I just burned my board

[pfeerick]

well , the minnowboard(another sbc,   http://www.adiengineering.com/products/m...rd-turbot/ ) also does not have overvoltage protection. there has been quite a bit of discussion on mailing list about damage due to user having plugged in something other that 5v and some have said that damage generally does not occur unless greater that 7v. like 9v. on the minnowboard the current takes out an IC  NCT3012S TR  which is primary voltage/current distribution and that particular chip is easy to replace thus bring most of the dead boards back. only if pine64 life was as easy. and this is power supply, not battery. so that is why i kinda question that a 7v, or 7.4v battery can cause real bad damage. maybe it can damage significantly at that voltage, it would surprise me. i mean we live in a world where a lot of 3.3v is tolerant of 5v. it would be nice if i was able to discern current flow from looking at a schematic chart, but i can't  

I'll try and break it down then... 

You have main three methods of powering the pine64 (in no particular order):

• From the microUSB. This is convenient, but has the issues of connector resistance, voltage sag in most 'el cheapo USB leads, and a design spec limitation of 1.8A. The USB spec allows the voltage to be as low as 4.4v, and as high as 5.25v. However, with SBC boards like this... anything below around 4.75 at the connector will cause you grief down the track. This input *should* accept up to around 7v depending on what other components are in the path. 
  
• From the battery. The thing to be aware of here is that this is a single cell battery - so 3.7v nominal (average), and it typically cycles between 3.0 when flat and 4.2v when full. If you connect power to the microUSB port, or the euler bus input (which I'm about to cover) the pine64s PMIC will also charge the battery. The thing to be aware of is that even though there is a three terminal connector on the battery - it is only a single cell, whereas a lot of three wire batteries you will come across are two cell (7.4v nominal), which the PMIC is certainly not expecting... It would probably accept up to around 4.4v without any issues (4.35v max + 0.5v tolerance). The reason for the different connector is the PMIC supports thermal battery monitoring, so the pine64 guys have chosen to use it (rightly so... if you consider the recent Samsung issues!)
  

• The other common (and sometimes preferred method of powering depending on your knowledge and intended use for the board) is the euler bus. You can connect approximately 5v (I run at 5.2v) to the two appropriate pins  (actually 4, but they are simply duplicates to share the load) there. This input *should* accept up to around 7v depending on what other components are in the path. You can look at the pinout diagram linked in my sig to see which pins are the DC_IN and GND pins for external power.
  

Now, the disclaimer. If you burn your board, not my problem :-P No, seriously... I haven't read the schematic fully yet, so don't know what other components are in the Euler in / microUSB power path, so don't know if something else will go pop if you choose to run your board at 6v for some reason. One thing to be aware of is with the Pine64+ boards, the input power also powers the USB ports when the jumper is in the DC_IN position, so running the board at a higher voltage than the USB spec will mostly likely kill an attached USB device. 

So, in a nutshell - if 7v had been connected to the euler buss, or the micro USB... I don't think there would have been an issue. But since it was connected to the battery connector, which at best would have been expecting just under 5v... it was not a very happy chip!

[dkryder]

pfeerick, thanks for the info. one thing that i do not understand about the pine64 is that i would think the jumper that selects between DC/BAT would be near the start of the power flow on the board because it would seem to me no power could do much of anything before that jumper or it would void having the jumper at all yet the jumper is just about on the other side of the board from the supposedly 2 main power input start points. have you any thoughts on why that is? another question is the euler power input, if it is used what would be the correct position of the DC/BAT jumper, or does it matter?

[pfeerick]

With respect to 1 & 3 above (so microUSB power and Euler power), having the jumper in the DC_IN position will make it so the microUSB/euler DC_IN pin (as they are connected together) are providing power to the 5v OUT euler pin, and to the USB ports. Otherwise, if you have the jumper in the BAT position, the PMIC will provide regulated power. And if you don't have the jumper connected at all, you will have no power to the USB, or to the 5v output pins

As I alluded to above, the microUSB input and Euler DC_IN are actually joined together, so if you provide power via the euler DC_IN pin, you can actually plug something microUSB into the pine64 and get power out there if you wanted to for some strange reason! Or if you needed to, the DC_IN pin is also a point to measure the supply voltage making it into the board.

pfeerick, thanks for the info. one thing that i do not understand about the pine64 is that i would think the jumper that selects between DC/BAT would be near the start of the power flow on the board because it would seem to me no power could do much of anything before that jumper or it would void having the jumper at all yet the jumper is just about on the other side of the board from the supposedly 2 main power input start points. have you any thoughts on why that is? another question is the euler power input, if it is used what would be the correct position of the DC/BAT jumper, or does it matter?

[MarkHaysHarris777]

Another way of saying what's going on with the 5v|Batt jumper is that the only way for a 3.7 volt lipo BATT to provide 5v for the output pins and for the usb is to generate it ( dc-dc ) with regulated conversion. I leave my BATTs plugged in and I leave the jumper in the Batt setting, so that my 5v outputs are being generated ... when I removed the 5v DCIN from the euler bus the transfer is seamless;  the fan keeps running, the usb keeps running, and the 5v outputs to the LED lab are always on...  I don't allow the BATT to go below 2-30 % and then I plug in the DCIN.