Questions about pin B37 (USB0_VBUS_DET) on TX2

Hi nvidia,

I have two questions about ball B37 (USB0_VBUS_DET) on the TX2.

  1. Is the pin 3.3V tolerable?
  2. Can this pin be left floating and still allow RECOVERY mode flashing?

I have found these two related topics:

(1)
In this thread:
https://forums.developer.nvidia.com/t/usb-vbus-detect-threshold/75993
@Trumany states that the pin Voltage Input High threshold is typically 1.1V to 2.1V which is clearly above 1.8V logic level hence I’m hoping that the pin is indeed 3.3V tolerable:

(2)
In this thread:
https://forums.developer.nvidia.com/t/usb0-vbus-det-necessity/108773
@Trumany states that the USB0_VBUS_DET signal is not required for FORCE_RECOVERY to work - is this 100% certain? -> The reason I ask is that if the pin is not 3.3V capable then I will have to cut the trace to it and leave it floating.

Yours truly
Lasse

Hi, thanks for your finding, there is a misunderstanding here. In fact, there is a level shift (NMOSFET) in module to convert voltage of pin B37 to 1.8V level. The Vgs(th) of it is typical 1.6V and range is 1.1V ~ 2.1V, the max Vgs is +/-20V. So the pin B37 is in fact 20V tolerance and can be connected to ground, or floating in forced recovery mode.

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And it is OK to connect to 3.3V in forced recovery mode.

Thank you Trumany !

You saved the day here.

Will you ask your documentation team to reflect this information in the OEM guide, the datasheet and pin mux excel document.

Thanks
Lasse