Follow the current. Observe the voltage. Steve. Vinod Kumar wrote: > Hi All, > > For handheld battery operated devices, we don't have a GND EARTH normally. > So in this case how should we connect the ESD device? > > We generally have a separate noise GND and all the ESD devices are > terminated to this. This GND is connected to signal GND at one point. But as > explained at http://emcesd.com/tt2009/tt020309.htm , if the common GND > point is far away from ESD device, it can render the protection ineffective. > > But if a large single GND plane is used and all the ESD devices are > connected to this ground, the excess energy will be shunted to this GND. > Will this not affect the other devices through GND pins of ICs which do not > have any ESD protection (as all the devices are using same GND)? > > Thanks in advance for your suggestions. > > Regards, > Vinod > > > > ----- Original Message ----- > From: "Doug Smith" <doug@xxxxxxxxxx> > To: "Vivekkumar M-ERS,HCLTech" <Vivekkumarm@xxxxxx> > Cc: "Arun Kumar P N" <arun@xxxxxxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx> > Sent: Thursday, December 10, 2009 12:06 AM > Subject: [SI-LIST] Re: ESD protectioin at a Digital Input > > > >> Hi Arun, Vivek, and the group, >> >> The board layout can easily erase any protection that the protection >> device offers. The actual voltage the IC sees can easily be 10, 100 or >> more times the clamp voltage depending on the board layout. One such >> layout problem is described in my Technical Tidbit for February 2009: >> http://emcesd.com/tt2009/tt020309.htm . However, there are many ways to >> render the protection device ineffective. >> >> Doug >> >> Vivekkumar M-ERS,HCLTech wrote: >> >>> Arun Kumar, >>> >>> Clamping voltage of an ESD should be closely related to the voltage max >>> the pin of the IC can withstand. Even though the IC supports 1KV ESD >>> protection, check with the manufacturer about the max voltage the pins of >>> the IC can withstand. Say manufacturer suggests 10V. Then at max you can >>> have 15V as clamping voltage. >>> >>> The danger of having 200V voltage as clamping voltage is that when a >>> large surge occurs, the IC is subjected to this much voltage and it may >>> damage the IC. >>> >>> ESD diodes, another the important factor we need to consider is how much >>> energy(power dissipation in wattage) it can withstand. This is based on >>> the open and short circuit voltages and were your end equipment is >>> placed. >>> >>> Find attached app note from semtech. >>> >>> http://www.semtech.com/images/datasheet/transient_immunity_standards_iec_61000-4-x.pdf >>> >>> Regards >>> Vivek >>> >>> ________________________________________ >>> From: si-list-bounce@xxxxxxxxxxxxx [si-list-bounce@xxxxxxxxxxxxx] On >>> Behalf Of Arun Kumar P N [arun@xxxxxxxxxxxxxxxx] >>> Sent: Wednesday, December 09, 2009 4:16 PM >>> To: si-list@xxxxxxxxxxxxx >>> Subject: [SI-LIST] ESD protectioin at a Digital Input >>> >>> Hi All, >>> >>> >>> I'm checking for ESD protection at a Digital Input pin. >>> >>> A Switch is connected to a Schmitt Buffer. The Schmitt buffer is ESD >>> rated >>> for 1000V HBM >>> >>> >>> >>> I'm planning to put an external suppressor for IEC levels, on the PCB >>> >>> My understanding is the clamping voltage should be less than the max >>> withstand capability of the pin to be protected. >>> >>> >>> >>> Since it has internal protection of 1000V, does that mean I can put a >>> suppressor with a clamping voltage of say 200V? >>> >>> >>> >>> Or should I use an ESD suppressor with a clamping voltage well below 10V? >>> >>> >>> >>> Regards >>> >>> >>> >>> Kumar >>> >>> >>> >>> >>> >>> ------------------------------------------------------------------ >>> 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 technical documents are available at: >>> http://www.si-list.net >>> >>> List archives are viewable at: >>> //www.freelists.org/archives/si-list >>> >>> Old (prior to June 6, 2001) list archives are viewable at: >>> http://www.qsl.net/wb6tpu >>> >>> DISCLAIMER: >>> ----------------------------------------------------------------------------------------------------------------------- >>> >>> The contents of this e-mail and any attachment(s) are confidential and >>> intended for the named recipient(s) only. >>> It shall not attach any liability on the originator or HCL or its >>> affiliates. Any views or opinions presented in >>> this email are solely those of the author and may not necessarily reflect >>> the opinions of HCL or its affiliates. >>> Any form of reproduction, dissemination, copying, disclosure, >>> modification, distribution and / or publication of >>> this message without the prior written consent of the author of this >>> e-mail is strictly prohibited. If you have >>> received this email in error please delete it and notify the sender >>> immediately. Before opening any mail and >>> attachments please check them for viruses and defect. >>> >>> ----------------------------------------------------------------------------------------------------------------------- >>> ------------------------------------------------------------------ >>> 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 technical documents are available at: >>> http://www.si-list.net >>> >>> List archives are viewable at: >>> //www.freelists.org/archives/si-list >>> >>> Old (prior to June 6, 2001) list archives are viewable at: >>> http://www.qsl.net/wb6tpu >>> >>> >>> >>> >>> >> -- >> ------------------------------------------------------- >> ___ _ Doug Smith >> \ / ) P.O. Box 1457 >> ========= Los Gatos, CA 95031-1457 >> _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 >> / /\ \ ] / /\ \ Mobile: 408-858-4528 >> | q-----( ) | o | Email: doug@xxxxxxxxxx >> \ _ / ] \ _ / Website: http://www.dsmith.org >> ------------------------------------------------------- >> >> ------------------------------------------------------------------ >> 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 technical documents are available at: >> http://www.si-list.net >> >> List archives are viewable at: >> //www.freelists.org/archives/si-list >> >> 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 technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > > 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 technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu