High-precision temperature chip for measuring PT100 - Page 1
Forum section: electronics / general

author: BJ1023
author_rank: Newbie
timestamp: August 21, 2025, 02:45:31 pm
content: High-precision temperature chip for measuring PT100？

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2025, 06:51:00 pm
content: What kind of accuracy and precision are you expecting? 0.005C is possible but will require calibration.Do you want a specific ASIC or a signal conditioning circuit?

author: Jim Narem
author_rank: Contributor
timestamp: August 21, 2025, 08:52:31 pm
content: The MAX 31865 has a 15 bit ADC, it's mostly dependant on the reference resistor quality and tempco.

author: TUMEMBER
author_rank: Regular Contributor
timestamp: August 22, 2025, 08:29:48 am
content: Quote from: BJ1023 on August 21, 2025, 02:45:31 pmBut is this a complete device or an integrated circuit that you can build and program yourself?Please clarify. And what level of accuracy is expected?With a max 31865, don't expect accuracy better than 0.03 degrees (the resolution is higher, but the Pt100 curve representation is only 0.03). There's also the error of the sensor itself, which isn't "constant across the entire measurement range" because it's defined as a percentage of the currently measured value.Furthermore, "sensor error depends on its class and design"—2-wire, 3-wire, or 4-wire.https://www.jumo.pl/web/about-us/blog-pl/pt100-accuracy-classOr choose one of those "ready-made solutions", expensive but no need to mess around without a guarantee of success.https://digilent.com/shop/usb-data-acquisition/

author: voltsandjolts
author_rank: Unknown
timestamp: August 22, 2025, 10:03:06 am
content: $10 says the OP never returns

author: The_Dall
author_rank: Newbie
timestamp: August 22, 2025, 12:53:03 pm
content: Chip for PT100:LTC2983 - 24-bit ∆∑ ADC resolution 0.001°C.MAX31865 15-bit ADC Resolution 0.03125°C.You can also use the ADS1220 or AD7793 24-bit ∆∑ ADC using their built-in current sources.For high accuracy, the calculation of Callendar–Van Dusen coefficients is required, but then you need to find a temperature calibrator somewhere.

author: David Hess
author_rank: Super Contributor
timestamp: August 22, 2025, 07:19:38 pm
content: Quote from: The_Dall on August 22, 2025, 12:53:03 pmA 3 point calibration will get you to within 0.005C without worrying about the purity of the sensor, but this is not a trivial exercise.A 2 point calibration could get you to better than 0.5C, and maybe as good as 0.05C. I think I have gotten to within 0.1 using this method, but the boiling water part is tricky. I had to use a stainless steel mesh to keep the boiled water from touching the sensor.

author: Overspeed
author_rank: Frequent Contributor
timestamp: August 26, 2025, 02:48:07 pm
content: Quote from: David Hess on August 22, 2025, 07:19:38 pmHelloOk for the 3 points of calibration but that request to have an access to real calibration system , 0.005 deg C is in range of triple point cell , water 3 points is easy to locate even can be built DIY but after for highter temp that far more difficult and costlyThe other solution is work by comparison with a metrology probe / thermometerTake in consideration that water boiling point is linked to the atmospheric pressure so reach 0.005 deg C of accuracy is a ..... dreamBefore to plan to calibrate , first step is to know what range of temp you need / want calibrate a 0 deg C to 100 deg C is far more easy that a 0 to 400 deg C .RegardsOS