HD6432633 Datasheet, PDF (1029/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

Table 23B-2 Damping Resistance Value
Frequency (MHz) 2
4
8
12
16
20
25
R_d (Ω)
1k
500
200
0
0
0
0
Crystal Resonator: Figure 23B-3 shows the equivalent circuit of the crystal resonator. Use a
crystal resonator that has the characteristics shown in table 23B-3.
XTAL
C_L
L
R_s
EXTAL
C₀
AT-cut parallel-resonance type
Figure 23B-3 Crystal Resonator Equivalent Circuit
Table 23B-3 Crystal Resonator Parameters
Frequency (MHz) 2
4
8
12
16
20
25
R_S max (Ω)
500
120
80
60
50
40
40
C₀ max (pF)
7
7
7
7
7
7
7
Note 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 23B-4.
When designing the board, place the crystal resonator and its load capacitors as close as possible
to the XTAL and EXTAL pins.
Avoid
C_L2
Signal A Signal B
H8S/2633R Series
XTAL
EXTAL
C_L1
Figure 23B-4 Example of Incorrect Board Design
975