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IC Temperature Controllers in SMT or THT Packages![]()
MTD415L SMT Package for ±1.5 A and MTDEVAL1 Evaluation Board for OEM TEC Drivers 21.0 mm 12.4 mm 39.6 mm 21.5 mm MTD1020T THT Package for ±2.0 A and 10 kΩ Thermistor 114.5 mm 64.0 mm MTD415TE Adapter PCB with Mounted MTD415T 27.0 mm 21.0 mm Related Items ![]() Please Wait Volume Pricing & OEM SupportThorlabs' production facilities are capable of manufacturing TEC controllers in high volumes, and we pass the savings associated with planned production on to our customers. Contact our OEM team to learn more. An OEM specialist will contact you within 24 hours or on the next business day. ![]() Click to Enlarge Upon request, large-quantities of MTD415 series drivers in SMT packages can be delivered in an IC tube. ![]() Click to Enlarge Application Example MTD415L TEC drivers are used for temperature regulation in Thorlabs' Nanosecond Pulsed Laser Systems, as shown in this cutaway view of the NPL64A. Features
Applications
Thorlabs offers several complete driver module options designed for OEM system integration. The high compliance voltage of the MTD1020T, which is offered in a through-hole technology (THT) package, allows it to deliver the maximum ±2.0 A TEC current into load resistances up to 5 Ω. The MTD415 Series, which are offered in surface-mount technology (SMT) packages and as SMT packages mounted on daughterboards, deliver TEC current up to ±1.5 A depending on the load resistance. Please see the Specs tab for typical performance plots and specifications. Each of these OEM-grade TEC drivers employs a digital control loop to regulate the current output. These PID control loops enable our TEC drivers to provide faster temperature settling times and better stability than drivers using PI control loops. True bipolar operation allows the output current to reach 0 A without "dead zones" or other nonlinearities at low TEC currents. The complete on-chip power stage and thermal control loop circuitry minimize external components while maintaining high efficiency and low output current noise of <10 mA. The output current is directly controlled to eliminate current surges to the TEC, while an adjustable TEC current limit provides protection against overdriving the cooler. Computer Control Evaluation Board All technical data are valid at 23 ± 5 °C and 45 ± 15% relative humidity (non-condensing). TEC Driver Specifications
TEC Driver Absolute Maximum Ratings
TEC Controller Package Dimensions
MTD415 Series Typical Output Characteristics![]() Click to Enlarge MTD415 Series deliver the maximum output power of 6 W into a load resistance of 2.66 Ω when operating under recommended conditions. The shaded range corresponds to load resistances less than 2.66 Ω, for which the maximum output power depends on environmental conditions. ![]() Click to Enlarge MTD415 Series deliver the maximum TEC current of 1.5 A into a load resistance of 2.66 Ω when operating under recommended conditions. The maximum output current drops for higher load resistances due to the limit of the compliance voltage. The shaded range corresponds to load resistances less than 2.66 Ω, for which the maximum output current depends on environmental conditions. MTD1020T Typical Output Characteristics![]() Click to Enlarge MTD1020T delivers the maximum output power of 20 W into a load resistance of 5 Ω, when operating under recommended conditions and actively cooled, or for ambient temperatures between -20 °C and 20 °C when convection cooled. The red curve applies to an ambient temperature of 60 °C and convection cooling. ![]() Click to Enlarge MTD1020T delivers the maximum TEC current of 2.0 A into load resistances up to 5 Ω, when operating under recommended conditions and actively cooled with 2 m/s forced air or cooling methods at least equally effective. When convection cooled, the maximum 2.0 A current can be delivered into any load resistances up to 5 Ω for ambient temperatures up to 20 °C. Other cooling methods may give intermediate results. MTDEVAL1 Evaluation Board
Click on the following links to move to the different sections in this discussion.
Pin Layout of the MTD415 Series
Typical Application Circuits for the MTD415 Series![]() Click to Enlarge Sample External Circuit for MTD415L TEC Driver ![]() Click to Enlarge Sample External Circuit for MTD415T TEC Driver
Pin Layout of the MTD1020T
![]() Click to Enlarge Sample External Circuit for MTD1020T TEC Driver ![]() Click to Enlarge The OEM Temperature Controller GUI Interface GUI and Drivers for OEM Temperature Controllers and Evaluation BoardThe download button below provides a link to the GUI and drivers that allow these TEC drivers to be controlled via a PC with a Windows® operating system. The software can be used to perform an oscillation test and can automatically calculate the optimal P, I, and D parameters for a setup using the results. For details on the oscillation test procedure and an introduction to PID circuits, see the PID Oscillation Test tab.
![]() Click to Enlarge Figure 2: Initial Settling Behavior after TEC is Enabled ![]() Figure 1: Starting Parameters for the Oscillation Test Oscillation Test to Set PID ParametersEach MTD415 and MTD1020T module incorporates a digital PID controller. The P, I, and D shares can be programmed manually or calculated automatically by the firmware by entering the results of a loop oscillation test. This test can be performed using the GUI available on the Software tab, and provides a convenient method for optimizing the PID parameters. Before running the test, the following preconditions must be met:
First, enter the PID loop settings shown in the table to the upper right. These initial settings allow the user to observe the temperature settling process, as typically no oscillations will appear when the driver is operated with these settings. Then, enable the TEC. The actual temperature, measured by the unit and recorded on the graph in the GUI, will approximate the set value. ![]() Click to Enlarge Figure 4: P Share = 5000 mA/K ![]() Click to Enlarge Figure 3: P Share = 10,000 mA/K ![]() Click to Enlarge Figure 6: P Share = 2000 mA/K ![]() Click to Enlarge Figure 5: P Share = 3000 mA/K ![]() Click to Enlarge Figure 8: P Share = 2800 mA/K ![]() Click to Enlarge Figure 7: P Share = 2600 mA/K ![]() Click to Enlarge Figure 10: P Share = 2650 mA/K ![]() Click to Enlarge Figure 9: P Share = 2700 mA/K The critical P share (critical gain) is the value at which the system starts to oscillate for a minimum of 20 cycles without a drop in amplitude as a reaction to a change in the temperature setpoint. The procedure for the oscillation loop test used to find the critical P share is described as follows: with I and D set at zero, the P share value is set high enough that the loop oscillates without damping. Then, smaller P share values are tested until the oscillations are damped. The P share is increased again by a smaller amount until the loop begins to oscillate continuously again, and then decreased to find the threshold where the oscillations become damped again. After each change in the P share value, the temperature setpoint must be changed slightly to trigger the loop with the new P share setting. The process is repeated until the minimum P share value for the loop to oscillate without damping is found; this is the critical P share value. The following example illustrates how the oscillation loop test procedure is carried out. For this case, a passive thermal load consisting of a 60 mm x 60 mm x 25 mm radiator was connected to a TEC and a temperature sensor.
Typically, the PID optimization for settling behavior is finished at this point. If required, the PID values and the cycle time can be manually fine-tuned in order to optimize the loop response to changes of the thermal load. Saving the PID Parameters for Later Use ![]() Figure 12: Final Calculated PID Parameters ![]() Figure 11: Entering the Critical Gain and Critical Period Duration Alternatively, the PID parameters can be saved to the computer running the GUI. The next time that the GUI is used to operate the TEC driver, the saved parameters can be loaded into the GUI and will automatically populate all of the fields; the user can then select whether to save these parameters to the volatile memory only (meaning that the driver will immediately use the parameters), or to save the parameters to both the volatile and non-volatile memory. Notes The optimized PID parameters are valid for a steady state that is dependent on the set temperature as well as on the ambient conditions (ambient temperature, temperature of the thermally controlled object). Any changes in the operating and/or environmental conditions may require a re-adjustment of the PID parameters. For more information on the basics of PID circuits, see the PID Tutorial tab. PID BasicsThe PID circuit is often utilized as a control loop feedback controller and is very commonly used for many forms of servo circuits. The letters making up the acronym PID correspond to Proportional (P), Integral (I), and Derivative (D), which represents the three control settings of a PID circuit. The purpose of any servo circuit is to hold the system at a predetermined value (set point) for long periods of time. The PID circuit actively controls the system so as to hold it at the set point by generating an error signal that is essentially the difference between the set point and the current value. The three controls relate to the time-dependent error signal; at its simplest, this can be thought of as follows: Proportional is dependent upon the present error, Integral is dependent upon the accumulation of past error, and Derivative is the prediction of future error. The results of each of the controls are then fed into a weighted sum, which then adjusts the output of the circuit, u(t). This output is fed into a control device, its value is fed back into the circuit, and the process is allowed to actively stabilize the circuit’s output to reach and hold at the set point value. The block diagram below illustrates very simply the action of a PID circuit. One or more of the controls can be utilized in any servo circuit depending on system demand and requirement (i.e., P, I, PI, PD, or PID). ![]() Through proper setting of the controls in a PID circuit, relatively quick response with minimal overshoot (passing the set point value) and ringing (oscillation about the set point value) can be achieved. Let’s take as an example a temperature servo, such as that for temperature stabilization of a laser diode. The PID circuit will ultimately servo the current to a Thermo Electric Cooler (TEC) (often times through control of the gate voltage on an FET). Under this example, the current is referred to as the Manipulated Variable (MV). A thermistor is used to monitor the temperature of the laser diode, and the voltage over the thermistor is used as the Process Variable (PV). The Set Point (SP) voltage is set to correspond to the desired temperature. The error signal, e(t), is then just the difference between the SP and PV. A PID controller will generate the error signal and then change the MV to reach the desired result. If, for instance, e(t) states that the laser diode is too hot, the circuit will allow more current to flow through the TEC (proportional control). Since proportional control is proportional to e(t), it may not cool the laser diode quickly enough. In that event, the circuit will further increase the amount of current through the TEC (integral control) by looking at the previous errors and adjusting the output in order to reach the desired value. As the SP is reached [e(t) approaches zero], the circuit will decrease the current through the TEC in anticipation of reaching the SP (derivative control). Please note that a PID circuit will not guarantee optimal control. Improper setting of the PID controls can cause the circuit to oscillate significantly and lead to instability in control. It is up to the user to properly adjust the PID gains to ensure proper performance. PID TheoryThe output of the PID control circuit, u(t), is given as ![]() where From here we can define the control units through their mathematical definition and discuss each in a little more detail. Proportional control is proportional to the error signal; as such, it is a direct response to the error signal generated by the circuit: ![]() Larger proportional gain results is larger changes in response to the error, and thus affects the speed at which the controller can respond to changes in the system. While a high proportional gain can cause a circuit to respond swiftly, too high a value can cause oscillations about the SP value. Too low a value and the circuit cannot efficiently respond to changes in the system. Integral control goes a step further than proportional gain, as it is proportional to not just the magnitude of the error signal but also the duration of the error. ![]() Integral control is highly effective at increasing the response time of a circuit along with eliminating the steady-state error associated with purely proportional control. In essence integral control sums over the previous error, which was not corrected, and then multiplies that error by Ki to produce the integral response. Thus, for even small sustained error, a large aggregated integral response can be realized. However, due to the fast response of integral control, high gain values can cause significant overshoot of the SP value and lead to oscillation and instability. Too low and the circuit will be significantly slower in responding to changes in the system. Derivative control attempts to reduce the overshoot and ringing potential from proportional and integral control. It determines how quickly the circuit is changing over time (by looking at the derivative of the error signal) and multiplies it by Kd to produce the derivative response. ![]() Unlike proportional and integral control, derivative control will slow the response of the circuit. In doing so, it is able to partially compensate for the overshoot as well as damp out any oscillations caused by integral and proportional control. High gain values cause the circuit to respond very slowly and can leave one susceptible to noise and high frequency oscillation (as the circuit becomes too slow to respond quickly). Too low and the circuit is prone to overshooting the SP value. However, in some cases overshooting the SP value by any significant amount must be avoided and thus a higher derivative gain (along with lower proportional gain) can be used. The chart below explains the effects of increasing the gain of any one of the parameters independently.
TuningIn general the gains of P, I, and D will need to be adjusted by the user in order to best servo the system. While there is not a static set of rules for what the values should be for any specific system, following the general procedures should help in tuning a circuit to match one’s system and environment. In general a PID circuit will typically overshoot the SP value slightly and then quickly damp out to reach the SP value. Manual tuning of the gain settings is the simplest method for setting the PID controls. However, this procedure is done actively (the PID controller turned on and properly attached to the system) and requires some amount of experience to fully integrate. To tune your PID controller manually, first the integral and derivative gains are set to zero. Increase the proportional gain until you observe oscillation in the output. Your proportional gain should then be set to roughly half this value. After the proportional gain is set, increase the integral gain until any offset is corrected for on a time scale appropriate for your system. If you increase this gain too much, you will observe significant overshoot of the SP value and instability in the circuit. Once the integral gain is set, the derivative gain can then be increased. Derivative gain will reduce overshoot and damp the system quickly to the SP value. If you increase the derivative gain too much, you will see large overshoot (due to the circuit being too slow to respond). By playing with the gain settings, you can maximize the performance of your PID circuit, resulting in a circuit that quickly responds to changes in the system and effectively damps out oscillation about the SP value.
While manual tuning can be very effective at setting a PID circuit for your specific system, it does require some amount of experience and understanding of PID circuits and response. The Ziegler-Nichols method for PID tuning offers a bit more structured guide to setting PID values. Again, you’ll want to set the integral and derivative gain to zero. Increase the proportional gain until the circuit starts to oscillate. We will call this gain level Ku. The oscillation will have a period of Pu. Gains are for various control circuits are then given below in the chart.
![]() ![]() Click to Enlarge MTD415TE TEC Driver on Daughterboard
MTD415 Series These TEC controllers deliver powers up to 6 W and a maximum TEC current of ±1.5 A. The MTD415L(E) supports the LMT84 IC temperature sensor, and the MTD415T(E) supports a 10 kΩ thermistor. Please see the Specs tab for plots showing the dependence of the output power and current on the load resistance. Pinout diagrams and typical application circuits are included in the Pin Diagrams tab. MTD1020T The MTD1020T TEC controller delivers power up to 20 W. A maximum TEC current of ±2.0 A is delivered into any load resistance up to 5 Ω when operating under recommended conditions and adequately cooled. Please see the Specs tab for plots of the dependence of the output power on load resistance and cooling conditions, as well as a plot of the delivered current on cooling conditions. The MTD1020T supports a 10 kΩ thermistor. Pin out diagrams and a typical application circuit using the MTD1020T can be found in the Pin Diagrams tab. Volume Pricing
![]() ![]() Click to Enlarge Evaluation Board with MTD415LE TEC Driver Installed
Evaluation Board For autonomous operation of the TEC driver, it is not necessary to connect the evaluation board to a computer. When power is supplied to the board, TEC and temperature sensor wires are connected to the appropriate screw terminals, and the SW1 (ENABLE ON/OFF) switch s set in the on position, the TEC driver will operate according to the settings saved to its flash memory. Compatible TEC Drivers To protect the TEC driver from potential electrical damage, ensure that power is disconnected from the evaluation board when installing the TEC driver on the MTDEVAL1. Please note that setting the SW1 (ENABLE ON/OFF) switch to the off position does not disconnect power from the sockets. Instead, SW1 is used to enable or disable the TEC driver's control of the connected TEC. The SW1 switch should be set to the off position prior to supplying power to the board. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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