Beads sometimes get applied to front panel LEDs, switches and such in the belief that this will limit EMI radiation and/or ESD susceptibility. You can decide for yourself if you think, there is a lot that a ferrite bead is going to do that a 100-300 Ohm current limit resistor doesn't already do. Steve. z46147 wrote: > Content-type: text/plain; charset=gb2312 > Content-transfer-encoding: 7BIT > Hi all, > > I also want to know root cause of this application. > > Any thought on it would be appreciated. > > Best regards. > > Zhuyongfa > HUAWEI TECHNOLOGIES CO.,LTD. > > > Address: Huawei Industrial Base > Bantian Longgang > Shenzhen 518129, P.R.China > Tel:+86-755-89653025 > Fax: +86-755-89650731 > E-mail: zhuyongfa@xxxxxxxxxx > www.huawei.com > ------------------------------------------------------------------------------------------------------------------------------------- > This e-mail and its attachments contain confidential information from HUAWEI, > which > is intended only for the person or entity whose address is listed above. Any > use of the > information contained herein in any way (including, but not limited to, total > or partial > disclosure, reproduction, or dissemination) by persons other than the > intended > recipient(s) is prohibited. If you receive this e-mail in error, please > notify the sender by > phone or email immediately and delete it! > > ----- Original Message ----- > From: Vijay Anand > To: si-list@xxxxxxxxxxxxx > Sent: Tuesday, November 06, 2007 6:30 PM > Subject: [SI-LIST] LED with series bead > > > Dear All, > In our design we connect a bead in series with LED while driving from an > I/O pin. I dont know why this bead is connected ( still series resistor is > there for current limiting). Is there is any relation with EMI? Kindly do the > needful. > With Regards, > Vijay Anand. G > ------------------------------------------------------------------ > 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 > 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 > > > > > -- Binary/unsupported file stripped by Ecartis -- > -- Type: image/jpeg > -- File: outlook_huawei_logo_en.jpg > > > ------------------------------------------------------------------ > 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 > 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 > > > > > -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 California office (408) 884-3985 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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 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