2 replies to this topic

[PascalN]

I just bought a Mele Quieter 3C mini fanless computer to use on my AP setup. I have a question about the USB-C power which I hope someone can help me with.

 

The Quieter 3C has 2 USB-C shaped input ports - one is USB-C PD (Power Delivery) and the other is +12VDC only (no USB communications). I have tried both the supplied AC to 12V DC power supply which connects to the +12VDC input (via USB-C type connector) and a USB-C PD charger (for my MacBook Air) connected to the USB-C PD port. Both work fine in their respective sockets.

 

I also tried connecting the PD charger to the +12VDC input. As expected, nothing happens, because that port can't negotiate with the charger to provide power. Fine.

 

However - and here is my question: What if the +12VDC cable is accidentally plugged into the USB-C PD port? Will it go up in flames, destroy the circuit, or do nothing? Does anyone have any insight into this one?

 

Pascal

 

 

[PascalN]

Well, I think I answered my own question. At least as far as my concern about plugging the Mele supplied AC to 12V DC power supply into the wrong USB-C port. As I feared, I did eventually make the mistake of plugging the 12V USB plug into the USB-C data port (not the correct 12V only USB-C style port).

 

I did not think that the supplied power supply implements Power Delivery (PD), and is just a simple 12V DC connected to the USB-C type plug. I was worried that if that plug were to be connected to the USB-C data input that there could be bad results. However, when I did it, nothing happened at all. The Mele Quieter C USB-C data port just did not recognize that there was voltage applied. The light on the power button did not come on. But, nothing at all happened. I removed the mistakenly inserted plug and put it into the correct USB-C 12V only port. The computer was fine, and worked as usual. So, I have convinced myself that my worry was unfounded.

 

I can't speak to other user constructed USB-C style DC cords, but at least the Mele supplied wall wart DC supply doesn't cause any problem.

 

I hope this may be helpful to someone.

 

Pascal

[Dan Finnerty]

It is nice to have confirmation that this is not a problem. I would have been very surprised if it was. I think (but do not know for a fact) that part of the USB-C power distribution spec protects against such problems. Does anyone know how this spec actually works? Will it protect against reversed polarity? What voltage levels will it protect against?