Datasheet

Section 22 Clock Pulse Generator
R01UH0310EJ0500 Rev. 5.00 Page 1135 of 1384
Sep 25, 2012
H8S/2426, H8S/2426R, H8S/2424 Group
22.2 Oscillator
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
22.2.1 Connecting a Crystal Resonator
A crystal resonator can be connected as shown in the example in figure 22.2. Select the damping
resistance R
d
according to table 22.1. When a crystal resonator is used, the range of its frequencies
is from 8 to 20 MHz.
Figure 22.3 shows the equivalent circuit of the crystal resonator. Use a crystal resonator that has
the characteristics shown in table 22.2.
EXTAL
XTAL
R
d
C
L2
C
L1
C
L1
= C
L2
= 10 to 22 pF
Figure 22.2 Connection of Crystal Resonator (Example)
Table 22.1 Damping Resistance Value
Frequency (MHz) 8 12 16 20
R
d
(Ω) 200 0 0 0
XTAL
C
L
EXTAL
C
0
LR
s
Figure 22.3 Crystal Resonator Equivalent Circuit