MC80F0424 Datasheet, PDF (113/135 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

Preliminary
MC80F0424/0432/0448
22. OSCILLATOR CIRCUIT
The MC80F0424/0432/0448 has two oscillation circuits internal-
ly. X_IN and X_OUT are input and output for frequency, and SX_IN
and SX_OUT are input and output for sub frequency, respectively,
inverting amplifier which can be configured for being used as an
on-chip oscillator, as shown in Figure 22-1.
Note: When using the sub clock oscillation, connect a re-
sistor in series with R which is shown as below Figure 22-
1. In order to reduce the power consumption, the sub clock
oscillator employs a low amplification factor circuit. Be-
cause of this, the sub clock oscillator is more sensitive to
noise than the main system clock oscillator.
C1
X_OUT
C2
8MHz
X_IN
V_SS
C1
R
C2
32.768kHz
SX_OUT
SX_IN
V_SS
Recommended
Crystal Oscillator
Ceramic Resonator
C1,C2 = 20pF ± 10pF
C1,C2 = 20pF ± 10pF
Recommend
C1,C2 = 30pF ~ 90pF
R = 5.7kΩ (if necessary)
Crystal or Ceramic Oscillator
Open
X_OUT
External Clock
X_IN
External Oscillator
Figure 22-1 Oscillation Circuit
Oscillation circuit is designed to be used either with a ceramic
resonator or crystal oscillator. Since each crystal and ceramic res-
onator have their own characteristics, the user should consult the
crystal manufacturer for appropriate values of external compo-
nents.
In addition, see Figure 22-2 for the layout of the crystal.
X_OUT
Note: Minimize the wiring length. Do not allow the wiring to
intersect with other signal conductors. Do not allow the wir-
X_IN
ing to come near changing high current. Set the potential of
the grounding position of the oscillator capacitor to that of
VSS. Do not ground it to any ground pattern where high cur-
rent is present. Do not fetch signals from the oscillator.
Figure 22-2 Layout of Oscillator PCB circuit
MAR. 2005 Ver 0.2
109