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4. Clock Pulse Generators
The clock signals available for use by peripheral modules are φ/2, φ/4, φ/8, φ/16, φ/32, φ/64,
φ/128, φ/256, φ/512, φ/1024, φ/2048, φ/4096, φ/8192, φ
and φ
/128. The clock requirements differ from one module to another.
W
4.2
System Clock Generator
Clock pulse can be supplied to the system clock divider either by connecting a crystal or ceramic
oscillator, or by providing external clock input.
Connecting a Crystal Oscillator: Figure 4.2 shows a typical method of connecting a crystal
oscillator.
Figure 4.3 shows the equivalent circuit of a crystal oscillator. An oscillator having the
characteristics given in table 4.1 should be used.
OSC
1
Table 4.1
Crystal Oscillator Parameters
Frequency (MHz)
R
(max)
s
C
(max)
0
Rev.3.00 Jul. 19, 2007 page 94 of 532
REJ09B0397-0300
OSC
1
R
f
OSC
2
Figure 4.2 Typical Connection to Crystal Oscillator
L
S
Figure 4.3 Equivalent Circuit of Crystal Oscillator
2
500 Ω
7 pF
, φ
/2, φ
W
W
C
1
R = 1 M
f
C = C = 12 pF ±20%
C
1
2
2
C
S
R
C
0
4
100 Ω
7 pF
/4, φ
/8, φ
/16, φ
/32, φ
W
W
W
W
Ω
±20%
S
OSC
8
10
50 Ω
30 Ω
7 pF
7 pF
/64,
W
2
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