Temperature controller circuit, apparatus and method

Abstract

An improved temperature controller circuit is provided, the temperature controller circuit including two or more sensor stages electrically connected in parallel, each sensor stage including a sensor element and a sensor element controller.

Description

[Technical field]

[0001] There is an increasing demand for temperature sensors that utilize temperature controller circuits in the sensor element, which require cost-efficient production, e.g. reducing material and energy consumption. One essential requirement for high reliability is the proper soldering (mechanically, climatically, thermo-mechanically, chemically, thermally, optically, etc.) of the wires with defined geometric dimensions (soldering position relative to the chip, positioning, etc.), usually using solder paste, solder balls or solder bars. Currently, the state of the art techniques for soldering wire-contact electronic components are immersion soldering, overflow soldering and solder paste sintering. [Background technology]

[0002] However, these techniques subject both the wires and the chips to high temperatures, leading to heavy flux deposition at the chip level. In addition, the need to recover unused solder material in the dip soldering and overflow soldering processes leads to the accumulation of foreign matter. Also, conventional techniques cannot be adapted to mass production of smaller chip dimensions.

[0003] An example of an NTC thermistor element is known from DE 10 2005 017 816 A1.

[0004] A conventional series connection of sensor elements is used to combine the sensor elements with a temperature controller circuit. However, a simple series connection has the disadvantage that the scrap rate of the series connection is high due to interruption of the chip assembly. However, a conventional parallel connection has a high power supply requirement.

[0005] Furthermore, the high voltages required in conventional circuits may increase space consumption and dimensions if a Faraday cage is required for high voltage protection. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] DE 102005017816 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above, therefore, an improved temperature controller circuit is desired. [Means for solving the problem]

[0008] To that end, according to the independent claims a temperature controller circuit is provided. The dependent claims provide preferred embodiments of a temperature sensor device and a method for detecting temperature.

[0009] The temperature controller circuit includes an evaluation circuit and two or more sensor stages, each of which includes a sensor element and a sensor element controller, the sensor stages being electrically connected in parallel.

[0010] By connecting the individual sensor stages in parallel with each other, the operating voltage can be reduced since the full operating voltage is applied to each stage, and therefore a Faraday cage is not required.

[0011] Furthermore, providing a sensor element controller for each sensor stage ensures that an optimal power or load is applied to each sensor element, in contrast to known temperature controller circuits which are configured in parallel and in the absence of a specific sensor element controller may result in different loading of individual sensor elements due to differences in ohmic resistance of the individual sensor elements of a sensor stage.

[0012] Thus, by virtue of the above arrangement, particularly the parallel connection of the sensor stages and the provision of the sensor element controller, a temperature controller circuit can be provided to provide scrap reduction of 2% to 10% or more in the event of an interruption due to mechanical motion. Furthermore, improper assembly of the final product can be detected before the start of the final assembly process. Furthermore, costs for manufacturing equipment, maintenance and self-calibration of the circuitry, and power supplies can be reduced. Furthermore, space consumption is reduced. Furthermore, weak solder joints can be detected during processing.

[0013] Additionally, the individual temperatures of the individual sensor elements can be read and the corresponding data recorded. Additionally, the individual resistances of the individual sensor elements can be evaluated.

[0014] The manufacturing of chips such as NTC, PTC or any passive components may require a heating process (soldering, coating, aging, etc.). This heating, also called Joule heating, can be generated by applying power (P=V*I=I^2*R) to the sensor element. The temperature of the element is a function of the applied power and the dissipation factor associated with the thermal conduction of the sensor element to its environment, and is proportional to the energy or power required to raise the temperature of the chip body by one Kelvin, so the desired temperature can be obtained by controlling the power that can be applied with a temperature controller circuit. This circuit also allows the temperature of the chip to be detected by measuring the resistance during the heating process.

[0015] Furthermore, the sensor element of each stage may be a sensor element having a temperature dependent resistance, specifically, the sensor element of each stage may be selected from a thermistor, an NTC element (NTC=negative temperature coefficient), a PTC (PTC=positive temperature coefficient).

[0016] Thus, a passive element can be used for the sensor element.

[0017] The sensor element controller of each stage may include an active element, which may be selected from a voltage controlled element, a MOSFET (MOSFET = Metal Oxide Semiconductor Field Effect Transistor), a current controlled element, a BJT (BJT = Bipolar Junction Transistor), and a controlled current source.

[0018] In each sensor stage, the sensor element and the sensor element controller can be electrically connected in series or in parallel.

[0019] In contrast to conventional temperature controller circuits that include parallel connected sensor elements, which result in unbalanced loading of the various sensor elements and increased chances of failure, the above-described sensor elements allow for balanced loading of each sensor element since the loads are individually controlled by the sensor element controller, thus reducing the chances of failure and increasing the useful life of the sensor elements.

[0020] The evaluation circuit can be selected from a microcontroller, an ASIC (ASIC = Application Specific Integrated Circuit) or an FPGA (FPGA = Field Programmable Gate Array).

[0021] The temperature-dependent parameters of the sensor elements can be derived from control parameters of the individual sensor element controllers, such as voltage or current. The temperature can be derived from the corresponding temperature-dependent parameters. This data processing can be performed by an evaluation circuit. Additional parameters can be stored in the evaluation circuit, such as parameters of a fitting curve or a look-up table, so that the actual temperature can be calculated based on the temperature-dependent parameters. In particular, the temperature-dependent parameter of the sensor element can be the resistance of the sensor element.

[0022] Each sensor stage may also include an operational amplifier that is used to drive the sensor element controller of each sensor stage such that the voltage and / or current applied to the sensor element of the corresponding sensor stage is at optimal operating conditions.

[0023] To this end, the corresponding operational amplifier may have an input, an inverting input, and an output. The operational amplifier may have its output connected to the sensor element controller of the corresponding stage. The inverting input may also be connected to the output of the operational amplifier. The non-inverting input of the operational amplifier may be connected to an additional circuit element block of the temperature controller circuit. The additional circuit element block may be a voltage converter electrically connected between the evaluation circuit and the corresponding operational amplifier. The voltage converter of the temperature controller circuit may include two operational amplifiers that may be electrically connected in series.

[0024] A voltage converter can be used with the control signal from the evaluation circuit, which can be used to convert the control signal, such as a PWM signal (PWM = Pulse Width Modulation), into an analog voltage and / or amplify it.

[0025] Specifically, the voltage converter may include a series inductance element and a shunt capacitance element that function as a low pass filter.

[0026] Each sensor stage may further include an output operational amplifier, which may be electrically connected between the sensor stage and an input port of the evaluation circuit. The output operational amplifier may also include a non-inverting input, an inverting input, and an output. The output of the output operational amplifier is electrically coupled to the evaluation circuit. The inverting input is electrically connected to the output of the output operational amplifier. The non-inverting input of the output operational amplifier is coupled to the sensor stage.

[0027] Additionally, each sensor stage may include a voltage divider.

[0028] The voltage divider may include, for example, two resistive elements electrically connected in series between the sensor element of the corresponding stage and ground. At a node between the two resistive elements of the voltage divider, a corresponding non-inverting input of the output operational amplifier is electrically coupled to the voltage divider.

[0029] The temperature controller circuit may further include an ADC (Analog-to-Digital Converter) electrically connected to the input of the evaluation circuit.

[0030] The temperature controller circuit can convert, by means of an ADC, analog signals such as the voltages or currents obtained from the stages into digital signals that can be processed by the digital circuitry of the evaluation circuit.

[0031] The ADC may have an input for each sensor stage.

[0032] The temperature controller circuit may further include a voltage divider electrically connected to the ADC. Specifically, the voltage divider connected to the ADC may include two resistive elements electrically connected in series between a voltage supply connection of the temperature controller circuit and ground. The ADC may also be coupled to the voltage divider via an operational amplifier, specifically to a central node between the two resistive elements of the voltage divider. The operational amplifier connected to the voltage divider connected to the voltage supply port may include an output, a non-inverting input, and an inverting input, the inverting input being electrically connected to the output and the non-inverting input of the operational amplifier being connected to a node between the two resistive elements of the voltage divider. As mentioned above, the temperature controller circuit may further include a voltage converter, the voltage converter being electrically disposed between the output of the evaluation circuit and the respective input of the sensor stage. The voltage converter may include two operational amplifiers electrically connected in series between the evaluation circuit and an operational amplifier driving the sensor element controller of the stage. Specifically, a first operational amplifier is electrically coupled to the evaluation circuit via its non-inverting input and an inverting input is electrically connected to the output of the first operational amplifier of the voltage converter. Furthermore, the output of a first operational amplifier of the voltage converter is connected to a non-inverting input of a second operational amplifier of the voltage converter, the inverting input of the second operational amplifier being coupled, for example via a resistive element, to the output of the second operational amplifier of the voltage converter, which output is coupled to the non-inverting input of a corresponding input operational amplifier that drives the sensor element controller.

[0033] The number of sensor stages can be 2 or more. In particular, the number of sensor stages can be 10 or more, 100 or more, or 1000 or more. A preferred number of parallel sensor stages can be 40, 100, or 500.

[0034] When the circuitry of the sensor stages is realized as an integrated circuit in an IC chip, the number of sensor stages becomes virtually unlimited, even exceeding 10,000, which makes the temperature measurement of the sensor element extremely accurate.

[0035] The temperature controller circuit may be implemented as a circuit within the temperature sensor device such that the temperature sensor device includes the temperature controller circuit described above.

[0036] In a temperature sensor arrangement, the sensor stage circuitry or the evaluation circuitry may be provided within the chip containing the sensor element.

[0037] In particular, the chip may include the active circuit elements of the sensor element controller of the stage, and the active circuitry of any ADC and evaluation circuitry.

[0038] The output port of the evaluation circuit can be provided with a display so that an environmental parameter such as the resistance of the sensor element or the temperature corresponding to said resistance can be displayed.

[0039] The temperature controller circuit may further include a low pass filter including a series inductance element and a shunt capacitance element.

[0040] The temperature controller circuit may further include a display that continuously monitors the presence of a faulty sensor stage.

[0041] In this context, during operation the sensor stage or its sensor elements may fail, since heating may be involved during operation and heating may accelerate degradation of materials.

[0042] The sensor device may further include thermal insulation of one or more sensor elements. The thermal insulation may be implemented as wires to the sensor elements having a thermal conductivity lower than that of copper or aluminum. The reduced thermal conductivity reduces the power required to maintain a desired temperature level.

[0043] The above-described configuration, and in particular the method of detecting temperature using two or more parallel sensor stages, includes distributing temperature detection across two or more sensor stages while controlling the power or load of each sensor stage.

[0044] The voltage converter controlling the input operational amplifier which controls the sensor element controller may be a PWM analog voltage converter (PWM=Pulse Width Modulation).

[0045] The sensor element controller may be electrically connected between the sensor element and ground, and an additional shunt element may be electrically connected between the sensor element controller and ground, the corresponding shunt being used to measure the current through the sensor element by the sensor element controller.

[0046] A voltage divider can be used to step down a corresponding voltage applied to the voltage divider by a specific ratio, which is determined by the ratio of the resistance values ​​of two of the resistive elements connected in series.

[0047] The output operational amplifier can act as a voltage buffer that can be used to convert a high impedance voltage signal to a low impedance voltage signal to protect a downstream ADC and / or microcontroller from overvoltages.

[0048] An ADC can be used to read all analog signals and convert them into digital signals that are read by an evaluation circuit.

[0049] A voltage converter (e.g. in the form of a PWM analog voltage converter) may convert the PWM signal provided by the evaluation circuit into an analog signal which may then be applied to the gate connection of a MOSFET as part of the sensor element controller, with an additional voltage buffer realised for example by an input operational amplifier.

[0050] The evaluation circuit can be used to perform numerical calculations and transmit the corresponding process data to a display. The evaluation circuit can also be used to control the current through the sensing element by controlling the duty cycle of the PWM signal applied to the voltage converter.

[0051] A measured environmental parameter, such as temperature dependent resistance, can be converted to temperature using the Steinhart and Hart equation.

[0052] A method of detecting temperature may include determining and / or measuring the current through one, several, or all of the sensor elements.

[0053] The principle of operation and the core circuit elements providing the corresponding functionality are illustrated in the accompanying schematic diagram. [Brief description of the drawings]

[0054] [Figure 1] FIG. 1 shows an overview of the circuit blocks of the temperature controller circuit. [Diagram 2] FIG. 2 shows a perspective view of a chip between two wires in which a sensor element can be realized. [Diagram 3] FIG. 3 shows three sensor stages electrically connected in parallel with each other. [Figure 4] FIG. 4 shows a further possibility for realizing three sensor stages. [Diagram 5] FIG. 5 shows a third possibility for realizing three sensor stages. [Figure 6] FIG. 6 shows an exemplary variation of the temperature controller circuit for the sensor stage shown in FIG. [Figure 6A] FIG. 6A shows an exemplary variation of a temperature controller circuit for the sensor stage shown in FIG. [Figure 6B] FIG. 6B shows an exemplary variation of the temperature controller circuit for the sensor stage shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] FIG. 1 shows the central functional blocks of the temperature controller circuit TCC. The temperature controller circuit TCC includes an evaluation circuit EVC and three sensor stages SST, which are not limited to three sensor stages as indicated by the three dots. The number of sensor stages of the temperature controller circuit is essentially limited only by the area or volume available for establishing the sensor stages. Each sensor stage is electrically coupled in parallel to each of the other sensor stages. Each sensor stage SST includes a sensor element SE and a sensor element controller SEC. The sensor element SE can be realized as a circuit element with a temperature-dependent behavior, such as a temperature-dependent resistance, for example a thermistor THE.

[0056] 2 shows the arrangement of tips CH at the two ends of a wire WI, which are soldered to the wire WI with a fixed solder length SL.

[0057] The chip CH may essentially include only a sensor element SE, such as a thermistor, but the chip CH may also include additional circuit elements of the temperature controller circuit, or all of the circuit components of the temperature controller circuit.

[0058] Power to operate the temperature controller circuitry can be applied by wires WI, or the wires can be used to apply a corresponding voltage or current to a sensor element realized within the chip CH.

[0059] By controlling the sensor element by the sensor element controller, the load or power consumption on the chip CH is controlled and does not exceed critical values ​​that may jeopardize the mechanical stability of the solder connections, thereby improving reliability and service life.

[0060] Fig. 3 shows a possible realization of three parallel sensor stages SST, each including a resistive element as a sensor element SE. Furthermore, each stage includes a sensor element controller SEC. The sensor element controller SEC may be realized as an active switch, such as a field effect transistor, such as a MOSFET, as shown on the left side of Fig. 3. The MOSFET includes a drain connection D, a source connection S, and a gate connection G. By means of the gate connection G, the electrical resistance between the source S and the drain D can be configured such that the load or power dissipation in the sensor element SE on the right side of Fig. 3 is controlled and limited to a non-critical value.

[0061] In the configuration shown in FIG. 3, each sensor stage SST is connected to the same potential supplied by a voltage source.

[0062] In contrast, Fig. 4 shows a variant of several sensor stages SST, in which in each sensor stage the sensor element controller SEC is realised as a BJT (BJT = Bipolar Junction Transistor) as shown on the left side of Fig. 4. The BJT comprises a collector connection C, an emitter connection E and a base connection B, by means of which the operation of the controller SEC can be determined.

[0063] Also, similar to the version shown in FIG. 3, each sensor stage SST is connected to the same potential.

[0064] In contrast to this, FIG. 5 shows a version in which individual power lines power each individual sensor stage SST.

[0065] FIG. 6 shows a possible realization of a temperature controller circuit TCC including four parallel sensor stages SSTI, SSTII, SSTIII, SSTIV. Each sensor stage SST includes a thermistor electrically connected in series with a semiconductor switch. One electrode of the thermistor, which realizes the sensor element, is connected to a voltage supply line, and the other electrode of the thermistor is connected to a semiconductor switch and a voltage divider VD. Each semiconductor switch of each stage SST realizes a sensor element controller and is connected to ground through a shunt circuit element. Each voltage divider VD includes resistive elements connected in series, the ratio of the resistance values ​​of the resistive elements determines the voltage conversion ratio. Each of the active semiconductor switches realizing the sensor element controller SEC is coupled to an input operational amplifier, such that there are four input operational amplifiers for the four stages I, II, III, IV. The input operational amplifier OPAMP is connected between the semiconductor switch and a voltage converter VC, which is arranged between the evaluation circuit EVC and the corresponding input operational amplifier. The voltage converter VC includes two operational amplifiers electrically connected in series.

[0066] Furthermore, by a corresponding voltage divider VD, each sensor stage SST is connected via an output operational amplifier to an ADC, which converts the analog signal of the operational amplifier into an additional signal processed by an evaluation circuit EVC. The ADC obtains its power or electrical signal from an additional operational amplifier, which obtains its power from an additional voltage divider VD connected to a voltage source VS.

[0067] Furthermore, the evaluation circuit EVC is coupled to a display DSP which provides a light rendition of the measured temperature.

[0068] The temperature controller circuit is not limited to the technical details given above, and may include additional circuit elements, such as additional overvoltage protection elements or additional circuit elements for providing electrical energy. [Explanation of symbols]

[0069] B Base connection C Collector connection CH Chip D drain connection DISP Display E Emitter connection EVC evaluation circuit G Gate connection OPAMP Operational Amplifier S Source Connection SE sensor element SEC Sensor Element Controller SL Solder length SST Sensor Stage THE Thermistor TCC Temperature Controller Circuit VC Voltage Converter VD Voltage divider VS Voltage Supply WI Wire

Claims

1. An evaluation circuit (EVC); two or more sensor stages (SSTs); Each sensor stage includes a sensor element and a sensor element controller; The sensor stage is electrically connected in parallel to a temperature controller circuit.

2. 10. A temperature controller circuit as claimed in any preceding claim, wherein the sensor elements of each stage are selected from temperature dependent resistive elements, thermistors, NTC elements, PTC elements.

3. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein the sensor element controller of each stage comprises an active element selected from a voltage controlled element, a MOSFET, a current controlled element, a BJT, a controlled current source.

4. 2. A temperature controller circuit as claimed in any one of the preceding claims, wherein in each sensor stage the sensor element and the sensor element controller are connected in series or electrically in parallel.

5. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein the evaluation circuit is selected from a computer, a microcontroller, an ASIC and an FPGA.

6. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein each sensor stage includes an operational amplifier which drives the sensor element controller.

7. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein each sensor stage includes an output operational amplifier.

8. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein each sensor stage includes a voltage divider.

9. 10. The temperature controller circuit of claim 1, further comprising an ADC electrically connected to an input of the evaluation circuit.

10. 10. The temperature controller circuit of claim 1, further comprising a voltage divider electrically connected to the ADC.

11. 10. A temperature controller circuit as claimed in any one of the preceding claims, further comprising a voltage converter between the output of the evaluation circuit and the input of each sensor stage.

12. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein the voltage converter comprises two operational amplifiers.

13. 10. A temperature controller circuit as claimed in any one of the preceding claims, further comprising a low pass filter including a series inductance element and a shunt capacitance element.

14. 10. A temperature controller circuit as claimed in any one of the preceding claims, wherein the number of sensor stages is greater than 2, greater than 10, greater than 100 or greater than 1000.

15. 10. A temperature controller circuit as claimed in any one of the preceding claims, further comprising a display for continuously monitoring the presence of a faulty sensor stage.

16. A temperature sensor arrangement comprising a temperature controller circuit according to any one of the preceding claims.

17. 10. A temperature sensor arrangement according to the previous claim, wherein the sensor stage circuitry or the evaluation circuitry is provided within a chip which contains the sensor element.

18. 20. A temperature sensor arrangement according to any one of the preceding claims, further comprising a thermal insulation portion of the sensor element.

19. 2. The temperature sensor device according to claim 1, wherein the heat insulating part comprises a wire used in the sensor element, the thermal conductivity of the wire being lower than the thermal conductivity of copper (Cu) or aluminum (Al).

20. 13. A method of detecting temperature utilizing a temperature sensor device according to any one of the preceding claims, comprising distributing temperature detection over two or more sensor stages whilst controlling the power or load of each sensor stage.

21. 10. A method according to the preceding claim, comprising the step of determining and / or measuring the current through one, several or all of the sensor elements.

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