NEC 78K0 Series User Manual page 147

Cautions 1. When using the X1 oscillator and XT1 oscillator, wire as follows in the area enclosed by the
broken lines in the Figures 6-9 and 6-10 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
not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
Note that the XT1 oscillator is designed as a low-amplitude circuit for reducing power
consumption.
Figure 6-11 shows examples of incorrect resonator connection.
Figure 6-11. Examples of Incorrect Resonator Connection (1/2)
(a) Too long wiring
V
SS
Remark When using the subsystem clock, replace X1 and X2 with XT1 and XT2, respectively. Also, insert
resistors in series on the XT2 side.
CHAPTER 6 CLOCK GENERATOR
X1 X2
Preliminary User's Manual U17260EJ3V1UD
(b) Crossed signal line
PORT
V X1 X2
SS
. Do
SS
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