Oscillator; Connecting A Crystal Resonator - Renesas H8S Series Hardware Manual

20.3

Oscillator

Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
20.3.1

Connecting a Crystal Resonator

Circuit Configuration: A crystal resonator can be connected as shown in the example in figure 20-2. Select the damping
resistance R according to table 20-2. An AT-cut parallel-resonance crystal should be used.
d
Table 20-2 Damping Resistance Value
Frequency (MHz)
R (Ω)
d
Crystal Resonator: Figure 20-3 shows the equivalent circuit of the crystal resonator. Use a crystal resonator that has the
characteristics shown in table 20-3 and the same resonance frequency as the system clock (ø).
Table 20-3 Crystal Resonator Parameters
Frequency (MHz)
R max (Ω)
S
C max (pF)
0
EXTAL
XTAL
R
d
Figure 20-2 Connection of Crystal Resonator (Example)
2 4
1k 500
L
XTAL
Figure 20-3 Crystal Resonator Equivalent Circuit
2 4
500 120
7 7
C
L1
C C = C
L2 L1 L2
8 10
200 0
C
L
R
s
EXTAL
AT-cut parallel-resonance type
C
0
8 10
80 70
7 7
= 10 to 22 pF
12 16 20
0 0 0
12 16 20
60 50 40
7 7 7
Rev.6.00 Oct.28.2004 page 663 of 1016
REJ09B0138-0600H