Re: Input voltage range - EN61000-4, 5 and 6
I read in !emc-pstc that brent.dew...@us.datex-ohmeda.com wrote (in ) about 'Input voltage range - EN61000-4, 5 and 6', on Thu, 18 Apr 2002: >In the very specific case of Medical devices, the newest edition of IEC >60601-1-2 specifies -5 testing at the extreme ends the range of >continuously adaptive supply and in each range of a switched range supply. That should be reserved for safety testing, for which it is justified. I think it's gilding the lily for EMC. We are measuring with great precision, using exhaustive (and exhausting!) test protocols, quantities that bear only a very approximate relation to the actual EMC performance in any given real-life condition. Thus, these costly measurements have to be accompanied by a disclaimer that they do not guarantee freedom from unacceptable interference and further measures may be required in some cases. AFAIK, apart from the 60601 case, for EMC testing the rated supply voltage (or one of them) is applied. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Agency mark dims
Good People I have not been able to find any requirements on the TUV or UL websites for minimum size requirements of their respective logos (when used as a safety mark on the recognized/certified product). Could someone provide a pointer to (agency-published) guidance for logo dims? Thanks Much, Brian O'Connell Taiyo Yuden (USA), Inc. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Suitable CDN for IEC61000-4-6 ethernet 10/100
Most people use the EM clamp. We test to EN50130-4 alarm system limits: 10V, pulsed and AM modulated. The test is trivial because of the inherent immunity of Ethernet; be sure you understand the EUT and AE port partitioning algorithms. Constructing a CDN that compliant to ANSI/IEEE 802.3/802.3u twisted pair transmission line definitions for 10BaseT and 100BaseTX is not trivial. When you play games with the transmission line the Ethernet/F-E link becomes 'cable-length sensitive', i.e. less S/N at certain cable lengths ... confounding the immunity test results. It is probably possible to design an Ethernet/F-E CDN, I would want correlation data before using it. EN55022:1998 RF-conducted emissions test methods for UTP Ethernet are controversial; I prefer to discuss them off-line. David Sterner ADEMCO, Syosset, NY -Original Message- From: Carpentier Kristiaan [mailto:carpenti...@thmulti.com] Sent: Thursday, April 18, 2002 2:05 PM To: emc-p...@majordomo.ieee.org Subject: Suitable CDN for IEC61000-4-6 ethernet 10/100 Hello group, IEC 61000-4-6 mentions a decision chart on the use of injection method: 1rst question of this chart: are suitable CDN's available? if YES: use CDN as per 6.2.2 if NO: use other means (e.g. EM Clamp) My question: 1. Are CDN's used for CE in EN55022 "suitable" CDN's for ethernet 10/100BaseT? (like ENY22 of R&S) I might assume these CDN will at least attenuate the ethernet signal and thus make the signal more sensitive to the AM coupled signal 2. Assumed the CDN is suitable, is it allowed to use an alternative method like EM Clamp anyway? As usual, many thanks for your valuable responses Regards, Kris Carpentier --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
IATA 902 Magnetic Testing
Although this is not an EMC standard it is related. My lab has been asked to test our products to the magnetic standards of IATA Packing Instruction 902. This test determines the ability of a device to change a compass reading. I have the regulations and know how to do the test, but do not do it routinely. Products that fail this test must be labeled and additional shipping charges are imposed. I know that one of our products fails and we are labeling it. Fines for non-compliance are substantial, yet I am having a hard time finding anyone who knows about or complies with this standard. My questions are: Does anyone else perform this test, or have it performed on their products? What kind of results are you getting depending upon product size, shape, metal content? Are there exceptions or conditions that would exclude product families from this regulation. Any help or discussion would be appreciated. Bud Pittman Compliance Engineer LSI Logic Storage Systems, Inc. - Wichita KS bud.pitt...@lsil.com Tel 316-636-8718 Fax 316-636-8321
Re: Input voltage range - EN61000-4, 5 and 6
In the very specific case of Medical devices, the newest edition of IEC 60601-1-2 specifies -5 testing at the extreme ends the range of continuously adaptive supply and in each range of a switched range supply. Regards, Brent DeWitt gunter_j_ma...@embraco.com.br@majordomo.ieee.org on 04/18/2002 12:25:38 PM Please respond to gunter_j_ma...@embraco.com.br Sent by: owner-emc-p...@majordomo.ieee.org To: emc-p...@majordomo.ieee.org cc: Subject: Input voltage range - EN61000-4, 5 and 6 List I suppose that EN61000-4-4, 4-5 and 4-6 do not mention the input voltage to be applied to the EUT during the tests. For a product with a voltage range, like 198 up to 264Vac (230Vac nominal), what should be the right value ? Or do I need to look for the worst voltage case ? Thank you for your time. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Obtaining Lab Accreditation
Hello Group, I have been tasked with obtaining A2LA accreditation for my internal (first party) lab. We have about ten technicians, perform all standard suite of IEC EMC tests along with vibration, shock, bump and environmental (cold, dry heat, damp heat) testing. I have attended ISO 17025 training but still have some questions. I'm wondering if there is anyone out there who has experience with ISO 17025 of ISO Guide 25 lab accreditation who can answer these questions: 1. Roughly how long did it take you to obtain the accreditation start to finish? I am thinking that it will take about one year. 2. Would you mind sharing the contents of your Quality Manual? 3. Is there a group or organization around that one could obtain example Quality Manuals from? 4. What were some of the benefits and reasons for obtaining lab accreditation? Was it worth while and why? Thanks for your input. Don -- This e-mail may contain SEL confidential information. The opinions expressed are not necessarily those of SEL. Any unauthorized disclosure, distribution or other use is prohibited. If you received this e-mail in error, please notify the sender, permanently delete it, and destroy any printout. Thank you. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Decoupling - capacitor values
I am not advocating placing an inductor in series with the cap. Circulating loop currents in the power and ground traces will create emissions, but those currents can be reduced by use of bypass capacitors or an L-type filter (capacitor and inductor) in the 5V trace. At least, according to accepted theory. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: Thursday, April 18, 2002 11:57 AM To: emc-p...@majordomo.ieee.org Subject: RE: Decoupling - capacitor values Not sure this would be a cure in this instance. This is effectively the same as adding a lossy inductor in series with the cap, which would tend to negate any benefits of using a cap with lower self inductance. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: April 18, 2002 4:57 AM To: emc-p...@majordomo.ieee.org Subject: RE: Decoupling - capacitor values Consider adding a ferrite bead in the 5V trace to the microprocessor. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Wednesday, April 17, 2002 4:50 PM To: emc-p...@majordomo.ieee.org Subject: Decoupling - capacitor values A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeep
Magnetic Testing
Although this is not an EMC standard it is related. My lab has been asked to test our products to the magnetic standards of IATA Packing Instruction 902. This test determines the ability of a device to change a compass reading. I have the regulations and know how to do the test, but do not do it routinely. Products that fail this test must be labeled and additional shipping charges are imposed. I know that one of our products fails and we are labeling it. Fines for non-compliance are substantial, yet I am having a hard time finding anyone who knows about or complies with this standard. My questions are: Does anyone else perform this test, or have it performed on their products? What kind of results are you getting depending upon product size, shape, metal content? Are there exceptions or conditions that would exclude product families from this regulation. Any help or discussion would be appreciated. Bud Pittman Compliance Engineer LSI Logic Storage Systems, Inc. - Wichita KS bud.pitt...@lsil.com Tel 316-636-8718 Fax 316-636-8321
Suitable CDN for IEC61000-4-6 ethernet 10/100
Hello group, IEC 61000-4-6 mentions a decision chart on the use of injection method: 1rst question of this chart: are suitable CDN's available? if YES: use CDN as per 6.2.2 if NO: use other means (e.g. EM Clamp) My question: 1. Are CDN's used for CE in EN55022 "suitable" CDN's for ethernet 10/100BaseT? (like ENY22 of R&S) I might assume these CDN will at least attenuate the ethernet signal and thus make the signal more sensitive to the AM coupled signal 2. Assumed the CDN is suitable, is it allowed to use an alternative method like EM Clamp anyway? As usual, many thanks for your valuable responses Regards, Kris Carpentier --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Input voltage range - EN61000-4, 5 and 6
List I suppose that EN61000-4-4, 4-5 and 4-6 do not mention the input voltage to be applied to the EUT during the tests. For a product with a voltage range, like 198 up to 264Vac (230Vac nominal), what should be the right value ? Or do I need to look for the worst voltage case ? Thank you for your time. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: SV: Decoupling - capacitor values
Amund, I have encountered similar problems with similarly designed boards. In one interesting case, I was able to get 30 dB reduction in radiated EMI by adding a series resistor to a (fairly short) low-frequency clock line. Due to use of modern devices, its rise and fall times were less than a nanosecond. The resistor limits current in the trace, reducing also the power required of the clock driver, and slows the slew rate. Improving power distribution also made a large difference; power and ground planes were added to the board and also improved signal integrity. But I prefer to first attack problems such as yours with better decoupling. One all-nighter long ago resulted in my soldering SMD capacitors directly across pins on a device package, 1208 for the pins farther from grounds, and 805's for ones closer to grounds. This made a considerable difference but was greeted by my boss with, "YOU DID WHAT?!" It DID open him up to the possibility of less drastic measures previously ruled out. The suggestions you've been given about power routing are on target. If you distribute power and its return as a transmission line themselves, you can at least control where noise on it goes, reducing THAT loop size, and filters on this line may be expected to work predictably. However, do remember that once you put noise on silicon, it gets onto everything else. You must satisfy the need for current at each device: enough capacitance, able to supply current quickly enough, at enough power and ground pin pairs. If you allow device Vcc/ground to be periodically modulated by device switching current, the noise produced will be present on every trace leaving the device and you will not make it go away. That's why I first look for good decoupling when doing schematic and layout reviews. THEN I look for routing missteps and inadvertent loops. Others may prefer to approach things in a different order; that's just my preference. But it works for me. Good luck! Cortland Richmond --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Decoupling - capacitor values
Not sure this would be a cure in this instance. This is effectively the same as adding a lossy inductor in series with the cap, which would tend to negate any benefits of using a cap with lower self inductance. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: April 18, 2002 4:57 AM To: emc-p...@majordomo.ieee.org Subject: RE: Decoupling - capacitor values Consider adding a ferrite bead in the 5V trace to the microprocessor. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Wednesday, April 17, 2002 4:50 PM To: emc-p...@majordomo.ieee.org Subject: Decoupling - capacitor values A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Decoupling - capacitor values
Years ago in ultrasonic echocardiography instrumentation (the ultrasonics analog is a wide band receiver listening in the 1-10MHz region down to less than 10uV, so the digital had better be quiet!) which used a bit slice architecture system containing Schottky logic with a clock of 20MHz for controlling and manipulating images in real time. We're talking 4 PCBs using 10 amps each board, so you can see the opportunity for generating horrific noise that would be injected into the analog section. We found that power distributed using a "tree" type of distribution where traces were thick then thinner out at the extremities *and* +5 was over top of GND made for the quietest distribution. The tree technique worked much quieter than the "recommended" grid structure where +5 distribution on bottom layer goes one direction with GND distribution on the top going the other. This structure made little tiny loop antennas that radiated energy all around inside the box and was awful! But easier for the layout people. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: am...@westin-emission.no To: ieee pstc list List-Post: emc-pstc@listserv.ieee.org Date: Thursday, April 18, 2002 12:49 AM Subject: SV: Decoupling - capacitor values > >Correct, the picture is complex. The PCB is 2-layer with signal, 5V-power >and 0V-ref lines routed on both sides. There is no ground layer/plane. There >must be a large number of RF current loops because the 0V-lines are routed >up and down and around. >Beside trying to achieve a good decoupling I assume that reducing loop area >is the most important. > >Amund > > > >-Opprinnelig melding- >Fra: Cortland Richmond [mailto:72146@compuserve.com] >Sendt: 18. april 2002 00:54 >Til: am...@westin-emission.no; ieee pstc list >Emne: Re: Decoupling - capacitor values > > >Yes, it makes sense. But the goal here is preventing or reducing Vcc drop >during the time the microprocessor is switching. You need not only low >reactance, but *also* enough capacitance to supply the current needed >_while it is switching_. You have not given enough information here to tell >if 820pF is sufficient. > >Regards, > >Cortland Richmond > >Amund Westin wrote: > >>> Insert a SMD ceramic capacitor of value 820pF in parallel with the >existing >100nF. The reason for the low value 820pF is because the capacitor >self-resonance frequency is approximate 180MHz, and I believe it is >important to choose a Cap value with a resonance frequency higher than the >frequency we would like to decouple. > >Does it make sense? > ><< > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Question concerning antenna carousels, their usefulness, credibility ofdata collected, and......
Hi, I have not used a carousel and would not do so without a lot of data to show that it dose not affect antenna behavior. It has been shown that the terminal impedance of an antenna changes as it is moved up from 1m above the ground plane. Similarly, at 3m, it is possible for the presence of a table top product with a power cord dropping to the ground plane to affect the antenna impedance. So anything close(r) to my antenna would be a problem for me. Remember the goal of any measurement technique is that the measurement should not affect the data and for us the object be measured should not re-calibrate the measurement device (antenna). The effects described above are only 1 or 2 dB and only at low or specific frequencies. However a closer spacing would increase this. Some studies I have done recently looked at bringing a cable close to the apertures in a shield showed emission increases of up to 12db - now this was a very close spacing 10 cm or so, but the coupling mechanism is there. In CISPR 25 you refer to the spacing from the walls of the ANECHOIC chamber. These walls are nominally non reflecting, an antenna is reflective and will have some very frequency dependent characteristics that will change with location (height). So I believe the coupling would be hard to predict or measure but would add "a few dB" to the uncertainty of your measured data. This would be mostly a low frequency problem where one of the antennas is not very directional. Back to back logs might be fine, but with a log bicon pair the bicon would se the log as a parasitic element (two element, poorly designed yagi). For a quick preliminary scan this might be a perfect solution but for high accuracy measurements I doubt it. My 2c, Colin.. Et Al: I am soliciting opinions from anyone who has attempted using an antenna carousel that aids in doing automated EMI measurements under CISPR 25. The CISPR 25 specification provides requirements in terms of spacings of the antenna elements from the walls of the room, size of the room, use of anechoic material, etc but not pertaining to adjacent antennas. In addition, certain automotive companies place further requirements in terms of expected performance relative to Round Robin results of a Test Artifact taken at several labs before allowing a new lab to be listed as AEMCLRP accredited. I look forward to hearing from those involved in the Automotive Industry who have information either good/bad relating to this issue. Regards, Jeffrey W. Greilich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Decoupling - capacitor values
Amund, That is why I wrote that the leads should hug close to the microprocessor package. Sort of like a piggy back, that way the lead loop inductance is at the minimum, since I guess correctly that the Vcc and Gnd pins are miles apart. I suppose it is not a mass production model, so it is acceptable to 'piggy back' the 100 pF decoupling cap across the microprocessor. I am assuming that the existing 'bulky' capacitor will take care of the voltage stabilizing requirement. In fact, 100 pF may too large under some circumstances and you are left with the option of splicing the Vcc and ground tracks (assuming they are running in parallel) and insert in a pair of surface mounted inductor to act like a common mode filter. Like what I did in my thesis all those years ago. I had a 20dB reduction in radiated emission in the 180MHz to 300+ MHz band, just by introducing a pair of inductors to isolate the battery from the rest of the test circuit. The details of the layout is published in Chapter 5, page 81-83. My apologies, the site is a bit erratic and on my last try (just a min ago) has been temporarily put out of action, probably due to heavy traffic. http://www.geocities.com/timfoo6143 :-) Tim Foo amund@westin-emission. no To: , <[mailto:f...@np.edu.sg]> Sent by: cc: (bcc: Wan Juang Foo/ece/staff/npnet) owner-emc-pstc@majordo Subject: SV: Decoupling - capacitor values mo.ieee.org 04/18/02 04:53 PM Please respond to amund Interesting articles on your web-site, Tim. >BTW, how about just using a 100 pF capacitor with the 'leads' hugging close >to the microprocessor package There's a "mile" from the Vcc pin to ground, that's another problem. No ground plane, only ground traces which is routed around on the PCB. This product is soon leaving this world (it's an old product), but we are trying to let it exits a few more months before a new version is released. New emission requirements (24dBuV/m @ 3m, freq.band 155MHz-165MHz) might let it die very soon --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Question concerning antenna carousels, their usefulness, credibility of data collected, and......
Jeffrey, You are correct. The standards do not address the usage of multiple antennas. We have not participated in any Round Robin testing multiple antennas in the test chamber, so I am not exactly sure what the possible effects would be in terms of getting accurate and/or repeatable results. >From my experience, I would guess that any object in an absorption chamber that does not absorb, will affect things like repeatability, and uncertainty in your measurements. It would be another question to ask just how much? and is it worth considering? Best Regards, Scott Mee Johnson Controls Inc. Automotive Systems Group EMC Product Compliance 616.394.2565 scott@jci.com |-+-> | | Jeff.Greilich@asl-tk.c| | | om| | | Sent by: | | | owner-emc-pstc@majordo| | | mo.ieee.org | | | | | | | | | 04/16/02 02:15 PM | | | Please respond to | | | Jeff.Greilich | | | | |-+-> >--| | | |To: emc-p...@ieee.org | |cc: | |Subject: Question concerning antenna carousels, their usefulness, credibility of data collected, and..| >--| Et Al: I am soliciting opinions from anyone who has attempted using an antenna carousel that aids in doing automated EMI measurements under CISPR 25. The CISPR 25 specification provides requirements in terms of spacings of the antenna elements from the walls of the room, size of the room, use of anechoic material, etc but not pertaining to adjacent antennas. In addition, certain automotive companies place further requirements in terms of expected performance relative to Round Robin results of a Test Artifact taken at several labs before allowing a new lab to be listed as AEMCLRP accredited. I look forward to hearing from those involved in the Automotive Industry who have information either good/bad relating to this issue. Regards, Jeffrey W. Greilich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Decoupling - capacitor values
Hmmm. I've read a couple of other replies on this...good suggestions. I have also read your re-replies which suggest that you have a two layer "planeless" board. I understand that you are trying to get an unwanted 156Mhz off of the 5V line. A couple of thoughts come to mind. First 156Mhz would need quite a long radiator to radiate efficiently. 156Mhz is approximately a 2m wavelength. One tenth of this wavelength is still 20cm. Why does this matter? Well, I like the decoupling cap idea. Another suggestion might be to add a large bulk decoupling cap such as a 10uF tantalum (you may have to experiment with the value) right at the chip. Then cut the 5V trace (on the other side of this cap) and put a good, strong ferrite (I like PREM SPG-104's myself) in the 5V trace. The bulk cap will serve as a local bulk storage device, the ferrite will help to isolate the harmonics to the area immediately around the processor. If you can keep the harmonics within a small area, perhaps they won't radiate very effectively andmaybe your product can live for another few months. Here's hoping that you find a solution. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | > -Original Message- > From: am...@westin-emission.no [SMTP:am...@westin-emission.no] > Sent: Wednesday, April 17, 2002 4:50 PM > To: emc-p...@majordomo.ieee.org > Subject: Decoupling - capacitor values > > > A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is > decoupled by > a 100nF capacitor with a few mm leads. We can observe an unwanted > 156MHz > signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to > suppress/decouple this 156MHz signal. > > Suggestion: > Insert a SMD ceramic capacitor of value 820pF in parallel with the > existing > 100nF. The reason for the low value 820pF is because the capacitor > self-resonance frequency is approximate 180MHz, and I believe it is > important to choose a Cap value with a resonance frequency higher than > the > frequency we would like to decouple. > > Does it make sense? > > Best regards > Amund Westin, Oslo/Norway > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Decoupling - capacitor values
Consider adding a ferrite bead in the 5V trace to the microprocessor. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Wednesday, April 17, 2002 4:50 PM To: emc-p...@majordomo.ieee.org Subject: Decoupling - capacitor values A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Decoupling - capacitor values
I read in !emc-pstc that Robert Wilson wrote (in <3FF57405336C9B4C976A1819F860A2560F696F@xng_tirsys.TIRSYS.COM>) about 'Decoupling - capacitor values', on Wed, 17 Apr 2002: >The main >reason is that the ESR of the larger cap begins to rise to unacceptable >levels as frequency rises (chiefly due to its self inductance). ESR is something quite separate from self-inductance. The effect of the inductance is to *reduce* the total impedance of the capacitor to just the ESR at the self-resonance frequency and to *increase* it above that frequency. The ESR may itself be frequency-dependent because it includes dielectric losses (in the simple CRL series model of the capacitor). -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
SV: Decoupling - capacitor values
Interesting articles on your web-site, Tim. >BTW, how about just using a 100 pF capacitor with the 'leads' hugging close >to the microprocessor package There's a "mile" from the Vcc pin to ground, that's another problem. No ground plane, only ground traces which is routed around on the PCB. This product is soon leaving this world (it's an old product), but we are trying to let it exits a few more months before a new version is released. New emission requirements (24dBuV/m @ 3m, freq.band 155MHz-165MHz) might let it die very soon Amund -Opprinnelig melding- Fra: Wan Juang Foo [mailto:f...@np.edu.sg] Sendt: 18. april 2002 10:01 Til: am...@westin-emission.no; emc-p...@majordomo.ieee.org Emne: Re: Decoupling - capacitor values Amund, In the absence of any layout information that can evaluate the loop inductances, I suggest you read what I wrote about placing two capacitor in parallel which can be found on Chapter 3 of my thesis. A link is available in: http://www.geocities.com/timfoo6143/index.html BTW, how about just using a 100 pF capacitor with the 'leads' hugging close to the microprocessor package. i.e. assuming you are using a leaded capacitor (on say a QFP). :-) Tim Foo --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: Decoupling - capacitor values
Amund, In the absence of any layout information that can evaluate the loop inductances, I suggest you read what I wrote about placing two capacitor in parallel which can be found on Chapter 3 of my thesis. A link is available in: http://www.geocities.com/timfoo6143/index.html BTW, how about just using a 100 pF capacitor with the 'leads' hugging close to the microprocessor package. i.e. assuming you are using a leaded capacitor (on say a QFP). :-) Tim Foo amund@westin-emission. no To: Sent by: cc: (bcc: Wan Juang Foo/ece/staff/npnet) owner-emc-pstc@majordo Subject: Decoupling - capacitor values mo.ieee.org 04/18/02 04:49 AM Please respond to amund A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Northeast Product Safety Society Meeting on Wednesday, April 24
There will be a Northeast Product Safety Society meeting on Wednesday, April 24, at EMC Corporation's Customer Briefing Center in Hopkinton, MA. A social hour with light refreshments will begin at 7:00 PM and the technical meeting will start at 7:30 PM. James Norton, CEO of EMD Optima, will be presenting this months technical topic concerning requirements and techniques for machine guarding and safety. The presentation will include national and international safety standards, compliance considerations, common liability questions, safety systems documentation and essential training requirements, and new ANSI requirements for steps to take to reduce potential risk. For further information about this meeting and Mr. Norton please see the NPSS website at http://www.nepss.org/meetings/next-mtgapr.html. The 2002 NPSS meeting schedule is available on the NPSS website at http://www.nepss.org/about/npss2002kf.html. The President's March message is available on the NPSS website at http://www.nepss.org/messagefrompresident/messagepres_030502.html. Further information about the Northeast Product Safety Society and how to become a member is available at http://www.nepss.org. You can also contact one of the NPSS officers via links at http://www.nepss.org/about/officerskf.html. Directions: >From Route 495 North or South take exit 21B to South Street. At the first traffic light, turn left (Note: This is on South direction side of Route 495). EMC Corporation is the second driveway on the right. Matt Campanella NPSS Secretary Compliance Engineer Motorola, Inc. Broadband Communications Sector 3 Highwood Drive East Tewksbury, MA 01876 (978) 858-2303 Direct (978) 858-2300 Main (978) 858-2399 Fax matthew.campane...@motorola.com email --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
SV: Decoupling - capacitor values
Correct, the picture is complex. The PCB is 2-layer with signal, 5V-power and 0V-ref lines routed on both sides. There is no ground layer/plane. There must be a large number of RF current loops because the 0V-lines are routed up and down and around. Beside trying to achieve a good decoupling I assume that reducing loop area is the most important. Amund -Opprinnelig melding- Fra: Cortland Richmond [mailto:72146@compuserve.com] Sendt: 18. april 2002 00:54 Til: am...@westin-emission.no; ieee pstc list Emne: Re: Decoupling - capacitor values Yes, it makes sense. But the goal here is preventing or reducing Vcc drop during the time the microprocessor is switching. You need not only low reactance, but *also* enough capacitance to supply the current needed _while it is switching_. You have not given enough information here to tell if 820pF is sufficient. Regards, Cortland Richmond Amund Westin wrote: >> Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? << --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
