Author Topic: what happened to LTZ1000 stocks?  (Read 4269 times)

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Offline zhtoor

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what happened to LTZ1000 stocks?
« on: November 15, 2017, 12:38:13 AM »
is analog devices at "work" here ?

regards.
 

Offline Andreas

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Re: what happened to LTZ1000 stocks?
« Reply #1 on: November 15, 2017, 01:10:12 AM »
Hello,

most probably Keysight will offer his brand new 34480 in 6-12 months  8)

with best regards

Andreas
 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #2 on: November 15, 2017, 01:13:22 AM »
Hello,

most probably Keysight will offer his brand new 34480 in 6-12 months  8)

with best regards

Andreas

doubt that very much.
keysight has lost its mettle.

best regards.
 

Offline NANDBlog

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Re: what happened to LTZ1000 stocks?
« Reply #3 on: November 15, 2017, 01:33:34 AM »
Hello,

most probably Keysight will offer his brand new 34480 in 6-12 months  8)

with best regards

Andreas

Those 10-100 LTZ1000s that are usually stocked at Digikey and Mouser can easily purchased by a single even small manufacturer, if they need them in a hurry.
 

Offline TiN

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Re: what happened to LTZ1000 stocks?
« Reply #4 on: November 15, 2017, 03:08:31 AM »
Hello,

most probably Keysight will offer his brand new 34480 in 6-12 months  8)

with best regards

Andreas

Those 10-100 LTZ1000s that are usually stocked at Digikey and Mouser can easily purchased by a single even small manufacturer, if they need them in a hurry.

It's not available on DK either since August.
« Last Edit: November 15, 2017, 03:29:31 AM by TiN »
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Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #5 on: November 15, 2017, 03:39:55 AM »
Linear Tech is evaluating some new materials suppliers and testing them in their process for LTZ1000a, they tell me they will be able to ramp up production very soon.    We just got notified our August order will be shipping in the next week or thereabouts.

The LTZ is not going anywhere and will remain in the parts catalog, it will eventually become branded AD but right now it is still LT.
 
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Online chuckb

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Re: what happened to LTZ1000 stocks?
« Reply #6 on: November 15, 2017, 03:45:32 AM »
I'm seeing a 4-6 week leadtime through Digikey. Order the parts and they will be shipped when Digikey gets them. My credit card does not get charged until the parts ship. Don't wait till you need them to order them.
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #7 on: November 15, 2017, 03:50:42 AM »
Linear Tech is evaluating some new materials suppliers and testing them in their process for LTZ1000a, they tell me they will be able to ramp up production very soon.    We just got notified our August order will be shipping in the next week or thereabouts.

The LTZ is not going anywhere and will remain in the parts catalog, it will eventually become branded AD but right now it is still LT.

"new materials suppliers" and "ramp-up" leads me to ask:-

1. why new materials on an already proven die?
2. why was the production stopped / slowed-down?

dangerously close to the time of AD takeover, what gives?  :-//

regards.
 

Offline Kleinstein

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Re: what happened to LTZ1000 stocks?
« Reply #8 on: November 15, 2017, 04:08:43 AM »
They might need relative special wafers to get the best performance. A new source might give lower cost or better performance or just an alternative in case the old source an not deliver. Also the TO99 case is kind of special now - not used that often anymore.

Not sure this delay is related to the AD merger. Though it is possible the the merger did add a little to the delay as management was busy with other things.

Such a special chip will not be produced every weak - more like a batch for the next months or year. It might also include quite some lead time for extended anneals / curing and a chance for a batch to turn out bad, thus an unexpected delay.
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #9 on: November 15, 2017, 04:13:12 AM »
Also the TO99 case is kind of special now - not used that often anymore.

LTZ1000P(CZ) 8 pin DIP/SOIC package?  :-DD
 

Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #10 on: November 15, 2017, 04:27:15 AM »
Again:  My LT apps engineer got the info from their Vref line production manager, and the design has NOT changed at all.  They had to evaluate a new materials supplier (not wafers, that's all they said), do some detailed spec-sheet performance testing to make sure all is well, and then resume shipping.  You can't test LTZ's overnight.  This apparently has nothing to do with merger; I wouldn't read too much into it.  This happens in the low ppm world.

We have seen delays like this before now and then - these are not exactly easy to make and test, and remember you've got the big customers ahead of you in line. 
 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #11 on: November 15, 2017, 04:48:43 AM »
This happens in the low ppm world.

low ppm = low profits per month.

what would be LTZ1000 contribution to the bottom line? 1-2 million per year?

regards.
 

Offline GreggD

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Re: what happened to LTZ1000 stocks?
« Reply #12 on: November 15, 2017, 04:57:48 AM »
In TO-5, Arrow has 14, Chip1stop has 17
 

Offline Andreas

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Re: what happened to LTZ1000 stocks?
« Reply #13 on: November 15, 2017, 05:40:29 AM »
Linear Tech is evaluating some new materials suppliers and testing them in their process for LTZ1000a,

Hello,

I hope that they will not change the die attach.
Otherwise I fear the stability will not be the same as before.
(Similar to the LT1027 which has suffered from the LS8 package/die attach in my opinion).

with best regards

Andreas
 

Offline floobydust

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Re: what happened to LTZ1000 stocks?
« Reply #14 on: November 15, 2017, 07:06:09 AM »
If it's not the wafer, what "new materials supplier" is there?  Who's putting the gun to their head to change suppliers on this sole-sourced part.
Logically, continue making it with the old material until the new material gets approved.
Any quality/supply issues will cause big trouble for manufacturers dependent on it.

I'm skeptical. Mergers and acquisitions are never good for products.
AD will surely consolidate fab, remove redundant teams, "improve" things to lower costs. Increasing shareholder value is paramount and great art is never about that.
 

Offline branadic

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Re: what happened to LTZ1000 stocks?
« Reply #15 on: November 15, 2017, 07:24:59 AM »
Maybe Analog Devices needs the LTZ for their own reference modules on AD5791. See the article High Precision Voltage Source from Oct. 2017.  :-DD

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Offline Edwin G. Pettis

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Re: what happened to LTZ1000 stocks?
« Reply #16 on: November 15, 2017, 07:39:47 AM »
Problems with material suppliers is nothing new, my guess is that LT's current material supplier is having problems with the purity and it is causing problems for the LTZ, this would not be a wafer level problem, given the higher performance level, impurities are critical.  We've had problems with resistance alloy suppliers in the past, going back decades, which caused a lot of trouble.  This happens and often finding a new supplier is the solution.  Rest assured, there is no change to the LTZ as it is made, there is absolutely no move to put it in a different package, it wouldn't work to spec otherwise.  I rather doubt it has anything to do with the die leads either, but exactly what is causing the problem is unknown outside of Linear Tech as such.

Back in the old days, we had vertical manufacturing, a semi house did everything, raw materials came in one door and the finished product came out another door, everything done under one roof in effect.  Nobody has that kind of integration now, it has gotten too expensive and too many regulations.  And with that change, managing quality control of materials became much more difficult, many books and articles have been written about the supply chain and how it is spread around the world complicating quality control.  It is no simple matter these days.

This kind of disruption happens all the time in ICs, if you kept an eye on delivery dates, you can always tell when supply is not meeting demand for a myriad of reasons and raw materials are often at the head of the list.  A lot of those raw materials comes from countries that are not the most stable on the planet.  Those that process the raw materials are also scattered all over the globe, just try keeping control of all of the variables involved all the time.  The fact is even highly reputable companies can run into problems and it can take a lot of time to fix it, customers can't wait very long in most instances.
 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #17 on: November 15, 2017, 07:52:29 AM »
Maybe Analog Devices needs the LTZ for their own reference modules on AD5791. See the article High Precision Voltage Source from Oct. 2017.  :-DD

EVAL-AD5791SDZ expected availability @ RS Components on 21.02.2018



-branadic-

note the "x1000" mark, would that mean - AD1000? (relabelled)  :-DD

regards.
 

Online Echo88

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Re: what happened to LTZ1000 stocks?
« Reply #18 on: November 15, 2017, 08:04:06 AM »
Do they have documentation on this X1000-board? Since the old standard AD5791-base-board has LTZ-1000-layout errors according to Mickle T.
« Last Edit: November 15, 2017, 07:59:25 PM by Echo88 »
 

Offline EEVblog

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Re: what happened to LTZ1000 stocks?
« Reply #19 on: November 15, 2017, 09:46:49 AM »
low ppm = low profits per month.
what would be LTZ1000 contribution to the bottom line? 1-2 million per year?

You could say that about almost every one of the thousands of chips in their portfolio. Small profits across thousands of different products is their business.
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #20 on: November 15, 2017, 10:01:06 AM »
low ppm = low profits per month.
what would be LTZ1000 contribution to the bottom line? 1-2 million per year?

You could say that about almost every one of the thousands of chips in their portfolio. Small profits across thousands of different products is their business.

hello,

lets look at a little bit of history:-

1. REFAMP SZA263 by motorola used in 731's - production dropped - not feasible / profitable.
2. LTFLU done by LT+Fluke used (internally) in 732's - production dropped (?) - not feasible / profitable.
3. LM399/199 done by National Carried over by LT - production? (questionable production future?)
4. LTZ1000 done by LT acquired by ADI - just compare volumes of a typical power product with a high-end vref like LTZ1000 - questionable profits.

i for one don't want to sound alarmist, but there might be financial difficulties in sustaining the high-end production line.
(i would definitely want LT/ADI to continue producing a stellar product like LTZ1000, even at a price hike - reasonable that is)

second source anyone? microsemi? linearsystems? (or shanghai factory #17  :-DD)
or maybe availability of the bare die product?

regards.
« Last Edit: November 15, 2017, 10:31:46 AM by zhtoor »
 

Offline floobydust

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Re: what happened to LTZ1000 stocks?
« Reply #21 on: November 15, 2017, 01:14:54 PM »
LTZ1000A is USD $60 (USD $70 in Canada) from Digikey. Surely there's room for decent margin and possibly another manufacturer now. I doubt Fluke or Keysight etc. like being held by their balls on this.

I'm not sure what the production time constant is - from start to finish.
Synthetic quartz crystals take 2-6 months to grow (Epson), an example of a long time-constant. By the time you realize you have a problem, it's too late. The batch is in the garbage and hmmm what caused it.

You must have a stable process, patient (management), tolerate low yields, have expensive test equipment, highly skilled people -  a precision manufacturing environment with some art to it.
That is harder and harder to accomplish and I find larger corporations fumble around, bungle it and then give up. Impatience, dumb leadership, and weak commitment all contribute.
Smaller companies are agile, flexible and LT was pretty good for niche products of higher quality.

So I think these parts are dropped due to the unique production requirements and oddball nature of them, compared to the big corp's "let's pound out the op-amps and make $" business plan.

 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #22 on: November 15, 2017, 02:40:03 PM »
I doubt Fluke or Keysight etc. like being held by their balls on this.

KFLU-1K?  :-DD

on a more serious note, how about an open-source-chip project as in crowd-sourcing, maybe rope-in TSMC or some other fab?
(Bob Dobkin could be of some help  ;))

regards.
« Last Edit: November 15, 2017, 02:44:21 PM by zhtoor »
 

Online blueskull

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Re: what happened to LTZ1000 stocks?
« Reply #23 on: November 15, 2017, 02:49:51 PM »
I think the so called new material is not for performance, but for environmental reasons. I wouldn't risk my reputation on my flagship product for some minor performance tweaking.
Either their supplier is asking for too much price to force them to evaluate a new material, or it's being banned by some government EPA rules (think of asbestos).
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #24 on: November 15, 2017, 03:00:22 PM »
or maybe a cheaper package supplier from china?
(or LT/ADI have neophytes like me in the CAD section!)

regards.
« Last Edit: November 15, 2017, 03:05:02 PM by zhtoor »
 

Offline VintageNut

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Offline NANDBlog

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Re: what happened to LTZ1000 stocks?
« Reply #26 on: November 15, 2017, 08:38:16 PM »
If it's not the wafer, what "new materials supplier" is there?  Who's putting the gun to their head to change suppliers on this sole-sourced part.
Logically, continue making it with the old material until the new material gets approved.
Any quality/supply issues will cause big trouble for manufacturers dependent on it.

I'm skeptical. Mergers and acquisitions are never good for products.
AD will surely consolidate fab, remove redundant teams, "improve" things to lower costs. Increasing shareholder value is paramount and great art is never about that.
Can be the steel in the metal can, can be the kovar for the leads, maybe it is the isolation standoff. None of which should effect the performance too much.
Dont be afraid for the LTZ1000. I'm sure that Agilent and Linear signed a contract for the availability, which is a bounding contract for Keys. and Analog.
Also, if they change something, they need time to verify it. This is not a digital gate, where you measure the rise time, and say that it is OK. Just making sure, that the drift for the first 2x1000 hours is OK: 3 months. With about 12 weeks extra as lead time.

Linear has a very different approach for the market. They make products, which sells in the 1000s and not the millions, and they have higher profit margin on it. Why sell microcontollers with billions of transistors in it, and have 5 cents of profit on each, when you can sell an opamp with a dollar of profit on it. The LT5400, which is "just" 4 resistor sells for almost the same as a Apple A8.
 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #27 on: November 16, 2017, 11:11:58 AM »
I'm sure that Agilent and Linear signed a contract for the availability, which is a bounding contract for Keys. and Analog.

should be so.
anyways, this blog can *maybe* change their mind if they plan to do any hanky-panky.

viva la voltnutland! :box:

regards.
« Last Edit: November 16, 2017, 11:15:48 AM by zhtoor »
 

Offline Muxr

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Re: what happened to LTZ1000 stocks?
« Reply #28 on: November 16, 2017, 03:46:41 PM »
I ordered a LTZ1000A 4 months ago directly from Linear's website.. still waiting.
 

Offline montemcguire

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Re: what happened to LTZ1000 stocks?
« Reply #29 on: November 16, 2017, 05:46:19 PM »
Arrow has 14 LTZ1000CH#PBF right now. It's not the 'A' version, but it is an LTZ1000
 
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Offline bopcph

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Re: what happened to LTZ1000 stocks?
« Reply #30 on: November 17, 2017, 05:25:28 AM »
I am pretty sure (99%) the LTZ1000 won't go into obsolescence in near future.

Ever heard of the mil./space version of LTZ1000 with a price tag of US$1500 -
might be DKK 1500 =US$ 300, pardon but I remember the number 1500 and not the sales channel, the number had me running in search for another source  :palm:

What I do remember is the claim of "longe lead-time EOL sourcing", "One known fab only" (US as I remember), "narrowed wafer specs", "preconditioned" ...... and a documentation the size of the holy book  ;)

Any one ever thought of what it takes to produce and prove a product that stable that other people are willing to bet 10-11 digit US$ project on it ?
If you "own" that product you won't "kill" it  8)
 

Offline gamalot

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Re: what happened to LTZ1000 stocks?
« Reply #31 on: November 17, 2017, 05:46:36 AM »
Chip1stop has 17 LTZ1000CH#PBF in stock.
 

Offline Muxr

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Re: what happened to LTZ1000 stocks?
« Reply #32 on: November 17, 2017, 06:34:12 AM »
I ordered a LTZ1000A 4 months ago directly from Linear's website.. still waiting.
Quoting myself to provide an update. I contacted Linear.. they said they'd be shipping me one today. So I guess my order just got forgotten somehow. Or they felt bad and are giving me one from a secret stash.
 

Offline DiligentMinds.com

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Re: what happened to LTZ1000 stocks?
« Reply #33 on: November 17, 2017, 06:37:37 AM »
There are a few out there:

https://octopart.com/search?q=LTZ1000&avg_avail=(1__*)&start=0

I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.  This is related to contamination of the junction layers with metals, (that are normally extracted during processing by infusion of phosphorous on the back side of the wafer, followed by a long bake at 900oC) and/or radioactive particle contamination.  I suspect that something in the fab has gone Wr0nG, and they are trying to fix it.  I wonder if this is related to the recent contamination in the atmosphere in the northern hemisphere with radioactive contaminants.  Maybe it's time to coat the chip with super-pure silicone RTV before sealing the package?   :-//

I'm going to shoot a question at LTC and see if they will cough up the information...

-Ken
« Last Edit: November 17, 2017, 06:40:27 AM by DiligentMinds.com »
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #34 on: November 17, 2017, 06:41:18 AM »
Or they felt bad and are giving me one from a secret stash.

 :-+
 

Offline hwj-d

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Re: what happened to LTZ1000 stocks?
« Reply #35 on: November 17, 2017, 09:58:59 AM »
One non A type from this 14 Arrows stock is ordered an on the way to me.  :popcorn:
The sparrow in the hand, is better than pain in the b..., or so ...   ;D
who knows what else will happen  :o
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #36 on: November 17, 2017, 11:59:36 AM »
a documentation the size of the holy book  ;)

this forum would love to have access to *that* holy book  >:D

regards.
« Last Edit: November 17, 2017, 12:02:02 PM by zhtoor »
 

Offline Kleinstein

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Re: what happened to LTZ1000 stocks?
« Reply #37 on: November 17, 2017, 09:53:02 PM »
...
I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.  This is related to contamination of the junction layers with metals, (that are normally extracted during processing by infusion of phosphorous on the back side of the wafer, followed by a long bake at 900oC) and/or radioactive particle contamination.  I suspect that something in the fab has gone Wr0nG, and they are trying to fix it.  I wonder if this is related to the recent contamination in the atmosphere in the northern hemisphere with radioactive contaminants.  Maybe it's time to coat the chip with super-pure silicone RTV before sealing the package?   :-//

I'm going to shoot a question at LTC and see if they will cough up the information...

-Ken

Radioactive contamination is not leading to popcorn noise. If at all one would get something like a few random errors in high densitiy DRAM of flash chips due to high energy alpha decay. Today most of those errors won't be visible due to chip internal error correction. So it is definitely not due to radioactive contamination.

The 1/f and popcorn noise is more due to chemical contamination's and maybe crystal defects. This might be hard to track, as it can be really trace amounts, both in the fab and in the wafers. Especially popcorn noise is something about a single defect (e.g. wrong atom) sitting at a sensitive place. More such defects at not so sensitive places give a source of 1/f noise.

Usually there is no way to get rid of trace contamination - it's all about starting clean and keep it clean. A common practice is removing some of the surface by etching to get rid of damages from cutting the wafers.

In the early days they has a story about yield being much lower after lunch. The anecdote is they got the yield back up, when they offered free lunch, as they traced the problem back to copper contamination from the money the workers used to pay the lunch.
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #38 on: November 17, 2017, 10:40:01 PM »
I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.

hello Ken,

can you expound on "a lot of noise", ie; some measurement details? how far off-spec or in-spec?

best regards.
 

Offline bopcph

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Re: what happened to LTZ1000 stocks?
« Reply #39 on: November 18, 2017, 12:22:39 AM »
a documentation the size of the holy book  ;)

this forum would love to have access to *that* holy book  >:D

regards.

I will try to retrace my browser history  ???
 

Offline mimmus78

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Re: what happened to LTZ1000 stocks?
« Reply #40 on: November 18, 2017, 01:35:54 AM »
I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.

hello Ken,

can you expound on "a lot of noise", ie; some measurement details? how far off-spec or in-spec?

best regards.
I was asking this too.

Inviato dal mio Nexus 6P utilizzando Tapatalk

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-> OR my Blog @ 118volt [IT][EN]
 

Offline DiligentMinds.com

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Re: what happened to LTZ1000 stocks?
« Reply #41 on: November 18, 2017, 06:10:57 AM »
I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.

hello Ken,

can you expound on "a lot of noise", ie; some measurement details? how far off-spec or in-spec?

best regards.
I was asking this too.

Inviato dal mio Nexus 6P utilizzando Tapatalk

The data sheet specifies 1.2uVpp (typical) and 2.0uVpp (maximum) for 1/f noise (and, presumably, popcorn noise as well)-- some (a very few actually) recent parts are showing LF noise that is over the data sheet limit of 2.0uVpp.  "Out Of Part Spec" [OOPS] == BAD PART.  I'm assuming here that a proper circuit is used and a "draft excluder" (some kind of cap) is placed over the LTZ top and bottom-- and the part is still OOPS.
« Last Edit: November 18, 2017, 09:45:18 AM by DiligentMinds.com »
 
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Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #42 on: November 18, 2017, 06:28:13 AM »
What is the source of "Some recent parts?"?  How many are we talking about and what date codes??  Are these actual real parts from LT or authorized distributor?  Was this on a known good PCB design?

Normally it is -very- rare to see a real LT factory checked LTZ out of spec on a properly built board, and we've seen about zero of what you're talking about on recent batches this year.  I think over the several hundred I can count the bad LTZ's on one or two fingers, and LT replaced them since they came directly from LT (They will also do that if they come from a real authorized distributor, but not if you bought them from some broker or eBay, etc).

It is common to see the noise on these parts from the shady parts brokers / dealers trying to peddle the "floor sweeping" rejected / fake parts that somehow got legs and walked out of the fab, or sometimes someone got hold of some reject die and repackaged them.  You can usually tell when the parts aren't sealed in the proper tray with the LT logo.

Those "used" LTZ parts on eBay are a bit suspect also - you never know what blowtorch was used to get the parts demounted.  You might get lucky and they are fine, and maybe not.

We've always ordered direct from LT and never had any real problem.

 
 

Offline Andreas

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Re: what happened to LTZ1000 stocks?
« Reply #43 on: November 18, 2017, 07:47:29 AM »
Hello,

noise testing is not cheap.
So I guess that LT is only measuring wideband noise for a short time and not the 1/f noise in excess of 10 seconds during production.
The closer you look the more noise you will find.
I have also the impression that newer buried zeners (AD586/AD587) have more (popcorn) noise but I will have to verify this with older stock devices.

My LTZ#5 DC 0945 via official distributor has also a lot of popcorn noise in excess of 2uV.
If you look at the "right" 10 seconds measurement duration you will see only the typical 1.2uVpp noise.

With best regards

Andreas
 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #44 on: November 18, 2017, 08:14:27 AM »
@Ken (?Dobkin), @MisterDiodes

does anybody know the yield percentage on the LTZ1000 die?

regards.
 

Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #45 on: November 18, 2017, 08:21:53 AM »
Andreas,
...that's why the datasheet clearly states "about 1.2uV noise".  2uV p-p is listed as max, and that data looks still in the ballpark of that.  You also have take your measurement uncertainty into account and look at how far your experiment drifts in the same time frame, as well as the overall noise floor of your setup.  Are you scanning other known Vrefs simultaneously to compare?  When you're down at uV levels that helps to distinguish noise on a -single- device from your experiment setup noise.  The earlier part of your data is quieter for sure, did something get switched on nearby?
« Last Edit: November 18, 2017, 08:41:21 AM by MisterDiodes »
 

Offline Andreas

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Re: what happened to LTZ1000 stocks?
« Reply #46 on: November 18, 2017, 09:47:07 AM »
did something get switched on nearby?

No,

its clearly popcorn noise. And whole setup including scope is battery supplied.

As I measure with a filter amplifier (HP = 0.1Hz) you see only the rising and falling edge as triangle pulse
when the duration of the jump is longer than about 1 second.

Noise floor is typical 100-120uVpp so far away from the 1.2uVpp of the LTZ. (see noise measurement thread).

with best regards

Andreas
 

Offline Kleinstein

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Re: what happened to LTZ1000 stocks?
« Reply #47 on: November 18, 2017, 10:11:48 AM »
I would expect the LTZ1000 to be tested for a little longer than 10 seconds. It already needs some time to get a stable temperature - so no way to do a super fast test anyway. Popcorn noise is likely one of the more important reasons to do the checks and sort out failing units.

However with popcorn noise is can be difficult to detect - especially that type of noise with more infrequent jumps. Chances are one would not notice this in a short interval of maybe 30 seconds. Those very low frequency popcorn cases are the really bad ones, as one never knows and longer averaging also does not help that much. With the more frequent and symmetric jumps, like in TIN's jummpy sample from Ebay one has in theory the chance to detect and even correct for this.
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #48 on: November 18, 2017, 10:22:27 AM »
I would expect the LTZ1000 to be tested for a little longer than 10 seconds. It already needs some time to get a stable temperature - so no way to do a super fast test anyway. Popcorn noise is likely one of the more important reasons to do the checks and sort out failing units.

However with popcorn noise is can be difficult to detect - especially that type of noise with more infrequent jumps. Chances are one would not notice this in a short interval of maybe 30 seconds. Those very low frequency popcorn cases are the really bad ones, as one never knows and longer averaging also does not help that much. With the more frequent and symmetric jumps, like in TIN's jummpy sample from Ebay one has in theory the chance to detect and even correct for this.

hello,

looks like the biggest bottleneck in the production of LTZ1000 would be effective noise testing.

regards.
 

Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #49 on: November 18, 2017, 01:45:39 PM »
I still fail to see the big LTZ datasheet spec "Oops" in Andreas' data.  That shows a part still within the realm of datasheet specs it looks to me:  It's showing clearly a P-P value of ~2uV (equipment / experiment noise -floor- limits are not known) which is the datasheet value.  Of course the longer you measure, the more likely you'll see more noise.  Especially as 1/f creeps in.  Double the measure time and you get another octave's worth of 1/f possibilities.  If there is -some- popcorn noise, it will probably still be able to pass the LT quality check. 

The problem we saw before on just one or two parts was an excursion more like 6 or 8uV P-P across 10 sec - clearly out of spec.  Those got replaced.

DigilentMinds: Were you thinking about a bigger "oops" deviation from datasheet value?  That's what I was curious about.  How many parts and what date codes are we talking about??






« Last Edit: November 19, 2017, 11:43:22 AM by MisterDiodes »
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #50 on: November 18, 2017, 01:57:52 PM »
I still fail to see the big LTZ datasheet spec "Oops" in Andreas' data.  That shows a part still within the realm of datasheet specs it looks to me:  It's showing clearly a P-P value of ~2uV (equipment / experiment noise -floor- limits are not known) which is the datasheet value.  Of course the longer you measure, the more likely you'll see more noise.  Especially as 1/f creeps in.  Double the measure time and you get another octave's worth of 1/f possibilities.  If there is -some- popcorn noise, it will probably still be able to pass the LT quality check. 

The problem we saw before on just one or two parts was an excursion more like 6 or 8uV P-P across 10 sec - clearly out of spec.  Those got replaced.

DigilentKen: Were you thinking about a bigger "oops" deviation from datasheet value?  That's what I was curious about.  How many parts and what date codes are we talking about??

hello,

what *is* the LTZ1000 go/nogo quality check with respect to noise specifically?

(maybe another thread about LTZ1000 noise testing is in order)

regards.
« Last Edit: November 18, 2017, 02:00:32 PM by zhtoor »
 

Offline Andreas

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Re: what happened to LTZ1000 stocks?
« Reply #51 on: November 18, 2017, 04:21:35 PM »
It already needs some time to get a stable temperature

RTFM

Note 2: All testing is done at 25°C. Pulse testing is used for LTZ1000A to
minimize temperature rise during testing.

And against other data sheets like LT1021 or LT1236 there is no 100% noise testing specified.

The newer data sheet of the newer "3rd generation buried zener" LT1027 already specifies a method with reduced testing time

Note 5: RMS noise is measured with an 8-pole bandpass filter with a
center frequency of 30Hz and a Q of 1.5. The filter output is then rectified
and integrated for a fixed time period, resulting in an average, as opposed
to RMS voltage. A correction factor is used to convert average to RMS.
This value is then used to obtain RMS noise voltage in the 10Hz to 1000Hz
frequency band. This test also screens for low frequency "popcorn" noise
within the bandwidth of the filter. Consult factory for 100% 0.1Hz to 10Hz
noise testing.

So the LT1027 is tested from around 22 -41 Hz (with minimum 50 ms testing time).
(no 100% test specified).

In the LTZ1000 datasheet there is no noise testing specified.
(it is always more essential to know what is missing in a data sheet as that what is specced).

with best regards

Andreas



 
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Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #52 on: November 18, 2017, 06:34:22 PM »
RTFM

hello andreas,

your observation is very correct:-

TNFM (There is No ****ing Manual with respect to noise testing of LTZ1000)  |O

best regards.
 

Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #53 on: November 18, 2017, 09:52:37 PM »
...Except the datasheet does clearly states a 2uV p-p max noise, does it not?  Which is what Andreas' part is doing, and I would say is operating properly - at least from the graph shown.  The datasheet doesn't distinguish the "type" of noise, but you do get a boundary limit.  That 2uV p-p limit is still <0.3ppm p-p on a 7.15V scale, and difficult to measure accurately especially as a real -absolute- value change. 

That noise level is also in the realm of contributing binding post thermals, air drafts, EMI and lots of other causes outside the LTZ can.

DigilentMinds was referring to something I think operating farther -outside the bounds- of the datasheet limits, and that's something that piqued my interest.  From what I've seen that doesn't happen often with LTZ's (on proper PCB, proper draft protection, noise shielding, etc.), and I was curious about the date codes of those parts involved, if known.
« Last Edit: November 19, 2017, 11:43:56 AM by MisterDiodes »
 

Offline bopcph

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Re: what happened to LTZ1000 stocks?
« Reply #54 on: November 21, 2017, 03:57:22 AM »
That 2uV p-p limit is still <0.3ppm p-p on a 7.15V scale,

I'm glad I don't have an 8½ digit DMM - even a LTZ1000 inside spec's ain't good enough to calibrate it  |O

Thats a joke of cause  ;)
But you actually have to do better than 0.01 ppm to get uncertainties less than one LSD on an 8½ digit  :-//
« Last Edit: November 21, 2017, 03:59:07 AM by bopcph »
 

Offline zhtoor

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Re: what happened to LTZ1000 stocks?
« Reply #55 on: December 04, 2017, 10:57:43 PM »
hello,

did anybody get LTZ1000's from linear, has the production line started ("ramped up") after material change?

regards.

-zia
 

Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #56 on: December 04, 2017, 11:37:51 PM »
Yes. At least we have a shipment on the way according to FedEx, due here 12/6.
« Last Edit: December 05, 2017, 12:03:01 AM by MisterDiodes »
 

Online chuckb

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Re: what happened to LTZ1000 stocks?
« Reply #57 on: December 05, 2017, 01:27:16 AM »
I got my backordered Digikey parts on Saturday. Date code 1744.
 
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Offline mimmus78

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Re: what happened to LTZ1000 stocks?
« Reply #58 on: December 05, 2017, 01:41:40 AM »
Ohh!!! I should have accepted exchange of a 732A for a LTZ1000A the week ago ...
-> Check my Store @ Ebay
-> OR my Blog @ 118volt [IT][EN]
 

Offline beanflying

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Re: what happened to LTZ1000 stocks?
« Reply #59 on: December 05, 2017, 12:08:56 PM »
I got my backordered Digikey parts on Saturday. Date code 1744.

How long ago did you order them? Seems the couple I ordered early last week were not shipped from that lot  :(

Current backorder time from Digikey is at Feb next year.........
Coffee, Food, R/C and electronics nerd in no particular order :)
 

Online chuckb

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Re: what happened to LTZ1000 stocks?
« Reply #60 on: December 05, 2017, 12:56:48 PM »
I got my backordered Digikey parts on Saturday. Date code 1744.

How long ago did you order them? Seems the couple I ordered early last week were not shipped from that lot  :(

Current backorder time from Digikey is at Feb next year.........

I ordered these 3 months ago.
 
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Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #61 on: December 06, 2017, 05:49:37 AM »
I got my backordered Digikey parts on Saturday. Date code 1744.

Current backorder time from Digikey is at Feb next year.........

That's good - that DK lead time was listed April 2018 as of a few weeks ago.   So it seems like they've shaved a couple months off the backlog.

LT says they should be able to catch up on Vref orders in Dec / Jan.

We have seen delays like this before.  A lot depends on how many devices they ship out to the big players - LT has no real economic reason to sell LTZ's in onsie-twosie quantities but it's good that they do.
 
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Offline beanflying

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Re: what happened to LTZ1000 stocks?
« Reply #62 on: December 06, 2017, 10:12:32 AM »
Will have to make do with the LM399's that arrived today as temporary playthings :) Waiting on a stash of Vishay's from Texas Components for the LTZ's and another couple of projects too.
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Offline floobydust

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Re: what happened to LTZ1000 stocks?
« Reply #63 on: December 06, 2017, 04:19:47 PM »
I got my backordered Digikey parts on Saturday. Date code 1744.
chuckb, any chance you can note country of origin on the paperwork for those parts.
 

Offline beanflying

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Re: what happened to LTZ1000 stocks?
« Reply #64 on: December 06, 2017, 04:49:54 PM »
Tried to 'order' 100 from Digikey ::)

Seems like order now you get Early Feb and ongoing looks ok at this stage.

4   2/10/2018
40   2/10/2018
56   2/15/2018
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Offline MisterDiodes

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Re: what happened to LTZ1000 stocks?
« Reply #65 on: December 07, 2017, 10:58:11 AM »
Just checked our LTZ1000A order (order direct at LT) rec'd 12/6.  Date code week 45 of 2017, diffused Milpitas CA, USA, assembled Malaysia, tested Milpitas.

Every device 100% tested at LT Milpitas, CA USA, shipped from Milpitas and every device is guaranteed to meet datasheet specs, as signed off by LT.  Certificate in the shipping package.

Everything is correct and exactly as expected.
 

Offline beanflying

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Re: what happened to LTZ1000 stocks?
« Reply #66 on: December 07, 2017, 11:01:42 AM »
I looked at buying these and a few other bits from LT direct but $90USD export freight is crazy money.
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Online chuckb

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Re: what happened to LTZ1000 stocks?
« Reply #67 on: December 08, 2017, 08:56:59 AM »
I ordered some LTZ1000As directly from Linear Tech on July 11, 2017. They arrived today. Date code 1744.
Country of Origin, Malaysia.
 
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