Author Topic: Data on various voltage reference ICs over time.  (Read 693 times)

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Offline Insatman

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Data on various voltage reference ICs over time.
« on: November 27, 2017, 06:07:40 PM »
Greetings,  Over the past several months I have been testing a variety of voltage reference ICs.  4.096V, 5V and 10V references ICs are tested from a variety of manufactures.  All ICs were purchased new from Digikey.  Temperature/Humidity data is overlayed where available.  Note; you can use the humidity data for all three charts but only the 10V data has it overlayed.   All measurements are made using an HP34401A.  The unit isn't in official cal, but has been checked against a calibrated reference from VoltageStandards.com and is well within spec. 

Enjoy
Insatman
Retired Pulsed Power Engineer/Physicist...now I just dabble in electronics
 
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Offline Andreas

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Re: Data on various voltage reference ICs over time.
« Reply #1 on: November 27, 2017, 06:44:42 PM »
Hello,

Interesting work.

some questions arise:

- how is the setup made? Devices soldered directly on board or socketed or dead bug style mounted?

- VRE305 returned to APEX (why?)
With 2 samples of VRE3050A I had the experience that they have large noise and large hysteresis (T.C. was within or near spec)

- do you know the T.C. of your DMM?

- do you have the values as .CSV or .TXT
  the different scales makes it difficult for me to see details on the more stable devices.

with best regards

Andreas


 

Offline Insatman

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Re: Data on various voltage reference ICs over time.
« Reply #2 on: November 28, 2017, 08:05:28 PM »
@Andreas,
I will try and answer your questions.
 
The setup used.  Most devices are socketed in the fixture pictured in the attachment.   I built this fixture to test and age devices for use later in various projects, so I used sockets.  Note the VRE305 socket is a high quality mil-max socket, the others are standard 8 pin sockets from digikey. 

A few devices are in various reference boxes such as the one marked on the 10V chart as "PTC AD587UQ"  This device is thermally stabilized with a PTC thermistor as an experiment.
 
A list of the devices not in the fixture follows.
10V REF01EP-1 is socketed and housed in a project box.
10V PTC AS587UQ is socketed and thermally stabilized using a PTC thermistor.
10V AD587UQ-1-HP is socketed and housed in a aluminum "hotbox" which is maintained at 52C via a PWM heater servo.
10V MV-106...this is my EDC voltage standard and really doesn't belong on this chart but appears for reference
10V LM399 is soldered into a voltage reference circuit in a project box.
5V LT1460GCZ5-1 is soldered and housed in a project box (same box as REF01EP-1)  I suspect that some of the noise on the other LT1460 devices is from the sockets used.


VRE305.  I returned the first VRE305 because it was clearly out of spec for initial voltage output and it looked like it was also drifting much more than spec.  After submitting my data to APEX they agreed to ship me a new one if I returned the old one.   We each paid for shipping...me to return and APEX to send me a new one (FedEx no less).   The new unit is working much better than the original.  A friend of mine who has extensive experience with the VRE305 says that the units made by APEX are not so good anymore.  The original units (can't remember original manufacturer) were much better.   These chips are pricey...more than LTZ1000.  I don't recommend them.

My DMM is an HP34401A which for this voltage and range setting is specified at 6uV/degC maximum.  I suspect the real value is somewhat lower than that.

The data is in an Excel file which can be exported to CSV ore TXT.   PM me and I'll send you whatever format you perfer via private email. 

Insatman

Retired Pulsed Power Engineer/Physicist...now I just dabble in electronics
 
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Online beanflying

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Re: Data on various voltage reference ICs over time.
« Reply #3 on: November 29, 2017, 09:23:46 AM »
Interesting information.

On the 5V data any idea what happened to the measured data between about 7-800 hours? There seems to have been some strange positive and negative drifts happening?

Coffee, Food, R/C and electronics nerd in no particular order :)
 

Offline Insatman

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Re: Data on various voltage reference ICs over time.
« Reply #4 on: November 29, 2017, 06:12:02 PM »
@beanflying,

i'm not sure actually.  Early on I didn't have automatic temp/humidity logging.  So I don't know if that was a factor.   

Insatman.


Interesting information.

On the 5V data any idea what happened to the measured data between about 7-800 hours? There seems to have been some strange positive and negative drifts happening?
Retired Pulsed Power Engineer/Physicist...now I just dabble in electronics
 

Offline Andreas

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Re: Data on various voltage reference ICs over time.
« Reply #5 on: December 01, 2017, 01:04:02 AM »
Hello Insatman,

thanks for the offer. But I fear that the devices of interest will have near equal T.C. to a 34401A if you do not have narrowed down the data sheet value by a measurement.

With best regards

Andreas
 

Offline Insatman

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Re: Data on various voltage reference ICs over time.
« Reply #6 on: December 01, 2017, 01:44:05 PM »
@ Andreas,
I see your point.  At present I lack a method of doing that measurement with sufficient accuracy.   One of the motivations for building/testing various references was to have a stable enough source for such a measurement.  At that point I would have to build some sort of environmental chamber for the device under test (34401A).   I'm not at that point however.   What is useful is looking at the group in total and see which are most stable and of those stable ones to look for patterns of like movement which could infer the meters tempco.  Especially if the sources moving together are unlike devices.   

I've also acquired additional 6.5 digit meters and am comparing them to one another over time.  This may also at least let me bracket the tempco/drift.  At present a 7.5 or 8.5 meter is just too expensive for me, unless a real bargain pops up.   

Insatman

Hello Insatman,

thanks for the offer. But I fear that the devices of interest will have near equal T.C. to a 34401A if you do not have narrowed down the data sheet value by a measurement.

With best regards

Andreas
Retired Pulsed Power Engineer/Physicist...now I just dabble in electronics
 


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