Current reference REF200

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.

Cost comparison? ...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.

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.

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

Resistive voltage dividers can do that too.

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.

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.

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

George H.