RV5C339A_03 Datasheet, PDF (28/46 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC WITH VOLTAGE MONITORING FUNCTION

RV5C339A
2.2 Measurement of Oscillation Frequency
RV5C339A
VDD
OSCIN
32.768kHz
OSCOUT
32KOUT
VSS
Frequency
counter
*1) The RV5C339A is configured to generate 32.768-kHz clock pulses for output from the 32KOUT pin at power-on conditionally on setting the XSTP bit to
1 in the control register 2.
*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 fre-
quency of the oscillation circuit.
*^{3) The 32KOUT output pin should be connected to the VDD pin with a pull-up resistor.}
2.3 Adjustment of Oscillation Frequency
The oscillation frequency of the oscillation circuit can be adjusted by varying procedures depending on the usage of
the RV5C339A 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 ^NO
clock circuit?
YES
Allowable time count precision is on order of oscillation
frequency variations of crystal oscillator *¹ plus
frequency variations of real-time clock? *^2, *³
YES
Use 32-kHz clock circuit without regard
to its frequency precision?
NO
Allowable time count precision is on order of oscillation
frequency variations of crystal oscillator *¹ plus
frequency variations of real-time clock? *^2, *³
YES
NO
YES
NO
To Course (A)
To Course (B)
To Course (C)
To 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 ±50 ppm depending on the degree of their oscillation frequency variations.
*^{2) Basically, the RV5C339A are configured to cause frequency variations on the order of ±5 to ±10ppm at normal temperature.}
*^{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.
28