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Current reference REF200

Hi all, I'm taking over someone's circuit. The schematic has an REF200 in it. I'd never seen this IC before. Two sources and a current mirror.

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In this schematic the current sources are just turned into voltages. (by passing through a TIA opamp circuit.) I'm thinking of pitching the whole thing and using some nice voltage references to start with. (like an ADR02ARZ) But before I do I thought I'd ask here. Is there some advantage to the current source as a reference?

George H.

Reply to
George Herold
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That sounds really weird. The unit price of that part is over $6.

Do you need precision and low TC? REF02s are cheap. LM4040s are dirt cheap.

We like the ADR3xx and ADR4xx parts for precision refs.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Cost comparison? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Yeah I've used lotsa REF02's and some LM4040's .. so those are all in stock and cheaper!

The guy was hired on for a few months. He did a lot of high impedance stuff before.. probing cells and stuff... so maybe there is some use for a current source in the high impedance world?

Anyway I'm giving myself permission to redo the whole thing.

George H.

Reply to
George Herold

Yeah the current source is at least twice as much... (not counting the precision R and opamp.) You do get two of them.

George H.

Reply to
George Herold

The REF200 with its low current of 100uA is perfect to create small voltages in the mV range for example for offset compensation in amplifier circuits (figure 24 in the datasheet). It is also very useful for floating (not referred to ground) reference voltages. If on the other hand, it is really used to create a reference voltage of a few volts referred to ground, you are most likely better off with a voltage reference, both with regard to performance and price.

Klaus

Reply to
Klaus Bahner

Resistive voltage dividers can do that too.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

It's a pricey chip because the whole thing is dielectrically isolated; they oxide-covered a wafer, grew the silicon by chemical vapor deposition, and later etched it back so the three sections are islands.

If you want ppm-symmetry for a square wave (fig 17c) , it's a dandy part.

Reply to
whit3rd

Thanks Klaus I figured they must have some use. Re: floating, I've never had a problem floating a good voltage reference... or something like the lm4040 or other diode reference.

George H.

Reply to
gghero27

Oh excellent! I saw that bidirectional current source and thought... WTF... how is that?

George H.

Reply to
gghero27

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