Datasheet

Table Of Contents

19.6.2.4 Sleep Mode Operation

The Voltage Reference output and the Temperature Sensor output behavior during sleep mode can be

configured using the Run in Standby bit and the On Demand bit in the Voltage Reference register

(VREF.RUNSTDBY, VREF.ONDEMAND), see the following table:

Table 19-1. VREF Sleep Mode Operation

VREF.ONDEMAND VREF.RUNSTDBY Voltage Reference Sleep behavior

- - Disable

0 0 Always run in all sleep modes except standby sleep mode

0 1 Always run in all sleep modes including standby sleep mode

1 0 Only run if requested by the ADC, in all sleep modes except

standby sleep mode

1 1 Only run if requested by the ADC, in all sleep modes including

standby sleep mode

19.6.3 Battery Backup Power Switch

19.6.3.1 Initialization

The Battery Backup Power Switch (BBPS) is disabled at power-up, and the backup domain is supplied by

main power.

19.6.3.2 Automatic Battery Backup Power Switch

The supply of the backup domain can be switched automatically to VBAT supply pin by the Battery

Backup Power Switch when the BOD33 detects that the VDD supply is below the VDD threshold level

(BOD33.LEVEL). It is switched back to VDD supply pin when the BOD33 detects that VDD is above the

VDD threshold level (BOD33.LEVEL).

To enable this feature, the following configuration is required: BOD33.ACTION=BKUP.

19.6.3.3 Sleep Mode Operation

The Battery Backup Power Switch is not stopped in any sleep mode.

19.6.3.3.1 Entering Battery Backup Mode

Entering backup mode can be triggered by either:

• Wait-for-interrupt (WFI) instruction.

• 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.