Actual voltages, amperage
#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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Messages In This Thread
Actual voltages, amperage - by NexusDude - 06-17-2016, 03:12 PM
RE: Actual voltages, amperage - by pfeerick - 06-18-2016, 03:47 AM
RE: Actual voltages, amperage - by pfeerick - 06-18-2016, 07:06 PM
RE: Actual voltages, amperage - by g_t_j - 06-19-2016, 03:56 AM
RE: Actual voltages, amperage - by NexusDude - 06-18-2016, 07:32 PM
RE: Actual voltages, amperage - by StefanB - 10-15-2016, 02:21 PM
RE: Actual voltages, amperage - by MarkHaysHarris777 - 10-15-2016, 05:22 PM
RE: Actual voltages, amperage - by pfeerick - 06-18-2016, 09:10 PM
RE: Actual voltages, amperage - by g_t_j - 06-19-2016, 04:45 AM
RE: Actual voltages, amperage - by xalius - 06-19-2016, 06:10 AM
RE: Actual voltages, amperage - by janeku - 06-27-2016, 11:07 PM

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