3069RF-ZTAT Datasheet, PDF (711/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Crystal Resonator: Figure 19.3 shows an equivalent circuit of the crystal resonator. The crystal
resonator should have the characteristics listed in table 19.2.
XTAL
C_L
L
Rs
EXTAL
C₀
AT-cut parallel-resonance type
Figure 19.3 Crystal Resonator Equivalent Circuit
Table 19.2 Crystal Resonator Parameters
Frequency (MHz)
Rs max (Ω)
Co (pF)
10
30
7 (max)
12
30
7 (max)
16
20
7 (max)
18
20
7 (max)
20
20
7 (max)
25
20
7 (max)
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 _L2
Signal A Signal B
H8/3069R chip
XTAL
C _L1
EXTAL
Figure 19.4 Oscillator Circuit Block Board Design Precautions
Rev. 5.0, 09/04, page 689 of 978