Recommendations for Control of Radiated Emissions with isoPower Devices

iCoupler? digital isolators with integrated isolated power (isoPower?) employ isolated dc-to-dc converters that switch currents of ~700 mA at frequencies as high as 300 MHz. Operation at these high frequencies raise concerns about radiated emissions and conducted noise. PCB layout and construction is a very important tool for controlling radiated emissions and noise from applications containing isoPower components. This application note identifies the radiation mechanisms and offers specific guidance on addressing them.
Several standards for radiated emissions exist. In the U.S., the Federal Communications Commission (FCC) controls the standards and test methods. In Europe, the International Electrotechnical Commission (IEC) generates standards and CISPR test methods are used for evaluating emissions. The methods and pass/fail limits are slightly different under the two standards. Although this application note is written with reference to FCC standards, all results are applicable to both standards.