R2025S Datasheet, PDF (17/47 Pages) RICOH electronics devices division – High precision I2C-Bus Real-Time Clock Module

R2025S/D
the Second Counter is incremented once per 32768 32.768-kHz clock pulses generated by the crystal
oscillator. Writing to the F6 to F0 bits activates the oscillation adjustment circuit.
* The Oscillation Adjustment Circuit will not operate with the same timing (00, 20, or 40 seconds)
as the timing of writing to the Oscillation Adjustment Register.
* The F6 bit setting of 0 causes an increment of time counts by ((F5, F4, F3, F2, F1, F0) - 1) x 2.
The F6 bit setting of 1 causes a decrement of time counts by ((/F5, /F4, /F3, /F2, /F1, /F0) + 1) x 2.
The settings of "*, 0, 0, 0, 0, 0, *" ("*" representing either "0" or "1") in the F6, F5, F4, F3, F2, F1, and F0 bits
cause neither an increment nor decrement of time counts.
Example:
When the second digits read 00, 20, or 40, the settings of "0, 0, 0, 0, 1, 1, 1" in the F6, F5, F4, F3, F2, F1, and
F0 bits cause an increment of the current time counts of 32768 by (7 - 1) x 2 to 32780 (a current time count
loss). When the second digits read 00, 20, or 40, the settings of "0, 0, 0, 0, 0, 0, 1" in the F6, F5, F4, F3, F2,
F1, and F0 bits cause neither an increment nor a decrement of the current time counts of 32768.
When the second digits read 00, 20, or 40, the settings of "1, 1, 1, 1, 1, 1, 0" in the F6, F5, F4, F3, F2, F1, and
F0 bits cause a decrement of the current time counts of 32768 by (- 2) x 2 to 32764 (a current time count
gain).
An increase of two clock pulses once per 20 seconds causes a time count loss of approximately 3 ppm (2 /
(32768 x 20 = 3.051 ppm). Conversely, a decrease of two clock pulses once per 20 seconds causes a time
count gain of 3 ppm. Consequently, deviations in time counts can be corrected with a precision of ±1.5 ppm.
Note that the oscillation adjustment circuit is configured to correct deviations in time counts and not the
oscillation frequency of the 32.768-kHz clock pulses. For further details, see "P28 Configuration of
Oscillation Circuit and Correction of Time Count Deviations • Oscillation Adjustment Circuit".
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