i.MX6UL (MCIMX6G2CVM05AB) - Allowed voltage on USB Data Pins

[jochenstehle]

Hello, is it allowed to put a 3.3V voltage on the not used USB_OTG1_DN and USB_OTG1_DP. I know it is recommended to float if the USB isnt used, but is it allowed?

The device is a MCIMX6G2CVM05AB

Thank you very much Jochen

[weidong_sun]

Hi Jochen,

>>is it allowed?

Yes, it is.

Max voltage allowed is 3.6V, so 3.3V is no problem. but you can't directly connect 3.3V power to pins, because this will cause pin's current too large. It is better to pull pins up to 3.3V via a 10K resistor.

Have a nice day!

BR,

Weidong

[jochenstehle]

Hi Wigros,

thank you very much for your answer. My problem is we have a application like a base-board and cpu-board.

The USB Data + and - are connected to the board to board connector and from the base-board came 3.3v because there are additional other usecases.

Will this current you spoke about distroy the imx6ul? or is it possible to accept the current for a short time and disable the voltage on pin USB_OTG1_VBUS when software is running to disable the USB part of the device? 

[weidong_sun]

Hi Jochen,

>>Will this current you spoke about distroy the imx6ul?

The max current allowed for a GPIO intput is 17.8mA, we can refer to the value for USB data pin, the current of your USB data pins can't be more than 17.8mA. Otherwise, it is possible to destroy processor.

>>or is it possible to accept the current for a short time

Short time should be no problem, However, we cannot expect that this current will not damage the CPU.

>>disable the voltage on pin USB_OTG1_VBUS when software is running to disable the USB part of the device? 

If there is a GPIO pin for controlling 5V power to supply USB_OTG1_VBUS on your board, you can disable it.

Have a nice day!

BR,

Weidong

[jochenstehle]

Hi Weidong,

>>disable the voltage on pin USB_OTG1_VBUS when software is running to disable the USB part of the device? 

>>If there is a GPIO pin for controlling 5V power to supply USB_OTG1_VBUS on your board, you can disable it.

So am i right that there is no problem if on the Data pins are 3.3V if on the USB_OTGx_VBUS Pins is GND?

[weidong_sun]

Hi Jochen,

>>am i right that there is no problem if on the Data pins are 3.3V.

Yes, I think that short time should be no problem.

>>on the USB_OTGx_VBUS Pins is GND?

The connection can cause no input for internal USB LDO, and no power for usb phy.

Have a nice day!

weidong