HD6473032F16 Datasheet, PDF (639/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 19 Clock Pulse Generator
19.2 Oscillator Circuit
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock
signal.
19.2.1 Connecting a Crystal Resonator
Circuit Configuration: A crystal resonator can be connected as in the example in figure 19.2.
The damping resistance Rd should be selected according to table 19.1 (1). Use capacitors with the
characteristics listed in table 19.1 (2) for external capacitors C_L1 and C_L2. An AT-cut parallel-
resonance crystal should be used.
C _L1
EXTAL
XTAL
Rd
C _L2
Figure 19.2 Connection of Crystal Resonator (Example)
If a crystal resonator with a frequency higher than 20 MHz is connected,the external load
capacitance values in table 20.1 (2) should not exceed 10[pF] Also,in order to improve the
accuracy of the oscillation frequency a thorough study of oscillation matching evaluation etc.
should be carried out when deciding the circuit constants.
Table 19.1 (1) Damping Resistance Value
Damping
Resistance
Value
2
Frequency f (MHz)
2 < f ≤ 4 4 < f ≤ 8 8 < f ≤ 10 10 < f ≤ 13 13 < f ≤ 16 16 < f ≤ 18 18 < f ≤ 25 20 < f ≤ 25
Rd (Ω)
1k 1k
500
200
100
0
0
0
0
Note: A crystal resonator between 2 MHz and 25 MHz can be used. If the chip is to be operated
at less than 2 MHz, the on-chip frequency divider should be used. (A crystal resonator of
less than 2 MHz cannot be used.)
Rev. 3.00 Mar 21, 2006 page 609 of 814
REJ09B0302-0300