Re: Shrunk-die power MOSFET's and compliance
I worked with power MOSFETs in the past and found that the reverse recovery characteristics (soft versus abrupt) correlated with emissions, but we could not derive a quantitative acceptance criteria. Vendors could easily specify and sort by reverse recovery time, but that was a different parameter, and was inadequately related to emisions levels. Technically the best solution was to test and approve FETs by batch number, based on the measured emissions of a sample product. "Cook, Jack" wrote: > > The practice of die shrinking & speedups causes problems in the digital IC > arena also. The old but once heavily used 8051 processor is an example. > Original designs were with the NMOS (HMOS?) version but later began being > replaced by faster CMOS versions. We could see some of that clearly in > certain product audits. > > Jack Cook, > Xerox EMC Engineering > > -Original Message- > From: Dan Kwok [mailto:dk...@intetron.com] > Sent: Thursday, October 25, 2001 1:16 PM > To: Jim Eichner; 'EMC-PSTC - forum' > Subject: Re: Shrunk-die power MOSFET's and compliance > > Jim, > > You have my sympathies. Some manufacturers don't seem to realize that their > so called product "improvements" may actually cause undue grief and > hardships > on their customers. "Specifications subject to change without notice" is a > common catch clause associated with far many products on the market these > days. > > In one company where I worked many years ago, we had an incoming inspection > department that routinely carried out random samplings and measured critical > parameters for crystals and semiconductors. With this approach, most > out-of-spec devices simply did not make it to the store bins. > > On the brighter side, speeding up a FET is hard to do. Slowing it down in a > circuit is much easier for EMC purposes. > > - > Dan Kwok, P.Eng. > Principal Engineer > Electromagnetic Compatibility > Intetron Consulting, Inc. > Ph (604) 432-9874 > E-mail dk...@intetron.com > Internet http://www.intetron.com > > ----- Original Message - > From: "Jim Eichner" > To: ; "Jim Eichner" ; > "'EMC-PSTC - forum'" > Sent: Wednesday, October 24, 2001 11:54 AM > Subject: RE: Shrunk-die power MOSFET's and compliance > > > > > Well for example, I have just finished specifying what compliance > re-testing > > I am going to need to do on 4 different products whose power conversion > > stages use IRF630's, IRF740's, IRF840's, and RFP50N06's, but the list goes > > on and on. If you are using power FET's in power electronics, chances are > > they have changed or will soon. The main manufacturers that come to mind > > are IR, Fairchild/Harris, Philips, and STM-Thomson. Not all have forced > > changes to the shrunk-die version - some have agreed to keep the old style > > available - and all have at least added a suffix to their markings on the > > devices so you can tell if it's the new revision die or old. In one case, > > however, we received modified parts with no markings differentiating them > > from the old rev parts, for almost a year with no communication from the > mfr > > telling us about the change. We found out through other channels and then > > contacted them. They seem to be behaving as if fundamental changes to the > > performance and specifications of the part are none of our business. > > > > I am re-doing radiated and conducted emissions, some thermal testing, and > a > > bunch of functional testing and looking at waveforms on 4 different > products > > affected by this change. Those are only the products I am responsible > for - > > as a company we're doing functional testing and possibly compliance > > re-testing on many more products. > > > > This is not a simple component substitution exercise, if your products are > > or use power electronics! I would advise everyone potentially affected to > > have your procurement department look into this. > > > > Regards, > > Jim Eichner, P.Eng. > > Manager, Engineering Services > > Xantrex Technology Inc. > > Mobile Power > > web: www.xantrex.com <http://www.xantrex.com> > > Any opinions expressed are those of my invisible friend, who really > > exists. Honest. > > > > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site
RE: Shrunk-die power MOSFET's and compliance
The practice of die shrinking & speedups causes problems in the digital IC arena also. The old but once heavily used 8051 processor is an example. Original designs were with the NMOS (HMOS?) version but later began being replaced by faster CMOS versions. We could see some of that clearly in certain product audits. Jack Cook, Xerox EMC Engineering -Original Message- From: Dan Kwok [mailto:dk...@intetron.com] Sent: Thursday, October 25, 2001 1:16 PM To: Jim Eichner; 'EMC-PSTC - forum' Subject: Re: Shrunk-die power MOSFET's and compliance Jim, You have my sympathies. Some manufacturers don't seem to realize that their so called product "improvements" may actually cause undue grief and hardships on their customers. "Specifications subject to change without notice" is a common catch clause associated with far many products on the market these days. In one company where I worked many years ago, we had an incoming inspection department that routinely carried out random samplings and measured critical parameters for crystals and semiconductors. With this approach, most out-of-spec devices simply did not make it to the store bins. On the brighter side, speeding up a FET is hard to do. Slowing it down in a circuit is much easier for EMC purposes. - Dan Kwok, P.Eng. Principal Engineer Electromagnetic Compatibility Intetron Consulting, Inc. Ph (604) 432-9874 E-mail dk...@intetron.com Internet http://www.intetron.com - Original Message - From: "Jim Eichner" To: ; "Jim Eichner" ; "'EMC-PSTC - forum'" Sent: Wednesday, October 24, 2001 11:54 AM Subject: RE: Shrunk-die power MOSFET's and compliance > > Well for example, I have just finished specifying what compliance re-testing > I am going to need to do on 4 different products whose power conversion > stages use IRF630's, IRF740's, IRF840's, and RFP50N06's, but the list goes > on and on. If you are using power FET's in power electronics, chances are > they have changed or will soon. The main manufacturers that come to mind > are IR, Fairchild/Harris, Philips, and STM-Thomson. Not all have forced > changes to the shrunk-die version - some have agreed to keep the old style > available - and all have at least added a suffix to their markings on the > devices so you can tell if it's the new revision die or old. In one case, > however, we received modified parts with no markings differentiating them > from the old rev parts, for almost a year with no communication from the mfr > telling us about the change. We found out through other channels and then > contacted them. They seem to be behaving as if fundamental changes to the > performance and specifications of the part are none of our business. > > I am re-doing radiated and conducted emissions, some thermal testing, and a > bunch of functional testing and looking at waveforms on 4 different products > affected by this change. Those are only the products I am responsible for - > as a company we're doing functional testing and possibly compliance > re-testing on many more products. > > This is not a simple component substitution exercise, if your products are > or use power electronics! I would advise everyone potentially affected to > have your procurement department look into this. > > Regards, > Jim Eichner, P.Eng. > Manager, Engineering Services > Xantrex Technology Inc. > Mobile Power > web: www.xantrex.com <http://www.xantrex.com> > Any opinions expressed are those of my invisible friend, who really > exists. Honest. > > > --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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
Re: Shrunk-die power MOSFET's and compliance
Jim, You have my sympathies. Some manufacturers don't seem to realize that their so called product "improvements" may actually cause undue grief and hardships on their customers. "Specifications subject to change without notice" is a common catch clause associated with far many products on the market these days. In one company where I worked many years ago, we had an incoming inspection department that routinely carried out random samplings and measured critical parameters for crystals and semiconductors. With this approach, most out-of-spec devices simply did not make it to the store bins. On the brighter side, speeding up a FET is hard to do. Slowing it down in a circuit is much easier for EMC purposes. - Dan Kwok, P.Eng. Principal Engineer Electromagnetic Compatibility Intetron Consulting, Inc. Ph (604) 432-9874 E-mail dk...@intetron.com Internet http://www.intetron.com - Original Message - From: "Jim Eichner" To: ; "Jim Eichner" ; "'EMC-PSTC - forum'" Sent: Wednesday, October 24, 2001 11:54 AM Subject: RE: Shrunk-die power MOSFET's and compliance > > Well for example, I have just finished specifying what compliance re-testing > I am going to need to do on 4 different products whose power conversion > stages use IRF630's, IRF740's, IRF840's, and RFP50N06's, but the list goes > on and on. If you are using power FET's in power electronics, chances are > they have changed or will soon. The main manufacturers that come to mind > are IR, Fairchild/Harris, Philips, and STM-Thomson. Not all have forced > changes to the shrunk-die version - some have agreed to keep the old style > available - and all have at least added a suffix to their markings on the > devices so you can tell if it's the new revision die or old. In one case, > however, we received modified parts with no markings differentiating them > from the old rev parts, for almost a year with no communication from the mfr > telling us about the change. We found out through other channels and then > contacted them. They seem to be behaving as if fundamental changes to the > performance and specifications of the part are none of our business. > > I am re-doing radiated and conducted emissions, some thermal testing, and a > bunch of functional testing and looking at waveforms on 4 different products > affected by this change. Those are only the products I am responsible for - > as a company we're doing functional testing and possibly compliance > re-testing on many more products. > > This is not a simple component substitution exercise, if your products are > or use power electronics! I would advise everyone potentially affected to > have your procurement department look into this. > > Regards, > Jim Eichner, P.Eng. > Manager, Engineering Services > Xantrex Technology Inc. > Mobile Power > web: www.xantrex.com <http://www.xantrex.com> > Any opinions expressed are those of my invisible friend, who really > exists. Honest. > > > --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Shrunk-die power MOSFET's and compliance
Well for example, I have just finished specifying what compliance re-testing I am going to need to do on 4 different products whose power conversion stages use IRF630's, IRF740's, IRF840's, and RFP50N06's, but the list goes on and on. If you are using power FET's in power electronics, chances are they have changed or will soon. The main manufacturers that come to mind are IR, Fairchild/Harris, Philips, and STM-Thomson. Not all have forced changes to the shrunk-die version - some have agreed to keep the old style available - and all have at least added a suffix to their markings on the devices so you can tell if it's the new revision die or old. In one case, however, we received modified parts with no markings differentiating them from the old rev parts, for almost a year with no communication from the mfr telling us about the change. We found out through other channels and then contacted them. They seem to be behaving as if fundamental changes to the performance and specifications of the part are none of our business. I am re-doing radiated and conducted emissions, some thermal testing, and a bunch of functional testing and looking at waveforms on 4 different products affected by this change. Those are only the products I am responsible for - as a company we're doing functional testing and possibly compliance re-testing on many more products. This is not a simple component substitution exercise, if your products are or use power electronics! I would advise everyone potentially affected to have your procurement department look into this. Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com <http://www.xantrex.com> Any opinions expressed are those of my invisible friend, who really exists. Honest. -Original Message- From: Michael Mertinooke [mailto:mertino...@skyskan.com] Sent: Wednesday, October 24, 2001 6:45 AM To: 'Jim Eichner' Subject: RE: Shrunk-die power MOSFET's and compliance Jim; I suspect that a lot of us just don't have time to investigate the latest subtleties involved in producing a new chip design sold under an old component part number. We order by manufacturer part number and when the order comes in we count the pieces and throw it in the stockroom. If there are reliability problems, most companies take a month or so for the news to get back from Field Service. Then the issue goes to Manufacturing because we know the design worked perfectly for X years, so Manufacturing must have built 'em wrong, or the PC house had a bad batch of boards or somebody screwed up the wave solder machine again or the stockroom was sweeping parts off the floor and dumping them back in the bins ... or a hundred other cockups that happen every day. By the time somebody finally figures out that the FETs are not performing as they should, it could be a year after the parts first hit the receiving dock. Instead of a general reference, perhaps you can provide a few part numbers? If I see such a list and my FETs are on it, then I sure as hell am going to look into it immediately! Thanks. Mike Mertinooke --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Shrunk-die power MOSFET's and compliance
No takers? I haven't had any responses, but I can't believe that ins't an issue for many of you. The switch-mode power supplies used in almost all equipment these days are the main users of these FET's, and the FET design change does effect compliance. Have none of you run into this issue? Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com -Original Message- From: Jim Eichner [mailto:jim.eich...@xantrex.com] Sent: Wednesday, October 17, 2001 5:11 PM To: 'EMC-PSTC - forum' Subject: Shrunk-die power MOSFET's and compliance I'm curious what others in the compliance community have experienced over the last year or so in regards to re-designed power MOSFET's that the big FET manufacturers are pushing on us. These next generation "trench" style FET's have smaller dies, resulting in lower on-resistance but higher thermal impedance to their cases, and in lower gate capacitances and faster rise times. At first glance it seems obvious these changes could impact the compliance of power conversion products in the areas of emissions (increase due to faster rise times), susceptibility to surges, and perhaps temperatures (not that agencies care about FET temperatures, but if they're hotter neighbouring components may be too). The FET's involved are some of the highest volume parts these mfr's make (to achieve maximum savings), and are widely used in power electronics. Since most products either are, use, or contain power electronics these days, I'd expect this issue to be affecting almost all of us. I'd be glad to hear of any experiences the forum has had with this issue. Thanks, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com Any opinions expressed are those of my invisible friend, who really exists. Honest. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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: No longer online until our new server is brought online and the old messages are imported into the new server.
