S-35390A Seiko Instruments, S-35390A Datasheet - Page 34

• Manufacturer Part Number: S-35390A
• Description: 2-Wire Real Time Clock
• Manufacturer: Seiko Instruments

34
2-WIRE REAL-TIME CLOCK
S-35390A
2. Measurement of oscillation frequency
When the S-35390A is turned on, the internal power-on detector operates and a signal of 1 Hz is output
from the INT1 pin to select the crystal oscillator and optimize the C
measure the signal with a frequency counter following the circuit configuration shown in Figure 38 . A
signal of 1 Hz may not be output depending on the state in which power is applied, so set the selected
frequency steady interrupt using status register_2 and then set 1 Hz signal output using INT1 register_1 to
generate a normal output. For further details, refer to “ Interrupts ”.
Remark If the error range is ± 1 ppm in relation to 1 Hz, the time is shifted by approximately 2.6
Caution 1. Use a high-accuracy frequency counter (1 ppm order).
Figure 38 Configuration of Oscillation Frequency Measurement Circuit
seconds per month (calculated using the following expression).
2. Since the 1 Hz signal continues to be output, initialization must be executed during
3. Refer to the frequency slow/fast range characteristics for C
normal operation.
10
Open
or
Pull-up
–6
(1 ppm) × 60 seconds × 60 minutes × 24 hours × 30 days = 2.592 seconds
SDA
SCL
INT2
S-35390A
Seiko Instruments Inc.
XOUT
INT1
VDD
VSS
XIN
C
g
Frequency
counter
g
value. Turn the power on and
g
.
Rev.1.2
_00