Oscillator Circuit; Connecting A Crystal Resonator - Renesas F-ZTAT H8 Series Hardware Manual

20.2

Oscillator Circuit

Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock
signal.
20.2.1

Connecting a Crystal Resonator

Circuit Configuration: A crystal resonator can be connected as in the example in figure 20.2.
The damping resistance Rd should be selected according to table 20.1. An AT-cut parallel-
resonance crystal should be used.
EXTAL
XTAL
Figure 20.2 Connection of Crystal Resonator (Example)
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 20.1 Damping Resistance Value
Damping Resistance
Value
Rd For products
(Ω) listed below*
H8/3048F
Note: A crystal resonator between 2 MHz and 18 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.)
* H8/3048ZTAT, H8/3048 mask-ROM, H8/3047 mask-ROM, H8/3045 mask-ROM,
H8/3044 mask-ROM
C
L1
Rd C
L2
2 < < < < f ≤ ≤ ≤ ≤ 4 4 < < < < f ≤ ≤ ≤ ≤ 8
2
1 k 500 200
1 k 1 k 500
Section 20 Clock Pulse Generator
C = C = 10 pF to 22 pF
L1 L2
Frequency f (MHz)
8 < < < < f ≤ ≤ ≤ ≤ 10 10 < < < < f ≤ ≤ ≤ ≤ 13 13 < < < < f ≤ ≤ ≤ ≤ 16 16 < < < < f ≤ ≤ ≤ ≤ 18
0 0
200 100
Rev. 7.00 Sep 21, 2005 page 655 of 878
0 0
0 —
REJ09B0259-0700