Hi Nigel, The structure's inductance is a limiting factor. Leaded MLVs are fairly inductive. Surface mount MLV's have significantly reduced the inductance. X2Y just licensed Maida Development and they are combining the low inductance X2Y structure with their MOV material to further reduce the inductance. You get the added benefit of space reduction by combining two devices into a single structure. Best regards, Tony Anthony -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Nigel Hughes Sent: Tuesday, October 14, 2003 4:30 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] ESD protection devices Hello Forum, I am trying to compare and evaluate ESD protection devices. According to the device physics, what are the things that limit the speed at which a zener or varistor responds? I have heard previously that a varistor responds quicker but read that the device itself is damaged when an ESD event passes through it. However others say that with the new multi-layer structure of surface mount devices, the damage is negligible (if occurring at all). Has anybody got a better perspective of what the truth actually is. A bit of background supporting information would be helpful. Thanks, Nigel. ======================================================================= O O O Nigel Hughes Tel +44 1763 266266 O O O Terminals Fax +44 1763 261216 O O O TTPCom Ltd. Melbourn Science Park, Cambridge Rd., Melbourn, Royston, Herts SG8 6HQ UK nigel.hughes@xxxxxxxxxx ======================================================================= ------------------------------------------------------------------ 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