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Suppose supplier of NTC shut-down the production for the NTC series. In this case if I am unable to find exactly the same component but rather found close match (by comparing B value @ R25/R100), then what are the parameters I should look in the new component so that it can best fit in my project without any glitch.

I saw in the datasheet R-T curve and temperature coefficient of resistance (alpha). However, I could not understood how alpha values were derived. I made several attempts to calculate alpha based on (https://www.ametherm.com/thermistor/ntc-thermistor-calculating-the-temperature-coefficient-of-a-thermistor) but I failed to get values mentioned in datasheet (NCP03XH103J05RL).

I tried to plot R-T curve using given resistor value and tried to derive ADC value also and compared both but not sure if this is the correct way!

Example of NTC circuit:

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ If it's an important application and you are worried about future availability, use an RTD and redesign the circuit accordingly. There is so much more correlation between suppliers/manufacturers of RTDs than NTC thermistors. \$\endgroup\$
    – Andy aka
    Commented Nov 19, 2020 at 17:35

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Resistance at 25°C and \$\beta\$ should be enough, however \$\beta\$ needs to be specified at the same two temperatures. To compare two parts with betas specified at different temperatures from the original you'd have to do some calculations.

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  • \$\begingroup\$ Thank you @Spehero Pefhany for your answer. Shouldn't I compare R-T curve from both NTCs to see if they are drifting too much from the original value or B value (R25/R100) comparison as you mentioned will be sufficient? Considering that I do not want to adjust the ADC values to fit new component. \$\endgroup\$
    – APX100
    Commented Nov 19, 2020 at 17:19
  • \$\begingroup\$ Beta and R0 define the response well enough in most cases. If Steinhart & Hart coefficients are specified you can use those to do calculations but it sounds like your original part does not have those specified.There are tolerances on both R0 and beta, which you should pay attention to. Tolerance on beta has a large effect at temperatures far from 25°C. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Nov 19, 2020 at 17:32
  • \$\begingroup\$ Can you please point out to any calculations/graph. I want to see how calculation considering tolerance is done. Thank you. \$\endgroup\$
    – APX100
    Commented Nov 19, 2020 at 19:44
  • \$\begingroup\$ en.wikipedia.org/wiki/Thermistor is fine. You can do the calculations in C, Python or even with an Excel spreadsheet. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Nov 19, 2020 at 19:49
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    \$\begingroup\$ If you're just looking for a substitute, however, you would normally just specify a part with the same nominal characteristics and equal or better tolerances. No calculations required. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Nov 19, 2020 at 20:07

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