UPD784020 Datasheet, PDF (30/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

Fig. 8-3 Examples of Using Oscillator
(1) Crystal/ceramic oscillation
µ PD784021
VSS
X1
X2
mPD784020, 784021
H
(2) External clock
• When EXTC bit of OSTS = 1
• When EXTC bit of OSTS = 0
µ PD784021
X1
µ PD784021
X1
X2
µPD74HC04, etc.
Open
X2
Caution When using the clock generator, to avoid problems caused by influences such as stray
capacitance, run all wiring within the area indicated by the dotted lines according to the following
rules:
• Minimize the wiring length.
• Wires must never cross other signal lines.
• Wires must never run near a line carrying a large varying current.
• The grounding point of the capacitor of the oscillator circuit must always be at the same
potential as VSS. Never connect the capacitor to a ground pattern carrying a large current.
• Never extract a signal from the oscillator circuit.
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