USB1_VBUS and USB2_VBUS

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Biff

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Good evening, all.
I'm trying to create a board based on the Teensy 4.1 design, and may have run into a power sequencing issue. My design will only support one USB port, so I have only connected +5V power to the USB1_Vbus pin. USB2_Vbus is floating.

That seems find and dandy, since NXP documents state that unused RT1062 analog pins, including USB stuff, can be left disconnected.

However, Paul connects both USB1_Vbus and USB2_Vbus to VIN or Vusb, and these pins start the critical power-sequencing process. Will my design power-sequence properly if only the USB1_Vbus pin is connected?

I've Gerbered the board already, so it's too late to make what would be a pretty trivial change, thus I'm hoping to get a 'that should be fine' from you guys. :confused:

Many thanks!
Biff
 
Not clear what is seen as the second : USB2_Vbus

Is this on the chip level, or referring to the Primary DEVICE USB connector and the Mid PCB USB Host connection pins?

As far as power from device USB? There is a trace that can be cut that removes VIN from the USB cable - but the internal USB DEVICE is active when otherwise powered by VIN and ready for use when data lines appear on the Device connector.

The USB Host pins can act as USB Host and will use 5V power from the PCB as presented, or if connected to a powered hub simply communicate to the HUB and the hub will power connected devices in use.
 
Will my design power-sequence properly if only the USB1_Vbus pin is connected?

I have not personally tested this way, but from NXP's documentation it probably should work.

As with all freshly designed PCBs, best to build & verify only a few prototypes before committing to production quantities.


Not clear what is seen as the second : USB2_Vbus

It's BGA pin P6.

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Thanks Paul. I'm only building 5 bare boards, so it would not be too disastrous if it turns out a connection to USB2_Vbus is, indeed, required. But it would clearly be better to get it right the first time.
I ignored USB2_Vbus because of this list in the RT1062 datasheet:
floating sigs.jpg

And I found no reference to *required* signals for power sequencing. Fingers are crossed...
 
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