On Sun, 11 Apr 2021 13:15:03 -0700, jlarkin@highlandsniptechnology.com wrote:>On Sun, 11 Apr 2021 15:27:42 -0400, Joe Gwinn <joegwinn@comcast.net> >wrote: > >>On Sun, 11 Apr 2021 09:58:53 -0700, jlarkin@highlandsniptechnology.com >>wrote: >> >>>On Sun, 11 Apr 2021 02:04:37 -0400, legg <legg@nospam.magma.ca> wrote: >>> >>>>On Sat, 10 Apr 2021 09:48:49 -0700, jlarkin@highlandsniptechnology.com >>>>wrote: >>>> >>>>>Some schottky diodes have a PN junction in parallel, a "guard ring" >>>>>that acts like a parallel zener to improve ESD specs, and may help >>>>>with the fab somehow. That's OK, but at high currents the PN diode can >>>>>turn on, and it's slow to turn off and can even act like a >>>>>step-recovery diode. >>>>> >>>>>I wonder if there is a way to tell, from the data sheets, if there is >>>>>a guard ring. VI curve? CV curve? ESD specs? >>>>> >>>>>I'm pulsing a medium-small schottky pretty hard and I think I'm seeing >>>>>SRD effects. It's an ON SEMI RB520S30T1G. >>>>> >>>>>The data sheet shows a recovery time test circuit, but no recovery >>>>>time spec! The latest data sheet is rev 11; you'd think someone might >>>>>have noticed the omission by now. But at the specified 10 mA test >>>>>current, the guard ring won't conduct; so why does a schottky have a >>>>>recovery time test circuit? >>>>> >>>>>Grrrrr. >>>> >>>>I started running across Trr specs for SBDs by Matsushita/Panasonic >>>>some years ago. In fact, it was hard to determine whether some >>>>parts were schottky or not, just from their data sheets. Even harder >>>>when, in some specific cases, the title missed this info, as a typo. >>>> >>>>I assume that it simply indicates the parts' performance when inserted >>>>into a Trr test jig, with defined If, di/dt, etc. >>>> >>>>The part capacitance, and possibly physical package constraints, >>>>generate a recognizable current reversal and recovery current >>>>peak that can be related to the conventional diode recovery >>>>measurement form/profile. >>>> >>>>When pulsing parts, it's probably best to characterize performance >>>>in-circuit, rather than depend on data sheets to give all the >>>>answers, as these are characterized for conventional use. >>>> >>>>I'm unaware of guard ring parasitic conduction as ever being >>>>considered as a practical occurance in SBDs. Their effects >>>>predominate in reverse bias, after all. >>>> >>>>RL >>> >>>I once designed a 6 volt, 120 amp, 3-phase switching regulator using >>>Motorola schottky diodes. The guard rings acted like step-recovery >>>diodes, making 200 amp, 2 ns pulses. It was ugly. >> >>It's making 2 ns 200 amp pulses? So, that's how Highland Technology >>was founded? > >No, but we used to make CAMAC nuclear instrumentation modules, and >decided to make our own CAMAC crate with power supplies. They show up >on ebay now and then. Search for Highland Camac.I see two, for $50 and $60, the $50 unit being clearly bowed outward along the bottom rail, and the $60 unit for parts only.>We did get kick-started in fast stuff by a guy from Los Alamos. He >showed up one day, threw a LeCroy TDC module on my desk, and said "If >you can do this, we'll buy them."I imagine that Los Alamos had many of these TDC (Time Digital Converters), and they were Expensive. Time for some competition. When was this? How did he know to ask?> I designed an equivalent, LeCroy >heard somehow and cut their price in half on the next bid, and Harry >disqualified them.For rape and pillage. I have similar stories regarding computer platform and operating system and compiler vendors who were slow to take the term "open source" on board. But I've forgotten their names. Joe Gwinn
guard rings
Started by ●April 10, 2021
Reply by ●April 11, 20212021-04-11
Reply by ●April 11, 20212021-04-11
On Sun, 11 Apr 2021 19:29:21 +0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >> On Sat, 10 Apr 2021 20:47:41 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>>jlarkin@highlandsniptechnology.com wrote: >>>> Some schottky diodes have a PN junction in parallel, a "guard ring" >>>> that acts like a parallel zener to improve ESD specs, and may help >>>> with the fab somehow. That's OK, but at high currents the PN diode can >>>> turn on, and it's slow to turn off and can even act like a >>>> step-recovery diode. >>>> >>>> I wonder if there is a way to tell, from the data sheets, if there is >>>> a guard ring. VI curve? CV curve? ESD specs? >>>> >>>> I'm pulsing a medium-small schottky pretty hard and I think I'm seeing >>>> SRD effects. It's an ON SEMI RB520S30T1G. >>>> >>>> The data sheet shows a recovery time test circuit, but no recovery >>>> time spec! The latest data sheet is rev 11; you'd think someone might >>>> have noticed the omission by now. But at the specified 10 mA test >>>> current, the guard ring won't conduct; so why does a schottky have a >>>> recovery time test circuit? >>>> >>>> Grrrrr. >>> >>>What's the chance somebody there would even know? Like for old >>>designed stuff, do any current employees even know how or why the >>>designs exist the way they do, or undestand the test parameters being >>>used to check parts? There's a vague claim that institutional >>>knowledge is lost in 20 (or 30?) years. In the world of computers, >>>it's way faster than that. I've come across a bunch of products where >>>the manufacturer really has no idea what the specs even are, or how >>>the thing even works. >> >> I was recently looking for a fast single LVDS receiver chip, and tried >> OnSemi. Their web site is basically useless. If I search for "lvds >> receiver" I get over 4000 irrelevent hits. I emailed their tech >> support and they found one quad part. >> >> I found a good single, FIN1002, by googling. It's an old Fairchild >> part, so maybe the Fairchild people who knew about this stuff are >> gone. The TI/Burr Brown situation is similar. Nobody knows anything. > >I'm baffled by Fairchild. It seems to be that the korean packaging plant >that was setup by the real Fairchild took over the name. No idea where the >insides were fabbed or who really ran the show until On bought them. They >seemed real friendly with samples in the past, honoring requests for >rediculous quantities of stuff though. > >Can and do these places run out of masks or lose the 3 ring binder with >production steps? Like they get dropped or scuffed up? How would they make >new ones? How is the original artwork even stored for a 74LS00 or NE556?I wonder how they test the old parts. The test stands must be way obsolete. The institutional memory is gone. Go to the TI or ADI web sites. They introduce hundreds of new parts per year. How will they support all that? -- John Larkin Highland Technology, Inc The best designs are necessarily accidental.
Reply by ●April 12, 20212021-04-12
Steve Wilson wrote:> John Larkin <jlarkin@highland_atwork_technology.com> wrote: > >> On Sat, 10 Apr 2021 20:47:41 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>> jlarkin@highlandsniptechnology.com wrote: >>>> Some schottky diodes have a PN junction in parallel, a "guard ring" >>>> that acts like a parallel zener to improve ESD specs, and may help >>>> with the fab somehow. That's OK, but at high currents the PN diode can >>>> turn on, and it's slow to turn off and can even act like a >>>> step-recovery diode. >>>> >>>> I wonder if there is a way to tell, from the data sheets, if there is >>>> a guard ring. VI curve? CV curve? ESD specs? >>>> >>>> I'm pulsing a medium-small schottky pretty hard and I think I'm seeing >>>> SRD effects. It's an ON SEMI RB520S30T1G. >>>> >>>> The data sheet shows a recovery time test circuit, but no recovery >>>> time spec! The latest data sheet is rev 11; you'd think someone might >>>> have noticed the omission by now. But at the specified 10 mA test >>>> current, the guard ring won't conduct; so why does a schottky have a >>>> recovery time test circuit? >>>> >>>> Grrrrr. >>> >>> What's the chance somebody there would even know? Like for old >>> designed stuff, do any current employees even know how or why the >>> designs exist the way they do, or undestand the test parameters being >>> used to check parts? There's a vague claim that institutional >>> knowledge is lost in 20 (or 30?) years. In the world of computers, it's >>> way faster than that. I've come across a bunch of products where the >>> manufacturer really has no idea what the specs even are, or how the >>> thing even works. >> >> I was recently looking for a fast single LVDS receiver chip, and tried >> OnSemi. Their web site is basically useless. If I search for "lvds >> receiver" I get over 4000 irrelevent hits. I emailed their tech >> support and they found one quad part. >> >> I found a good single, FIN1002, by googling. It's an old Fairchild >> part, so maybe the Fairchild people who knew about this stuff are >> gone. The TI/Burr Brown situation is similar. Nobody knows anything. > > Try Octopart. They give Datasheets, Distributors, MOQ, Price. You can give > a part number or a general description: > > https://octopart.com/search?q=LVDS+receiver¤cy=USD&specs=0 > > The FIN1002 is slow. 400 MHz instead of 600 MHz: > > https://octopart.com/search?q=FIN1002¤cy=USD&specs=0By actual measurement its edges are ~170 ps. I use quite a few of them. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20212021-04-12
Cydrome Leader wrote:> John Larkin <jlarkin@highland_atwork_technology.com> wrote: >> On Sat, 10 Apr 2021 20:47:41 +0000 (UTC), Cydrome Leader >> <presence@MUNGEpanix.com> wrote: >> >>> jlarkin@highlandsniptechnology.com wrote: >>>> Some schottky diodes have a PN junction in parallel, a "guard ring" >>>> that acts like a parallel zener to improve ESD specs, and may help >>>> with the fab somehow. That's OK, but at high currents the PN diode can >>>> turn on, and it's slow to turn off and can even act like a >>>> step-recovery diode. >>>> >>>> I wonder if there is a way to tell, from the data sheets, if there is >>>> a guard ring. VI curve? CV curve? ESD specs? >>>> >>>> I'm pulsing a medium-small schottky pretty hard and I think I'm seeing >>>> SRD effects. It's an ON SEMI RB520S30T1G. >>>> >>>> The data sheet shows a recovery time test circuit, but no recovery >>>> time spec! The latest data sheet is rev 11; you'd think someone might >>>> have noticed the omission by now. But at the specified 10 mA test >>>> current, the guard ring won't conduct; so why does a schottky have a >>>> recovery time test circuit? >>>> >>>> Grrrrr. >>> >>> What's the chance somebody there would even know? Like for old >>> designed stuff, do any current employees even know how or why the >>> designs exist the way they do, or undestand the test parameters being >>> used to check parts? There's a vague claim that institutional >>> knowledge is lost in 20 (or 30?) years. In the world of computers, >>> it's way faster than that. I've come across a bunch of products where >>> the manufacturer really has no idea what the specs even are, or how >>> the thing even works. >> >> I was recently looking for a fast single LVDS receiver chip, and tried >> OnSemi. Their web site is basically useless. If I search for "lvds >> receiver" I get over 4000 irrelevent hits. I emailed their tech >> support and they found one quad part. >> >> I found a good single, FIN1002, by googling. It's an old Fairchild >> part, so maybe the Fairchild people who knew about this stuff are >> gone. The TI/Burr Brown situation is similar. Nobody knows anything. > > I'm baffled by Fairchild. It seems to be that the korean packaging plant > that was setup by the real Fairchild took over the name. No idea where the > insides were fabbed or who really ran the show until On bought them. They > seemed real friendly with samples in the past, honoring requests for > rediculous quantities of stuff though. > > Can and do these places run out of masks or lose the 3 ring binder with > production steps? Like they get dropped or scuffed up? How would they make > new ones? How is the original artwork even stored for a 74LS00 or NE556? >Fairchild has had a complicated history--they were part of National for years, then spun off, then bought by On Semi. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20212021-04-12
Am 12.04.21 um 16:11 schrieb Phil Hobbs:> > Fairchild has had a complicated history--they were part of National for > years, then spun off, then bought by On Semi.IIRC, they first belonged to Schlumberger, therefore "Schlumchild". I recently got some Fairchild LM350 via Digikey. LM350 is intended to be a stronger LM317, but the metal tab was more like a metal foil, and on one, it fell off completely, and I was gentle. I decided not to use them.> > CheersGerhard
Reply by ●April 12, 20212021-04-12
On Tuesday, April 13, 2021 at 12:11:53 AM UTC+10, Phil Hobbs wrote:> Cydrome Leader wrote: > > John Larkin <jlarkin@highland_atwork_technology.com> wrote: > >> On Sat, 10 Apr 2021 20:47:41 +0000 (UTC), Cydrome Leader > >> <pres...@MUNGEpanix.com> wrote: > >> > >>> jla...@highlandsniptechnology.com wrote:<snip>> Fairchild has had a complicated history--they were part of National for > years, then spun off, then bought by On Semi.It goes back a lot further than that, and is a whole lot more complicated https://en.wikipedia.org/wiki/Fairchild_Semiconductor started up in 1957. "In 1963, Fairchild hired Robert Widlar to design analog operational amplifiers using Fairchild's process. Since Fairchild's processes were optimized for digital circuits, Widlar collaborated with process engineer Dave Talbert. The collaboration resulted in two revolutionary products – µA702 and µA709." The first integrated circuit I ever bought was a uA709.. "In March 1967, Sporck was hired away by Peter J. Sprague to National Semiconductor. Sporck brought with him four other Fairchild personnel. Actually, Lamond had previously assembled a team of Fairchild managers in preparation to defect to Plessey, a British company. Lamond had recruited Sporck to be his own boss. When negotiations with Plessey broke down over stock options, Lamond and Sporck succumbed to Widlar's and Talbert's (who were already employed at National Semiconductor) suggestion that they look to National Semiconductor. Widlar and Talbert had earlier left Fairchild to join Molectro, which was later acquired by National Semiconductor." I worked for Plessey Pacific in Australia in 1970 and 1971, who were a subsidiary of the British parents, and did some local semiconductor design (which got turned into silicon in the UK). We were extremely fond of Bob Widlar's parts. Many years later , when I was working for Cambridge Instruments in the UK, we sold an an electron beam microfabricator to Fairchild (who had been taken over by Schlumberger at that point) which they used to make the masks for their 100k ECL which we used in some of the faster stuff we sold. Another Cambridge company - Lintech - had sold an electron beam tester to Fairchild a few years earlier. The guy who had done most ot the electronic design at Lintech - one Neil Richardson (who I'd met once or twice in Cambridge) - had installed the machine and trained the guys that used it, and impressed them enough that they ended up hiring him too. A few years later Schlumberger used him to lead a team that developed a better electron beam tester, which drove Lintech out of business. Mike Engelhardt - of LT Spice fame - was part of that team. Loads of history. -- Bil Sloman, Sydney
Reply by ●April 12, 20212021-04-12
jlarkin@highlandsniptechnology.com wrote:> On Sun, 11 Apr 2021 19:29:21 +0000 (UTC), Cydrome Leader > <presence@MUNGEpanix.com> wrote: > >>John Larkin <jlarkin@highland_atwork_technology.com> wrote: >>> On Sat, 10 Apr 2021 20:47:41 +0000 (UTC), Cydrome Leader >>> <presence@MUNGEpanix.com> wrote: >>> >>>>jlarkin@highlandsniptechnology.com wrote: >>>>> Some schottky diodes have a PN junction in parallel, a "guard ring" >>>>> that acts like a parallel zener to improve ESD specs, and may help >>>>> with the fab somehow. That's OK, but at high currents the PN diode can >>>>> turn on, and it's slow to turn off and can even act like a >>>>> step-recovery diode. >>>>> >>>>> I wonder if there is a way to tell, from the data sheets, if there is >>>>> a guard ring. VI curve? CV curve? ESD specs? >>>>> >>>>> I'm pulsing a medium-small schottky pretty hard and I think I'm seeing >>>>> SRD effects. It's an ON SEMI RB520S30T1G. >>>>> >>>>> The data sheet shows a recovery time test circuit, but no recovery >>>>> time spec! The latest data sheet is rev 11; you'd think someone might >>>>> have noticed the omission by now. But at the specified 10 mA test >>>>> current, the guard ring won't conduct; so why does a schottky have a >>>>> recovery time test circuit? >>>>> >>>>> Grrrrr. >>>> >>>>What's the chance somebody there would even know? Like for old >>>>designed stuff, do any current employees even know how or why the >>>>designs exist the way they do, or undestand the test parameters being >>>>used to check parts? There's a vague claim that institutional >>>>knowledge is lost in 20 (or 30?) years. In the world of computers, >>>>it's way faster than that. I've come across a bunch of products where >>>>the manufacturer really has no idea what the specs even are, or how >>>>the thing even works. >>> >>> I was recently looking for a fast single LVDS receiver chip, and tried >>> OnSemi. Their web site is basically useless. If I search for "lvds >>> receiver" I get over 4000 irrelevent hits. I emailed their tech >>> support and they found one quad part. >>> >>> I found a good single, FIN1002, by googling. It's an old Fairchild >>> part, so maybe the Fairchild people who knew about this stuff are >>> gone. The TI/Burr Brown situation is similar. Nobody knows anything. >> >>I'm baffled by Fairchild. It seems to be that the korean packaging plant >>that was setup by the real Fairchild took over the name. No idea where the >>insides were fabbed or who really ran the show until On bought them. They >>seemed real friendly with samples in the past, honoring requests for >>rediculous quantities of stuff though. >> >>Can and do these places run out of masks or lose the 3 ring binder with >>production steps? Like they get dropped or scuffed up? How would they make >>new ones? How is the original artwork even stored for a 74LS00 or NE556? > > I wonder how they test the old parts. The test stands must be way > obsolete. The institutional memory is gone.From what I gather about the places that supply the military with obsolete junk from filing cabinets full of old die is they use the same stuff as when the products were made, so somewhere there's a clean room with 1980s machinery in it and the same test equipment still making old/simple parts. No idea how they maintain that stuff, even the best of machines eventually fall apart. Even if you have the museum quality automated tester, how do you feed it data? tapes? floppies? reference parts? So does TI have some fab line that's stuck in 1987 still working as it did in the past? Not sure, but I assume so. I really do wonder what's in the analog only places, like Polar etc. Same thing with that- eventually the people running that stuff retire. I do some work maintaining machines that have had no support for decades. Most are simple enough to hack back into operation, but you still run into some really weird stuff like computers that backup to audio tape etc.> Go to the TI or ADI web sites. They introduce hundreds of new parts > per year. How will they support all that?Not sure. It does seem the original suppliers of parts will dump the last run of inventory, even unpackaged wafers and masks to third parties. As to whether or not I could get some old buggy USB 1.0 controller chips made for me, for any price with certification that they meet original production specs in questionable though.
