s-35192a Seiko Instruments Inc., s-35192a Datasheet - Page 23

• Manufacturer Part Number: s-35192a
• Description: 3-wire Real-time Clock
• Manufacturer: Seiko Instruments Inc.

Rev.1.2
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 of a clock pulse output from the 32KO pin.
*3. Target value of average frequency when the clock correction function is used.
*4. Refer to Table 11 .
(a) Calculation example 1
(a) Calculation example 2
(b) Calculation example 3
_00
example 1”.
In case of current oscillation frequency actual measurement value = 32.771 [kHz], target oscillation frequency =
32.768 [kHz], B7 = 0 (Minimum resolution = 3.052 ppm)
Correction value = 128 − Integral value
Convert the correction value “99” to 7-bit binary and obtain “01100011 b”.
Reverse the correction value “01100011 b” and set it to B6 to B0 of the clock correction register.
Thus, set the clock correction register:
(B7, B6, B5, B4, B3, B2, B1, B0) = (1, 1, 0, 0, 0, 1, 1, 0)
In case of current oscillation frequency actual measurement value = 32.765 [kHz], target oscillation frequency =
32.768 [kHz]. B7 = 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, 1, 1, 1, 0, 0, 0)
In case of current oscillation frequency actual measurement value = 32.765 [kHz], target oscillation frequency =
32.768 [kHz], B7 = 1 (Minimum resolution = 1.017 ppm)
Correction value = Integral value
Thus, this calculated value exceeds the correctable range 0 to 62,
B7 = “1” (minimum resolution = 1.017 ppm) indicates the correction is impossible.
Caution The figure range which can be corrected is that the calculated value is from 0 to 64.
Correction value
Correction value = Integral value
Caution The figure range which can be corrected is that the calculated value is from 0 to 62.
= 128 − Integral value (29.99)= 128 − 29 = 99
= Integral value (30.00) + 1 = 30 + 1 = 31
= Integral value (90.03) + 1
*1
= 128 − Integral value




(
(
32765 ×
32765 ×
Seiko Instruments Inc.
(Target oscillation frequency) −
(Current oscillation frequency
(
(
actual measurement value)
32768 −
32768 −


(
32771 ×
)
)
(Current oscillation frequency
actual measurement value
(Current oscillation frequency
(
actual measurement value
)
)
32771 −
(
(
3.052 × 10
1.017 × 10
)
(
(
32765
32765
)
(
3.052 × 10
(
)
)
32768
-6
-6
)
)




)
+ 1
+ 1
− 6
)


×
(Current oscillation frequency
actual measurement value)
3-WIRE REAL-TIME CLOCK
*2
*2
)
)
(Minimum resolution)
−
×
(Target oscillation frequency
(Minimum resolution
S-35192A
*4
+ 1
)
*3
)
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