On 10/15/2013 7:04 AM, John Larkin wrote:> On Mon, 14 Oct 2013 21:35:24 -0700, miso <miso@sushi.com> wrote: > >> On 10/14/2013 1:06 PM, John Larkin wrote: >>> On Mon, 14 Oct 2013 12:54:52 -0700, miso <miso@sushi.com> wrote: >>> >>>> On 10/13/2013 12:34 PM, John Larkin wrote:> So, if the fixture is all set up and the c-meter is connected, before power > supplies are turned on, you are going to avoid looking at the c-meter? Maybe put > a black towel over the meter so you can't see it? >I wouldn't connect the capacitance meter until the circuit was powered up. I'd be using a 1MHz SMU for such a small capacitance.
Never Buy Maxim (again)
Started by ●October 13, 2013
Reply by ●October 16, 20132013-10-16
Reply by ●October 16, 20132013-10-16
On 10/15/2013 8:49 AM, Phil Hobbs wrote:> On 10/15/2013 11:46 AM, RobertMacy wrote: >> On Tue, 15 Oct 2013 08:34:21 -0700, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>>> ...snip... >>> The best op amps I know about have Cin of about 1.4 pF, so something >>> down at 0.4 pF with reasonable voltage noise would be pretty >>> interesting for some things. For instance, I recently did a front end >>> for a surface voltage tool, which basically holds a probe tip a couple >>> of mils above a spinning wafer. The work function depends very >>> strongly on surface contamination, so you can map out sub-monolayer >>> oil slicks and such like. >>> >>> Dropping the input capacitance by a whole pF would have been nice. >>> >>> Cheers >>> >>> Phil Hobbs >>> >>> >> >> >> Sadly, I've found Maxim 'specs' to be more like "intereting goals" which >> some parts actually met. > > Too good to be true? I take it that that was what John wanted to find > out. Of course engineering is divided into two sets of axes, real space > and chart space. You can do a lot of amazing things as long as you > never leave chart space. ;) > > Cheers > > Phil Hobbs >The competition would eat you alive if your part didn't meet spec. Again, people who are clueless shouldn't be making low level measurements. It really is an art. [Comment is for the other poster, not Phil.] Now input capacitance is not likely to be measured at ATE. Those specs are generally GBD (guaranteed by design). If the wafers pass their initial inspection (where the test pattern is tested) and the part passes tests with mins and maxes, you ship it. The test pattern has devices that are large enough to measure reliably, then you assume everything scales. Most patterns will be able to measure capacitance based on area and fringe. [The fringe test device has lots of fingers to increase the amount of fringe capacitance. The capacitance due to area is subtracted.] Incoming wafer inspection, at least for analog processes, is an impressive collection of test measurement equipment. Note that if the wafer fails incoming inspection, that doesn't mean it won't be used in assembly. A product engineer (or design in some cases) can sign off that the out of spec parameters will not effect the quality of the part. For instance, if the epifet is out of spec and you don't use epifets in the design, you are not going to scrap that wafer. Off the top of my head, if I saw a part with very low input capacitance, I would be trying to determine if they added a bit of input resistance to aid in the ESD structure performance. Not likely, but it would be something to look out for.
Reply by ●October 16, 20132013-10-16
On 10/15/2013 7:09 AM, John Larkin wrote:> On Mon, 14 Oct 2013 21:53:29 -0700, miso <miso@sushi.com> wrote: > >> On 10/14/2013 2:51 PM, John Larkin wrote: >>> On Mon, 14 Oct 2013 17:20:03 -0400, "tm" <No_one_home@white-house.gov> >>> wrote: >>> >>>> >>>> "miso" <miso@sushi.com> wrote in message >>>> news:l3hi8e$ql7$1@speranza.aioe.org... >>>>> On 10/13/2013 12:34 PM, John Larkin wrote: >>>>>> >>>>>> These opamps, like most Maxim parts, have nonstandard pinout. I built a >>>>>> test >>>>>> fixture to measure Cin. With power off, I measured 1.4 pF on the >>>>>> non-inverting >>>>>> input pin. >>>>> Who measures capacitance of a part that is powered down? Doh! There are >>>>> diodes that need to be reverse biased ya know. >>>>> >>>>> Do you have someone who works for you that is, well you know, a competent >>>>> electrical engineer? Perhaps you are not suited for electrical >>>>> engineering. Have you considered software? >>>>> >>>>> >>>>> >>>> >>>> It's called "characterizing the part". It is way beyond a libtard such as >>>> yourself to understand. >>>> >>> >>> I'm curious about things like ESD capacitance. Given a test setup, why >>> would anyone *not* want to measure the power-off capacitance, and then >>> determine the C-V behavior? >>> >>> >> >> ESD capacitance? We are now making up specifications? > > Don't be tedious. ESD capacitance is the capacitance of the ESD diodes. What > else would I be measuring?Unless you have a test structure, you are not measuring the capacitance of the ESD diodes, but rather whatever is on that pin, which would include the input device. [Most chips only use one diode these days since there is a tendency for boards with mixed supply voltages. Diodes to the positive rail can be a problem if the board designer is sloppy in supply sequencing (which is usually the case).> >> >> The ESD structure is part of the pin capacitance. However, nobody >> specifies the capacitance of the part that is not in a normal operating >> state. > > So that is, apparently, something that you adamantly don't want to ever measure > or know. Cover up that C-meter so you don't accidentally find out. > >I don't make useless measurements.
Reply by ●October 16, 20132013-10-16
On 10/16/2013 12:37 PM, John Larkin wrote:> On Wed, 16 Oct 2013 14:29:29 -0500, John S <Sophi.2@invalid.org> > wrote: > >> On 10/16/2013 12:40 PM, Tom Del Rosso wrote: >>> John Larkin wrote: >>>> the technical guy said that this is a single-supply opamp and might not be >>>> qualified for dual-supply >>>> operation. >>> >>> I don't have a degree and I'm hardly the most competent hobbyist, but maybe >>> I could work there. >>> >>> >> >> Perhaps you should written "I don't have a degree and I'm hardly the >> most competent hobbyist, so I'm sure I could work there." >> >> We should go apply. > > "Not getting back to potential customers" is another required skill. > >Then again, maybe Maxim apps reads SED and knows who they are dealing with.
Reply by ●October 17, 20132013-10-17
On Wed, 16 Oct 2013 19:58:40 -0700, miso <miso@sushi.com> wrote:>On 10/16/2013 12:37 PM, John Larkin wrote: >> On Wed, 16 Oct 2013 14:29:29 -0500, John S <Sophi.2@invalid.org> >> wrote: >> >>> On 10/16/2013 12:40 PM, Tom Del Rosso wrote: >>>> John Larkin wrote: >>>>> the technical guy said that this is a single-supply opamp and might not be >>>>> qualified for dual-supply >>>>> operation. >>>> >>>> I don't have a degree and I'm hardly the most competent hobbyist, but maybe >>>> I could work there. >>>> >>>> >>> >>> Perhaps you should written "I don't have a degree and I'm hardly the >>> most competent hobbyist, so I'm sure I could work there." >>> >>> We should go apply. >> >> "Not getting back to potential customers" is another required skill. >> >> > >Then again, maybe Maxim apps reads SED and knows who they are dealing with.Those who are depriving a village of its idiot ?:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●October 17, 20132013-10-17
On Wed, 16 Oct 2013 19:25:41 -0700, miso <miso@sushi.com> wrote:>On 10/15/2013 7:04 AM, John Larkin wrote: >> On Mon, 14 Oct 2013 21:35:24 -0700, miso <miso@sushi.com> wrote: >> >>> On 10/14/2013 1:06 PM, John Larkin wrote: >>>> On Mon, 14 Oct 2013 12:54:52 -0700, miso <miso@sushi.com> wrote: >>>> >>>>> On 10/13/2013 12:34 PM, John Larkin wrote: > >> So, if the fixture is all set up and the c-meter is connected, before power >> supplies are turned on, you are going to avoid looking at the c-meter? Maybe put >> a black towel over the meter so you can't see it? >> >I wouldn't connect the capacitance meter until the circuit was powered up.Or just scrunch your eyes closed really, really hard, to minimize what you learn.> >I'd be using a 1MHz SMU for such a small capacitance.The Boonton is plenty sensitive to measure 0.4 pF, or whatever the Maxim amp actually is. http://www.crscientific.com/boonton-72B.jpg But I was going to do it some other ways too: Make a non-inverting amp, G=5, and drive its + input with a fast step through a big resistor, and see what the output looks like. Build an inverting amp with big feedback resistors and look at gain/freq and noise peaking. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●October 17, 20132013-10-17
On Wed, 16 Oct 2013 19:58:40 -0700, miso <miso@sushi.com> wrote:>On 10/16/2013 12:37 PM, John Larkin wrote: >> On Wed, 16 Oct 2013 14:29:29 -0500, John S <Sophi.2@invalid.org> >> wrote: >> >>> On 10/16/2013 12:40 PM, Tom Del Rosso wrote: >>>> John Larkin wrote: >>>>> the technical guy said that this is a single-supply opamp and might not be >>>>> qualified for dual-supply >>>>> operation. >>>> >>>> I don't have a degree and I'm hardly the most competent hobbyist, but maybe >>>> I could work there. >>>> >>>> >>> >>> Perhaps you should written "I don't have a degree and I'm hardly the >>> most competent hobbyist, so I'm sure I could work there." >>> >>> We should go apply. >> >> "Not getting back to potential customers" is another required skill. >> >> > >Then again, maybe Maxim apps reads SED and knows who they are dealing with.I especially enjoyed the Maxim engineer's "not characterized for dual supply operation" comment. I now know who *I* am dealing with. Last time I used Maxim parts, we had to recall hundreds of timing modules and replace about 3000 pieces of MAX9690 comparators. They started failing after roughly a year of use, and eventually every one would have failed. The parts were actually fabbed (and maybe designed?) by a subcontractor, in Minnesota I heard. We had to make 3000 of these to replace them: https://dl.dropboxusercontent.com/u/53724080/Circuits/Break2.jpg https://dl.dropboxusercontent.com/u/53724080/Circuits/OnBoard.jpg It was rather an expensive nuisance. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●October 17, 20132013-10-17
On Wednesday, 16 October 2013 18:35:42 UTC+11, Greegor wrote:> Bill Sloman wrote > > > Jim-out-of-touch-with-reality-Thompson strikes again. > > > John Larkin exhibits a much broader spectrum of > > > ignorance than krw, and has been known to post > > > circuit diagrams and LTSpice net-lists. > > > > > > We may be arguing precedence between a flea > > > and a louse, but Larkin is definitely the > > > performing flea and krw the crawling louse. > > G > Has your wife been catching on to you, slow man? > > BS > I wonder what that was intended to mean? > > It was open ended.Which is to say more of Greegor's contentless drivel.> G > Your rundown seems like a catharsis for you. > > BS > My mother just died, and my kidney stone > BS > has been lithotripted into a very small > BS > pieces, which also seemed to turn of > BS > my right kidney for three days. > BS > > BS > Losing a parent - or what was left > BS > of her at 95 - probably qualifies > BS > as catharsis, but I don't need > BS > purification or cleansing to find > BS > an excuse to be rude about krw who > BS > must rate as the most despicable > BS > non-contributor to this usegroup. > BS > > BS > He doesn't like me much either. > > Slow Man: When avowed socialists from > other countries start manipulating > information to try to sell Socialism > to people in the USA, we don't like it.It's strictly for your own good. The shameless information manipulation that lead you to believe that socialism and communism are the same thing needs to be shown up. <snipped irrelevant stuff about someone who posts elsewhere>> I know that Jim Thompson thinks that > this usenet group is dominated by > left wing posters, but it's not as > left wing dominated as the rest of > usenet is. > > My personal belief<snipped more irrelevant prejudice> This thread started off on the defects of Maxim. A little bit of off-topic deviation is tolerable, but you are away with the fairies - of the old-fashioned asexual kind. -- Bill Sloman, Sydney
Reply by ●October 17, 20132013-10-17
On Thursday, 17 October 2013 03:28:05 UTC+11, John Fields wrote:> On Tue, 15 Oct 2013 21:18:00 -0700 (PDT), Bill Sloman > <bill.sloman@gmail.com> wrote: > >On Wednesday, 16 October 2013 14:06:58 UTC+11, Greegor wrote: > >> > >> > Jim-out-of-touch-with-reality-Thompson strikes again. > >> > John Larkin exhibits a much broader spectrum of > >> > ignorance than krw, and has been known to post > >> > circuit diagrams and LTSpice net-lists. > >> > > >> > We may be arguing precedence between a flea > >> > and a louse, but Larkin is definitely the > >> > performing flea and krw the crawling louse. > > > >> Has your wife been catching on to you, slow man? > > > >I wonder what that was intended to mean? > > > >> Your rundown seems like a catharsis for you. > > > >My mother just died, and my kidney stone has been lithotripted into a very small pieces, which also seemed to turn off my right kidney for three days. > > > >Losing a parent - or what was left of her at 95 - probably qualifies as catharsis, but I don't need purification or cleansing to find an excuse to be rude about krw who must rate as the most despicable non-contributor to this usegroup. >> If volume of non-contribution is the criterion for despicability, then > I'd conclude that he's running a distant second.It's the quality of his content which is despicable, and earns him shame of place. -- Bill Sloman, Sydney
Reply by ●October 17, 20132013-10-17
On 10/16/2013 10:21 PM, John Larkin wrote:> On Wed, 16 Oct 2013 19:58:40 -0700, miso <miso@sushi.com> wrote: > >> On 10/16/2013 12:37 PM, John Larkin wrote: >>> On Wed, 16 Oct 2013 14:29:29 -0500, John S <Sophi.2@invalid.org> >>> wrote: >>> >>>> On 10/16/2013 12:40 PM, Tom Del Rosso wrote: >>>>> John Larkin wrote: >>>>>> the technical guy said that this is a single-supply opamp and might not be >>>>>> qualified for dual-supply >>>>>> operation. >>>>> >>>>> I don't have a degree and I'm hardly the most competent hobbyist, but maybe >>>>> I could work there. >>>>> >>>>> >>>> >>>> Perhaps you should written "I don't have a degree and I'm hardly the >>>> most competent hobbyist, so I'm sure I could work there." >>>> >>>> We should go apply. >>> >>> "Not getting back to potential customers" is another required skill. >>> >>> >> >> Then again, maybe Maxim apps reads SED and knows who they are dealing with. > > I especially enjoyed the Maxim engineer's "not characterized for dual supply > operation" comment. I now know who *I* am dealing with. > > Last time I used Maxim parts, we had to recall hundreds of timing modules and > replace about 3000 pieces of MAX9690 comparators. They started failing after > roughly a year of use, and eventually every one would have failed. The parts > were actually fabbed (and maybe designed?) by a subcontractor, in Minnesota I > heard. > > We had to make 3000 of these to replace them: > > https://dl.dropboxusercontent.com/u/53724080/Circuits/Break2.jpg > > https://dl.dropboxusercontent.com/u/53724080/Circuits/OnBoard.jpg > > It was rather an expensive nuisance. > > >And what did FA say? Well assuming you contacted them. It is quite easy to find damage to chips given tools like emission microscopes. Generally failed parts are due to the customer, and you can get some good diagnostics by asking the factory how the part failed. I had Moto bitching about one of my parts. They used 4 per board. Only one position on the board would have a failed part. Moto felt a bit stupid not noticing that and simply went away, presumably finding the problem since they kept buying the parts long after the incident. Pilot error. It is nearly always pilot error. Designing ESD devices for interface chips, I spent some time in the FA lab destroying parts to understand what exactly fails. Emission microscopy detects stressed junctions, but some failures cause the juction to do ohmic. You can find those with a simple CCD, but liquid crystals is a better technique. The crystals will "boil" over the hot spot. You can pulse the chip to make the hot spot toggle, or my technique was to just leave it powered and bring a soldering iron close to the chip. The iron would get the crystals just ready to change state, making it a very sensitive technique. Minnesota parts were from VTC. To my knowledge, they didn't have any designers, just a fab.
