TWI636269B - Over-temperature detection circuit and testing method thereof - Google Patents

Abstract

An over temperature detecting circuit and a testing method thereof. The test method of the over temperature detecting circuit includes the following steps. Providing a test current to the first circuit of the over temperature detecting circuit at the first temperature through the test circuit. A first voltage is generated by the first circuit reacting to the test current. The comparison voltage through the temperature detecting circuit compares the first voltage with the second voltage to obtain a comparison result. The test circuit determines whether to adjust the test current according to the comparison result. The over temperature detection point of the temperature detection circuit is estimated by the test circuit according to the comparison result and the test current, wherein the first temperature is not equal to the over temperature detection point.

Description

Over temperature detection circuit and test method thereof

The invention relates to a detection circuit, and in particular to an over temperature detection circuit and a test method thereof.

The integrated circuit component of the electronic device usually has an over temperature protection circuit, wherein the over temperature protection circuit can activate the protection mechanism when the temperature of the electronic device or the integrated circuit component reaches the temperature detection point to avoid the electronic device or the integrated circuit component. Damaged or even dangerous due to excessive temperature. It can be seen that the over-temperature protection circuit can work normally.

In general, the over-temperature detection point of the over-temperature protection circuit is usually very high (for example, the over-temperature detection point of the vehicle regulator is usually designed at about 175 °C). If the over-temperature protection circuit is to be functionally tested, it is bound to be It is necessary to use a high temperature test method to test whether the over temperature detection point is within the designed temperature range. However, the probe card that is required to test the integrated circuit components may not be able to bear. Extremely high temperatures make high temperature testing difficult. In addition, if the over-temperature protection circuit in the integrated circuit component is subjected to high-temperature test, it is inevitable that the integrated circuit component is heated and maintained at a specific temperature before the test can be performed, so that the test method will increase the overall Test cost and test time. Therefore, how to reduce the test difficulty, test cost and test time of the over temperature protection circuit is one of the major issues faced by those skilled in the art.

In view of this, the present invention provides an over temperature detecting circuit and a testing method thereof, which can test the function of the temperature detecting circuit at normal temperature to reduce the test difficulty, test cost and test time of the over temperature detecting circuit.

The over temperature detecting circuit of the present invention includes a first circuit, a comparison circuit, and a test circuit. The first circuit is responsive to ambient temperature to generate a first voltage. The comparison circuit is coupled to the first circuit to receive the first voltage, and compares the first voltage with the second voltage to generate a comparison result, and accordingly indicates whether the ambient temperature reaches the over temperature detection point. The test circuit is coupled to the comparison circuit to receive the comparison result, and provides the test current to the first circuit in the test mode. The test circuit determines whether to adjust the test current according to the comparison result when the ambient temperature is the first temperature, so that the first circuit changes the first voltage in response to the change of the test current. The test circuit estimates the temperature detection point according to the comparison result and the test current at the first temperature, wherein the first temperature is not equal to the over temperature detection point.

The test method of the over temperature detecting circuit of the present invention includes the following steps. through The test circuit provides a test current to the first circuit of the over temperature detecting circuit at the first temperature. A first voltage is generated by the first circuit reacting to the test current. The comparison voltage through the temperature detecting circuit compares the first voltage with the second voltage to obtain a comparison result. The test circuit determines whether to adjust the test current according to the comparison result. The over temperature detection point of the temperature detection circuit is estimated by the test circuit according to the comparison result and the test current, wherein the first temperature is not equal to the over temperature detection point.

Based on the above, the over temperature detecting circuit and the testing method thereof according to the present invention can estimate the over temperature detecting point of the over temperature detecting circuit at a first temperature (for example, normal temperature). Therefore, the over temperature detecting circuit and the testing method thereof according to the embodiments of the present invention can effectively reduce over temperature detection, compared with the testing method for measuring the over temperature detecting point by placing the over temperature detecting circuit in a high temperature environment. Test circuit test difficulty, test cost and test time.

The above described features and advantages of the invention will be apparent from the following description.

100,200‧‧‧Over temperature detection circuit

110‧‧‧First circuit

120‧‧‧second circuit

130‧‧‧Comparative circuit

140‧‧‧Bias circuit

150‧‧‧Test circuit

A, B‧‧ points

CRST‧‧‧ comparison results

Ibias‧‧‧ bias current

Ir1‧‧‧ first reference current value

Ir2‧‧‧ second reference current value

IRST‧‧‧Results

Itst‧‧‧ test current

L1, L1’, L2‧‧‧ segments

OT‧‧‧Over temperature detection point

Q11, Q12, Q13‧‧‧ first transistor

Q21, Q22, Q23, Q24‧‧‧second transistor

S400, S410, S420, S430, S440, S531, S532, S533, S534, S535, S641, S642, S643‧‧‧ steps of the test method

T1‧‧‧ first temperature

TRST‧‧‧ test results

V1‧‧‧ first voltage

V2‧‧‧second voltage

The following drawings are a part of the specification of the invention, and illustrate the embodiments of the invention

FIG. 1 is a block diagram of an over temperature detecting circuit according to an embodiment of the invention.

2 is a schematic diagram of an over temperature detecting circuit according to another embodiment of the invention. Block diagram.

3 is a schematic diagram showing the relationship between the first voltage and the second voltage of FIG. 2 and ambient temperature.

4 is a flow chart showing the steps of a test method according to an embodiment of the invention.

FIG. 5 is a flow chart showing the detailed steps of step S430 of FIG. 4 according to an embodiment of the invention.

FIG. 6 is a flow chart showing the detailed steps of step S440 of FIG. 4 according to an embodiment of the invention.

In order to make the content of the present invention easier to understand, the following specific embodiments are examples of the invention that can be implemented. In addition, wherever possible, the same reference numerals in the FIGS.

Please refer to FIG. 1 . FIG. 1 is a block diagram of an over temperature detecting circuit according to an embodiment of the invention. The over temperature detecting circuit 100 can include the first circuit 110, the comparison circuit 130, and the test circuit 150, but the invention is not limited thereto. The first circuit 110 is configured to generate a first voltage V1 in response to an ambient temperature. The comparison circuit 130 is coupled to the first circuit 110 to receive the first voltage V1, and compares the first voltage V1 with the second voltage V2 to generate a comparison result CRST, and according to whether the ambient temperature reaches the over temperature detection point OT, The external circuit can determine whether the temperature protection mechanism is activated according to the comparison result CRST. In an embodiment of the invention, the second voltage V2 can be, for example, a fixed voltage (ie, a zero temperature coefficient) or a negative temperature coefficient. Voltage or positive temperature coefficient voltage, depending on the actual application or design requirements.

The test circuit 150 is coupled to the comparison circuit 130 to receive the comparison result CRST, and in the test mode, the test current Itst can be provided to the first circuit 110 to estimate the temperature detection point OT. Further, the test circuit 150 can determine whether to adjust the test current Itst according to the comparison result CRST when the ambient temperature is the first temperature, and the first circuit 110 can change the first voltage V1 in response to the change of the test current Itst. In addition, the test circuit 150 can estimate the temperature detection point OT according to the comparison result CRST and the test current Itst at the first temperature, wherein the first temperature is not equal to the over temperature detection point OT. In an embodiment of the invention, the first temperature may be, for example, normal temperature or room temperature, but the invention is not limited thereto. Since the test circuit 150 can estimate the over temperature detection point OT of the over temperature detecting circuit 100 at the first temperature (for example, normal temperature or room temperature), it is not necessary to place the over temperature detecting circuit 100 in a high temperature environment for measurement. The over temperature detection point OT can effectively reduce the test difficulty, test cost and test time of the over temperature detection circuit 100.

Please refer to FIG. 2, which is a schematic diagram of an over temperature detecting circuit according to another embodiment of the invention. The temperature detecting circuit 200 may include the first circuit 110, the second circuit 120, the comparison circuit 130, the bias circuit 140, and the test circuit 150, but the present invention is not limited thereto. The first circuit 110, the comparison circuit 130, and the test circuit 150 of FIG. 2 are similar to the first circuit 110, the comparison circuit 130, and the test circuit 150 of FIG. 1, respectively, so that the operation thereof can refer to the related description of FIG. 1 above, and no longer Narration.

The second circuit 120 is coupled to the comparison circuit 130. The second circuit 120 can react to The ambient temperature produces a second voltage V2. The bias circuit 140 is coupled to the first circuit 110 and the second circuit 120. The bias circuit 140 is configured to provide a bias current Ibias required for the operation of the first circuit 110 and the second circuit 120.

In an embodiment of the invention, the first circuit 110 may include X first transistors, each of the X first transistors may be a bipolar junction transistor (BJT). Where X is a positive integer, but the invention is not limited thereto. However, for convenience of explanation, in the embodiment, X is equal to 3 as an example, and an embodiment in which X is another positive integer can be analogized according to the following description. Therefore, as shown in FIG. 2, the first circuit 110 includes three first transistors Q11~Q13, wherein the first transistors Q11~Q13 are serially connected in series, and are serially connected to the ground GND and the bias circuit 140. between. In detail, the emitter end of the first transistor Q11 (which is the first-stage first transistor) is coupled to the ground GND. The base terminal of the first transistor Q11 is coupled to the collector terminal and coupled to the emitter terminal of the first transistor Q12 (which is the second-stage first transistor). The base terminal of the first transistor Q12 is coupled to the collector terminal and coupled to the emitter terminal of the first transistor Q13 (which is the last stage first transistor). The base terminal of the first transistor Q13 is coupled to the collector terminal and coupled to the bias circuit 140 and the test circuit 150 to receive the bias current Ibias and the test current Itst.

In an embodiment of the invention, the second circuit 120 may include Y second transistors, each of the Y second transistors may be a bipolar junction transistor, where Y is a positive integer, but The invention is not limited thereto. However, for convenience of explanation, in the present embodiment, Y is equal to 4 as an example, and an embodiment in which Y is another positive integer can be analogized according to the following description. Therefore, as shown in Figure 2, the second electricity The circuit 120 includes four second transistors Q21~Q24, wherein the second transistors Q21~Q24 are serially connected in series, and are connected in series between the ground GND and the bias circuit 140. In detail, the emitter end of the second transistor Q21 (which is the first-stage second transistor) is coupled to the ground GND. The base terminal of the second transistor Q21 is coupled to the collector terminal and coupled to the emitter terminal of the second transistor Q22 (which is the second-stage second transistor). The base terminal of the second transistor Q22 is coupled to the collector terminal and coupled to the emitter terminal of the second transistor Q23 (which is the third-stage second transistor). The base terminal of the second transistor Q23 is coupled to the collector terminal and coupled to the emitter terminal of the second transistor Q24 (which is the last stage of the second transistor). The base terminal of the second transistor Q24 is coupled to the collector terminal and coupled to the bias circuit 140 to receive the bias current Ibias.

In an embodiment of the present invention, the sizes of the first transistors Q11 to Q13 shown in FIG. 2 may be the same as each other or different from each other depending on actual application or design requirements. In an embodiment of the present invention, the sizes of the second transistors Q21 to Q24 shown in FIG. 2 may be the same as each other or different from each other depending on actual application or design requirements.

In an embodiment of the present invention, the first transistor Q11~Q13 and the second transistor Q21~Q24 shown in FIG. 2 may also be a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). This is achieved, but the invention is not limited thereto.

In an embodiment of the present invention, the first transistors Q11~Q13 and the second transistors Q21~Q24 shown in FIG. 2 may also be replaced by diodes, but the invention is not limited thereto. .

In an embodiment of the invention, the bias circuit 140 can be powered by a current source. The road is implemented, but the invention is not limited thereto.

In an embodiment of the invention, the test circuit 150 can be a hardware, a firmware, or a software or machine executable code stored in a memory and loaded by a microprocessor or a microcontroller. If implemented by hardware, the test circuit 150 may be implemented by a single integrated circuit chip or by multiple circuit chips, but the invention is not limited thereto. The plurality of circuit chips or the single integrated circuit chip may be implemented by using a special function integrated circuit (ASIC) or a programmable logic gate array (FPGA). The above memory may be, for example, a random access memory, a read only memory, or a flash memory.

The test of the over temperature detecting circuit 200 will be described below. For convenience of explanation, it is assumed that the sizes of the first transistors Q11 to Q13 are the same, the sizes of the second transistors Q21 to Q24 are the same, and the emitter area of each of the second transistors Q21 to Q24 is the first power. M times the emitter area of each of the crystals Q11 to Q13, where M is a positive number. Referring to FIG. 2 and FIG. 3 together, FIG. 3 is a schematic diagram showing the relationship between the first voltage V1 and the second voltage V2 of FIG. 2 and the ambient temperature, wherein the line segment L1 is the relationship between the first voltage V1 and the ambient temperature in the normal mode, and the line segment L2 is the relationship between the second voltage V2 in the normal mode or the test mode and the ambient temperature, and the line segment L1' is the relationship between the first voltage V1 obtained after adjusting the test current Itst in the test mode and the ambient temperature.

In detail, according to FIG. 2, the first voltage V1 may be based on the base-emitter voltage VBE1 of each of the first transistors Q11-Q13 and the number of the first transistors Q11-Q13. X determines, that is, V1 = X × VBE1. Since the base-emitter voltage VBE1 is a voltage of a negative temperature coefficient, the first voltage V1 is also a voltage of a negative temperature coefficient as shown by the line segment L1 (or line segment L1') of FIG. In addition, according to the current-voltage formula of the bipolar junction transistor in the active mode, the first voltage V1 as shown in the formula (1) can be obtained, wherein NF is a forward mode ideality factor, VT For thermal voltage, IS is the saturation current of the first transistor Q11~Q13, and N is the ratio of the sum of the test current Itst and the bias current Ibias to the bias current Ibias.

Similarly, the second voltage V2 can be determined according to the base-emitter voltage VBE2 of each of the second transistors Q21 to Q24 and the number of the second transistors Q21 to Q24, that is, V2=Y×VBE2. Since the base-emitter voltage VBE2 is a voltage of a negative temperature coefficient, the second voltage V2 is also a voltage of a negative temperature coefficient, as shown by the line segment L2 of FIG. In addition, the second voltage V2 as shown in the equation (2) can be obtained from the current-voltage formula of the bipolar junction transistor in the active mode. By subtracting the equation (2) from the equation (1), the voltage difference Vd between the second voltage V2 and the first voltage V1 is obtained, as shown in the equation (3). The temperature coefficient Δ Vd of the voltage difference Vd can be calculated according to the equation (4), where Tk is the absolute temperature.

In detail, in the normal mode, the test circuit 150 is disabled (that is, the test current Itst is 0 or the ratio N is 1), when the ambient temperature rises to be greater than or equal to the over temperature detection point OT, the second The voltage V2 is less than or equal to the first voltage V1, causing the output of the comparison circuit 120 (ie, the comparison result CRST) to transition (eg, from a logic 0 to a logic 1), as shown at point A of FIG.

In contrast, in test mode, test circuit 150 is enabled. In order to estimate the over temperature detection point OT at the first temperature T1, the test circuit 150 can cause the first circuit 110 to react to the change of the test current Itst by providing and adjusting the test current Itst (ie, the adjustment ratio N). And outputting the changed first voltage V1 (as shown by the line segment L1' of FIG. 3), causing the second voltage V2 to be less than or equal to the changed first voltage V1 at the first temperature T1, as shown by point B in FIG. Show. The test circuit 150 can then estimate the temperature detection point OT according to the magnitude of the test current Itst.

For example, assume that the forward mode ideal factor NF is 1.06, the bias current Ibias is 4 microamperes (uA), the number Y is 4, the number X is 3, the ratio M is 4, and the saturation current IS is 0.6 fly amps. (fA), and the thermal voltage VT is 23.55 millivolts (mV) at a temperature of 0 °C. In the normal mode (that is, the ratio N is 1), the ratio N is 1 and the above parameters are substituted into equations (3) and (4), respectively, and the voltage difference Vd at a resolution of 0 ° C can be obtained, respectively. 0.426V and the temperature coefficient △ Vd about -2.43mV / ℃. Therefore, in the normal mode, the temperature at which the voltage difference Vd falls to 0V is about 175 ° C (that is, 0.426 V ÷ 2.43 mV / ° C ≒ 175 ° C), in other words, the over temperature detection point of the over temperature detecting circuit 200 The OT is about 175 °C.

On the other hand, in the test mode, when the test current Itst is adjusted so that the ratio N is 80, the ratio N is 80 and the above parameters are substituted into the equations (3) and (4), respectively. The voltage difference Vd at a resolution of 0 ° C is about 0.098 V and the temperature coefficient Δ Vd is about -3.63 mV / ° C, so the temperature at which the voltage difference Vd falls to 0 V is about 27 ° C (that is, 0.098 V ÷ 3.63 mV / °C≒27°C). Therefore, in the case where the ambient temperature is 27 ° C, the ratio N in the test mode is 80 corresponding to the over temperature detection point OT in the normal mode is 175 ° C.

It can be seen that the designer can test the over temperature detecting circuit with different over temperature detecting points OT in advance at an ambient temperature of 27 ° C to obtain a corresponding ratio N, and accordingly establish a lookup table. In this way, when the mass detection circuit 200 is mass-produced at an ambient temperature of 27 ° C, the test circuit 150 can calculate the ratio N according to the magnitude of the test current Itst, and find the corresponding in the above-mentioned lookup table. Over temperature detection point OT at ratio N.

2 to FIG. 4, FIG. 4 is a flow chart showing the steps of the test method according to an embodiment of the present invention, which can be used in the over temperature detection circuit 200 of FIG. 2 (or the over temperature detection of FIG. 1). Circuit 100). First, in step S400, the test current Itst can be supplied to the first circuit 110 through the test circuit 150 at the first temperature T1. Next, in step S410, the first voltage V1 is generated by the first circuit 110 reacting to the test current Itst. Then, in step S420, the first voltage V1 and the second voltage V2 are compared by the comparison circuit 130 to obtain a comparison result CRST. Next, in step S430, the test circuit 150 determines whether to adjust the test current Itst based on the comparison result CRST. Thereafter, in step S440, the over-temperature can be estimated by the test circuit 150 according to the comparison result CRST and the test current Itst. The over temperature detection point OT of the degree detection circuit 200.

The details of step S430 will be described below. As shown in FIG. 5, step S430 may include the following detailed steps. In step S531, it is determined whether the voltage difference Vd between the second voltage V2 and the first voltage V1 is less than or equal to zero according to the comparison result CRST. If the result of the determination in step S531 is negative, it is determined whether the test current Itst is greater than or equal to a critical current value, as shown in step S533. If the result of the determination in step S533 is YES, it indicates that the test current Itst can be provided by the test circuit 150 has reached the limit but the temperature detection point OT cannot be estimated, so the test result 150 can be output through the test circuit 150 to indicate the over temperature. The detecting circuit 200 is abnormal (that is, defective), as shown in step S534, and ends the test after step S534. In contrast, if the result of the determination in step S533 is NO, the test current Itst can be raised by a predetermined amplitude through the test circuit 150, as shown in step S535, and after the step S535 is completed, the process returns to the step S410.

In addition, if the result of the determination in step S531 is YES, the adjustment of the test current Itst is stopped, as shown in step S532, and after step S532, step S440 is performed, that is, the temperature detection is estimated based on the magnitude of the test current Itst at this time. Measuring point OT.

In an embodiment of the present invention, step S440 may include the following detailed steps: calculating a ratio N according to the magnitude of the test current Itst through the test circuit 150, and finding an over temperature detection point corresponding to the ratio N in the lookup table. OT, but the invention is not limited thereto.

In another embodiment of the present invention, the magnitude relationship between the test current Itst and the first reference current value Ir1 and the second reference current value Ir2 may also be estimated. Whether the temperature detection point OT is within a temperature range, thereby determining whether the temperature detecting circuit 200 is normal, wherein the temperature range can be set according to actual application or design requirements. In detail, as shown in FIG. 6, step S440 may include the following detailed steps. First, in step S641, it may be determined whether the test current Itst is greater than the second reference current value Ir2 and smaller than the first reference current value Ir1 to obtain the determination result IRST, wherein the first reference current value Ir1 is greater than the second reference current value Ir2, The first reference current value Ir1 corresponds to an upper limit temperature value of the above temperature range, and the second reference current value Ir2 corresponds to a lower limit temperature value of the above temperature range. If the result of the determination in step S641 is YES, it indicates that the over temperature detection point OT is in the above temperature range, so the test result 150 can be output through the test circuit 150 to indicate that the over temperature detection circuit 200 is normal (ie, good), such as Step S642 is shown, and the test is ended after step S642. In contrast, if the result of the determination in the step S641 is no, the temperature detection point OT is outside the above temperature range, so that the test result 150 is outputted by the test circuit 150 to indicate that the over temperature detection circuit 200 is abnormal (ie, The defective product is as shown in step S643, and the test is ended after step S643.

For example, during the test, it is assumed that the over temperature detection point OT of the over temperature detecting circuit 200 is between 170 ° C and 180 ° C and will be recognized as a good product, and below 170 ° C or higher than 180 ° C will be identified. It is a defective product in which the ratio N corresponding to 180 ° C (or the first reference current value Ir 1 ) is 40, and the ratio N corresponding to 170 ° C (or the second reference current value Ir 2 ) is 30. In the above case, if the ratio N corresponding to the test current Itst in step S440 is any one of 30 to 40, the test circuit 150 can determine that the over temperature detection point OT of the over temperature detecting circuit 200 is located at 170. °C to The temperature detecting circuit 200 is considered to be good at 180 °C. If the ratio N corresponding to the test current Itst in step S440 is not any one of 30 to 40, the test circuit 150 may determine that the over temperature detection point OT of the over temperature detecting circuit 200 is lower than 170 ° C or higher. The temperature detecting circuit 200 was determined to be defective at 180 °C.

It is worth mentioning that any one of the first transistors Q11~Q13 of FIG. 2 is short-circuited or broken, or any one of the second transistors Q21-Q24 is short-circuited or broken, which may cause The over temperature detection point OT of the over temperature detecting circuit 200 falls outside the above temperature range. Therefore, through the above test method of the present invention, it is not only possible to test whether the temperature detection point OT is too high or too low, and whether the first transistor Q11~Q13 or the second transistor Q21~Q24 is short-circuited or disconnected. .

In summary, the over temperature detecting circuit and the testing method thereof according to the embodiments of the present invention can estimate the over temperature detecting point of the over temperature detecting circuit under the first temperature (for example, normal temperature), and according to To test whether the function of the temperature detection circuit is normal. Therefore, the over temperature detecting circuit and the testing method thereof according to the embodiments of the present invention can effectively reduce over temperature detection, compared with the testing method for measuring the over temperature detecting point by placing the over temperature detecting circuit in a high temperature environment. Test circuit test difficulty, test cost and test time.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

Claims (13)

An over temperature detecting circuit includes: a first circuit for generating a first voltage in response to an ambient temperature; a comparing circuit coupled to the first circuit to receive the first voltage, and the first Comparing a voltage with a second voltage to generate a comparison result, and indicating whether the ambient temperature reaches an over temperature detection point; and a test circuit coupled to the comparison circuit to receive the comparison result, and testing Providing a test current to the first circuit, wherein the test circuit determines whether to adjust the test current according to the comparison result when the ambient temperature is a first temperature, so that the first circuit reacts to the change of the test current And changing the first voltage, and the test circuit estimates the over temperature detection point according to the comparison result and the test current at the first temperature, wherein the first temperature is not equal to the over temperature detection point. The over temperature detecting circuit according to claim 1, wherein in the test mode and the first temperature: when the comparison result indicates that a voltage difference between the second voltage and the first voltage is less than Or equal to zero, the test circuit stops adjusting the test current, and the test circuit estimates the over temperature detection point according to the test current. When the comparison result indicates that the voltage difference is greater than zero, the test circuit determines the test current. Whether the value is greater than or equal to a critical current value, if the test current is greater than or equal to the critical current value, the test circuit outputs a test result to indicate that the over temperature detection circuit is abnormal, and if the test current is less than the critical current value, The test circuit raises the test current by a predetermined amplitude. The over temperature detecting circuit of claim 2, wherein: when the comparison result indicates that the voltage difference is less than or equal to zero, the test circuit finds a temperature corresponding to the test current in a lookup table. The over temperature detection point is obtained by the value. The over temperature detecting circuit according to claim 1, wherein in the test mode and the first temperature: when the comparison result indicates that a voltage difference between the second voltage and the first voltage is less than Or equal to zero, the test circuit estimates whether the over temperature detection point is within a temperature range and determines the over temperature detection according to the magnitude relationship between the test current and a first reference current value and a second reference current value. Check if the circuit is normal. The over temperature detecting circuit of claim 4, wherein: the test circuit determines whether the test current is greater than the second reference current value and less than the first reference current value to obtain a determination result, wherein the The first reference current value is greater than the second reference current value, the first reference current value corresponds to an upper limit temperature value of the temperature range, and the second reference current value corresponds to a lower limit temperature value of the temperature range, if If the determination result is yes, the test circuit determines that the over temperature detection point is within the temperature range, and outputs a test result to indicate that the over temperature detection circuit is normal; and if the determination result is no, the test circuit determines the The over temperature detection point is outside the temperature range, and the test result is output to indicate that the over temperature detection circuit is abnormal. The over temperature detecting circuit of claim 1, further comprising: a second circuit coupled to the comparison circuit for generating the second voltage in response to the ambient temperature; and a bias circuit The first circuit and the second circuit are coupled to provide a bias current required for the first circuit and the second circuit to operate. The over temperature detecting circuit of claim 6, wherein: the first circuit comprises X first transistors, each of the X first transistors being a bipolar junction transistor, The X first transistors are serially connected in series, and are connected in series between a ground terminal and the bias circuit, wherein the emitter poles of the first stage first transistors in the X first transistors are coupled The ground terminal, the base end of each of the first transistors of the X first transistors except the last stage first transistor is coupled to the collector terminal and coupled to the emitter end of the first transistor of the next stage And a base terminal of the last stage first transistor of the X first transistors is coupled to the collector terminal and coupled to the bias circuit and the test circuit, wherein X is a positive integer; and the first The two circuits include Y second transistors, each of the Y second transistors being a bi-carrier junction transistor, the Y second transistors being serially connected in series, and serially connected to the ground terminal Between the bias circuits, wherein an emitter end of the first stage second transistor of the Y second transistors is coupled to the ground end, the Y first The base end of each stage of the second transistor except the last stage second transistor is coupled to the collector terminal and coupled to the emitter end of the next stage second transistor, and the Y second transistors The base terminal of the second transistor of the last stage is coupled to the collector terminal and coupled to the bias circuit, wherein Y is a positive integer. The over temperature detecting circuit of claim 7, wherein: the voltage difference between the second voltage and the first voltage is determined according to the following formula: , Where Vd is the voltage difference, NF is the forward mode ideal factor, VT is the thermal voltage, Ibias is the bias current, IS is the saturation current of the first transistor, and M is the emitter of the second transistor The ratio of the area to the emitter area of the first transistor, N is the ratio of the sum of the test current to the bias current and the bias current. A method for testing an over temperature detecting circuit includes: providing a test current to a first circuit of the over temperature detecting circuit at a first temperature through a test circuit; reacting the test current through the first circuit Generating a first voltage; comparing the first voltage with a second voltage through a comparison circuit of the over temperature detecting circuit to obtain a comparison result; determining, by the testing circuit, whether to adjust the test current according to the comparison result; And estimating, by the test circuit, an over temperature detection point of the over temperature detection circuit according to the comparison result and the test current, wherein the first temperature is not equal to the over temperature detection point. The test method of claim 9, wherein the step of determining, by the test circuit, whether to adjust the test current according to the comparison result comprises: when the comparison result indicates the second voltage and the first voltage When a voltage difference is less than or equal to zero, the adjustment of the test current is stopped; when the comparison result indicates that the voltage difference is greater than zero, it is determined whether the test current is greater than or equal to a critical current value; if the test current is greater than or equal to the The critical current value indicates that the over temperature detecting circuit is abnormal; and if the test current is less than the critical current value, the test current is raised by a predetermined amplitude. The test method of claim 9, wherein the step of estimating the over temperature detection point based on the comparison result and the test current comprises: when the comparison result indicates the second voltage and the first When a voltage difference between the voltages is less than or equal to zero, the over-temperature detection point is obtained by finding a temperature value corresponding to the test current in a look-up table through the test circuit. The test method of claim 9, wherein the step of estimating the over temperature detection point based on the comparison result and the test current comprises: when the comparison result indicates the second voltage and the first When a voltage difference between the voltages is less than or equal to zero, the test circuit estimates whether the over temperature detection point is located according to the magnitude relationship between the test current and a first reference current value and a second reference current value. Within a temperature range and determining whether the over temperature detection circuit is normal. The test method of claim 12, wherein the estimating whether the over temperature detection point is located according to the magnitude relationship between the test current and the first reference current value and the second reference current value The step of determining whether the over temperature detecting circuit is normal or not includes: determining, by the testing circuit, whether the test current is greater than the second reference current value and less than the first reference current value, to obtain a determination result, where The first reference current value is greater than the second reference current value, the first reference current value corresponds to an upper limit temperature value of the temperature range, and the second reference current value corresponds to a lower limit temperature value of the temperature range; The determination result is yes, the over temperature detection point is located in the temperature range, and the over temperature detection circuit is normal through the test circuit; and if the determination result is no, the over temperature detection point is located in the temperature range In addition, the test circuit indicates that the over temperature detection circuit is abnormal.