There are 100s of articles on the subject already published. http://www.maxim-ic.com/appnotes.cfm/appnote_number/639/ln/en This is but one of them. The three main considerations are: What level of protection is afforded that the protecting device can handle. (Speed, polarity, recovery, energy level capability.) What is the effect of adding ESD protection to normal performance (capacitance loading, leakage etc.) What does it cost in board real estate and how much it cost. Your circuit determines what is required. (Part's susceptibility, speed of operation, harsh environment, etc.) Steve Salkow -----Original Message----- From: Steve Mitchell [mailto:SteveMitchell@xxxxxxxxxx] Sent: Friday, October 03, 2003 2:45 AM To: Signal Integrity Forum Cc: Nigel.Hughes@xxxxxxxxxx Subject: [SI-LIST] ESD Issues Dear Forum, What are the different issues between usage of Zeners and Varistors for ESD protection Regard Steve ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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