Temperature Controllers

Laird's temperature controllers are specifically designed to control thermoelectric assemblies, (TEAs) in a closed loop system. Feedback from a temperature sensor is used to vary the output of the power supply to control the temperature of an enclosure. Laird offers three types of controllers: Single Directional Thermostatic, Bi-Directional Thermostatic, and Proportional Integral Derivative (PID) (Programmable).

A Single Directional Thermostatic Controller can maintain a constant temperature set point within an enclosure surrounded by a relatively constant ambient temperature. The set point tolerance is defined by a hysteresis range. Once the set point is achieved, the controller shuts off the TEA. When the control temperature changes to outside the hysteresis range, the controller turns on power to the TEA and restarts the cooling mode process. This cycle continues until the controller is shut down. Thermostatic control is often used in refrigeration mode in an indoor environment with climate control, where a narrow temperature swing can be tolerated. Laird offers two standard single directional thermostatic temperature controllers, QC-50 and QE-50.

A Bi-Directional Thermostatic Controller operates in the same manner as a Single Directional Controller, except output can operate in both Heating and Cooling mode. Controllers with a bi-directional output are used for maintaining a constant temperature within an enclosure surrounded by an ambient environment with a much larger temperature swing. This is commonly experienced in an outdoor environment. Laird offers a microcontroller based device with integrated temperature control for cooling and heating of thermoelectric assemblies requiring precise temperature control. The TC-XX-SR-54 has 3 programmable fan outputs, alarm output relay and alarm condition LEDs. The parameters will be programmed by Laird according to customer specifications.

Proportional Controllers use proportional regulation to maintain a constant temperature with no swing in the control temperature. This is accomplished by using a PID algorithm to determine the output value and a Pulse Width Modulation (PWM) output to handle the physical control. Proportional Controllers are often used in heating and cooling systems where the temperature must stay constant (with no change) regardless of the change in ambient temperature. Laird offers two standard programmable controllers. The PR-59 is mountable at system level and comes with software to connect to PC. Settings can be adjusted while running TEA, which is beneficial for product development.

Temperature controllers can accommodate more advanced options. Outputs are available for fan, thermoelectric module, thermistor, tachometer sensor on fan, overheating thermostat switch, alarm and LED. However, interface with Laird is required to customize temperature controller settings to meet your unique application requirements. Consult with a Laird Technologies engineer on customized solutions relating to specific design criteria. MOQ applies.


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