HD6413008VF25 Datasheet, PDF (496/688 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

17. Clock Pulse Generator
Table 17.1 (2) External Capacitance Values
External Capacitance Value
Frequency f (MHz)
C = C (pF)
L1
L2
5 V Version
20 < f ≤ 25
10
2 ≤ f ≤ 20
10 to 22
3 V Version
2 ≤ f ≤ 16
22
16 ≤ f ≤ 25
10
Crystal Resonator: Figure 17.3 shows an equivalent circuit of the crystal resonator. The crystal
resonator should have the characteristics listed in table 17.2.
XTAL
C_L
L
Rs
EXTAL
C₀
AT-cut parallel-resonance type
Figure 17.3 Crystal Resonator Equivalent Circuit
Table 17.2 Crystal Resonator Parameters
Frequency (MHz)
Rs max (Ω)
Co (pF)
2
4
8
10 12 16 18 20 25
500 120 80 70 60 50 40 40 40
7 pF 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 17.4.
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.
Rev.4.00 Aug. 20, 2007 Page 450 of 638
REJ09B0395-0400