Main Clock Oscillator; Connecting A Crystal - Renesas RX100 Series User Manual

RX13T Group
9.3

Main Clock Oscillator

There are two ways of supplying the clock signal from the main clock oscillator: connecting an oscillator or the input of
an external clock signal.
9.3.1

Connecting a Crystal

Figure 9.2 shows an example of connecting a crystal.
A damping resistor (R ) should be added, if necessary. Since the resistor values vary depending on the resonator and the
d
oscillation drive capability, use values recommended by the resonator manufacturer. If use of an external feedback
resistor (R ) is directed by the resonator manufacturer, insert an R
f
instruction.
When connecting a resonator to supply the clock, the frequency of the resonator should be in the frequency range of the
resonator for the main clock oscillator described in Table 9.1 .
EXTAL
XTAL
Figure 9.2 Example of Crystal Connection
Table 9.3 Damping Resistance (Reference Values)
Frequency (MHz)
R (Ω)
d
Figure 9.3 shows an equivalent circuit of the crystal. Use a crystal that has the characteristics shown in Table 9.4 as a
reference.
Figure 9.3 Equivalent Circuit of Crystal
Table 9.4 Crystal Characteristics (Reference Values)
Frequency (MHz)
R max (Ω)
S
C max (pF)
0
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
R
f
R
d
2
0
L
XTAL
8
200
1.3
between EXTAL and XTAL by following the
f
C
L1
C C = C = 3 to 7 pF (reference value)
L2
L1 L2
8 16
0 0
C
L
R
S
C
0
12
120
1.3
9. Clock Generation Circuit
20
0
EXTAL
16
56
1.4
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