When you power the board with the Vin, the voltage is given to the USB.
At the Tech Specs it is written 7V. I think that this is for the VIN?
The +5V is directly connected to the USB:
This is the way:
This is possible, because the current can run free through the device:
Please let me know if this is correct.
I measured this VIN voltage at my USB-A plug on the other side of the usb-cable.
USB on a computer usually protect themselves from over voltage or shorted connections. You may not like the results.
I installed a switch in the RED USB wire to disconnect the computer PS when using a Vin or 5V input.
Thank you for your replies. But I damaged a computer already with a similar situation. So I am very carefully in this case.
I ordered a "USB Isolator Modul ADUM3160" already, but it is not arrived. And I think I have another solution.
I removed D3
The DL3 was too bright with high voltage. I removed R27 now. But I will connect DL3 with 220R to 3V8.
I have attached now a battery pack with 9V. It works fine. I measure only 0.8V at the USB.
From data sheet of BQ24195L: It should be possible now to attach 17V "Operating Vin (Max)" or even 22V "Absolute Vin (safety rating) (Max)" without damaging something.
I think D3 is not important. D1 should be enough for ESD... protection.
Is there another function of D3?
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