Discussion of "Long term characterization of voltage references" - Page 1
Forum section: electronics / general

author: VNUTDENYER
author_rank: Contributor
timestamp: March 01, 2019, 06:49:08 pm
content: Looking for design info for ref found this "Long term characterization of voltage references". Search found no discussion. Anyone else bothered by absence of much used/discussed ref (hint LTZ.....)?

author: maginnovision
author_rank: Super Contributor
timestamp: March 01, 2019, 07:07:15 pm
content: I think that's a part of EVERY ltz thread, no?

author: VNUTDENYER
author_rank: Contributor
timestamp: March 01, 2019, 07:19:04 pm
content: Possibly, I have not read them all, yet. Actually, was wondering why the researchers left it out of test program (less stable than those tested?).

author: TiN
author_rank: Super Contributor
timestamp: March 01, 2019, 09:12:22 pm
content: What is your question precisely? What discussion you expected to see? Long-term testing is rather straightforward - keep ref happy and log it carefully over X time/years and analyze data for points that you care about, as much as you feel ready paying for that.

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: March 01, 2019, 11:11:11 pm
content: Quote from: VNUTDENYER on March 01, 2019, 07:19:04 pmWow. A conspiracy theory? I think the evidence around the internet justifies the opposite conclusion--the LTZ1000 is so stable that its almostboring, there is nothing to see, and everyone has moved on. Myself, as well, I have nine LTZ1000 references that are on 24hrs for nine months now and there is basically nothing to report. (I'm really bad about actually keeping my logged data, perhaps tomorrow I will start doing that...)Edit: I meant to say that the evidence is *negative*--if folks had seen abnormal behavior it would be widely reported since everyone uses it.Also, the LTZ1000 has the unique problem that you really need a more stable reference to measure its stability. That's non-trivial, right!?I don't have evidence but I think that if there were an ability to create a more stable reference some manufacturer would have done so. It would be lucrative.

author: VNUTDENYER
author_rank: Contributor
timestamp: March 02, 2019, 05:08:41 am
content: I think I asked it. Why not included in study of reference stability, maybe too stable to test? Sorry I brought it up.

author: 2N3055
author_rank: Super Contributor
timestamp: March 02, 2019, 01:23:49 pm
content: To clarify things:Are you are asking why the authors of the paper : "Halloin et al, ‘Long term characterization of voltage references’,submitted to IEEE trans. on Instr. & Meas." chose to test only those references in paper and not LZT1000, LM399 or LTFLU?Answer is : how would we know, if it doesn't say anywhere? Send them an E-mail, maybe they will answer.If I had to speculate, it is either that there is low power requirement (heated references need lot of power), or if you look at referenced project, it seems this thing should fly to space. Maybe these references mentioned are available in space certified version?LTZ1000 is actually very rad-hard, problem is that surrounding circuitry has to be made so too. So flying LTZ1000 to space is probably about certifying whole LTZ1000 reference module as a unit. SAme with LM399 and LTFLU..But as I said only authors know what was selection criteria in the first place.

author: razvan784
author_rank: Regular Contributor
timestamp: March 02, 2019, 02:08:35 pm
content: It's stated in the introduction: the paper discusses self-contained IC Vrefs, targeting integration on spacecraft. The LTZ1000 supporting circuitry is quite complex; I suppose they just didn't bother to make a lab setup for it, for size, complexity and maybe even cost reasons (even if the BOM cost of a LTZ-based reference is basically negligible in an aerospace application, it is not so when doing small-scale lab tests). Also, they are not interested in really long time scales (again, stated in the introduction: voltage metrology applications are outside the scope of the article) but rather medium time scales on the order of days (1E-5 Hz).Edit: I also think that the LM399 is too noisy for their target application and the LTZ1000 is too fragile and finicky. LTFLU-1 is a custom design and not commercially available.

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: March 02, 2019, 08:11:36 pm
content: Quote from: VNUTDENYER on March 02, 2019, 05:08:41 amWell no, don't feel bad for bringing it up--feel bad for not including a reference to the paper. I *thought* you were asking a general question. It was really very specific. It's like you thought the whole internet was reading over your shoulder!Anyhoo, lets move on--for that paper my personal opinion was that, since its space based they are concerned about power consumption. It is rather high with the LTZ, so maybe they eliminated it right away on that criterion. I agree, it would be nice to know.If you contact the authors and they reply please post here (assuming they allow it, of course).