4.5.1 Operation at Other Voltages

The SAM L22 Xplained Pro board is operated at 3.3V by default, but it also has the possibility of running at lower voltages from an external supply. The EDBG is designed to run from a 3.3V supply and won't work on other voltages, therefore all connections from the EDBG and the on board 3.3V regulator to the ATSAML22N18A should be removed.

To completely disconnect the EDBG and the on-board power supply from the ATSAML22N18A do the following:

  • Remove the two jumpers from the on-board 3-pin current measurement headers (J101 and J102), and connect the two center pins (pin 2) together with a wire or an ammeter as shown in Figure 4-7
  • Remove R400, R404, R405, R406, R407, R408, R414, R415, R416, R417, R418, R419, R420, R425, R426, R427, R600, R601
  • Optionally cut J100 to remove power to the on-board current measurement headers (J101 and J102) from the on-board regulator

Figure 4-6 shows all components that have to be removed from the bottom side of the PCB for operation at other voltages. To locate the other components, see the assembly drawing in the section above. When the components are removed, the kit can be supplied with a desired voltage through the pins marked 3.3V (pin four) and GND (pin two) on the Xplained Pro power header. To program and debug the ATSAML22N18A the 2x5 50mil Cortex debug connector has to be used with an external debugger.

Info: Operating the ATSAML22N18A on other voltages than 3.3V requires physical modifications on the kit using a soldering iron and an external debugger for programming the ATSAML22N18A. The on-board current measurement only works at 3.3V. The on-board LED is selected for 3.3V operation, the light level at 1.8V operation is very low. To increase the emitted light level the value of the series resistor can be lowered. The EDBG functionality can be restored by re-soldering the removed components and soldering a 0Ω resistor over J100.
CAUTION: The voltage supplied through the power header is applied directly to the ATSAML22N18A and the extension headers, applying a voltage greater than 3.3V may damage the board permanently.
Figure 4-6. SAM L22 Xplained Pro EDBG Disconnect
Figure 4-7. SAM L22 Xplained Pro Current Measurement Headers