accurate power supply

[rudie]

Hello guys,

I am making a circuit to measure a temperature(pt1000) with some accuracy. The circuit i made works. It has an accuracy of 0.25 degrees. The circuit also needs a supply voltage, but i can find a voltage regulator that as a great accuracy.

I want a 5V supply. But if i look on the internet i can find some voltage regulators that have a line regulation of 0.01% that is good enough because the maximum difference in output would than be: 5*1.0001=5.0005. But is that the only parameter that determines the accuracy of a voltage regulator. I guess not, but which ones are also important? Or is there an other way to make the supply voltage to the pt1000 very accurate. It would be nice if this could be done with an accuracy of approximately 1mV.

i hope that someone can help me

greets rudie

 

[neo79]

and the load regulation, temperature shift, etc

 

[IanP]

mate,
use the old [but still the best] µA723 ..
rgds,
ianp

 

[FvM]

Normally, you would use a voltage reference rather than a common voltage refgulator, if the said accuracy is required. A 5.0 V reference would be available with very high accuray and also low temperature drift (e. g. a few ppm/K).

For a Pt1000 measurement, the accuracy is only needed, if the measurement output must be an analog value, e. g. to connect a external acquisition device. If you are digitizing the temperature in the same circuit, Pt1000 measurement can be reduced to a resistance ratio measurement, that won't need a precise reference at all, just a low noise supply.