increase usb 500ma to 1000a possible?
(08-29-2016, 06:43 AM)tkaiser Wrote:
(08-18-2016, 09:43 PM)listenfree Wrote: so is there any way to increase usb current from 500ma to higher

Only on the 2 GB variants by setting a jumper you connect the power lines of the USB ports directly with DC-IN so an USB connected disk can draw whatever current it needs as long as you keep in mind that you have to avoid the Micro USB connector to power the board.

So using the Euler connector pins 4 (5V) and 6 (GND), switching from PMIC to DC-IN on the 2GB variant you can reliably use a bus-powered disk. Don't think about powering the board through Micro USB in this mode, the tiny contacts and the high cable resistance nearly all USB cables show will lead to voltage drops at disk spin-up which lead to the PMIC doing an emergency power-off of the whole board.

Sorry, this is wrong. Power to the USB ports is always going through the LPW5210B5F current limiter, i.e. 650mA per Port. The DC5V jumper only bypasses the AXP803 and the step up converter.

If you look at the schematics, there is no DC path from the USBVBUS/USBVBUS1 nets other than through the current limiter. Any 1206 size 0 Ohm resistor which can be found on the schematic is "NC", i.e. not implemented on the real boards.

I have the board powered through micro USB, the idle voltage on the PS net is 4.9 Volt. If the load on the USB port is increased, the current never increases over ~680 mA (measured, there are some tolerances in the current limiter itself and in the resistor divider used to set the current). At this load, the PS voltage drops to 4.8 Volt. Depending on the DC5V/BAT setting, the input voltage of the current limiter is either 4.8 Volt or stays at 5.1 Volt (output voltage of the step up converter).

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RE: increase usb 500ma to 1000a possible? - by StefanB - 10-15-2016, 12:05 PM

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