Table of Contents
Advertisement
Section 19 Clock Pulse Generator
XTAL
Table 19.2 Crystal Resonator Parameters
Frequency (MHz)
Rs max (Ω)
Co (pF)
Use a crystal resonator with a frequency equal to the system clock frequency (φ).
Notes on Board Design: When a crystal resonator is connected, the following points should be
noted:
Other signal lines should be routed away from the oscillator circuit to prevent induction from
interfering with correct oscillation. See figure 19.4.
When the board is designed, the crystal resonator and its load capacitors should be placed as close
as possible to the XTAL and EXTAL pins.
Avoid
C
C
Rev. 4.00 Jan 26, 2006 page 668 of 938
REJ09B0276-0400
C
L
Figure 19.3 Crystal Resonator Equivalent Circuit
2
4
500
120
7 pF max
Signal A
L2
L1
Figure 19.4 Example of Incorrect Board Design
L
Rs
AT-cut parallel-resonance type
C
0
8
10
12
80
70
60
Signal B
EXTAL
16
18
50
40
H8/3067 Group
XTAL
EXTAL
20
40
Advertisement
Table of Contents
