Table 20-4. RAM Back-Biasing Mode
STBYCDFG.BBIASxx config
RAM
0x0 No Back Biasing mode
No Back Biasing in Standby mode
0x1 Standby Back Biasing mode
RAM is back-biased if the device is in standby sleep mode
0x2 Standby OFF mode
RAM is OFF if the device is in standby sleep mode
0x3 Always OFF mode
RAM is OFF if its power domain is in retention state
20.6.4.2. Regulator Automatic Low Power Mode
In standby mode, the PM selects either the main or the low power voltage regulator to supply the
VDDCORE.
If a sleepwalking task is working on either asynchronous clocks (generic clocks) or synchronous clock
(APB/AHB clocks), the main voltage regulator is used. This behavior can be changed by writing the
Voltage Regulator Standby Mode bits in the Standby Configuration register (STDBYCFG.VREGSMOD).
Refer to the following table for details.
Table 20-5. Regulator State in Sleep Mode
Sleep
Modes
STDBYCFG.
VREGSMOD
SleepWalking
Regulator state for VDDCORE
Active
-
-
main voltage regulator
Idle
-
-
main voltage regulator
Standby
0x0: AUTO
NO
low power regulator
YES
main voltage regulator
0x1: PERFORMANCE
-
main voltage regulator
0x2: LP
-
low power regulator
Note:
1.
SleepWalking is running on GCLK clock or synchronous clock. This is not related to XOSC32K or
OSCULP32K clocks.
2.
Must only be used when SleepWalking is running on GCLK with 32KHz source.
20.6.4.3. SleepWalking and Performance Level
SleepWalking is the capability for a device to temporarily wake up clocks for a peripheral to perform a
task without waking up the CPU from STANDBY sleep mode. At the end of the sleepwalking task, the
device can either be woken up by an interrupt (from a peripheral involved in SleepWalking) or enter again
into STANDBY sleep mode. In this device, SleepWalking is supported only on GCLK clocks by using the
on-demand clock principle of the clock sources.
In standby mode, when SleepWalking is ongoing, the performance level used to execute the sleepwalking
task is the current configured performance level (used in active mode), and the main voltage regulator
used to execute the sleepwalking task is the selected regulator used in active mode (LDO or Buck
converter).
These are illustrated in the figure below.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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