3.3V power output higher than GPS Atena IC " BGA725L6E6327FTSA1 " Vcc pin

[williamzoe2002]

Hi, every one, I’m William from Taiwan.
I follow the sorce file to rebuild the notecarrier PCB.
When test it yesterday, GPS can not get any signal.
Then, start to debug try to find something different from design or datasheet.
Here have some question about 3.3V.

By follow up the notecarrier schematic.
Plug in the USB we should have 3.3V by power management IC " TPS63021DSJR ".

But I got more than 3.3V almost 4.2V on pin-3.3V.

Here is racommond circuit of power management IC " TPS63021DSJR ".
looks at the pin-FB, is different than the first picture.
maybe that’s why didn’t get the reference voltage.

tps63021.pdf

then, I check the GPS IC " BGA725L6E6327FTSA1 "
max voltage is 3.6V, but now is 4.2V
https://www.mouser.tw/datasheet/2/196/Infineon_BGA725L6_DataSheet_v02_01_EN-1731109.pdf

what could I do to make those right?
thank you all !!

[RobLauer]

Hi @williamzoe2002 and welcome to the Blues community!

I believe you have stumbled across an issue with an older rev of the Notecarrier-AF that raises the 3V3 to 4.1V. The fix is to cut the big trace on the bottom of the board that’s circled in the picture below. This just disconnects the Feather USB pin from Notecarrier-AF, which means the Feather will get its power from its BAT pin, which comes from the +3V3 net, which means the Feather can still be powered from Notecarrer-AF USB.

Sorry about the issue but I hope this helps!