Temperature detection circuit

Abstract

The present disclosure provides a temperature detection circuit, which includes: a resistor driving circuit connected to a reference voltage to generate a driving voltage and a control voltage according to the reference voltage; a resistor trimming network for selecting a resistor conduction path according to the foregoing driving voltage, control voltage, and switch control signal to provide a detection current to a thermistor; the thermistor, the first end of the thermistor serves as the output end of the temperature detection circuit and is connected to the output end of the resistor trimming network to access the detection current to provide a detection voltage, wherein the detection voltage is used to characterize the temperature value detected by the temperature detection circuit. The temperature detection circuit reduces the influence of the switch element resistance on the resistor trimming network by changing the position of the input end node of the feedback path, improves the resistor trimming accuracy, and at the same time allows the switch transistor to have a smaller size, effectively reducing the circuit area, which is beneficial to the miniaturization of the integrated circuit chip.

Description

Technical Field

[0001] The present disclosure relates to the field of integrated circuit technology, and particularly to a temperature detection circuit based on a thermistor. Background Art

[0002] In order to ensure the working safety of mobile phone devices, intelligent terminal devices, batteries, etc., the temperatures of these devices are detected. Currently, the most widely used method is to implement it through a resistor voltage division scheme.

[0003] In a temperature detection circuit, a circuit structure that can be used to convert a temperature quantity into a voltage quantity is as Figure 1 shown. The operational amplifier is connected in a negative feedback form, and a reference voltage is connected to its non-inverting input terminal. After being amplified by the operational amplifier in a closed loop, a driving voltage VC can be obtained at the output terminal TOPA of the operational amplifier. A resistor R with a known resistance value is connected in series with a negative temperature coefficient thermistor (NTC) and connected to TOPA. At this time, the output voltage VOUT of the overall circuit is the voltage division of R and NTC.

[0004] In this circuit structure, the NTC is placed outside the chip, and the rest of the structure is placed inside the chip. Ideally, the driving voltage VC and the resistance value of R remain unchanged all the time. When the temperature changes, the resistance value of the NTC changes accordingly, causing the change of the output voltage VOUT. Therefore, by collecting the voltage at the VOUT terminal, the actual resistance value of the NTC can be calculated, and then the temperature value to be measured can be obtained by looking up a table.

[0005] Figure 1 The size of the resistor R in directly affects the voltage at the VOUT terminal, so a high precision requirement is imposed on it. In practice, process variations will cause the resistance value of this resistor to change, so this resistor needs to be trimmed. A conventional resistor trimming structure is as Figure 2 shown. This structure consists of two parts, namely a fixed resistor RC and a resistor R0 for trimming, and there are two ports, which is applicable to Figure 1 the driving circuit structure of the NTC resistor shown. Its TOP terminal is connected to the output terminal of the operational amplifier, and the BOT terminal is connected to the NTC.

[0006] Figure 2 In the structure of the conventional resistor trimming circuit shown, one end of the switch for selecting the trimming resistor is connected to the trimming resistor network, and the other end is used as the TOP terminal and connected to the top layer circuit TOPA. By selecting and closing the switch at an appropriate position, the trimming of the resistor can be realized, and the actually trimmed resistance value is:

[0007] R = RC + n * R0 + Ron (1)

[0008] Among them, RC is a fixed resistor, R0 is the unit resistor in the trimming resistor part, n is the number of selected unit resistors, and Ron is the on-resistance of the switch. It can be seen from the formula that the on-resistance of the switch directly affects the accuracy of the trimmed resistor value, and Ron is not a fixed value, which changes with the variation of process, voltage, and temperature (PVT).

[0009] Therefore, there is a problem of poor trimming accuracy in the temperature detection circuit of the above prior art. The conventional solution is to reduce its on-resistance by increasing the gate width of the switch transistor, but to reduce it to a small enough value, a large circuit area is required. Summary of the Invention

[0010] To solve the above technical problems, the present disclosure provides a temperature detection circuit.

[0011] The present disclosure provides a temperature detection circuit, which includes:

[0012] A resistor driving circuit, having a first input terminal connected to a reference voltage, a second output terminal providing a control voltage to a feedback path, and a first output terminal providing a driving voltage, for generating the driving voltage and the control voltage according to the reference voltage;

[0013] A resistor trimming network, which is connected to the resistor driving circuit, for selecting a resistor conduction path according to the foregoing driving voltage, control voltage, and switch control signal to provide a detection current to the thermistor;

[0014] A thermistor, the first end of which is used as the output terminal of the temperature detection circuit, and is connected to the output terminal of the resistor trimming network to access the detection current to provide a detection voltage, and the second end of the thermistor is grounded.

[0015] Among them, the detection voltage is used to represent the temperature value detected by the temperature detection circuit.

[0016] Preferably, the foregoing resistor trimming network includes:

[0017] A plurality of first resistors and second resistors, the plurality of first resistors are sequentially connected in series between the first input terminal and the second resistor, the first end of the second resistor is connected to the last first resistor among the foregoing plurality of first resistors, and the second end is used as the output terminal of the resistor trimming network to provide the foregoing detection current;

[0018] A plurality of switching elements, the first ends of the plurality of switching elements are sequentially connected to the connection node between the first output terminal and the foregoing plurality of first resistors and the connection node between the last first resistor and the second resistor, and the second ends are commonly connected to the second output terminal.

[0019] Preferably, the specifications of the foregoing multiple first resistors are the same, and the second resistor is a resistor with a fixed resistance value.

[0020] Preferably, the specifications of the foregoing multiple switching elements are the same, and the foregoing switching control signal includes multiple switching signals, and the multiple switching signals are respectively provided to the control terminals of the foregoing multiple switching elements to select the number of the foregoing multiple first resistors actually connected.

[0021] Preferably, the foregoing resistor driving circuit includes:

[0022] an operational amplifier, configured to amplify the reference voltage applied to the first input terminal to generate the foregoing driving voltage, and provide it to the resistor trimming network through the first output terminal; and

[0023] a feedback path, serially connected between the second output terminal and the ground, and connected to the operational amplifier through any one of the connection nodes therein to provide a feedback voltage, and provide a control voltage through the foregoing second output terminal.

[0024] Preferably, the positive input terminal of the foregoing operational amplifier is applied with the foregoing reference voltage, the negative input terminal is applied with the foregoing feedback voltage, and its output terminal provides the foregoing driving voltage.

[0025] Preferably, the foregoing feedback path includes:

[0026] a third resistor and a fourth resistor, and the connection node between the third resistor and the fourth resistor is used to provide the foregoing feedback voltage.

[0027] Preferably, any one of the foregoing multiple switching elements is a single-pole single-throw switch or a field-effect transistor device.

[0028] Preferably, the foregoing resistor trimming network and the resistor driving circuit are integrated on the same chip, and the thermistor is used as an external device of the chip, and the first end of the thermistor is connected to the second end of the second resistor in the chip through an output pin.

[0029] The beneficial effects of the present disclosure are as follows: A temperature detection circuit provided by the present disclosure includes: a resistor driving circuit having a first input terminal connected to a reference voltage, a second output terminal connected to a control voltage provided to a feedback path, and a first output terminal for providing a driving voltage, configured to generate a driving voltage and a control voltage based on the reference voltage; a resistor trimming network connected to the resistor driving circuit, configured to select a current flow path thereof according to the aforementioned driving voltage, control voltage, and a switch control signal to provide a detection current for a thermistor; and a thermistor, a first end of the thermistor serving as an output terminal of the temperature detection circuit and connected to an output terminal of the resistor trimming network to access the detection current to provide a detection voltage, a second end of the thermistor being grounded, wherein the detection voltage is used to represent a temperature value detected by the temperature detection circuit. On the one hand, the temperature detection circuit reduces the influence of the switch element resistance on the resistor trimming network by changing the position of the input terminal node of the feedback path. On the other hand, by increasing the resistance value of the feedback resistor to reduce the control current, if the control current is reduced to 1 / 10 of the minimum detection current, the influence of the switch element resistance on the resistor trimming circuit in the improved resistor trimming network is reduced by at least 10 times compared with the conventional structure, greatly improving the resistor trimming accuracy. At the same time, a smaller size of the switching transistor is allowed, effectively reducing the circuit area, which is beneficial to the miniaturization of the integrated circuit chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure with reference to the accompanying drawings.

[0031] Figure 1 FIG. shows a schematic structural diagram of a temperature detection circuit provided in the prior art;

[0032] Figure 2 shows Figure 1 a schematic structural diagram of a resistor trimming circuit in the temperature detection circuit shown;

[0033] Figure 3 FIG. shows a schematic structural diagram of a temperature detection circuit based on a thermistor provided by the present disclosure;

[0034] Figure 4 shows Figure 3 a schematic structural diagram of a resistor trimming network in the temperature detection circuit shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To facilitate the understanding of the present disclosure, the present disclosure will be described more comprehensively below with reference to the relevant accompanying drawings. Preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the content of the present disclosure more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this disclosure belongs. The terms used in the specification of this disclosure are for the purpose of describing specific embodiments only and are not intended to limit this disclosure.

[0037] As Figure 1 shown, the reference voltage VBG is amplified through closed-loop feedback to obtain a constant driving voltage VC. This driving voltage VC is applied to the series structure composed of the resistor R and the NTC. Ideally, when the temperature to be measured changes, only the resistance value of the NTC changes, thereby causing a change in the voltage applied to the NTC. By collecting this voltage, the actual resistance value of the NTC can be obtained, and then the temperature value to be measured can be obtained by looking up a table.

[0038] Affected by the process, the resistance value of the resistor R will change, and it needs to be trimmed. When trimming by existing technical means, by selecting and closing Figure 2 the switches in the resistor trimming network structure shown, the adjustment of the number of resistors connected to the main path can be achieved, thereby completing the trimming of the resistor resistance value. However, there is a problem that the on-resistance of the switch directly affects the accuracy of the trimmed resistor resistance value, and the on-resistance of the switch is not a fixed value and changes with PVT. By increasing the gate width of the switch transistor, its on-resistance can be reduced, but to reduce it to a small enough value, a large circuit area needs to be consumed.

[0039] Based on this, the temperature detection circuit provided in the embodiments of this disclosure is proposed. It can reduce the current flowing through the switch branch in the resistor trimming network by increasing the resistance value of the feedback resistor, thereby reducing the influence of the switch resistance, improving the trimming accuracy, and at the same time allowing the switching element to take a smaller size, which is beneficial to reducing the circuit area.

[0040] Next, this disclosure will be described in detail with reference to the accompanying drawings.

[0041] Figure 3 shows a schematic structural diagram of a temperature detection circuit based on a thermistor provided by this disclosure, Figure 4 shows Figure 3 a schematic structural diagram of the resistor trimming network in the temperature detection circuit shown.

[0042] As Figure 3 shown, the embodiments of this disclosure provide a temperature detection circuit 200, which includes: a resistor driving circuit 210, a resistor trimming network 220, and a thermistor NTC, wherein,

[0043] The resistor driving circuit 210 has a first input terminal VIN for accessing the reference voltage VBG, a second output terminal TRF for providing the control voltage VT to the feedback path 211, and a first output terminal TOP for providing the driving voltage VC ( Figure 3where I2 is the drive current), for generating a drive voltage VC and a control voltage VT according to the reference voltage VBG;

[0044] The resistor trimming network 220 is connected to the resistor drive circuit 210, and is used to select and conduct a resistor conduction path according to the aforementioned drive voltage VC, control voltage VT, and switch control signal, so as to provide a detection current I3 to the thermistor NTC;

[0045] The first end of the thermistor NTC serves as the output end BOT of the temperature detection circuit 200, and is connected to the output end of the resistor trimming network 220 to access the detection current I3, so as to provide a detection voltage Vout. The second end of the thermistor NTC is grounded.

[0046] Wherein, the detection voltage Vout is used to represent the temperature value detected by the temperature detection circuit 200.

[0047] Furthermore, in this embodiment, the temperature detection circuit 200 may further include an ADC module. The ADC module can be used to inversely deduce the temperature to be measured according to the detection voltage Vout when the detection voltage Vout meets the input range of the ADC module. Specifically, when the temperature to be measured changes, only the resistance value of the NTC changes, thereby causing a change in the voltage applied to the NTC. By collecting this voltage, the actual resistance value of the NTC can be obtained, and then the temperature to be measured can be obtained by looking up a table.

[0048] Furthermore, referring to Figure 4 , in this embodiment, the aforementioned resistor trimming network 220 includes:

[0049] A plurality of first resistors R1 (for example, m in this embodiment, the same below) and a second resistor R2. The plurality of first resistors R1 are connected in series between the first input terminal VIN and the second resistor R2 in sequence. The first end of the second resistor R2 is connected to the last first resistor R1 among the aforementioned plurality of first resistors R1, and the second end serves as the output end BOT of the resistor trimming network 220 for providing the aforementioned detection current I3;

[0050] A plurality of switching elements (for example, K0 to Km, a total of m + 1 in this embodiment, the same below). The first ends of the plurality of switching elements (K0 to Km) are sequentially connected to the connection node between the first output terminal TOP and the aforementioned plurality of first resistors R1 and the connection node between the aforementioned last first resistor R1 and the second resistor R2, and the second ends are commonly connected to the second output terminal TRF.

[0051] Furthermore, in this embodiment, the specifications of the aforementioned plurality of first resistors R1 are the same, and the second resistor R2 is a resistor with a fixed resistance value.

[0052] Further, in this embodiment, the specifications of the foregoing multiple switching elements (K0 to Km) are the same, and the foregoing switching control signal includes multiple switching signals (S0 to Sm), and the multiple switching signals (S0 to Sm) are respectively provided to the control terminals of the foregoing multiple switching elements (K0 to Km) to select the number of the foregoing multiple first resistors R1 actually connected.

[0053] Further, referring to Figure 3 , in this embodiment, the foregoing resistor driving circuit 210 includes:

[0054] An operational amplifier OPA for generating the foregoing driving voltage VC from the reference voltage VBG connected to the first input terminal VIN and providing the driving voltage VC to the resistor trimming network 220 through the first output terminal TOP; and

[0055] A feedback path 211, connected in series between the second output terminal TRF and the ground, and connected to the operational amplifier OPA through any one of the connection nodes therein to provide a feedback voltage VFB, and providing the control voltage VT through the second output terminal TRF.

[0056] Specifically, the positive input terminal of the foregoing operational amplifier OPA serves as the foregoing first input terminal VIN to connect the foregoing reference voltage VBG, the negative input terminal connects the foregoing feedback voltage VFB, and its output terminal provides the foregoing driving voltage VC.

[0057] Further, in this embodiment, the foregoing feedback path 211 includes:

[0058] A third resistor R3 and a fourth resistor R4, and the connection node between the third resistor R3 and the fourth resistor R4 is used to provide the foregoing feedback voltage VFB.

[0059] Further, in this embodiment, any one of the foregoing multiple switching elements (K0 to Km) is a single-pole single-throw switch (SPST) or a metal oxide semiconductor field effect transistor (MOSFET, hereinafter simply referred to as MOS transistor) device.

[0060] Further, as Figure 3 shown, in this embodiment, the foregoing resistor trimming network 220 and the resistor driving circuit 210 are integrated on the same chip, and the thermistor NTC is an external device of the chip, and the first end of the thermistor NTC is connected to the second end of the second resistor R2 in the chip through an output pin.

[0061] Combined with Figure 2 , Figure 3 andFigure 4 To understand the temperature detection circuit 200 provided in this embodiment, in this embodiment, the first output terminal TOP and the second output terminal BOT connected to the improved resistor trimming network 220 are respectively connected to the output terminal of the operational amplifier OPA and the first terminal of the thermistor NTC, and the second output terminal TRF of the feedback path 211 is disconnected from the output terminal of the operational amplifier OPA, so as to reduce the influence of the switch element resistance on the resistor trimming network 220 by changing the position of the input terminal node of the feedback path 211. At this time, the control voltage VT for driving the thermistor NTC determined by this feedback structure is transferred from the output terminal of the operational amplifier OPA to the second output terminal TRF, and its value remains unchanged. For the underlying resistor trimming network 220, the control voltage VT is applied to the second output terminal TRF. At this time, the actually trimmed resistance value R can be expressed as:

[0062]

[0063] Among them, RC is the resistance value of the fixed resistor (i.e., the second resistor R2), R0 is the resistance value of the unit resistor (i.e., the first resistor R1) in the trimming resistor network 220, n is the number of selected unit resistors, Ron is the on-resistance of the switch element, I1 is the sum of the branch currents flowing through the switch element, that is, the current value of the control current I1, and I3 is the current value of the detection current I3 flowing through the NTC. Comparing Equation (2) with Equation (1), it can be seen that in the improved temperature detection circuit 200, the influence of the on-resistance of the switch element on the resistor trimming network 220 is I1 / I3 times that of the conventional structure. Among them, the control voltage VT is determined by the reference voltage VBG and the resistance values in the feedback path 211, and the detection current I3 changes with the change of the thermistor NTC. Therefore, the magnitude of the control current I1 can be reduced by increasing the resistance values of the feedback resistors (R3 and R4). If it is reduced to 1 / 10 of the minimum detection current I3, the influence of the on-resistance of the switch element in the improved resistor trimming network 220 on the temperature detection circuit 200 is reduced by at least 10 times compared with the conventional structure, which is extremely beneficial to the improvement of the trimming accuracy. At the same time, it allows the switch element (taking the MOS transistor as an example) to have a smaller size, which is beneficial to the reduction of the circuit area.

[0064] In summary, on the one hand, the temperature detection circuit 200 provided by the present disclosure reduces the influence of the switch element resistance on the temperature detection circuit 200 by changing the position of the input terminal node of the feedback path 211. On the other hand, by increasing the resistance value of the feedback resistor to reduce the control current I1, if it is reduced to 1 / 10 of the minimum detection current I3, the influence of the on-resistance of the switch element in the improved resistor trimming network 220 on the temperature detection circuit 200 is reduced by at least 10 times compared with the conventional structure, greatly improving the resistor trimming accuracy. At the same time, it allows the switch element to have a smaller size, effectively reducing the circuit area, which is beneficial to the miniaturization of the integrated circuit chip.

[0065] It should be noted that in the description of the present disclosure, it should be understood that the terms "upper", "lower", "inner", etc. indicating orientation or positional relationships are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present disclosure.

[0066] In addition, in this text, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0067] Finally, it should be noted that: Obviously, the above embodiments are merely examples given for clearly illustrating the present disclosure and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present disclosure.

Claims

1. A temperature detection circuit, characterized in that, it includes: A resistor driving circuit, having a first input terminal for accessing a reference voltage, a second output terminal for providing a control voltage to a feedback path, and a first output terminal for providing a driving voltage, configured to generate the driving voltage and the control voltage according to the reference voltage; A resistor trimming network, the resistor trimming network is connected to the resistor driving circuit, and is configured to select a resistor conduction path according to the driving voltage, the control voltage, and a switch control signal to provide a detection current to a thermistor; A thermistor, a first end of the thermistor serves as an output terminal of the temperature detection circuit, and is connected to an output terminal of the resistor trimming network to access the detection current to provide a detection voltage, and a second end of the thermistor is grounded, wherein, the detection voltage is used to characterize the temperature value detected by the temperature detection circuit.

2. The temperature detection circuit according to claim 1, characterized in that, the resistor trimming network includes: A plurality of first resistors and a second resistor, the plurality of first resistors are sequentially connected in series between the first input terminal and the second resistor, a first end of the second resistor is connected to the last first resistor among the plurality of first resistors, and a second end serves as an output terminal of the resistor trimming network for providing the detection current; A plurality of switch elements, a first end of the plurality of switch elements are sequentially connected to connection nodes between the first output terminal and the plurality of first resistors and connection nodes between the last first resistor and the second resistor, and a second end is commonly connected to the second output terminal.

3. The temperature detection circuit according to claim 2, characterized in that, the plurality of first resistors have the same specification, and the second resistor is a resistor with a fixed resistance value.

4. The temperature detection circuit according to claim 3, characterized in that, the plurality of switch elements have the same specification, and the switch control signal includes a plurality of switch signals, and the plurality of switch signals are respectively provided to control terminals of the plurality of switch elements to select the number of actually connected first resistors among the plurality of first resistors.

5. The temperature detection circuit according to claim 4, characterized in that, the resistor driving circuit includes: An operational amplifier, configured to amplify the reference voltage accessed by the first input terminal to generate the driving voltage, and provide it to the resistor trimming network through the first output terminal; and The feedback path, connected in series between the second output terminal and the ground, and connected to the operational amplifier through any one of the connection nodes therein to provide a feedback voltage, and provide the control voltage through the second output terminal.

6. The temperature detection circuit according to claim 5, characterized in that, a positive input terminal of the operational amplifier accesses the reference voltage, a negative input terminal accesses the feedback voltage, and an output terminal provides the driving voltage.

7. The temperature detection circuit according to claim 6, characterized in that, the feedback path includes: A third resistor and a fourth resistor, a connection node between the third resistor and the fourth resistor is used to provide the feedback voltage.

8. The temperature detection circuit according to claim 7, wherein, any one of the plurality of switching elements is a single-pole single-throw switch or a field effect transistor device.

9. The temperature detection circuit according to claim 8, wherein, the resistor trimming network and the resistor driving circuit are integrated on the same chip, and the thermistor is an external device of the chip, and a first end of the thermistor is connected to a second end of the second resistor in the chip through an output pin.

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