Products

Temperature measurement

High precision temperature measurement

For stable and accurate temperature measurement over a long period of time, the followings are required for the temperature sensor.

 

(1) Linearity of resistance change with temperature change

(2) Long-term stability of characteristics in operating temperature range

Linearity of resistance change with temperature change

KOA's platinum film temperature sensors have the superior linearity among the linear positive temperature coefficient resistors. Therefore, the temperature can be calculated from the resistance value using a function without using a conversion table.

Long-term stability

In order to measure the temperature with high accuracy, the rate of change of resistance value over a long period of time is required to be small. Platinum thin film temperature sensors have the advantage of having a smaller rate of change of resistance value than linear positive temperature coefficient resistors and thermistors.

In addition, KOA’s small platinum thin-film temperature sensors SDT310HCTP has a unique structure, resulting in a very low rate of change of resistance and excellent long-term stability.

e.g.

  • 300 ℃ 1,000 hours: +/- 0.06% (guaranteed value)
  • 400 ℃ 1,000 hours: +/- 0.12% (guaranteed value)

Wide temperature range measurement

KOA’s platinum thin film temperature sensor has a wide operating temperature range of -55 °C to + 650 °C. We also have a product lineup that guarantees the tolerance over the entire temperature range.

As shown in the figure below, a comparison between a thermocouple, which is a temperature sensor, and a platinum thin film temperature sensor shows that the platinum thin film temperature sensor is more accurate than the thermocouple in the temperature range of -55 ºC to + 300 ºC that is commonly used in industrial equipment and measuring instruments.

Temperature measurement (example)

* When measuring the temperature using a platinum film temperature sensor, the current should be low so that self-heating does not affect the measurement.

Connection method (example)

Generally, the platinum thin film temperature sensors measure the temperature with two-wire system, but by connecting with a three-wire or four-wire system, the effect of resistance from wires can be canceled. Three or four terminal connection is recommended for an accurate temperature measurement.

Temperature measurement circuit (example)

Platinum thin film temperature sensors

Item Series Product Name
SMD type SDT73H Platinum Thin Film Chip Thermal Sensors
SMD type SDT73S Platinum Thin Film Chip Thermal Sensors
(High heat resistance)
SMD type SDT73V Platinum Thin Film Chip Thermal Sensors (For automotive)
Axial lead type SDT101 Platinum Thin Film Thermal Sensors
Radial lead type SDT310 Small Type Platinum Thin Film Thermal Sensors
Radial lead type SDT310HCTP Small Type Platinum Thin Film Thermal Sensors (Narrow type)
Axial lead type SDT310VASP Small Type Platinum Thin Film Thermal Sensors (Small heater element)