S-35399A03-J8T2G Seiko Instruments, S-35399A03-J8T2G Datasheet - Page 28

• Manufacturer Part Number: S-35399A03-J8T2G
• Description: Real Time Clock 2-wire Real Time Clock
• Manufacturer: Seiko Instruments

Specifications of S-35399A03-J8T2G

• Supply Voltage (max): 3 V
• Supply Voltage (min): 1.3 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial
• Supply Current: 0.34 uA
• Package / Case: SOP-8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

28
2-WIRE REAL-TIME CLOCK
S-35399A03
1. How to calculate
(1) If current oscillation frequency > target frequency (in case the clock is fast)
(2) If current oscillation frequency < target frequency (in case the clock is slow)
*1. Convert this value to be set in the clock correction register. For how to convert, refer to “ (a) Calculation
*2. Measurement value when 1 Hz clock pulse is output from the
*3. Target value of average frequency when the clock correction function is used.
*4. Refer to Table 14 .
(a) Calculation example 1
(a) Calculation example 2
(b) Calculation example 3
example 1”.
In case of current oscillation frequency actual measurement value = 1.000070 [Hz], target oscillation frequency =
1.000000 [Hz], B0 = 0 (Minimum resolution = 3.052 ppm)
Correction value = 128 − Integral value
Convert the correction value “106” to 7-bit binary and obtain “1101010b”.
Reverse the correction value “1101010b” and set it to B7 to B1 of the clock correction register.
Thus, set the clock correction register:
(B7, B6, B5, B4, B3, B2, B1, B0) = (0, 1, 0, 1, 0, 1, 1, 0)
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], target oscillation frequency =
1.000000 [Hz]. B0 = 0 (Minimum resolution = 3.052 ppm)
Correction value = Integral value
Thus, set the clock correction register:
(B7, B6, B5, B4, B3, B2, B1, B0) = (1, 1, 0, 1, 1, 0, 0, 0)
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], target oscillation frequency =
1.000000 [Hz], B0 = 1 (Minimum resolution = 1.017 ppm)
Correction value = Integral value
This calculated value exceeds the correctable range 0 to 62.
B0 = “1” (minimum resolution = 1.017 ppm) indicates the correction is impossible.
Correction value
Caution The figure range which can be corrected is that the calculated value is from 0 to 64.
Caution The figure range which can be corrected is that the calculated value is from 0 to 62.
Correction value = Integral value
= 128 − Integral value (22.93) = 128 − 22 = 106
= Integral value (26.21) + 1 = 26 + 1 = 27
= Integral value (78.66) + 1
*1
= 128 − Integral value
⎛
⎝
⎛
⎝
(
(
0.999920 ×
0.999920 ×
(
(
Seiko Instruments Inc.
(Target oscillation frequency) −
(Current oscillation frequency
1.000000 −
1.000000 −
actual measurement value)
⎛
⎝
(
1.000070 ×
(
1.000070 −
(Current oscillation frequency
actual measurement value
(Current oscillation frequency
actual measurement value
)
)
)
)
(
(
3.052 × 10
1.017 × 10
(
(
)
0.999920
0.999920
)
(
3.052 × 10
(
1.000000
INT /
)
-6
)
-6
)
)
1
⎞
⎠
⎞
⎠
+ 1
+ 1
INT
− 6
)
×
(Current oscillation frequency
)
actual measurement value)
*2
2
*2
⎞
⎠
)
)
(Minimum resolution)
pin.
−
×
(Target oscillation frequency
(Minimum resolution
Rev.2.0
*4
+ 1
)
*3
_00
)