21
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
Figure 5-3.
Backup Battery
5.4
Active Mode
Active mode is the normal running mode with the core clock running from the fast RC oscillator,
the main crystal oscillator or the PLLA. The power management controller can be used to adapt
the frequency and to disable the peripheral clocks.
5.5
Low-power Modes
The various low-power modes of the SAM4S are described below:
5.5.1
Backup Mode
The purpose of backup mode is to achieve the lowest power consumption possible in a system
which is performing periodic wake-ups to perform tasks but not requiring fast startup time. Total
current consumption is 1 µA typical (VDDIO = 1.8 V to 25°).
The Supply Controller, zero-power power-on reset, RTT, RTC, Backup registers and 32 kHz
oscillator (RC or crystal oscillator selected by software in the Supply Controller) are running. The
regulator and the core supply are off.
Backup mode is based on the Cortex-M4 deep sleep mode with the voltage regulator disabled.
The SAM4S can be awakened from this mode through WUP0-15 pins, the supply monitor (SM),
the RTT or RTC wake-up event.
Backup mode is entered by writing the Supply Controller Control Register (SUPC_CR) with the
VROFF bit at 1 (A key is needed to write the VROFF bit, please refer to Supply Controller SUPC
section of the product datasheet) and with the SLEEPDEEP bit in the Cortex-M4 System Control
Register set to 1. (See the Power management description in The ARM Cortex-M4 Processor
section of the product datasheet).
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.
Summary of Contents for SAM4S Series
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