HYUNDAI MicroElectronics
GMS81C2012/GMS81C2020
18. OSCILLATOR CIRCUIT
The GMS81C20xx has two oscillation circuits internally.
respectively, inverting amplifier which can be configured
for being used as an on-chip oscillator, as shown in Figure
18-1.
X
IN and XOUT are input and output for main frequency and
SXIN and SXOUT are input and output for sub frequency,
C1
C1
XOUT
SXOUT
C2
C2
4.19MHz
XIN
SXIN
32.768KHz
VSS
VSS
Recommend
C1,C2 = 100~120pF
Recommend
Crystal Oscillator
Ceramic Resonator
C1,C2 = 20pF
C1,C2 = 30pF
Crystal or Ceramic Oscillator
XOUT
Open
XOUT
REXT
For selection R value,
Refer to AC Characteristics
XIN
XIN
External Clock
External Oscillator
Figure 18-1 Oscillation Circuit
Oscillation circuit is designed to be used either with a ce-
RC Oscillator (mask option)
ramic resonator or crystal oscillator. Since each crystal and
ceramic resonator have their own characteristics, the user
should consult the crystal manufacturer for appropriate
values of external components.
Oscillation circuit is designed to be used either with a ce-
ramic resonator or crystal oscillator. Since each crystal and
ceramic resonator have their own characteristics, the user
should consult the crystal manufacturer for appropriate
values of external components.
XOUT
XIN
In addition, see Figure 18-2 for the layout of the crystal.
Note: Minimize the wiring length. Do not allow the wiring to
intersect with other signal conductors. Do not allow the wir-
ing to come near changing high current. Set the potential of
the grounding position of the oscillator capacitor to that of
SS
Figure 18-2 Layout of Oscillator PCB circuit
V
. Do not ground it to any ground pattern where high cur-
rent is present. Do not fetch signals from the oscillator.
MAR. 2000 Ver 1.00
85
HYNIX [ HYNIX SEMICONDUCTOR ]
