Over-temperature protection circuit and test method thereof

Abstract

The application discloses an over-temperature protection circuit and a testing method thereof, which comprises a signal generating circuit, a reference voltage circuit, a temperature detecting circuit and a bias current circuit. The signal generating circuit is used for outputting a control signal and comprises a voltage comparator; the reference voltage circuit is coupled to one input end of the voltage comparator and is used for providing a switchable reference voltage in response to the control signal; the temperature detecting circuit detects temperature through the relationship between a PN junction voltage and temperature and is coupled to another input end of the voltage comparator; and the bias current circuit is used for outputting a variable bias current and is used for adjusting the PN junction voltage to obtain an accurate junction voltage value. The over-temperature protection circuit of the application can adjust the junction voltage value by adding the bias current circuit, so that the over-temperature protection circuit does not need to provide a high-temperature environment in the testing process, the testing difficulty is reduced, the testing precision is improved, and the safe operation of the electronic device where the over-temperature protection circuit is located is facilitated.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an over-temperature protection circuit and its testing method. Background Technology

[0002] As integrated circuit products advance towards integration and miniaturization, existing integrated circuit products, such as power supplies and processor chips, often face the problem of excessively high ambient temperatures causing devices to malfunction or even burn out. Therefore, existing chips are equipped with over-temperature protection circuits. The function of the over-temperature protection circuit is to stop the chip from working or enter a low-power mode when the ambient temperature of the chip exceeds a set value, allowing the chip temperature to gradually decrease; and to allow the chip to re-enter the working mode when the chip temperature falls below another set value.

[0003] In existing technologies, during chip manufacturing, the over-temperature protection circuit needs to be tested and calibrated to ensure it operates at a set temperature. However, testing often requires the use of high-temperature chambers or similar equipment to provide a high-temperature environment for the chip under test. This not only increases the difficulty of testing but also increases the error during calibration, which is detrimental to the safe operation of the chip.

[0004] Therefore, a new over-temperature protection circuit is needed to enable simple and accurate testing of the over-temperature protection circuit. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide an over-temperature protection circuit and its testing method, thereby achieving accurate testing and calibration of the over-temperature protection circuit at room temperature.

[0006] According to one aspect of the present invention, an over-temperature protection circuit is provided, characterized in that it comprises:

[0007] A signal generation circuit includes a first input terminal and a second input terminal, the signal generation circuit being used to output a control signal; a reference voltage circuit is coupled to the first input terminal of the signal generation circuit, the reference voltage circuit responding to the control signal and outputting a switchable reference voltage to the first input terminal; a temperature detection circuit is coupled to the second input terminal of the signal generation circuit, the temperature detection circuit being used to output a temperature coefficient voltage responding to temperature to the second input terminal; a bias current circuit is coupled to the temperature detection circuit, the bias current being used to adjust the temperature coefficient voltage.

[0008] Optionally, the bias current circuit includes a current regulation module and a current output module. The current regulation module includes a constant current input terminal and a current output port. The current output module includes a current receiving port and at least one output terminal. The current output port is connected to the current receiving port.

[0009] Optionally, the current regulation module includes multiple current mirror branches, which are respectively coupled between the constant current input terminal and ground or between the current output port and ground to form a current mirror structure for replicating the constant current received by the constant current input terminal.

[0010] Optionally, the current regulation module includes at least one switching transistor coupled between the current output port and the current mirror branch, for controlling the output current of the current output port.

[0011] Optionally, the at least one switching transistor is a MOSFET.

[0012] Optionally, the current mirror branch coupled between the current output port and ground includes multiple current mirror branches with different specifications. The multiple current mirror branches with different specifications are used to replicate the constant current at different ratios, so that the current output port outputs a non-linearly changing current. The non-linearly changing current is used to make the temperature coefficient voltage change linearly.

[0013] Optionally, the current output module includes multiple current mirror branches, which are respectively coupled between the output terminal and ground or between the current receiving port and ground, forming a current mirror structure.

[0014] Optionally, the multiple current mirror branches have the same specifications, and the output current of the output terminal is the same as the received current of the current receiving port.

[0015] Optionally, the temperature detection circuit includes a first bipolar transistor, the base and collector of the first bipolar transistor are shorted and grounded, the emitter of the first bipolar transistor is coupled to the first output terminal, the first output terminal outputs a bias current to adjust the PN junction voltage between the emitter and the base, the PN junction voltage responds to the temperature and is output to the second input terminal as the temperature coefficient voltage.

[0016] Optionally, the temperature detection circuit includes a second bipolar transistor, the emitter of the second bipolar transistor is shorted to the base of the first bipolar transistor and coupled to the second output terminal, the base and collector of the second bipolar transistor are shorted to and coupled to the collector of the first bipolar transistor, and the second bipolar transistor is used to improve the temperature coefficient voltage output by the temperature detection circuit.

[0017] Optionally, the temperature detection circuit includes a plurality of bipolar transistors, the number of which is the same as the output terminal of the bias current circuit.

[0018] Optionally, the reference voltage circuit includes a first switching transistor, a second switching transistor, and a reference voltage output terminal. The first and second switching transistors each have an input terminal, an output terminal, and a control terminal. The output terminals of both the first and second switching transistors are coupled to the reference voltage output terminal. The input terminal of the first switching transistor has a first reference voltage, and the input terminal of the second switching transistor has a second reference voltage. The reference voltage output terminal is connected to the first input terminal. The first reference voltage corresponds to a first preset temperature, and the second reference voltage corresponds to a second preset temperature.

[0019] Optionally, the first switch and the second switch are MOSFETs.

[0020] Optionally, the signal generation circuit includes a voltage comparator, a first NOT gate, and a second NOT gate. The input terminals of the voltage comparator are respectively connected to the first input terminal and the second input terminal, and the first NOT gate and the second NOT gate are sequentially coupled to the output terminal of the voltage comparator.

[0021] Optionally, the output terminals of the first NOT gate and the second NOT gate are respectively coupled to the control terminals of the first switch and the second switch.

[0022] Optionally, the conduction states of the first and second switching transistors respond to control signals output by the first and second NOT gates. These control signals control the reference voltage circuit to alternately output the first and second reference voltages to control the temperature between a first preset temperature and a second preset temperature. According to another aspect of the invention, a testing method for an over-temperature protection circuit is provided, characterized by comprising: a temperature measurement step, maintaining the temperature of the over-temperature protection circuit constant and measuring this constant temperature; a voltage calculation step, calculating the junction voltage at the constant temperature based on the specifications of the first and second bipolar transistors, the first and second reference voltages, and the first and second preset temperatures; and a voltage adjustment step, adjusting a variable bias current so that the temperature coefficient voltage output by the temperature detection circuit corresponds to the calculated junction voltage.

[0023] Optionally, the nonlinear change of the variable reference current in the reference voltage determination step is used to make the junction voltage change linearly.

[0024] The over-temperature protection circuit provided by this invention improves upon existing over-temperature protection circuits by adding a bias current circuit to provide bias current to the bipolar transistor used as a temperature sensor. It should be understood that the PN junction voltage is inversely proportional to its temperature, and the junction voltage is a fixed value when the PN junction is at absolute zero. The bias current circuit of this invention can provide a variable bias current, and the PN junction voltage can be adjusted by controlling the magnitude of the bias current. Specifically, the junction voltage value of the PN junction at room temperature (27°C) can be calculated from the known junction voltage values ​​at absolute zero and a preset temperature. By adjusting the PN junction voltage to the calculated value at room temperature using the bias current circuit, the over-temperature protection circuit can be controlled to achieve precise operation. The over-temperature protection circuit of this invention avoids the need for complex equipment such as high-temperature chambers during testing, and also avoids junction voltage errors caused by temperature errors, thus improving the safety of chip operation. Attached Figure Description

[0025] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0026] Figure 1 A schematic diagram of an over-temperature protection circuit according to the prior art is shown;

[0027] Figure 2 A schematic block diagram of an over-temperature protection circuit according to an embodiment of the present invention is shown;

[0028] Figure 3 A schematic diagram of an over-temperature protection circuit according to an embodiment of the present invention is shown;

[0029] Figure 4 The relationship between the junction voltage of a PN junction and temperature is shown.

[0030] Figure 5 It shows that according to Figure 3 A schematic diagram of the bias current circuit 300 in the illustrated embodiment. Detailed Implementation

[0031] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements or modules are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0032] It should be understood that in the following description, when a component or circuit is said to be "connected to" another component or "connected" between two nodes, it can be directly coupled or connected to the other component or there can be intermediate components. The connection between components can be physical, logical, or a combination thereof. Conversely, when a component is said to be "directly coupled to" or "directly connected to" another component, it means that there are no intermediate components between them.

[0033] Furthermore, certain terms are used in this patent specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This patent specification and claims do not distinguish components based on differences in name, but rather on differences in function.

[0034] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] Over-temperature protection circuits are commonly found in various chips. Due to the high integration density of circuits within chips, the heat generated during circuit operation cannot be dissipated in time, causing the chip temperature to rise with increasing operating time. It should be understood that the chip's operating state is affected by its temperature; for example, excessively high chip temperatures can lead to chip burnout. To ensure that the chip's temperature remains within a safe range during operation, it is necessary to incorporate over-temperature protection circuits. Figure 1 An existing over-temperature protection circuit is shown, which is used to keep the chip operating within a safe temperature range.

[0036] Figure 1A schematic diagram of an over-temperature protection circuit according to the prior art is shown. As shown, the over-temperature protection circuit in the prior art uses a feedback regulation method to ensure that the chip temperature is below a predetermined value. Specifically, the over-temperature protection circuit in the prior art includes a bipolar transistor Q1, a signal generation circuit 100, and a reference voltage circuit 200. The bipolar transistor Q1 acts as a temperature sensor. Specifically, the base and collector of the bipolar transistor Q1 are shorted, and the PN junction voltage Vbe between the base and emitter is inversely proportional to its temperature. This PN junction voltage Vbe is used to determine the chip temperature. The reference voltage circuit 200 includes a reference voltage output terminal 210 and two MOSFETs M1 and M2. The two MOSFETs M1 and M2 act as switching transistors to provide different reference voltages V1 and V2 to the reference voltage output terminal 210. The signal generation circuit 100 includes a comparator 110. Two NOT gates, U1 and U2, are connected. The base and collector of the reference voltage output terminal 210 and the bipolar transistor Q1 are respectively coupled to the two input terminals of the comparator 110. The NOT gate U2 is cascaded with U1, and U2 is positively connected between the output terminal of the comparator 110 and the input terminal of U1. The output terminal otp1 of the NOT gate U1 is coupled to the gate of the MOS transistor M1, and the output terminal otp2 of the NOT gate U2 is coupled to the gate of the MOS transistor M2. The output signals of the NOT gates U1 and U2 are used to adjust the working state of the chip and control the switching state of the MOS transistors M1 and M2.

[0037] The drawback of existing over-temperature protection circuits is that they require a high-temperature environment for functional testing. This is because, according to the relationship between PN junction voltage and temperature, the junction voltage only reaches the reference voltage range when the circuit is in a high-temperature environment. Technicians should understand that in high-temperature environments, such as high-temperature chambers, it is difficult to accurately control the temperature of the PN junction. This not only increases the difficulty of testing the over-temperature protection circuit but also leads to larger test errors.

[0038] Figure 2 A schematic block diagram of an over-temperature protection circuit according to an embodiment of the present invention is shown. The over-temperature protection circuit of the present invention includes a signal generation circuit 100, a reference voltage circuit 200, a bias current circuit 300, and a temperature detection circuit 400. The bias current circuit 300 is coupled to the temperature detection circuit 400 and provides a variable bias current. The bias current is used to adjust the temperature coefficient voltage output by the temperature detection circuit 300, and the temperature coefficient voltage also responds to the ambient temperature. The signal generation circuit 100 is coupled to both the reference voltage circuit 200 and the temperature detection circuit 400 to receive a reference voltage and a temperature coefficient voltage representing a set temperature. The signal generation circuit 100 compares the two signals and outputs a control signal based on the result. The control signal is used to control the reference voltage output by the reference voltage circuit 200 and the operating state of the circuit containing the over-temperature protection circuit.

[0039] Figure 3 A schematic diagram of an over-temperature protection circuit according to an embodiment of the present invention is shown. The over-temperature protection circuit includes a signal generation circuit 100, a reference voltage circuit 200, a bias current circuit 300, and a temperature detection circuit 400. The bias current circuit 300 is coupled to the temperature detection circuit 400 and provides an adjustable bias current to the temperature detection circuit 400. The signal generation circuit 100 includes a voltage comparator 110, and the reference voltage circuit 200 and the temperature detection circuit 400 are respectively coupled to two input terminals of the voltage comparator 110. The signal generation circuit 100 outputs a control signal by comparing the voltages at the two input terminals. This control signal is used to control the operating state of the chip and the reference voltage output by the reference voltage circuit 200.

[0040] The temperature detection circuit 400 of the over-temperature protection circuit of the present invention uses a temperature-sensitive device as a temperature sensor. Specifically, the temperature-sensitive device can convert the temperature signal into a voltage signal and output it. That is, the temperature detection circuit 400 is used to receive the temperature of the chip and output a temperature coefficient voltage related to the chip temperature.

[0041] In embodiments of the present invention, the relationship between the PN junction voltage Vbe and its temperature is used to convert chip temperature into a temperature coefficient voltage. Specifically, the temperature detection circuit 400 includes at least one PN junction, and the relationship between the junction voltage Vbe, bias current, and temperature of this PN junction is as follows: Figure 4 As shown, specifically, when the PN junction is at absolute zero, the PN junction voltage Vbe is a fixed value; and the PN junction voltage is inversely proportional to the temperature, with its coefficient related to the bias current; the PN junction voltage has an exponential relationship with its bias current. Therefore, the PN junction voltage Vbe can be used as the output temperature coefficient voltage.

[0042] In some embodiments of the present invention, the temperature detection circuit 400 includes bipolar transistors Q1 and Q2. Specifically, the collector of bipolar transistor Q1 is coupled to the base and collector of bipolar transistor Q2 and grounded. The base of bipolar transistor Q1 is coupled to the emitter of bipolar transistor Q2. The PN junction between the base and emitter of bipolar transistors Q1 and Q2 serves as a temperature sensor. By using bipolar transistors Q1 and Q2, the temperature coefficient voltage output by the temperature detection circuit 400 is increased, making the output temperature coefficient voltage compatible with the reference voltage. For example, in some embodiments of the present invention, bipolar transistors Q1 and Q2 have the same specifications, and the output temperature coefficient voltage is twice the PN junction voltage Vbe. It should be understood that the temperature detection circuit of the present invention may also use only one or more bipolar transistors, adapted to other parts of the over-temperature protection circuit.

[0043] The bias current circuit 300 of the over-temperature protection circuit of the present invention adopts a current mirror structure to output a variable bias current, and the magnitude of the output bias current can be controlled by controlling the conducting branch.

[0044] In the over-temperature protection circuit of this invention, such as Figure 5 As shown, the bias current circuit 300 includes a current regulation module 310 and a current output module 320. The current regulation module 310 includes an input terminal C, with an external constant current source coupled to the input terminal C. Transistors T1 and T2 are connected in series to form a current mirror branch T1 / T2, and current mirror branches T11 / T12 are connected in series with the input terminal C, making the current of current mirror branches T11 / T12 a fixed reference value. Those skilled in the art should understand that the currents of current mirror branches T21 / T22, T31 / T32, T41 / T42, T51 / T52, T61 / T62, and T71 / T72 are proportional to the aforementioned reference current, and the proportionality coefficient is related to the transistors in each branch. The current regulation module 310 also includes a switching unit composed of multiple switching transistors, such as switching transistors M11-M15. This switching unit is coupled between the aforementioned current mirror branches T31 / T32-T71 / T72 and the adjustable current output port D of the current regulation module 310, and is used to control the conduction state of the branches containing current mirror branches T31 / T32-T71 / T72. This switching unit responds to external adjustment signals. It should be understood that the number and ratio of current mirror branches in the current regulation module 310 of the present invention can be arbitrarily set as needed. Correspondingly, the number of switching transistors in the switching unit is not limited, as long as they can control the on / off state of the current mirror branches. For example, when at least one of the aforementioned switching transistors M11-M15 is turned on, the corresponding branch outputs current to the adjustable current output port D. The current output by the adjustable current output port D is the sum of the current of the current mirror branches T21 / T22 and the current of the turned-on branch.

[0045] Similarly, the current output module 320 also employs a current mirror structure, specifically including current mirror branches T23 / T24, T81 / T82, and T91 / T92. Current mirror branch T23 / T24 is coupled to the adjustable current output port D, and its current is the output current of the adjustable current output port D. Current mirror branches T81 / T82 and T91 / T92 output bias current based on the current mirror structure positioned between the power supply voltage terminal and the adjustable current output terminals A and B. Specifically, adjustable current output terminal A is coupled to the base of the bipolar transistor Q1 and the emitter of Q2, and adjustable current output terminal B is coupled to the emitter of the bipolar transistor Q1. The bias current circuit 300 controls the bias current of the temperature detection circuit 400 through the adjustable current output terminals A and B. It should be understood that the number of adjustable current output terminals in the current output module 320 is the same as the number of bipolar transistors in the temperature detection circuit 400. In some embodiments of the present invention, the current mirror branches T23 / T24, T81 / T82 and T91 / T92 have the same specifications, and the output currents of output ports A and B are the same.

[0046] In embodiments of the present invention, the number of branches and the current ratio in the current regulation module 310 can be adjusted according to actual needs. For example, at the same temperature, the PN junction voltage and bias current have an exponential relationship. In order to achieve linear modulation of the temperature coefficient voltage output by the temperature detection circuit 400, in some embodiments, the current ratio of the current mirror branches T21 / T22, T31 / T32, T41 / T42, T51 / T52, T61 / T62, and T71 / T72 is 2:1:1:2:2:5. It should be understood that several current mirror branches of the same specification can also be used, and the above effect can also be achieved by controlling different numbers of conducting branches. In addition, the above-mentioned switching transistors can be bipolar transistors or MOSFETs, and the arrangement can be that multiple transistors are coupled at one end and the other end is coupled to the corresponding current mirror branch, or as shown in the figure. Figure 5 The hierarchical connection is shown.

[0047] The reference voltage circuit 200 of the over-temperature protection circuit of the present invention adopts a feedback regulation method to realize the switching of the reference voltage output. That is, the reference voltage circuit 200 receives the output signal of the signal generation circuit 100, and when the above output signal is reversed, the reference voltage output by the reference voltage circuit 200 is switched.

[0048] In the over-temperature protection circuit of the present invention, the reference voltage circuit 200 includes two switching transistors M1 and M2 and an output terminal 210. The switching states of the switching transistors M1 and M2 are used to control the reference voltage output by the output terminal 210. Specifically, both switching transistors M1 and M2 include an input terminal, an output terminal, and a control terminal. The two output terminals are coupled to the output terminal 210, and the input terminals provide a first reference voltage V1 and a second reference voltage V2 to the corresponding output terminals, respectively. The two control terminals otp1 and otp2 control the conduction between the corresponding input terminals and the output terminals. It should be understood that the over-temperature protection circuit of the present invention adopts a feedback regulation method. The output state of the reference circuit providing the circuit 200 is controlled by the control signal output by the signal generation circuit 100. That is, the aforementioned control terminals otp1 and otp2 are both coupled to different output terminals of the signal generation circuit 100.

[0049] In some embodiments of the present invention, the switching transistors M1 and M2 are MOSFETs, the output signal of the signal generation circuit 100 is a level signal, and the MOSFETs are voltage-controlled elements that do not consume power, reduce heat generation, and improve performance. Those skilled in the art should understand that the switching transistors M1 and M2 of the reference voltage circuit 200 can also be bipolar transistors or other devices that can be used as switching transistors.

[0050] The signal generation circuit 100 of the over-temperature protection circuit of the present invention determines whether the chip temperature has reached a predetermined value by comparing the temperature coefficient voltage with the reference voltage, and outputs a signal according to the comparison result to control the working state of the chip.

[0051] In the over-temperature protection circuit of the present invention, the signal generation circuit 100 includes a voltage comparator 110 and two NOT gates U1 and U2. The two input terminals of the voltage comparator 110 are respectively coupled to the output terminal 210 of the reference voltage circuit 200 and the emitter of the bipolar transistor Q1, and are used to compare the magnitude of the PN junction voltage Vbe output by the temperature detection circuit 400 with the reference voltage output by the reference voltage circuit 200. The two NOT gates U1 and U2 are coupled to the output terminal of the voltage comparator 110, and the output terminals of the NOT gates U1 and U2 are respectively coupled to the control terminals otp1 and otp2 of the switching transistors M1 and M2. It should be understood that the signals output by the output terminals of the NOT gates U1 and U2 are opposite, that is, only one of the switching transistors M1 and M2 is in the on state.

[0052] In some embodiments of the present invention, the output terminal of the voltage comparator 110 in the signal generation circuit 100 is coupled to only one NOT gate. Those skilled in the art should understand that in the above embodiments, two NOT gates U1 and U2 are provided for signal shaping and improving driving capability. When only one NOT gate is provided, the output terminal of the NOT gate and the output terminal of the voltage comparator 110 are respectively coupled to the control terminals of the two switching transistors.

[0053] When the chip is in operation, its temperature gradually increases over time. At this point, the chip temperature is below the first preset temperature T1. In the reference voltage circuit 200, switching transistor M1 is turned on, and M2 is turned off, outputting the first reference voltage V1. The temperature coefficient voltage output by the temperature detection circuit 400 is greater than the first reference voltage V1. At this time, the signal output by the signal generation circuit 100 controls the chip to continue operating.

[0054] The temperature coefficient voltage output by the temperature detection circuit 400 gradually decreases as the chip temperature rises. When the chip temperature rises above the first preset temperature T1, the temperature coefficient voltage is less than the first reference voltage V1. At this time, the relationship between the input voltages at the two input terminals of the voltage comparator 110 changes, the output signal of the signal generation circuit 100 flips, and the control chip stops working. At the same time, the signals received by the control terminals otp1 and otp2 of the switching transistors M1 and M2 in the reference voltage circuit 200 flip, M1 turns off, and M2 turns on, causing the output terminal 210 to output the second reference voltage V2. It should be understood that the second reference voltage V2 is greater than the first reference voltage V1.

[0055] When the chip is in a non-operating state, its temperature gradually decreases as heat is dissipated. At this time, the chip temperature is greater than the second preset temperature T2 (obviously, T1 is greater than T2), therefore, the temperature coefficient voltage output by the temperature detection circuit 400 is less than the second reference voltage V2. At this time, the chip is considered to be in an unsafe temperature, and the signal output by the signal generation circuit 100 controls the chip to be in a turned-off state.

[0056] The temperature coefficient voltage output by the temperature detection circuit 400 gradually increases as the chip temperature decreases. When the chip temperature drops below the second preset temperature T2, the temperature coefficient voltage becomes greater than the second reference voltage V2. The voltage comparator 110 reverses again, and the output signal controls the chip to start working again. At the same time, the switching states of the switching transistors M1 and M2 are switched, controlling the reference voltage circuit 200 to output the first reference voltage V1. That is, when the chip temperature drops to T2, the chip re-enters the working state.

[0057] In summary, the over-temperature protection circuit of the present invention can keep the chip temperature between a first preset temperature T1 and a second preset temperature T2.

[0058] The over-temperature protection circuit of this invention includes a bias current circuit 300 for adjusting the junction voltage Vbe of the temperature detection circuit 400. It should be understood that the magnitude of the PN junction voltage is exponentially related to the bias current of the PN junction; therefore, adjusting the magnitude of the bias current generated by the bias current circuit 300 can adjust the magnitude of the junction voltage Vbe. For example, the bias current circuit 300 is used to adjust the performance of the over-temperature protection circuit during testing.

[0059] It should be understood that for existing over-temperature protection circuits to operate, even if their output signal is reversed, their temperature should be between a first preset temperature T1 and a second preset temperature T2. Typically, both T1 and T2 are above 100 degrees Celsius. This means that existing over-temperature protection circuit tests require a high-temperature environment, such as a high-temperature chamber. This not only increases the testing difficulty but also introduces significant errors, causing a deviation between the actual temperature range of the chip and the expected value, potentially leading to safety hazards. To address this issue, the over-temperature protection circuit of this invention adds a bias current circuit 300 to enable testing of the over-temperature protection circuit at room temperature.

[0060] like Figure 4 As shown, the junction voltage Vbe is inversely proportional to temperature, and when the PN junction is at absolute zero (0K), its junction voltage is a fixed value, unaffected by the bias current. In other words, by adjusting the bias current at any temperature, the junction voltage can be adjusted at all temperatures. Specifically, adjusting the junction voltage at room temperature controls its value at high temperatures.

[0061] In some embodiments of the present invention, a high-temperature environment is not required during the testing of the over-temperature protection circuit, thereby improving the accuracy of the test. Specifically, the over-temperature protection circuit is placed in a normal temperature environment (27°C) and the temperature coefficient voltage output by the temperature detection circuit 400 is measured. Those skilled in the art should understand that the aforementioned first reference voltage V1 and second reference voltage V2 are both provided by external circuits and are fixed values. The first preset temperature T1 and the second preset temperature T2 are also determined by the chip itself. The junction voltage of the PN junction has a linear relationship with temperature. That is to say, in addition to the fixed voltage value corresponding to absolute zero, the voltage-temperature relationship of the PN junction also includes at least one fixed point, namely, the junction voltage value V corresponding to normal temperature (27°C) is calculable. By adjusting the bias current to the calculated value V, the over-temperature protection circuit can be ensured to operate within the preset temperature range. This not only reduces the testing difficulty but also improves the working accuracy of the over-temperature protection circuit.

[0062] In some embodiments of the present invention, since the junction voltage of the PN junction is exponentially related to the bias current, the bias current changes nonlinearly during the adjustment of the junction voltage, thereby making the junction voltage change linearly to reduce errors.

[0063] The present invention also provides an integrated circuit chip and a signal processing device. The over-temperature protection circuit is disposed in the integrated circuit chip, and the integrated circuit chip includes external circuitry for providing an adjustment signal to the over-temperature protection circuit. The signal processing device includes the integrated circuit chip. Specifically, the signal processing device can be any one of a smart TV, smartphone, smartwatch, tablet computer, computer, laptop computer, all-in-one computer, industrial computer, server, financial trading device, or vehicle computer.

[0064] It should be noted that those skilled in the art will understand that the terms "during," "when," and "when…" used herein in relation to circuit operation are not strict terms indicating an action that occurs immediately upon the commencement of a startup action, but rather that there may be one or more small but reasonable delays, such as various transmission delays, between the startup action and the reaction action initiated by it. The terms "approximately" or "substantially" used herein mean that an element value is expected to be close to the declared value or position. However, as is well known in the art, there are always small deviations that make it difficult for the value or position to be strictly the declared value.

[0065] As described above, these embodiments of the present invention do not exhaustively describe all details, nor do they limit the invention to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The scope of protection of this invention should be determined by the scope defined in the claims and their equivalents.

Claims

1. An over-temperature protection circuit, characterized in that, include: The signal generation circuit outputs a control signal based on the comparison result between the temperature coefficient voltage and the reference voltage characterizing the set temperature, wherein the set temperature includes a first set temperature and a second set temperature lower than the first set temperature. A reference voltage circuit, coupled to the signal generation circuit, is used to provide one of a first reference voltage and a second reference voltage as the reference voltage according to the control signal, wherein the first reference voltage represents the first set temperature and the second reference voltage represents the second set temperature. A temperature detection circuit, coupled to the signal generation circuit, is used to provide the temperature coefficient voltage in response to the ambient temperature; as well as A bias current circuit, coupled to the temperature detection circuit, is used to provide an adjustable bias current. During the testing and calibration phase of the over-temperature protection circuit, the temperature coefficient voltage is adjusted by regulating the bias current. When the control signal indicates that the temperature coefficient voltage is higher than the reference voltage, the reference voltage circuit selects the first reference voltage as the reference voltage. When the control signal indicates that the temperature coefficient voltage is lower than the reference voltage, the reference voltage circuit selects the second reference voltage as the reference voltage.

2. The over-temperature protection circuit according to claim 1, characterized in that, The bias current circuit generates the bias current according to the adjustment signal, which is determined based on the temperature coefficient voltage under the test environment, including the normal temperature environment.

3. The over-temperature protection circuit according to claim 2, characterized in that, The bias current circuit includes: A current regulation module generates an adjustable current based on a reference current, wherein the ratio between the adjustable current and the reference current is controlled by an adjustment signal; and A current output module, coupled to the current regulation module, outputs the bias current according to the adjustable current.

4. The over-temperature protection circuit according to claim 3, characterized in that, The current regulation module includes: Multiple current mirror branches, each providing a branch current proportional to the reference current, are connected in parallel between the reference ground and the adjustable current output terminal to provide the adjustable current; and A switching unit is disposed between at least one of the current mirror branches and the adjustable current output terminal. The switching unit controls the conduction and cutoff of the at least one current mirror branch under the control of the adjustment signal.

5. The over-temperature protection circuit according to claim 4, characterized in that, The switching unit includes at least one switching transistor, which is connected between each of the at least one current mirror branch and the adjustable current output terminal. The control terminal of each switching transistor is controlled by the corresponding data bit in the adjustment signal.

6. The over-temperature protection circuit according to claim 4, characterized in that, The plurality of current mirror branches respectively provide branch currents that are proportional to or proportional to the reference current.

7. The over-temperature protection circuit according to claim 4, characterized in that, The current output module provides the bias current based on a current mirror structure disposed between the power supply voltage terminal and the adjustable current output terminal.

8. The over-temperature protection circuit according to claim 1, characterized in that, The temperature detection circuit includes a first bipolar transistor, the base and collector of the first bipolar transistor are shorted and grounded, the emitter of the first bipolar transistor provides the temperature coefficient voltage and receives the bias current, the bias current is used to configure the PN junction voltage formed between the emitter and the base so that the temperature coefficient voltage is less than the reference voltage in an environment higher than the set temperature.

9. The over-temperature protection circuit according to claim 1, characterized in that, The bias current includes bias currents from the 1st to the Nth, and the temperature detection circuit includes bipolar transistors from the 1st to the Nth, where N is a natural number greater than 1. The emitter of the first bipolar transistor provides the temperature coefficient voltage and receives the first bias current. The emitter of the i-th bipolar transistor is connected to the base of the (i-1)-th bipolar transistor and receives the i-th bias current. The base of the N-th bipolar transistor is grounded to the collectors of the first to N-th bipolar transistors. i is a natural number greater than or equal to 2 and less than or equal to N.

10. The over-temperature protection circuit according to claim 1, characterized in that, The reference voltage circuit includes a first switching transistor and a second switching transistor. The control terminals of the first switch and the second switch are respectively controlled by the control signal and the inverted signal of the control signal. The first current terminals of the first switch and the second switch respectively receive the first reference voltage and the second reference voltage. The second current terminals of the first switch and the second switch are connected and provide the reference voltage.

11. A test method for an over-temperature protection circuit, wherein the over-temperature protection circuit comprises the over-temperature protection circuit as described in any one of claims 1-10, and the temperature detection circuit provides the temperature coefficient voltage based on the PN junction voltage provided by the bipolar transistor in response to ambient temperature, characterized in that... The testing method includes: The first measured value of the PN junction voltage was obtained under test conditions; Based on the expected curve of the PN junction voltage changing with temperature, determine the bias current used to adjust the temperature coefficient voltage so that the first measured value meets the expected curve. The expected curve is determined based on the fixed value of the PN junction voltage at absolute zero and the expected value of the PN junction voltage at the set temperature, wherein the temperature of the test environment is lower than the set temperature.

12. The test method according to claim 11, wherein, On the expected curve, the fixed value, the first measured value, and the expected value have a linear relationship with temperature.

13. An integrated circuit chip, characterized in that, include: The over-temperature protection circuit according to any one of claims 1-10; An external circuit that outputs an adjustment signal to the bias current circuit.

14. A signal processing apparatus, characterized in that, Including the integrated circuit chip as described in claim 13.

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