We are experiencing random restarts that with the help of Balena engineers has been traced to a chip that controls USB power. This chip.
This is most likely because we are using 3 of these adapters per a device in a montioring mode which according to the specs draws 290mA during full receive mode.
This should be under the port max of 500mA hours but due to the substained nature of our usecase we are most likely:
- Overheating that chip linked above
- Overheating the chipset on the adapter causing it to draw more than 500 amps, and flipping current protection on that chip above
The heat is from the chipset on the adapter. (as best I can tell)
Please let me know if I am mistaken in any of my thoughts above, but here are our proposed solutions that has to be in place by next Tuesday.
- Hiring a 3d designer to expand the area under the lid (see the image below)
- Adding a fan to either a hole I make in the side or a hole in the new lid.
- Buying a bunch of these 6-inch USB extension, then plugging the adapters into those and hot glueing them to the side of the case to just reduce the heat passed back from the case to the fin
- With the expanded case, putting something like this powered usb hub that would draw from the 5v rail exposed on the Giop pins.
- In addition to the fan, add little heat sinks to the back of the USB ports and if we get the right sized thermal pad straight on the chips themselves.
Questions regarding the above.
- Would our 3d cases melt? Has anyone done this before? What should we look out for here?
- Can I power the fan off of the black pins labeled ext (the ones the left side of the fin if the USB ports are facing down)? I found one with 3.3v and one that was a ground. But I can’t find them in the schematics.
- This is a question of if the issue is heat alone or extra amps drawn because of the heat? Other than being really really ugly for production devices is there anything I am missing with this plan?
- This might the best one. Can I power this safely of the 5v GIOP pins? Will this put load on something that wasn’t meant to have load put on it? Will heat become an issue in the power management circuits of the fin?
If anyone has anything at all to add this would be great. This power issue only showed itself after putting a lid on the cases so we know we are close to being able to ship.