RX5C348A Datasheet, PDF (28/45 Pages) RICOH electronics devices division – 4-WIRE SERIAL INTERFACE

Rx5C348A/B
Measurement of Oscillation Frequency
VDD
OSCIN
OSCOUT
32KOUT
VSS
32768Hz
Frequency
Counter
* 1) The Rx5C348A/B is configured to generate 32.768-kHz clock pulses for output from the 32KOUT pin.
* 2) A frequency counter with 6 (more preferably 7) or more digits on the order of 1ppm is recommended
for use in the measurement of the oscillation frequency of the oscillation circuit.
Adjustment of Oscillation frequency
The oscillation frequency of the oscillation circuit can be adjusted by varying procedures depending on the usage
of Model Rx5C348A/B in the system into which they are to be built and on the allowable degree of time count
errors. The flow chart below serves as a guide to selecting an optimum oscillation frequency adjustment
procedure for the relevant system.
Start
Use 32-kHz
clock output?
YES
NO ^{Allowable time count precision on order of oscillation YES}
frequency variations of crystal oscillator (*1) plus _NO
frequency variations of RTC (*2)? (*3)
YES
Use 32-kHz clock output without regard
to its frequency precision
NO
Allowable time count precision on order of oscillation ^YES
frequency variations of crystal oscillator (*1) plus NO
frequency variations of RTC (*2)? (*3)
Course (A)
Course (B)
Course (C)
Course (D)
* 1) Generally, crystal oscillators for commercial use are classified in terms of their center frequency
depending on their load capacitance (CL) and further divided into ranks on the order of ±10, ±20, and
±50ppm depending on the degree of their oscillation frequency variations.
* 2) Basically, Model Rx5C348A/B is configured to cause frequency variations on the order of ±5 to
±10ppm at 25°C.
* 3) Time count precision as referred to in the above flow chart is applicable to normal temperature and
actually affected by the temperature characteristics and other properties of crystal oscillators.
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Rev.2.01
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