M37702E6BFS Renesas Electronics America, M37702E6BFS Datasheet - Page 482

• 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

APPENDIX
Appendix 5. Countermeasures against noise
21–36
(2) Wiring of clock input/output pins
(3) Wiring of CNVss pin
Reasons: T h e m i c r o c o m p u t e r o p e r a t e s
When connecting the CNVss and Vss pins, connect them in the shortest possible distance.
Reasons: The voltage level on the CNVss
Separate the Vss pattern for oscillation purpose from the other Vss patterns. (Refer to Figure 19.)
Reduce the length of wiring connected to the clock input/output pins.
Connect the lead wire on the ground side of a capacitor connected to the oscillator and the
microcomputer’s Vss pin in the shortest possible distance (within 20 mm).
synchronously with the clock
generated by the oscillation circuit.
If noise gets into the clock input/
output pins, the clock waveform is
disturbed, which can cause the
microcomputer to malfunction or a
program runaway.
Furthermore, if noise causes a
potential difference between the
microcomputer’s Vss level and the
oscillator’s Vss level, the oscillator
cannot generate an exact clock.
p i n a f f e c t s t h e s e l e c t i o n o f
microcomputer’s processor modes.
I f n o i s e c a u s e s a p o t e n t i a l
difference between the voltage
levels of the CNVss and Vss pins
when these pins are connected,
the microcomputer’s processor
mode will become unstable,
causing the microcomputer to
malfunction or a program runaway.
7702/7703 Group User’s Manual
Fig. 11 Wiring of clock input/output pins
Fig. 12 Wiring of CNVss pin
M37702
CNVss
N.G.
Vss
Noise
N.G.
Vss
X
X
M37702
Noise
IN
OUT
M37702
CNVss
O.K.
O.K.
Vss
X
X
Vss
M37702
IN
OUT