The purpose is to allow any common mode AC current to return through the AC cap to chasis gnd. Another purpose is to avoid common mode current on the system power plane to couple through the differential trace our as radiation. >2.0 Ethernet PHY signals should refer to only transformer secondary supply >voltage PLANE. > > >-----If System designer ignores the above point what will happen? ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu