Oscillator; Connecting Crystal Resonator; Figure 23.2 Typical Connection To Crystal Resonator; Figure 23.3 Equivalent Circuit Of Crystal Resonator - Renesas H8S Series Hardware Manual

Section 23 Clock Pulse Generator
23.1

Oscillator

Clock pulses can be supplied either by connecting a crystal resonator or by providing external
clock input.
23.1.1

Connecting Crystal Resonator

Figure 23.2 shows a typical method for connecting a crystal resonator. An appropriate damping
resistance R , given in table 23.1 should be used. An AT-cut parallel-resonance crystal resonator
d
should be used.
Figure 23.3 shows an equivalent circuit of a crystal resonator. A crystal resonator having the
characteristics given in table 23.2 should be used.
The frequency of the crystal resonator should be the same as that of the system clock (φ).

Figure 23.2 Typical Connection to Crystal Resonator

Table 23.1 Damping Resistor Values

Frequency (MHz)
R (Ω)
d
XTAL
Rev. 3.00 Jul. 14, 2005 Page 850 of 986
REJ09B0098-0300
EXTAL
XTAL
R
d
4 8
500 200
C
L
L
C
0

Figure 23.3 Equivalent Circuit of Crystal Resonator

C
L1
C C = C
L2 L1 L2
10 12
0 0
R
s
EXTAL
AT-cut parallel-resonance crystal resonator
= 10 to 22 pF
16
0
20
0