I.MX6DL USB_OTG_VBUS ALWAY OUTPUT 4.4V

[zhongweihe]

My new project used MCU is I.MX6DL , it has tow USB ports ,one port use as a host ,and one port use as a device . now my question is why the  USB device port alway has 4.4V output from USB_OTG_VBUS?

[zhongweihe]

Hello Igorpadykov:

      The first ,thanks your good support ,but I still can't understand why the 3P0 VBUS_sel registor set to 1 and the USB_OTG_VBUS  output 4.4V from MCU itself. but if VBUS_sel set to 0 ,the USB_OTG_VBUS is 0.38V ,could you please help explain what is difference between VBUS_sel registor set to 0 and 1?

[igorpadykov]

Hi zhongwei

in i.MX6DL this is input, so probably it is connected somewhere

on board to 4.4V, other reason is that chip may be damaged.

Best regards
igor
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[zhongweihe]

Hello Igorpadykov:

      After we analysised ,we fond that if 3p0 registor  bit7(VBUS_SEL) was set 0, measured the voltage of USB_OTG_VBUS is about 0.38V. i don't know why? could you please help explain it .thanks so much.

[igorpadykov]

please look at Figure 50-1. Power system overview

i.MX6DQ Reference Manual
https://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf

Best regards
igor