Power Supplies

The Atmel SAM L22 has several different power supply pins:

VDDIO powers I/O lines and OSC16M, XOSC, the internal regulator for VDDCORE and the Automatic Power Switch. Voltage is 1.62V to 3.63V
VDDANA powers I/O lines and the ADC, AC, LCD, and PTC. Voltage is 1.62V to 3.63V
VLCD has two alternative functions:
- Output of the LCD voltage pump when VLCD is generated internally. Output voltage is 2.5V to 3.5V.
- Supply input for the bias generator when VLCD is provided externally by the application. Input voltage is 2.4 to 3.6V.
VBAT powers the Automatic Power Switch. Voltage is 1.62V to 3.63V
VDDCORE serves as the internal voltage regulator output. It powers the core, memories, peripherals, DFLL48M and FDPLL96M. Voltage is 0.9V to 1.2V typical.
The Automatic Power Switch is a configurable switch that selects between VDDIO and VBAT as supply for the internal output VSWOUT, see the figure in Power Domain Overview.

The same voltage must be applied to both VDDIO and VDDANA. This common voltage is referred to as VDD in the datasheet.

The ground pins, GND, are common to VDDCORE, and VDDIO. The ground pin for VDDANA is GNDANA.

For decoupling recommendations for the different power supplies, refer to the schematic checklist.