UPD784218 Datasheet, PDF (33/92 Pages) NEC – 16-/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784218, 784218Y
Figure 8-3. Example of Using Main System Clock Oscillator
(1) Crystal/ceramic oscillation
(2) External clock
X2
X2
X1
VSS
Crystal resonator
or
ceramic resonator
External
X1
clock
µ PD74HCU04
Figure 8-4. Example of Using Subsystem Clock Oscillator
(1) Crystal oscillation
(2) External clock
VSS
XT2
32.768
kHz
XT1
XT2
External
clock
XT1
µPD74HCU04
Caution
When using the main system clock and subsystem clock oscillator, wire as following in the area
enclosed by the broken lines in Figures 8-3 and 8-4 to avoid an adverse effect from wiring
capacitance.
• Keep the wiring length as short as possible.
• Do not cross the wiring with 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 VSS. Do not
ground the capacitor to a ground pattern in which a high current flows.
• Do not fetch signals from the oscillator.
Note that the subsystem clock oscillator is designed as a low-amplitude circuit for reducing
current consumption.
Data Sheet U12304EJ2V0DS00
33