B USB Power
Feather FONA is a little special and different with how it manages battery and USB
power. Whereas other Feathers can run direct from 3.3V and thus from USB or
battery...
This is because the cellular module cannot run off of 3.3V, and it has thin but common
spikes of an amp or two when connecting/sending data on the cellular network. We
could have gone with a huge voltage regulator but instead we decided to just power
the FONA module direct from the lipoly battery. If this isn't plugged in, the battery
charger ends up trying to source an amp, which it cant, and the board will reset
So, yeah. Use a battery! It will keep topped up when using USB, and allow the cellular
module to draw current spikes without issue
The above shows the Micro USB jack (left), Lipoly JST jack (top left), as well as the
3.3V regulator and changeover diode (just to the right of the JST jack) and the Lipoly
charging circuitry (to the right of the Reset button). There's also a CHG LED, which will
light up while the battery is charging. This LED might also flicker if the battery is not
connected or when the cellular module is in action
You must have a Lipoly/LiIon battery plugged in at all times for using the Feather
FONA
The JST connector polarity is matched to Adafruit LiPoly batteries. Using wrong
polarity batteries can destroy your Feather
©Adafruit Industries
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