Hei, I couldn't really find a question regarding this use-case.
I'm hoping to interface a USB (2.0) charging capability to my design and thus I need to have a communication to a USB capable uC, which in this case is a 2.8V (or generalize under 3.3V) powered nRF52840.
Looking in the Product Specification, VDD can be from 1.7V to 3,6V, but USB DP and DM lines are specced from 3.0 - 3.6V. I'm currently understanding that attaching 5V bus voltage to the '<3.3V nRF's' VBUS pin is OK.
So basically:
- am I good, interfacing USB communication lines to a <3.3V powered nRF ?
- Or do I need some form of level shifting between USB from host and <3.3V powered nRF ?
- Then also I'm planning to implement placeholders for pull-up resistors on the DM and DP signals - depending on which criteria applies in previous questions, how would it be good to pull-up these resistors to? Could DECUSB be used for that or directly to VDD is safe as well ?)
