32186 datasheet(1027/1032 Pages) RENESAS

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SUMMARY OF PRECAUTIONS

Appendix 4

Appendix 4-37

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

Appendix 4.16 Notes on Noise

(3) Protection against signal lines that are the source of strong noise

Do not use any pin that will probably be subject to strong noise for an adjacent port near the oscillator. If the pin

can be left unused, set it for input and connect to GND via a resistor, or fix it to output and leave open. If the pin

needs to be used, it is recommended that it be used for input-only.

For protection against a still stronger noise source, set the adjacent port for input and connect to GND via a

resistor, and use those that belong to the same port group as much for input-only as possible. If greater

stability is required, do not use those that belong to the same port group and set them for input and connect to

GND via a resistor. If they need to be used, insert a limiting resistor for protection against noise.

If the ports or pins adjacent to the oscillator operate at high speed or are exposed to strong noise from an

external source, noise may affect the oscillator circuit, causing its oscillation to become instable.

Appendix Figure 4.16.8 Example Processing of a Noise-Laden Pin

XIN

XOUT

Noise

Fast switching

Adjacent pin/peripheral pin

(set for output)

Oscillator

External noise or

switching noise

Switching noise from an output pin applied directly to the port

Noise

Adjacent pin/peripheral pin

(set for input)

External noise from an input pin applied directly to the port

32186 Datasheet(PDF) 1027 Page - Renesas Technology Corp