1
\$\begingroup\$

I am trying to switch between USB power and a single cell lipo using two mosfets. Would the circuit below be ideal or is there a more efficient/reliable way to do this?

enter image description here

When the USB is connected the mosfet for the battery should turn off and when the battery is connected and the USB is not the mosfet for the battery should turn on.

\$\endgroup\$
  • \$\begingroup\$ Have you looked for similar questions? As there are a few... \$\endgroup\$ – Solar Mike Jun 9 at 17:58
  • \$\begingroup\$ Yes but they seem to use a diode on one of the inputs and I want to avoid the power loss. \$\endgroup\$ – Zac Jun 9 at 18:11
  • \$\begingroup\$ Why do you yhink they use a diode? Btw how much energy is lost over the diode compared to how much you use in total? \$\endgroup\$ – Solar Mike Jun 9 at 18:15
  • \$\begingroup\$ The diode would have a power loss of 0.6W and I would also need to boost the voltage back to 5V because of the voltage drop. \$\endgroup\$ – Zac Jun 9 at 18:23
  • \$\begingroup\$ You have to carefully design circuits like this to prevent both Mosfets from ever being on at the same time. It is ok (for most systems) if they are both off at the same time because the body diodes will conduct in this situation. There are off the shelf parts to perform this exact function reliably (search for ideal diode or hot swap power controllers). \$\endgroup\$ – Dean Franks Jun 10 at 3:05

Your Answer

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

Browse other questions tagged or ask your own question.