Thermocouple Cold Junction Compensator and Matched Amplifier

The LTK001 is a thermocouple amplifier supplied with a matched cold junction compensator. By separating the amplifier and compensator functions, the problem of compensator temperature rise is virtually eliminated. The compensator is a selected version of the LT1025 cold junction compensator. The amplifier, which is also available separately as LTKA0x has been specially selected for thermocouple applications. It has low supply current to minimize warmup drift, very low offset voltage (<35µV), high gain, and extremely low input bias currents (<600pA) to allow high impedance input filters to be used without degrading offset voltage or drift.

Matching of the kits is accomplished by separating the compensators and amplifiers according to the polarity of their initial (room temperature) errors. This eliminates the need to sum the errors of the two components to find the worst-case error.

The LTK001 has direct thermocouple outputs of 60.9µV/°C (E), 51.7µV/°C (J), 40.6µV/°C (K, T), and 5.95µV/°C (R, S). It also has a 10mV/°C output which can be scaled to match any arbitrary thermocouple.

For multiple thermocouple applications using one compensator, amplifiers may be ordered separately (LTKA0x), still matched to the compensator.

Applications

* Thermocouple Cold Junction Compensation

* 0.75°C Initial Accuracy (A Version) * Extremely Low Warmup Drift * Preset Outputs for Type E, J, K, R, S, T * Single 5V to ± 20V Operation * 480µA Typical Supply Current * Available in 8-Pin DIP Package