HD6473032F Datasheet, PDF (421/572 Pages) Hitachi Semiconductor – Hitachi Microcomputer

15.2 Oscillator Circuit
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock
signal.
15.2.1 Connecting a Crystal Resonator
Circuit Configuration: A crystal resonator can be connected as in the example in figure 15-2.
The damping resistance Rd should be selected according to table 15-1. An AT-cut parallel-
resonance crystal should be used.
C _L1
EXTAL
XTAL
Rd
C _L2
C_L1 = C _L2 = 10 pF to 22 pF
Figure 15-2 Connection of Crystal Resonator (Example)
Table 15-1 Damping Resistance Value
Frequency (MHz)
Rd (Ω)
2
4
8
10
12
16
1k
500
200 0
0
0
Crystal Resonator: Figure 15-3 shows an equivalent circuit of the crystal resonator. The crystal
resonator should have the characteristics listed in table 15-2.
XTAL
C_L
L
Rs
EXTAL
C_O
AT-cut parallel-resonance type
Figure 15-3 Crystal Resonator Equivalent Circuit
406