[DRA829] USB related pin
Part Number: DRA829V
I saw a post about VBUS preferred to be tied to GND instead of 3.3V if not used. Could it be floating, i.e. is there any internal resistance?
For the USB ID pins, the post said that a PU/PD are better if not used, is there any internal resistance if left open?
For the ID pins, if no internal resistance, how about tying to GND instead of PU/PD? We don't have much room for resistors in this area, so looking at options.
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In reply to Kevin Parmenter:
To give more context, our board is always a host device.
For VBUS, we do have an external 5V regulator to drive VBUS onto a TYP-C connector. And we enable that regulator with a J7 GPIO pin.
The J7 ADC is used to monitor the CC lines to decide when to enable the 5V.
So we are not using the J7 VBUS pins and DRVBUS for this function since we have it wired up another way. (not trying to be compliant to any spec, we are only reading/writing a flash drive from the USB2 and USB3 ports on the TYP-C connector.
So that is why we want to terminate the J7 ID and VBUS the best way but not using them.
For USB ID, there is an internal resistance behind that pin. You can connect it directly to ground if you are always using it in Host mode, no problem.
For VBUS, there are a few options that don't require external hardware. What code base are you using?
In reply to Zack Brown:
After discussing this internally, we've determined that the controller does not rely on the VBUS input in fixed host mode. So you can simply leave it floating.
Thanks for the additional information, we went ahead and put a zero ohm pulldown on it just in case but we can depopulate that later.
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