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Power Considerations
#1
Hello everyone,

    I've been working with Armbian to improve support for the Tinkerboard, and did some power monitoring and experimenting. 

The TL/DR:  Use *At Minimum* a 5.25 Volt supply with 20 AWG or larger conductors.  The extra .25 volts will help overcome some of the inherent losses in powering through such a terrible connector as a micro USB.  The preferred method, however, would be to filter a 5V power supply with a couple of capacitors and power the board directly through the GPIO.  Otherwise stability is going to be a concern, this will never go away without proper power delivery. 

Full post with data:

https://forum.armbian.com/index.php?/top...ment=32018
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#2
Hi, and thanks for all your work!

I'm starting on my 2nd tinkerboard for a different usecase, BUT... I gifted one with a RaspberryPi touchscreen (on DSI) and a 5.1V 3A micro USB power supply (running audio synths for a midi keyboard on TinkerOS_Debian V1.8). I'm not certain, but I think it's 16 awg wire. I'm not sure I can power it through GPIO since the screen uses those pins. After reading the armbian thread and tkaiser's posts, I'm a little worried... Should I be?
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#3
The earliest stability problem will be the 5V peripherals. The RK808 stands between V_SYS and the processor/SD/wireless, all of which run on 3.3V and under. I have honestly only seen true power concerns when attempting to benchmark the board, no normal use case appears to stress it that much. And, if you look at my numbers, the 5.1V supply should help keep you out of the woods as long as it's 20 AWG or larger (I don't think I've ever seen larger than 18 in a cable, remember that AWG 14 is 15 Amp house wire) The numbers get smaller as the wire gets bigger.

And forgot to mention: The really tiny heat sink on the board will mean the CPU throttles speed long before any real power issues can happen.
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#4
I read the whole thread you linked, and encourage others to do so, there's plenty of great information in there, not just about power. I also saw your recommendation for improving the heat dissipation. I haven't gone quite so far as you (I don't know how to cut a notch in aluminium). I found a heat-sink that I liked the look of...

It's rated at 14.4W dissipation according to the Farnell website: http://uk.farnell.com/fischer-elektronik...dp/1850055

I'm an electronics novice, but I think at 5V, this can dissipate nearly 3A as heat, which should mean the chip can run at full speed without throttling. There's someone in the comments here: http://hackaday.com/2017/02/15/review-th...ker-board/

...claiming that the board pulls 4A while over-clocking. I don't think I'll see anything like that in normal use, and don't intend to overclock anyway.

You can buy the heat-sink from farnell, but I bought from ebay as it worked out cheaper: http://www.ebay.co.uk/itm/FISCHER-ELEKTR...1457825425

...probably other distributors sell the same.

I'm also buying a small brushless fan. Figuring out how to assemble all this into my too-small plastic case is going to be interesting!

UPDATE: I want to show off my handiwork! 

[Image: r4KmPdCG46hC0bLxeJJlYq59q-mEMomc6Hw-ICa2...20-h990-no]

Different angle:
[Image: xTIKI_biPnZ0Y8aE-D2-Zyxw4PoNVCotPQFuMMUI...20-h990-no]

I'm really pleased with how it turned out. The black lump before the USB cable is a common mode choke:
[Image: 32CMC_cover_res01.jpg]

I wired it like the one on the right. I don't think it was necessary, but I guess it can't hurt. 

The power pack has a quick-charge 3.0 output, so is capable of providing sufficient amps. The voltage is exactly 5V but I want to measure again when the pack is running low. 

The heat-sink isn't really attached, just stuck on a blob of thermal paste, and squished down by the plastic case lid. I've pinched the four corner prongs inward, and wedged it into the hole I made in the lid, so it creates some extra downward pressure. The 5V fan connector is jammed diagonally across the 3.3V and ground pins in the middle of the GPIO section. After attaching this, the temperature went from a max of 80°C to a max of about 50°C when being benchmarked, and from about 40°C to 30°C when idle (it's relatively cool in my house even in the summer). Now I'm not getting any thermal throttling!
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