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17.2
Oscillator
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
17.2.1
Connecting Crystal Resonator
A crystal resonator can be connected as shown in the example in figure 17.2. Select the damping
resistance R
according to table 17.1. An AT-cut parallel-resonance type should be used.
d
When the clock is provided by connecting a crystal resonator, a crystal resonator having a
frequency of 8 to 18 MHz should be connected.
Figure 17.2 Connection of Crystal Resonator (Example)
Table 17.1 Damping Resistance Value
Frequency (MHz)
R
(Ω)
d
Figure 17.3 shows an equivalent circuit of the crystal resonator. Use a crystal resonator that has
the characteristics shown in table 17.2.
XTAL
EXTAL
XTAL
R
d
8
200
L
Figure 17.3 Crystal Resonator Equivalent Circuit
C
L1
C
C
= C
L2
L1
L2
12
0
C
L
R
s
AT-cut parallel-resonance type
C
0
Rev.2.00 Jun. 28, 2007 Page 557 of 666
Section 17 Clock Pulse Generator
= 10 to 22 pF
18
0
EXTAL
REJ09B0311-0200
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