Automatic Power Switch Ready bit in the Interrupt Flag Status and Clear (INTFLAG.APSWRDY) will be
set at the same time.
Related Links
on page 1147
BOD33 Power Switch
When the Configuration bit field in the Battery Backup Power Switch register (BBPS.CONF) are selecting
the BOD33, BOD33 will function as Battery Backup Power Switch. In this case, when the VDD voltage is
below the BOD33 threshold, the backup domain supply is switched to VBAT.
Main Power Supply OK (PSOK) Pin Enable
The state of the Main Power VDD can be used to switch between supply sources as long as the Battery
Backup Power Switch is not configured as Automatic Power Switch (i.e., BBPS.CONF not set to APWS):
when the Main Power Supply OK Pin Enable bit in the BBPS register is written to '1' (BBPS.PSOKEN),
restoring VDD will form a low-to-high transition on the PSOK pin. This low-to-high transition will switch the
Backup Power Supply back to VDD.
Note:
With BBPS.PSOKEN=0 and BBPS.CONF not configured to APWS, the device can not be
restarted.
Backup Battery Power Switch Status
The Battery Backup Power Switch bit in the Status register (STATUS.BBPS) indicates whether the
backup domain is currently powered by VDD or VBAT.
23.6.3.4. Sleep Mode Operation
The Battery Backup Power Switch is not stopped in any sleep mode.
Entering Battery Backup Mode
Entering backup mode can be triggered by either:
•
Wait-for-interrupt (WFI) instruction.
•
Automatic Power Switch (BBPS.CONF=APWS). When the Automatic Power Switch detects loss of
Main Power, the Backup Domain will be powered by battery and the device will enter the backup
mode.
•
BOD33 detection: When the BOD33 detects loss of Main Power, the Backup Domain will be
powered by battery and the device will enter the backup mode. For this trigger, the following
register configuration is required: BOD33.ACTION=BKUP, BOD33.VMON=VDD, and
BBPS.CONF=BOD33.
Related Links
Leaving Battery Backup Mode
Leaving backup mode can be triggered by either:
•
RTC requests and externally triggered RSTC requests, under one of these conditions:
–
The Backup Domain is supplied by Main Power, and the Battery Backup Power Switch is
not
forced (BBPS.CONF not set to FORCED)
–
The Battery Backup Power Switch
is
forced (BBPS.CONF is FORCED)
The device is kept in battery-powered backup mode until Main Power is restored to supply the
device. Then, the backup domain will be powered by Main Power.
•
Automatic Power Switch. Leaving backup mode will happen when Main Power is restored and the
Battery Backup Power Switch configuration (BBPS.CONF) is set to APWS: When
BBPS.WAKEEN=1, the device will leave backup mode and wake up.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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