Power supply questions
#1
I've seen a number of posts about people having issues with booting, and one thing brought up a lot is not using a good power supply.  I ordered one of the Pine power supplies as an add on, but don't have it yet.  In the meantime, I've ordered from one Amazon that was marked as being for Raspberry Pi 3, rated at 5V, 2.5A, by CanaKit.

What I want to know though, is how high of a current rating can be used?  I don't know if higher current rated power supplies are out there, but if so, could I use a 5.0A, or even a 10.0A?  What is the limit?  I've read that plugging in externals like USB stuff could draw more current and cause voltage drops, so I'm wondering if I should be trying to find a higher current power supply if I plan on plugging in stuff.

And if a supply is rated for higher current, does that mean the current is available if necessary, or will it be always cranking out that much?  If the board is only trying to draw 2.1A, will a 5.0A supply only supply the 2.1A?  I don't want to get a supply that risks burning out the board.

Sorry if these are obvious, I'm not great with electrical stuff.  Thanks!
Kickstarter backer #5,864  --  SBC Noob  --  SE Michigan, USA
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#2
Good question. The pine will only draw the current it needs. In theory you could use a 5v 200A supply and be fine.

I should add one caveat, if you do use something with more than 5A keep in mind you should keep in mind that the slightest short is likely going to be quite sparky and dramatic.
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#3
Maximum current does not matter as long as it is enough. Voltage is critical, it will damage the board when using a PSU with more than 5.1V. Also the micro USB cable is a problem. Use a short one (like 30cm) with low AWG (like 20) or power through Euler bus directly.
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#4
It's probably best to buy a single-piece power supply (a wall wart with a cable having a micro USB plug) rated for least 2000mA as the very minimum (more is even better) and trying to avoid anything with generic detachable USB cables. The generic USB cables are simply not designed for more than 500mA and it's easy to end up with a bad cable. The Raspberry Pi 3 power supply is most likely one of the best possible choices.

The PINE64 has a pretty high peak power consumption, and even the CPU alone can draw up to 1600mA from a 5V PSU under really heavy load. And don't forget about the GPU, which can work simultaneously and consume additional power. Also having two USB ports means that the PINE64 should be ready to supply 500mA + 500mA to the connected USB devices too. There isn't anything particularly bad about this. The Raspberry Pi 3 has exactly the same problem and needs a decent power supply too.
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#5
Thanks for all the comments on this. The one I ordered for Pi 3 off Amazon should arrive today. I was trying to use a wall plug that had a USB cord plug into it before, not a single piece power supply, and the board kept shutting off while trying to boot. I wish I had my Pine power supply, but until I get my shipment of add-ons, I'm hoping this one will do the trick.
Kickstarter backer #5,864  --  SBC Noob  --  SE Michigan, USA
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#6
(04-29-2016, 08:35 AM)montero65 Wrote: I was trying to use a wall plug that had a USB cord plug into it before, not a single piece power supply, and the board kept shutting off while trying to boot.

Check the AWG rating of your cable and have a look at the nice table what to expect from 'typical' AWG28 cables: http://goughlui.com/2014/10/01/usb-cable...ging-slow/

BTW: The PSU you ordered can not be considered 'best choice': https://www.loverpi.com/blogs/news/93532...comparison
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#7
That's a good reference, thanks. I didn't know anything about the power supplies honestly, was just looking for one rated at 5V, 2.0-2.5A, and that CanaKit one seemed the best option on Amazon. So maybe not the best I could have done, but seemed to be the best Amazon had. The SBC scene is new to me, and I'm sure I'll learn more as I go. I'm hoping the Pine one is as good as the LoveRPI then. Any idea on how the LoveRPI stands up against the official RPi available that ssvb mentioned?

I didn't think there would be such differences. Would be nice if Pine recommended which PSU to use, but I'm guessing since they are selling one as well, that might be counter-intuitive to do so.
Kickstarter backer #5,864  --  SBC Noob  --  SE Michigan, USA
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#8
(04-29-2016, 09:11 AM)montero65 Wrote: Any idea on how the LoveRPI stands up against the official RPi available that ssvb mentioned?

Nope, but since RPi foundation invented the problem (AFAIK they were the first using this crappy Micro USB connector to power SBCs which has then been copied by other vendors like Pine64) I would suspect their PSU is OK.

Around the RPi a whole 'industry' developed selling PSUs that do not suck that much (just do a web search for 'psu 5.2V' and you will end up automagically at RPi) so all the issues Pine64 users face now are well known and were to be expected.

But unlike Raspberries where the VideoCore GPU checks available voltage and protects the board by displaying warnings and decreasing clockspeeds we currently have nothing like this with Pine64. Please see both links referenced by ssvb here: https://github.com/longsleep/build-pine6.../issues/16
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#9
(04-29-2016, 09:11 AM)montero65 Wrote: That's a good reference, thanks.  I didn't know anything about the power supplies honestly, was just looking for one rated at 5V, 2.0-2.5A, and that CanaKit one seemed the best option on Amazon.  So maybe not the best I could have done, but seemed to be the best Amazon had.  The SBC scene is new to me, and I'm sure I'll learn more as I go.  I'm hoping the Pine one is as good as the LoveRPI then.  Any idea on how the LoveRPI stands up against the official RPi available that ssvb mentioned?

I didn't think there would be such differences.  Would be nice if Pine recommended which PSU to use, but I'm guessing since they are selling one as well, that might be counter-intuitive to do so.

One of the reasons you dont see recommendations is there are so many fakes. That and since the board is geared toward a hardware hacker crowd (even if the marketing was overdone and trying to sell to everyone). they expect you will know how to find the stuff you need. Since I have learned that the Pi's and Pine can be so sensitive to voltage fluctuation I go overboard. I use supplies well over the needed range and then use DC-DC converters to bring it down to what I need. I fyou have to buy the supply its not cheap, but if you use an old laptop supply or printer, or modem, or network device, you can find supplies that are rated at 2A or better and then just use your choice of DC-DC converter for about $5 or less. This again though is a your mileage will vary. I have had some DC-DC converters that are rock solid at 5.0v until you push them over 500ma then they do odd things mostly though they will drop the voltage down to the 4.5-4.8 range . My current favorite has given me no troulbe but I dont have a dummy load like that review to test it.
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#10
(04-29-2016, 09:34 AM)rahlquist Wrote: they expect you will know how to find the stuff you need.

Or they simply didn't get the idea that powering might be a problem (typical 'hardware guy' behaviour: Using a bench PSU and AWG 20 rated short cables thinking 'what could go wrong?!'). And isn't it funny: They use a bench PSU adjusted to 5.1V but recommend 5.0V PSUs (instead of clearly saying 'get any 5.2V PSU made for Raspberry Pi since we made the same mistake as them and rely on Micro USB'): http://wiki.pine64.org/index.php/Main_Page#Power_Usage

And the problem with (Micro) USB is that focusing on the PSU isn't enough since the cable matters. When I started with this SBC stuff I also had no idea but since I started with A20 boards that already received superiour support by the linux-sunxi community back then I was able to read out the actual voltage: http://forum.lemaker.org/forum.php?mod=v...a=page%3D1

Two times the same PSU but in one case using a 'typical' Micro USB cable voltage drops below 4.6V occured with only slight loads (600 mA consumption). A64 is able to exceed 800mA easily, a few USB peripherals need another 300mA and then every 'typical' AWG28 rated USB cable will let the voltage drop below sane tresholds.
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