Fig. 3.4.3 Wiring For Clock I/O Pins - Renesas 4513 User Manual

(3) Wiring for clock input/output pins
• Make the length of wiring which is connected
to clock I/O pins as short as possible.
• Make the length of wiring across the
grounding lead of a capacitor which is
connected to an oscillator and the V
of a microcomputer as short as possible.
• Separate the V
from other V
SS
Noise
N.G.

Fig. 3.4.3 Wiring for clock I/O pins

Reason
If noise enters clock I/O pins, clock
waveforms may be deformed. This may
cause a program failure or program runaway.
Also, if a potential difference is caused by
the noise between the V
microcomputer and the V
oscillator, the correct clock will not be input
in the microcomputer.
pattern only for oscillation
SS
patterns.
X X
IN IN
X X
OUT OUT
V V
SS SS
O.K.
level of a
SS
level of an
SS
4513/4514 Group User's Manual
(4) Wiring to CNV
Connect the CNV
the shortest possible wiring.
Reason
pin
The operation mode of a microcomputer is
SS
influenced by a potential at the CNV
If a potential difference is caused by the
noise between pins CNV
operation mode may become unstable. This
may cause a microcomputer malfunction or
a program runaway.
CNV
V
Fig. 3.4.4 Wiring for CNV
APPENDIX
3.4 Notes on noise
pin
SS
pin to the V
SS
Noise
CNV
SS
SS
N.G.
pin
SS
pin with
SS
pin.
SS
and V , the
SS SS
SS
V
SS
O.K.
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