HD64F3337YCP16V Datasheet, PDF (134/749 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

C_L1
EXTAL
XTAL
Rd
C_L2
C_L1 = C _L2 = 10 pF to 22 pF
Figure 6.8 Connection of Crystal Oscillator (Example)
Table 6.5 Damping Resistance
Frequency (MHz)
Rd max (Ω)
2
4
8
10
1k
500
200
0
Crystal Oscillator: Figure 6.9 shows an equivalent circuit of the crystal resonator. The crystal
resonator should have the characteristics listed in table 6.6.
XTAL
C_L
L
Rs
EXTAL
C₀
AT-cut parallel resonating crystal
Figure 6.9 Equivalent Circuit of External Crystal
Table 6.6 External Crystal Parameters
Frequency (MHz)
Rs max (Ω)
C₀ (pF)
2
500
7 pF max
4
120
7 pF max
8
80
7 pF max
10
70
7 pF max
Use a crystal with the same frequency as the desired system clock frequency (ø).
Note on Board Design: When an external crystal is connected, other signal lines should be kept
away from the crystal circuit to prevent induction from interfering with correct oscillation. See
figure 6.10. The crystal and its load capacitors should be placed as close as possible to the XTAL
and EXTAL pins.
102