HD64F2149 Datasheet, PDF (738/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

C_L1
EXTAL
XTAL
R_d
C_L2
C_L1 = C_L2 = 10 to 22pF
Figure 23.2 Connection of Crystal Resonator (Example)
Table 23.2 Damping Resistance Value
Frequency (MHz)
2
R_d (Ω)
1k
4
8
10
500
200
0
Crystal resonator: Figure 23.3 shows the equivalent circuit of the crystal resonator. Use a crystal
resonator that has the characteristics shown in table 23.3 and the same frequency as the system
clock (ø).
XTAL
C_L
L
R_s
EXTAL
C₀
AT-cut parallel-resonance type
Figure 23.3 Crystal Resonator Equivalent Circuit
Table 23.3 Crystal Resonator Parameters
Frequency (MHz)
2
4
8
10
R_S max (Ω)
C₀ max (pF)
500
120
80
70
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 23.4.
When designing the board, place the crystal resonator and its load capacitors as close as possible
to the XTAL and EXTAL pins.
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