There is no single NTC thermistor chart that applies to every model. Each thermistor has a resistance–temperature (R/T) characteristic, and the useful values depend on the exact part, reference resistance, tolerance and specified temperature range. Use the manufacturer’s datasheet for the selected model rather than a generic chart.
How to read an NTC resistance–temperature table
Start with the part number and datasheet revision. Check the rated resistance and its reference temperature, then read the R/T table at the temperatures relevant to your design. Confirm whether resistance is stated in ohms or kilohms, and whether the table lists nominal values, tolerance limits or both.
Some datasheets also provide a beta value for a stated pair of temperatures. Beta is interval-specific; it is not a universal constant for all NTC models or temperature ranges. TDK’s technical information describes the exponential approximation and notes that actual applications use the model’s specified R/T data. Consult the TDK NTC thermistor technical guide for background.
What a generic chart cannot tell you
- The resistance curve or tolerance of a different NTC model.
- The rated temperature associated with a nominal resistance unless the datasheet states it.
- The sensor’s permitted operating range, accuracy in the final assembly or response time.
- Whether a probe, chip or leaded thermistor matches your mounting and environmental conditions.
- The effect of measurement current and self-heating in your circuit.
Use the chart with the controller input
After selecting the correct R/T values, verify that the measurement circuit and firmware use the same curve. Review the pull-up or reference network, ADC input range, conversion method, calibration points, wiring and fault detection. Where a beta approximation is used, confirm its reference resistance, reference temperature and beta interval against the datasheet and validate it over the required operating range.
A resistance reading at one controlled temperature can help check incoming parts, but it does not verify the full curve or the installed sensor’s system performance. Validate representative samples in the finished assembly and under the intended thermal conditions.
OEM NTC selection checklist
- Exact part number and datasheet revision.
- Rated resistance, reference temperature, tolerance and R/T table.
- Beta value and temperature interval, if used by the conversion.
- Required temperature range, measurement accuracy and calibration points.
- Sensor package or probe dimensions, mounting, lead length and connector.
- Controller input, circuit conditions, self-heating limits and environmental exposure.
For specific resistance values, see our 10k NTC selection guide and 100k NTC selection guide. Browse the NTC thermistor range or send your R/T curve and assembly requirements for an OEM quote.
