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Micro Crystal
Ultra Small Real-Time Clock Module with I
2
C-Bus Interface
RV-8263-C7
January 2019
23/61
Rev. 1.0
OSCILLATOR STOP FLAG
4.3.
When the oscillator of the RV-8263-C7 is stopped, the Oscillator Stop flag OS is set. The oscillator is considered to
be stopped between power up and stable crystal oscillation (start-up time t
START
). This time can be in a range of
typical 200 ms to maximal 2 s depending on temperature and supply voltage.
The flag remains set until cleared by command (see following Figure). If the flag cannot be cleared, then the
oscillator is not running. This method can be used to monitor the oscillator and to determine if the supply voltage
has reduced to the point where oscillation fails.
OS flag:
V
DD
oscillation
OS flag
OS = 1 and flag cannot be cleared
OS = 1 and flag can be cleared
2
3
t
START
1
power up
V
DDmin
backup
supply
main
supply
1
Oscillation now stable.
2
OS flag cleared by software.
3
OS flag set when oscillator stops.