Measuring negative temperature with PT 100

[anujaa]

Hello All,

I want to interface the PT 100 to meshnetics module(Zigbee wireless platform).
This module has inbuilt ADC.

The temperature range is -20 ºC to 400 ºC.
Right now I am using Wheatstone bridge with INA326 instrumentation amplifier.
This works well with Range of 0ºC to 400 ºC
So, What changes should I made to measure negative temperature?

Regards,
Anujaa

 

[laktronics]

Re: PT 100 Sensing

Hi,
You can either balance the bridge , or adjust the amplifier offset to zero at -20° and reduce the gain by 5% to accommodate a range of 420°. Then, from the measured value you subtract 20° and display the value.

Regards,
Laktronics