When the battery is charging through this device via USB and the battery fully charges, does the circuitry disable the charging so that we can leave both the USB and battery connected? Thanks in advance.
When connected to USB, the battery will be charged up to 4.2V and then stops charging. When the battery voltage drops to 4.03V, charging will automatically resume and the battery will be charged to 4.2V.
When USB is connected, XIAO is powered from USB. When USB is disconnected, XIAO is automatically powered from the battery.
See schematic for details.
@msfujino Thanks for the information.
A bit off-topic, but something i noticed when my battery is about to die (when only battery powered). The orange user LED starts to blink on and off periodically at around 500 ms. I thought this is strange because my C++ application just turns this LED on when it starts and nothing more.
The C6 consumes about 70 mA of current even when the radio is not in use (it requires more than 200 mA peak current when the radio is in use). And the minimum operating voltage for C6 is 3.0V. The battery voltage drops when the output current is high and recovers when the output current is low.
I imagine that when VDD falls below 3.0V, C6 stops operating, the battery output current decreases, the battery voltage recovers as a result, and C6 restarts, and so on.