  • 3
    \$\begingroup\$ Consider what would happen when the switch is off. \$\endgroup\$ – Hearth Jun 16 at 1:47
  • \$\begingroup\$ Almost all discrete MOSFETs have a parasitic body diode. You can see it in their schematic symbol. It means they can only block current in one direction, but can conduct current in both directions. \$\endgroup\$ – DKNguyen Jun 16 at 2:25
2
\$\begingroup\$

It depends on what's connected to J5 and J12. Without knowing the details, I would say you'll likely have problems with J5 in this configuration when the FET is OFF.

Think about voltages with the FET off: J5, pin 1 would be +5V and J5, pin 2 would be ~12V (through J12), and you'd have a -7V reverse voltage on the connected J5 device. If the J5 device can tolerate a large reverse voltage, it might work, but not recommended at first glance.

Consider adding another FET controlled by the same GPIO line instead...

\$\endgroup\$
1
  • \$\begingroup\$ Weirdly I had not considered using another Mosfet controlled from the same GPIO... thank you! \$\endgroup\$ – OkBNA Jun 16 at 20:59
-1
\$\begingroup\$

A FET and BJT alike are just single pole , single throw switches.(SPST or 1P1T) to a low V or ground (NPN or Nch) and high for PNP or Pch. They are both inverting logic switches in common emitter or source.

It takes 2 to make a 2P1T or a 1P2T

\$\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.