9.2.1 Power Supplies
The Atmel SAM L21 has several different power supply pins:
- VDDIO powers I/O lines and XOSC. Voltage is 1.62V to 3.63V
- VDDIN powers I/O lines, OSC16M, 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, DAC, PTC and OPAMP. Voltage is 1.62V to 3.63V
- 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 VDDIN and VBAT as supply for the internal output VSWOUT, see the figure in Power Domain Overview.
The same voltage must be applied to both VDDIN and VDDANA. This common voltage is referred to as VDD in the datasheet.
When the Peripheral Touch Controller (PTC) is used, VDDIO must be equal to VDD. When the PTC is not used by the user application, VDDIO may be lower than VDD.
The ground pins, GND, are common to VDDCORE, VDDIO and VDDIN. The ground pin for VDDANA is GNDANA.
For decoupling recommendations for the different power supplies, refer to the schematic checklist.
References: