The target voltage regulator is a MIC5353 variable output LDO. The onboard debugger can adjust the voltage output that is supplied to the kit target section by manipulating the MIC5353's feedback voltage. The hardware implementation is limited to an approximate voltage range from 1.7V to 5.1V. Additional output voltage limits are configured in the debugger firmware to ensure that the output voltage never exceeds the hardware limits of the ATmega4809 microcontroller. The voltage limits configured in the on-board debugger on ATmega4809 Curiosity Nano are 1.8-5.1V.
The target voltage is set to 3.3V in production and can be changed through Atmel Studio. Any change to the target voltage done in Atmel Studio is persistent, even through a power toggle.
The MIC5353 supports a maximum current load of 500 mA. It is an LDO regulator in a small package, placed on a small PCB, and the thermal shutdown condition can be reached at lower loads than 500 mA. The maximum current load depends on the input voltage, set output voltage, and the ambient temperature. The figure below shows the safe operation area for the regulator, with an input voltage of 5.1V and an ambient temperature of 23°C.
