Atmel SAM4S Series, Preliminary Data Sheet

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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
When the user does not use the internal voltage regulator and wants to supply VDDCORE by an
external supply, it is possible to disable the voltage regulator. Note that it is different from the
Backup mode. Depending on the application, disabling the voltage regulator can reduce power
consumption as the voltage regulator input (VDDIN) is shared with the ADC and DAC. This is
done through ONREG bit in SUPC_MR.
17.4.4 Supply Monitor
The Supply Controller embeds a supply monitor which is located in the VDDIO Power Supply
and which monitors VDDIO power supply.
The supply monitor can be used to prevent the processor from falling into an unpredictable state
if the Main power supply drops below a certain level.
The threshold of the supply monitor is programmable. It can be selected from 1.6V to 3.4V. This
threshold is programmed in the SMTH field of the Supply Controller Supply Monitor Mode Regis-
ter (SUPC_SMMR).
The supply monitor can also be enabled during one slow clock period on every one of either 32,
256 or 2048 slow clock periods, according to the choice of the user. This can be configured by
programming the SMSMPL field in SUPC_SMMR.
Enabling the supply monitor for such reduced times allows to divide the typical supply monitor
power consumption respectively by factors of 32, 256 or 2048, if the user does not need a con-
tinuous monitoring of the VDDIO power supply.
A supply monitor detection can either generate a reset of the core power supply or a wake up of
the core power supply. Generating a core reset when a supply monitor detection occurs is
enabled by writing the SMRSTEN bit to 1 in SUPC_SMMR.
Waking up the core power supply when a supply monitor detection occurs can be enabled by
programming the SMEN bit to 1 in the Supply Controller Wake Up Mode Register
(SUPC_WUMR).
The Supply Controller provides two status bits in the Supply Controller Status Register for the
supply monitor which allows to determine whether the last wake up was due to the supply
monitor:
• The SMOS bit provides real time information, which is updated at each measurement cycle
or updated at each Slow Clock cycle, if the measurement is continuous.
• The SMS bit provides saved information and shows a supply monitor detection has occurred
since the last read of SUPC_SR.
The SMS bit can generate an interrupt if the SMIEN bit is set to 1 in the Supply Controller Supply
Monitor Mode Register (SUPC_SMMR).