CHAPTER 5 CLOCK GENERATOR
Preliminary User’s Manual U19014EJ1V0UD
94
5.4 System Clock Oscillator
5.4.1 X1 oscillator
The X1 oscillator oscillates with a crystal resonator or ceramic resonator (1 to 20 MHz) connected to the X1 and X2
pins.
Figure 5-11 shows an example of the external circuit of the X1 oscillator.
Figure 5-11. Example of External Circuit of X1 Oscillator (Crystal or Ceramic Oscillation)
V
SS
X1
X2
Crystal resonator
or
ceramic resonator
Cautions 1. When using the X1 oscillator, wire as follows in the area enclosed by the broken lines in the
Figure 5-11 to avoid an adverse effect from wiring capacitance.
• Keep the wiring length as short as possible.
• Do not cross the wiring with the other signal lines. Do not route the wiring near a signal
line through which a high fluctuating current flows.
• Always make the ground point of the oscillator capacitor the same potential as V
SS
. Do
not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
Figure 5-12 shows examples of incorrect resonator connection.
Figure 5-12. Examples of Incorrect Resonator Connection (1/2)
(a) Too long wiring
(b) Crossed signal line
X2
V
SS
X1
X1
V
SS
X2
PORT
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