I am designing an HDMI switch with two inputs and one output. I found a multiplexer that can be used specifically for this purpose (HD3SS215) but it needs a 3.3 V power supply.

Can I use the 5 V power port from the HDMI alongside a simple regulator as a power supply or not? MUX draws at most 3.2 mA so that part isn't a problem. I don't really understand the purpose of that power port so I am not sure if it can be shared.


1 Answer 1


HDMI cables typically source +5V. You could diode 'or' the +5 from each port if you like then add a small cap as dictated and your regulator. Use that 3.3V to power the chip. Do not forget to connect grounds. The reason for the diodes is to prevent any system back feeding another unit especially if its power is off.You could use MOSFETs for the 5V isolation and then use the 'or' output to power your regulator.

  • \$\begingroup\$ Thank you for the answer. This is what I have so far ibb.co/X56Vx61 Is this correct? I don' really understand how to use a MOSFET in this situation. \$\endgroup\$ Commented Mar 20, 2022 at 14:27
  • \$\begingroup\$ You can use "using mosfets for reverse battery protection" in your favorite search engine and find complete explanations along with part suggestions and schematics. \$\endgroup\$
    – Gil
    Commented Mar 21, 2022 at 0:38
  • \$\begingroup\$ Ah, see I was missing the keywords. I get it now thanks. \$\endgroup\$ Commented Mar 21, 2022 at 7:34

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.