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LM431 (TL431) 0.1-10 Hz Vp-p noise.
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magic:
That's 1100nV/rtHz at 10Hz, so 25 of them will match TI TL431 and about 300 will match onsemi.

I don't know why onsemi is more efficient than TI, but as a general rule, noise is determined by the combined current of all references, not by how much you split that current into multiple chips ;)
iMo:
Sure, each reference with its own cathode resistor and combined via a summing resistors. As it is done with 399 when more pieces in parallel..
Thus 100 references, and 200 resistors (100*125k cathode ones and ie. 100*10k summing ones with 5V power)  :phew:
The total current will be ~2mA.

PS: those 1150nV/rtHz is for 100uA, thus with 20uA it will be even more. Anyhow, simply scale it up to 1000 pieces, still only 20mA total current  :D :D
magic:

--- Quote from: iMo on June 14, 2023, 09:11:45 am ---PS: those 1150nV/rtHz is for 100uA, thus with 20uA it will be even more.

--- End quote ---
You can try, but I doubt it.

The first 10μA (LM385) or 400μA (TL431) flows through the bandgap reference, the rest is bypassed by a power transistor in parallel with it.
Throwing more current at the chip increases power transistor bias and may reduce impedance and improve dynamic response, but I wouldn't expect much difference in noise.
They all ought to be OK at their minimum operating bias.
jmelson:
A really good low-noise reference is the LM4140.  Available with a few output voltages, noise is less when run from less than 4.5V, and you have to put about a 1 mA load on the output.  There might be even better ones now, but we found this one to work really WELL in a noise-sensitive application.
Jon
MasterT:
VN Output noise voltage(7) 0.1 Hz to 10 Hz 2.2 μVP
Charts 11 and 12 show about 200nV/sqrt(Hz), compare to 48nV TL431B
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