Model TC-24-12 Temperature Controller

APPLICATION
The TC-24-12 provides bi-polar control for on-demand heating or cooling as required to maintain a set temperature. The controller is also well suited for customers that desire a controller with on-board temperature status indicators, an over-temperature alarm, or signal test-points to aid in the setup and monitoring the sensor and potentiometer voltages.

TECHNICAL DESCRIPTION
The TC-24-12 uses pulse-width-modulation (PWM) at 1000 Hz to control the average power being applied to the thermoelectric cooler. Proportional and integral control settings can be adjusted to fine-tune the control stability. The controller consists of a microprocessor, thermistor inputs, a power output stage, and set-temperature/tuning potentiometers. Temperature status indicator LED's and test points are also included. For high-volume applications, the tuning potentiometers can be removed and set-point/tuning parameters can be preprogrammed from the factory to further reduce the controller's cost and set up time.

Two optional thermistors or thermostats can be used to detect fault conditions so that power is automatically turned off when a fault is detected. The controller can be set up to automatically restart if the fault clears itself, or it can be set for manual restart in which power to the controller must be turned off and then on again to resume temperature control. An output connection on the circuit board is also included to signal external devices of a fault condition.

The TC-24-12 operates with an input voltage range of 10.8 to 26.4 VDC. (A minimum of 10.8 VDC input is needed to operate the on-board microprocessor.) It will control output currents of up to 11.9 amps maximum. Bi-polar output is provided by an H-bridge output stage, which uses highly efficient N-channel MOSFET output devices so that no additional heat sinking is needed. Furthermore, the PWM methodology (when used properly) does not adversely affect the cooler's reliability that might otherwise happen with typical on-off/thermostatic types of controllers.

Note: The TC-24-12 comes with one MP-2379 thermistor. If you would like to purchase additional thermistors, please indicate when ordering.

SPECIFICATIONS

• Input voltage from 10.8 to 26.4 volts DC (external power supply required)
• Maximum 11.9 amps output current
• Proportional-Integral (PI) control
• Bi-directional, solid-state H-bridge operation for heating and cooling applications
• Pulse-width modulation of output at 1000 Hz
• Control temperature of –20 °C to 100 °C using MP-2379 thermistor (supplied with the controller)
• Control stability of up to ±0.3 °C (when controlling a cold plate)
• Proportional (P) bandwidth adjustment of 1.0 °C to 15.0 °C and Integral (I) rate adjustment of 0 to 2.55 repeats per minute
• Removable terminal strip for easy connection of power, cooler, and thermistors
• Test points for reading Set Temperature, P, I, and thermistor voltages
• Temperature status LED's
• Two inputs for optional, over-temperature thermistors or thermostats
• Over-temperature alarm with alarm output transistor configurable for continuous shutdown or automatic resetting of output power
• Fault detection indications through the LED's
• Operating temperature range: 0 to 60 °C
• Storage temperature range: -55 to 105 °C