S-35390A Seiko Instruments, S-35390A Datasheet - Page 24

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

24
2-WIRE REAL-TIME CLOCK
S-35390A
Clock Adjustment Function
A clock adjustment function is provided to logically perform slow/fast adjustment of the 32 kHz clock and
The clock adjustment register value is calculated by the following expression.
correct a slow/fast clock with high accuracy. Use the clock adjustment register to set this function. When
not using this function, be sure to set it to 00h.
Register value
(1) If current oscillation frequency > target frequency (in case the clock is fast)
Caution The figure range which can be corrected is that the calculated value is from 0 to 64
*1.
*2.
*3. This is the frequency to be adjusted by using the clock adjustment function.
*4.
Register value = 128 − Integral value
Current oscillation frequency actual measurement value = 1.000080 [Hz],
Target oscillation frequency = 1.000000 [Hz],
B7 = 0 (minimum resolution = 3.052 ppm),
Thus, set up (B7,B6,B5,B4,B3,B2,B1,B0) = (0,1,1,0,0,1,1,0) for the clock adjustment register.
Slow/fast adjustment
Minimum resolution
Correction range
The example of calculated value 1
The register value is the value set to the clock adjustment register. Set the binarized value of
this value to the clock adjustment register.
This is the measurement value of the signal that is output to the INT1 pin or INT2 pin when
the 1 Hz clock output setting is:
For the minimum resolution, 3.052 ppm or 1.017 ppm can be set using B7 of the clock
adjustment register. When B7 is 0, 3.052 ppm is set and logical slow/fast adjustment is
performed every 20 seconds. When B7 is 1, 1.017 ppm is set and logical slow/fast adjustment
is performed every 60 seconds.
*1
= 128 − Integral value
32kE = 0, INT1ME = 0, INT1FE = 1, INT1 register_1 is 01h (for the INT1 pin)
INT2ME = 0, INT2FE = 1, INT1 register_2 is 01h (for the INT2 pin)
= 128 − Integral value (26.21) = 128 − 26 = 102
− 195.3 ppm to + 192.2 ppm
Seiko Instruments Inc.
Every 20 seconds
(Current oscillation frequency
(Current oscillation frequency
actual measurement value
actual measurement value
3.052 ppm
B7 = 0
Table 13
(1.000080) × (3.052 × 10
(1.000080) − (1.000000)
− 65.1 ppm to + 64.1 ppm
*2
*2
)
)
Every 60 seconds
−
×
(
1.017 ppm
Target oscillation frequency
(
− 6
Minimum resolution
B7 = 1
)
Rev.1.2
*4
)
*3
_00
)
.