Datasheet

19
SAM3S [SUMMARY]
6500ES–ATARM–11-Feb-13
Figure 5-2. Core Externally Supplied
Note: For USB, VDDIO needs to be greater than 3.0V.
For ADC, VDDIN needs to be greater than 2.0V
For DAC, VDDIN needs to be greater than 2.4V.
Figure 5-3 below provides an example of the powering scheme when using a backup battery. Since the PIO state is
preserved when in backup mode, any free PIO line can be used to switch off the external regulator by driving the PIO line
at low level (PIO is input, pull-up enabled after backup reset). External wake-up of the system can be from a push button
or any signal. See Section 5.6 “Wake-up Sources” for further details.
Figure 5-3. Backup Battery
Main Supply
(1.62V-3.6V)
Can be the
same supply
VDDCORE Supply
(1.62V-1.95V)
ADC, DAC, Analog
Comparator Supply
(2.0V-3.6V)
ADC, DAC
Analog Comp.
USB
Transceivers.
VDDIN
Voltage
Regulator
VDDOUT
VDDCORE
VDDIO
VDDPLL
ADC, DAC
Analog Comp.
USB
Transceivers.
VDDIN
Voltage
Regulator
3.3V
LDO
Backup
Battery
-
ON/OFF
IN
OUT
VDDOUT
Main Supply
VDDCORE
ADC, DAC, Analog
Comparator Supply
(2.0V-3.6V)
VDDIO
VDDPLL
PIOx (Output)
WAKEUPx
External wakeup signal
Note: The two diodes provide a “switchover circuit” (for illustration purpose)
between the backup battery and the main supply when the system is put in
backup mode.