
19
RP/RF/RS5C62
3. Configuration of Oscillatory Circuit
VDD
VDD
OSCOUT
OSCIN
C
G
32kHz
C
D
RP/RF/RS5C62
R
F
R
D
A
Typical external components:
X'tal : 32.768 kHz
R
1
2
35k
C
G
=5pF to 35pF
C
D
=5pF to 35pF
Standard values of internal elements:
R
F
=12M
R
D
=60k
In the oscillatory circuit, which is driven by a constant voltage of about 2V relative to the VDD pin, either one end
of the oscillatory capacitors C
G
and C
D
must be connected to the VDD pin without exception.
Reference
< Considerations in Installing Components Surrounding Oscillatory Circuit >
< Other Relevant Considerations >
When either one end of the oscillatory capacitors C
G
and C
D
is connected to the VSS pin instead of the VDD
pin, the oscillatory circuit is still operational but subject directly to fluctuations in the voltage of the system
power supply. Under sharp fluctuations between 5V and battery voltage in particular, the oscillatory circuit
may be brought to a temporary stop. Thus, it is not recommendable to connect either one end of the oscilla-
tory capacitors C
G
and C
D
to the VSS pin.
1) Install the oscillatory capacitors C
G
and C
D
in the closest possible proximity to the IC.
2) Avoid laying any signal or power line in the proximity of the oscillatory circuit (particularly in the area
marked with
“
A
” in the above figure).
3) Apply the highest possible insulation resistance between the OSCIN or OSCOUT pin and the printed cir-
cuit board (PCB).
4) Avoid using any long parallel line to wire the OSCIN and OSCOUT pin.
5) Take extreme care not to cause condensation, which leads to various problems such as failure of the crys-
tal oscillators.
1) When applying an external input of clock pulses (32.768kHz) to the OSCIN pin:
DC coupling...........Prohibited due to mismatching input levels.
AC coupling...........Permissible except that unpredictable results may occur upon detection of the stop of
oscillation if any error occurs in such detection due to such factors as noises. Timer operation is prohibit-
ed upon detection of the stop of oscillation.
2) Avoid using the oscillator output of the RP/RF/RS5C62 (from the OSCOUT pin) to drive any other IC for
the purpose of ensuring stable oscillation characteristics.