Author Topic: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x  (Read 175656 times)

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Offline KK6IL

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #625 on: October 17, 2020, 04:58:18 am »

I ordered 20 from the address MegaVolt supplied, and received 2 packages of 20 each, date code 15-4 (and 2 credit card charges). I may or may not have double ordered, not being used to AliExpress. Inked markings not very distinct.

With Pipelie's warning, I wanted a quick noise test so set up a comparison with a LM329. I set up a test using my LM399 standard as the source, 3K resistor for the LM329, and 750 ohms for the 2DW323, pins 1 & 2. Measured with Tek 7A22 plug-in set to 1Hz-1kHz bandwidth. Photos captured with Hantek DSO connected to 7834 Vertical Output. LM322 voltage source measures 35.6uV P-P. LM329 measures 25.2uV P-P, and 2DW232 measures 5.2uV P-P.

 
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Offline Andreas

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #626 on: October 17, 2020, 02:15:46 pm »
Hello,

so you have 1:50000 amplification?

Hmm, to measure 1Hz you would need a minimum sweep time of 1 second.
Otherwise you get another pole by the limited measurement duration.

with best regards

Andreas
 
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Offline KK6IL

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #627 on: October 17, 2020, 11:43:39 pm »
You're correct. The high pass filter on the 7A22 plug-in ( love those) was set to 1 Hz, but the sweep time would have to be set slow to actually show really low freq noise.

I was just glad to see that the 2DW232's from that site were real Diamond components and were low noise compared to the LM329's.

I built a copy of a "low noise" 60 db amp, and was trying to add that to the test setup to get further above the scope noise when my LM399 supply started latching into a 3.5V output mode,  |O so will need to build a low noise, higher current supply to do further testing. The DW will be good for that as I will only worry about short term stability, and not 0 TC.
 

Online Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #628 on: October 18, 2020, 09:28:31 am »
Chances are that even the not so good 2DW232 would be OK at the higher frequency. The real test is for the low frequency range and 1/f noise. The 1/f noise is what depends one purity and can vary between batches.

For a simple noise test one would ideally have to independent references and than measure the difference.
There is no real need to have a separate low noise supply. The normal 1 OP amplification of the ref. and getting the current from the amplified voltage should be Ok. This may even work with an LM358 on a breadboard - though poor contacts can be a hassle.
The difficulty may be more in setting the right current as 1/f noise and temperature fluctuations can look similar.
 

Offline edavid

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #629 on: October 19, 2020, 03:46:51 pm »
be ware that not all the 2DW232 with diamond mark is the low noise one. we have tested samples from several source and we found the date code start with 12-xx and 13-xx are most likely the low noise one. the newer one is probably not, such as the 14-xx to 15-xx we tested are kind of bad.

Pipelie, what is your noise test method?
 

Offline Pipelie

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #630 on: October 20, 2020, 06:58:58 am »
Hi edavid,

the LNA I'm using is this one. https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/50/
also check post #195 for user manual. https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/175/

test method:
[attachimg=1]

result of 2DW234:
[attachimg=2]

and others


 
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Online serg-el

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #631 on: January 30, 2021, 09:26:47 pm »
Something no one writes for a long time.
I will add my measurements 2DW232.
Purchased 30 pieces for aliexpress.
The logo and date are present.



The legs are entirely made of kovar.
They are attracted by the magnet quite strongly.

Measurements were performed by R6871E and TR6142.
Temperature sensors LM35.
Self-heating readings were taken after stabilization for 30 minutes.
2DW232 is wrapped in polyester quilt wadding and placed in a jar.
The jar is closed with a lid and crushed by a load.

The time of 30 minutes was chosen for a reason, but after the current was set and the temperature stabilized.
I got a stabilization time constant of ~ 25 minutes.
Despite the fact that according to the documentation, the operating current is not more than 30 mA, 2DW232 survived,
  and did not change my reading after I applied a current of 110 mA to it.
The characteristics of the dependence of the voltage and temperature of self-heating on the current are taken.

To find the zero temperature coefficient point, a macro was compiled in EZGPIB.
Turn off the current - hold 10 seconds for a little cooling - set the current - turn on the current - hold 3 seconds - 50 voltage and temperature measurements - repeat.
In my case, it turned out 11.4 mA.


The dynamic resistance is calculated based on the set current and the measured voltage.


If you need data in CSV format, I'll be happy to provide.
Any suggestions and comments are welcome.

Macro EZGPIB
Code: [Select]
Program V_I_Logger;                 // Программа для снятия ВАХ

const MakeModel_DVM='R6871E';             // Указать модель мультиметра
const MakeModel_PS='TR6142';              // Указать модель источника питания
const GPIB_address_DVM = 1;              // Указать адрес мультиметра на шине GPIB
const GPIB_address_PS = 4;               // Указать адрес источника питания на шине GPIB

const Directory = 'C:\Incoming';     // Путь для сохранения файла CSV
const Timeout = 5;
//const Descript = 'тест тока TR6142 ';     // Описание измерений
const Descript = '2DW232 1+ и 2- вывод CI5 IT6 11...13 mA';     // Описание измерений

var Filename : String;
var t_start_datetime: TDateTime;           
var t_acq_datetime: TDateTime;             
var tmp_str:String;
var elapsed_time:longint;
var Answer:String;
var Ivdc_set:String;

var Temp_in:String;
var Temp_out:String;
var Count:integer;
var Count_str:String;
var Count_single:single;
var Count2:integer;
var Make:String;
var Maker:TDateTime;
var i:integer;
var Answer_dbl:Double;

procedure Init_File;
begin;
   Maker := EZGPIB_TimeNow;                          // Дата/время создания файла
   EZGPIB_FileClearBuffer;
   tmp_str:='date';                                  // First column
   EZGPIB_ConvertAddToString(tmp_str,';');
   EZGPIB_ConvertAddToString(tmp_str,'VDC' + ';' );
   EZGPIB_ConvertAddToString(tmp_str,'Idc' + ';' );
   EZGPIB_ConvertAddToString(tmp_str,'Temp_in °C'+';');         
   EZGPIB_ConvertAddToString(tmp_str,'Temp_out °C'+ #13 + #10);     //  + пустую строку для более простого выделения столбца в Excel
   EZGPIB_FileAddToBuffer(tmp_str);                 
   Filename := Directory +'\';
   EZGPIB_ConvertAddToString(Make,Maker);
   Make := AnsiReplaceText ( Make, ':', '_');        //Замена недопустимых символов в имени файла
   EZGPIB_ConvertAddToString(Filename,Make);
   EZGPIB_ConvertAddToString(Filename,' '+ MakeModel_DVM);
   EZGPIB_ConvertAddToString(Filename,'.csv');       
   EZGPIB_FileWrite(Filename);                       // Save File
end;

procedure Save_Descript;
begin;
   EZGPIB_FileClearBuffer;
   tmp_str :='';
   EZGPIB_ConvertAddToString(tmp_str,Descript +#13+#10);     // Описание измерений
   EZGPIB_FileAddToBuffer(tmp_str);                   // Add to file buffer
   EZGPIB_FileWrite(Filename);                        // Save File
   EZGPIB_ScreenWriteLn(tmp_str);
end;   

procedure Save_File;
begin;
   EZGPIB_FileClearBuffer;
   tmp_str :='';   
   EZGPIB_ConvertAddToString(tmp_str,t_acq_datetime); // First column 
   EZGPIB_ConvertAddToString(tmp_str,';');             
   EZGPIB_ConvertAddToString(tmp_str,Answer);         // Second column
   EZGPIB_ConvertAddToString(tmp_str,';');   
   EZGPIB_ConvertAddToString(tmp_str,Ivdc_set);
   EZGPIB_ConvertAddToString(tmp_str,';');   
   EZGPIB_ConvertAddToString(tmp_str,Temp_in);
   EZGPIB_ConvertAddToString(tmp_str,';');   
   EZGPIB_ConvertAddToString(tmp_str,Temp_out); 
   EZGPIB_FileAddToBuffer(tmp_str);                   // Add to file buffer
   EZGPIB_FileWrite(Filename);                        // Save File
   EZGPIB_ScreenWriteLn(tmp_str);
   tmp_str :='';   
end; 

procedure Init_Device_DVM;
begin;
   EZGPIB_BusAutoOff; // Эквивалент команды ++auto 0
   EZGPIB_BusWriteData(GPIB_address_DVM,'Z');            // Reset to defaults
   EZGPIB_TimeSleep(5);
   EZGPIB_BusWriteData(GPIB_address_DVM,'ac');           // Acal execute
   EZGPIB_TimeSleep(3);
   EZGPIB_BusWriteData(GPIB_address_DVM,'++read_tmo_ms 5000'); // установка таймаута 10 сек
   EZGPIB_BusIFC; // Perform an Interface Clear
   EZGPIB_BusEnableEoi;
   EZGPIB_BusSetEos(0);           
   EZGPIB_TimeSleep(1);
   
    // IT8 100 PLC
    // IT7 50 PLC
    // IT6 20 PLC
    // IT5 10 PLC
    // IT4 5 PLC
    // IT3 1 PLC
    // IT2 10 msec
    // IT1 1 msec
    // IT0 100 usec
   
    //CI acal interval, min
   
    //F1  --> VDC
    //F2  --> VAC
    //F3  --> 2W Ohm
    //F4  --> 4W Ohm
    //F5  --> ADC
    //F8  --> VDC + ADC
    //F9  --> ADC + AAC
   
    //R5  --> 20 V
    //R6  --> 200 V   
   
   
    //R5  --> 20 mA
    //R6  --> 200 mA
   

   EZGPIB_BusWriteData(GPIB_address_DVM,'F1,R5,M1,IT6,SI0,TD0,AZ1,RE7,CI5');
   EZGPIB_TimeSleep(2);
   EZGPIB_BusWriteData(GPIB_address_DVM,'H0,S0,SL2,DL0,CS');
   EZGPIB_TimeSleep(5);
   EZGPIB_BusAutoOn;   
end;
procedure Init_Device_PS;
begin;
   EZGPIB_BusAutoOff;
   EZGPIB_BusWriteData(GPIB_address_PS,'C');
   EZGPIB_TimeSleep(1);
   EZGPIB_BusWriteData(GPIB_address_PS,'I3');

end;
// Main procedure 
begin;
   EZGPIB_screenclear;                      // Clear the Output Console
   EZGPIB_BusEnableEoi;
   EZGPIB_BusSetEos (0);
   Init_Device_DVM;                             // Send command strings to meter
   Init_Device_PS;
   Init_File;                             //
   Save_Descript;
   
   //EZGPIB_BusWriteData(GPIB_address_PS,'D.5');  //если надо задать начальный ток
   EZGPIB_BusWriteData(GPIB_address_PS,'E');
      EZGPIB_TimeSleep(0.5);
   
   t_start_datetime :=EZGPIB_TimeNow;     // Get time at beginning of each cycle
   elapsed_time:=0; 
   tmp_str :='';

   while (Count <= 130) and (not ezgpib_kbdKeyPressed) do begin;
    for Count:=110 to 130 do
  begin
     EZGPIB_BusAutoOff;
     EZGPIB_BusWriteData(GPIB_address_PS,'H');     //выдержка времени для короткого остывания 2DW232
             EZGPIB_TimeSleep(10);                          //   -//-
             EZGPIB_BusWriteData(GPIB_address_PS,'E');       // включение выхода TR6142
             EZGPIB_TimeSleep(0.5);
   
           Count_str := IntToStr (Count);     
   Count_single := EZGPIB_ConvertToFloatNumber(Count_str);
   Count_single := Count_single /10 ;
   Count_str := EZGPIB_ConvertToFixed(Count_single,1);  // ;
   Ivdc_set := Count_str;
   

           EZGPIB_BusWriteData(GPIB_address_PS,'D'+Count_str);
           EZGPIB_TimeWaitForMultipleOf(3);      //Выдержка между циклами после установки тока
       
    for Count2:=1 to 50 do
   begin
   EZGPIB_BusAddressDevice (1);

     repeat
       if ezgpib_kbdKeyPressed then exit ;
       EZGPIB_BusAutoOff;
       Answer:='';                             // Clear previous reading
       EZGPIB_BusWriteData(GPIB_address_DVM,'E');
       EZGPIB_BusWriteData(GPIB_address_DVM,'++read');
     i:=0;
       repeat
        EZGPIB_TimeSleep(0.0001);                             
        i:=i+1;
       until (EZGPIB_BusDataAvailable or (i>200000));     
      Answer:=EZGPIB_BusGetData;
     until Length(Answer)>1;     
          Answer_dbl:=EZGPIB_ConverttoFloatNumber(Answer);  //конвертирование ответа из str в экспоненциальный
          Answer:=EZGPIB_ConvertStripToNumber(Answer_dbl);  //конвертирование ответа из exp в числовой
          Answer := AnsiReplaceText ( Answer, '.', ',');   // переделка ответа под стандарт с цифровым разделителем запятой


    EZGPIB_BusAutoOn;   
     repeat   
      Temp_in:='';                             // Clear previous reading
     EZGPIB_BusWriteData(GPIB_address_DVM,'++temp1');
    // EZGPIB_TimeSleep(0.5);
   //  EZGPIB_BusWriteData(GPIB_address_DVM,'++read');
     i:=0;
       repeat
        EZGPIB_TimeSleep(0.001);                             
        i:=i+1;
       until (EZGPIB_BusDataAvailable or (i>2000));     
      Temp_in:=EZGPIB_BusGetData;
     until Length(Temp_in)>1;

       
     Temp_in := AnsiReplaceText ( Temp_in, '.', ','); // переделка ответа под стандарт с цифровым разделителем запятой

     repeat
     Temp_out:='';                             // Clear previous reading
     EZGPIB_BusWriteData(GPIB_address_DVM ,'++temp3');
     //EZGPIB_TimeSleep(0.5);
    // EZGPIB_BusWriteData(GPIB_address_DVM,'++read');
     i:=0;
       repeat
        EZGPIB_TimeSleep(0.001);                             
        i:=i+1;
       until (EZGPIB_BusDataAvailable or (i>2000));     
      Temp_out:=EZGPIB_BusGetData;
     until Length(Temp_out)>1;
     Temp_out := AnsiReplaceText ( Temp_out, '.', ','); // переделка ответа под стандарт с цифровым разделителем запятой           
         
t_acq_datetime := EZGPIB_TimeNow;
        Save_File;                                     // If result contains data, write data to the file
       
       
   end;
end;
   end;
   EZGPIB_BusAutoOff;
   EZGPIB_BusWriteData(GPIB_address_PS,'H');    // выключать выход TR6142 после измерений
end.                                             


edit: Correction of the description of the macro.
« Last Edit: January 31, 2021, 12:40:06 pm by serg-el »
 

Online serg-el

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #632 on: February 04, 2021, 07:57:41 am »
After preheating with a current of 11.4 mA for an hour.
The measurement is more accurate.
The macro is the same.



The noises are low.
No telegraph noise visible.


« Last Edit: February 04, 2021, 12:01:54 pm by serg-el »
 

Online Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #633 on: February 04, 2021, 08:57:39 am »
With only some 12 mA the current is still moderate. In the earier reports the current to reach zero TC showed quite some scattering, possibly to high for practical use. The 12 mA are already higher than the nominal 7.5 mA, and the power loss makes it a little tricky to get a stable temperature.  AFAIK large temperature variations can still be a problem, as the voltage over temperature  looks like a parabola. To get a really stable voltage one still needs to be within some 5 K of the maximum.

The noise looks good - the big problem is that a direct measurement gives the combined noise of the DUT and reference inside the meter. It looks like the R6871E has a low noise reference. Chances are that much of the noise is from the meter and not so much from the DUT.
For a more stringent test, one may have to use 2 of the zeners and measure the difference.
 

Offline dietert1

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #634 on: February 04, 2021, 05:56:57 pm »
Does this noise determination include the R6871E noise or is this a difference between two low noise references? As far as i understand it should be very easy for you to build a setup with two such references and the R6871E as a null meter.

By the way, the standard deviation of 0.29 uV means about 0.041 ppm of 7 V. Looks familiar - the two LTFLU references i made in Mai 2020 give about 0.030 ppm when looking at hourly and daily averages. In addition they exhibit drift processes that one wouldn't call noise. As far as i know a LTZ1000 performs similar as long as you forget about the price. So one might assume the noise of one zener can be as low as 0.02 ppm = 0.03 ppm / Sqrt(2)

Regards, Dieter
 

Online serg-el

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #635 on: February 04, 2021, 09:51:47 pm »
If you looked closely at the figures, you might have noticed that the last measurements were taken with the ADVANTEST R6581.
From R6871E at 50 samples, the standard deviation is 0.51 μV.
 

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #636 on: February 04, 2021, 10:21:18 pm »
From the early parts of this thread, there are reports the a good sample of the 2DW233 can be even lower noise than the LTZ1000. In addition the direct measurement also adds some noise from the ADC. Even at 100 PLC the noise may be relevant here.  The R6581 does not seem to be so very low noise . It is still not bad and the ADC also has some good aspects when it comes to noise. However there is also 1 weak point.

With 30 Zener diodes to start with it should be possible to possible to build 2 references to compare.

 

Offline dietert1

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #637 on: February 04, 2021, 10:59:37 pm »
Thanks, now i can see the 100 nV steps. Don't know the Advantest instruments well, but the DVM seems to be very stable over several hours. In the case of our two LTFLUs i am logging the difference voltage with a HP 3456A in the 100 mV range, at the same resolution of 100 nV. Recently i cleaned the fan of that DVM and it shifted it's zero adjustment by 0.7 uV (in Autozero mode).

Regards, Dieter
 

Offline GigaJoe

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #638 on: February 13, 2021, 05:08:40 am »
I have approx 20 diodes , running at 10-15 mA ; all of them was thermally isolated and selfheated to approx 80-90C . Run it for 2 years. I finally disassemble setup, and set 1 can ( 2 diodes in parallel ) with current  adjustment to minimal temp-co (approx 0.3-0.5 ppm\C )  It runs a week as prototype without any PPM changes.
 
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Offline pico61

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #639 on: May 13, 2021, 11:07:25 am »
Hello everybody,
after reading all the posts I wanted to try to experiment with 2DW23X zener references too.
I found a seller on AliExpress who offered them at a low price, around 18 € for 20 items, including shipping.
I had bought 20 2DW232s but, after the purchase, he informed me that he only had 2DW235s available.
The latter, according to the datasheet, should work with a nominal current of 15mA, in my opinion too high due to self-heating but then reading what zlymex wrote, I bought them anyway.
After about a month, they were delivered to me.
The first thing I checked was the presence of the diamond symbol on the case.
I started testing using a Keithley 220 current source and a Fluke 8846A multimeter.
I state that at least in this phase I am only interested in verifying stability rather than low noise, not having suitable instrumentation to evaluate it.
At first I set the generator to 15mA.
I tried to heat the zener to a temperature of about 50 ° C. I detected a large variation in the voltage, then I tried to increase the current in steps of 1 mA up to 30mA but without significant changes in the Tc. So I tried with lower currents, always with steps of 1 mA, up to 5mA.
I found two things: the first is that around 7mA the TC decreased (but I have not been able to investigate further) and the second that over 10mA the zener tended to self-heat.
Then, I wanted to try lowering the current to just 2mA. Amazed I discovered that the Tc was almost zero! I tried to heat it up to 80 ° C (from 23 °) and I got a variation of less than 100uV. I tried again to reduce the current down to less than 1.5mA and I discovered a feature: the Tc is reduced to zero with a positive value (+ temperature, + voltage) up to a current of 1.56mA. With lower values ​​it becomes negative (+ temperature, - voltage). For this it was easy to discover the point at zero TC.
The detected voltage, at a current of 1.56 mA, was 5.24792V.
I tried to leave the 2DW235 plugged in for twenty four hours and the variation was 20uV (5.24794V - less than 4ppm) with a room temperature going from 23 to 25 ° C. However I can't be sure if the variation is due to the zener reference or the F8846A or due to current variations of the K220.
I tried to switch it off and then back on several times, even several hours later, and the maximum variation was only +/- 10uV (+/- 2ppm).
I have some questions:
- has anyone already detected this behavior of the 2DW23X?
- could they be used with out-of-specification currents? And the behavior regarding noise at such low currents?
« Last Edit: May 13, 2021, 11:21:57 am by pico61 »
 

Online Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #640 on: May 13, 2021, 01:16:22 pm »
A voltage of 5.25 V to get a low TC suggsts that this would be for only 1 zener, and not with both zeners in seires in the usual compensation way.  It is normal to get a low TC for only 1 zener at a much lower current that for the series connection.
 

Offline pico61

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #641 on: May 13, 2021, 01:33:25 pm »
A voltage of 5.25 V to get a low TC suggsts that this would be for only 1 zener, and not with both zeners in seires in the usual compensation way.

Yes the experiments were carried out only on one of the two zener in the case and only on three, of the twenty 2DW235 purchased, with voltages that varied between them by a few tens of mV.
 

Offline LHT5631080

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #642 on: June 15, 2021, 06:37:24 pm »
    Someone at 38HOT forum pointed out that it (2DW232) is more suitable for use under constant temperature conditions. The test conditions given in the specification are 25 degrees Celsius-75 degrees Celsius, which seems to indicate that it is not suitable for normal temperature use. Don't try to use a current far beyond its rated current in order to expect a TC.
    Under certain temperature conditions (for example, 50 degrees Celsius), a lower temperature coefficient can be obtained by adjusting the current around 5 mA-the test results of POCO61 have actually demonstrated this. 38HOT forum netizens make a voltage reference, and the 2DW232 internal 2 voltage regulators used in it are used in series instead of using one of them.
« Last Edit: June 15, 2021, 06:40:31 pm by LHT5631080 »
 

Online Kleinstein

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Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Reply #643 on: June 15, 2021, 08:49:34 pm »
Using a stabilized temperature makes a lot of sense, as the 2nd order TC is relatively high. Even if one adjusts the current to get a low linear TC, this is only valid for a limited temperature range.

The 2DW232 have widely scattering parameter. So it is not like an 1N829 - more like a random pic from 1N821 - 1N827. For the series configuration it may just need a lot (too much also at a higher temperature) of current to get a low TC. Those diode are better used as single Zener with a lower current to get a low TC this way. So it depends on the units if they are more suitable to use as a single diode at a relatively low current or with 2 in series with compensation. There can be some that do not work well in both mode (e.g. need >10 mA in series and <<1mA as a single diode).
So ideally one would get better screed ones, so one knows which circuit there is suiteable for. The situaltion with the 1N821 / 823 is also not ideal - it may be nice to know if the TC is positive or negative, they are likely testing them and could keep them separate.
 


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