M16C62_M Datasheet, PDF (608/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

Appendix 5
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
1.2 Connection of bypass capacitor across Vss line and Vcc line
Connect an approximately 0.1 µF bypass capacitor across the Vss line and the Vcc line as follows:
• Connect a bypass capacitor across the Vss pin and the Vcc pin at equal length.
• Connect a bypass capacitor across the Vss pin and the Vcc pin with the shortest possible wiring.
• Use lines with a larger diameter than other signal lines for Vss line and Vcc line.
• Connect the power source wiring via a bypass capacitor to the Vss pin and the Vcc pin.
VCC
VCC
VSS
VSS
N.G.
O.K.
Figure 1.2.1. Bypass capacitor across the Vss line and the Vcc line
1.3 Wiring to analog input pins
• Connect an approximately 100 Ω to 1 kΩ resistor to an analog signal line which is connected to an analog
input pin in series. Besides, connect the resistor to the microcomputer as close as possible.
• Connect an approximately 1000 pF capacitor across the Vss pin and the analog input pin. Besides,
connect the capacitor to the Vss pin as close as possible. Also, connect the capacitor across the analog
input pin and the Vss pin at equal length.
q Reason
Signals which is input in an analog input pin (such as an A-D converter/comparator input pin) are usually
output signals from sensor. The sensor which detects a change of event is installed far from the printed
circuit board with a microcomputer, the wiring to an analog input pin is longer necessarily. This long wiring
functions as an antenna which feeds noise into the microcomputer, which causes noise to an analog input
pin.
Noise
Thermistor
(Note)
Microcomputer
Analog
input pin
N.G.
O.K.
VSS
Note: The resistor is used for dividing
resistance with a thermistor.
Figure 1.3.1. Analog signal line and a resistor and a capacitor
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