Datasheet

M41T00S Clock operation
Doc ID 10772 Rev 5 15/28
Figure 10. Crystal accuracy across temperature
Figure 11. Clock calibration
3.2.1 Century bit
Bits D7 and D6 of clock register 02h contain the CENTURY ENABLE bit (CEB) and the
CENTURY bit (CB). Setting CEB to a '1' will cause CB to toggle, either from a '0' to '1' or
from '1' to '0' at the turn of the century (depending upon its initial state). If CEB is set to a '0,'
CB will not toggle.
3.2.2 Oscillator fail detection
If the Oscillator Fail bit (OF) is internally set to '1,' this indicates that the oscillator has either
stopped, or was stopped for some period of time and can be used to judge the validity of the
clock and date data.
AI07888
–160
0 10203040506070
Frequency (ppm)
Temperature
°
C
80–10–20–30–40
–100
–120
–140
–40
–60
–80
20
0
–20
= –0.036 ppm/
°
C
2
± 0.006 ppm/
°
C
2
K
Δ
F
= K x (T – T
O
)
2
F
T
O
= 25
°
C ± 5
°
C
AI00594B
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION