Oscillator; Connecting Crystal Resonator; Figure 19.2 Typical Connection To Crystal Resonator; Figure 19.3 Equivalent Circuit Of Crystal Resonator - Renesas H8S/2111B Hardware Manual

19.1

Oscillator

Clock pulses can be supplied either by connecting a crystal resonator, or by providing external
clock input.
19.1.1

Connecting Crystal Resonator

Figure 19.2 shows a typical method of connecting a crystal resonator. An appropriate damping
resistance R , given in table 19.1, should be used. An AT-cut parallel-resonance crystal resonator
d
should be used.
Figure 19.3 shows the equivalent circuit of a crystal resonator. A resonator having the
characteristics given in table 19.2 should be used.
A crystal resonator with frequency identical to that of the system clock (φ) should be used.

Figure 19.2 Typical Connection to Crystal Resonator

Table 19.1 Damping Resistance Values

Frequency (MHz)
R (Ω)
d
XTAL

Table 19.2 Crystal Resonator Parameters

Frequency (MHz)
R (max) (Ω)
S
C (max) (pF)
0
Rev. 1.00, 05/04, page 456 of 544
EXTAL
XTAL
R
d
4
500
C
L
L
C
0

Figure 19.3 Equivalent Circuit of Crystal Resonator

4
120
7
C
L1
C = C
C
L1 L2
L2
8
200
R
s
EXTAL
AT-cut parallel-resonance crystal resonator
8
80
7
= 10 to 22 pF
10
0
10
70
7