Hey, Currently I am using this " https://www.ti.com/lit/ug/tidu969/tidu969.pdf " for reading my PT-100 circuit. Can I use this same circuit with a three-wire PT-1000 application with or without any modification.
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Hey, Currently I am using this " https://www.ti.com/lit/ug/tidu969/tidu969.pdf " for reading my PT-100 circuit. Can I use this same circuit with a three-wire PT-1000 application with or without any modification.
Hi
Can I use this same circuit with a three-wire PT-1000 application with or without any modification?
Yes, you may. Below is the application notes in Ratiometric 3-Wire RTD Measurement.
Due to PT1000's resistance of 1kΩ at 0ºC and 5Vdc single supply rail, the circuit is unable to have larger gain. The example below has a gain = 12.5 V/V. and Vref = 2.5Vdc at pin5. The Thevenin resistance is 250kΩ and Thevenin voltage is 0.5Vcc. The RTD example is simulated from -30C to 100C and you may scale the circuit accordingly. You may decrease Vref slightly and increase the circuit gain to have wider voltage span, if necessary.
https://static5.arrow.com/pdfs/2013/11/24/3/19/23/744/txn_/manual/slau520.pdf
INA326 3lead PT1000 08032021.TSC
If you have additional questions, please let me know.
Best,
Raymond
Hey, I attached my PT-100 circuit above. Can you please verify one thing why do we need Vref at R2 on INA326A.
Check my PT-100 circuits that are working without any ref voltage. Ref voltage is just needed when we going to convert the analog to the digital value.
Hi Dheeraj,
Can you please verify one thing why do we need Vref at R2 on INA326A?
For 2 wire RTD temperature measurement, I think that this is what you have based on the simulation from 0C - 125C or 100Ω - 147.9Ω.
If I check the INA326 with Analog's Engineering Calculator, this looks ok. If you place the Vcm at 2.5Vdc, Vout will have slightly more output range under 5V single supply rail.
INA326 2lead PT100 08042021.TSC
If you have additional questions, please let me know.
Best,
Raymond
How can I increase our voltage range, currently it is between 3.6 to 4.24 but I have to increase this range without adding noise to the circuit.
Hi Dheeraj,
Using the same method shown in the " https://www.ti.com/lit/ug/tidu969/tidu969.pdf " application note. The plot is simulated from 0-125C or 1kΩ - 1.48kΩ
Enclosed is the simulation:
INA326 3lead PT1000 08042021.TSC
Best,
Raymond