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Topic: Using Vin and USB at the same time? (Read 1 time) previous topic - next topic

Elbjornbjorn

Hi,

I'm just wondering if it's safe to leave the board powered via Vin when connecting the board to a computer?

I looked at the schematic and the mosfet switch that's used on other boards doesn't seem to be there.

Thanks!

Limba

#1
Jul 17, 2020, 05:15 am Last Edit: Jul 17, 2020, 05:16 am by Limba
U7 is USB power switch + esd prot. Ensure that USB ID pin stays HI state (3v3).
Vin seems to be OK but +5V is directly connected to USB Vbus.
If USB ID is connected to GND then board go to USB-OTG mode so VIN -> PMIC (VPMID) -> U14 usb power switch -> USB Vbus
NX18P3001.pdf (u7, u14)

Elbjornbjorn

Thanks for the info!

So, Vin is protected from reverse currents by D4. As long as Vin + voltage drop across D4 < 5V i should be good.

Limba

About with 2V Vin the EN pin go Hi state (min 1.2V)
I think Vin should be 5V. After reading U7 datasheets it seems VBUSO as input it can't handle over 6V or it's limit when driving USB.

You can check if using only VIN is there anything in +5V pin

Recommend to consult NXP about the chip or contact arduino support for confirmation.

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