Microchip Technology ATmega4809 Xplained Pro User Manual page 23

4.5.1 Operation at Other Voltages
The ATmega4809 Xplained Pro board is operated at 3.3V or 5.0V by default, but it also has the possibility
of running at other voltages from an external supply.
All signals between the EDBG and the ATmega4809 are level-shifted through level shifters compatible
with supply voltages from 1.65V to 5.5V.
To supply an external voltage:
1. Remove the voltage selection jumper from the power select header J105
2. Check that your external voltage is within the specification of on-board and connected peripherals.
3. Supply the external voltage to the center pin (pin 2) of J105 (do not forget ground)
4. Plug in the EDBG USB cable
Info: The ATmega4809 can be powered from 1.8V to 5.5V and the ATECC508A can be
powered from 2.0V to 5.5V
Info: The EDBG checks the voltage at J105 pin 2 when USB power is applied. If the voltage is
between 1.6V to 5.5V, and not larger than the maximum supported voltage of any connected
Xplained Pro extension power is applied to the ATmega4809, Xplained Pro extension headers,
and the ATECC508A. To bypass this voltage check connect the external voltage to J100 pin 4
instead of J105 pin 2. Caution: Applying power directly to J100 pin 4 which is outside the limits
of the board may cause permanent damage.
3.3V and 5.0V is connected directly to the mikroBUS socket on the board. These voltages will
CAUTION
not follow the externally supplied voltage.
Related Links
Hardware User Guide
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2018 Microchip Technology Inc.
ATmega4809 Xplained Pro
User Guide
Hardware User Guide
DS50002716A-page 23