Author Topic: what happened to LTZ1000 stocks?  (Read 4159 times)

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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 »
 

Offline 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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Online 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]
 

Online 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.........
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Offline 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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Online 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.
 

Online 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.
 

Online 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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Offline 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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