cheap voltage reference over temperature

[yarayara]

Hi,

I want to build a cheap voltage reference for a circuit. I normally use a ZR431LF1 (Zetex voltage regulator), but I find it quite expensive.

I though about using a Zener diode with a voltage follower, but it might not be reliable over temperature (-40 to +90°C).

How can I build a voltage reference with a good performance over this temperature range?

Thanks!
yarayara

 

[analogkid2digitalman]

How is good performance defined?

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

 

[VEBill]

Here's a link to RAP's Bandgap article:

http://www.national.com/rap/Application/0,1570,24,00.html

You might find it useful.

 

[benta]

The TL431 available from several manufacturers is around 10 cents. Is that too expensive?

 

[yarayara]

Good performance would be 5%

The link looks good!

10 cents is cheaper than the 33cents I pay for the Zetez, but the operating temperature of the TL431 is from -25 to +80°C. My applications requirement is from -40°C to +90°C :/

But thanks anyway.

 

[nbucska]

For automotive application a temperature control may be cheaper.

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[IRstuff]

I don't understand the problem. The TI website shows parts ratings from -40ºC to +125ºC:

http://focus.ti.com/docs/prod/folders/print/tl431.html

TTFN

 

[yarayara]

trying to save money...
saving saving saving.

its cheaper to buy the chip. I build a better circuit, but its more expensive =/

I guess a Zener diode is fair enough for a non critical application.

Thanks everybody.

 

[emmgon]

You can try first building a simple zener voltage regulator circuit, which may cost around less than 10 cents and try to see if your circuit will work in the range of temperatures you are concerned of.

How many volts is your reference voltage?