UPD78320 Datasheet, PDF (34/88 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLER

µPD78320, 78322
(a) Crystal oscillator
Figure 3-2. Externally-Mounted System Clock Oscillator
µ PD78322
X2
X1
VSS
(b) External clock
(i) When the inverted phase of an external clock
to be input to the X1 pin is input to the X2 pin
External
Clock
µ PD78322
X1
(ii) When X2 pin is left open
External
Clock
µ PD78322
X1
X2
Open X2
Cautions 1. When the system clock oscillator is used, the following points should be noted concerning wiring
within broken lines shown in Figure 3-2, in order to prevent the effects of wiring capacitance, etc.
• Keep the wiring as short as possible.
• Do not cross any other signal lines, and keep clear of lines in which a high fluctuating current flows.
• Ensure that oscillator capacitor connection points are always at the same potential as VSS.
Do not ground in a ground pattern in which a high current flows.
• Do not take a signal from the oscillator.
2. When an external clock is input to the X1 pin and the X2 pin is left open, ensure that no loads such
as wiring capacitance are connected to the X2 pin.
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