UPD78320 Datasheet, PDF (65/88 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLER

µPD78320, 78322
OSCILLATOR CHARACTERISTICS (TA = –10 to +70 °C, VDD = +5 V ±10 %, VSS = 0 V)
Resonator
Recommended Circuit
Parameter
MIN. MAX. Unit
Ceramic resonator
or
crystal resonator
X2
X1 VSS
C2
C1
Oscillation frequency (fXX)
8
16
MHz
External clock
X1
X2
HCMOS
Invertor
or
X1
X2
Open
HCMOS
Invertor
X1 input frequency (fX)
8
16
MHz
X1 input rise/fall time (tXR, tXF)
0
20
ns
X1 input high/low level width
(tWXH , tWXL)
25
80
ns
Caution When using the system clock oscillation circuit, wire the part encircled in the dotted line in the following
manner to avoid the influence of the wiring capacity, etc.
• Make the wiring as short as possible.
• Avoid intersecting other signal conductors. Avoid approaching lines in which very high fluctuating
currents run.
• Make sure that the grounding point of the oscillation circuit capacitor always has the same electrical
potential as VSS. Avoid grounding with a grand pattern in which very high currents run.
• Do not fetch signals from the oscillation circuit.
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