TEC Controller Clamping Circuit

Abstract

The present disclosure relates to a clamping circuit for a TEC controller. The circuits and techniques described herein can use a clamping circuit to provide reverse drive compensation in applications where a thermoelectric cooler (TEC) device is to be controlled. The reverse drive compensation circuit can be used to inhibit or prevent the linear output stage of the TEC control circuit from being forced outside of its intended operating range. The clamping circuit can be implemented using a variety of circuit topologies, such as including a comparator arrangement with hysteresis. In another approach, a linear amplifier topology can provide clamping behavior, for example, by injecting or sinking current at an output node or an intermediate node to inhibit or prevent the output node or the intermediate node from being driven outside of a specified voltage range by an external source.

Description

[0001] Priority Claim

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 141,976, entitled "Linear Stage Clamping Circuit for TEC Controller", filed on January 26, 2021 by Atout et al. (Attorney Docket No. 3867.832PRV), the entire content of which is incorporated herein by reference. Field of the Invention

[0003] This document generally but without limitation relates to regulator circuit configurations and associated control techniques, and more particularly to the control of thermoelectric cooler (TEC) devices. Background Art

[0004] Thermoelectric cooler (TEC) devices can be used in a variety of applications, including heating or cooling, or both. Compared to vapor compression refrigeration, TEC devices are compact solid-state devices that do not require the use of liquids or moving parts, such as providing a high degree of ruggedness and reliability. TEC devices use the Peltier effect to drive heat transfer or flux at the interface between two different materials. To provide heating or cooling, respectively, the polarity of the current supplied to the TEC device can be used to control whether the TEC device operates in a heating mode or a cooling mode. For example, if a forward-regulated current enters the positive terminal of the TEC device, the TEC device can operate in the cooling mode. Similarly, if the current is negatively regulated and enters the negative terminal of the TEC device, the TEC device can operate in the heating mode.

[0005] The surface of the TEC device can be thermally coupled (e.g., conductively coupled) to another structure to provide heating or cooling using heat conduction. By way of illustration, the device to be heated or cooled can include a semiconductor device or a semiconductor device package. For example, the TEC device can be included as part of an active cooling or temperature regulation device for electro-optic devices such as light-emitting diodes, light-emitting diode arrays, or laser devices. Summary of the Invention

[0006] Various control circuit topologies can be used to drive a thermoelectric cooler (TEC) device, providing heating or cooling operation, or both. In one approach, the circuit can use a combination of a linear regulator circuit and a switched-mode regulator circuit to provide bidirectional current regulation for the TEC device. This combination can include an "H-bridge" configuration, where the first half of the "H" topology includes the linear output stage of a linear regulator circuit coupled to the first terminal of the two-terminal TEC element, and the other half of the "H" topology includes the switched-mode output stage of a switched-mode regulator circuit coupled to the second terminal of the two-terminal TEC device.

[0007] A hybrid approach that includes linear and switched-mode regulator circuits provides relatively high switched-mode operation efficiency at higher output levels, as well as the ability to still provide continuous regulated output using linear mode at lower output levels, especially when there is a crossover between heating and cooling states and the current polarity reverses. Another feature provided by the hybrid approach is the ability to power the control circuit using a single supply voltage (e.g., a single positive supply and a reference node, as compared to a bipolar supply with positive and negative voltage values). This can simplify the implementation of a TEC temperature regulation system, such as in the case where the TEC control circuit includes a monolithic integrated circuit.

[0008] The present inventors have recognized that, among other things, the use of a hybrid control circuit topology presents various challenges. Theoretically, but not limited to, when a TEC device has an external heat source or thermal mass applied to one of the TEC device surfaces, for example, the external heat forces the TEC device to conduct across the TEC device and create a corresponding thermal difference, and the TEC device itself generates a voltage across the TEC device terminals, which can then be applied to the control circuit. This voltage generated within the TEC device can be referred to as the Seebeck voltage. Typically, the Seebeck voltage is independent of the TEC control circuit and appears as a voltage offset that is driven back to the TEC control circuit output. When the TEC control circuit includes a linear output stage, this "back-driving" of the Seebeck voltage can drive parts of the linear output stage beyond the specified reference voltage, for example, driving the voltage at the output node of the linear stage to a potential lower than the control circuit ground or reference potential.

[0009] When the linear stage of the control circuit is back-driven in this manner by the Seebeck voltage, the feedback and regulation behavior of the control circuit is disrupted. This results in discontinuities in the control circuit behavior and the resulting non-linearity in temperature control or other temperature regulation errors. Temperature regulation errors or discontinuities occur especially when the TEC device can operate between or near heating and cooling operating modes. Such temperature regulation errors can in turn lead to other output disturbances from the system being heated or cooled by the TEC device, such as frequency drift or errors in the output of an electro-optic device thermally coupled to the TEC device.

[0010] To address such challenges, while still using a linear regulator circuit topology (or a hybrid control circuit topology including both linear and switched-mode regulator circuits), the inventors have developed circuits and techniques to provide reverse drive compensation. The reverse drive compensation circuit can be used to inhibit or prevent the linear output stage from being forced outside of its intended operating range, such as by using a clamping circuit. The clamping circuit can be implemented using a variety of circuit topologies, such as including a comparator arrangement with hysteresis. In another approach, a linear amplifier topology can provide clamping behavior, such as by injecting or sinking current at an output node or an intermediate node to inhibit or prevent the output node or the intermediate node from being driven outside of a specified voltage range by an external source, such as a Seebeck voltage from a TEC device. The use of reverse drive compensation, as shown and described in various examples herein, can include using an integrated clamping circuit, such as co-integrated (e.g., monolithically or otherwise within the same device package) with other TEC control circuit blocks, or an external drive compensation circuit can be separate from the integrated control circuit.

[0011] In one example, an apparatus or system can include or can use a thermoelectric cooler (TEC) control circuit that controls the temperature of a TEC device by differentially driving the TEC device, the TEC control circuit including: a linear regulator circuit including an output that drives a first input node of the TEC device, a switched-mode regulator circuit including an output that drives a second input node of the TEC device, a current sensing circuit for providing a signal indicative of the current provided or absorbed by the TEC device through the output of the linear regulator circuit, and a reverse drive compensation circuit including a differential amplifier having an input coupled to the first input node of the TEC device and an output for driving a clamping circuit to inhibit the first input node of the TEC device from being driven above a specified reference voltage at or near a transition between heating and cooling operating modes of the TEC device.

[0012] In one example, a device or system can include or can use a temperature control system that includes: a thermoelectric cooler (TEC) device; and a TEC control circuit including a linear regulator circuit including an output that drives a first input node of the TEC device, a switched-mode regulator circuit including an output that drives a second input node of the TEC device, a current sensing circuit for providing a signal indicative of the current provided or absorbed by the TEC device through the output of the linear regulator circuit, and a reverse drive compensation circuit including a differential amplifier having an input coupled to the first input node of the TEC device and an output for driving a clamping circuit to inhibit the first input node of the TEC device from being driven above a specified reference voltage at or near a transition between heating and cooling operating modes of the TEC device.

[0013] In one example, a system or device can be used for temperature control. For example, a temperature regulation method is used, which includes receiving an indication of a sensed temperature, generating a control signal for a thermoelectric cooler (TEC) control circuit in response to the received indication of the sensed temperature, and using the control signal to establish a voltage across the TEC device. The voltage across the TEC device is established using a linear regulator circuit including an output driving an input node of the first input of the TEC device and a switching mode regulator circuit including an output driving an input node of the second input of the TEC device. Wherein the method includes providing reverse drive compensation by driving a clamping circuit to inhibit the first input node of the TEC device from being driven beyond a specified reference voltage at or near the transition between the heating and cooling operating modes of the TEC device.

[0014] This summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive interpretation of the invention. The detailed description is included to provide further information about this patent application. Brief Description of the Drawings

[0015] In the drawings, which are not necessarily to scale, like numerals may describe like components in different views. Like numerals with different letter suffixes may represent different instances of like components. The drawings generally illustrate, by way of example and not limitation, the various embodiments discussed in this document.

[0016] Figure 1 Generally illustrated is an example including a system that includes a thermoelectric cooler (TEC) device and a TEC control circuit.

[0017] Figure 2 Generally illustrated is an example including a driver circuit topology, including a switching mode regulator circuit, a linear regulator circuit, and a reverse drive compensation circuit.

[0018] Figure 3 Generally illustrated is an illustrative example including a TEC control circuit topology, including a switching mode regulator circuit, a linear regulator circuit, and a reverse drive compensation circuit.

[0019] Figure 4A Generally illustrated is an illustrative example including a linear clamping circuit topology, such as can be used to provide reverse drive compensation.

[0020] Figure 4B Generally illustrated is an illustrative example including a comparator-triggered clamping circuit, such as can be used to provide reverse drive compensation.

[0021] Figure 5A Generally illustrated is an illustrative example of the voltage level over time at the output node (SFB) of a switching mode regulator circuit coupled to the terminals of a TEC device.

[0022] Figure 5B An illustrative example generally showing the relationship between the voltage level and time at the output node (LDR) of a linear "low dropout" voltage regulator, the node being coupled to another terminal of the TEC device and corresponding to the same Figure 5A time interval and the same TEC device.

[0023] Figure 5C An illustrative example generally showing the sensed temperature over time of a structure coupled to the TEC device, corresponding to the same Figure 5A and Figure 5B time interval and the same TEC device as in

[0024] Figure 6 A technique is generally described, such as an operating method of a TEC control circuit, such as providing reverse drive compensation. DETAILED DESCRIPTION

[0025] Apparatus and techniques are described herein to provide a control circuit including reverse drive compensation. Reverse drive compensation can be used to inhibit or prevent the output of an externally driven linear regulator circuit from exceeding its expected operating range, such as inhibiting or preventing the output of an externally driven linear regulator circuit from dropping below the control circuit ground potential or other control circuit reference potential. For example, the control circuit can be used to drive a thermoelectric cooler (TEC) device to provide temperature regulation. A temperature sensor can provide feedback to the control circuit, such as maintaining a specified temperature set point or providing a specified temperature range during operation. The TEC device can be thermally coupled to another structure, such as to provide heating or cooling, or both. The use of reverse drive compensation as shown and described herein can reduce or inhibit temperature regulator error or discontinuity in the temperature regulator output, associated with the Seebeck voltage being driven back to the output of the TEC control circuit. Otherwise, such regulator error or output discontinuity can occur at or near the transition between the heating and cooling operating modes of the TEC device.

[0026] Figure 1 An example including system 100 is generally shown, system 100 including a thermoelectric cooler (TEC) device 104 and a TEC control circuit 110. The TEC control circuit 110 can be powered by a power supply 120 (e.g., a power supply configured to generate one or more voltages for use by the TEC control circuit 110). As an example, part or all of the TEC control circuit 110 can be implemented as an integrated circuit (e.g., a monolithic integrated circuit). Using a hybrid linear and switching mode regulation topology, such as illustratively shown in Figure 2 and Figure 3 can allow the TEC control circuit 110 to operate using a single-ended power supply, such as reducing the number of pins of the associated integrated circuit package housing the TEC control circuit 110 or simplifying the power supply used as the power supply 120.

[0027] Typically, the TEC control circuit 110 may include various blocks, such as circuits for performing current sensing 112, voltage sensing 114, and associated current limiting 118 and voltage limiting 116. The TEC control circuit 110 may include a driver circuit 102, for example, providing two or more output nodes that may be electrically coupled to the TEC device 104. In this way, temperature regulation may be performed, such as regulating the temperature (e.g., heating or cooling, or selectively heating and cooling) of an object 106. A temperature sensor 108 (e.g., a solid-state sensor such as a diode, transistor, thermocouple, or resistive temperature sensing device) may be used to provide feedback.

[0028] Feedback from the temperature sensor 108 may include an analog signal indicative of temperature, which is then processed and compared with an analog signal indicative of a temperature setpoint, for example, using a feedback control scheme implementing proportional-integral-derivative (PID) compensation. In another example, such control may be performed, for example, by digitizing the signal from the temperature sensor 108 and comparing the digital representation of the sensed temperature with the representation of the setpoint. Typically, signal conditioning may be performed within the monolithic integrated circuit-based TEC control circuit 110, for example, using a signal conditioning circuit 124 and an error compensation circuit 122. Alternatively or additionally, one or more signal conditioning or error sensing may be performed external to the monolithic integrated circuit-based TEC control circuit 110. Regardless of how and where the temperature error is determined, an output may be generated, such as a control signal from the error compensation circuit 122, for controlling the driver circuit 102. In response, the driver circuit 102 may adjust the voltage applied across the TEC device 104 to provide a heating or cooling action to drive the temperature of the object 106 towards a predefined setpoint or limit the temperature of the object 106 within a predefined range.

[0029] Figure 2 An example including the topology of the driver circuit 202 is generally illustrated, including a switching mode regulator circuit 228, a linear regulator circuit 226, and a reverse drive compensation circuit 230. As described above, various regulator circuit topologies may be used to drive a load 204. In Figure 2In the example, the linear regulator circuit 226 can provide an output stage that includes a half of the "H-bridge" topology, and the switched-mode regulator circuit 228 can form the other half of the "H-bridge" topology, with the load 204 connected between the two regulator circuits 226 and 228. In an illustrative example of the TEC control circuit, the load 204 can be a TEC device. The output node 270 of the linear regulator circuit can be referred to as "LDR" (e.g., low dropout regulator output) and can be connected to the first terminal of the load 204, and the output node 280 (e.g., switched-mode output feedback, "SFB") can be connected to the second terminal of the load 204. In the example of controlling a TEC device, the LDR node can be connected to the positive pole of the TEC device, and the SFB node can be connected to the negative pole of the TEC device.

[0030] Both the linear regulator circuit 226 and the switched-mode regulator circuit 228 can be powered by a single positive power supply node PVIN, although the layout and regulation of the PVIN node can be different for each regulator circuit, for example, to establish different power domains from the perspective of noise or isolation. Similarly, the linear regulator circuit 226 and the switched-mode regulator circuit can be connected to a common return or reference node 240A, which can be referred to as "ground", even though such a reference node does not actually need to be at ground potential or even zero volts. As in the example of PVIN, the reference node 240A does not need to be shared in common between the switched-mode regulator circuit 228 and the linear regulator circuit 226, and each of the regulator circuits 226 and 228 can refer to a separate representation of the reference node 240A to create a separate return path or "ground domain".

[0031] As discussed elsewhere herein, the driver circuit 202 can include or can be coupled to a reverse drive compensation circuit 230, which is powered, for example, by the power supply node PVIN or a power supply node derived therefrom, and includes an output connected to the output node 270 of the linear regulator circuit 226. The reverse drive compensation circuit can also be coupled to a reference 240B, which is, for example, at the same electrical potential as the reference node 240A. For example, as Figure 3 shown, the linear regulator circuit 226 and the reverse drive compensation circuit 230 can share a common linear regulator circuit "territory" designated as the node "PGNDL" 340D, which is used by the linear regulator circuit 226 block. Return reference Figure 2, the reverse drive compensation circuit 230 can be used to clamp the voltage at the clamp node 270, for example, by suppressing or prohibiting the node 270 from reaching a potential lower than the reference node 240B (or reference node 240A). This clamping can be achieved by injecting current into the LDR node, or directly using a clamping circuit, or using a signal from the clamping circuit to modulate the output transistor in the output stage of the linear regulator circuit 226. The reverse drive compensation circuit 230 can be co-integrated with other parts of the driver circuit 202 or placed separately, for example, separately from the integrated circuit that houses the driver circuit 202.

[0032] Figure 3 An illustrative example of a topology including a TEC control circuit 310 is generally shown, including a switch-mode regulator circuit 328, a linear regulator circuit 326, and a reverse drive compensation circuit 330. Similar to Figure 2 the example of Figure 3 A more detailed illustrative but non-limiting example of an H-bridge topology is shown, where the H-bridge includes output transistors 342 and 344 included as part of the linear regulator output stage 327, and transistors 346 and 348 included as part of the switch-mode regulator output stage 329.

[0033] The switch-mode regulator circuit 328 can include an oscillator and comparator circuit 354 to form a pulse-width modulation (PWM) output to a PWM driver circuit, and the output stage 329 can be used to drive a switch node SW, "L", coupled to an inductor, such as an inductor located outside the integrated circuit that houses a part or all of the rest of the TEC control circuit 310. Figure 3 The configuration shown in Figure 3 is a buck configuration, but such an example is illustrative, and other switch-mode regulator topologies can be used. In

[0034] As mentioned elsewhere, different power and ground "domains" can be used for signal isolation, for example, to prevent shot noise associated with the switch-mode regulator circuit 328 from causing noise in the linear regulator circuit 326 output or feedback loop. For example, a node labeled PVIN can be powered by a shared external power supply connected to the node VIN, such as a separate pin of the integrated circuit that houses the TEC control circuit 310 (and attached to a corresponding decoupling or filtering capacitor). Similarly, different reference nodes can be connected separately, as shown by nodes 340A, 340B, 340C, and 340D.

[0035] Typically, the linear regulator circuit 326 includes an output stage 327 driven by a linear amplifier. The error or control signal provided to the linear amplifier 352 may be generated by a temperature control circuit 350, for example, using a monitoring signal indicative of the output voltage of the linear regulator circuit 326 at node 270B, corresponding to the voltage value (LDR) at node 270A, and an indication of the sense current 356 supplied or absorbed from the TEC device 304. As mentioned elsewhere herein, the linear regulator circuit 326 may be used in a relatively low output range, for example, to assist in continuously supplying current to the TEC device 304 or, correspondingly, absorbing current from the TEC device 304, in coordination with the control of the switched-mode regulator circuit 328, to maintain a specified voltage across the TEC device 304. In a relatively high output range, the upper PMOS transistor 342 or the lower NMOS transistor 344 may be fully biased, and the switched-mode regulator circuit 328 may be used to provide a specified voltage at node 280SFB relative to the LDR node 270A.

[0036] As mentioned elsewhere herein, the TEC device 304 may apply a voltage across nodes 270A and 280 (between the LDR and SFB nodes), causing node 270A of the linear regulator circuit output stage 327 to be lower than the reference potential established at node 340D. This "reverse drive" of the TEC device 304 may cause the linear regulator output stage 327 to malfunction, for example, generating an incorrect current sense signal at node 356 or biasing the LDR node. As further discussed with respect to Figure 5A 、 Figure 5B and Figure 5C such a breakdown can lead to undesirable errors in temperature control, such as a temperature offset of the TEC device 304. In response to such behavior, the present inventors have included a reverse drive compensation circuit 330. In the example of Figure 3 , the reverse drive compensation circuit 330 is shown connected between the PVIN node and the LDR node. As described above, the reverse drive compensation circuit 330 is typically also connected to a reference node (e.g., at the same potential as nodes 340D, PGNDL). The reverse drive compensation circuit 330 may include a clamping circuit to limit the voltage of the LDR node within a desired range.

[0037] For example, if during a transition from a warmer environment to a colder environment, the TEC device 304 applies a Seebeck voltage that drives the LDR negative with respect to the reference node 340D, PGNDL (e.g., the voltage drop across the LDR and SFB results in a node voltage of the LDR that is lower than the potential of PGNDL), the reverse drive compensation circuit 330 can inject current into the LDR node to maintain the LDR at a voltage level equal to or higher than the level of the reference node 340D (e.g., clamp the LDR to prevent it from going below the ground potential represented by the node PGNDL). Such an example is illustrative, and the clamping action need not be limited to driving the LDR to maintain a voltage level higher than the potential of the node 340D of PGNDL.

[0038] Illustrative examples of clamping circuits that can be used to provide reverse drive compensation are shown in Figure 4A and Figure 4B shown. Figure 4A and Figure 4B Examples of show arrangements where a linear differential amplifier as shown in Figure 4A or a comparator-based method as shown in Figure 4B are used to drive an NMOS transistor to force the LDR node. Alternatively, referring back to Figure 3 , the transistors in the output stage 327 can be driven, or the replica devices (e.g., transistors 342’ or 344’) or bias nodes can be controlled by a linear clamping amplifier or a clamping comparator to achieve results similar to directly driving the LDR node from PVIN or the ground node through an NMOS. If the linear clamping amplifier or the clamping comparator completely bypasses the replica devices (342' or 344'), an error in the current sensing value may occur because the clamping circuit can provide or absorb current outside the feedback loop that drives the replica devices (342' or 344'). In contrast, using the output stage 327 to control the clamping of the LDR node, for example, driving a bias node therein with a clamping circuit, for example, can allow current sensing to remain operational during clamping, for example, allowing the sense current 356 to accurately depict the current of the TEC device 304 even when the LDR node is clamped by the reverse drive compensation circuit 330.

[0039] Figure 4A Generally shows an illustrative example including a linear clamping circuit topology 430A, for example, which can be used to provide reverse drive compensation. In the example of Figure 4A , the differential amplifier circuit U2 can be powered by the node VCC and the reference node 440 (e.g., as shown in Figure 3Powered by a grounding node such as PGNDL as shown. The differential amplifier circuit U2 can compare the voltage value of the LDR node with the voltage value of the reference node 440, and can provide an output proportional to the difference, such as driving a clamping transistor M2 (e.g., an NMOS device), so that this current can be injected from the PVIN node into the LDR node to prevent the LDR node from being forced below the potential of the reference (e.g., ground) node 440.

[0040] Figure 4B An illustrative example including a comparator-triggered clamping circuit 430B is generally shown, which can be used, for example, to provide reverse drive compensation. In Figure 4B the example, the comparator-triggered clamping circuit 430B can use a comparator circuit U1 to compare the threshold established by the node CONTROL with the value established by a feedback network including C1, R2, and R3. As an illustrative example, CONTROL can be set to a ground reference potential corresponding to an analog ground node (e.g., PGNDL), serving as a reference for the linear output LDR. The feedback network provides hysteresis behavior, so that the comparator U1 does not repeatedly switch between states at or near the trigger threshold. When triggered, the comparator circuit U1 can drive an NMOS device to clamp the LDR node to the potential of the reference node 440. Once triggered, the clamping circuit 430B can be reset, for example, by interrupting or forcing the output node to a value higher than the ground reference potential, or using other techniques, such as a reset circuit in the comparator circuit U1 or the feedback network. This reset behavior can prevent the comparator-triggered clamping circuit 430B from being locked in the triggered (e.g., clamped) state.

[0041] In Figure 3 、 Figure 4A and Figure 4B the example, the transistor device is shown as a field effect transistor (FET) device, but the use of such a device is illustrative and other transistor technologies (e.g., bipolar devices) can be used. Similarly, if a transistor of one conduction type is shown, the opposite conduction type can be used and corresponding modifications can be made to the power supply circuit or the polarities of the corresponding control circuits and signals to achieve the circuit implementation (e.g., the "dual" of the example shown in Figure 4A and Figure 4B ).

[0042] Figure 5A An illustrative example 576 of the voltage level at the output node (SFB) of a switched-mode regulator circuit coupled to the terminals of a TEC device over time is generally illustrated, and Figure 5B an illustrative example 586 of the voltage level at the linear "low dropout" regulator output node (LDR) coupled to the other terminal of the TEC device over time is generally illustrated, and corresponds to Figure 5AThe same time intervals and the same TEC device. Figure 5C Generally illustrates an illustrative example 596 of sensed temperature versus time of a structure coupled to a TEC device, corresponding to the same time intervals and the same TEC device as in Figure 5A and Figure 5B The voltage waveforms of Examples 576 and 586 result in the sensed temperature of Figure 5C . In the sensed temperature waveform of Example 596 of Figure 5C there is an offset 592. This offset is different from the otherwise nearly linear temperature progression of waveform 596. This offset 592 occurs because the control of the TEC device is interrupted when the LDR voltage of Example 586 drops below the zero volt reference potential, as shown in region 582 of Example 586 of Figure 5B . As discussed elsewhere herein, region 582 may be associated with a Seebeck voltage that is driven in reverse into the LDR node. The use of the reverse drive compensation scheme shown and described above can be used to clamp the LDR voltage in Example 586 to provide a clamp level 584. In this way, the offset 592 shown in Example 596 can be suppressed or inhibited, for example, linearizing the sensed temperature (e.g., the regulated temperature response), as shown at 594. By way of illustration, if the TEC device is thermally coupled to an optoelectronic device, such as a laser, the thermal offset 592 can cause an unwanted wavelength (or frequency) deviation at the output of the laser. By eliminating or reducing the magnitude of the offset 592, the corresponding wavelength (or frequency) deviation can be reduced.

[0043] Figure 6 Generally illustrates a technique, such as an operating method 600 of a TEC control circuit, for example, providing reverse drive compensation. Method 600 can include, at 605, receiving an indication of sensed temperature. The indication can be an analog signal such as obtained using the sensors described above. The sensed temperature can be provided from a sensor coupled to a structure that is heated or cooled by the TEC device (e.g., the temperature need not represent the temperature of the TEC device itself). At 610, in response to an analog or digital representation of the sensed temperature, a control signal can be generated for the TEC control circuit. Such a control signal can include one or more error signals that represent the difference between the sensed temperature and a temperature setpoint, or an indication of whether heating or cooling operation is required, for example, in response to detecting that the temperature is outside a specified range or exceeds a specified threshold.

[0044] At 615, for example in response to a control signal, a voltage can be established across the TEC device. As an illustrative example, the voltage can depend on the degree of deviation between the sensed temperature and the temperature set point, or the voltage can be a specified value established based on the nominal operating voltage of the TEC device to provide a fixed heating or cooling heat flux. At 615, the voltage established across the TEC device can include transitioning the TEC device from a cooling mode to a heating mode, or vice versa. At 620, reverse drive compensation can be provided, such as using a reverse drive compensation circuit to provide clamping as shown and described elsewhere herein, for example to prevent at least a first input node of a TEC device (e.g., the positive node connected to the linear regulator output) from being driven beyond a specified reference voltage.

[0045] Various notes

[0046] Each of the above non-limiting aspects can exist independently or can be combined with one or more of the other aspects or other topics described in this document in various permutations or combinations. The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings illustrate, by way of example, specific embodiments in which the invention can be practiced. These embodiments are also collectively referred to as "examples". Such examples can include elements other than those shown or described. However, the inventors also contemplate examples that provide only those elements shown or described. Additionally, the inventors also contemplate examples that use any combination or permutation (or one or more aspects thereof) of those elements shown or described, or with respect to a particular example (or one or more aspects thereof), or with respect to other examples shown or described herein (or one or more aspects thereof).

[0047] If there is any inconsistency in the usage between this document and any document incorporated by reference, the usage in this document shall prevail.

[0048] In this document, the terms "a" or "some" are common in patent documents and are used to include one or more, independent of any other instances or uses of "at least one" or "one or more". In this document, unless otherwise specified, the term "or" is used to refer to a non-exclusive or, e.g., "A or B" includes "A but not B", "B but not A", and "A and B". In this document, the terms "comprising" and "wherein" are used as simple equivalents of the corresponding terms "including" and "wherein". Additionally, in the following claims, the terms "comprising" and "containing" are open-ended, i.e., a system, apparatus, article of manufacture, composition, formulation, or process that comprises elements other than those listed after such terms is still considered to fall within the scope of that claim. Further, in the appended claims, the terms "first", "second", "third", etc. are used only as labels and do not impose a numerical requirement on their objects.

[0049] The method examples described herein can be at least partially machine or computer-implemented. Some examples can include a computer-readable medium or a machine-readable medium encoded with instructions that are operable to configure an electronic device to perform the methods as described in the above examples. The implementation of such methods can include code, such as microcode, assembly language code, high-level language code, etc. Such code can include computer-readable instructions for performing various methods. The code can form part of a computer program product. For example, such instructions can be read and executed by one or more processors to implement the execution of operations including the methods. The instructions are in any suitable form, such as but not limited to source code, compiled code, interpreted code, executable code, static code, dynamic code, etc.

[0050] In addition, in one example, the code can be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of such tangible computer-readable media can include but are not limited to hard disks, removable disks, removable optical discs (e.g., optical discs and digital video discs), magnetic tapes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0051] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used, such as by those of ordinary skill in the art after reading the above description. The abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above detailed description, various features can be combined together to simplify the disclosure. This should not be construed as intending that the disclosed features not claimed are essential for any claim. Instead, the subject matter of the invention may lie in less than all of the features of a particular disclosed embodiment. Accordingly, the following claims are hereby incorporated into the detailed description as examples or embodiments, each claim standing on its own as a separate embodiment, and it is contemplated that these embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims and the full scope of equivalents to which those claims are entitled.

Claims

1. A thermoelectric cooler (TEC) control circuit that controls the temperature of a TEC device by differentially driving the TEC device, the TEC control circuit comprising: A linear regulator circuit including an output that drives a first input node of the TEC device; A switched-mode regulator circuit including an output that drives a second input node of the TEC device; A current sensing circuit for providing a signal indicative of the current supplied or absorbed by the TEC device through the output of the linear regulator circuit; And A reverse drive compensation circuit including a differential amplifier having an input coupled to the first input node of the TEC device and an output for driving a clamping circuit to inhibit the first input node of the TEC device from being driven above a specified reference voltage at or near the transition between the heating and cooling operating modes of the TEC device.

2. The TEC control circuit of claim 1, wherein the differential amplifier is for driving the clamping circuit to establish a shunt current from the first input node of the TEC device that is proportional to the supply current provided by the linear regulator circuit to inhibit the first input node of the TEC from being driven above the specified reference voltage.

3. The TEC control circuit of claim 1, wherein the specified reference voltage corresponds to a common node potential, and wherein the differential amplifier output is arranged to drive the clamping circuit to inhibit the first input node of the TEC device from being driven below the common node potential.

4. The TEC control circuit of claim 1, wherein the linear regulator circuit includes an output stage that includes transistors of complementary conductive types, the output stage including a first output stage transistor connected to a positive power supply node and a second output stage transistor connected to a node corresponding to the specified reference voltage; and wherein the differential amplifier is arranged to drive the clamping circuit to inhibit the first output stage transistor from driving the first input node of the TEC device below the potential of the node corresponding to the specified reference voltage.

5. The TEC control circuit of claim 1, wherein the differential amplifier includes a comparator circuit; and wherein the comparator circuit is arranged to drive the clamping circuit to inhibit the first input node of the TEC from being driven above the specified reference voltage in response to the comparator circuit being triggered.

6. The TEC control circuit of claim 1, wherein the reverse drive compensation circuit is arranged to drive the clamping circuit to inhibit the first input node of the TEC device from being driven above the specified reference voltage at or near the transition between the heating and cooling operating modes of the TEC device without the need to inhibit or disable the current sensing circuit.

7. The TEC control circuit of claim 1, further comprising a clamping circuit.

8. The TEC control circuit of claim 7, wherein the reverse drive compensation circuit and the current sensing circuit are monolithically integrated with the linear regulator circuit.

9. The TEC control circuit of claim 8, wherein the clamping circuit is also integrally integrated with the reverse drive compensation circuit and the current sensing circuit.

10. The TEC control circuit of claim 1, comprising a temperature control circuit configured to control the linear regulator circuit and the switch mode regulator circuit to establish a specified voltage across the TEC device using the first input node of the TEC device and the second input node of the TEC device.

11. The TEC control circuit of claim 10, comprising a temperature sensor electrically coupled to the temperature control circuit; and wherein the temperature control circuit is configured to adjust the specified voltage in response to a signal indicative of the temperature provided by the temperature sensor and a temperature set point value.

12. The TEC control circuit of claim 11, wherein the temperature sensor indicates the temperature of the optoelectronic device.

13. The TEC control circuit of claim 12, wherein the optoelectronic device comprises a laser.

14. The TEC control circuit of claim 11, wherein the temperature control circuit comprises at least one of a digital feedback topology or an analog proportional integral derivative (PID) feedback topology.

15. A temperature control system, comprising: A thermoelectric cooler (TEC) device; and A TEC control circuit, comprising: A linear regulator circuit comprising an output driving a first input node of the TEC device; A switch mode regulator circuit comprising an output driving a second input node of the TEC device; A current sensing circuit for providing a signal indicative of the current supplied or absorbed by the TEC device through the output of the linear regulator circuit; and A reverse drive compensation circuit comprising a differential amplifier having an input coupled to the first input node of the TEC device and an output for driving a clamping circuit to inhibit the first input node of the TEC device from being driven above a specified reference voltage at or near the transition between the heating and cooling operating modes of the TEC device.

16. The system of claim 15, wherein the TEC control circuit comprises a temperature control circuit configured to control the linear regulator circuit and the switch mode regulator circuit to establish a specified voltage across the TEC device using the first input node of the TEC device and the second input node of the TEC device.

17. The system of claim 16, comprising a temperature sensor electrically coupled to the temperature control circuit; and wherein the temperature control circuit is configured to adjust the specified voltage in response to a signal indicative of the temperature provided by the temperature sensor and a temperature set point value.

18. The system of claim 15, further comprising an optoelectronic device mechanically coupled to the TEC device, the TEC control circuit being configured to regulate the temperature of the optoelectronic device at least in part by using heat transfer driven to or from the optoelectronic device by the TEC device.

19. A temperature regulation method, comprising: Receiving an indication of a sensed temperature; Generate a control signal for a thermoelectric cooler (TEC) control circuit in response to an indication of a sensed temperature; and Establish a voltage across the TEC device using the control signal, and establish the voltage across the TEC device using a linear regulator circuit including an output driving a first input node of the TEC device and a switched-mode regulator circuit including an output driving a second input node of the TEC device; Wherein the method includes providing reverse drive compensation by driving a clamping circuit to inhibit the first input node of the TEC device from being driven above a specified reference voltage at or near a transition between heating and cooling operating modes of the TEC device.

20. The method of claim 19, including regulating the temperature of the optoelectronic device at least in part by using heat transfer from or to the optoelectronic device driven by the TEC device.

Images