On Mon, 14 Oct 2013 22:13:11 -0400, krw@attt.bizz wrote:>On Mon, 14 Oct 2013 17:27:04 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >>On Mon, 14 Oct 2013 19:15:15 -0400, krw@attt.bizz wrote: >> >>>On Mon, 14 Oct 2013 13:06:00 -0700, John Larkin >>><jlarkin@highlandtechnology.com> 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: >>>>>> >>>>>> 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. >>>> >>>>Of course, but I measured it first, powered down. Why not? >>>> >>>>It wouldn't work like an opamp closed-loop, and I need that to measure >>>>the powered-up capacitance. >>>> >>>>> >>>>>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? >>>> >>>> >>>>I've written a lot of code, but I prefer hardware design. >>>> >>>>All the things that I posted are true. >>>> >>>>Quit whining and show us some gear that you've designed... full of >>>>Maxim chips no doubt. >>> >>>What do you expect. He worked for Maxim. ...probably maxim.com. >> >>So you don't know what you measure under power-down conditions either? > >Clueless.Ignore him. He hasn't made sense in years. -- 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
Never Buy Maxim (again)
Started by ●October 13, 2013
Reply by ●October 15, 20132013-10-15
Reply by ●October 15, 20132013-10-15
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: >>> >>> 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. > > Of course, but I measured it first, powered down. Why not? > > It wouldn't work like an opamp closed-loop, and I need that to measure > the powered-up capacitance. > >> >> 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? > > > I've written a lot of code, but I prefer hardware design. > > All the things that I posted are true. > > Quit whining and show us some gear that you've designed... full of > Maxim chips no doubt. > >The input capacitance of an op amp, or really any input pin, is a combination of stray capacitance to a field and junction capacitance. [The stray capacitance to a field is a combination of capacitance in the package, bonding wire, and interconnect over substrate.] It makes no sense to measure the capacitance unless the junctions are properly biased. Seriously, this is component eval 101. Not only do you insure the device is powered up properly, but you need to insure the the SMU will not force the input out of normal operation. And of course there is the issue of nulling the test fixture capacitance. Low level measurement is a skill. It is pretty rare a chip is at fault. When the dust settles, it is nearly always pilot error. That is why eval boards are sold. Think about it. The unit is in production. Even a loser product will sell a few hundred thousand units a year, so why does it work for everyone else but not you? Pilot error. You might want to consider how sample stock at a semi is maintained. When the part is deemed sellable, tested units from that lot are put into the sample stock. Over the years, the sample stock can be pretty old. Now if there is an electrical specification change in the datasheet, the sample stock will be pulled and retested. But otherwise, the sample stock is from the very first batch. Now it will meet the electrical specification, but it could possibly be different in some manner not tested. Processes shift, wafer vendors change, etc. It is an analog world. This variance shouldn't be a big deal, but if you depend on some parameter that is not tested, don't expect the current production to match the sample stock. A lot of those op amp designs were from Gain Technology. Arizona. Need I say more? Actually they had a few good engineers, but over all mostly wankers.
Reply by ●October 15, 20132013-10-15
On 10/14/2013 2:20 PM, tm wrote:> > "miso" <miso@sushi.com> wrote in message > news:l3hi8e$ql7$1@speranza.aioe.org... >> On 10/13/2013 12:34 PM, John Larkin wrote: >>> >>> These opamps, like most Maxim parts, have nonstandard pinout. I built >>> a test >>> fixture to measure Cin. With power off, I measured 1.4 pF on the >>> non-inverting >>> input pin. >> Who measures capacitance of a part that is powered down? Doh! There >> are diodes that need to be reverse biased ya know. >> >> Do you have someone who works for you that is, well you know, a >> competent electrical engineer? Perhaps you are not suited for >> electrical engineering. Have you considered software? >> >> >> > > It's called "characterizing the part". It is way beyond a libtard such > as yourself to understand. > >No, fucking around with the part is not characterization. You do need to know how to test a part.
Reply by ●October 15, 20132013-10-15
On 10/14/2013 2:51 PM, John Larkin wrote:> On Mon, 14 Oct 2013 17:20:03 -0400, "tm" <No_one_home@white-house.gov> > wrote: > >> >> "miso" <miso@sushi.com> wrote in message >> news:l3hi8e$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? 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. ESD testing is a totally different ballgame. The vast majority of chips are designed to pass ESD as found in assembly, and not to withstand ESD from the outside world. Read the data sheet carefully. Note the ESD test is not done on a powered circuit. Remember, it is only for handling purposes. The tester can float or short the pins not under test. Generally it is more rigorous to test ESD with the power supply pins floating and the remaining pins grounded. That forces two ESD structures to turn on. ESD is tested two way. One is a characterization test. The ESD tester is hooked up and a curve tracer is attached to the pin. You examine the VI characteristics of the pin after each zap. You increase the voltage until it obviously fails. After noting at what voltage it breaks, you test a fresh unit on another pin. The other test method simply takes the QA ESD limit and zaps every pin at that limit, both positive and negative. Then the part has to pass the test program. The QA limit is pretty low, maybe 2500 to 3000v. The pins are generally above 10kV. Somebody really ought to write up a handbook of chip QA. ESD and latch-up testing confuses a lot of customers.
Reply by ●October 15, 20132013-10-15
>> >> 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? > > What "C-V behavior" are you referring to? > > ...Jim Thompson >CV is really a bad choice of words, but I don't think John means CV testings as in determining mosfet threshold. Tossing out buzzwords is generally not a good idea if you don't know what they mean.
Reply by ●October 15, 20132013-10-15
On Mon, 14 Oct 2013 21:56:43 -0700, miso <miso@sushi.com> wrote:> >>> >>> 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? >> >> What "C-V behavior" are you referring to? >> >> ...Jim Thompson >> > >CV is really a bad choice of words, but I don't think John means CV >testings as in determining mosfet threshold. > >Tossing out buzzwords is generally not a good idea if you don't know >what they mean.He's just throwing buzz words. He knows not of what he barfs. Are we surprised? No. ...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 15, 20132013-10-15
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: >>>> >>>> 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. >> >> Of course, but I measured it first, powered down. Why not? >> >> It wouldn't work like an opamp closed-loop, and I need that to measure >> the powered-up capacitance. >> >>> >>> 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? >> >> >> I've written a lot of code, but I prefer hardware design. >> >> All the things that I posted are true. >> >> Quit whining and show us some gear that you've designed... full of >> Maxim chips no doubt. >> >> >The input capacitance of an op amp, or really any input pin, is a >combination of stray capacitance to a field and junction capacitance. >[The stray capacitance to a field is a combination of capacitance in the >package, bonding wire, and interconnect over substrate.] It makes no >sense to measure the capacitance unless the junctions are properly >biased. Seriously, this is component eval 101.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?> >Not only do you insure the device is powered up properly, but you need >to insure the the SMU will not force the input out of normal operation.Boonton c-meter, 20 millivolts at 100 KHz. But I was going to measure capacitance a few different other ways, using the opamp itself. The bottom line here is noise peaking, so I was going to do that, too.>And of course there is the issue of nulling the test fixture >capacitance. Low level measurement is a skill.The fixture, without the opamp, was 0.62 pF. Customer support is, apparently, something that also requires skill.> >It is pretty rare a chip is at fault. When the dust settles, it is >nearly always pilot error. That is why eval boards are sold. Think about >it. The unit is in production. Even a loser product will sell a few >hundred thousand units a year, so why does it work for everyone else but >not you? Pilot error. > >You might want to consider how sample stock at a semi is maintained. >When the part is deemed sellable, tested units from that lot are put >into the sample stock. Over the years, the sample stock can be pretty >old. Now if there is an electrical specification change in the >datasheet, the sample stock will be pulled and retested. But otherwise, >the sample stock is from the very first batch. Now it will meet the >electrical specification, but it could possibly be different in some >manner not tested. Processes shift, wafer vendors change, etc. It is an >analog world. This variance shouldn't be a big deal, but if you depend >on some parameter that is not tested, don't expect the current >production to match the sample stock. > >A lot of those op amp designs were from Gain Technology. Arizona. Need I >say more? Actually they had a few good engineers, but over all mostly >wankers.Arizona? That explains a lot. -- 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 15, 20132013-10-15
On Mon, 14 Oct 2013 21:56:43 -0700, miso <miso@sushi.com> wrote:> >>> >>> 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? >> >> What "C-V behavior" are you referring to? >> >> ...Jim Thompson >> > >CV is really a bad choice of words, but I don't think John means CV >testings as in determining mosfet threshold. > >Tossing out buzzwords is generally not a good idea if you don't know >what they mean.OK, I'll fill you in: C means "Capacitance" V means "Voltage" -- 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 15, 20132013-10-15
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?> >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. -- 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 15, 20132013-10-15
On 10/15/2013 12:35 AM, miso 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: >>>> >>>> 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. >> >> Of course, but I measured it first, powered down. Why not? >> >> It wouldn't work like an opamp closed-loop, and I need that to measure >> the powered-up capacitance. >> >>> >>> 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? >> >> >> I've written a lot of code, but I prefer hardware design. >> >> All the things that I posted are true. >> >> Quit whining and show us some gear that you've designed... full of >> Maxim chips no doubt. >> >> > The input capacitance of an op amp, or really any input pin, is a > combination of stray capacitance to a field and junction capacitance. > [The stray capacitance to a field is a combination of capacitance in the > package, bonding wire, and interconnect over substrate.] It makes no > sense to measure the capacitance unless the junctions are properly > biased. Seriously, this is component eval 101. > > Not only do you insure the device is powered up properly, but you need > to insure the the SMU will not force the input out of normal operation. > And of course there is the issue of nulling the test fixture > capacitance. Low level measurement is a skill. > > It is pretty rare a chip is at fault. When the dust settles, it is > nearly always pilot error. That is why eval boards are sold. Think about > it. The unit is in production. Even a loser product will sell a few > hundred thousand units a year, so why does it work for everyone else but > not you? Pilot error. > > You might want to consider how sample stock at a semi is maintained. > When the part is deemed sellable, tested units from that lot are put > into the sample stock. Over the years, the sample stock can be pretty > old. Now if there is an electrical specification change in the > datasheet, the sample stock will be pulled and retested. But otherwise, > the sample stock is from the very first batch. Now it will meet the > electrical specification, but it could possibly be different in some > manner not tested. Processes shift, wafer vendors change, etc. It is an > analog world. This variance shouldn't be a big deal, but if you depend > on some parameter that is not tested, don't expect the current > production to match the sample stock. > > A lot of those op amp designs were from Gain Technology. Arizona. Need I > say more? Actually they had a few good engineers, but over all mostly > wankers.Some of us care about input capacitance a lot. For TIAs (photodiode or otherwise) the op amp's high frequency noise current is dominated by its input noise voltage differentiated by the total capacitance on the summing junction. 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 -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
