If anyone knows of a shunt regulator that operates below 1 Volt on all
terminals* I'd be interested to hear of it. If it costs less than the TL423=
D
I describe below I'd be very interested.
(The NCP100 qualifies on voltage but not on price or easy availability). (*
ie some parts have Vref < 1 V but have a minimum Cathode voltage of several
volts).

The TL431 2.5 V shunt regulator is possibly the worlds lowest cost IC - and
also very handy.
Typically regulates at 800 uA and above.

The TLV431 is a 1.25 V version. usually with lower maximum voltage rating
but also usually comes into regulation at under 100 uA.

Until now I had not met the 0.8 V TL432D variant, made possibly only by
Unisonic.
It has a 0.8V reference and can regulate with Vcathode as low as Vref =3D
0.8V.
This can be crucial when working with low voltage (eg single cell) circuits=
..
A 0.8V reference can be driven from a single NimH cell - whereas a 1.25V
part cannot.
There are other sub 1V band gap references but most either need a higher
cathode voltage or have other limitations.
When/if you want something that "just goes" at down to 0.8V this part looks
good.
Price unknown yet but hopefully in Asia will be < 10 cents in volume.
(TLV431 variant (actually a LRC432) costs about 3 cents in volume.

                 http://www.unisonic.com.tw/datasheet/TL432D.pdf

Disadvantages inc;lude low Vmax and needing 1 mA minimum for regulation but
those are entirely bearable in my applications.


 Russell
--=20
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