R2023K datasheet(33/50 Pages) RICOH

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R2023K/T

• Oscillation Adjustment Circuit

The oscillation adjustment circuit can be used to correct a time count gain or loss with high precision by varying the

number of 1-second clock pulses once per 20 seconds or 60 seconds. When DEV bit in the Oscillation Adjustment

When DEV bit is set

to 1, R2023K/T varies number of 1-second clock pulses once per 60 seconds.

The oscillation adjustment circuit

can be disabled by writing the settings of "*, 0, 0, 0, 0, 0, *" ("*" representing "0" or "1") to the F6, F5, F4, F3, F2, F1,

and F0 bits in the oscillation adjustment circuit.

Conversely, when such oscillation adjustment is to be made, an

appropriate oscillation adjustment value can be calculated by the equation below for writing to the oscillation

adjustment circuit.

(1) When Oscillation Frequency (* 1) Is Higher Than Target Frequency (* 2) (Causing Time Count

Gain)

When DEV=0:

Oscillation adjustment value (*3) = (Oscillation frequency - Target Frequency + 0.1)

Oscillation frequency

× 3.051 × 10-6

≈ (Oscillation Frequency – Target Frequency) × 10 + 1

When DEV=1:

Oscillation adjustment value (*3) = (Oscillation frequency - Target Frequency + 0.0333)

Oscillation frequency

× 1.017 × 10-6

≈ (Oscillation Frequency – Target Frequency) × 30 + 1

* 1) Oscillation frequency:

Frequency of clock pulse output from the 32KOUT pin at normal temperature in the manner described in "

P30

• Measurement of Oscillation Frequency".

* 2) Target frequency:

Desired frequency to be set.

Generally, a 32.768-kHz quartz crystal unit has such temperature

characteristics as to have the highest oscillation frequency at normal temperature.

Consequently, the quartz

crystal unit is recommended to have target frequency settings on the order of 32.768 to 32.76810 kHz

(+3.05ppm relative to 32.768 kHz).

Note that the target frequency differs depending on the environment or

location where the equipment incorporating the RTC is expected to be operated.

* 3) Oscillation adjustment value:

Value that is to be finally written to the F0 to F6 bits in the Oscillation Adjustment Register and is

represented in 7-bit coded decimal notation.

(2) When Oscillation Frequency Is Equal To Target Frequency (Causing Time Count neither Gain

nor Loss)

Oscillation adjustment value = 0, +1, -64, or –63

(3) When Oscillation Frequency Is Lower Than Target Frequency (Causing Time Count Loss)

When DEV=0:

Oscillation adjustment value = (Oscillation frequency - Target Frequency)

Oscillation frequency

× 3.051 × 10-6

≈ (Oscillation Frequency – Target Frequency) × 10

When DEV=1:

Oscillation adjustment value = (Oscillation frequency - Target Frequency)

Oscillation frequency

× 1.017 × 10-6

≈ (Oscillation Frequency – Target Frequency) × 30

R2023K Datasheet(PDF) 33 Page - RICOH electronics devices division

R2023K Datasheet(HTML) 33 Page - RICOH electronics devices division

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