R2023K datasheet(29/50 Pages) RICOH

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R2023K/T

Configuration of Oscillation Circuit and Correction of Time Count

Deviations

• Configuration of Oscillation Circuit

32kHz

OSCIN

OSCOUT

Oscillator

Circuit

The oscillation circuit is driven at a constant voltage of approximately 1.2 volts relative to the level of the VSS pin

input.

As such, it is configured to generate an oscillating waveform with a peak-to-peak voltage on the order of

1.1 volts on the positive side of the VSS pin input.

< Considerations in Handling quartz crystal unit >

Generally, quartz crystal units have basic characteristics including an equivalent series resistance (R1) indicating

the ease of their oscillation and a load capacitance (CL) indicating the degree of their center frequency.

Particularly, quartz crystal units intended for use in the R2023K/T are recommended to have a typical R1 value of

50k

Ω and a typical CL value of 6 to 9pF. To confirm these recommended values, contact the manufacturers of

quartz crystal units intended for use in these particular models.

< Considerations in Installing Components around the Oscillation Circuit >

1) Install the quartz crystal unit in the closest possible vicinity to the real-time clock ICs.

2) Avoid laying any signal lines or power lines in the vicinity of the oscillation circuit (particularly in the area

marked "A" in the above figure).

3) Apply the highest possible insulation resistance between the OSCIN and OSCOUT pins and the printed

circuit board.

4) Avoid using any long parallel lines to wire the OSCIN and OSCOUT pins.

5) Take extreme care not to cause condensation, which leads to various problems such as oscillation halt.

< Other Relevant Considerations >

1) We cannot recommend connecting the external input of 32.768-kHz clock pulses to the OSCIN pin.

2) To maintain stable characteristics of the quartz crystal unit, avoid driving any other IC through 32.768-kHz clock

pulses output from the OSCOUT pin.

Typical externally-equipped element

X’tal : 32.768kHz

(R1=50k

Ω typ)

(CL=6pF to 9pF)

Standard values of internal elements

CG,CD 10pF

typ

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