UPD784020 Datasheet, PDF (62/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
OSCILLATOR CHARACTERISTICS (TA = –40 to +85 °C, VDD = 2.7 to 5.5 V, VSS = 0 V)
Resonator
Recommended circuit
Parameter
Min.
Ceramic resonator
or crystal
Oscillator frequency (fXX)
4
Max.
16
Unit
MHz
VSS X1
X2
C1
C2
External clock
X1 input frequency (fX)
4
16
MHz
X1
X2
HCMOS
Inverter
X1 input rising and falling times
0
(tXR, tXF)
10
ns
X1 input high-level and low-
level widths (tWXH, tWXL)
10
125
ns
Caution When using the system clock generator, run wires in the portion surrounded by dotted lines
according to the following rules to avoid effects such as stray capacitance:
• Minimize the wiring.
• Never cause the wires to cross other signal lines.
• Never cause the wires to run near a line carrying a large varying current.
• Cause the grounding point of the capacitor of the oscillator circuit to have the same potential
as VSS. Never connect the capacitor to a ground pattern carrying a large current.
• Never extract a signal from the oscillator.
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