JPH07134070A - Abnormality notifying circuit and temperature detecting circuit - Google Patents

Abstract

PURPOSE:To obtain a temperature detecting circuit which can accurately detect the internal overheating state of a semiconductor element and, at the same time, can detect the fault of a temperature detecting section and output the abnormality. CONSTITUTION:A temperature detecting circuit detects the internal temperature of a semiconductor element by utilizing the negative temperature characteristic of a diode 11 and, when the temperature exceeds a certain value and the potential (V7) at a point 7 becomes higher than the potential (V9) at another point 9, the output voltage of an output terminal 13 is changed from an 'L' level to an 'H' level by turning on a transistor 10 and turning off another transistor 17 by using the differential output of a comparator composed of a first transistor 21 and second transistor 18. In case the potential V9 becomes abnormally high due to the opening state between both terminals of the diode 11 and exceeds a certain level V2 (the sum of the forward voltage VF (D19) of a diode 19 and the VBE (Tr20) of an output driving transistor 20), the transistor 20 wired-OR connected with the differential output transistor 10 is turned on and the output terminal 13 becomes an 'H' level. Therefore, the fault (open) of the temperature detecting circuit can be displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an abnormality notification circuit,
For example, the present invention relates to a temperature detection circuit using the temperature characteristic of a diode.

[0002]

2. Description of the Related Art Generally, semiconductor integrated circuits (hereinafter referred to as ICs) used in various electronic devices including computers.
Have problems such as malfunction and destruction due to heat, and preventing them is an important issue. Especially in recent years, since the power consumption per IC chip has increased with the increase in speed and integration, abnormal temperature rise of the IC chip is detected early and an alarm is issued or the power is cut off.
The need to deal with heat is increasing.

From such a point of view, a temperature detecting circuit incorporated in an IC chip for detecting an overheated state has been proposed or implemented, one example of which is disclosed in Japanese Patent Laid-Open No. 60-47934. Have been described. In this circuit, when the temperature reaches a predetermined value, the level of the output voltage can be inverted to detect an abnormal temperature rise.

Another circuit configuration is shown in FIG. 7, for example. Hereinafter, the configuration and operation of this circuit will be described in detail.

In this circuit, each emitter is connected to the power supply line 1
A current mirror circuit is formed by PNP type transistors 81, 82, 83, 84 and 85 which are connected to 2 and whose bases are commonly connected. The collector of the transistor 81 is connected to the base and also to the constant current source 5, whereby the transistors 82 to 85 are respectively
It works as a constant current source for the following circuit elements.

The collector of the transistor 82 is commonly connected to the emitters of a PNP type first transistor 21 and a second transistor 18 which form a base input comparator. The collectors of these transistors are
Each of them is connected to the collectors of NPN transistors 23 and 16 forming a current mirror circuit. The emitters of the transistors 23 and 16 are both connected to the ground line 14.

The base of the first transistor 21 is connected to the constant current source 15 via the resistor 1 and to the ground line 14 via the resistor 2, and is determined by the voltage division ratio of the resistor 1 and the resistor 2. A constant reference voltage (independent of temperature) is applied to the base of the first transistor 21.

The base of the second transistor 18 is connected to the collector of the transistor 83 and has a negative temperature characteristic (a characteristic in which the internal resistance decreases as the temperature rises).
Connected to the anode of the diode 11 having
The cathode of the diode 11 is connected to the ground line 14. As a result, the anode terminal voltage of the diode 11 is applied to the base of the second transistor 18.

The collector of the second transistor 18 is connected to the collector of the transistor 16 as described above, and is also connected to the base of the NPN type differential output transistor 10 whose emitter is connected to the ground line 14. The collector of the differential output transistor 10 is connected to the collector of the transistor 84 and the base of an NPN type output transistor 17 whose emitter is connected to the ground line 14. The collector of the output transistor 17 is connected to the collector of the transistor 85 and the output terminal 13.
The output terminal 13 outputs a level voltage indicating whether the detected temperature is normal or abnormal, corresponding to the on / off operation of the output transistor 17.

The operation of the conventional temperature detecting circuit having the above configuration will be described. The potential (reference voltage) of the base terminal 7 of the first transistor 21 is V7, and the potential of the base terminal 9 of the second transistor 18 is V9. This circuit
The temperature is detected by using the negative temperature characteristic of the diode 11, and when the temperature exceeds a certain temperature and V7> V9, the first
That turns on the transistor 10 and turns off the transistor 17 by the differential output of the comparator composed of the transistor 21 and the second transistor 18, and changes the output voltage of the output terminal 13 from the “L” level to the “H” level. Is.

The temperature characteristic of the diode 11 is about -2 mV /
° C, ie diode 1 for every 1 degree increase in temperature
It is assumed that the forward voltage of 1 decreases by about 2 mV, and the forward voltage V of the diode 11 at room temperature (25 ° C.)
If the current value of the constant current source 5 is set so that F (D11) is 700 mv, V9 is 700 m at room temperature.
It becomes V. Assuming that it is detected that the temperature has reached 150 ° C, V7 is 450m from the following equation (1).
The values of the resistors 1 and 2 may be set so as to be V.

V7 = 700 [mV]-(150-25) [° C] × 2 [mV / ° C] (1) First, considering the case where the temperature is lower than the detected temperature 150 ° C, the second The base voltage V9 of the transistor 18, that is, the anode terminal voltage of the diode 11 is higher than the base voltage V7 (= 450 mV) of the first transistor 21. Therefore, the first transistor 21
Is almost on, and the second transistor 18 is almost off. Therefore, the differential output transistor 10 is turned off and the output transistor 17 is turned on, so that an “L” level voltage is output from the output terminal 13.

On the other hand, the base voltage V9 of the second transistor 18, that is, the anode terminal voltage of the diode 11 decreases as the temperature rises, and the temperature is detected at 150 ° C.
When it exceeds C, V9 becomes smaller than V7 (= 450mV). Therefore, the first transistor 21 is almost off and the second transistor 18 is almost on.
Therefore, the differential output transistor 10 is turned on and the output transistor 17 is turned off, so that an “H” level voltage is output from the output terminal 13.

In this way, by detecting the temperature by utilizing the negative temperature characteristic of the diode 11, a voltage of "H" level is output from the output terminal 13 in a state where V7> V9 is exceeded beyond a certain temperature. The abnormal temperature can be detected.

[0015]

In the conventional temperature detecting circuit (FIG. 7), the abnormal temperature is detected as described above, but it is not possible to cope with the failure of the temperature detecting circuit itself. That is, for example, when a short circuit or an open state occurs between both terminals due to a failure of the temperature detecting diode 11 itself or a disconnection of wiring, it is possible to detect not only the failure but also a temperature abnormality. There wasn't.

That is, in FIG. 7, the diode 11
Assuming that an open state is established between the two terminals, a voltage V9 of V7 or higher is applied to the base of the second transistor 18. Since the above circuit configuration can detect the temperature abnormality only when V9 becomes smaller than V7, in the above case (both the terminals of the diode 11 are open), the temperature is 150 ° C or more. Even if it becomes, it will not be detected. Of course, the failure of the temperature detection circuit itself (open state between both terminals of the diode 11) is not detected. In order to detect the abnormality of the temperature detection circuit itself, it is necessary to separately provide a circuit having the same configuration as the above circuit, so that the number of elements increases and the IC
Area efficiency in the chip becomes poor. This problem also applies to the circuit described in the above-mentioned publication (JP-A-60-47934).

Further, in FIG. 7, if both terminals of the diode 11 are short-circuited, the base voltage V9 of the second transistor 18 becomes the ground level, and in this case also, accurate temperature detection cannot be performed and the short-circuit occurs. It does not detect what you have done.

Further, there are the following problems. That is, in the base input comparator using the PNP transistor as shown in FIG. 7, the lower limit value V1 of the comparable range on the ground level side is normally given by the following equation (2).

V1 = VBE (Tr10) + VCE (Tr18) -VBE (Tr18) (2) That is, in the comparator having the above configuration, when the potential of V9 drops to V1 or less, the differential output transistor 10
Can no longer be turned on, and the differential output transistor 10 is turned off regardless of the value of V9. Usually, VBE (Tr10) ≧ VBE (Tr18) and V at high temperature
Since CE (Tr18) is 300 to 400 mV, it means that the operation up to about 300 to 400 mV is the limit at high temperature. Therefore, the forward voltage VF of the diode 11 is
(D11), that is, when the anode terminal voltage of the diode 11 becomes V1 or less, the differential output transistor 10 is turned off, and even if it is actually overheated (for example, the terminal voltage of the diode 11 is 400 mV). Then, this corresponds to 175 ° C.), and the “L” level is output to the output terminal 13, and it is erroneously detected as normal despite the abnormal temperature.

The present invention has been made to solve the above problems, and can accurately detect an overheated state inside a semiconductor element, and can also detect a failure in a temperature detection section and output an abnormal output. The purpose is to obtain a temperature detection circuit.

[0021]

According to a first aspect of the present invention, there is provided an abnormality notification circuit which compares a voltage source whose output voltage changes with an output voltage of the voltage source with a predetermined reference voltage, and outputs the reference voltage. Means for outputting an abnormality notification signal when the voltage is lower than the voltage, and means for outputting an abnormality notification signal when the output voltage is higher than a second reference voltage higher than the reference voltage,
It is characterized by including.

According to a second aspect of the present invention, there is provided the abnormality notification circuit according to the first aspect, wherein the voltage source is a diode whose forward voltage changes with temperature.

According to a third aspect of the present invention, there is provided a temperature detection circuit in which a first transistor to which a predetermined reference voltage is applied is applied to the base and a terminal voltage of a diode which changes according to temperature is applied to the base. In a temperature detection circuit having a base input comparator including
A differential output transistor that is turned on and off according to a difference between a reference voltage applied to the base of the first transistor and a terminal voltage of the diode applied to the base of the second transistor; On the other hand, an output driving transistor, which is wired-OR connected with a collector and an emitter in common and driven by a diode terminal voltage applied to the base of the second transistor, and an ON / OFF operation of the differential output transistor or the output driving transistor. Accordingly, an output terminal for outputting a signal voltage indicating normality / abnormality of the terminal voltage of the diode is provided.

According to a fourth aspect of the present invention, in the temperature detecting circuit according to the third aspect, one or a plurality of other diodes are connected between the base of the output drive transistor and the base of the second transistor. It is characterized by that.

[0025]

In the abnormality notification circuit according to the invention described in claim 1,
As a result of the comparison between the output voltage and the reference voltage, the abnormality notification signal is output when the output voltage is lower than the reference voltage, and the abnormality notification signal is output when the output voltage is higher than the second reference voltage.

In the temperature detecting circuit according to the second aspect of the present invention, the terminal voltage of the diode is used as the output voltage to detect the abnormal state of the temperature. However, the output voltage is not only detected when the abnormal temperature is detected. The abnormality notification signal is output even when the voltage is smaller (or larger) than the second reference voltage.

In the temperature detecting circuit according to the third aspect of the present invention, the abnormal temperature is detected by comparing the terminal voltage of the diode with the reference voltage, and, for example, the two terminals of the diode are disconnected to be in an open state. In case of abnormal fluctuation of the base input of the second transistor,
This is detected and an abnormality notification signal is output.

In the temperature detecting circuit according to the fourth aspect of the present invention, another diode is connected between the base of the output driving transistor and the base of the second transistor to drive the output driving transistor. The required terminal voltage of the diode can be set arbitrarily.

[0029]

The present invention will be described in detail below with reference to the drawings.

First Embodiment FIG. 1 shows a temperature detecting circuit according to a first embodiment of the present invention. In this figure, the same parts as those in the conventional example (FIG. 7) are designated by the same reference numerals.

In this circuit, each emitter is connected to the power supply line 1
A current mirror circuit is formed by PNP-type transistors 81, 82, 83, 84, 85 and 86 which are connected to 2 and whose bases are commonly connected. The collector of the transistor 81 is connected to the base and is also connected to the constant current source 5, so that the transistors 82 to 86 respectively act as constant current sources for the following circuit elements.

The collector of the transistor 82 is commonly connected to the emitters of the PNP type first transistor 21 and the second transistor 18 which form a base input comparator. Of these, the collector of the first transistor is connected to the collector of an NPN transistor 23 having a base-collector connection. This transistor 23 forms a current mirror circuit together with an NPN type transistor 24 having a base-emitter junction area twice as large as that of the transistor 23. The emitters of the transistors 23 and 24 are both connected to the ground line 14.

The base of the first transistor 21 is connected to the constant current source 15 via the resistor 1 and the ground line 14 via the resistor 2, and is determined by the voltage division ratio of the resistor 1 and the resistor 2. A constant reference voltage (independent of temperature) is applied to the base of the first transistor 21.

The base of the second transistor 18 is connected to the collector of the transistor 83 and the anode of the diode 11 having a negative temperature characteristic, and the cathode of the diode 11 is connected to the ground line 14. . As a result, the anode terminal voltage of the diode 11 is applied to the base of the second transistor 18.

The collector of the transistor 24 is connected to the collector of the transistor 86 and also to the base of the NPN type differential output transistor 10 whose emitter is connected to the ground line 14. The collector of the differential output transistor 10 is connected to the collector of the transistor 84 and the base of an NPN type output transistor 17 whose emitter is connected to the ground line 14. The collector of the output transistor 17 is connected to the collector of the transistor 85, and
It is connected to the output terminal 13. From this output terminal 13, in response to the on / off operation of the output transistor 17,
The level voltage that indicates whether the detected temperature is normal or abnormal is output.

Further, this circuit is provided with an NPN type output drive transistor 20 which is wired-OR connected to the differential output transistor 10 with a collector and an emitter in common, and its base has a second anode having an anode. Is connected to the cathode of a second diode 19 connected to the base of the transistor 18. The output drive transistor 20 is directly driven by the anode terminal voltage of the diode 11 and indirectly by the cathode terminal voltage of the second diode 19. The level voltage indicating normality / abnormality of the temperature detection circuit is output from the output terminal 13 by the on / off operation of the output drive transistor 20. That is, in the present circuit, not only the overheated state of the circuit can be detected, but also when a failure such as an open due to a disconnection of the diode 11 itself or the wiring thereof occurs, it is possible to detect this and notify the abnormality. This point has the first feature.

Also, in this embodiment, unlike the conventional example (FIG. 7), the differential output is generated by the second transistor 18 as described above.
However, since it is taken from the collector of the first transistor 21, even if a short circuit occurs in the diode 11 itself or the wiring thereof and the anode terminal voltage of the diode 11 becomes the ground level, this is detected and the abnormality is notified. It becomes possible to do. This point has a second feature.

The operation of the conventional temperature detecting circuit having the above configuration will be described. The basic operation of this circuit, that is, the operation of detecting the overheated state when there is no failure in the circuit is almost the same as in the case of the conventional example (FIG. 7).
The temperature is detected by using the negative temperature characteristic of the first transistor 21 and the second transistor 18 under the condition that the potential at the point 7 (V7)> the potential at the point 9 (V9) exceeds a certain temperature. By turning on the transistor 10 and turning off the transistor 17 by the differential output of the comparator, the output voltage of the output terminal 13 is changed from the “L” level to the “H” level.

Specifically, as in the case of FIG. 7, the temperature characteristic of the diode 11 (= about -2 mV / ° C), the value of V7 (= 450 mV) and the value of V9 at room temperature (= 700).
mV) is set, first, the temperature is the detected temperature 15
When it is lower than 0 ° C., V9 is higher than the base voltage V7 (= 450 mV) of the first transistor 21. Therefore, the first transistor 21 is almost on, the second transistor 18 is almost off, and the transistors 23 and 24 are on, so that the differential output transistor 10 is off and the output transistor 1
7 is turned on. Therefore, the voltage of "L" level is output from the output terminal 13, and it is displayed that the temperature is lower than the detected temperature.

Further, V9 decreases as the temperature rises, and when the temperature exceeds the detection temperature of 150 ° C, V9 becomes V7 (= 4
50 mV). Therefore, the second transistor 18 is turned on, the first transistor 21 is turned off, and the transistors 23 and 24 are also turned off. Therefore, the differential output transistor 10 is turned on and the output transistor 17 is turned on. Therefore, the “H” level voltage is output from the output terminal 13.

In this manner, by detecting the temperature by utilizing the negative temperature characteristic of the diode 11, the voltage of "H" level is output from the output terminal 13 in the state where V7> V9 is exceeded beyond a certain temperature. The abnormal temperature can be detected.

On the other hand, in the present circuit, the differential output transistor 10 can be kept on even if, for example, both terminals of the diode 11 are short-circuited and V9 becomes the ground level. Therefore, also in this case, the "H" level voltage indicating the abnormality is output from the output terminal 13. That is, as shown in FIG. 2, the output terminal 13 becomes "H" level in the entire range of the level V7 or lower (of course, V1 or lower), and the diode 11 or its wiring is broken (short-circuited) or overheated. Is displayed. This is the action corresponding to the above-mentioned second characteristic point.

Further, in this circuit, V9 increases and the forward voltage VF (D19) of the diode 19 and the base-emitter voltage VBE (Tr20) of the output drive transistor 20 (VF).
When (D19) + VBE (Tr20) = V2) is exceeded, the differential output transistor 10 and the output drive transistor 20 wired-OR connected are turned on. Therefore, even if the diode 11 or the wiring thereof is opened between both terminals of the diode 11 and V9 rises abnormally and exceeds a certain level V2, as shown in FIG. It becomes the “H” level, and it can be displayed that the diode 11 or the wiring thereof is open (open) or overheated. This is the action corresponding to the above-mentioned first characteristic point.

As described above, the present circuit complements the drawbacks of the conventional circuit in the above two points.

As shown in FIG. 2, the output voltage of the output terminal 13 can be inverted within the range of V2 or more with respect to the value of V9, but the value of V2 is determined by connecting the diodes 19 in a plurality of stages. Can be set arbitrarily.

In the present embodiment, the temperature detection circuit using the temperature characteristic of the diode 11 has been described as an example, but by adopting a configuration in which another voltage is input instead of the diode 11, the temperature detection circuit other than the temperature detection circuit is used. It is also possible to configure a comparator used in the application.

Second Embodiment FIG. 3 shows a temperature detecting circuit according to a second embodiment of the present invention. This circuit includes a first transistor 21
The base potential V7 of (1) is provided with hysteresis so as to prevent chattering of the output level with respect to a slight temperature change. In order to realize this, in this circuit, N is connected between the resistor 2 and the ground line 14 via the resistor 4.
Connect PN type transistor 6 (collector to resistor 4,
The emitter is connected to the ground line 14), the resistor 3 is connected in parallel with these, and the base of the transistor 6 is connected to the collector of the differential output transistor 10.
Other configurations are the same as those in FIG.

The operation of the temperature detection circuit having the above configuration will be described.

Now, the temperature is the detected temperature (for example, 150 °).
C) or less and the differential output transistor 10 is off, the transistor 6 is turned on, so that the potential V of the point 7 is V.
7 becomes a potential V7L determined by the voltage division ratio of the value of the resistor 1 and the combined resistance value of the resistors 2, 3 and 4. On the other hand, the temperature exceeds the detection temperature (for example, 150 ° C) and the differential output transistor 1
When 0 is on, the transistor 6 is off,
The potential V7 at the point 7 becomes a potential V7H (<V7L) determined by the voltage division ratio between the value of the resistor 1 and the combined resistance value of the resistors 2, 3 and 4.

Therefore, as shown in FIG. 4A, the potential V7 at the point 7 changes to V7H or V7L in accordance with the change in V9, and the output voltage of the output terminal 13 as shown in FIG. 4B. Will change with hysteresis. Therefore, it is possible to prevent chattering of the output level due to a slight temperature change.

Third Embodiment FIG. 5 shows a temperature detecting circuit according to a third embodiment of the present invention. In the first and second embodiments, the temperature detecting diode 11 is arranged on the same IC chip. However, in the present embodiment, since the open and short of the diode 11 can be detected, the diode 11 can be replaced by another one. It is arranged in the IC chip to detect the temperature of the IC chip.

That is, as shown in FIG. 5, the diode 11 is arranged on an IC chip 26 to be monitored for temperature, which is separate from the IC chip 25 on which the temperature detection circuit is mounted, and wirings 27 and 28 such as bonding wires are used. And diode 1
The anode of No. 1 is connected to the point 9 of the temperature detection circuit from the external terminal 30 via the external terminal 29, and the diode 1
The cathode of No. 1 is connected to the point 7 of the temperature detection circuit from the external terminal 32 through the external terminal 31. Other configurations are the same as those in FIG.

According to this structure, for example, when the IC chip 26 has a power output section serving as a main heat source, the external IC chip 25 monitors the power output section, and the output result of the output terminal 13 is compared with the power output section. The power output can be prevented by connecting to the heating control system of the output. Further, even if the wire 27 or 28 is broken or short-circuited, it can be detected as an abnormality. Therefore, it is possible to reliably avoid troubles such as abnormal heat generation in a state where overheat cannot be detected due to a failure of the temperature detection circuit itself. it can.

Fourth Embodiment FIG. 6 shows a temperature detecting circuit according to a fourth embodiment of the present invention. In this circuit, an NPN type first transistor 51 and a second transistor 48 are used instead of the PNP type first transistor 21 and the second transistor 18 in FIG. 1 to form a base input comparator. A reference voltage from the constant current source 45 is applied to the base of the first transistor 51, and the second transistor 4
The cathode of the diode 11 is connected to the base of 8.
Reference numerals 61 to 63 are constant current sources, and terminals 65 and 66 are a power supply terminal and a ground terminal, respectively. The other transistors use the reverse polarity of the junction polarity shown in FIG. Also in this circuit, as in the case of FIG. 1, the second diode 19 is forwardly connected between the base of the output driving transistor 50 and the base of the second transistor 48.

The operation of this circuit is almost the same as in the case of FIG. That is, when the base voltage of the second transistor 48 rises and exceeds a predetermined level due to the temperature characteristic of the diode 11, the differential output transistor 40 is driven to invert the output of the output terminal 13 to notify the abnormal temperature. .
Further, when the diode 11 is open or short-circuited, the output drive transistor 50 is driven to invert the output of the output terminal 13 to notify the circuit failure.

[0056]

As described above, according to the inventions of claims 1 to 3, when the output voltage is smaller (or larger) than the reference voltage as a result of the comparison between the output voltage and the reference voltage. In addition to outputting the abnormality notification signal, the abnormality notification signal is output even when the output voltage is larger (or smaller) than the second reference voltage, so that not only the originally targeted abnormality is detected, but also the detected abnormality. It is possible to detect a failure of the circuit itself, and it is possible to effectively avoid an erroneous detection that a normal signal is output when the detection unit fails.

According to the invention described in claim 4, since one or more other diodes are connected between the base of the output drive transistor and the base of the second transistor, the output drive transistor is driven. It is possible to arbitrarily set the base voltage necessary for the detection, that is, the threshold value for detecting the failure of the detection circuit itself.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a temperature detection circuit according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of the temperature detection circuit of FIG.

FIG. 3 is a circuit diagram showing a temperature detection circuit according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an operation of the temperature detection circuit of FIG.

FIG. 5 is a circuit diagram showing a temperature detection circuit according to a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing a temperature detection circuit according to a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a conventional temperature detection circuit.

[Explanation of symbols]

 1,2,3,4 Resistance 5,15,45,61,62,63 Constant current source 6 Transistor 10,40 Differential output transistor 11 Diode 13 Output terminal 17 Output transistor 18,48 Second transistor 19 Second Diode 20,50 Output drive transistor 21,51 First transistor 23,24,53,81-86 Transistor 29,30,31,32 External terminal

Claims (4)

[Claims] 1. A voltage source whose output voltage changes, a means for comparing the output voltage of this voltage source with a predetermined reference voltage, and outputting an abnormality notification signal when the output voltage is lower than the reference voltage; An abnormality notification circuit comprising: means for outputting an abnormality notification signal when the voltage is higher than a second reference voltage which is higher than the reference voltage. 2. The abnormality notification circuit according to claim 1, wherein the voltage source is a diode whose forward voltage changes with temperature. 3. A base input comparator including a first transistor to which a predetermined reference voltage is applied to the base and a second transistor to which a terminal voltage of a diode that changes according to temperature is applied to the base. In the temperature detection circuit, a differential output transistor that is turned on / off according to a difference between a reference voltage applied to the base of the first transistor and a terminal voltage of the diode applied to the base of the second transistor, An output drive transistor, which is wired-OR connected to the differential output transistor with a collector and an emitter in common and driven by a diode terminal voltage applied to the base of the second transistor, and the differential output transistor or the output. Depending on the on / off operation of the drive transistor, the terminal of the diode A temperature detection circuit comprising: an output terminal that outputs a signal voltage indicating normality / abnormality of voltage. 4. The temperature detection circuit according to claim 3, wherein another one or a plurality of diodes are connected in series between the base of the output drive transistor and the base of the second transistor.