Hi Steve, huh? - I am surprised that you say that varistors have the slowest response of protection devices. Are you aware of the latest surface mount devices like those at http://www.amotech.co.kr/eng/smd_varistor.html. I find it hard to conceive that it is possible they could possible have any more inductance than other 0402 components (eg. an 0402 capacitor). I actually have heard the opposite of what you say against non-CSP zeners - ie. die to their packaging the die is connected to the package terminals with effectively a tiny bit of wire, that introduces a whole heap of inductance. Were you not aware of surface mount varistors? Cheers, Nigel. At 09:44 14/10/2003, steve weir wrote: >Nigel, varistors have the slowest response of available devices as they >have always been fairly inductive. Varistors also have traditionally had >the least well controlled hold and breakdown voltage tolerances. General >purpose zeners have a soft VI curve, and limited energy handling >capacity. Transzorb type devices are the most expensive but handle high >energy surges, have comparatively very flat VI curves, low inductance, but >alas higher prices. Vendors have device performance curves and lots of >application notes. > >At 09:30 AM 10/14/2003 +0100, Nigel Hughes wrote: > >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 > ======================================================================= 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