Author Topic: ADR1000 availability  (Read 22854 times)

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Online Kleinstein

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Re: ADR1000 availability
« Reply #100 on: September 12, 2022, 04:38:47 pm »
The eval board is odd: one of the advantages of the ADR1000 compared to the LTZ1000 is the lower importance of the temperature setting resistors.
With the LTZ1000 those 2 resistors were the 2 more critical ones. With the ADR1000 they no longer are: The resistors (e.g. 2x50 K) to set the transistor currents and the resistor ( ~120 ohm) to set the zener current are more relevant.

As the ciruit is essentially the same as with the LTZ1000, one could use one of the boards made for that reference. There are plenty designs around.

The cut outs around the reference make some sense, especially when running quite hot. It at least reduces stress from the PCB. The shape is a bit odd with relatively sharp corners the manufacturers usually don't like very much.
 

Offline Kosmic

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Re: ADR1000 availability
« Reply #101 on: September 13, 2022, 01:36:06 pm »
one of the advantages of the ADR1000 compared to the LTZ1000 is the lower importance of the temperature setting resistors.
With the LTZ1000 those 2 resistors were the 2 more critical ones. With the ADR1000 they no longer are: The resistors (e.g. 2x50 K) to set the transistor currents and the resistor ( ~120 ohm) to set the zener current are more relevant.

From the ADR1000 specsheet:


Did I miss something ?  :-// proportions seem to be similar to the LTZ1000. I would say R4/R5 are still important.
 

Offline Dr. Frank

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Re: ADR1000 availability
« Reply #102 on: September 13, 2022, 02:57:20 pm »

From the ADR1000 specsheet:


Did I miss something ?  :-// proportions seem to be similar to the LTZ1000. I would say R4/R5 are still important.

You missed the fact, that for the LTZ1000, R4 and R5 had a 75..100:1 ratio, so it's at least 2 times more relaxed here.
The un-ovenized LTZ1000 RefAmp has about +50ppm/K T.C., where this sensitivity arises from.

From scratch, the ADR1000 shows around 2..20ppm/K only, depending on oven temperature and sample variation, and you can even trim this to zero exactly at the oven set temperature, by appropriate selection of the collector current, like for the SZA 263 / LTFLU.
 In this case, this R4/R5 ratio becomes completely irrelevant, so you would need one or two stable stable resistors only, instead of five.

Frank
 
« Last Edit: September 13, 2022, 04:13:02 pm by Dr. Frank »
 
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Offline Kosmic

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Re: ADR1000 availability
« Reply #103 on: September 13, 2022, 03:22:10 pm »

From the ADR1000 specsheet:


Did I miss something ?  :-// proportions seem to be similar to the LTZ1000. I would say R4/R5 are still important.

You missed the fact, that for the LTZ1000, R4 and R5 had a 75..100:1 ratio, so it's at least 3 times more relaxed here.
The un-ovenized LTZ1000 RefAmp has about +50ppm/K T.C., where this sensitivity arises from.

From scratch, the ADR1000 shows around 2..20ppm/K only, depending of oven temperature and sample variation, and you can even trim this to zero exactly at the oven set temperature, by appropriate selection of the collector current, like for the SZA 263 / LTFLU.
 In this case, this R4/R5 ratio becomes completely irrelevant, so you would need one or stable stable resistors only, instead of five.

Frank

ok make sense, thanks  :-+
 


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