clock ATMEL AT91SAM9260

hi,

anyone has worked with ATMEL AT91SAM9260, in particular for compliance with the radiated Emissions, class B limit, EN5022 ?
I have a problem with emissions from the clock pin (100Mhz).
About a peak at 200Mhz,  I can not lower it. The pin is connected with two ram memories with a 47 ohm series terminated.

 

 

dopatissimo 4 years 4 months 12 days

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Answered byOld_School 4 years 1 month 5 days
Hi Dopatissimo,

   The first thing to try is increase your resistor from 47 ohm to 75 ohm.  Lower rise time produces lower amplitude harmonics.

   Second, the amount of radiated emissions is directly related to the sheilding of your box or enclosure.  100 MHz clock and data bus should be routed on internal layer covered above and below with solid GND plane.  Or your box should be metal and all openings should be covered with metal connectors and metal backshells.

Cheers,
O.S.