Micropower Thermocouple Cold Junction Compensator

The LT1025 is a micropower thermocouple cold junction compensator for use with type E, J, K, R, S, and T thermocouples. It utilizes wafer level and post-package trimming to achieve 0.5°C initial accuracy. Special curvature correction circuitry is used to match the "bow" found in all thermocouples so that accurate cold junction compensation is maintained over a wider temperature range.

The LT1025 will operate with a supply voltage from 4V to 36V. Typical supply current is 80µA, resulting in less than 0.1°C internal temperature rise for supply voltages under 10V. A 10mV/°C output is available at low impedance, in addition to the direct thermocouple voltages of 60.9µV/°C (E), 51.7µV/°C (J), 40.3µV/°C (K, T) and 5.95µV/°C (R, S). All outputs are essentially independent of power supply voltage.

A special kit is available (LTK001) which contains an LT1025 and a custom tailored thermocouple amplifier. The amplifier and compensator are matched to allow a much tighter specification of temperature error than would be obtained by adding the compensator and amplifier errors on a worst-case basis. The amplifier from this kit is available separately as LTKA0x.

The LT1025 is available in either an 8-pin PDIP or 8-pin SO package for temperatures between 0°C and 70°C.

Applications

* Thermocouple Cold Junction Compensator

* Centigrade Thermometer

* Temperature Compensation Network

* 80µA Supply Current * 4V to 36V Operation * 0.5°C Initial Accuracy (A Version) * Compatible with Standard Thermocouples (E, J, K, R, S, T) * Auxiliary 10mV/°C Output * Available in 8-Lead PDIP and SO Packages