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ADM2507E - Emissions Issues

Question asked by ellisplace on Dec 9, 2011
Latest reply on Dec 9, 2011 by bkennedy

Can someone offer assitance with some emissions issues with the ADM2587E RS485 isoPower interface.


I have recently used this IC in my RS485 interface and upon testing found a serious emissions issue at around 405-420MHz.


I intend to follow the advise listed in the AN-0971 (information I wish I had fully investigated before prototype production)


Needless to say I require a modification to the current circuit which does not require an immediate board respin.


Please can you recommend any modifications which will help to reduce these emissions for the bout of EMC tesing in the next few days.


I also need some recommended Y2 safety capacitor values to try across the isolation barrier.


At the minute I have two on order:


150pF and 1000pF with a 0.15nH Inductance, I believe the 1000pF capacitor will be most effective at 410MHz. Am I correct in my calculations?


Due to my pressing test schedule, a rapid response will be greatly appreciated


Thank you and Kind Regards