Other Parts Discussed in Thread: TPS62163,
I am currently powering the the SAMC21 in dual power supply mode with the 5V TPS62163 and the 3.3V TPS62162, the 5V IC is working fine, however the 3.3V IC is outputting 3.66V(very stable too), which goes above the tolerance of the SD card on my PCB. I am fairly confident it is not my layout since I have used the TPS62162 on a very similar board(no 5V version) and it worked fine. Also another reason I feel like it is not the layout is that the 5v and 3.3V volt versions of this IC have the exact same recommended layout.
The rest of the board is working completley fine, even the ICs that are meant for 3.3V are still functioning(maximum rating is much higher). Its just that long term I feel like the board is prone to randomly failures if I do not address this, especially with the SD card.
My current theories are that is has something to do with the dual voltage configuration of the MCU, but it is very much indicated in the datasheet that this is an intended feature. Also the impedance between the two power rails while off appears to be in the mega ohms, although I did get a ~50kOhm reading a few times.
Possibly the 5V rail, is messing with the feedback of the 3.3V reg.
Another possibility is that it is a bad IC, and I have extra but this also feels improbable. I thought I would check here and see if I could figure out anything before I replace the IC.
Another detail that may be important is that Vin is a 3S lipo.
Any ideas on what would cause a .36V increase on what should be a fixed output voltage?