Author Topic: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x  (Read 237865 times)

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Offline zlymexTopic starter

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #200 on: November 20, 2016, 01:40:44 pm »
So there are "multiple" different datasheets spreading in the wild ?  :palm:
There are, but not contradictory, only one has slightly more information than the other.
The datasheet I was referred to(with pin dots explaination) is on the very first page of this thread.
 

Online Gyro

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #201 on: November 20, 2016, 03:40:34 pm »
Unfortunately (for most of us anyway) it's in Chinese. The only English language data we have is what technix kindly translated (and even that doesn't include information on the dot significance).
« Last Edit: November 20, 2016, 03:42:30 pm by Gyro »
Best Regards, Chris
 

Offline technix

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #202 on: November 20, 2016, 08:30:42 pm »
Unfortunately (for most of us anyway) it's in Chinese. The only English language data we have is what technix kindly translated (and even that doesn't include information on the dot significance).
I have contacted the factory about the dot last Friday, and at least for Shanghai No. 17 Radio Factory their dots don't signify anything regarding pins.

The one I translated is extracted from the catalog the factory provided me.
 

Offline edavid

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #203 on: November 20, 2016, 08:34:27 pm »
I have contacted the factory about the dot last Friday, and at least for Shanghai No. 17 Radio Factory their dots don't signify anything regarding pins.

The one I translated is extracted from the catalog the factory provided me.

Did you ask them about why the datasheet has the wrong pinout?
 

Offline technix

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #204 on: November 20, 2016, 08:39:56 pm »
I have contacted the factory about the dot last Friday, and at least for Shanghai No. 17 Radio Factory their dots don't signify anything regarding pins.

The one I translated is extracted from the catalog the factory provided me.

Did you ask them about why the datasheet has the wrong pinout?
The one on the first page is not their datasheet.
 

Offline edavid

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #205 on: November 20, 2016, 11:21:55 pm »
I have contacted the factory about the dot last Friday, and at least for Shanghai No. 17 Radio Factory their dots don't signify anything regarding pins.

The one I translated is extracted from the catalog the factory provided me.

Did you ask them about why the datasheet has the wrong pinout?
The one on the first page is not their datasheet.
Your translation has the wrong pinout also - did that come from their datasheet?
 

Offline technix

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #206 on: November 21, 2016, 06:51:27 am »
I have contacted the factory about the dot last Friday, and at least for Shanghai No. 17 Radio Factory their dots don't signify anything regarding pins.

The one I translated is extracted from the catalog the factory provided me.

Did you ask them about why the datasheet has the wrong pinout?
The one on the first page is not their datasheet.
Your translation has the wrong pinout also - did that come from their datasheet?
No that one is not. I measured it and put the words in a wrong way. I will fix it and reupload.
 

Offline Alex Nikitin

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #207 on: November 21, 2016, 12:30:35 pm »
Hmm, by far the most stable results I get are from a single zener (without the second diode in series), at about 1.4mA current and 5.246V zener voltage (the same setup as before, the resistor value is 3430 Ohm). Here is a 10min run, vertical scale 0.1ppm (0.5uV), HP3458A at NPLC100.

Cheers

Alex
« Last Edit: November 21, 2016, 12:36:51 pm by Alex Nikitin »
 
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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #208 on: November 21, 2016, 01:14:54 pm »
My opinion is that at room temperature, the shape of the TC curve is "peaky". There may be an optimal current at room temp, but if room temp wanders even a little bit, the voltage is much too sensitive.

If the shape of the datasheet TC curve can be believed, it appears that these 2DW23X parts behave much better at 50 deg C than at room temperature.

To prove this will require some gear that at present I do not possess.

Here is what I did to satisfy my curiosity, I ran one of the 2DW parts in a banana jack mounted to the front of a KE2461. I manually searched for a current that gave as stable of a voltage as possible. The I touched the metal can. Immediately the voltage started to climb.

Another thing that may help is to create a solid copper heatsink into which the 2Dw package can be inserted.
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Offline Alex Nikitin

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #209 on: November 21, 2016, 02:07:25 pm »
Here is what I did to satisfy my curiosity, I ran one of the 2DW parts in a banana jack mounted to the front of a KE2461. I manually searched for a current that gave as stable of a voltage as possible. The I touched the metal can. Immediately the voltage started to climb.

This way you are finding a thermal balance, not a zero tempco. Try the current value about 1.4mA I've found for a single zener (the second half is not connected).

Cheers

Alex
 

Offline TiN

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #210 on: November 21, 2016, 02:26:35 pm »
I can test up to 65-70C for theories above ;)
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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #211 on: November 21, 2016, 03:31:00 pm »
I can test up to 65-70C for theories above ;)

...and you write Ninja Python code. You can create an automatic characterization program and save a mountain of data.
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Online Gyro

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #212 on: November 21, 2016, 03:58:38 pm »
You might want to try going to a much higher current in the series zener+diode mode. One of my samples is shifting by around 10uV when subjected to the cold finger test while running at 20mA.  That's very roughly the same order of shift as I see in my 1N829A at it's nominal zero Tc current (8mA).
Best Regards, Chris
 

Offline technix

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #213 on: November 21, 2016, 04:13:26 pm »
I can test up to 65-70C for theories above ;)

...and you write Ninja Python code. You can create an automatic characterization program and save a mountain of data.
Maybe I will try the automated characterization process if I know hoe to get good measurement, and give you guys an updated translated datasheet with some measured data points.
 

Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #214 on: November 21, 2016, 04:22:03 pm »
You might want to try going to a much higher current in the series zener+diode mode. One of my samples is shifting by around 10uV when subjected to the cold finger test while running at 20mA.  That's very roughly the same order of shift as I see in my 1N829A at it's nominal zero Tc current (8mA).

Did you wrap the device to reduce air flow over the device?
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Offline Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #215 on: November 21, 2016, 04:32:24 pm »
Hmm, by far the most stable results I get are from a single zener (without the second diode in series), at about 1.4mA current and 5.246V zener voltage (the same setup as before, the resistor value is 3430 Ohm). Here is a 10min run, vertical scale 0.1ppm (0.5uV), HP3458A at NPLC100.

This is very interesting. So it looks like one can also use it as a 5.2-5.3 V reference at lower current. For some applications this can be the more interesting operating point, as it is lower power and a divider from 5.3 V to 5 V (or 10.5 V to 10 V) is less sensitive to resistor drift as one from 6 or 7 V. Reducing the sensitivity of the resistors by something like a factor of 5 can be a really big advantage.

Even with this lower power, it looks really low noise and stable. For most application this can be good enough - hard to find something with lower noise. You have to take into account that some of the noise in the curve could be still the LTZ1000 inside the 3458.

The curve shape with a maximum in voltage over temperature will likely exist at all currents. Changing the current will shift the maximum and thus the temperature with zero linear TC to different temperatures. So there is likely nothing special with the 50-60C temperature where the curve in the DS has its maximum. Finding the compensating current is finding the curve where the maximum (and thus zero slope) is at the working temperature.

Choosing a higher, regulated temperature (which might end up at 50 C because this a practical temperature) is attractive as in the horizontal region of the curve there is no need for a super stable temperature.

 

Online Gyro

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #216 on: November 21, 2016, 06:51:56 pm »
You might want to try going to a much higher current in the series zener+diode mode. One of my samples is shifting by around 10uV when subjected to the cold finger test while running at 20mA.  That's very roughly the same order of shift as I see in my 1N829A at it's nominal zero Tc current (8mA).

Did you wrap the device to reduce air flow over the device?

Sorry, got called away. That was free-air, I wasn't looking for precise results, just trying to find a turnover point. I was driving it in Zener+diode mode (dot pin -ve), via a 1k resistor. Applying a cold finger was causing an increase in voltage up to about 26V input, above 27V input it turned over and started dropping instead. At about 26.5V it seemed to reach equibrium (~10uV shift). At all times the device felt warm / hot so I was always applying a cooling effect.

Not a particularly scientific test I know, but I was getting fed up with seeing large (100uV or more) shifts when I touched the package and decided to just keep ramping up the current to see what happened. 20mA was way above the current I was expecting to apply. I haven't yet tried the same on other devices to see how repeatable this is - this current is uncomfortably close to the 30mA Iz Max.

Edit: Maybe this is the current level needed to hit 50'C package temperature in free-air, so you could maybe achieve the same result at lower current if package is thermally insulated.
« Last Edit: November 21, 2016, 06:55:29 pm by Gyro »
Best Regards, Chris
 

Offline BravoV

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #217 on: November 21, 2016, 07:18:53 pm »
Maybe I will try the automated characterization process if I know hoe to get good measurement, and give you guys an updated translated datasheet with some measured data points.

Please delete the 1st translated datasheet, as it may mislead future readers.

And post the original datasheet here that you got from the manufacturer, even its in Chinese, at least Zlymex can verify your translation.

Offline technix

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #218 on: November 21, 2016, 07:53:03 pm »
Maybe I will try the automated characterization process if I know hoe to get good measurement, and give you guys an updated translated datasheet with some measured data points.

Please delete the 1st translated datasheet, as it may mislead future readers.

And post the original datasheet here that you got from the manufacturer, even its in Chinese, at least Zlymex can verify your translation.
I will delete the original translation if you find it misleading. Keep in mind that this is the very first sentence an instructor will tell every Chinese EE student: do not trust in datasheets blindly, characterize everything yourself before using it.

Those parts made under Chinese traditional part numbering systems can (when talking parts made before the mid-80s the word would be "very likely will") vary from piece to piece as the standards is extremely lax. So if you are using parts in Chinese part numbering system, measure it before even thinking about using it, as you may be in for a surprise, especially when talking about older parts.

The discrepency between the datasheet Zlymex posted and the pinout the factory told me (not in the original datasheet - I had to phone in to confirm) is a clear indication of this problem.
 

Offline Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #219 on: November 21, 2016, 08:14:37 pm »
Using the finger to test the sensitivity to temperature can be a little misleading: there are two point where the finger will not cause a change: one is when the TC of the device is zero and a second is when the device temperature is the same as the finger, so there will be no more change in temperature.
 
Increasing the current will also increase the temperature, so one is probing at different temperatures, not just different currents. It depends on the thermal design how those two parameters are combined.

From the turn on transients the VintageNut did, the TC seems to turn more negative at higher current. It is still the question if this due to the higher temperature or due to the higher current. The test is still useful to find the suitable current for the given thermal conditions. However one tends to look at the changes below (before) equilibrium temperature. So it is not the most accurate way.
Form the curved shape of the curve in the DS it is suggested that a higher temperature gives a more negative TC. If the DS curve can be believed this would be something like -0.2 ppm/K². So a self heating of 10 K would change the TC by about -2 ppm/K.

Without a good DS, the logical thing would be to measure the curves you would wish to have in a good DS.
To get data relative to the true chip temperature one could use the normal diode as an approximate temperature sensor. This would need 2 voltmeters and likely an external heater. The DMM for the normal diode voltage (-> temperature) does not need to be that accurate, but the one for the zener voltage should be. So it would be first to check the forward diode with current only through that diode (to reduce self heating), or maybe use the start of transient. Than with the same current one could test on increasing temperature. So raw data would be zener voltage versus diode voltage.

The measurements from Alex Nikitin suggest, the using only one diode (and lower current) might be the even more interesting operation point.
 
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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #220 on: November 22, 2016, 02:11:58 am »
I drilled a hole in a solid copper plate and placed a 2DW232 inside the hole and mounted that on the front of the KE2461. Using 3mA, after a long stabilization period, the short term standard deviation is 2uV. That looks promising.

I still think that running this device close to 50C will give the best long term stability.

I am looking forward to someone having a proposed method of ovenizing this device. 
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Offline Galaxyrise

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #221 on: November 22, 2016, 03:28:35 am »
Thank you Zlymex and VintageNut for letting me play in these reindeer games :)

I've been working on a little temperature controlled test environment and put it to work this weekend running tests on one of the ones
I got, hunting for an inflection point in the temperature response. I ran it at various currents from 3mA to 18mA, changing the temperature of the chamber from 23C to 40C.  Consistent with the findings of others in this thread, the TC did not change sign in this interval, with the smallest tempco being at 18mA.  (I observed roughly 25ppm/C at 18mA. Even though the test wasn't set up to accurately measure TC, it still seemed like a pretty linear temperature response from 23 to 35C at that current.) 

I don't know what the die temperatures were, since I haven't done a pulsed current test yet.  (I need a different setup to take measurements fast enough.)

I just got some enameled nichrome wire, so I'm going to try to turn one of things into a little oven and see if I can find the temperature response curve from the datasheet.  Then I can use the zener voltage at that zero point to stabilize it.
I am but an egg
 
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Offline Galaxyrise

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #222 on: November 22, 2016, 07:30:04 am »
I got things set up and did a fairly extreme temperature excursion at 5mA (I raised the outside to about 113C, though the die temperature was certainly much lower.)  The zener voltage followed a curve not unlike the datasheet.  However, the zener's parabola was only just barely visible in the total voltage; the magnitudes of the temperature coefficients is that different at 5mA.

Last thing I did before bed was to bump the current up to 10mA.  I did not have the time to do this one properly, but I did not see an inflection point in the zener voltage any more (dV stayed positive for the entire test), and the overall TC looked much less.

I am but an egg
 

Offline Alex Nikitin

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #223 on: November 22, 2016, 11:47:01 am »
Here are the overnight results with a single zener and 1.38mA current. The tempco is about -6ppm/C, the noise is low and the stability looks good. 2ppm/div vertical scale on Volts.

Cheers

Alex
« Last Edit: November 22, 2016, 11:55:06 am by Alex Nikitin »
 
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Offline VintageNut

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #224 on: November 22, 2016, 12:06:50 pm »
This is good information. Here is what I see. For most of this time span, the voltage is rising despite what is happening with temperature. At around 08:00, the voltage is stable. After stability is reached, the zener voltage responds to temperature change in the opposite direction of the temperature change.

This long time to warm up is what I have seen operating the device in its intended configuration. If the device is operated at a temperature much higher than ambient, then the warmup time should be eliminated.



Here are the overnight results with a single zener and 1.38mA current. The tempco is about -6ppm/C, the noise is low and the stability looks good. 2ppm/div vertical scale on Volts.

Cheers

Alex
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 


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