Clock operation
M41T81
The IRQ/FT/OUT/SQW pin is an open drain output which requires a pull-up resistor to V
CC
for proper operation. A 500-10k resistor is recommended in order to control the rise time.
The FT Bit is cleared on power-down.
Figure 10. Crystal accuracy across temperature
Frequency (ppm)
20
0
–20
–40
–60
2
∆F
F
= K x (T – TO)
–80
–100
–120
–140
–160
= –0.036 ppm/°C2 0.006 ppm/°C2
O = 25°C 5°C
K
T
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
Temperature °C
AI07888
Figure 11. Clock calibration
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
AI00594B
16/30