PT100 RTD Temperature Sensor Amplifier with I2C output

Other Hardware Sensors
1

Hello,
can anybody advice me for a temperature PT100 sensor / amplifier with an I2C output.
I currently use the MAX38165 but this one talks SPI.
Thanks for your help.
Regards

2

How about MAX6698? Not a perfect match but should work.

3

Thanks for your quick answer.
I am not a specialist in electronics but it seems I have to apply some additional parts for the PT100 and the input to this IC. Am I right here ? How does the circuit look finally ?

4

What exactly is your use case? Depending on the circumstances you might not even need an amplifier at all.

The MAX6698 just needs some resistors to work with the RTD (other than the decoupling), according to the datasheet (I never used it myself).

5

I just need to connect an PT100 (two wires) to the Arduino and want to use the I2C protocol. The MAX38165 already has an amplifier circuit onboard and knows how to 'translate' the resistance to temperature. However, as I said, it uses SPI to communicate.

6

What’s the temperature range - 2wire connection to a prt , unless wires are very short will have errors from the lead resistance .

7

Temperature range is -10 °C ... 100 °C. Length of wires is about 50 cm.

8

If you use a Ds18b20 it will
Accurately cover the range , is a digital sensor and needs no amplifier

9

I know the DS18B20 but it doesn't meet my requirement of having the PT100 as a sensor.

10

I know the DS18B20 but it doesn't meet my requirement of having the PT100 as a sensor.

Might we ask why this is a requirement? And why is I2C a requirement?

11

I got a PT100 which already is mounted in a stainless steel tube which has the exact diameter for mounting it in a vessel.
Most of the 'wrapped' DS18B20 are larger in diameter (6 mm). I need 4 mm.

12

PT100 sensors are synonymous with accuracy. It would be good to verify the SPI cannot be used before degrading the PT100 output with a lesser circuit. Especially since you only have to read the SPI not write.

In addition the 31865 uses 4 wire sensing which will cancel out the resistance of the cables.

Keep in mind a PT100 sensor only changes by 0.39 ohms/°C

13

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