Searching some BZX884 2V4 & 3V6 zeners for test
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From: Jim Thompson on 26 Jan 2010 21:01 On Wed, 27 Jan 2010 02:57:07 +0100, Fred Bartoli <" "> wrote: >Jim Thompson a �crit : >> On Wed, 27 Jan 2010 02:15:17 +0100, Fred Bartoli <" "> wrote: >> >>> Jim Thompson a �crit : >>>> On Tue, 26 Jan 2010 16:14:45 -0800, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> Fred Bartoli wrote: >>>>>> John Larkin a �crit : >>>>>>> On Mon, 25 Jan 2010 23:37:18 +0100, Fred Bartoli <" "> wrote: >>>>>>> >>>>>>>> I'm searching some BZX884 2V4 & 3V6 NXP/Philips zeners for prototyping. >>>>>>>> These only sell by the 20k pieces wheel and I want to make some >>>>>>>> measurements before buying a wheel for maybe nothing. >>>>>>>> >>>>>>>> Anyone having a few of those to send? >>>>>>>> >>>>>>>> Thanks in advance. >>>>>>> 2.4 volt zeners are pretty terrible regulators... look at their >>>>>>> dynamic impedance and TCs. But they are cheap. >>>>>>> >>>>>> I know that, and that's why I need some to measure and make a test. I'm >>>>>> not terribly exigent for the reg and the circuit will withstand that, >>>>>> but depending on it's real curves it might pose a startup problem I want >>>>>> to check. Fairchild has some interesting curves in >>>>>> http://www.fairchildsemi.com/ds/MM%2FMM5Z3V3.pdf >>>>>> but I've seen some big datasheet variations between brands on those low >>>>>> voltage diodes, much much more than with more reasonable voltages, so I >>>>>> can't take some other brand to check. I'm not even sure that just a >>>>>> different package, still from NXP, will use the same die. I'll check >>>>>> that with them. >>>>>> >>>>>> Why try to use it? Because it's the tiniest reference I've found, even >>>>>> if crappy. Only 0.6x1mm, with leads under the body. I'll have to cram 27 >>>>>> components on a 7mm diameter pcb, plus 4 connect pads. (4 layers, >>>>>> microvia in pad) >>>>>> Some others are available in a frighteningly huge SOD523/SC79 0.9x1.7mm >>>>>> but I'm afraid I can't afford the 2.5 area. >>>>>> >>>>> If you can let off a little more about your circuit maybe there are >>>>> other options. For example the LT6700 comes in a 2mm by 3mm pack, >>>>> contact pads underneath, and in it you get two comparators plus a nice >>>>> 400mV reference: >>>>> >>>>> http://cds.linear.com/docs/Datasheet/6700123ff.pdf >>>>> >>>>> But if you consider it write me an email. It has an IMHO nasty bug >>>>> during startup that might trip you up (it almost did in my case). >>>>> >>>>> >>>>>>> Can't you get samples from a rep? >>>>>>> >>>>>> I've checked the usual suspects and none have stock, so back to square one. >>>>>> >>>>>> Oh, and reps, here in France, are really unhelpful. Yeah, I'm a just a >>>>>> (no, not a gigolo) consultant (a pretty rare species here), and the >>>>>> customer will be delighted to use half a wheel a year, so nothing to >>>>>> dream about for the reps. >>>>>> >>>>> From past experience I can only tell you that measuring a few samples >>>>> guarantees nothing with low voltage zeners. The shipped reel might be >>>>> different. You really need to get the quality control limit sheets from >>>>> the manufacturer. Done it several times, they usually give that to you >>>>> but sometimes you have to sign an NDA. Otherwise you may end up with a >>>>> product that runs fine, suddenly your client sells more than >>>>> anticipated, another reel is purchased and ... boink ... game over. And >>>>> then they all look at Monsieur le consultant :-) >>>>> >>>>> It is also not guaranteed that all the zeners on one reel are from the >>>>> same wafer or even the same production week. >>>> Isn't it sort of idiotic to look at zeners below ~5V, when there's the >>>> TL431, even CMOS versions? >>>> >>>> ...Jim Thompson >>> Have one in under a 1mmx1mm area, pads included package? >>> >>> I of course have looked that path. But you've made the die too big :-) >> >> I didn't design that particular circuit. It dates to the early '70's >> when I was making switchers for GenRad. I design similar structures >> into my custom chips... almost monthly ;-) >> >> Have you pursued the CMOS version? It should be available in a small >> package. >> > >IIRC, I did look at some CMOS version, because I could have used it as >an opamp with offseted input, which is almost what I'm doing, but I >think I came with nothing. >He he... Have a reference? Look at TLV431 and TLC431. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 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.
From: Joerg on 26 Jan 2010 21:21
Jim Thompson wrote: > On Wed, 27 Jan 2010 02:57:07 +0100, Fred Bartoli <" "> wrote: > >> Jim Thompson a �crit : >>> On Wed, 27 Jan 2010 02:15:17 +0100, Fred Bartoli <" "> wrote: >>> >>>> Jim Thompson a �crit : >>>>> On Tue, 26 Jan 2010 16:14:45 -0800, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> Fred Bartoli wrote: >>>>>>> John Larkin a �crit : >>>>>>>> On Mon, 25 Jan 2010 23:37:18 +0100, Fred Bartoli <" "> wrote: >>>>>>>> >>>>>>>>> I'm searching some BZX884 2V4 & 3V6 NXP/Philips zeners for prototyping. >>>>>>>>> These only sell by the 20k pieces wheel and I want to make some >>>>>>>>> measurements before buying a wheel for maybe nothing. >>>>>>>>> >>>>>>>>> Anyone having a few of those to send? >>>>>>>>> >>>>>>>>> Thanks in advance. >>>>>>>> 2.4 volt zeners are pretty terrible regulators... look at their >>>>>>>> dynamic impedance and TCs. But they are cheap. >>>>>>>> >>>>>>> I know that, and that's why I need some to measure and make a test. I'm >>>>>>> not terribly exigent for the reg and the circuit will withstand that, >>>>>>> but depending on it's real curves it might pose a startup problem I want >>>>>>> to check. Fairchild has some interesting curves in >>>>>>> http://www.fairchildsemi.com/ds/MM%2FMM5Z3V3.pdf >>>>>>> but I've seen some big datasheet variations between brands on those low >>>>>>> voltage diodes, much much more than with more reasonable voltages, so I >>>>>>> can't take some other brand to check. I'm not even sure that just a >>>>>>> different package, still from NXP, will use the same die. I'll check >>>>>>> that with them. >>>>>>> >>>>>>> Why try to use it? Because it's the tiniest reference I've found, even >>>>>>> if crappy. Only 0.6x1mm, with leads under the body. I'll have to cram 27 >>>>>>> components on a 7mm diameter pcb, plus 4 connect pads. (4 layers, >>>>>>> microvia in pad) >>>>>>> Some others are available in a frighteningly huge SOD523/SC79 0.9x1.7mm >>>>>>> but I'm afraid I can't afford the 2.5 area. >>>>>>> >>>>>> If you can let off a little more about your circuit maybe there are >>>>>> other options. For example the LT6700 comes in a 2mm by 3mm pack, >>>>>> contact pads underneath, and in it you get two comparators plus a nice >>>>>> 400mV reference: >>>>>> >>>>>> http://cds.linear.com/docs/Datasheet/6700123ff.pdf >>>>>> >>>>>> But if you consider it write me an email. It has an IMHO nasty bug >>>>>> during startup that might trip you up (it almost did in my case). >>>>>> >>>>>> >>>>>>>> Can't you get samples from a rep? >>>>>>>> >>>>>>> I've checked the usual suspects and none have stock, so back to square one. >>>>>>> >>>>>>> Oh, and reps, here in France, are really unhelpful. Yeah, I'm a just a >>>>>>> (no, not a gigolo) consultant (a pretty rare species here), and the >>>>>>> customer will be delighted to use half a wheel a year, so nothing to >>>>>>> dream about for the reps. >>>>>>> >>>>>> From past experience I can only tell you that measuring a few samples >>>>>> guarantees nothing with low voltage zeners. The shipped reel might be >>>>>> different. You really need to get the quality control limit sheets from >>>>>> the manufacturer. Done it several times, they usually give that to you >>>>>> but sometimes you have to sign an NDA. Otherwise you may end up with a >>>>>> product that runs fine, suddenly your client sells more than >>>>>> anticipated, another reel is purchased and ... boink ... game over. And >>>>>> then they all look at Monsieur le consultant :-) >>>>>> >>>>>> It is also not guaranteed that all the zeners on one reel are from the >>>>>> same wafer or even the same production week. >>>>> Isn't it sort of idiotic to look at zeners below ~5V, when there's the >>>>> TL431, even CMOS versions? >>>>> >>>>> ...Jim Thompson >>>> Have one in under a 1mmx1mm area, pads included package? >>>> >>>> I of course have looked that path. But you've made the die too big :-) >>> I didn't design that particular circuit. It dates to the early '70's >>> when I was making switchers for GenRad. I design similar structures >>> into my custom chips... almost monthly ;-) >>> >>> Have you pursued the CMOS version? It should be available in a small >>> package. >>> >> IIRC, I did look at some CMOS version, because I could have used it as >> an opamp with offseted input, which is almost what I'm doing, but I >> think I came with nothing. >> He he... Have a reference? > > Look at TLV431 and TLC431. > Smallest is SC70 or you have to use die and tar blob :-( -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |