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Bits 1 and 0—Frequency Multiplication Factor (STC1, STC0): The STC bits specify the
frequency multiplication factor of the PLL circuit.
Bit 1
Bit 0
STC1
STC0
0
0
1
1
0
1
Note: A system clock frequency multiplied by the multiplication factor (STC1 and STC0) should
not exceed the maximum operating frequency defined in section 25 Electrical
Characteristics.
23.3
Oscillator
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
23.3.1
Connecting a Crystal Resonator
Circuit Configuration: A crystal resonator can be connected as shown in the example in figure
23-2. Select the damping resistance R
crystal should be used.
Figure 23-2 Connection of Crystal Resonator (Example)
Table 23-2 Damping Resistance Value
Frequency (MHz) 2
R
(Ω)
1 k
d
Crystal Resonator: Figure 23-3 shows the equivalent circuit of the crystal resonator. Use a
crystal resonator that has the characteristics shown in table 23-3.
844
Description
×1
×2
×4
Setting prohibited
according to table 23-2. An AT-cut parallel-resonance
d
EXTAL
XTAL
R
d
4
500
C
L1
C
C
L2
L1
8
12
200
0
= C
= 10 to 22pF
L2
16
20
0
0
(Initial value)
25
0
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