1
\$\begingroup\$

I have a solar panel and an external power source feeding into a DC converter (U10) that are both used to feed a battery charger (U2):

enter image description here

In a previous design I used 2 schottki diodes to prevent back feeding from solar to U10 and from U10 to solar.

But as the schottky has a voltage drop I would like to use a different solution with as little power loss as possible.

Any tip on how to design this?

Thx!

\$\endgroup\$
3
  • \$\begingroup\$ Using an ideal diode. The circuit generates only 20mV voltage drop. \$\endgroup\$
    – Marko Buršič
    Commented Feb 28, 2019 at 11:13
  • \$\begingroup\$ just wondering.... suppose the external power is connected AND solar panel is generating a minumum amount of power and gets to 3 volts, it opens the diode. Will the higher voltage on "OUT" pin of the diode close the ideal diode preventing feedback to the solar panel? \$\endgroup\$
    – Jeroen
    Commented Feb 28, 2019 at 12:07
  • \$\begingroup\$ Ideal diode circuits for example LTC4358 do always apply such voltage on gate, so that there is a minimal yet operational/detectable forward voltage drop. It works as variable resistor, if the voltage tends to be smaller or even negative it forces the MOSFET to reach high resistance and stop conducting. \$\endgroup\$
    – Marko Buršič
    Commented Feb 28, 2019 at 12:37

1 Answer 1

Reset to default
2
\$\begingroup\$

You can use a mosfet to act as a diode like in this article

It is also covered in this post check the answer of Russel which link to this article

Using a MOSFET in place of a diode provides a resistive channel so that voltage drop is proportional to current and can be much lower than for a diode.

The question is also discussed here

enter image description here

\$\endgroup\$
1
  • \$\begingroup\$ thx, as I am using max 500 mA at 5V I think the ideal diode is the best option, thx Marco! \$\endgroup\$
    – Jeroen
    Commented Feb 28, 2019 at 11:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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