On Sun, 23 Jul 2017 10:59:55 +0100, Kevin Aylward wrote:> That's the difference between board level and IC level. > > The more complex, the more you *must* simulate in asic design.Could you recommend a simulator that could handle this, Kev? ;)
LT spice, leakage inductance
Started by ●July 20, 2017
Reply by ●July 23, 20172017-07-23
Reply by ●July 23, 20172017-07-23
On 2017-07-22 16:47, krw@notreal.com wrote:> On Sat, 22 Jul 2017 12:01:43 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >> On Sat, 22 Jul 2017 11:40:34 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2017-07-22 07:43, John Larkin wrote: >> >> [snip] >>>> >>>> TPS54302 is a great little switcher, but I had to spend an afternoon >>>> breadboard fiddling to figure out all my needed compansations with >>>> various caps and voltages. I'll use a lot of them, so it was worth it. >>>> But neither TI's data sheet nor their software was much help. >>>> >>>> Colleges use LT Spice all over the world. It has its own culture. >>>> Culture matters. >>>> >>> >>> I'll second all that. 100%. >>> >>> I don't know how much sales I generated for LTC because of LTSpice but >>> it likely was 7-digit. And I am only one of many. >> >> Designed any chips with LTspice? > > Why would anyone even attempt such a thing? LTC doesn't sell fab > space. >Other people do :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●July 23, 20172017-07-23
On Sun, 23 Jul 2017 10:59:55 +0100, "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> wrote:>>"John Larkin" wrote in message >>news:a6b8nc9dhjv4f7qdfapt9ev6itr1l5vikl@4ax.com... > > > >>My systems are way too complex to simulate. I only sim one little >>section if I think there's any risk. > >That's the difference between board level and IC level. > >The more complex, the more you *must* simulate in asic design. > >Yes, they are different problems. I can change component values, reload ARM and FPGA code, replace parts, and blue-wire in a pinch. Or I can spin the whole thing in three weeks if I have to, which is rare these days. I can also change the specs, which you can do too. One of our boards can have several FPGAs (one has seven) one or two ARM CPUs (one has 13), several power supplies (or 22!), fiber optics, thermal stuff... no sane person would consider simulating the entire product. Actually, we spend at least 10x more engineering hours test-benching FPGAs as we spend on Spice sims. I remember in olden days when we did schematic design for an FPGA, didn't simulate at all, burned a OTP chip, and got it to work. The easier mistakes are to fix, the more mistakes there will be. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●July 23, 20172017-07-23
On 2017-07-22 17:05, krw@notreal.com wrote:> On Sat, 22 Jul 2017 12:43:48 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-07-22 12:05, Klaus Kragelund wrote:[...]>>> I have worked at 6 different firms and I have never come across any >>> colleagues using a single LT part. Only here at SED >>> >> >> In some markets a thorough simulation is very important. Most of my >> designs work quietly in the background somewhere. You may have had them >> very close to you, for example while flying in large aircraft. Others >> are in hospitals but those machines you'd only encounter after a serious >> cardiac event and hopefully that will never happen. > > I seem to have become a regular user of your sort of product. :-( >Intravascular diagnostics and ultrasound? As much as I like those machines I hope you soon won't need them anymore or at least not often. I am lucky, all my "plumbing" seems ok. It's the lower back that isn't. For years I had one blood test value that was out of whack but to my surprise that fell smack dab into the middle of the normal range after I begun intense bicycling. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●July 23, 20172017-07-23
On Sun, 23 Jul 2017 04:51:34 -0700 (PDT), klaus.kragelund@gmail.com wrote:>On Sunday, 23 July 2017 07:05:10 UTC+2, John Larkin wrote: >> On Sat, 22 Jul 2017 21:00:58 -0700, Jim Thompson >> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >> >On Sat, 22 Jul 2017 20:35:43 -0700, John Larkin >> ><jjlarkin@highlandtechnology.com> wrote: >> > >> >>On Sat, 22 Jul 2017 12:57:59 -0700, Jim Thompson >> >><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >> >> >>>On Sat, 22 Jul 2017 12:39:45 -0700, John Larkin >> >>><jjlarkin@highlandtechnology.com> wrote: >> >>> >> >>>>On Sat, 22 Jul 2017 12:11:44 -0700, Jim Thompson >> >>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: >> >>>> >> >>>>>On Sat, 22 Jul 2017 12:05:37 -0700 (PDT), Klaus Kragelund >> >>>>><klauskvik@hotmail.com> wrote: >> >>>>> >> >>>>>>On Saturday, July 22, 2017 at 8:40:24 PM UTC+2, Joerg wrote: >> >>>>>>> On 2017-07-22 07:43, John Larkin wrote: >> >>>>> >> >>>>>[snip] >> >>>>>>> > >> >>>>>>> > Colleges use LT Spice all over the world. It has its own culture. >> >>>>>>> > Culture matters. >> >>>>>>> > >> >>>>>>> >> >>>>>>> I'll second all that. 100%. >> >>>>>>> >> >>>>>>> I don't know how much sales I generated for LTC because of LTSpice but >> >>>>>>> it likely was 7-digit. And I am only one of many. >> >>>>>>> >> >>>>>>I don't believe that for a second >> >>>>>> >> >>>>>>I have worked at 6 different firms and I have never come across any colleagues using a single LT part. Only here at SED >> >>>>>> >> >>>>>>Cheers >> >>>>>> >> >>>>>>Klaus >> >>>>> >> >>>>> {>:-} >> >>>>> >> >>>>>Right down there with Microchip Analog parts ;-) >> >>>>> >> >>>>> ...Jim Thompson >> >>>> >> >>>>Some of their parts are quite good, like their comparators. >> >>> >> >>>[Begin personal opinion (legal disclaimer) mode ;-] >> >>> >> >>>Their Spice models are the suckiest of the sucky. >> >>> >> >>> ...Jim Thompson >> >> >> >>Who needs a Spice model for a comparator? I sure don't. >> > >> >You apparently only do _one_device_at_a_time_ simulations? >> > >> >No whole-system simulations? >> > >> > ...Jim Thompson >> >> My systems are way too complex to simulate. I only sim one little >> section if I think there's any risk. Lots of products don't need >> simulation at all; design it, lay out the board, and sell it. For a >> complex product, I can do that sooner than someone could sim it. >> > >"Way to complex to simulate"? > >I think you meant to say you don't want to spend the time to simulate your systems?Time and money. The statements are almost equivalent. With an army of engineers and programmers and scientists, I guess you could simulate an entire system, down to component level. And ship it in 5 years or so.> >We routinely do complete system simulations, cross discliplinary ones, mixing motors, power electronics and even C-code)And FPGAs?> >What is complex to simulate is radiated EMC, we have not done that yet, but it's in the pipelineIs that worth it?> >Cheers > >Klaus-- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●July 23, 20172017-07-23
On Sun, 23 Jul 2017 04:47:28 -0700 (PDT), klaus.kragelund@gmail.com wrote:>On Sunday, 23 July 2017 02:01:51 UTC+2, k...@notreal.com wrote: >> On Sat, 22 Jul 2017 12:05:37 -0700 (PDT), Klaus Kragelund >> <klauskvik@hotmail.com> wrote: >> >> >On Saturday, July 22, 2017 at 8:40:24 PM UTC+2, Joerg wrote: >> >> On 2017-07-22 07:43, John Larkin wrote: >> >> > On Sat, 22 Jul 2017 08:42:45 +0100, "Kevin Aylward" >> >> > <kevinRemovAT@kevinaylward.co.uk> wrote: >> >> > >> >> >> "John Larkin" wrote in message >> >> >> news:2r95nc5ls1rrm7cmp5ptn26kmlrroi6jpp@4ax.com... >> >> >> >> >> >> On Fri, 21 Jul 2017 21:25:00 +0100, "Kevin Aylward" >> >> >> <kevinRemovAT@kevinaylward.co.uk> wrote: >> >> >> >> >> >>> "John Larkin" wrote in message >> >> >>> news:m794nclodso7tu7c9bihmic1cuqtuf4ufa@4ax.com... >> >> >>> >> >> >>> >> >> >>> >> >> >>>> Companies buy companies because the bought companies are eating >> >> >>>>> onto the buying companies revenues. The buying company wants the, now get >> >> >>>>> this, the *Customers* of the bought company, and secondly, their >> >> >>>>> *products* >> >> >>>>> that customers *buy*. LT gets billions of revenue from paying customers, >> >> >>>>> that's what ADI want and bought. Dah.... >> >> >>>>> >> >> >>>>> LTSpice is just a nice icing on the cake sort of thing. If it ceased to >> >> >>>>> exist, it ut bwould make F'all difference. That's reality. >> >> >>> >> >> >>>> It's a major sales tool. >> >> >>> >> >> >>> No. Its a sales tool. >> >> >>> >> >> >>>> People pay for sales tools. >> >> >>> >> >> >>> Sure, but not $1B. >> >> >>> >> >> >>>> When I made the suggestion to the LT/ADI transition team, nobody >> >> >>>> contradicted me. I'd guess that LT Spice added at least a billion >> >> >>>> dollars to the deal. >> >> >>> >> >> >>>> Complete and utter nonsense. >> >> >>> >> >> >>>> Like, Cadence do about $2B revenue. Candace is THE mainstream de-facto >> >> >>>> system in IC design. You know, the things that the world runs on. >> >> >>> >> >> >>>> You're trying to claim that the LT Freebee is on a par in value. >> >> >>> >> >> >>>> LT do about $2B in physical sales. You are effectively trying to claim >> >> >>>> that >> >> >>>> if LTSpice didn't exist, LT would lose like $100Ms of dollars. Bullshit. >> >> >>> >> >> >>>> You really need to stand back and think about the big picture. >> >> >>> >> >> >>>> People buy LT parts because of the performance, not because of a >> >> >>>> simulater. >> >> >>>> Period. >> >> >>> >> >> >>>> LTSpice only has to improve sales by say, a million or so to justify its >> >> >>>> existence, i.e Mike's salary :-). I agree, it probably does that, and such >> >> >>>> a >> >> >>>> salary pisses me off no end.... >> >> >>>> >> >> >> >> >> >>> In summary, you are jealous of LT Spice and its author. >> >> >> >> >> >> The summary, is that some here have absolutely no idea whatsoever of the >> >> >> value of some marketing tools. >> >> >> >> >> >> AD do about $3B in product. >> >> >> >> >> >> How much would it cost to for any company to get the Spice3 code, and hire >> >> >> someone to write a GUI for it? Like a few $100k ? >> >> >> >> >> >> Hint: you can buy 3rd party GUI tools that have schematic capture as a drop >> >> >> in component. >> >> >> >> >> >> Do your really think all the other companies are so totally stupid that they >> >> >> wouldn't invest a few hundred $ to produce a full featured Spice to give >> >> >> away for free if it would net them a $1B more a year in revenue. Get real. >> >> >> >> >> >> >> >> >> -- Kevin Aylward >> >> >> http://www.anasoft.co.uk - SuperSpice >> >> >> http://www.kevinaylward.co.uk/ee/index.html >> >> > >> >> > ADI paid 14.8 big ones for LTC. LTC charges at least 2x what other >> >> > people charge for similar functions. LT Spice helps them do that. >> >> > >> >> > TI's sim stuff won't even run on my PC for some reason. So I use LTC >> >> > parts unless the cost impact is extreme. >> >> > >> >> > TPS54302 is a great little switcher, but I had to spend an afternoon >> >> > breadboard fiddling to figure out all my needed compansations with >> >> > various caps and voltages. I'll use a lot of them, so it was worth it. >> >> > But neither TI's data sheet nor their software was much help. >> >> > >> >> > Colleges use LT Spice all over the world. It has its own culture. >> >> > Culture matters. >> >> > >> >> >> >> I'll second all that. 100%. >> >> >> >> I don't know how much sales I generated for LTC because of LTSpice but >> >> it likely was 7-digit. And I am only one of many. >> >> >> >I don't believe that for a second >> > >> >I have worked at 6 different firms and I have never come across any colleagues using a single LT part. Only here at SED >> >> So you're saying that LT doesn't actually sell parts in the $Bs? Or >> are you saying that everyone who uses those $Bs worth of LT parts is >> here on SED? >> >I am saying that no-one I know of in the real world (if SED is not a real world) uses LT parts and I know several hundreds HW designers > >The wild claim that LTspice would spawn 7 digit generated extra sales is totally unsupported and sounds like something Trump could say, or not even him, like 100 times Trump.Not annual parts sales, but sales price of LTC to ADI. If I had meant parts sales, I would have specified a timebase, as in "annual" or "accumulated" or something. I talked to an LTC-ADI transition team, and they agreed that LT Spice mattered in the acquisition. So, one billion added out of 15 is not a wild claim. I'd guess more. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●July 23, 20172017-07-23
On Sun, 23 Jul 2017 10:59:47 +0100, "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> wrote:>>"John Larkin" wrote in message >>news:1887ncd3ck4rgg6981vbat3hm6b3l7u18v@4ax.com... > > >>> >>> TPS54302 is a great little switcher, but I had to spend an afternoon >>> breadboard fiddling to figure out all my needed compansations with >>> various caps and voltages. I'll use a lot of them, so it was worth it. >>> But neither TI's data sheet nor their software was much help. >>> >>> Colleges use LT Spice all over the world. It has its own culture. >>> Culture matters. >>> >> >>I'll second all that. 100%. >> >>I don't know how much sales I generated for LTC because of LTSpice but >>it likely was 7-digit. And I am only one of many. > >>Literally millions of kids will get EE degrees where they learned to >>use LT Spice. LTS has mediocre documentation and HELP, and lots of >>hidden features, and the best tutorials are written by college profs, >>for their students. All those kids will go out and continue to use LT >>Spice, and spec LTC parts. [1] [2] > >So what? > >If the analysis was correct that such marketing resulted in Billions of >extra sales, ALL the other vendors would be doing the same. The cost of >producing a new Berkley/XSpice GUI spice is trivial.TI has Tina and Webench. ADI has... something. They are trying to do what LTC has done, and are doing it badly. ADI now owns LT Spice.> >TI is not blooody stupid. They do $10B in sales. They know that giving out a >total free spice, whilst useful, isn't that useful. Parts are bought on >availability, performance and cost. End of.I want my boards to work first time. Good, easy to use sim tools sell me parts. TI doesn't have good sim tools.> >The number od competent analog users of spice is probably < 10,000 if even >that, anyway. Only a tiny fraction of those LT users will ever go on to be >pro designers influencing parts purchasing. Assuming that selection will >weed out most of the shit ones, the remaining better ones will presumably be >rationally selecting parts from all the vendors, not because they were >bribed.As I said, I want things to work first time. Spinning a design is a heap more expensive than the differential cost of a serial DAC.> >>They won't be using SuperSpice much, because the student version is >>badly crippled and not free. > >What I will say here is that, you have no idea as what what I actually do >when someone orders a Student version :-)Buy a six-pack? -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●July 23, 20172017-07-23
On 2017-07-23 04:47, klaus.kragelund@gmail.com wrote:> On Sunday, 23 July 2017 02:01:51 UTC+2, k...@notreal.com wrote: >> On Sat, 22 Jul 2017 12:05:37 -0700 (PDT), Klaus Kragelund >> <klauskvik@hotmail.com> wrote: >> >>> On Saturday, July 22, 2017 at 8:40:24 PM UTC+2, Joerg wrote: >>>> On 2017-07-22 07:43, John Larkin wrote: >>>>> On Sat, 22 Jul 2017 08:42:45 +0100, "Kevin Aylward" >>>>> <kevinRemovAT@kevinaylward.co.uk> wrote: >>>>> >>>>>> "John Larkin" wrote in message >>>>>> news:2r95nc5ls1rrm7cmp5ptn26kmlrroi6jpp@4ax.com... >>>>>> >>>>>> On Fri, 21 Jul 2017 21:25:00 +0100, "Kevin Aylward" >>>>>> <kevinRemovAT@kevinaylward.co.uk> wrote: >>>>>> >>>>>>> "John Larkin" wrote in message >>>>>>> news:m794nclodso7tu7c9bihmic1cuqtuf4ufa@4ax.com... >>>>>>> >>>>>>> >>>>>>> >>>>>>>> Companies buy companies because the bought companies >>>>>>>> are eating >>>>>>>>> onto the buying companies revenues. The buying >>>>>>>>> company wants the, now get this, the *Customers* of >>>>>>>>> the bought company, and secondly, their *products* >>>>>>>>> that customers *buy*. LT gets billions of revenue >>>>>>>>> from paying customers, that's what ADI want and >>>>>>>>> bought. Dah.... >>>>>>>>> >>>>>>>>> LTSpice is just a nice icing on the cake sort of >>>>>>>>> thing. If it ceased to exist, it ut bwould make F'all >>>>>>>>> difference. That's reality. >>>>>>> >>>>>>>> It's a major sales tool. >>>>>>> >>>>>>> No. Its a sales tool. >>>>>>> >>>>>>>> People pay for sales tools. >>>>>>> >>>>>>> Sure, but not $1B. >>>>>>> >>>>>>>> When I made the suggestion to the LT/ADI transition >>>>>>>> team, nobody contradicted me. I'd guess that LT Spice >>>>>>>> added at least a billion dollars to the deal. >>>>>>> >>>>>>>> Complete and utter nonsense. >>>>>>> >>>>>>>> Like, Cadence do about $2B revenue. Candace is THE >>>>>>>> mainstream de-facto system in IC design. You know, the >>>>>>>> things that the world runs on. >>>>>>> >>>>>>>> You're trying to claim that the LT Freebee is on a par >>>>>>>> in value. >>>>>>> >>>>>>>> LT do about $2B in physical sales. You are effectively >>>>>>>> trying to claim that if LTSpice didn't exist, LT would >>>>>>>> lose like $100Ms of dollars. Bullshit. >>>>>>> >>>>>>>> You really need to stand back and think about the big >>>>>>>> picture. >>>>>>> >>>>>>>> People buy LT parts because of the performance, not >>>>>>>> because of a simulater. Period. >>>>>>> >>>>>>>> LTSpice only has to improve sales by say, a million or >>>>>>>> so to justify its existence, i.e Mike's salary :-). I >>>>>>>> agree, it probably does that, and such a salary pisses >>>>>>>> me off no end.... >>>>>>>> >>>>>> >>>>>>> In summary, you are jealous of LT Spice and its author. >>>>>> >>>>>> The summary, is that some here have absolutely no idea >>>>>> whatsoever of the value of some marketing tools. >>>>>> >>>>>> AD do about $3B in product. >>>>>> >>>>>> How much would it cost to for any company to get the Spice3 >>>>>> code, and hire someone to write a GUI for it? Like a few >>>>>> $100k ? >>>>>> >>>>>> Hint: you can buy 3rd party GUI tools that have schematic >>>>>> capture as a drop in component. >>>>>> >>>>>> Do your really think all the other companies are so totally >>>>>> stupid that they wouldn't invest a few hundred $ to produce >>>>>> a full featured Spice to give away for free if it would net >>>>>> them a $1B more a year in revenue. Get real. >>>>>> >>>>>> >>>>>> -- Kevin Aylward http://www.anasoft.co.uk - SuperSpice >>>>>> http://www.kevinaylward.co.uk/ee/index.html >>>>> >>>>> ADI paid 14.8 big ones for LTC. LTC charges at least 2x what >>>>> other people charge for similar functions. LT Spice helps >>>>> them do that. >>>>> >>>>> TI's sim stuff won't even run on my PC for some reason. So I >>>>> use LTC parts unless the cost impact is extreme. >>>>> >>>>> TPS54302 is a great little switcher, but I had to spend an >>>>> afternoon breadboard fiddling to figure out all my needed >>>>> compansations with various caps and voltages. I'll use a lot >>>>> of them, so it was worth it. But neither TI's data sheet nor >>>>> their software was much help. >>>>> >>>>> Colleges use LT Spice all over the world. It has its own >>>>> culture. Culture matters. >>>>> >>>> >>>> I'll second all that. 100%. >>>> >>>> I don't know how much sales I generated for LTC because of >>>> LTSpice but it likely was 7-digit. And I am only one of many. >>>> >>> I don't believe that for a second >>> >>> I have worked at 6 different firms and I have never come across >>> any colleagues using a single LT part. Only here at SED >> >> So you're saying that LT doesn't actually sell parts in the $Bs? >> Or are you saying that everyone who uses those $Bs worth of LT >> parts is here on SED? >> > I am saying that no-one I know of in the real world (if SED is not a > real world) uses LT parts and I know several hundreds HW designers >Drop into the Zeitgeist pub next time you are in S.F. Chances are you'll meet John Larkin and some of his engineers. Then you'd know HW designers who use lots of LTC parts. And they've got really good beer there. I recommend Anchor Steam OBA.> The wild claim that LTspice would spawn 7 digit generated extra sales > is totally unsupported and sounds like something Trump could say, or > not even him, like 100 times Trump. >Obviously I can't reveal details but I developed a circuit around a PFC-capable chip from LTC that enabled me to do something that hasn't been done before (and was considered impossible) because it allowed direct access to the internal modulator. This is in mass production now, regardless of the fact that each chip costs above $2. Because it's worth it and makes the client money. Then there was a boost converter chip that I used in very unorthodox ways because LTSpice lets me simulate driving it via the compensator pin. I discovered a shortcoming on that chip, had a chat with the guys at LTC about it and ... shortly thereafter an A version came out with that issue fixed. Try that with another manufacturer.> Proof it by looking at the 2001 1 billion rise in sales that should > be visible in the financial statement (it was 2001 when Switchercad > became LTspice, right) >Hey, 7-digit is not 1 billion :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●July 23, 20172017-07-23
On 2017-07-22 20:42, John Larkin wrote:> On Sat, 22 Jul 2017 12:50:57 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-07-22 12:16, John Larkin wrote:[...]>> >>> [2] NI understands this dynamic too. When I was a kid, I worked >>> summers in a college electronics lab, for 85 cents an hour. Fairchild >>> and TI would send us boxes of their newfangled silicon transistors; >>> same idea. >>> >> >> Oh yeah. I have yet to encounter a client where their test lab is not >> running on NI modules and LabView. At one we needed to switch some >> higher voltage and a simple relay board cost hundreds of Dollars. > > Yesterday one of my customers was complaining about critical NI > modules, used in their test stands, going EOL. They are scouring ebay > for more. >Excellent opportunity to present a new Highland Technology module that can replace it, if you guys have the time :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●July 23, 20172017-07-23
On 2017-07-23 04:54, klaus.kragelund@gmail.com wrote:> On Sunday, 23 July 2017 13:27:02 UTC+2, Tim Williams wrote: >> "Joerg" <news@analogconsultants.com> wrote in message >> news:ethokiFlh4dU1@mid.individual.net... >>> >>> Sometimes I have to design mission-critical stuff. There cost is >>> secondary but you have to simulate the dickens out of it. That is >>> not possible when using an IC for which no SPICE model is >>> published. >>> >> >> Wait a sec... >> >> Where the hell do you find SPICE models that are /approved for >> mission critical analysis/?! >> >> You're lucky if they put any confidence into their models at all >> ("this model as-is only" or what have you)... >It is much better than not being able to simulate at all like it is with many chips from other companies.> We use both Saber, PSpice and LTspice (LTspice only 2 guys) > > I was involved in modelling of a LTspice, and we found plenty of > differences from the analog world to the simulation. I never trust a > simulation without a measurement > > Some agencies, will allow it. We have done simulation that UL > approved, but very simple ones that can be checked for accuracy >Yup, simulation alone won't fly. But it is often needed, especially for "what if" scenarios. Though mainly to show the margins and to corroborate the derating calculations. -- Regards, Joerg http://www.analogconsultants.com/
