Actual voltages, amperage
#11
I just measured the 2.5A supply that came with me Pine and it's looking good so far. It seems to have a slightly higher low load/idle voltage of 5.2V which goes down to 5.1V when the system is booted and running Mate Desktop. If I use the Wifi, BT and both USB ports and run all four cores at full load the voltage at the micro-USB socket drops to 4.9V which is ok considering the cable is rather long...
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#12
Hi,
I posted this in other thread but looks like here I ca receive more information.
My pine arrived yesterday and I installed Debian on it. I put USB hub with it own power supply. I did not noticed anything while starting. At 3rd or 4th start (restart) I turned off HUB's power supply and i got situation as shown on attached picture. HUB is working powered from USB port and also it power supply receive power from USB port.
I know it is normal for HUB to work powered from USB port but is it safe to continue to work with both supplies turned on, or should I look for some power protection solution to protect board from burning while second, hub's power supply is on?


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#13
(06-18-2016, 07:34 PM)MarkHaysHarris777 Wrote:
(06-18-2016, 07:32 PM)NexusDude Wrote: The original post is about the USB2 ports and their output.  Wink

The 5v rail is consistent throughout the board.  I have taken measurements all over the board; including the 5v pin on the RPi port. There shouldn't be one speck of difference.

Not really. First there is the input voltage. Next there is the "PS" net, which is capped to nominally 5 volts, even if you apply a higher input voltage (the AXP datasheet states an input voltage of 7 volts as abolute maximum), if the input voltage is lower, PS carries the input voltage (minus ~0.1 volt dropout).

PS supplies the step up converter (either through the BAT jumper, or directly on Rev. B boards). The converter provides 5.2 volts (+- 1%) to the "5V" Euler/PI connector pins and to the USB ports. If the USB ports is loaded with 8 ohm, the 5V pin drops to 5.0 volts, if the load is further increased, the current is limited to 650 mA and thus the voltage on the USB ports drops further, but the 5V pin stays at 5.0 volts.
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#14
(10-15-2016, 02:21 PM)StefanB Wrote:
(06-18-2016, 07:34 PM)MarkHaysHarris777 Wrote:
(06-18-2016, 07:32 PM)NexusDude Wrote: The original post is about the USB2 ports and their output.  Wink

The 5v rail is consistent throughout the board.  I have taken measurements all over the board; including the 5v pin on the RPi port. There shouldn't be one speck of difference.

Not really. First there is the input voltage. Next there is the "PS" net, which is capped to nominally 5 volts, even if you apply a higher input voltage (the AXP datasheet states an input voltage of 7 volts as abolute maximum), if the input voltage is lower, PS carries the input voltage (minus ~0.1 volt dropout).

PS supplies the step up converter (either through the BAT jumper, or directly on Rev. B boards). The converter provides 5.2 volts (+- 1%) to the "5V" Euler/PI connector pins and to the USB ports. If the USB ports is loaded with 8 ohm, the 5V pin drops to 5.0 volts, if the load is further increased, the current is limited to 650 mA and thus the voltage on the USB ports drops further, but the 5V pin stays at 5.0 volts.

First off, the input voltage is not the 5v rail-- it is DCIN. The 5v rail receives power from one of two places (depending on the 5v|batt jumper) and will be consistent across the rail wherever measured.  I keep the 5v|batt jumper in the batt position on my boards; this provides the most stable and cleanest 5v source for usb and other peripherals. I also dual power my boards via batt and euler bus, and I use a pi-filter on the euler DCIN with a relatively shorter cord on the PSU ( 5v @ 2500 ma).
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