Rx5C348A/B
ꢁ
Measurement of Oscillation Frequency
VDD
OSCIN
32768Hz
OSCOUT
Frequency
Counter
32KOUT
VSS
* 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
YES
Allowable time count precision on order of oscillation
frequency variations of crystal oscillator (*1) plus
Use 32-kHz
Course (A)
Course (B)
Course (C)
NO
NO
clock output?
frequency variations of RTC (*2)?
(*3)
YES
YES
Use 32-kHz clock output without regard
to its frequency precision
NO
YES
NO
Allowable time count precision on order of oscillation
frequency variations of crystal oscillator (*1) plus
Course (D)
frequency variations of RTC (*2)?
(*3)
* 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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RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
