Current Reference (commercial component!)

[radiohead]

Hi,

I need to sink (from 5V to 1V) a temperature stabilized reference current, using some commercial integrated chip or simple circuit. I can find lots of voltage references, yet current references ...

Please provide simple solutions, the simpler the better. I'm not interested in analog circuits that can be implemented on chip, I can find these myself in a textbook.

Thanks

 

[VVV]

You can use this circuit.
Resistor R1 should have low tempco, the lower the better. 25ppm I would say should be the maximum.
The reference is one of your choice, but with a tempco of 10ppm is great.
The opamp does not have to be OP293, but something with low offset drift is necessary.
The MOSFET can be any MOSFET, as long as the leakage current is acceptable (low, compared to output current). It should be sized and/ or heatsunk adequately, depending on your output current and voltage compliance.
Resistor R2 is not critical, 1k to 10k should be just fine.