Curve selection matters
The best R/T curve depends on response time, application temperature range, and finished coated dimensions.
Named by NTC value
North Star Sensors R/T curves are named after the negative temperature coefficient at 25 °C.
Engineering guidance available
Application engineers can help select the optimal curve material for the application.
North Star Sensors offer six R-T curves to select from. Which R-T curve to select depends on a variety of parameters such as response time, application temperature range, and finished coated dimensions. If needed, North Star Sensors application engineers will help you select the optimal R-T curve material for your application.
North Star Sensors R-T curves are named after the NTC (Negative Temperature Coefficient) value at 25 °C. For example, Curve 44 has an NTC value of -4.4%/°C at 25 °C.
Use the comparison chart and the per-curve reference files below to move from quick curve selection into detailed ratio tables, R/T specifications, and calculator files.
Key Details
- Curve 44 is one of the most versatile and widely specified materials
- Curve 44 commonly spans 1 kΩ to 100 kΩ
- Curve 35 supports lower resistance ranges from 50 Ω to 500 Ω
- Curve 38 typically spans 100 Ω to 1.5 kΩ
- Curve 40 10 kΩ devices are widely used in several industries
| Curve: | 44 | 35 | 38 | 40 | 43 | 47 |
|---|---|---|---|---|---|---|
| 0 °C / 70 °C Ratio: | 18.65 | 10.38 | 12.96 | 14.82 | 17.73 | 22.64 |
| 25 °C / 85 °C β: | 3978 | 3192 | 3486 | 3694 | 3943 | 4262 |
| Resistance Range: |
1 kΩ - 100 kΩ | 50 Ω - 500 Ω | 150 Ω - 1.5 kΩ | 5 kΩ - 50 kΩ | 20 kΩ - 50 kΩ | 10 kΩ - 150 kΩ |
Go to page Calculating Temperature from Resistance for more details about Ratio and Beta value β.
Curve Reference Files
Use the per-curve downloads below for detailed 1 °C Rt / R25 tables, full R/T specifications, and resistance-versus-temperature calculator spreadsheets.
Curve 44
Versatile across common package styles
One of the most versatile and widely specified materials, Curve 44 is available in standard tip, mini, and micro OD configurations.
Curve 35
Useful for lower resistance, low-temperature work
Curve 35 is commonly selected for lower resistance values and is especially useful for low temperature measurement applications.
Curve 38
Low-temperature option with a broader resistance span
Like Curve 35, Curve 38 is well suited for low temperature measurements while covering a higher typical resistance range.
Curve 40
Popular 10 kΩ material in established applications
The Curve 40 10 kΩ thermistor is widely used in several industries and supports a familiar mid-range resistance window.
Curve 43
Higher resistance in smaller thermistor formats
Curve 43 is used where a high-resistance, smaller-sized thermistor is desired, while still allowing some lower custom values when needed.
Curve 47
Strong fit for low-power, battery-focused designs
With R25 values reaching as high as 150 kΩ, Curve 47 can be a strong option for lower-power applications, including battery-powered designs.