On Monday, May 25, 2020 at 9:05:28 AM UTC+10, Cydrome Leader wrote:> Bill Sloman <bill.sloman@ieee.org> wrote: > > On Sunday, May 24, 2020 at 4:54:41 AM UTC+10, Cydrome Leader wrote: > >> Bill Sloman <bill.sloman@ieee.org> wrote: > >> > On Saturday, May 23, 2020 at 5:32:38 PM UTC+10, Cydrome Leader wrote: > >> >> Klaus Kragelund <klauskvik@hotmail.com> wrote: > >> >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: > >> >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs > >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> >> > >> >> >> >On 2020-05-21 13:38, John Larkin wrote: > >> >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs > >> >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> >> >> > >> >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: > >> >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> >> >> >>>> > >> >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: > >> >> >> >>>>>> > >> >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >> >> >>>>>>>> > >> >> >> >>>>>>>> It's an ST1L08. > >> >> >> >>>>>>>> > >> >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? > >> >> >> >>>>>>> > >> >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >> >> >>>>>> > >> >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts > >> >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to > >> >> >> >>>>>> milliohms of Rds-on. > >> >> >> >>>>>> > >> >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >> >> >>>>>>> > >> >> >> >>>>>> > >> >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much > >> >> >> >>>>>> current to run a couple DRAM chips. > >> >> >> >>>>>> > >> >> >> >>>>> > >> >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >> >> >>>>> with 3% tolerance. As usual with products originating in the > >> >> >> >>>>> East, the datasheet is rather sparse about details, but I've used > >> >> >> >>>>> them and they do what I want. > >> >> >> >>>> > >> >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> >> >> >>>> > >> >> >> >>>> We need so many goofy voltages that we usually buy adjustable > >> >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel > >> >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx > >> >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> >> >> >>>> > >> >> >> >>>>> > >> >> >> >>>>>> You sure are in a bad mood lately. > >> >> >> >>>>>> > >> >> >> >>>>> I've noticed that lately with some regulars here, including a few > >> >> >> >>>>> who normally exhibit decent manners. > >> >> >> >>>> > >> >> >> >>>> Well, some never show any sign of manners. They are repulsive but > >> >> >> >>>> you've got to feel sorry for them, stuck being around themselves all > >> >> >> >>>> day. > >> >> >> >>>> > >> >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and > >> >> >> >>>> designing electronics. > >> >> >> >>> > >> >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( > >> >> >> >>> > >> >> >> >>> He was a bit of a statistical outlier. > >> >> >> >> > >> >> >> >> He was crabby and dismissive of people not as smart as he was, and > >> >> >> >> hostile to people that might have been smarter, but he was > >> >> >> >> occasionally helpful, and had a sense of humor, and was very brave at > >> >> >> >> the end. > >> >> >> > > >> >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, > >> >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on > >> >> >> >some deserving individuals. ;) > >> >> >> > >> >> >> Gosh, nobody's perfect. > >> > > >> > He was imperfect enough to look remarkably like a psychopath. > >> > > >> >> >> >He was probably nice enough in person--we collaborated a couple of times > >> >> >> >but never met in person or even talked on the phone together. > >> >> >> > > >> >> >> >I agree that he had guts and seems to have died very well. > >> >> >> > >> >> >> I used a version of his clever CD ignition (without his permission) as > >> >> >> a gain-switched laser driver. Nice circuit. > >> >> >> > >> >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more > >> >> > > >> >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it > >> >> > > >> >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point > >> >> > > >> >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip > >> >> > >> >> Got to ask here, if I didn't years ago. How much different in behavior are > >> >> analog circuits laid out with discrete components from the final IC > >> >> itself? > >> > > >> > My impression is integrated circuit designs don't look much like discrete component designs. > >> > > >> > Lot's more current sources, and many fewer resistors for a start. At high frequencies, the fact that the connections are lot shorter (and less inductive) makes a big difference. Bob Widlar and Barry Gilbert were famously good at exploiting the advantages these sorts of difference offer. > >> > > >> >> Let's talk pre computer simulations. For example, microwave and RF > >> >> boards are constructed different from audio circuit boards, but if you > >> >> look at a schematic, it's just a bunch of discretes wired together. > >> > > >> > If you look at the printed circuit boards, microwave and RF boards are > >> > constructed with the critical connections laid out as constant impedance > >> > transmission lines routed over (or between) solid ground planes (mostly > >> > buried in multilayer boards). Buried ground planes do show up in some > >> > audio circuits - they do a good job of shielding sensitive bits from > >> > noise radiated from the higher current bits, and any digital signals > >> > running around - but you can get by without them. > >> > > >> > Looking at the schematic isn't all that educational - essentially it's a > >> > way of representing the net-list (which pins on which components are > >> > connected to which other pins). It leaves out stray capacitances, lead > >> > inductances, mutual inductances between leads, heat dissipation, > >> > component dimensions and the rest of the stuff that constrains printed > >> > circuit layout. > >> > >> so how did they come up with designs that worked? Take the first op amps > >> for example. The behavior of the silicon isn't going to match a breadboard > >> with some parts on it. Was it just a completely iterative process back in > >> the day to get anything to work? > >> > >> > Back when I was designing circuits, the schematic got passed to the > >> > drafting shop with several pages of notes on how it was going to have to > >> > be laid out. > >> > > >> > The good layout draftsmen didn't need much, but they weren't all good. > >> > Once a printed circuit manufacturer didn't like my board stack-up - they > >> > feared that the board would warp - and the draftsman okayed their > >> > version. > >> > > >> > A whole lot of constant impedance transmission ended up with with the > >> > wrong impedance. It took us a couple weeks to wake up. > >> > >> Was any of this salvagable, or was it on to rev b? > > > > It got sort of cobbled into sort of working with lot's of sub-minature Filotex coaxial cable (about 1.1 mm OD IIRR). The other thing that messed up the board was Gigabit Logic's failure to put the input capacitance of their logic on the data sheet - on rev b every last clock input had it's own private driver. > > > > The other thing that messed it up was that it was supposed to clock a long 100k ECL synchronous counter at 200MHz, which would have been doable with careful design - as I had spelled out in the specification. The guy who did the detailed design of the board was entirely capable of managing that, but was also smart enough to know that the machine was never going to get into production - it didn't - and didn't bother. > > > > If we'd done a design review on the schematic before releasing for printed circuit layout I might well have caught it, but our idiot project manager didn't want to slow down the process by the day that would have taken. > > > > We had a similar drop-off on the digital signal process board which took much longer to find (but was much easier to cope with when it did get noticed). > > > > I was sufficiently peeved by the time the project got cancelled - after three years work when the machine was working - to take away three years worth of weekly reports. About fifteen years later I got around to scanning them. > > > > You could read them here > > > > http://sophia-elektronica.com/At_Cambridge.html > > Interesting read- nearly completed with 1989. Got some more observations > questions, if you don't mind. > > How were low production SMD boards populated back then? Semi-manual or > automated?Semi-manual. We never got enough boards made that the people who loaded them would have automated the placement. I got fairly close to that - these were the first surface mount boards used a Cambridge Instruments - and Iened up being responsible for getting the tools we needed - which was mainly a Groatmoor hot air reworking tool, which I'd seen at every service mount shop that I'd visited.> The references to 17A -5.2v ECL boards was amusing too. I was reading > somewhere that some folks didn't use conventional regulated power supplies > for ECL boards as the load never changed. Is there any truth to this?No. We bought our supplies off the shelf, and they were perfectly conventional switching power supplies, if reasonably quiet.> What were the special mu-metal tanks and covers for?No idea.> The 0.4Hz cursor update speed on a display is funny, in comparison for the > hunt for 100ps timing on other parts of the device.Delivering information to a human observer can take advantage of the relative slowness of the human comprehension system where it's taking up complicated information.> There was reference to some type of glue logic (7400 series?) LS vs HC > where the HC series stuff used too much power. Wasn't the CMOS stuff > supposed to be lower power, or was this only below certain frequencies? I > recall some other boards where the power hungry "S" series stuff was still > used in place of LS series parts.When we wanted speed we went for ECL and GaAs. Most of the rest of the machine was upgraded - as little and as cheaply as possible - from original Lintech electron beam tester. We did go for the AMD Taxichip links for high volume data transfer - and put minimal galvanic isolation into the links to minimise ground loop problems.> > if you were a glutton for punishment. The reports are accessible > - in > > one year chunks - at the bottom of the page. There's also a link there > > to a document that fills in some of the immediate background. > > > > It will make more sense if your read my "short history of voltage > > contrast" link at the top of the page, which ends with links to same set > > of documents. > > > >> Anyone have stories of most expensive screw ups with board design or > >> assemble? > > > > I think we were paid about a thousand UK pounds for the board that got > > screwed up - it was a six layer board, with the two outer layers made of > > isocyanate bonded Teflon (PTFE) cloth, rather than than the standard > > epoxy-bonded glass fibre. The printed circuit house had had to buy in an > > expensive chunk of the PTFE based board material before they could make > > the board, and didn't expect to sell any of it to anybody else. > > I wonder what the board houses yield was, 0.008" traces is still pretty > small. How large were these boards? The AMD 0.1% yield on another > component was pretty funny too. There was an issue at work where a process > (not product) had a 5% pass rate. My joke was the systems that passed > validation were simply done right, by accident.It was an up-market board house, and they didn't have any trouble with the layout design rules. In fact they probably prescribed them. Printed circuit layout was done by specialist draftsmen and some of our was done by a specialist sub-contractor, but the engineers got to sit with the draft's person to sort out the more demanding bits of the boards. Given the chance, I would have reviewed every last board layout before we sent it off to get etched, but our idiot project manager didn't want to delay the process by delaying sending it out for that.> > We then stuck about five hundred UK pounds worth of GaAs integrated > > circuits from GigaBit Logic onto the board. That meant that we'd spent > > more than two thousand US dollars on the board. It was a triple extended > > Eurocard, which was pretty big for a rack-mounted board plugging into a > > backplane. > > OK, so triple extended euro card was the size of the fancy board? Need to > look that up. > > How hard would all this be to contruct using modern technology? I find it > fascinating that we still fall back to plain silicon and don't require > exotic materials for speeds you were dealing with.Quite a lot easier. Most of the logic could have been squeezed into programmable logic parts. I did a detailed design on a similar sort of system at Nijmegen University around 1997, and the programmable parts we could buy then still weren't fast enough for the fastest bits but did allow us to squeezed down the data handling area quite a lot. We used a lot of 22V10 programmable parts in 1989, and even then we could have done better, but it would have meant chucking out existing designs. The ICT Place ICT7024 was a drop-in replacement for the 22V10 but a good deal more powerful, but I didn't get use one until 1991 when I was wording for another company.> Is this simply because components can be made smaller now? The spec sheets > for USB3 transceivers have many values in uS and even nS, way faster than > even fancy chips back then. They're plain old silicon and work fine on > even crappy circuit boards, and cost nothing. It's quite amazing.The AMD Taxichip was a long step along the road to USB, and we were really very happy to have something that could run a serial link at 125MHz. USB-C would have put us in the seventh heaven. Motorola were starting to push ECLinPS back in 1990 (and one of their chips does get mentioned in one of my later weekly reports) but you couldn't buy them then. By the time I'd got to Niimegen - at the end of 1993 - ECLinPS was stocked by major distributors , and I used some of the parts to upgrade an old electron spin resonance machine, and was planning to use quite a few more in the new version that got designed but never built. -- Bill Sloman, Sydney
why do they do this?
Started by ●May 18, 2020
Reply by ●May 25, 20202020-05-25
Reply by ●May 25, 20202020-05-25
On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote:> Klaus Kragelund <klauskvik@hotmail.com> wrote: > > On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: > >> Klaus Kragelund <klauskvik@hotmail.com> wrote: > >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: > >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs > >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> > >> >> >On 2020-05-21 13:38, John Larkin wrote: > >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs > >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> >> >> > >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: > >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >> >> >>>> > >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: > >> >> >>>>>> > >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >> >> >>>>>>>> > >> >> >>>>>>>> It's an ST1L08. > >> >> >>>>>>>> > >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? > >> >> >>>>>>> > >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >> >> >>>>>> > >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts > >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp > >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to > >> >> >>>>>> milliohms of Rds-on. > >> >> >>>>>> > >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >> >> >>>>>>> > >> >> >>>>>> > >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much > >> >> >>>>>> current to run a couple DRAM chips. > >> >> >>>>>> > >> >> >>>>> > >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V > >> >> >>>>> with 3% tolerance. As usual with products originating in the > >> >> >>>>> East, the datasheet is rather sparse about details, but I've used > >> >> >>>>> them and they do what I want. > >> >> >>>> > >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >> >> >>>> > >> >> >>>> We need so many goofy voltages that we usually buy adjustable > >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel > >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx > >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. > >> >> >>>> > >> >> >>>>> > >> >> >>>>>> You sure are in a bad mood lately. > >> >> >>>>>> > >> >> >>>>> I've noticed that lately with some regulars here, including a few > >> >> >>>>> who normally exhibit decent manners. > >> >> >>>> > >> >> >>>> Well, some never show any sign of manners. They are repulsive but > >> >> >>>> you've got to feel sorry for them, stuck being around themselves all > >> >> >>>> day. > >> >> >>>> > >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and > >> >> >>>> designing electronics. > >> >> >>> > >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( > >> >> >>> > >> >> >>> He was a bit of a statistical outlier. > >> >> >> > >> >> >> He was crabby and dismissive of people not as smart as he was, and > >> >> >> hostile to people that might have been smarter, but he was > >> >> >> occasionally helpful, and had a sense of humor, and was very brave at > >> >> >> the end. > >> >> >> > >> >> > > >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, > >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on > >> >> >some deserving individuals. ;) > >> >> > >> >> Gosh, nobody's perfect. > >> >> > >> >> > > >> >> >He was probably nice enough in person--we collaborated a couple of times > >> >> >but never met in person or even talked on the phone together. > >> >> > > >> >> >I agree that he had guts and seems to have died very well. > >> >> > >> >> I used a version of his clever CD ignition (without his permission) as > >> >> a gain-switched laser driver. Nice circuit. > >> >> > >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more > >> > > >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it > >> > > >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point > >> > > >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip > >> > > >> > Cheers > >> > > >> > Klaus > >> > >> Got to ask here, if I didn't years ago. How much different in behavior are > >> analog circuits layed out with discrete components from the final IC > >> itself? Let's talk pre computer simulations. For example, microwave and RF > >> boards are constructed different from audio circuit boards, but if you > >> look at a schematic, it's just a bunch of discretes wired together. > > > > It can be very simelar > > > > In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors > > > > The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. > > > > If you wander off, and do custom blocks, it gets a lot more expensive > > > > So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design > > If not, simulations is the way forward > > > > And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in > > > > > > Cheers > > > > Klaus > > Hmm. What about equivalent, full sized components? > > Take the example the 74LS00 nand gate, TI has a schematic > > https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html > > Are there equivalent transistors and diodes used in that schematic I can > run out and buy, to make an as close to 100% electrically compatible, drop > in replacement? > > I'm not even sure what the first transitor is with A and B inputs is even > called. What is it?Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. -- Bill Sloman, Sydney
Reply by ●May 25, 20202020-05-25
On 2020-05-24, Cydrome Leader <presence@MUNGEpanix.com> wrote:> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >>> Klaus Kragelund <klauskvik@hotmail.com> wrote: > > Hmm. What about equivalent, full sized components? > > Take the example the 74LS00 nand gate, TI has a schematic > > https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html > > Are there equivalent transistors and diodes used in that schematic I can > run out and buy, to make an as close to 100% electrically compatible, drop > in replacement?you'll get similar behaviour, speed may differ some.> I'm not even sure what the first transitor is with A and B inputs is even > called. What is it?The '00 and 'S00 have a dual emitter transistors - unobtanium, but you can fake one just parallel two regular transistors but seperate the emitters. The 'S00 and 'LS00 make extensitve use of Schottky transistors these are just regular transistors with Schottky diodes from base to collector. -- Jasen.
Reply by ●May 25, 20202020-05-25
On 25.5.20 07:28, Bill Sloman wrote:> On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote: >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>> On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >>>> Klaus Kragelund <klauskvik@hotmail.com> wrote: >>>>> On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >>>>>> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> On 2020-05-21 13:38, John Larkin wrote: >>>>>>>> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>> >>>>>>>>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >>>>>>>>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >>>>>>>>>> >>>>>>>>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >>>>>>>>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >>>>>>>>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >>>>>>>>>>>> >>>>>>>>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >>>>>>>>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >>>>>>>>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >>>>>>>>>>>>>> >>>>>>>>>>>>>> It's an ST1L08. >>>>>>>>>>>>>> >>>>>>>>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >>>>>>>>>>>>> >>>>>>>>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >>>>>>>>>>>> >>>>>>>>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >>>>>>>>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >>>>>>>>>>>> from some higher voltage and over-drive an nfet follower down to >>>>>>>>>>>> milliohms of Rds-on. >>>>>>>>>>>> >>>>>>>>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >>>>>>>>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >>>>>>>>>>>> current to run a couple DRAM chips. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >>>>>>>>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >>>>>>>>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >>>>>>>>>>> with 3% tolerance. As usual with products originating in the >>>>>>>>>>> East, the datasheet is rather sparse about details, but I've used >>>>>>>>>>> them and they do what I want. >>>>>>>>>> >>>>>>>>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >>>>>>>>>> >>>>>>>>>> We need so many goofy voltages that we usually buy adjustable >>>>>>>>>> regulators for stock. The board that I'm doing now has a 24-channel >>>>>>>>>> analog mux to BIST the power supplies, using the dreadful Xilinx >>>>>>>>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> You sure are in a bad mood lately. >>>>>>>>>>>> >>>>>>>>>>> I've noticed that lately with some regulars here, including a few >>>>>>>>>>> who normally exhibit decent manners. >>>>>>>>>> >>>>>>>>>> Well, some never show any sign of manners. They are repulsive but >>>>>>>>>> you've got to feel sorry for them, stuck being around themselves all >>>>>>>>>> day. >>>>>>>>>> >>>>>>>>>> There's a basically perfect -1 correlation between being obnoxious and >>>>>>>>>> designing electronics. >>>>>>>>> >>>>>>>>> Well, now that Jim Thompson is apparently no longer with us. :( >>>>>>>>> >>>>>>>>> He was a bit of a statistical outlier. >>>>>>>> >>>>>>>> He was crabby and dismissive of people not as smart as he was, and >>>>>>>> hostile to people that might have been smarter, but he was >>>>>>>> occasionally helpful, and had a sense of humor, and was very brave at >>>>>>>> the end. >>>>>>>> >>>>>>> >>>>>>> When he wasn't busy accusing peoples' wives of immoral behaviour, >>>>>>> threatening folks with lawsuits or bodily harm, or siccing the FBI on >>>>>>> some deserving individuals. ;) >>>>>> >>>>>> Gosh, nobody's perfect. >>>>>> >>>>>>> >>>>>>> He was probably nice enough in person--we collaborated a couple of times >>>>>>> but never met in person or even talked on the phone together. >>>>>>> >>>>>>> I agree that he had guts and seems to have died very well. >>>>>> >>>>>> I used a version of his clever CD ignition (without his permission) as >>>>>> a gain-switched laser driver. Nice circuit. >>>>>> >>>>> I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >>>>> >>>>> He did an ASIC gatedriver design for us, nice design, cheap like we like it >>>>> >>>>> Suddenly we did not hear from him again, so another ASIC designer took over at that point >>>>> >>>>> He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >>>>> >>>>> Cheers >>>>> >>>>> Klaus >>>> >>>> Got to ask here, if I didn't years ago. How much different in behavior are >>>> analog circuits layed out with discrete components from the final IC >>>> itself? Let's talk pre computer simulations. For example, microwave and RF >>>> boards are constructed different from audio circuit boards, but if you >>>> look at a schematic, it's just a bunch of discretes wired together. >>> >>> It can be very simelar >>> >>> In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors >>> >>> The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. >>> >>> If you wander off, and do custom blocks, it gets a lot more expensive >>> >>> So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design >>> If not, simulations is the way forward >>> >>> And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in >>> >>> >>> Cheers >>> >>> Klaus >> >> Hmm. What about equivalent, full sized components? >> >> Take the example the 74LS00 nand gate, TI has a schematic >> >> https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html >> >> Are there equivalent transistors and diodes used in that schematic I can >> run out and buy, to make an as close to 100% electrically compatible, drop >> in replacement? >> >> I'm not even sure what the first transitor is with A and B inputs is even >> called. What is it? > > Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > > You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them.The 74LS00 is not using a multi-emitter transistor. It is not even TTL, but DTL instead. They just call it 'Schottky-TTL'. -- -TV
Reply by ●May 25, 20202020-05-25
On Monday, May 25, 2020 at 2:03:18 AM UTC-4, Tauno Voipio wrote:> On 25.5.20 07:28, Bill Sloman wrote: > > On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote: > >> Klaus Kragelund <klauskvik@hotmail.com> wrote: > >>> On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: > >>>> Klaus Kragelund <klauskvik@hotmail.com> wrote: > >>>>> On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: > >>>>>> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs > >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>> > >>>>>>> On 2020-05-21 13:38, John Larkin wrote: > >>>>>>>> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs > >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>>>> > >>>>>>>>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: > >>>>>>>>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: > >>>>>>>>>> > >>>>>>>>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: > >>>>>>>>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), > >>>>>>>>>>>> bloggs.fredbloggs.fred@gmail.com wrote: > >>>>>>>>>>>> > >>>>>>>>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: > >>>>>>>>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias > >>>>>>>>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> It's an ST1L08. > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> So why is the data sheet file en.DM00123507.pdf ? > >>>>>>>>>>>>> > >>>>>>>>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. > >>>>>>>>>>>> > >>>>>>>>>>>> Lying? It's all over the data sheet. It's how they get the millivolts > >>>>>>>>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp > >>>>>>>>>>>> from some higher voltage and over-drive an nfet follower down to > >>>>>>>>>>>> milliohms of Rds-on. > >>>>>>>>>>>> > >>>>>>>>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. > >>>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA > >>>>>>>>>>>> would be 0.24 watts dissipated. Actually, I don't need that much > >>>>>>>>>>>> current to run a couple DRAM chips. > >>>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 > >>>>>>>>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV > >>>>>>>>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V > >>>>>>>>>>> with 3% tolerance. As usual with products originating in the > >>>>>>>>>>> East, the datasheet is rather sparse about details, but I've used > >>>>>>>>>>> them and they do what I want. > >>>>>>>>>> > >>>>>>>>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. > >>>>>>>>>> > >>>>>>>>>> We need so many goofy voltages that we usually buy adjustable > >>>>>>>>>> regulators for stock. The board that I'm doing now has a 24-channel > >>>>>>>>>> analog mux to BIST the power supplies, using the dreadful Xilinx > >>>>>>>>>> 1-volt XADC that's inside their FPGAs. Free and worth it. > >>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>>> You sure are in a bad mood lately. > >>>>>>>>>>>> > >>>>>>>>>>> I've noticed that lately with some regulars here, including a few > >>>>>>>>>>> who normally exhibit decent manners. > >>>>>>>>>> > >>>>>>>>>> Well, some never show any sign of manners. They are repulsive but > >>>>>>>>>> you've got to feel sorry for them, stuck being around themselves all > >>>>>>>>>> day. > >>>>>>>>>> > >>>>>>>>>> There's a basically perfect -1 correlation between being obnoxious and > >>>>>>>>>> designing electronics. > >>>>>>>>> > >>>>>>>>> Well, now that Jim Thompson is apparently no longer with us. :( > >>>>>>>>> > >>>>>>>>> He was a bit of a statistical outlier. > >>>>>>>> > >>>>>>>> He was crabby and dismissive of people not as smart as he was, and > >>>>>>>> hostile to people that might have been smarter, but he was > >>>>>>>> occasionally helpful, and had a sense of humor, and was very brave at > >>>>>>>> the end. > >>>>>>>> > >>>>>>> > >>>>>>> When he wasn't busy accusing peoples' wives of immoral behaviour, > >>>>>>> threatening folks with lawsuits or bodily harm, or siccing the FBI on > >>>>>>> some deserving individuals. ;) > >>>>>> > >>>>>> Gosh, nobody's perfect. > >>>>>> > >>>>>>> > >>>>>>> He was probably nice enough in person--we collaborated a couple of times > >>>>>>> but never met in person or even talked on the phone together. > >>>>>>> > >>>>>>> I agree that he had guts and seems to have died very well. > >>>>>> > >>>>>> I used a version of his clever CD ignition (without his permission) as > >>>>>> a gain-switched laser driver. Nice circuit. > >>>>>> > >>>>> I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more > >>>>> > >>>>> He did an ASIC gatedriver design for us, nice design, cheap like we like it > >>>>> > >>>>> Suddenly we did not hear from him again, so another ASIC designer took over at that point > >>>>> > >>>>> He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip > >>>>> > >>>>> Cheers > >>>>> > >>>>> Klaus > >>>> > >>>> Got to ask here, if I didn't years ago. How much different in behavior are > >>>> analog circuits layed out with discrete components from the final IC > >>>> itself? Let's talk pre computer simulations. For example, microwave and RF > >>>> boards are constructed different from audio circuit boards, but if you > >>>> look at a schematic, it's just a bunch of discretes wired together. > >>> > >>> It can be very simelar > >>> > >>> In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors > >>> > >>> The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. > >>> > >>> If you wander off, and do custom blocks, it gets a lot more expensive > >>> > >>> So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design > >>> If not, simulations is the way forward > >>> > >>> And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in > >>> > >>> > >>> Cheers > >>> > >>> Klaus > >> > >> Hmm. What about equivalent, full sized components? > >> > >> Take the example the 74LS00 nand gate, TI has a schematic > >> > >> https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html > >> > >> Are there equivalent transistors and diodes used in that schematic I can > >> run out and buy, to make an as close to 100% electrically compatible, drop > >> in replacement? > >> > >> I'm not even sure what the first transitor is with A and B inputs is even > >> called. What is it? > > > > Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > > > > You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. > > > The 74LS00 is not using a multi-emitter transistor. It is not even TTL, > but DTL instead. They just call it 'Schottky-TTL'.It's rather a pointless distinction. DTL has diodes and a single transistor, so it was exceedingly slow. The LS design uses four transistors to speed up the transitions very significantly compared to a pull up resistor. The diodes vs. a dual emitter transistor don't make much of a difference. -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●May 25, 20202020-05-25
On 25/05/2020 5:28 am, Bill Sloman wrote:> > Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > > You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. >Yes, see: <www.crystalonics.com/dualEmitter.php> Were used as low-offset switches in chopper amps circa early-mid 1960s, long since obsoleted by fet switches. piglet
Reply by ●May 25, 20202020-05-25
On 23/05/2020 17:32, Cydrome Leader wrote:> Got to ask here, if I didn't years ago. How much different in behavior are > analog circuits layed out with discrete components from the final IC > itself?In my experience, for example on 0.35um BiCMOS, circuits that you could construct with discrete parts will work much the same on a chip, but with about 50x the bandwidth that one could get out of the discrete version. There are a lot of other things that work much better than what would be usual to build on a discrete board, e.g. you can expect typically <0.1% mismatch between resistors without doing anything very special, and <1mV VBE mismatch (both of these depend on device size and you can look up what standard deviation would be expected for any given size). It is also nice to be able to have a transistor exactly as big as you need it to be and no bigger, e.g. MOSFET switches with just the right tradeoff between on-resistance and gate capacitance. And of course, if you use small transistors, resistors etc. then there is no reason not to have thousands of them in your circuit, which would be costly to assemble on a circuit board. There are a few things that are worse, e.g. ~ 25% absolute tolerance on resistor values, more milliohms per square of wiring resistance than PCB traces due to thinner metal, lousy vertical PNP transistors, the unavailbility of large value or high-Q inductors, and interactions via the substrate e.g. unwanted, (and usually unsimulated) extra transistors that appear if you put other components too close together without the right guard rings. The book by the late Hans Camenzind is quite good and free: http://www.designinganalogchips.com/
Reply by ●May 25, 20202020-05-25
I found this book very informative: https://books.google.dk/books/about/ASIC_Design_in_the_Silicon_Sandbox_A_Com.html?id=34qweADwZ5kC&redir_esc=y
Reply by ●May 25, 20202020-05-25
Bill Sloman <bill.sloman@ieee.org> wrote:> On Monday, May 25, 2020 at 9:16:08 AM UTC+10, Cydrome Leader wrote: >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> > On Saturday, May 23, 2020 at 9:32:38 AM UTC+2, Cydrome Leader wrote: >> >> Klaus Kragelund <klauskvik@hotmail.com> wrote: >> >> > On Thursday, May 21, 2020 at 10:44:39 PM UTC+2, John Larkin wrote: >> >> >> On Thu, 21 May 2020 14:07:29 -0400, Phil Hobbs >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >> >> >On 2020-05-21 13:38, John Larkin wrote: >> >> >> >> On Tue, 19 May 2020 09:55:39 -0400, Phil Hobbs >> >> >> >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >> >> >> >> >> >>> On 2020-05-19 09:50, jlarkin@highlandsniptechnology.com wrote: >> >> >> >>>> On Tue, 19 May 2020 12:50:44 +0530, Pimpom <nobody@nowhere.com> wrote: >> >> >> >>>> >> >> >> >>>>> On 5/19/2020 9:31 AM, jlarkin@highlandsniptechnology.com wrote: >> >> >> >>>>>> On Mon, 18 May 2020 17:57:06 -0700 (PDT), >> >> >> >>>>>> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >> >>>>>> >> >> >> >>>>>>> On Monday, May 18, 2020 at 7:41:34 PM UTC-4, John Larkin wrote: >> >> >> >>>>>>>> ST makes a nice little LDO, super-low dropout with an aux Vbias >> >> >> >>>>>>>> supply. Saves me from rolling my own with an opamp and a mosfet. >> >> >> >>>>>>>> >> >> >> >>>>>>>> It's an ST1L08. >> >> >> >>>>>>>> >> >> >> >>>>>>>> So why is the data sheet file en.DM00123507.pdf ? >> >> >> >>>>>>> >> >> >> >>>>>>> Who cares, it's a crappy regulator. And the lying bastards with their fake dropout specs while conveniently omitting the fact that Vbias must be greater than Vout + 1.5V. >> >> >> >>>>>> >> >> >> >>>>>> Lying? It's all over the data sheet. It's how they get the millivolts >> >> >> >>>>>> of dropout. I do that when I make my own super-LDOs, power an opamp >> >> >> >>>>>> from some higher voltage and over-drive an nfet follower down to >> >> >> >>>>>> milliohms of Rds-on. >> >> >> >>>>>> >> >> >> >>>>>>> The GND current at no load of 35uA, sucks , as does that showy 80dB PSRR at 100 Hz. Battery operation usually doesn't care a whole lot about PSRR. And the thermal impedance specs are so bad, you just try getting 800mA out of it with any kind voltage headroom without using a liquid nitrogen drip. >> >> >> >>>>>>> >> >> >> >>>>>> >> >> >> >>>>>> I'm dropping a switched 1.8 to 1.5. That's 0.3 volts. Times 800 mA >> >> >> >>>>>> would be 0.24 watts dissipated. Actually, I don't need that much >> >> >> >>>>>> current to run a couple DRAM chips. >> >> >> >>>>>> >> >> >> >>>>> >> >> >> >>>>> Not directly comparable to the ST1L08 but the Holtek HT75xx-1 >> >> >> >>>>> series is nice. Max Vin 30V, 100mA, 2.5uA ground current, 25mV >> >> >> >>>>> drop-out. 16 different fixed output voltages from 2.1V to 12V >> >> >> >>>>> with 3% tolerance. As usual with products originating in the >> >> >> >>>>> East, the datasheet is rather sparse about details, but I've used >> >> >> >>>>> them and they do what I want. >> >> >> >>>> >> >> >> >>>> Is it stable with low ESR caps? We use polymers or ceramics mostly. >> >> >> >>>> >> >> >> >>>> We need so many goofy voltages that we usually buy adjustable >> >> >> >>>> regulators for stock. The board that I'm doing now has a 24-channel >> >> >> >>>> analog mux to BIST the power supplies, using the dreadful Xilinx >> >> >> >>>> 1-volt XADC that's inside their FPGAs. Free and worth it. >> >> >> >>>> >> >> >> >>>>> >> >> >> >>>>>> You sure are in a bad mood lately. >> >> >> >>>>>> >> >> >> >>>>> I've noticed that lately with some regulars here, including a few >> >> >> >>>>> who normally exhibit decent manners. >> >> >> >>>> >> >> >> >>>> Well, some never show any sign of manners. They are repulsive but >> >> >> >>>> you've got to feel sorry for them, stuck being around themselves all >> >> >> >>>> day. >> >> >> >>>> >> >> >> >>>> There's a basically perfect -1 correlation between being obnoxious and >> >> >> >>>> designing electronics. >> >> >> >>> >> >> >> >>> Well, now that Jim Thompson is apparently no longer with us. :( >> >> >> >>> >> >> >> >>> He was a bit of a statistical outlier. >> >> >> >> >> >> >> >> He was crabby and dismissive of people not as smart as he was, and >> >> >> >> hostile to people that might have been smarter, but he was >> >> >> >> occasionally helpful, and had a sense of humor, and was very brave at >> >> >> >> the end. >> >> >> >> >> >> >> > >> >> >> >When he wasn't busy accusing peoples' wives of immoral behaviour, >> >> >> >threatening folks with lawsuits or bodily harm, or siccing the FBI on >> >> >> >some deserving individuals. ;) >> >> >> >> >> >> Gosh, nobody's perfect. >> >> >> >> >> >> > >> >> >> >He was probably nice enough in person--we collaborated a couple of times >> >> >> >but never met in person or even talked on the phone together. >> >> >> > >> >> >> >I agree that he had guts and seems to have died very well. >> >> >> >> >> >> I used a version of his clever CD ignition (without his permission) as >> >> >> a gain-switched laser driver. Nice circuit. >> >> >> >> >> > I talked to him a couple of times, one review on a design when I guess he was close to not being with us any more >> >> > >> >> > He did an ASIC gatedriver design for us, nice design, cheap like we like it >> >> > >> >> > Suddenly we did not hear from him again, so another ASIC designer took over at that point >> >> > >> >> > He did minimum dev cost design, using an old version of Pspice to simulate the design, and then had another designer lay out the chip >> >> > >> >> > Cheers >> >> > >> >> > Klaus >> >> >> >> Got to ask here, if I didn't years ago. How much different in behavior are >> >> analog circuits layed out with discrete components from the final IC >> >> itself? Let's talk pre computer simulations. For example, microwave and RF >> >> boards are constructed different from audio circuit boards, but if you >> >> look at a schematic, it's just a bunch of discretes wired together. >> > >> > It can be very simelar >> > >> > In our case, to keep NRE low, we needed to use almost only predefined blocks. When you team up with a fab, they supply all datasheets and simulation models for standard blocks. So, opamps, comparators, digital blocks, voltage references, PWM circuits and individual transistors >> > >> > The blocks are proven in the technology and simulation vs real life is 100% spot on. The tools are very expensive, but they model the chip to every detail. Thus, experienced ASIC designers never need to do new revisions. >> > >> > If you wander off, and do custom blocks, it gets a lot more expensive >> > >> > So you if you find a discrete opamp that matches your ASIC block, so can do proof of concept in discrete design >> > If not, simulations is the way forward >> > >> > And by the way, prototypes with MOSIS is very cheap, you just need to wait a loooooong time from design to the first chips comes in >> > >> > >> > Cheers >> > >> > Klaus >> >> Hmm. What about equivalent, full sized components? >> >> Take the example the 74LS00 nand gate, TI has a schematic >> >> https://html.alldatasheet.com/html-pdf/27361/TI/74LS00N/73/3/74LS00N.html >> >> Are there equivalent transistors and diodes used in that schematic I can >> run out and buy, to make an as close to 100% electrically compatible, drop >> in replacement? >> >> I'm not even sure what the first transitor is with A and B inputs is even >> called. What is it? > > Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. > > You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them.A very odd device. Are there other weird semiconductors like that?
Reply by ●May 25, 20202020-05-25
piglet <erichpwagner@hotmail.com> wrote:> On 25/05/2020 5:28 am, Bill Sloman wrote: >> >> Dual-emitter transistor. You've got two contacts on the emitter region of one transistor on top of a shared base layer feeding into a share collector. >> >> You used to be able to buy it as a four lead device, a long time ago. In 1987 I had to redesign the electronics in the weighing head of the Cambridge Instruments/Metals Research GaAs single-crystal pulling machine because we couldn't buy any more of them. >> > > Yes, see: > > <www.crystalonics.com/dualEmitter.php> > > Were used as low-offset switches in chopper amps circa early-mid 1960s, > long since obsoleted by fet switches. > > pigletHa. The part numbers are a riot- like 3N62. It's nice when part numbers follow standards that convey useful information.
