Oscillator; Connecting A Crystal Oscillator; Figure 26.2 Typical Connection To Crystal Resonator; Figure 26.3 Equivalent Circuit Of Crystal Resonator - Renesas H8S/2158 User Manual

Section 26 Clock Pulse Generator
The subclock input is controlled by software according to the EXCLE bit setting in the low power
control register. For details on the low power control register, see section 27.1.2, Low-Power
Control Register (LPWRCR).
26.1

Oscillator

Clock pulses can be supplied either by connecting a crystal resonator or by providing external
clock input.
26.1.1

Connecting a Crystal Oscillator

Figure 26.2 shows a typical method of connecting a crystal resonator. An appropriate damping
resistance R , given in table 26.1, should be used. An AT-cut parallel-resonance crystal resonator
d
should be used.
Figure 26.3 shows the equivalent circuit of a crystal resonator. A crystal resonator having the
characteristics given in table 26.2 should be used.
A crystal resonator with frequency identical to that of the system clock (φ) should be used.

Figure 26.2 Typical Connection to Crystal Resonator

Table 26.1 Damping Resistance Values

Frequency (MHz)
(Ω Ω Ω Ω )
R
d
XTAL

Figure 26.3 Equivalent Circuit of Crystal Resonator

Rev. 3.00 Jan 25, 2006 page 762 of 872
REJ09B0286-0300
C
L1
EXTAL
XTAL
R C
d L2
5 8
300 200
C
L
L
AT-cut parallel-resonance crystal resonator
C
0
C = C = 10 to 22 pF
L1 L2
10 12
0 0
R
s
EXTAL
16 20
0 0
25
0