I'm making USB to UART interface board that compatibles 1.8V ~ 3.6V logic level. And I found CP2102N`s VIO configuration, so I designed board like this:
But it have a problem when nothing connected with 4-pin connector, because of VIO pin is floating.
According CP2102N`s datasheet, VIO pin must higher than 1.71V, but when I product the board, some of them works well, but some of them burns(Especially connecting the target board when "interface board" connected with host PC.)
Is this configuration is OK? or add some protection circuit makes VIO pin tied?
Sorry for my poor English. Thank you.
what power mode you are using?
i think the main issue on your schematic is that you need a voltage divider resistor network for VBUS pin of CP2102N.
keep vio floating may not damage the device. but my understanding is that reset pin may be also within vio domain, i am wondering if the device still could be enumerated success fuly after you apply the vio.
you may need to pull /rst low then release it to make it work.