The Nordic Thingy:53™ has a battery monitoring circuit which allows the battery voltage to be sampled by the nRF5340 System on Chip (SoC) ADC.
Transistors Q7A and Q7B enable battery voltage sensing through a resistive divider (R11 and R15). When not sampling, the transistors can be turned off with the BAT_MEAS_ENABLE (P0.16) signal to prevent current leakage to ground. The circuit is designed to ensure that the voltage range on the BAT_MEAS pin over the battery voltage is within the limits required by the nRF5340 SoC General-Purpose Input/Output (GPIO) and ADC. When sampling, the battery voltage of 2.8–4.2 V is scaled down to 360–540 mV at BAT_MEAS (P0.06).
The following schematic describes the battery voltage monitor.
Figure 1. Battery voltage monitor
