AD587LQ - Page 1
Forum section: electronics / general

author: eurofox
author_rank: Unknown
timestamp: April 19, 2018, 02:38:46 pm
content: Normally not available anymoreThis ic was used in the venerable Geller lab SVR-T in ceramic version.But I order 5 IC's from Aliexpress, I don't no if they are new, used, fake but I'll take the risk since it is cheapeurofox

author: cellularmitosis
author_rank: Unknown
timestamp: April 19, 2018, 03:31:06 pm
content: I took a similar risk on a few LQ's from taobao. I plugged them into my old Geller Labs reference board and they seemed to be wandering around. I intend to take a closer look at them soon but it appears they could be fake or have been damaged.However, the AD586LQ's I ordered don't seem to be wandering, so maybe it wasn't totally a bust?Good luck!

author: Andreas
author_rank: Super Contributor
timestamp: April 19, 2018, 06:52:48 pm
content: Quote from: eurofox on April 19, 2018, 02:38:46 pmI hope it is worth the effort that you need to distinguish them from being genuine.Some tips for quick checks:- test the 1/f noise (perhaps they have sold a bandgap reference which has a factor 3-5 more noise).- test the pin voltages (especially pin 8 the internal divided reference voltage and pin 3 which is usually the temperature output pin on cheaper band gaps).I personally do not believe that you can get genuine unobtanium devices.with best regardsAndreas

author: eurofox
author_rank: Unknown
timestamp: May 23, 2018, 02:34:08 pm
content: Got from Aliexpress the messageI think the guy who try to sell this did not finally manage to get some of those litlle bad boy'sBut I found a company that can supply them, after 4 weeks delay .......I will check them, they look genuine and it they are good I will post the place

author: Kosmic
author_rank: Super Contributor
timestamp: May 23, 2018, 03:45:07 pm
content: I'm looking at the specs and I don't see a lot of difference between AD587L and AD587U.If the L version is not available anymore why not simply use the U version ?

author: eurofox
author_rank: Unknown
timestamp: May 23, 2018, 03:52:48 pm
content: Quote from: Kosmic on May 23, 2018, 03:45:07 pmYou should read thishttps://www.eevblog.com/forum/testgear/geller-labs-svr-and-svr-t/50/

author: Kosmic
author_rank: Super Contributor
timestamp: May 23, 2018, 04:11:00 pm
content: Quote from: eurofox on May 23, 2018, 03:52:48 pmHo ok, I understand now

author: GigaJoe
author_rank: Frequent Contributor
timestamp: May 23, 2018, 08:51:17 pm
content: seen some for $20 ... kinda expensive.is my understanding correct, a letter just a thermal instability, or something more? (excluding items with wide range of temperature where manufacturing process may differ) means it just more effort for thermo compensating circuit?

author: Andreas
author_rank: Super Contributor
timestamp: May 23, 2018, 09:40:24 pm
content: Hello,its either better selection for T.C. or better trimming.But it is always a "average T.C." for the whole specified temperature range.(measured at 3 temperatures: min, 25 deg C, and max of specified range e.g. 0..70 deg C or -55..125 deg C)So if you use the device near room temperature the letter (grade) may be not helpful in all cases.with best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 17, 2018, 03:18:23 am
content: https://www.aliexpress.com/item/-/32881073708.htmlgot 6 reclaimed, mfg year 94, 95,91,04. all good, "philippines" on the back ...drifting, stability etc - unknown ...UPD: Seller started to ship relabeling chips ....

author: MiDi
author_rank: Frequent Contributor
timestamp: September 26, 2018, 08:23:06 pm
content: Quote from: eurofox on May 23, 2018, 02:34:08 pmAny results so far?

author: Andreas
author_rank: Super Contributor
timestamp: September 26, 2018, 09:58:35 pm
content: Hello,Quote from: MiDi on September 26, 2018, 08:23:06 pmMy preliminary results:I have ordered 2 times (8 pcs each) from GigaJoe s seller.https://www.eevblog.com/forum/metrology/ad587lq-from-aliexpress/msg1677863/#msg1677863He needed both times 1-2 weeks until I could see in the tracking system that he had sent them out.When I asked him for delivery he answered something like he wanted to find the best source for me.So obviously the seller does not have them on stock: so quality may vary.Each reference has a different date code.Devices are desoldered with partly bent pins.Output voltage on all 16 devices is within +/-3 mV from 10V. So even with ageing within 5mV datasheet spec.Pin 3 shows 0 V (so no temperature output signal like on some band-gaps)Pin 8 and pin 5 are around 7V so obviously it is a buried zener reference.1/f noise is around 4uVpp.up to now 2 devices have frequently (every few seconds) popcorn noise. (but have not evaluated all data up to now).It seems that the popcorn candidates had been marked with a black dot.On the first batch I thought that it was some flux residue from desoldering so I had removed it.On the 2nd batch I can correlate the marked device with the popcorn noise.T.C. is still under evaluation.Measured 12 devices up to now with < 2.5 ppm/K over +/-15 deg C span around room temperature.2 devices showed up to 2-4 ppm (ageing) drift during T.C. measurement.with best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: September 26, 2018, 11:24:09 pm
content: so, not bad in overall ...my batch was send immediately ... ; no any labelshaven't able to test it,one chip has strange output on pin 8 , like 1.$&% and up to 5V if heat it up ... aside of that pretty normal ...and 1 completely fried. I can not tell it from this batch or anotherJQ no LQ as described:https://www.aliexpress.com/item/-/32832885977.htmlplastic mostly fake .. don't even look at ... they actually do 10V output but nothing on pin-8 (even TC reasonable)

author: MiDi
author_rank: Frequent Contributor
timestamp: September 27, 2018, 06:13:20 am
content: Andreas, you now have new nickname (at least for me): the machine

author: MiDi
author_rank: Frequent Contributor
timestamp: October 21, 2018, 01:10:03 pm
content: 10 pcs arrived yesterday fromGigaJoe:

author: branadic
author_rank: Super Contributor
timestamp: October 21, 2018, 02:13:32 pm
content: Looks like reference from 9540 has a crack?-branadic-

author: MiDi
author_rank: Frequent Contributor
timestamp: October 21, 2018, 02:42:02 pm
content: No, it is something like epoxy, hard and very sticky - could not scratch it away with fingernails.

author: Andreas
author_rank: Super Contributor
timestamp: October 21, 2018, 05:35:41 pm
content: Quote from: Andreas on September 26, 2018, 09:58:35 pmUpdate.I examined one of the drifters more in detail.Result: still about 1-2 ppm drift during one temperature cycle (15 hours).So I think the two "drifters" will not be usable for my 10V references.with best regardsAndreas

author: MiDi
author_rank: Frequent Contributor
timestamp: October 23, 2018, 06:30:27 pm
content: 6 came DOA, 4 are very good within specs (worst is +2mV, best -0.5mV).Seller refunded 6 pcs. immediatly.

author: syau
author_rank: Frequent Contributor
timestamp: October 24, 2018, 09:55:31 am
content: Received my batch of shipment this Monday, 3 out of 10 DOA. The remaining 7 all within specification which the best one is only +2ppm

author: Macbeth
author_rank: Super Contributor
timestamp: November 10, 2018, 02:58:03 pm
content: Ordered 6 from GigaJoes seller on 21/10 and received today. One is a dud, of the rest worst is +1.9mV, best +0.4mV. All CERDIP random dates.

author: WillTurner
author_rank: Regular Contributor
timestamp: November 23, 2018, 05:08:01 am
content: Voltage measurements of six parts from vendor LING LI "Shop1476012 Store" tested 28Aug18.Datecode Vtrim Vout Notes9144 7.22 10.019331 7.04 14.16 Bad9816 13.91 14.34 Bad9825 6 to 6.5 10.01 Vtrim unstable. Bad0016 1.5 14.46 Bad0422 7.06 10.01Hence, at least four bad out of six parts. Note that I am not implying in any way that the remaining two parts are "good".I sent the above information to the vendor, and their response was "Sorry, if the test does not pass, you should consider buying, because these ICs have been discontinued for a long time, and the market is also out of stock."Based on the above, I could not recommend buying these. The AD587JQ through a trusted supply chain, and selection for tempco seems a better bet.

author: Andreas
author_rank: Super Contributor
timestamp: November 23, 2018, 08:36:56 pm
content: Hello,with 20 brand new parts from DigiKey AD587JQ I had only 3 partswith less than 2 ppm/K and less than 5(6)uVpp popcorn noise.(ok 5 other parts were not far away but the rest completely useless for my needs).And even then you can have large drift (more than 2 ppm/year after 5 kHrs)after pre-selection.At least those parts seem to be only mis-used and recycled parts. (and no fakes).I already had some parts labeled MAX6350 in CERDIP which were definitively no buried zeners.So buying such parts from a non official source is always a bit of gambling.And in every case you need the equipment for noise and drift tests.With best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: November 24, 2018, 06:18:10 pm
content: Does only AD587 has PIN-8 as an output from zener ? and no others in CDIP8 has it ? Reason why I'm asking, got relabeled AD587, but I'm suspicious it really 587 just a letters are relabeled.last year bought got JQ (as pictured), not LQ ; seller are reluctant to talk ...https://www.aliexpress.com/item/-/32832885977.html

author: Andreas
author_rank: Super Contributor
timestamp: November 24, 2018, 06:47:44 pm
content: Hello,Ref102 also has pin 8 as noise reduction input. (SO-8)VRE310 also noise reduction on Pin 8.Some other (5V) references on Pin 3.What makes you shure that there are no re-packaged components.From SO8 to CERDIP?I always check Pin 3, Pin 5 and Pin 8 for suspicious voltages on unknown references.with best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: November 24, 2018, 07:27:31 pm
content: the back has a Philippines and date-stamp and code similar to ADSerious ? are you believe in repackage soic to ceramic ?

author: Andreas
author_rank: Super Contributor
timestamp: November 24, 2018, 08:37:31 pm
content: Hello,in the mean time I think: ALL is possible.I have here "genuine" MAX6350MJAThe numbers are printed (and not laser marked as those from MAXIM).Bottom markings laser marked (PHILIPPINES and some N-Numbers typical for LT-parts)The sealing between the ceramic discs is not opaque like glass.It is grey like cement.Noise is a factor higher than on a buried zener. So more like a band gap reference.On Pin 3 I measure a temperature dependant signal like on a band gap.My best guess: some Ref02 re-marked/re-packaged to a MAX6350.with best regardsAndreas

author: iMo
author_rank: Super Contributor
timestamp: November 24, 2018, 10:13:38 pm
content: IMO, nobody in the world will re-package chips from a package A to an different B package, and sell them for a few bugs on ebay. It may easily happen the already packaged chips were stolen directly at the manufacturer's site before the labeling process, and then re-labeled in someone's cellar..Another option is to steal the entire Si wafer and to package the chips at a different manufacturing site (or well equipped cellar), and then label them, sure..

author: GigaJoe
author_rank: Frequent Contributor
timestamp: November 25, 2018, 03:57:05 pm
content: ok .... another questions:If I'd like to averaging from a 4-8 chips, what would be a reasonable way to adjust output ?like to all chips hook per var. resistor - adj. every one ; and for one only as external ?(all broad inside thermostat )and cap for noise canceling, 1uf or 100uf - is it a reasonably efficient ?

author: Andreas
author_rank: Super Contributor
timestamp: December 02, 2018, 10:08:11 pm
content: Quote from: WillTurner on November 23, 2018, 05:08:01 amHello,I fear you are right. It seems that the "good parts" are mostly gone.I got my running order (a batch of 10) from 11.11. this week end.A quick check.visual inspection:9 devices with date code 9702 -> smells like fakes: previous batches were each with different date code.1 device with date code 9731hermetically sealing is light grey (like cement) and not opaque like glass as on the previous batches (the one in the socket) -> not a good sign tooelectrical tests (voltages and noise)3 devices were completely dead: no current consumption, no backward diode between pin 4 (GND) and pin 2 (VCC).From those 1 had a broken leg on pin 4 (Gnd). And on one device a (internal) short between Pin 1 + Pin 2.1 device measured around 5 V instead of 10 V. (so it seems they have packaged a AD586 into the AD587 package).From the remaining 6 devices:1 with excessive 1/f-noise (90 - 100 uVpp instead of typical 4 uVpp) additionally a broken leg on pin 5 (adjust)1 with excessive and frequent (all few seconds) popcorn noise of nearly 20 uV1 with around 10 uV (still in evaluation) popcorn noise all 1-5 minutes.so three out of 10 seem to behave normal regarding output voltage and noise.But I have not tested T.C. and ageing drift up to now...with best regardsAndreas

author: Andreas
author_rank: Super Contributor
timestamp: December 02, 2018, 10:13:40 pm
content: Quote from: GigaJoe on November 25, 2018, 03:57:05 pmdo not have experience with averaging. But I would keep the individual cell voltages equal to keep equalizing currents near zero.100 uF as foil capacitor or as electrolytic (which has leakage currents and thus generates additional noise).And where do you want to put the cap for noise canceling.If you want to filter noise below 10 Hz (1/f noise) then it gets really hard.So the only thing you can effectively filter is wideband noise (above 10 Hz).with best regardsAndreas

author: MiDi
author_rank: Frequent Contributor
timestamp: December 03, 2018, 12:46:10 am
content: Same here, order from 2018-10-23, all 10 same datecodes and on bottom different markings.So it seems these are not genuine anymore, details follow...

author: GigaJoe
author_rank: Frequent Contributor
timestamp: December 03, 2018, 03:38:42 am
content: Interesting ... a diff source but the same black dye relabeling, it seems a single source for all diff. sellers on Ali.Usually, if such thing happens, I simply wipe by acetone 2 chips, make a picture of sanding traces, fake relabeling , and open complain for a full refunding ... it usually works.

author: syau
author_rank: Frequent Contributor
timestamp: December 03, 2018, 07:18:19 am
content: Found hermetically sealing in my batch also light grey (like cement)but the last row of the marking (ie the row below the date code, always start with alpha follow with few digits) match the one on the bottom.

author: MiDi
author_rank: Frequent Contributor
timestamp: December 03, 2018, 09:53:52 am
content: Top gives exact same datecode and number.The marking is not consistent with older order.The cases are flat on both sides, the former ones have bevel on both sides.NewOldLeft side is older order, right side new with different markings.So obvious they are fakes.

author: Andreas
author_rank: Super Contributor
timestamp: December 08, 2018, 09:48:43 am
content: Quote from: GigaJoe on December 03, 2018, 03:38:42 amI fear you are right.I did a acetone test on 2 parts.The black topping easily was removed.On the first view I did not recognize that the parts have been black topped and remarked.with best regardsAndreas

author: iMo
author_rank: Super Contributor
timestamp: December 08, 2018, 10:48:40 am
content: Open a fake package and have a look at the chip die..

author: Andreas
author_rank: Super Contributor
timestamp: December 08, 2018, 11:29:04 am
content: Hello,as there are not much options for a 10V buried zener,I guess most of the parts are re-labeled from JQ to LQ.So you will not see it by the chip itself since the grades are selected by the manufacturer.The ongoing T.C. measurements also indicate JQ devices.Except the 5V part and eventually the noisy 10V part.But it could also be that the noise results from a mis-treatment.with best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: December 08, 2018, 06:11:23 pm
content: seems true. another thing are fully tin coated pins, so chips simply dumped in a liquid tin, for how long ... unknown ...

author: GigaJoe
author_rank: Frequent Contributor
timestamp: April 03, 2019, 04:24:34 am
content: quite redonkelous quaestio:Assuming i will feed AD587 by meander in 10 sec period. Will it help "make it stronger" , or a wasting time?

author: Andreas
author_rank: Super Contributor
timestamp: April 03, 2019, 08:02:14 pm
content: Hello,what exact do you mean with "make it stronger".10 sec period is not enough time to heat up and cool down the AD587.What I did with a AD586 (5V-version of AD587) is moving the ageing faster to its final state (< 2 ppm/year)by loading the output with 15 mA over night with a supply of 14V at the input.(so heating the AD586 with 15 mA * (14V-5V) = 135 mW additionally to self heating periodically).After some weeks the initial ageing of 3.4 ppm/sqrt(kHr)/ new ageing from day 420 with 2.4 ppm/sqrt(khr) suddenly got slower.light blue: initial ageing from day zeropink: ageing from beginning with 15mA load over night (from day 420)with best regardsAndreas

author: GigaJoe
author_rank: Frequent Contributor
timestamp: April 04, 2019, 07:54:35 pm
content: ok ...but the load as a current flow, has no affection on zener, just a heat, as site effect of load, I assume.means: if my chip in a heater, that would be the same effect.... OK .. i get it ... the best way to cycle the heater ...

author: Noopy
author_rank: Super Contributor
timestamp: February 25, 2020, 09:30:54 pm
content: I opened the parts MiDi had ordered:https://richis-lab.de/REF06.htmSurprise: They are all genuine parts:Nice resistor tuning track. It gives a big change at the beginning and a small change at the end of the line.Perhaps that´s the buried zener...Six dies are showing nothing special but on three dies there is dirt!It looks like the cement holding the package together.More Pictures on my website:https://richis-lab.de/REF06.htmI assume all the AD587 are rejected parts. With that in mind you have to fear that "good" AD587 out of this charge are also not really good...

author: magic
author_rank: Super Contributor
timestamp: February 28, 2020, 08:26:52 am
content: For completeness, this was shown in older datasheets:No idea what ground force/sense isMaybe just separate grounds for the precision bits and the buffer opamp. I think it may be this, the "sense" connection seems to go solely to the suspected zeners and some thin film resistor...The output may have actual force/sense connections.

author: magic
author_rank: Super Contributor
timestamp: February 29, 2020, 08:39:11 am
content: I had a second look. Despite two metal layers and low resolution, after some digital enlargement the image is surprisingly readable.The right output pad appears to be "force" and the left "sense". The resistor to the left of output sense is the feedback resistor, the (trimmed) resistor below it at the bottom of the die is the gain resistor. Their junction goes towards those six transistors laid out symmetrically in the center. This looks like a µA741-style input stage, this time fully symmetric and without built-in offset trickery. That's in agreement with the simplified schematic.The test pads below the output pads appear to be connected right across the die to the corresponding output padsThe pads on the left go somewhere into the reference, including the square trimmed resistor, but contrary to the datasheet show no signs of being bonded to the package.

author: Noopy
author_rank: Super Contributor
timestamp: February 29, 2020, 08:48:24 am
content: Quote from: magic on February 29, 2020, 08:39:11 amNeed more resolution?https://richis-lab.de/temp/AD587LQ.JPG

author: magic
author_rank: Super Contributor
timestamp: March 03, 2020, 07:53:07 am
content: A little schematic of the reference section. This is a comparatively simple circuit with no provisions for permanent adjustment other than the laser trim.Some remarks:R1 is trimmed to mirror a controlled fraction of R2 voltage.Q1 base current is cancelled by Q2 and the mirror.Q1 base voltage is subtracted from the output by Q3.Q4 performs similar subtraction and generates constant current in R4. R3 current drops with temperature, increasing Q4 currentQ4 and Q5 are twice the area of Q3 and Q6, R5 is half as long as R6. Not sure what's the point. Not sure what R7 is doing.Q10 and the rest hopefully play no role other than starting up the circuit.tp1, tp2 and tp3 are the test pads. I don't count tp0, which is just a dummy resistor. They could be exploited for external TC nulling, but don't seem to be connected.

author: miklos2
author_rank: Newbie
timestamp: May 10, 2021, 04:09:21 am
content: Lars wrote <https://www.eevblog.com/forum/metrology/best-out-of-the-box-10v-reference/100/"Joe used the LQ and I think all had the date code 0045. Most of the LQ Joe had were around +2ppm/C at 25C so the simple add-on with a NTC+ resistor worked well."I purchased three of the legendary AD587LQ with date code 0045 from Canada, Mississauga in 2021 april. Component Electronics, stock# AD587LQ-AD1.They seems new, nothing suspicious. I made fast temperature sweep test with next results:AD587LQ (1) at 25°C 10V+2,01mV; ∆U(20°C-40°C) 14ppm; histeresis<1ppmAD587LQ (2) at 25°C 10V+2,01mV; ∆U(20°C-40°C) 18ppm; histeresis 2ppm (32°C-38°C), 1ppm <32°CAD587LQ (3) at 25°C 10V+1,63mV; ∆U(20°C-40°C) 8ppm; histeresis 1ppm (34°C-38°C), <1ppm <34°CThe test started at 40°C, then cooling to 20°C (15 minutes) and heating to 40°C (15 minutes).Devices: a piece of copper and Peltier element. Voltage measurements with Keithley DMM6500 (1 measure/sec), temperature measurements with another synchronized voltmeter (hp3455A) and LM335 fixed on the copper.

author: miklos2
author_rank: Newbie
timestamp: May 10, 2021, 07:28:16 am
content: The histeresis of the three AD587LQ date code 0045. Signed with arrow the cooling side of diagram.

author: eplpwr
author_rank: Regular Contributor
timestamp: May 10, 2021, 07:51:55 am
content: I have some chips marked "AD587LQ/+", they measure according to spec. Does anyone know what the /+ suffix means?

author: Andreas
author_rank: Super Contributor
timestamp: May 10, 2021, 05:35:41 pm
content: Quote from: miklos2 on May 10, 2021, 04:09:21 amHello,with a 15 minute ramp: are you shure that the "hysteresis" is real.Or is it only the temperature difference between temperature sensor and AD587 internal chip temperature?with best regardsAndreas

author: Terry Bites
author_rank: Super Contributor
timestamp: May 10, 2021, 06:18:35 pm
content: octo say there is stockhttps://octopart.com/ad587lq-analog+devices-522211

author: miklos2
author_rank: Newbie
timestamp: May 11, 2021, 07:21:15 am
content: "with a 15 minute ramp: are you shure that the "hysteresis" is real."Hello Andreas!I'm not sure, but I made the measurements with another three AD587LN and the hysteresis was not consistent. The plastic AD587LN I bought on ebay 5USD/pc. They are used but not soldered, I think, worked on socket. Individual mark on the bottom K3, B8, X9, date code 9947, 9947, 9746.During the temperature sweep measurements I controlled Peltier voltage by hand so I have to learn nice sweep with AD589LQ (3) (60 minutes) and AD587LN (K3) (52 minutes). The CERDIP and plastic PDIP package have different thermal resistance so it would be the same hysteresis the 3 CERDIP and other but same hysteresis the 3 PDIP, and the branches of the diagram would be parallel the full temperature range ( like AD587LN (B8)).The devices and the arrangement was the same all the 6 AD587 measurements, but the hysteresis was not consistent so there was no measuring error, the hysteresis real.I attached the voltage-time diagrams of AD587LN-s and LQ-s on the output (LQ1 was not saved).

author: Kleinstein
author_rank: Super Contributor
timestamp: May 11, 2021, 09:07:40 am
content: The curves come back quite well when back to room temperature. So it does not look liks hysteresis, more like some delayed effect, maybe just the internal temperature different from the thermometer. Different cases can have a different delay and heating controlled by hand may mean a not so constant / repeatable speed.Hysteresis is normally also more expected for larger excursions, like going up to 100 C or so and than back to RT.