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USB3 burned out

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Posted at 11/30/2017 13:33:01      1#
Last edited by ballsystemlord In 11/30/2017 13:34 Editor

I was looking at the electrical specs a few days ago (See page 6 of Firefly-RK3399_V10_SCH_(2017-2-8).pdf), and they scared me ! The USB ports do not have enough power going to them. The RK3399 is running 2 amps to 6 ports through a single step down buck converter. The USB2.0 ports require 0.5 amps each. 0.5*4 == 2. The USB-C and USB 3.0 ports use 0.9 amp each 0.9*2 == 1.8. 2+1.8 == 3.8 (OVER CURRENT!) And then you have to add in the power requirements of the processor and the MIPI interfaces and the EDP connector and so forth!!!!
I don't know the technical details of the PCBs wiring so I can't tell you how much current it can handle.
Your camera may have been drawing within the USB spec or not. I don't know. If it were overdrawing current then the SY6280 would be overdrawn for power. But in general if you did not change your kernel or anything between the last reboot and this one then you probably have fried something.
This is something which we might be able to correct by rewiring the USB ports power lanes to an external source, but aside from that I have no idea what to do. I'm just not an electrical engineer and I don't suppose that the firefly team can replace all of our products because they draw too much power through one step down buck converter.
I am hoping that they do not make this same mistake in their next product.
The M.2 adapter does not look overdraw, power wise. The same for the fan.
I had hopped to warn people before something like this happened (and figure out how much power we really need to pull through the buck converter), but it looks like I'm too late.
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