Recommended UVCC for B-series?


#1

Hello,

Currently in the process of making a carrier board for a B-series based device. I see that the official evaluation board from Particle source 3.3V to the modem(pins 2/4/6/8), while for the simple development module design by @rickkas7, 3.8V is used. Seems like 3.8V has been used in all previous designs.

Is 3.3V ok to use or should I go with 3.8V?

Thanks!


#2

The evaluation board supplies around 3.7V to those pins. UVCC is connected to VCC via the jumper J5.

However, VCC is connected to SW on the bq24195 PMIC, which is the higher voltage output.

The 3.3V output from the XC9258A regulator is 3V3, not VCC.

While technically the B402 modem (LTE) will work at 3.3V, for best performance it should be run at 3.6V to 4.2V.


#3

My mistake. I imported the Eagle schematic into Diptrace and somehow it merged the nets. Thank you for the clarification!