33µA constant current / 3.3V max source ?

[Otatiaro]

Hello,

What would be the best option to make a reliable, about 33µA (a bit higher, like 50µA, would be ok too) constant current source under max 3.3V, using small SMT components ?

Thomas.

[ejeffrey]

An opamp current source.  Google for it and you will find many examples.

There are other possibilities if you need special requirements, but this should get you started.

Even simpler would be a self-biased JFET current source.

[PA0PBZ]

This worked for me as a simple current source:

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          +-------+----+


[DaveW]

It's worth having a look at something like this as well if you need constant current over a wide range of loads. Make sure the op-amp has a low-ish input bias current though