configured in the debugger firmware to ensure that the output voltage never exceeds the hardware limits of the
SAME51J20A microcontroller. The voltage limits configured in the on-board debugger on the SAME51J20A Curiosity
Nano are 1.8V–3.6V. The target voltage is set to 3.3V in production and can be changed through MPLAB X IDE. Any
change to the target voltage done in MPLAB X IDE 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 following figure shows the safe operation
area for the regulator, with an input voltage of 5.1V and an ambient temperature of 23°C.
Figure 3-3. Target Regulator Safe Operation Area
3.3.2
External Supply
The SAME51J20A Curiosity Nano can be powered by an external voltage instead of the on-board target regulator.
When the Voltage Off (VOFF) pin is shorted to ground (GND) the on-board debugger firmware disables the target
regulator and it is safe to apply an external voltage to the VTG pin.
WARNING
Applying an external voltage to the VTG pin without shorting the VOFF to GND may cause permanent
damage to the kit.
WARNING
Absolute maximum external voltage is 5.5V for the level shifters on the board. Applying a higher voltage
may cause permanent damage to the kit.
Programming, debugging, and data streaming is still possible while using external power: the debugger and signal
level shifters will be powered from the USB cable. Both regulators, the debugger, and the level shifters are powered
down when the USB cable is removed.
3.4
Disconnecting the On-Board Debugger
The following block diagram shows all the connections between the debugger and the SAME51J20A microcontroller.
The rounded boxes represent connections to the board edge on the SAME51J20A Curiosity Nano. The signal names
are shown in the following figure and printed in silkscreen on the bottom side of the board.
EV76S68A
Curiosity Nano
©
2020 Microchip Technology Inc.
User Guide
DS70005432A-page 8
