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Ton, Yes, the USB cable/interface should be tested for conducted immunity.
USB cables are shielded (screened) so I believe the "Direct Coupling" method would be the method to use. Brian Kunde LECO Compliance Testing Center ____________________Reply Separator____________________ Subject: Conducted immunity of a USB port Author: [email protected] List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: 11/18/03 6:14 PM Dear group, I have the following questions on testing a USB port for conducted immunity 1) USB extension cables are available in the consumer market. The USB 1.0 spec limits the cable length to 5.0m. Therefor I believe that the conducted immunity test is required even if the cable length of the DUT is less than 3m, unles a restriction is made in the user manual.. Is that correct? 2) I tested conducted immunity using a CDN-S9 with home-made adaptors from DB9 to USB using 4 pins of the DB-9 and the screen connection. I assume that this should give a representative result? For information: this does not work for hi-speed USB because of the LPF in the CDN. 3) Are CDN's for USB available? Or is it better to use an EM clamp? kind regards, Ton Bouw This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: with the single line:Title: Re:Conducted immunity of a USB port
Ton,
Yes, the USB cable/interface should be tested for conducted immunity.
USB cables are shielded (screened) so I believe the "Direct Coupling" method
would be the method to use.
Brian Kunde
LECO
Compliance Testing Center
____________________Reply Separator____________________
Subject: Conducted immunity of a USB port
Author: [email protected]
Date: 11/18/03 6:14 PM
Dear group,
I have the following questions on testing a USB port for conducted immunity
1) USB extension cables are available in the consumer market. The USB 1.0 spec limits the cable length to 5.0m. Therefor I believe that the conducted immunity test is required even if the cable length of the DUT is less than 3m, unles a restriction is made in the user manual.. Is that correct?
2) I tested conducted immunity using a CDN-S9 with home-made adaptors from DB9 to USB using 4 pins of the DB-9 and the screen connection. I assume that this should give a representative result? For information: this does not work for hi-speed USB because of the LPF in the CDN.
3) Are CDN's for USB available? Or is it better to use an EM clamp?
kind regards,
Ton Bouw
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