AN2321 Freescale Semiconductor / Motorola, AN2321 Datasheet - Page 3

• Manufacturer Part Number: AN2321
• Description: Designing for Board Level Electromagnetic Compatibility
• Manufacturer: Freescale Semiconductor / Motorola

Receptor
Cost of EMC
MOTOROLA
Coupling also can occur with radiated electric and magnetic fields which are
common to all electrical circuits. Whenever current changes, electromagnetic
waves are generated. These waves can couple over to nearby conductors and
interfere with other signals within the circuit.
All electronic circuits are receptive to EMI transmissions. Most EMI are
received from conductive transients, although some are received from direct
radio frequency (RF) transmissions. In digital circuits, the most critical signals
are usually the most vulnerable to EMI. These include reset, interrupt, and
control line signals. Analog low-level amplifiers, control circuits, and power
regulators also are susceptible to noise interference.
To design for EMC and to meet EMC standards, the designer should minimize
emissions (RF energy exiting from products), and increase susceptibility or
immunity from emissions (RF energy entering into the products). Both emission
and immunity can be classified by radiated and conductive coupling, as shown
in
frequencies while a conducted coupling path will be more efficient in the lower
frequencies.
The most cost-effective way to design for EMC is to consider the EMC
requirement at the early stages of the design (see
It is unlikely that EMC will be the primary concern when the designer first
chooses the components, designs the circuit, and designs the PCB layout. But
if the suggestions in this application note are kept in mind, the possibility of poor
component choice, poor circuit design, and poor PCB layout can be reduced.
Designing for Board Level Electromagnetic Compatibility
Figure
Freescale Semiconductor, Inc.
For More Information On This Product,
PART 1: AN OVERVIEW OF ELECTROMAGNETIC INTERFERENCE AND COMPATIBILITY
Definition
1. The radiated coupling path will be more efficient in the higher
Product
Go to: www.freescale.com
Design
Circuit
Figure 2. Cost of EMC Measures
PCB Layout
Prototype
Compliance Test
Functional and
Figure
Production
Mass
2).
Product
Launch
AN2321/D
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