22.6.5.6 Sampling Mode

The Sampling Mode is a low-power mode where the BOD33 is being repeatedly enabled on a sampling clock’s ticks. The BOD33 will monitor the supply voltage for a short period of time and then go to a low-power disabled state until the next sampling clock tick.

Sampling mode is enabled in Active mode for BOD33 by writing the ACTCFG bit (BOD33.ACTCFG=1). Sampling mode is enabled in Standby mode by writing to the STDBYCFG bit (BOD33.STBYCFG=1). The frequency of the clock ticks (F_clksampling) is controlled by the Prescaler Select bit groups in the BOD33 register (BOD33.PSEL).

F_{c l k s a m p l i n g} = \frac{F_{c l k p r e s c a l e r}}{2^{(PSEL + 1)}}

The prescaler signal (F_clkprescaler) is a 1KHz clock, output by the 32KHz Ultra Low Power Oscillator OSCULP32K.

As the sampling clock is different from the APB clock domain, synchronization among the clocks is necessary. See also 22.6.7 Synchronization.