M37702E6BFS Renesas Electronics America, M37702E6BFS Datasheet - Page 485

• 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

Fig. 15 Example for protecting analog input pin against noise by using thermistor
3. Wiring processing of analog input pin, analog power source pin and others
(1) Processing of analog input pin
Notes 1 : Make sure that the external circuit of the ANi pin is designed so that the ANi pin can
Thermistor
Reasons: Normally, the signal which is input to the analog input pin is an output signal from a
position closest possible to the microcomputer.
Insert a capacitor between the analog input pin and AVss pin at a position closest possible to the
Connect a resistor in series to the analog signal wire connecting to an analog input pin at the
AVss pin.
2 : This resistor is used to divide resistance from the thermistor.
be charged/discharged within 1 cycle of
sensor.
A sensor used to detect changes in event is in many cases located away from the board
on which the microcomputer is mounted. Accordingly, wiring from the sensor to the analog
input pin inevitably becomes long. This long wiring can serve as an antenna that pulls in
noise into the microcomputer, letting noise get into the analog input pin easily.
Additionally, if the capacitor between the analog input pin and AVss pin is grounded away
from the AVss pin, noise on that ground can get into the microcomputer via the capacitor.
Noise
N.G.
(Note 2)
7702/7703 Group User’s Manual
RI
CI
O.K
AN
O.K
AVss
Appendix 5. Countermeasures against noise
M37702
i
AD
.
Reference value
RI : Approximately 100 to 1000
CI : Approximately 100 to 1000 pF
APPENDIX
21–39