M37702E6BFS Renesas Electronics America, M37702E6BFS Datasheet - Page 487

• Manufacturer Part Number: M37702E6BFS
• Description: EPROM MCU/8BIT CMOS EMULATION CH
• Manufacturer: Renesas Electronics America

Specifications of M37702E6BFS

• Accessory Type: Emulator EPROM MCU
• For Use With/related Products: 7702
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4. Consideration to oscillator
The oscillator that generates the fundamental clock of the microcomputer’s operation requires careful
consideration not to be affected by the other signals.
(1) Isolation from signal wires where a large current flows
(2) Isolation from signal wires whose levels change rapidly
The signal wires where a large current exceeding the microcomputer’s current limits accepted flows
must be located as far away from the microcomputer (especially the oscillator) as possible.
Reasons: A system using a microcomputer
Reasons: The signal wires whose voltage
possible.
noise-susceptible signal wires.
The signal wires whose levels change rapidly must be located as far away from the oscillator as
Make sure that signal wires whose levels change rapidly do not cross any other clock-related or
contains signal wires to control, for
example, motors, LEDs, and thermal
heads. When a large current flows
in these signal wires, noise due to
mutual inductance is generated.
levels change rapidly tend to affect
other signal wires as the signal level
changes from high to low or from
low to high. Especially if these signal
wires cross a clock-related signal
wire, they can disturb the clock
w a v e f o r m ,
microcomputer to malfunction or a
program runaway.
c a u s i n g
7702/7703 Group User’s Manual
t h e
Appendix 5. Countermeasures against noise
Fig. 17 Connection of signal wires where a large
Fig. 18 Wiring of rapidly level changing signal wire
Must not cross
other signal wires.
Mutual inductance
current flows
changes rapidly
I/O pin for a signal whose level
current
Large
M
X
X
APPENDIX
Vss
M37702
IN
OUT
X
Vss
X
M37702
IN
OUT
21–41