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Yes, I see that and I should have thought of it..... MindSim failed!

That 1mA must be the minimum to power the onchip reference and opamp.

Oh well, back to the drawing board!

I suppose it could be done with a very low power CMOS opamp, plus a 5.1V zero TC Zener, plus a discrete npn BJT to replace the TL-431..... but I will have to noodle on that

I used to design such opamps but they were not available as discrete opamps........ they were buried in a VLSI processor, etc.

rogerw

I will look into that.

rogerw

On 4/5/2022 3:28 PM, peter via groups.io wrote:

Roger:
?This is what Geo was asking in lieu of a zener.?
Well, there may be a limitation due to minimum current requirements of the IC shunt regulator chip. I think the spec sheet notes about 1ma for lower limit (?)
Its adjustable up to ~+30V
(On a different not there some newer ones that go up to 125 volts or so,)

P

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rogerw
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ΜΟΛΩΝ ΛΑΒΕ

The PanDemic is over, but the DemPanic goes on.
MisDisMal is a dictator's tool of repression.