ADR1000 Datasheet - Page 1
Forum section: electronics / general

author: vmiguel
author_rank: Newbie
timestamp: August 05, 2021, 07:30:17 pm
content: Voltnuts Rejoice!If you got you got, if not is too late

author: TimFox
author_rank: Super Contributor
timestamp: August 05, 2021, 10:57:06 pm
content: Pray, what is this ADR1000 of which you speak?

author: chuckb
author_rank: Frequent Contributor
timestamp: August 05, 2021, 11:41:00 pm
content: Feel free to share the datasheet here

author: Vgkid
author_rank: Super Contributor
timestamp: August 06, 2021, 12:05:07 am
content: I swear he had posted it, then deleted it.Here you go:

author: chuckb
author_rank: Frequent Contributor
timestamp: August 06, 2021, 12:23:17 am
content: Does anyone have samples yet?

author: chuckb
author_rank: Frequent Contributor
timestamp: August 06, 2021, 12:50:54 am
content: if the ADA4084 opamp negative power connection is grounded, it is not the best device to use with this voltage reference, When the common mode input voltage is between 0 and 0.5V the Bias current can suddenly change 200na. The offset voltage has a step change also. These effects are reduce by the gain of the internal transistors but there is no need for that instability in a precision circuit.The new voltage ref looks great!

author: branadic
author_rank: Super Contributor
timestamp: August 06, 2021, 05:51:11 am
content: Quote from: chuckb on August 06, 2021, 12:23:17 amWe have already seen first result on ithttps://www.eevblog.com/forum/metrology/lowest-drift-lowest-noise-voltage-reference/-branadic-

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2021, 06:31:09 am
content: The suggested ADA4084 is a nice OP, but likely not the best choice for the suggsted circuit. I have not found data for the low frequency current noise, but it could be a problem. The OPs see a rather high source impedance (some 60 K) and current noise thus matters.The OP is not that critical, so that the difference may not be that obvious.Chances are the classic LT1013 like in the standard LTZ1000 circuit would be the better choice.6.6 V ouput voltage mean scaling to 10 V would be a factor very close to 1.5, which could be nice.

author: tszaboo
author_rank: Super Contributor
timestamp: August 06, 2021, 09:34:47 am
content: All right, a few notes:Nice to see tempco susceptibility in the datasheet, that was something I almost had to guess from the LTZ1000's. They even put thermocouple effects in it, once again, this is great.The circuit is very similar to the LTZ1000. The end result is lower noise on paper, but the peak to peak noise is almost unchanged. The 0.2ppm tempco seems worse, but I dont think it really is in practical applications. They probably built their circuit without those hermetically sealed VPG foil resistors, as most users will.ADA4084: Probably a sales decision to put a twice as expensive opampm there, without a TI alternative. I dont blame the engineer.Quote from: Kleinstein on August 06, 2021, 06:31:09 amI was just thinking of that. Scaling 7.2V is odd, we either do PWM, or live with the issues of resistor scaling. Scaling 6.6V to 10, we can use the LT5400B and a trimmer, which is a lot cheaper than those bulk metal foil resistors with similar performance.

author: ramon
author_rank: Regular Contributor
timestamp: August 06, 2021, 11:58:15 am
content: What a sad day!Needs 10mA more than LTZ1000A for the same setting.And we still have those Kovar leads.But great day for those who stocked old chips. I regret not having bought if 100 units when they were < $46.06.

author: ramon
author_rank: Regular Contributor
timestamp: August 06, 2021, 12:12:49 pm
content: Although it could be useful for a 0.48V reference (Dual LTZ1000A - ADR1000).

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2021, 12:25:13 pm
content: The curve for the supply current is with a lower temperaure set point for the LTZ1000. Chances are this is just one example and the heater resitor on the LTZ1000 had quite loose specs. So the actual current needed for the LTZ1000A could scatter a lot, though many more can be more in the middle. At least the new heater specs are relatively tight - so the needed current is more predictable.The noise is slightly lower - though this maybe more the higher frequency noise - not clear how the very low frequency noise behaves. There is quite some scattering anyway ! For some reason they show the noise curves with the heater inactive - so this may include thermal fluctuations.The big plus is a lower TC before temperature control and thus less demand on the resistors. So the drift and TC contribution from the resistors is reduced by about a factor of 2.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 06, 2021, 12:56:04 pm
content: Thanks VgkidThere were rumors about a ADR1000-Version with integrated resistors and OPs, is that bollocks?

author: chuckb
author_rank: Frequent Contributor
timestamp: August 06, 2021, 01:14:53 pm
content: Looks like Keysight can update the 3458A A9 Vref module now and offer a 1ppm / year factory option!Two sealed Vishay BMF resistors could raise the voltage 10% to match the LTZ1000 voltage with no impact on drift.With this lower Vref noise the old LT1001 (10nV / rt Hz) amplifiers on the ADC A3 PCB could need updating. I know some good choppers they could use.The noise at the fundamental ADC frequency of 6Hz is now 1/2 of the old value. So that should help it's operation.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2021, 03:14:31 pm
content: For a direct replacement of an old LTZ1000 reference the 7-8% lower voltage may be an issue. Using resistors for gain would still add to the drift, more than the resistors at the reference directly.The drift specs are not that much different from the LTZ1000. The total circuit drift also include some contributions from the resistors - though less with the new ADR ref. Another point is that the typical value in the data-sheet are not yet that well tested. The DMM spec. numbers for the drift should also include hysteresis effects and an extra K factor of some 2 to 3 to get from typical values to expected upper limits. The logical 1st setp to better drift specs would be s slightly lower set temperature at the cost of lower maximum environmental temperature.Adaption to the lower reference voltage at the 3458 could be done at the ADC: replace the 7 to 12 V part included in U180 with 2 external resistors. The 2 resistors here don't have to be matched to the other resistors inside U180.The LT1001 OPs in the 3458 ADC are only a small part of the ADC noise and drift. For 10 PLC mode the relevant frequency would not be 6 Hz, but 3 Hz (or 2.5 Hz with 50 Hz mains) - there are a few possible modern alternatives, even without using choppers.For some reason the ADR1000 is not found easily on the analog website. So there may be a problem or delay and maybe still some change.The external OP is the least problem - an LT1013 is not that expensive and large. The weak point is the need for the external resistors (e.g. 70K, 70K, 100 Ohms, 1 K, 13 K). The caps would be very hard to integrate on a chip.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 06, 2021, 07:29:15 pm
content: It wouldnt all fit in a TO99-package, but maybe in a TO3-package like the Apex PA88https://www.richis-lab.de/images/Opamp/03x02.jpg

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2021, 08:03:12 pm
content: For many used with a relatively large temperature range the reference would run reasonable warm (like 60 C or even more). OP performance is better at low temperature.With more parts that need power the oven would also need more power. As a rule of thumb I consider oven power to be about 2 times the power of the circuit inside at least. So ideally only the parts that need the oven and are low power should be kept at temperature - other parts are better outside.A smaller circuit also makes the oven faster and this helps to keep the capacitor reasonable small without going too high in impedance.

author: The Soulman
author_rank: Super Contributor
timestamp: August 07, 2021, 10:25:43 am
content: Quote from: Kleinstein on August 06, 2021, 03:14:31 pmCouldn't find it at all on the website, did something change or am I not looking hard enough?

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: August 07, 2021, 10:53:41 am
content: Quote from: The Soulman on August 07, 2021, 10:25:43 amHello folks,The part is released but ADI will not take it to the web - something ADI rarely does.Best regardsScoobyDoo

author: The Soulman
author_rank: Super Contributor
timestamp: August 07, 2021, 10:59:26 am
content: Quote from: ScoobyDoo on August 07, 2021, 10:53:41 amInteresting, will it only be available for "selected" customers?

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: August 07, 2021, 11:13:33 am
content: Quote from: The Soulman on August 07, 2021, 10:59:26 amThe ADR1000 is intended for selected customersThe ADR1001 will probably be put online and made available through distributor channels.The ADR1001 contains all necessary resistors and HW implementation is rather easyBest regardsScoobyDoo

author: daqq
author_rank: Super Contributor
timestamp: August 07, 2021, 01:28:46 pm
content: QuoteThat's confusing. Any idea why?

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: August 07, 2021, 07:45:47 pm
content: Hello folks - the people from ADI did not divulge a rationale and so any word on this would only be pure speculation ...However the good news is that most likely the ADR1000 IC team lead will give an online presentation during MM2021 ...So you all have a good reason to attend MM2021 (Stuttgart) - ( if CoVid rules allow us ... )Best regardsScoobyDoo

author: branadic
author_rank: Super Contributor
timestamp: August 07, 2021, 08:04:21 pm
content: Damn, now you've leaked the secret surprise talk that I could organize thanks to the help of my german ADI contact!-branadic-

author: ramon
author_rank: Regular Contributor
timestamp: August 08, 2021, 12:51:04 am
content: They say on the datasheet about a "15°C of margin". So the maximum ambient temperature would be 60°C. And at that point the LTZ1000A needs just 8mA and the ADR1000 requires 22mA. That is not an improvement at all.At normal room ambient temperatures (10C to 30C) the LTZ1000A will need less than 10 mA than the ADR1000. It doesn't make any sense that you claim in the datasheet that "The ADR1000 uses a specialized epoxy die attachment to maximize the thermal isolation that reduces the power consumption required to achieve a given set temperature." but you cant beat the LTZ1000A.They also say "At an ambient temperature of 10°C, the heater power consumption is approximately 35 mA2 × 242 Ω = 300 mW".I wonder if they made a mistake and they swapped the LTZ1000A and ADR1000 curves.I need to ask, there is nothing better in 2021 for hermetic sealing than those KOVAR leads?

author: ramon
author_rank: Regular Contributor
timestamp: August 08, 2021, 01:21:10 am
content: They also said:"Increasing the current in the Zener (IBZ1) reduces the reference noise by the inverse square root of Zener current. Zener bias current above 8mA is not very practical as power dissipation limits maximum ambient temperature."They probably made a mistake and the graphs are swapped.(I guess that the curve for ADR1000 is the lower one, and that explains why they recommends 15C margin, 60C is the maximum ambient temperature allowed to regulate to a Tset of 75C. But then you are maybe right to say that theADR1000LTZ1000Ajust needs 5C margin. (Jesus, I can foresee now hordes of people stocking LTZ1000A chips!)If that is the case, then they also probably wanted to mean "At an ambient temperature of-10°C, the heater power consumption is approximately 35 mA.")

author: ramon
author_rank: Regular Contributor
timestamp: August 08, 2021, 01:34:34 am
content: Quote from: daqq on August 07, 2021, 01:28:46 pmThen, It's really a sadsadsadday. No (paid) samples option for us either?

author: ramon
author_rank: Regular Contributor
timestamp: August 08, 2021, 03:06:51 am
content: Quote from: branadic on August 07, 2021, 08:04:21 pmBut I think it better now because we can prepare many questions in advance. Someone might be probably listening, so here it goes.Question #1: What was the reason (or reasons) why ADI started this new design?A) some LTZ1000 source materials were no longer available.B) the foundry in which the LTZ1000 were done was going to close that process (or the whole foundry was to close).C) the main paying customers didn't liked anybody to be able to source this component. So they asked ADI for LTZ1000 discontinuation an paid money to create a new reference just only for them (and maybe a less performing second IC alternative for ordinary people).D) after 30 years, the original designers have described many possible improvements and they were allowed to do more R&D on this IC without any budget limit to create the new best top performing voltage reference in the world.E) after merging the management team was able to laid off all those old bearded engineers, and they assigned this task to the new young employees to have them something to distract with.F) we have no idea, management just tell us one day that we need to read the (more that one houndred pages) eevblog LTZ1000 thread, and to propose some design change with two requirements: 1) removal of 'LT' initials from the LTZ1000 and related components (LT1013); 2) keep that kovar leads and packaging because we don't have any need, money and time to mess with that problem.G) Other reasons : (tell us, please ..........................)Question #2: Why still those KOVAR leads?A) No cost/performance technical alternatives.B) We didn't have any budget to do RD on this item.C) Management/Customers didn't wanted/allowed us to do any modification.D) Other reasons : (tell us, please ..........................)Question #3: Why no stated noise graphs at oven temperature?A) Because they were awful. Please, don't tell anyone.B) Because we didn't have time or resources. And probably will never have.C) Other reasons : (tell us, please ..........................)Question #4: Why only data for Tset = 75C?A) Because this is the most stable Tset temperature.B) Because we didn't have resources to do additional testing. Also the main (paying) customer wanted this temperature, so we will not test any other temperatures.C) Other reasons : (tell us, please ..........................)Question #5: Has the pop corn noise been investigated, measured, solved?A) Pop corn noise? What is that?I have no idea what are you talking about. Please, next question.Question #6: EMI/RF issues.There have been discussion about need or not for additional capacitors on the PCB to strength the EMI/RF issues of the reference.Also there have been claims that there is a need for thick cold rolled steel enclosure (1.6mm, or even better 3mm) to keem EMI/RF issues under control.Has any testing been done about this?A) uh! That is your problem. We are just IC designers, we don't care about anything far away than those kovar leads. Also why bother?, our customers have been 30 years handling this issue, and they still buy our chips.B) That would take a lot of time and will cost a lot of money. Do it yourself.C) I will tell you a secret, but please don't say anyone. Let me tell you a story about the 'Crystal Lattice' ... (Edwin, Digilentminds we really miss you!)D) Other reasons : (tell us, please ..........................)Question #7: Did SMD, hybrid or ceramic packaging crossed your minds?A) Why? We are lazy. And who is going to pay that? Common FR4 PCB has been used for more than 30 years.B) We dreamed about that and even talked a few times during launch, in that PCB layout only 4 or 5 components need tightly thermal stability so it would make sense to have ADR1000, R1, R4, R5 on a smaller (cheaper) Aluminium oxide or AlN ceramic board as inner-most oven to keep constant temperature and prevent issues with those Kovar leads. And all other components on normal FR4 PCB ... but Management/Customers didn't wanted/allowed us to do any modification....

author: Kleinstein
author_rank: Super Contributor
timestamp: August 08, 2021, 06:08:14 am
content: For the current consumption, much of the difference between the 2 curves is from a different set temperature. The one with the higher consumption runs hotter and also seems to work to a correspondingly higher temperature. So to compare one should shift one curve by some 12 K (the difference is max working temperature). These look like curves for just 2 units. The heater resistance in the LTZ1000 has quite some tolerance (200-420 Ohms) and the needed heater current scales like 1/sqrt(R_heater). So it could be just a different heater resistance.The ADR10000 has a heater resistance spec. quite a bit narrower and more to the lower end of the values. So it is normal to expect a little more current, but also less scattering and the worst case current (lowest resistance) is lower.The difference to the LTZ1000 is quite small - not really a new design. It could be as little as a slightly different doping level to get the lower voltage and naturally a shift in the Zener TC (which results in the reduced unheated TC). Slightly less noise at a lower voltage is also not such a surprise. In the extremes this could be just a batch that got a bit off center and ended up with slightly different properties.Chances are they could offer the LTZ1000A and ADR1000 in parallel - some meters are designed for the higher voltage. It should not be so hard to produce bother versions.

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: August 08, 2021, 08:16:31 am
content: The ADR1000 and LTZ1000(A) will co-exist on the market - but the ADR1000 is for sure the better part and there is more to come - certain things (roadmap, ... ) are still under NDA ...Feel free to list technical (related) questions in this post - so ADI team can answer (technical) questions during MM2021 event.Stay tuned ... welcome to MM2021 summit.Best regardsScoobyDoo

author: ramon
author_rank: Regular Contributor
timestamp: August 08, 2021, 08:21:20 am
content: Quote from: Kleinstein on August 08, 2021, 06:08:14 amThey don't say that:"Figure 6. Total Supply Current vs. Ambient Temperature,TSET = 75°C"Nowhere in the datasheet they say that the graphs are for different TSET point.And why on earth would they (or we) want a comparison graph with different temperarure settings?

author: Kleinstein
author_rank: Super Contributor
timestamp: August 08, 2021, 08:41:40 am
content: The 2 power curves show quite a difference in the temperature where the current goes down to a low value when the heater turn off. This is at some 62 C for the lower power one and some 74 C for the higher power one. The useful maxium ambient would be something like 10-15 K lower. So even if the nominal set temperature after some tables may be 75 C. The actual values are obviously different.The current consumption also depends on the rest of the circuit. The AD4084 is a little more power hungry than the LT1013. The position of the transistor for heater control can also have an effect. If close to the reference the power from the transitor can contribute - if done right this may even help with the overall TC.With a higher resistance for the heater, the LTZ1000 would need a higher supply voltage for the heater, though tyically less current. The rather large range for the LTZ1000 heater resistor requires a relatively high voltage (in case the resistance is high) and a high current capability (in case the resistor is at the low end).One could argue a little that a precision application would likely have a 15 V or similar supply anyway. So a little higher resistance may have been better, but the tighter tolerance definitely helps.

author: openloop
author_rank: Regular Contributor
timestamp: August 27, 2021, 12:00:05 pm
content: I kind of get why they kept Kovar leads. It's not just budget for exploring alternatives. It's time. My understanding is that there are no alternatives that had the same amount of testing in the field. We talking tens of years (untold thousands if combined) of thermal cycling and whatnots.If thermocoupling is a significant problem for a particular design - why not simply install a thermal short between pins 3 and 7? Like one of those thermawicks from Vishay?Same for R1 and R4/R5 (if not array'd)Funny thing about those - when manually soldering touching one end with soldering iron - other end melts too.

author: guenthert
author_rank: Frequent Contributor
timestamp: August 27, 2021, 05:13:09 pm
content: Quote from: ramon on August 06, 2021, 11:58:15 amIs here someone who did? I'm still short of a LTZ1000 for my reference (got the resistor set and somewhere one of Brandic's boards). I gladly buy one of those now obsolete chips from you.But back on topic, me too would like to see a multi-function integrated solution like the AD687. The ones in CERDIP performed quite well.

author: iMo
author_rank: Super Contributor
timestamp: August 28, 2021, 09:26:26 am
content: We need a die shot!!

author: Kleinstein
author_rank: Super Contributor
timestamp: August 28, 2021, 12:07:45 pm
content: Quote from: imo on August 28, 2021, 09:26:26 amThis would probably not be much different from the LTZ1000 die. It could be as little as slightly different doping levels and still the same masks as with the LTZ1000.

author: magic
author_rank: Super Contributor
timestamp: August 28, 2021, 01:15:51 pm
content: Probably they couldn't resist changing at least the metal and buried layer near the heater pads

author: branadic
author_rank: Super Contributor
timestamp: August 28, 2021, 01:20:44 pm
content: We will probably hear about history of ADR1000 at MM2021, but rumor says developement started long before ADI aquired LT. So we can expect some difference I guess.-branadic-

author: Andreas
author_rank: Super Contributor
timestamp: August 28, 2021, 05:32:52 pm
content: Hello,I hope they did not change too much on the imho optimized design.Otherwise we could get some drift by tilting the device similar to the LM399 chip.with best regardsAndreas

author: dietert1
author_rank: Super Contributor
timestamp: August 29, 2021, 10:59:57 am
content: One problem with the LM399 is the loose thermal cover. I think its movements may be the reason both for popcorn noise and positional dependence. One mechanism may be a minute temperature change, but i can't tell any numbers like the LM399 TC at its operating temperature. Anyway, i am operating 15 LM399 right now, all with fixed thermal covers and no popcorn noise observed. Last week i turned around a board with 10x LM399 to mount it "heads down" because i want whatever "dirt" may be inside to stay away from the silicon.Sooner or later noopy will get an ADR1000 and show us the die to put an end to speculation. My guess would be: Four zeners => half the noise.Regards, Dieter

author: magic
author_rank: Super Contributor
timestamp: August 29, 2021, 12:32:17 pm
content: How sensitive is the LM399 to orientation? I think it could be not as much a matter of absolute temperature as thermal gradients. Quite obviously, each 1mK mismatch between the zener and its compensation transistor is guaranteed 2µV change in output voltage. Extrapolating to a linear gradient across the whole device, it would be perhaps 10mK across the die and, dunno, maybe hundreds of mK across the can - hard to tell due to different shape and less conductive material. Not sure if airflow or the thermal cover could cause that, but if they can then your answer may be here...LTZ places critical components concentrically in the dead center of the die. Everything in it is concentric, actually.My guess: AD logo, ditched the unused inner heaters to make space for the rumored ADR1001 scaling resistors, maybe increased diode diameter if you insist on that. And all else invisible.

author: Andreas
author_rank: Super Contributor
timestamp: August 29, 2021, 08:58:35 pm
content: Quote from: magic on August 29, 2021, 12:32:17 pmSome results are here:https://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/msg360779/#msg360779It mainly depends on (additional) thermal isolation of the LM399. And of course of the individual reference itself.with best regardsAndreas

author: magic
author_rank: Super Contributor
timestamp: August 29, 2021, 10:50:07 pm
content: Interesting, the effect is quite clear. But the cause must be something else than I thought, because polarity of change is opposite to what was expected. Nevertheless, the worst cases 1/3 correspond to the die being oriented "sideways", with the heater on the left/right respectively (top view).editUnless there is some reason why the top-facing side of the can is cooler than the lower side.

author: iMo
author_rank: Super Contributor
timestamp: August 30, 2021, 08:01:04 am
content: The 399 chip is of highly asymmetric design - and the gas molecules still have a lot of space inside its package to change their flows around the die.. Unless the phonons in the die lattice are affected by the gravity too..PS: also the bonding wires could create a different force at the die based on their orientation in the gravity field. With an asymmetric design it may play a role. Like with crystals - while changing orientation of an ocxo (for example) you may easily see a frequency change..Edit: added "chip" after "399"

author: branadic
author_rank: Super Contributor
timestamp: August 30, 2021, 08:08:12 am
content: Every reference containing an integrated heater is somewhat sensitive to tilting. The principle is also used in thermal inclination sensors. Think of a candle, that likes to straighten its flame upwards. Even if the buried zener is surrounded by the heater there will be a small change in temperature. Having the zener adjusted to z.t.c. will however surpress the effect.-branadic-

author: bsdphk
author_rank: Regular Contributor
timestamp: August 30, 2021, 08:54:17 am
content: Quote from: imo on August 30, 2021, 08:01:04 amI always assumed that the majority of the orientation sensitivity was the insulating plastic-cap shifting around ?

author: iMo
author_rank: Super Contributor
timestamp: August 30, 2021, 09:01:53 am
content: Quote from: bsdphk on August 30, 2021, 08:54:17 am"The 399 [meaning the components on the chip/die] is of highly asymmetric design.."

author: magic
author_rank: Super Contributor
timestamp: August 30, 2021, 09:06:24 am
content: If the plastic cover is loose and rests only on the upward-facing side of the can then it may cool that side and produce a thermal gradient across the package and the die inside. My theory of thermal mistracking between Q3 and Q13 actually works in such case.Zero TC helps if the temperature regulation transistor is at a different temperature than the reference.Nothing can save you if the diode and transistor which constitute the reference itself are at different temperatures from each other. That's where all the non-LTZ devices cut corners to a varying degree.Worse still, even a perfectly symmetric individual diode could be affected by gradients because areas at different temperature will operate at slightly different current densities.

author: iMo
author_rank: Super Contributor
timestamp: August 30, 2021, 09:28:53 am
content: Quote from: imo on August 30, 2021, 08:01:04 amWikipedia:QuoteThe next ADR2000 revision may contain a "heat pump". The phonons could be pumped by help of an electric field into a specific direction, imho.

author: bsdphk
author_rank: Regular Contributor
timestamp: August 31, 2021, 06:00:16 am
content: Quote from: imo on August 30, 2021, 09:01:53 amYes, I know that, and provided the thermodynamic circumstances of the metal can are constant, I am sure that will cause some measurable amount of orientation sensitivity.But they are not constant, on all the LM399's I have had my hands om, the plastic cap can move relative to the pins, and that means a huge difference in thermal conductivity between the metal can and the plastic insulation.So by all means attempt to characterize the orientation sensitivity of the chip design, but do so only after you either glue the plastic cap to the metal can or remove it entirely.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 31, 2021, 07:02:39 am
content: The movement of the plastic cap is a good point. Instead of glue I would consider a little bit of cotton wool or similar to keep it in a fixed position.The can itself is relatively small and there is little temperature difference inside. So I don't think convection inside the case is an issue.

author: bsdphk
author_rank: Regular Contributor
timestamp: August 31, 2021, 09:47:24 am
content: Quote from: Kleinstein on August 31, 2021, 07:02:39 amMy preference would be to get rid of it entirely, because it does the wrong thing for what we're trying to achieve.And yes, that is one of my pet peves: Metrology people tend to think in terms of thermal conductivity when they should focus on thermal impedance, so let me explain:Thermal insulation = "Unwillingness to move thermal energy" = Porous low thermal capacity material which restricts the movement of gas molecules. Example materials: EPS foam, "RockWool" and knitted sweaters.Thermal impedance = "Unwillingness to change temperature" = Solid high thermal capacity with low(-ish) thermal conductivity. Example materials: Non-crystaline rocks, bricks & concrete.The benefit of high thermal impedance is that temperatures changes propagate very slowly through the material, around 25kg of granite will get you into microkelvin territory.The downside is that it can therefore take weeks or months to reach that thermal equilibrium.If you want to experiment: Sandwich your PCB between a couple of candlelight holders made from granite, concrete or mable.

author: mzzj
author_rank: Super Contributor
timestamp: August 31, 2021, 11:17:55 am
content: Quote from: bsdphk on August 31, 2021, 09:47:24 amAdd paraffin wax and some plastics to your list. Higher specific heat capacity than granite and lower thermal conductivity.

author: magic
author_rank: Super Contributor
timestamp: August 31, 2021, 12:26:41 pm
content: Quote from: bsdphk on August 31, 2021, 06:00:16 amMore like: solder thin copper twisted pairs for zener sense, zener force and heater power (bonus: kovar cables with solderless joints). Place in the middle of a copper pipe and flood with polyurethane foam, surround with another layer of insulation. Then you may have some excuse to blame the remaining effect on air flow or dust inside the can.Otherwise, external air and PCB are likely to have more effect.

author: ramon
author_rank: Regular Contributor
timestamp: August 31, 2021, 02:21:48 pm
content: No PU foam inside, MgO powder. Low electrical conductivity, high thermal conductivity to avoid issues with kovar. Both Over the pcb and under the pcb too.Once the above is done, then the thermal insulation. PU or whatever you like. Then do the tilting test again, and you now that this can only be the effect of internal die issues.Edit: no need to say, that all of the above, without the plastic case.

author: bsdphk
author_rank: Regular Contributor
timestamp: August 31, 2021, 04:30:04 pm
content: Quote from: magic on August 31, 2021, 12:26:41 pmNo, no & no.See above re: Thermal impedance

author: bsdphk
author_rank: Regular Contributor
timestamp: August 31, 2021, 05:02:19 pm
content: Quote from: mzzj on August 31, 2021, 11:17:55 amYes, there are some plastics in the right ballpark, and yes they are much easier to work, but polymers as a rule, cannot be bought in a usable shape.You can get them as pipes, sticks, granules, sheets, foils, tapes, but not as a solid 5cm cube.If you find something 5cm thick, it is likely to be at least 40cm on the two other dimensions, and weigh so much the postman will hate you forever.(Cutting 5cm thick polymer takes a really good wide-toothed high-speed circular saw. Too low speed or too thin-toothed and the friction will melt the polymer and your saw will get stuck. Do not ask me how I know this :-)All that said: Any lump of high density polymer (HDPE, ABS etc.) will give more stable temperature than what we usually see on pictures here.But ask your wife first: There is 22% chance she have a pair of geologic candlelight holders she never uses.

author: chris_11
author_rank: Contributor
timestamp: September 15, 2021, 05:49:51 pm
content: The issue with the covers is much more the prevention of thermal flow variations than pure isolation. Even a thin heat-shrink cover over the Kovar leads and package will do. Thermal air movement will create noise through low frequency temperature changes in the Kovar leads, which have about 40uV/K to copper similar to lead/tin to copper. Check low frequency performance on a LT1000 without a cover. Then test a simple heat shrink tube (no need to shrink) just cover the leads and package.The lattice is heated and on constant high temperature. The PCB is on a lower temperature, so a thermal gradient is always present. Voltage variation equal to 1/f noise is created when the thermal gradient over the leads varies with air movement.BRChristian

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: September 16, 2021, 09:08:36 pm
content: Hello folksThe ADR1000AHZ is now available from the ADI online webshop.The MOQ has been set as low as 5 (one) to reach all Voltnuts - (MOQ = 5).The part will be monitored for a period of at least six months to understand if this is a viable (sustainable) path for ADI - so pls. order as much as you can ...ADI is checking this MPN in order to understand if ordering process goes smoothly and will remove existing issues with this MPN = ADR1000AHZBest regardsScoobyDoo

author: Echo88
author_rank: Frequent Contributor
timestamp: September 17, 2021, 04:44:33 pm
content: Is the AD7177-2 capable of using the ADR1000AHZ directly for its Refinput?The maximum ratings for the AD7177-2 state:AVDD1, AVDD2 to AVSS: −0.3 V to +6.5 VReference Input Voltage to AVSS: −0.3 V to AVDD1 + 0.3 VSo i would have guessed the Refinput accepts 6.8Vmax in at AVDD1 = 6.5V, suitable for a max 6.67V from a ADR1000AHZ.Or is it foolish of me to think that might work due to substrate diodes starting to conduct/other reason?https://www.analog.com/media/en/technical-documentation/data-sheets/AD7177-2.pdf

author: razvan784
author_rank: Regular Contributor
timestamp: September 17, 2021, 06:34:39 pm
content: It's not wise to run chips at their maximum ratings, nor for the inputs to exceed the supplies.What I would do is divide down the reference to something like 6V and use that as both the supply (through a power buffer of course) and reference input.Dividing 6.6V to 6V will attenuate the error due to the drift of the divider approximately 10 times, as discussed by Dr. Frank in the LTZ thread.You can use a thin-film array as indicated by John Pickering and as discussed in the Statistical Arrays thread.The recent paper by N. Beev also linked on this forum indicates the low-noise types (TDP, NOMC etc)

author: magic
author_rank: Super Contributor
timestamp: September 17, 2021, 06:40:36 pm
content: These are stress ratings only, operation is not implied, blah blah...They specify reference input range as 50mV beyond the rails, assuming you aren't using the internal buffer of course. What's beyond 50mV? Dragons... maybe OK at 25°C, maybe not.

author: TiN
author_rank: Super Contributor
timestamp: September 19, 2021, 07:23:31 am
content: Thermal image of bare chip during 2 minute operation. Hottest point is die epoxy attach. Die itself looks cooler due to different emissivity and reflection parameters. Resistors for heater are 11.5kOhm/1 kOhm, zener current 4.05mA (120 Ohm).

author: chris_11
author_rank: Contributor
timestamp: September 19, 2021, 08:57:41 am
content: Quote from: magic on September 17, 2021, 06:40:36 pmIn CMOS circuits you inject substrate or well currents if you go under the lowest -supply or above the +supply, unless there are special additional structures used. Typical there are diodes similar to a FET Body diode and/or. ESD structures with similar effect. So 50mV will be o.k. since you do not get significant currents. But for sensitive applications even 300mV might be to much and there are always spikes from noise etc. So do not exceed the supply boundaries on any input unless the data sheet explicit allows for that.If in doubt, check with a nA meter at what point currents starts to flow.BRChristian

author: chris_11
author_rank: Contributor
timestamp: September 19, 2021, 09:00:38 am
content: Quote from: TiN on September 19, 2021, 07:23:31 amIs that a cut open TO package from the top or how did you make the image?

author: magic
author_rank: Super Contributor
timestamp: September 19, 2021, 09:12:37 am
content: Definitely looks like that. The orange rings are glass seals around pins and you can also see where is the pin connected to the can. The image shows thermal emissivity of the various components first and foremostbut temperature differences between identical materials may be comparable.Quote from: chris_11 on September 19, 2021, 08:57:41 amIt's worse than that, because D-S ADCs sample and hold the input in some internal capacitors which are switched by means of MOSFETs, so there is likely leakage from those capacitors too if their potential forward biases the body diodes.

author: iMo
author_rank: Super Contributor
timestamp: September 19, 2021, 11:39:14 am
content: Btw, why the glass seals are 12C higher than the surrounding metal?It looks to me like "the Blackbird vehicle faster than the tail wind" problem..

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2021, 12:45:46 pm
content: The reference has an essentially constant temperature. Nearly all the details visible is a diffenrence in the emissivity. So the picture is not eally showing temperature, but more like optical properties in the IR range, more like a normal photo, just in the IR.

author: KT88
author_rank: Frequent Contributor
timestamp: September 19, 2021, 01:25:55 pm
content: QuoteThe answer is a clear NO.The (operating-) specs are stated for 4.5 to 5.5V. Anything outside that values is not covered by the specs.There is an abs. voltage spec for the external reference (Vref = (Ref+) - (Ref-)) which is AVSS (min) to AVDD1 (max) with buffers enabled and AVSS-0,05V (min) to AVDD +0.05V (max) with buffers disabled.Abs. maximum ratings only state what a chip can survive.CheersAndreas

author: rigrunner
author_rank: Frequent Contributor
timestamp: September 19, 2021, 05:11:58 pm
content: Quote from: TiN on September 19, 2021, 07:23:31 amHow are you deriving 4.05mA at 120Ohm?If I plug the numbers into the formula on page 7 of the data sheet I get a slightly different figure.11K5/1k heater should give 51.265 C die temperature.Using the R1= 0.658V-0.0022*51.265 over 4.05mA minus 7 Ohms R1 resolves to 127.62 Ohms.To get 120 Ohms R1 with the same heater value I need 4.29mA.I'd like to understand where I'm going wrong with the data sheet calculation

author: TiN
author_rank: Super Contributor
timestamp: September 19, 2021, 05:25:01 pm
content: I felt like formula on page 7 slightly wrong, as there are 7 ohms in series were lost and they used 0.0022 in one spot, but 0.002 in other.Actual heater set was 11.435/1k (13kOhm + 95kOhm in parallel), so bit different. I'd also think removed cap would affect temperature quite a bit due to no protection from air drafts/heat loss outside.That imagery is more of entertainment value, not metrology value.

author: rigrunner
author_rank: Frequent Contributor
timestamp: September 19, 2021, 05:42:58 pm
content: Quote from: TiN on September 19, 2021, 05:25:01 pmThe example in the data sheet is also wrong in that it doesn't appear to subtract the 7 Ohms. The 129.5 Ohm example result should be 119 Ohm (using the .0022)Quote from: TiN on September 19, 2021, 05:25:01 pmIt's pretty

author: d-smes
author_rank: Regular Contributor
timestamp: September 21, 2021, 08:39:57 am
content: The datasheet refers to a "recommended layout" on page 1 but none is given. Is there other documentation that shows this recommended layout?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: September 29, 2021, 10:56:22 pm
content: Quote from: bsdphk on August 31, 2021, 05:02:19 pmWhat?Foam isn't that difficult to source. Here is an 8x8x8 inch^3 polyurethane cube for example:https://www.mcmaster.com/8882K16/As for cutting... please don't use a power saw. Instead, use something like a (hot) knife and cut manually:Tip: If you use a hot knife (or a cheap soldering iron), do not keep it in one position too long or you might start a fire

author: bsdphk
author_rank: Regular Contributor
timestamp: September 30, 2021, 06:09:39 am
content: Foam will only give you high thermal resistance (= bad conduction), you need a solid to get high thermal impedance (= resistance to change).

author: wutieru
author_rank: Contributor
timestamp: September 30, 2021, 10:59:11 am
content: The day before Chinese National Day, I received a gift from ADI.[imghttp://]

author: wolfy007
author_rank: Frequent Contributor
timestamp: September 30, 2021, 02:13:09 pm
content: hmmm date code 2108, thats two people with the later date code

author: eplpwr
author_rank: Regular Contributor
timestamp: September 30, 2021, 07:33:26 pm
content: Quote from: wolfy007 on September 30, 2021, 02:13:09 pmMake that three. Got delivery today of 10 pcs w/ DC 2108.

author: r6502
author_rank: Regular Contributor
timestamp: December 20, 2021, 06:36:40 am
content: Quote from: Vgkid on August 06, 2021, 12:05:07 amHello all,I just found this topic. Very interesting, also the linked datasheet is marked as "confidential", and actual it is not to find non the Analog web side.On the 1st page of the datasheet, "Table 1. Related Products", the new ADR1399 is also not linked. In the ADR1399 datasheet there is also no link to the new ADR1000 ...Does somebody have an idea where to get samples of the new ADR1000a?Guido