Hardware description
Figure 6: Power supply options (front)
Figure 7: Power supply options (back)
The 5 V from the USB is regulated down to 3.3 V through an onboard voltage regulator. The battery and
external power supply are not regulated. The power from the regulator and external supply is routed
through diodes for reverse voltage protection (D1 and D7), where the circuit is supplied from the source
with the highest voltage. The power from the battery is routed through a load switch and a transistor.
These are controlled by the regulator voltage or external voltage, so if any of the two other sources are
present, the battery is disconnected from the circuit.
Note: When USB is not powered, the interface MCU is in dormant state and draws an additional
current of approximately 20 mA to maintain the reset button functionality. This affects current
consumption, but not the nRF52832 current measurements, as described in Measuring current on
page 30.
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