GMS87C4060 Datasheet, PDF (84/102 Pages) Hynix Semiconductor – 8-BIT SINGLE-CHIP MICROCONTROLLERS

GMS81C4040/87C4060
PRELIMINARY
21. OSCILLATOR CIRCUIT
The GMS81C4040/GMS87C4060 has two oscillation cir-
cuits internally. X_IN and X_OUT are input and output for
main frequency and OSC1 and OSC2 are input and output
for OSD(On Screen display) frequency, respectively, of a
inverting amplifier which can be configured for use as an
on-chip oscillator, as shown in Figure 21-1 .
C1
X_OUT
C2
fc (MHz)
X_IN
V_SS
Recommend
fc (MHz) C1 & C2 (pF)
10
30
12
16
5
Crystal Oscillator
C1
OSC2
L1
C2
OSC1
V_SS
Recommend
fc (MHz) C1 & C2 (pF)
8
5
12
20
16
10
20
5
L (uH)
100
15
15
15
For selection L,C value,
you have to tune the
frequency to appropriate
range which is dependent
to your target set.
LC Oscillator
Open
X_OUT
External Clock
X_IN
External Oscillator
Figure 21-1 Oscillation Circuit
Oscillation components have their own characteristics, so
user should consult the component manufacturers for ap-
propriate values of external components.
In addition, see Figure 21-2 for the layout of the crystal.
Note: Minimize the wiring length. Do not allow wiring to in-
tersect with other signal conductors. Do not allow wiring to
X_OUT
come near changing high current. Set the potential of the
X_IN
grounding position of the oscillator capacitor to that of VSS.
Do not ground to any ground pattern where high current is
present. Do not fetch signals from the oscillator.
Figure 21-2 Layout example of Oscillator PCB circuit
80
PRELIMINARY
Nov. 1999 Ver 1.0