JPH02202219A - Temperature detection circuit - Google Patents

Abstract

PURPOSE:To prevent the event of dispersion in the setting of ambient temperature at which a temperature detection signal is introduced by comparing a 1st voltage constant independently of a change in the ambient temperature and corresponding to a predetermined ambient temperature with a 2nd voltage corresponding to the ambient temperature directly by using a comparator. CONSTITUTION:A temperature detection circuit 11 is provided with a reference voltage generating circuit 12 generating a reference voltage VREG corresponding to a predetermined ambient temperature and independently of a charge in the ambient temperature, resistors R11, R12 connecting in series between the reference voltage VREG and ground, and a comparator A1 comparing a temperature dependent voltage VTEM with a voltage at a connecting point 17 between the resistors R11 and R12. The dispersion in the reverse saturation current IS causes an error in the temperature detection operation but the voltage appearing across the resistor R18 depends on the reverse saturation current IS. Thus, even when the dispersion exists, the event of causing an error in the temperature detection is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature detection circuit 1c11 for detecting temperature rise due to heat generation in, for example, a power semiconductor integrated circuit to prevent thermal breakdown of the semiconductor integrated circuit.

[Conventional technology]

For example, in power integrated circuits such as power supply circuits, the circuit may be thermally destroyed due to heat generation.To prevent this, the temperature of the integrated circuit is detected and when the temperature rises, the current is cut off to prevent heat generation. Suppression techniques are used. FIG. 5 is a block diagram showing the electrical configuration of such a conventional temperature detection circuit 1, and FIG. 6 is an electrical circuit diagram showing a specific example thereof. The temperature detection circuit 1 will be explained with reference to FIGS. 5 and 6.

The temperature detection circuit 1 corresponds to a predetermined ambient temperature 9 and includes a reference voltage generation circuit 2 that generates a reference voltage vREG without depending on changes in the ambient temperature, and a temperature detection circuit 2 that generates a reference voltage VREG within the reference voltage generation circuit 2 between the reference voltage V and ground. The base is connected between resistors R1 and R2 connected in series to EG, the collector is connected to a constant current source 3, the emitter is connected to a grounded transistor Q7, the base is connected to the collector of transistor Q7, and the emitter is It is configured to include a transistor Q8 which is grounded and whose collector outputs the temperature detection output TSD.

The reference voltage generation circuit 2 is supplied with a power supply voltage V. 0 is input.

Power supply voltage ■. 0 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the connection point between resistor R1 and reference voltage V.sub.1.

The collector of the REG transistor Q3 is connected to the emitter of the transistor Q1 whose collector is grounded via a constant current divider 4. The base of transistor Q3 is connected to the collector of transistor Q2 whose emitter is grounded via resistor R3 and the base of transistor Q1.

The emitter of the transistor Q3 is connected via a resistor R7 to the collector of a transistor Q6 whose base and collector are electrically connected, and the emitter of the transistor Q6 is connected via a parallel resistor R4 and R5 to a transistor Q4 constituting the current mirror circuit 5. ．． Each is connected to the collector of Q5. Transistor Q4. The emitters of Q5 are respectively grounded via a resistor R6 and directly. transistor Q
4 through capacitor C1 and directly,
Connected to the collector and base of transistor Q2, respectively.

In this prior art, the reference voltage V REG is
The base voltage of the transistor 07Φ divided by 2 is compared with the base-emitter voltage V of the transistor Q7, and the magnitude of the base-emitter voltage VBE7, which depends on the ambient temperature, is measured. There is.

The operation of the conventional technology will be described below. Assuming that the transistor Q4 has an emitter area of Nm with respect to the transistor Q5, the voltage V1 generated across the resistor R6 is expressed as follows: k: Boltzmann constant q: electron charge T: absolute temperature. Therefore, if the current flowing through the transistor Q2 is 12, the voltage v2 at the connection point 6 between the resistors R4 and R5 is R6q q lS (2) I: reverse saturation current. The first term on the right side of equation (2) above represents the voltage drop across the resistor R4, and the second term represents the base-emitter voltage of the transistor Q2. The first term on the right side of equation (2) above is proportional to temperature, and the second term is 1. is proportional to temperature,
Since it is inversely proportional to temperature, the value of the right hand side of equation (2) is the well-known bandgi 1! The constant voltage (about 1.25V) is loud. In addition, the voltage drop due to the resistor R7 and the transistor Q6 is approximately 161 (direct). Therefore, the reference voltage
, 6 is approximately 2 whose value does not change depending on temperature changes.
．． It becomes a constant voltage of 5v.

The base-emitter voltage VB[7 of the transistor Q7 when the transistor Q7 is turned on at the set temperature t is determined by 'J Is . At this time, the transistor Q8 is cut off, and the temperature detection signal TSD becomes a high level or high impedance state, and in this sense, the temperature detection signal TSD
will be taken out. At this time, the base voltage of the transistor Q7 is the reference voltage VRE. is the value divided by resistor R1, [2], and according to equation (2), there is almost no variation from circuit to circuit and it is constant, but the reverse saturation current I in equation (3) is diffused. This depends on the carrier concentration and the concentration of minority chirelia, and is determined by the manufacturing conditions of the integrated circuit. Therefore, no matter how much the accuracy of the reference voltage VREG is increased, the temperature setting of the temperature detection circuit 1 remains unchanged between the base and emitter of the transistor Q7. It depends on the voltage V8[7.

(Problems to be Solved by the Invention) Since the conventional temperature detection circuit 1 is configured as described above, the reverse saturation current I8 shown in equation (3) above varies depending on the manufacturing conditions, and the temperature detection circuit 1 is Variation occurs in the temperature detected by the circuit 1, and such a temperature detection circuit 1
In some cases, it may not be possible to achieve the effect of preventing thermal damage to integrated circuits, which is proposed in the following.

This invention was made to solve the above-mentioned problems, and Is!, which causes variations in the detected temperature!
It is an object of the present invention to provide a temperature detection circuit that prevents the above and eliminates the need for complicating the circuit configuration.

[Means to solve the problem]

The temperature detection circuit according to the present invention includes a first voltage generating means that generates a first voltage that corresponds to a predetermined ambient temperature and is constant regardless of changes in the ambient temperature, and a second voltage that corresponds to the ambient temperature. The first voltage from the first voltage generating means and the second voltage from the second voltage generating means are compared, and when a predetermined magnitude relationship is established, A comparator for deriving a temperature detection signal is provided.

[Effect]

The comparator in this invention compares a first voltage that corresponds to a predetermined ambient temperature and is constant regardless of the ambient temperature and a second voltage that corresponds to the ambient temperature, and when a predetermined magnitude relationship is established. A temperature detection signal is derived.

(Embodiment) FIG. 1 is a block diagram showing the basic configuration of a temperature detection circuit 11 according to an embodiment of the present invention, and FIG. 2 is an electric circuit diagram showing a specific example thereof. With reference to Figures 1 and 2,
This example will be explained.

The temperature detection circuit 11 is provided, for example, in a power integrated circuit such as a power supply circuit, and is configured to detect ambient temperature in order to prevent thermal breakdown due to heat generation of integrated circuit elements.

The temperature detection circuit 11 generates a reference voltage vREG that corresponds to a predetermined ambient temperature and is independent of changes in ambient temperature.
a reference voltage generation circuit 12 that generates a reference voltage vREG;
and ground, and a comparator A1 that compares the temperature-dependent voltage V1° with the voltage at the connection point 17 between the resistors R11 and R12.

The reference voltage generation circuit 12 is supplied with a power supply voltage V. 0 is input. The power supply voltage ■CC is connected to the collector of the transistor Q13, and the emitter of the transistor Q13 is connected to the resistor R11 and IQ! Connected to the connection point with voltage V. The collector of transistor Q13 is connected via constant current source 14 to the emitter of transistor Q11 whose collector is grounded. The base of transistor Q13 is connected to the collector of transistor Q12 whose emitter is grounded via resistor R13 and the base of transistor Q11.

The emitter of transistor Q13 is connected via resistor R17,
The base and collector are connected to the collector of a conductive transistor Q16, and the emitter of the transistor Q16 is
Current mirror circuit 1 via parallel resistors R14 and R15
Transistor Q14.5 constituting transistor Q14. Each is connected to the collector of Q15. Transistor Q14. The emitters of Q15 are respectively grounded via resistor R16 and directly. The collector of transistor Q14 is connected via capacitor C11 and directly to the collector and base of transistor Q12, respectively.

Transistor Q14. The base of Q15 is the transistor Q
21, the emitter of transistor Q21 is grounded via resistor R20, and the collector is connected to resistor 1.
8 to the reference voltage RE6.

Comparator A1 includes a transistor Q19 whose base is connected to node 16 between the collector of transistor Q21 and resistor R18, and node 1 between resistors R11 and R12.
A transistor Q20 whose base is connected to 7 and a resistor R
A transistor Q18 whose collector is connected to the base of a transistor Q20 which is grounded through a transistor Q19 is included. The transistor Q19. A constant current source 13 is connected to the emitter of Q20.

The operation of the temperature detection circuit 11 will be explained below. When the voltage at the connection point 16 is expressed as a voltage drop V3 from the reference voltage vREG at a certain temperature t, it becomes k(T+t) R18 a R20 from the above equation (1). Furthermore, from the second equation above, the voltage at the connection point 17 has a constant value regardless of the temperature. This constant value is the resistance R11,
It can be freely set by changing the partial pressure ratio of R12. Now, the voltage at the connection point 17 is at a set temperature t, which is predetermined as the above-mentioned certain temperature t. The voltage dividing ratio of the resistors R11 and R12 is set so as to be equal to the voltage 3 in the above equation (4) when the voltage is adopted.

The detected temperature t is the set temperature t. less than transistor Q1
9. The base potential of Q20 is higher in transistor Q19 when viewed from the ground potential side, so the current [4] of constant current source 13 flows through transistor Q20, transistor 018 becomes conductive, and temperature detection signal TSD is output. Ru. Also, the detected temperature t is the set temperature t. If it is more than
Current I4 flows to ground through transistor Q19, and transistor 018 is cut off. In this way,
The basic operation of the temperature detection circuit 11 is realized.

On the other hand, in such a temperature detection circuit 11, there are variations from element to element. In the conventional example, the variation in the reverse saturation current IS causes the difference in temperature detection operation Mi, as shown in equation (3), but in the present example, the voltage appearing across the resistor R18 is As shown in equation (4), it is determined regardless of the reverse saturation current I. Therefore, even if the above-mentioned variations exist, errors in temperature detection operation can be prevented.

FIG. 3 is a block diagram showing the basic configuration of a temperature detection circuit 21 according to another embodiment of the present invention, and FIG. 4 is an electrical circuit diagram showing a specific example of the temperature detection circuit 2. This embodiment will be described with reference to Figures 3 and 4.This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals.The noteworthy points of this embodiment are as follows. Hysteresis is set in the comparator A1 to provide stability to the temperature detection operation.

The collector of transistor Q19 of comparator A1 is resistor R2.
1 to ground. When a resistor R24 is connected between the resistor R11 and the reference voltage V, a transistor Q23 having an emitter and a collector connected to both ends of the resistor R24 is provided together with EG. Further, the collector of the transistor Q22 whose base is connected to the collector of the transistor Q19 is connected to the resistors R22 and R23.
The reference voltage vREo is connected in this order. The base of the transistor Q23 is connected between resistors R22 and R23.

The emitter of the transistor Q22 is grounded.

In such a temperature detection circuit 21, the detected temperature t is the set temperature t. When this happens, the transistor Q18 switches from the conductive state to the cutoff state as described above, but at this time, the current 14 flows through the transistor Q19 and the resistor R21, and the transistor Q22 becomes conductive. As a result, the base potential of transistor Q23 drops, and transistor 023 becomes conductive. At this time, connection point 17
The change in voltage ΔV is expressed as C[23...(4) where V is the saturation voltage of transistor Q23. Further, the temperature coefficient of the voltage generated across the resistor R18 is as follows (5). Here, the variable t. is the set temperature mentioned above. Therefore, from the fourth equation and the fifth equation, ΔV/K becomes the hysteresis width in terms of temperature of the temperature detection circuit 21 of this embodiment.

In this embodiment, the same effects as those described in the previous embodiments can be achieved, and since hysteresis is set for the detection operation, it is possible to prevent the temperature detection outputs 1 to SD from changing unnecessarily. becomes stable.

In each of the above embodiments, the base voltage of the transistor Q19, which changes in proportion to the temperature, is compared with a constant voltage that is not affected by the temperature, but as another embodiment, the comparator A1
Transistor Q12 which inverts the phase of and is inversely proportional to temperature.
The temperature detection operation may be performed by comparing the base-emitter voltage of the sensor with a constant voltage that is not affected by the temperature.

In this case, the reference voltage V includes a term consisting of the base-emitter voltage of the transistor Q12 in the second term as EG shown in equation (2), and when the base-emitter voltage of the transistor Q12 varies, the reference voltage V VREG
The temperature detection output T
SD becomes constant.

〔Effect of the invention〕

As explained above, according to the present invention, a first voltage corresponding to a predetermined ambient temperature and constant regardless of changes in the ambient temperature and a second voltage corresponding to the ambient temperature are connected to each other by a comparator. Since direct comparison is made using This has the effect of ensuring avoidance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a temperature detection circuit according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram showing a specific example of the temperature detection circuit, and FIG. 3 is a block diagram showing a basic configuration of a temperature detection circuit according to an embodiment of the present invention. FIG. 4 is a block diagram showing the basic configuration of an example temperature detection circuit. FIG. 4 is an electric circuit diagram showing a specific example of the temperature detection circuit. FIG. 5 is a block diagram showing the basic configuration of a conventional temperature detection circuit. FIG. 6 is an electric circuit diagram showing a specific example of the temperature detection circuit. In the figure, 11.21 is a temperature detection circuit, 12 is a reference voltage generation circuit, A1 is a comparator, and 2 is a reference EG standard voltage. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A first voltage generating means that generates a first voltage that corresponds to a predetermined ambient temperature and is constant regardless of changes in the ambient temperature; and a second voltage generating means that generates a second voltage that corresponds to the ambient temperature. voltage generating means; a first voltage from the first voltage generating means; and a first voltage from the first voltage generating means;
A temperature detection circuit comprising a comparator that compares the second voltage from the voltage generating means and derives a temperature detection signal when a predetermined magnitude relationship is established.