[volt-nuts] Best Vref part ?

[Fred Schneider]

I want it for two reaons, just make several for fun as experiment and indeed the best one as a ADC reference. Ok thanks, I will look if the sell the LT1027 too. But it is not heated, is a LM399 the only heated Vref ? Because for a LT1027 i have to make an oven.

Fred PA4TIM

Op 30 sep. 2011 om 23:50 heeft "Andreas Jahn" <Andreas_-_Jahn at t-online.de> het volgende geschreven:

> Hello Fred,
> 
> do you want to have a stable voltage (calibrator) or do you
> want to use this reference with an ADC for precise measurements?
> 
> I tried many 5V-references for an 24Bit LTC2400 ADC.
> From LT1027, LT1021 and LT1236 the LT1027 is the best.
> Similar performance I have found with a MAX6250A but
> my device seems to have some popcorn noise of around 1-2 ppm.
> 
> I use a simple NTC temperature sensor to do a 3rd order
> polynomal compensation of the tempco of the reference.
> (see picture on 09.09.2011 in this list).
> 
> I use LT1027CCN8-5 references and the stability after ageing
> is mainly determinded by relative humidity. (0,4 ppm / % rH)
> after having calculated the tempco out of the reading.
> Ageing is less than humidity influence during the last year.
> The references are now running since 3 years.
> 
> To get humidity factor off  I buyed 2 hermetically tight
> VRE3050AS from Digikey. But with my 2 devices
> have horrible noise (factor 3-5 over LT1027).
> Hysteresis I have measured on the first of the
> 2 VREs and found 4-5ppm compared to
> the LT1027 with about 1-2ppm.
> 
> With best regards
> 
> Andreas
> 
> ----- Original Message ----- From: "Fred Schneider" <pa4tim at gmail.com>
> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Sent: Friday, September 30, 2011 9:49 AM
> Subject: [volt-nuts] Best Vref part ?
> 
> 
>> I want to make some good ( better then the ones I made) Vrefs. Better as in longtime stability and tempco. Just for fun.
>> The ones I made upto now have a short time drift of 1 to 3 ppm, longtime ?? They are on for a month now, and begin t ostabilize.
>> I have the schematic from Warren that uses the 1n825, i can buy that from Farnell.
>> I have a schematic that uses a LT1021B, also for sale at Farnell.
>> But I have read about LM199/299/399 that is temperature controlled
>> LTZ1000 that should be very good and VRE4100 but non of those sold by Farnell.
>> What is the best option ? I am not a company so I can not order evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay acount because I do not like auctions and bidding.
>> 
>> Fred PA4TIM
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> 
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