Re: Low voltage zener diodes

On Wed, 9 Oct 2024 01:40:46 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:

On 08-10-2024 07:25 pm, Jan Panteltje wrote:

On a sunny day (Tue, 8 Oct 2024 14:54:39 +0530) it happened Pimpom
<Pimpom@invalid.invalid> wrote in <sT6NO.84691$Xx4a.59580@fx11.ams1>:
 

When I tested some low voltage zener diodes (<<5V) 30-40 years ago, I
found that they didn't have even a reasonably sharp knee, behaving more
like LEDs in forward mode, maybe worse. Do I remember correctly? Are
they still the same?

 
Yes.
These days there  are 'bandgap' references, those are about 1.25V,
extr3mely stable.
  https://en.wikipedia.org/wiki/Bandgap_voltage_reference
You can also use a chip like TL431 (google TL431.pdf)
to make a reference from about 2.5 V upwards
to whatever you like with 2 resistors as voltage devider.
IIRC it uses that bandgap reference principle.
  https://en.wikipedia.org/wiki/TL431#Applications
 
 

I have a bunch of TL431, LM385 (1.25, 2.5 & adj.) and LM4040 references.
But somehow these high precision, high stability references somehow feel
like overkill in certain situations. It's not the cost, it's the
appropriateness.
>
I remember the first time I used an LM385. I live in a very remote, very
hilly part of India.

Sounds interesting. What are the coordinates?