AN898/1100

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AN898

APPLICATION NOTE

EMC GENERAL INFORMATION

by Microcontroller Division Applications

INTRODUCTION

Because many electronic circuits are in proximity to each other, it is essential that their design

is not affected by external noise sources and that the circuit itself is not a noise source af-

fecting other circuits. This relationship is known as electromagnetic compatibility or EMC.

Sources of electromagnetic noise are numerous and have both natural and man-made ori-

gins.

Natural sources below 10 MHz are dominated by the atmospheric noise generated by elec-

trical storms. Above 10 MHz, natural sources consist primarily of cosmic noise and solar radi-

ation.

Man-made noise include AM, FM, TV and other broadcast transmitters, mobiles radios but

also computing devices, motors, appliances, power lines, auto ignition systems and many

others. With the proliferation of these sources (particularly in urban areas), electromagnetic

noise has reached important levels.

For detailed information regarding EMC guidelines for microcontroller - based applications,

please refer to AN901.

Figure 1. Electromagnetic Radiation Sources

NATURALORIGIN

MAN-MADE ORIGIN

ELECTROMAGNETICRADIATION

VR02102A

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