Figure 19-3 Crystal Resonator Equivalent Circuit
Table 19-2 Crystal Resonator Parameters
Frequency (MHz)
2
4
8
10
12
16
18
Rs max (
Ω
)
500
120
80
70
60
50
40
Co (pF)
7 pF max
Use a crystal resonator with a frequency equal to the system clock frequency (ø).
Notes on Board Design: When a crystal resonator is connected, the following points should be
noted:
Other signal lines should be routed away from the oscillator circuit to prevent induction from
interfering with correct oscillation. See figure 19-4.
When the board is designed, the crystal resonator and its load capacitors should be placed as close
as possible to the XTAL and EXTAL pins.
Figure 19-4 Example of Incorrect Board Design
XTAL
EXTAL
C
L2
C
L1
H8/3048 Series
Avoid
Signal A
Signal B
635
XTAL
L
Rs
C
L
C
0
EXTAL
AT-cut parallel-resonance type
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