Temperature detection device

Abstract

The subject of the present invention is to improve the temperature detection accuracy. The temperature detection device (1-1) has a temperature detection diode (Dt), a comparator (12) and a forward current correction circuit (10-1). The comparator (12) compares the forward voltage of the temperature detection diode (Dt) with a threshold voltage (VOH) and outputs a level signal corresponding to the temperature state. The forward current correction circuit (10-1) has a current mirror circuit (11a) including a PMOS transistor (11a1) and a PMOS transistor (11a2), an NMOS transistor (16), an operational amplifier (15) and a variable resistor (Rv1), and corrects the forward current (IF) of the temperature detection diode (Dt) to change the forward voltage (VF).

Description

Technical Field

[0001] The invention relates to a temperature detection device. Background Art

[0002] In recent years, the development of insulated gate bipolar transistors (IGBTs) and semiconductor modules with built-in drive circuits for driving IGBTs has been progressing. As semiconductor modules, for example, there are IPMs (Intelligent Power Modules), which are widely used in AC (Alternating Current) servos and air conditioners.

[0003] In addition, the semiconductor module has an overheat protection function for avoiding overheating and protecting the element. As the overheat protection function, there is a function of detecting overheating of the IGBT chip by monitoring the temperature with a temperature detection element mounted near the IGBT.

[0004] In addition, depending on the application of the semiconductor module, there are semiconductor modules in which the current mainly flows through the FWD (Free Wheel Diode) connected to the IGBT and the temperature of the IGBT hardly rises. In such a semiconductor module, the case temperature is detected.

[0005] Figure 4 1 is a diagram showing an example of a configuration of a conventional temperature detection circuit. The temperature detection circuit 1 includes a current source 11 , a temperature detection diode Dt, a comparator 12 , an alarm detection circuit 13 , and a threshold voltage correction circuit 14 .

[0006] Furthermore, a monitoring pad pd is connected to the temperature detection circuit 1. The monitoring pad pd is a pad for monitoring the forward voltage VF applied to the temperature detection diode Dt and / or the forward current IF flowing through the temperature detection diode Dt during the temperature detection test (not used during operation).

[0007] In the connection relationship of each circuit element, one end of the current source 11 is connected to the power supply voltage Vcc. The other end of the current source 11 is connected to the anode of the temperature detection diode Dt, the positive input terminal (+) of the comparator 12, and the monitoring pad pd. The cathode of the temperature detection diode Dt is connected to the inverting voltage terminal of the threshold voltage correction circuit 14 and the reference potential (hereinafter referred to as GND).

[0008] The negative input terminal (−) of the comparator 12 is connected to the non-inverting voltage terminal of the threshold voltage correction circuit 14 . The output terminal of the comparator 12 is connected to the input terminal of the alarm detection circuit 13 .

[0009] Here, the forward voltage VF of the temperature detection diode Dt has the characteristic of decreasing as the temperature of the housing rises. In addition, the threshold voltage correction circuit 14 outputs the threshold voltage VOH of the comparator 12 for determining whether the housing temperature is in an overheated state.

[0010] The threshold voltage correction circuit 14 sets the threshold voltage VOH to VOH < VF in a normal temperature state, for example, and sets the threshold voltage VOH to VF ≤ VOH in an overheated state. In this case, in the normal temperature state where VOH < VF, a signal of a high potential level (H level) is output from the comparator 12, and in the overheated state where VF ≤ VOH, a signal of a low potential level (L level) is output from the comparator 12.

[0011] If the alarm detection circuit 13 receives the L-level signal output from the comparator 12, it recognizes that the housing temperature has become overheated, and outputs an alarm signal, for example, for a predetermined time. It should be noted that the threshold voltage VOH generated by the threshold voltage correction circuit 14 can be corrected (adjusted), and the correction has been performed by the Zener breakdown method in the past.

[0012] On the other hand, the threshold (threshold temperature TcOH) of the housing temperature to be protected against overheating in the wafer test is calculated according to the following formula (1). The case where the housing temperature becomes equal to or higher than the threshold TcOH is the overheated state, and the case where the housing temperature is less than the threshold TcOH is the non-overheated state.

[0013] TcOH = ((VF - VOH) / VF temperature coefficient) + Ta ··· (1)

[0014] In formula (1), VF is the forward voltage (mV) of the temperature detection diode Dt at normal temperature, and VOH is the threshold voltage (mV) of the comparator 12. In addition, the VF temperature coefficient is the VF temperature change amount (mV / °C) in the range of 25°C to 125°C, and Ta is the ambient temperature (°C) of the wafer test.

[0015] As a prior art, a technique has been proposed that includes a constant voltage power supply circuit, a temperature detection diode, a constant current source, and an inverter disposed between a first voltage power supply and a second voltage power supply, and sets the gate-source voltage of the transistor constituting the inverter to the voltage across the constant current source to improve the temperature detection sensitivity (Patent Document 1).

[0016] Prior Art Documents

[0017] Patent Documents

[0018] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-312529 Summary of the Invention

[0019] Technical Problem

[0020] In the above Figure 4 In the configuration of the temperature detection circuit 1 shown, since only the threshold voltage VOH can be corrected, if the case temperature is detected due to the influence of the variation in the forward voltage VF of the temperature detection diode Dt, an error occurs.

[0021] Figure 5 Graph g1 shows the relationship between the forward voltage VF and the case temperature T (VF-T characteristics), with the vertical axis being the forward voltage VF and the horizontal axis being the case temperature T (°C).

[0022] Waveform w1 represents the representative value (Typ) of the forward voltage VF of the temperature detection diode Dt. As described above, the higher the temperature rises, the lower the forward voltage VF. On the other hand, waveforms w2 and w3 represent the deviation of the forward voltage VF. Due to the manufacturing deviation of the temperature detection diode Dt, the forward voltage VF also deviates and fluctuates up and down relative to waveform w1.

[0023] Conventionally, the case temperature that becomes overheated is detected by assuming a line (waveform w1) of a representative value of the forward voltage VF, correcting the threshold voltage VOH. However, in the case of VF-T characteristics that deviate from the representative value as in waveforms w2 and w3, case temperatures TcL and TcH are detected, respectively, and deviate from the ideal case temperature Tc after the threshold voltage VOH is set, resulting in an error in case temperature detection.

[0024] As described above, in the past, since the case temperature detection has an error, the case temperature standard is a standard that includes the error amount. Therefore, the standard width is set wide, which causes a decrease in the accuracy of temperature detection.

[0025] The present invention has been made in view of such a problem, and an object of the present invention is to provide a temperature detection device that can improve the temperature detection accuracy.

[0026] Technical Solution

[0027] In order to solve the above-mentioned problems, in one scheme, a temperature detection device is provided. The temperature detection device comprises: a temperature detection diode; a comparator, which compares the forward voltage of the temperature detection diode with a threshold voltage and outputs a level signal corresponding to the temperature state; and a forward current correction circuit, which has a current mirror circuit including a first transistor and a second transistor, a third transistor, an operational amplifier and a variable resistor, and corrects the forward current of the temperature detection diode to change the forward voltage. In addition, the first terminal of the first transistor is connected to the power supply voltage and the first terminal of the second transistor, the second terminal of the first transistor is connected to the third terminal of the first transistor, the second terminal of the second transistor and the third terminal of the third transistor, the third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode, the threshold voltage is input to the negative input terminal of the comparator, the reference voltage is input to the positive input terminal of the operational amplifier, the output terminal of the operational amplifier is connected to the second terminal of the third transistor, the negative input terminal of the operational amplifier is connected to the first terminal of the third transistor and one end of the variable resistor, and the other end of the variable resistor is connected to the cathode of the temperature detection diode and the reference potential.

[0028] In one embodiment, a temperature detection device is provided. The temperature detection device includes: a temperature detection diode; a comparator that compares the forward voltage of the temperature detection diode with a threshold voltage and outputs a level signal corresponding to the temperature state; and a forward current correction circuit that includes a current mirror circuit including a first transistor and a second transistor, a third transistor, an operational amplifier, a first resistance element, a second resistance element, and a variable resistor, and corrects the forward current of the temperature detection diode to change the forward voltage. In addition, the first terminal of the first transistor is connected to the power supply voltage and the first terminal of the second transistor, the second terminal of the first transistor is connected to the third terminal of the first transistor, the second terminal of the second transistor and the third terminal of the third transistor, the third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode, the threshold voltage is input to the negative input terminal of the comparator, the reference voltage is input to one end of the second resistance element, the other end of the second resistance element is connected to one end of the variable resistor and the positive input terminal of the operational amplifier, the other end of the variable resistor is connected to the reference potential, the output terminal of the operational amplifier is connected to the second terminal of the third transistor, the negative input terminal of the operational amplifier is connected to the first terminal of the third transistor and one end of the first resistance element, and the other end of the first resistance element is connected to the cathode of the temperature detection diode and the reference potential.

[0029] In one embodiment, a temperature detection device is provided. The temperature detection device includes: a temperature detection element; a comparator that compares the forward voltage of a temperature detection diode with a threshold voltage and outputs a level signal corresponding to a temperature state; and a forward current correction circuit that corrects the forward current of the temperature detection element to change the forward voltage.

[0030] Effects of the Invention

[0031] The temperature detection accuracy can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a diagram showing an example of the configuration of a temperature detection device (first embodiment).

[0033] Figure 2 It is a diagram for explaining the calibration operation of the temperature detection device.

[0034] Figure 3 It is a diagram showing an example of the configuration of a temperature detection device (second embodiment).

[0035] Figure 4 This is a diagram showing an example of the configuration of a conventional temperature detection circuit.

[0036] Figure 5 This is a diagram for explaining a state in which an error occurs in case temperature detection.

[0037] Explanation of symbols

[0038] 1-1 Temperature detection device

[0039] 10-1 Forward Current Correction Circuit

[0040] 11a Current mirror circuit

[0041] 11a1 first transistor (PMOS transistor), 11a2 second transistor (PMOS transistor)

[0042] 12 Comparator

[0043] 13 Alarm detection circuit

[0044] 14 Threshold voltage correction circuit

[0045] 15 Operational Amplifier

[0046] 16 The third transistor (NMOS transistor)

[0047] Dt Temperature detection diode

[0048] PD monitoring pad

[0049] Rv1 variable resistor

[0050] VREF reference voltage

[0051] IF forward current

[0052] VF forward voltage

[0053] VOH Threshold Voltage

[0054] Vout Output voltage

[0055] Vcc supply voltage

[0056] V1 Voltage

[0057] I1 Current DETAILED DESCRIPTION

[0058] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that in this specification and the drawings, elements having substantially the same function are denoted by the same reference numerals to omit repeated descriptions.

[0059] [First embodiment]

[0060] Figure 1 1 is a diagram showing an example of the configuration of a temperature detection device. The temperature detection device 1-1 of the first embodiment includes a temperature detection diode Dt as a temperature detection element, a comparator 12, an alarm detection circuit 13, a threshold voltage correction circuit 14, and a forward current correction circuit 10-1. In addition, the forward current correction circuit 10-1 includes a current mirror circuit 11a, an operational amplifier 15, a transistor 16, and a variable resistor Rv1.

[0061] The current mirror circuit 11a includes transistors 11a1 and 11a2 (a first transistor and a second transistor). Figure 1 In the example of FIG. 1 , P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistors (hereinafter referred to as PMOS transistors 11 a 1 and 11 a 2 ) are used.

[0062] In addition, Figure 1 In the example, transistor 16 (third transistor) uses an N-channel MOSFET (hereinafter referred to as NMOS transistor 16). It should be noted that for PMOS transistors 11a1, 11a2 and NMOS transistor 16, the first terminal corresponds to the source, the second terminal corresponds to the gate, and the third terminal corresponds to the drain.

[0063] In the connection relationship of each circuit element, the source of the PMOS transistor 11a1 is connected to the power supply voltage Vcc and the source of the PMOS transistor 11a2. The gate of the PMOS transistor 11a1 is connected to the drain of the PMOS transistor 11a1, the gate of the PMOS transistor 11a2 and the drain of the NMOS transistor 16.

[0064] The drain of the PMOS transistor 11 a 2 is connected to the monitoring pad pd, the positive input terminal (+) of the comparator 12 , and the anode of the temperature detection diode Dt.

[0065] The reference voltage VREF is input to the positive input terminal (+) of the operational amplifier 15, and the output terminal of the operational amplifier 15 is connected to the gate of the NMOS transistor 16. The negative input terminal (-) of the operational amplifier 15 is connected to the source of the NMOS transistor 16 and one end of the variable resistor Rv1.

[0066] The other end of the variable resistor Rv1 is connected to the cathode of the temperature detection diode Dt, the inverting voltage terminal of the threshold voltage correction circuit 14, and GND. The positive input terminal of the threshold voltage correction circuit 14 is connected to the negative input terminal (-) of the comparator 12. The output terminal of the comparator 12 is connected to the input terminal of the alarm detection circuit 13.

[0067] Here, the forward current correction circuit 10-1 can correct the forward current IF of the temperature detection diode Dt. In this case, according to the function of the operational amplifier 15, the current I1 flowing in the drain of the NMOS transistor 16 changes in such a way that the potential on the source side of the NMOS transistor 16, that is, the voltage V1, becomes equal to the reference voltage VREF (V1=VREF). Thus, the forward current IF is corrected. In addition, the reference voltage VREF is generated by using MOS (regulator, etc.) in the main chip in the package in which the temperature detection device 1-1 is installed.

[0068] The flow of the correction operation of the forward current IF is described. First, when the resistance value of the variable resistor Rv1 is changed in a decreasing direction, the voltage V1 decreases. If the voltage V1 decreases, the potential difference between the voltage V1 and the reference voltage VREF increases, so the output voltage Vout of the operational amplifier 15 increases to increase the voltage V1.

[0069] If the output voltage Vout of the operational amplifier 15 increases, the current I1 flowing through the NMOS transistor 16 increases. If the current I1 increases, the forward current IF that increases according to the mirror ratio of the current mirror circuit 11a flows through the temperature detection diode Dt. In this way, if the resistance value of the variable resistor Rv1 is reduced, the forward current IF is corrected in the direction of increase.

[0070] On the other hand, when the resistance value of the variable resistor Rv1 increases, the voltage V1 increases. If the voltage V1 increases, the potential difference between the voltage V1 and the reference voltage VREF decreases, so the output voltage Vout of the operational amplifier 15 decreases to reduce the voltage V1.

[0071] If the output voltage Vout of the operational amplifier 15 decreases, the current I1 flowing through the NMOS transistor 16 decreases. If the current I1 decreases, the forward current IF that decreases according to the mirror ratio of the current mirror circuit 11a flows through the temperature detection diode Dt. In this way, if the resistance value of the variable resistor Rv1 is increased, the forward current IF is corrected in the direction of decrease.

[0072] It should be noted that the detection of the forward voltage VF and the correction of the threshold voltage VOH and / or the variable control of the resistance value of the variable resistor Rv1 can be implemented by a higher-level processor (not shown). In this case, a plurality of set values ​​for the threshold voltage VOH and / or the resistance value of the variable resistor Rv1 are stored in a memory (e.g., EPROM (Erasable Programmable Read Only Memory)). After detecting the forward voltage VF, the higher-level processor sets the desired value stored in the memory to the threshold voltage correction circuit 14 and / or the variable resistor Rv1.

[0073] Figure 2 Graph g2 is a diagram for explaining the correction operation performed by the temperature detection device. Graph g2 shows the relationship between the forward current IF and the forward voltage VF, with the vertical axis being the forward current IF and the horizontal axis being the forward voltage VF.

[0074] The waveform w11 represents the forward current IF when the forward voltage VF of the temperature detection diode Dt is a representative value (Typ). Since the forward voltage VF varies as described above, the forward current IF varies with respect to the waveform w11 in accordance with the variation of the forward voltage VF.

[0075] The waveform w12 represents the forward current IF when the forward voltage VF deviates from the representative value in the decreasing direction. The waveform w13 represents the forward current IF when the forward voltage VF deviates from the representative value in the increasing direction.

[0076] On the other hand, the threshold voltage VOH is set by the above-mentioned threshold voltage correction. The threshold voltage VOH is set to an ideal forward voltage VF (hereinafter referred to as an ideal VF value) which is a reference for determining whether or not the overheat state is present.

[0077] It should be noted that although the ideal VF value = threshold voltage VOH, this is the VF value at high temperature when the shell temperature is detected. In addition, since the wafer test is carried out at room temperature, Figure 4 The VF-T characteristics as described above are obtained, and the VF value at high temperature is estimated at room temperature.

[0078] In the graph g2, with respect to the waveform w12, the forward voltage VF becomes a VF value (forward voltage VF1) lower than the ideal VF value. Therefore, the forward current IF is corrected to change the forward voltage VF. That is, the forward current IF is corrected in the direction of increase (arrow a1) so that the forward voltage VF1 becomes the ideal VF value.

[0079] In this case, the resistance value of the variable resistor Rv1 is controlled to decrease. By such control, the case temperature TcL at the forward voltage VF1 approaches the ideal case temperature Tc at the threshold voltage VOH.

[0080] In addition, with respect to waveform w13, the forward voltage VF becomes a VF value (forward voltage VF2) larger than the ideal VF value. Therefore, the forward current IF is corrected to change the forward voltage VF. That is, the forward current IF is corrected in the direction of decrease (arrow a2) so that the forward voltage VF2 becomes the ideal VF value.

[0081] In this case, the resistance value of the variable resistor Rv1 is controlled to increase. By such control, the case temperature TcH at the forward voltage VF2 approaches the ideal case temperature Tc at the threshold voltage VOH.

[0082] As described above, when only the threshold voltage VOH is corrected, the case temperature detection generates an error due to the influence of the forward voltage VF variation. In order to eliminate this error, the present invention is configured to variably control the forward current IF.

[0083] That is, in the present invention, in addition to correcting the threshold voltage VOH, the forward current IF is also corrected. In the correction of the forward current IF, based on the detected forward voltage VF, the forward current IF is increased to increase the forward voltage VF, or the forward current IF is reduced to reduce the forward voltage VF. Thus, the error of the shell temperature detection can be reduced, and the temperature detection accuracy can be improved.

[0084] It should be noted that in the conventional configuration, the threshold voltage VOH is corrected by Zener breakdown, so one pad is required for one-bit correction, whereas in the correction of the present invention, correction is performed using a set value pre-stored in an EPROM.

[0085] Therefore, even if the number of bits is increased, the number of pads does not change, and since the device mounting area of ​​EPROM is smaller than the mounting area of ​​Zener breakdown, there is also an effect of reducing the increase in mounting area.

[0086] [Second embodiment]

[0087] Figure 3 The temperature detection device 1-2 of the second embodiment includes a temperature detection diode Dt, a comparator 12, an alarm detection circuit 13, a threshold voltage correction circuit 14, and a forward current correction circuit 10-2.

[0088] The forward current correction circuit 10 - 2 includes a current mirror circuit 11 a , an operational amplifier 15 , a transistor 16 , a resistor R1 (a first resistor element), a resistor R2 (a second resistor element), and a variable resistor Rv2 .

[0089] In the connection relationship of each circuit element, the source of the PMOS transistor 11a1 is connected to the power supply voltage Vcc and the source of the PMOS transistor 11a2. The gate of the PMOS transistor 11a1 is connected to the drain of the PMOS transistor 11a1, the gate of the PMOS transistor 11a2 and the drain of the NMOS transistor 16.

[0090] The drain of the PMOS transistor 11 a 2 is connected to the monitoring pad pd, the positive input terminal (+) of the comparator 12 , and the anode of the temperature detection diode Dt.

[0091] The reference voltage VREF is input to one end of the resistor R2, and the other end of the resistor R2 is connected to one end of the variable resistor Rv2 and the positive input terminal (+) of the operational amplifier 15. The other end of the variable resistor Rv2 is connected to GND.

[0092] The output terminal of the operational amplifier 15 is connected to the gate of the NMOS transistor 16. The negative input terminal (-) of the operational amplifier 15 is connected to the source of the NMOS transistor 16 and one end of the resistor R1.

[0093] The other end of the resistor R1 is connected to the cathode of the temperature detection diode Dt, the inverting voltage terminal of the threshold voltage correction circuit 14, and GND. The positive input terminal of the threshold voltage correction circuit 14 is connected to the negative input terminal (-) of the comparator 12. The output terminal of the comparator 12 is connected to the input terminal of the alarm detection circuit 13.

[0094] Here, the forward current correction circuit 10-2 can correct the forward current IF of the temperature detection diode Dt. In this case, the current I1 flowing in the drain of the NMOS transistor 16 changes based on the voltage Vin obtained by dividing the reference voltage VREF by the resistor R2 and the variable resistor Rv2. Thus, the forward current IF is corrected.

[0095] The flow of the correction operation of the forward current IF is described. The input voltage Vin of the operational amplifier 15 is Vin=VREF×(Rv2 / (R2+Rv2)). First, when the resistance value of the variable resistor Rv2 is changed in an increasing direction, the input voltage Vin of the operational amplifier 15 increases.

[0096] If the input voltage Vin of the operational amplifier 15 increases, the output voltage Vout of the operational amplifier 15 increases, and the current I1 flowing through the NMOS transistor 16 increases. If the current I1 increases, the forward current IF that increases according to the mirror ratio of the current mirror circuit 11a flows through the temperature detection diode Dt. In this way, if the resistance value of the variable resistor Rv2 is increased, the forward current IF is corrected in the direction of increase.

[0097] On the other hand, when the resistance value of the variable resistor Rv2 is changed in a decreasing direction, the input voltage Vin of the operational amplifier 15 decreases. When the input voltage Vin of the operational amplifier 15 decreases, the output voltage Vout of the operational amplifier 15 decreases, and the current I1 flowing through the NMOS transistor 16 decreases.

[0098] When the current I1 decreases, the forward current IF that decreases according to the mirror ratio of the current mirror circuit 11a flows through the temperature detection diode Dt. In this way, when the resistance value of the variable resistor Rv2 is reduced, the forward current IF is corrected in the direction of decrease.

[0099] It should be noted that the detection of the forward voltage VF and the correction of the threshold voltage VOH and / or the variable control of the resistance value of the variable resistor Rv2 can be implemented by the host processor in the same manner as in the first embodiment. In addition, after detecting the forward voltage VF, the host processor sets the desired value stored in the memory to the threshold voltage correction circuit 14 and / or the variable resistor Rv2.

[0100] Thus, in the second embodiment, in addition to the correction of the threshold voltage VOH, the forward current IF is also corrected as in the first embodiment. In the correction of the forward current IF, the forward current IF is increased to increase the forward voltage VF, or the forward current IF is decreased to decrease the forward voltage VF based on the detected forward voltage VF. Thus, the error of the housing temperature detection can be reduced, and the temperature detection accuracy can be improved.

[0101] Although the embodiments are described above, the configurations of the various parts described in the embodiments can be replaced with other configurations having the same functions. In addition, other arbitrary configurations and / or processes can also be added.

Claims

1. A temperature detection device, characterized in that: have: Diode for temperature detection; a comparator that compares the forward voltage of the temperature detection diode with a threshold voltage and outputs a level signal corresponding to the temperature state; as well as A forward current correction circuit includes a current mirror circuit including a first transistor and a second transistor, a third transistor, an operational amplifier, and a variable resistor, and corrects the forward current of the temperature detection diode to change the forward voltage. A first terminal of the first transistor is connected to a power supply voltage and a first terminal of the second transistor, and a second terminal of the first transistor is connected to a third terminal of the first transistor, a second terminal of the second transistor, and a third terminal of the third transistor. The third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode, and the threshold voltage is input to the negative input terminal of the comparator. A reference voltage is input to a positive input terminal of the operational amplifier, an output terminal of the operational amplifier is connected to the second terminal of the third transistor, and a negative input terminal of the operational amplifier is connected to a first terminal of the third transistor and one end of the variable resistor. The other end of the variable resistor is connected to the cathode of the temperature detection diode and a reference potential, and the resistance value of the variable resistor is set by a host processor.

2. The temperature detection device according to claim 1, characterized in that: By reducing the resistance value of the variable resistor, the forward current is increased to increase the forward voltage, and by increasing the resistance value of the variable resistor, the forward current is reduced to reduce the forward voltage.

3. A temperature detection device, characterized in that: have: Diode for temperature detection; a comparator that compares the forward voltage of the temperature detection diode with a threshold voltage and outputs a level signal corresponding to the temperature state; and a forward current correction circuit, comprising a current mirror circuit including a first transistor and a second transistor, a third transistor, an operational amplifier, a first resistance element, a second resistance element, and a variable resistor, and correcting the forward current of the temperature detection diode to change the forward voltage; A first terminal of the first transistor is connected to a power supply voltage and a first terminal of the second transistor, and a second terminal of the first transistor is connected to a third terminal of the first transistor, a second terminal of the second transistor, and a third terminal of the third transistor. The third terminal of the second transistor is connected to the positive input terminal of the comparator and the anode of the temperature detection diode, and the threshold voltage is input to the negative input terminal of the comparator. A reference voltage is input to one end of the second resistance element, the other end of the second resistance element is connected to one end of the variable resistor and the positive input terminal of the operational amplifier, and the other end of the variable resistor is connected to a reference potential. The output terminal of the operational amplifier is connected to the second terminal of the third transistor, and the negative input terminal of the operational amplifier is connected to the first terminal of the third transistor and one end of the first resistor. The other end of the first resistor element is connected to the cathode of the temperature detection diode and the reference potential.

4. The temperature detection device according to claim 3, characterized in that: By reducing the resistance value of the variable resistor, the forward current is reduced and the forward voltage is lowered, and by increasing the resistance value of the variable resistor, the forward current is increased and the forward voltage is increased.

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