temperature measurement

Forum 2005-2010 (read only) General Bar Sport
1

Hello,

I am searching a chip that can convert temperature into digital data, the sensor will be a thermocouple

range: -40 to 80 degrees Celsius or wider

accuracy: up to 2 decimal digits

Do you have any suggestion?

I am going to start a project for making a temperature controller with precise temperature sensing, and to be used in laboratory environment

Joseph

2

I am going to start a project for making a temperature controller with precise temperature sensing, and to be used in laboratory environment

Generally thermocouples are not the best choice when precise measurement is desired. Thermocouples main advantage is lower cost sensor and the ability to read and survive to a couple of thousand degrees. In your desired measurement range an RTD sensor is consider the 'gold standard' for lab use. Both types require some interface circuitry or interface chip.

http://cgi.ebay.com/0-2-Class-A-Platinum-Resistance-Thermometers-PT100_W0QQitemZ350325797744QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item51910b7370

Lefty

3

Hello,

I'll try to use RTD type sensor.

Do you have any advice on choice of IC to use?

Joseph

4

Hi,

I googled a bit, and found a design using 3 lmp2011 precision op amp. I don't know if there's any single chip solution?

Joseph

5

You might try reading through the below posting from the AVRfreaks forum. Lots of other good backround information about RTDs.

http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=329999

Lefty

6

search for instrumentation amplifier ic on google
you shold get many hits, TI, National...
national has a scematic here
http://www.national.com/nationaledge/dec04/article.html

7

Thanks Lefty and ArduinoM,

It seems there are quite many instrumentation op amps out there. I am now comparing them. There's one circuit design which claim to achieve 0.01 deg accuracy with proper calibration. This looks very promising

Cheers

Joseph