Connecting A Crystal Oscillator - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

21.2.1

Connecting a Crystal Oscillator

A crystal oscillator can be connected as shown in the example in figure 21.2. Select the damping
resistance R according to table 20.1. An AT-cut parallel-resonance type should be used.
d
Figure 21.3 shows the equivalent circuit of the crystal oscillator. Use a crystal oscillator that has
the characteristics shown in table 21.2.
EXTAL
XTAL
Figure 21.2 Connection of Crystal Oscillator (Example)
Table 21.1 Damping Resistance Value
Frequency (MHz)
R (Ω)
d
XTAL
Table 21.2 Crystal Oscillator Characteristics
Frequency (MHz)
R max (Ω)
S
C max (pF)
0
Rev. 1.0, 09/01, page 796 of 904
R
d
8 12
200 0
L
Figure 21.3 Crystal Oscillator Equivalent Circuit
8 12
80 60
7 7
C
L1
C C
L2 L1
16
0
C
L
R
s
AT-cut parallel-resonance type
C
0
16
50
7
= C = 10 to 22 pF
L2
20
0
EXTAL
20
40
7
25
0
25
40
7