JPH0616540B2 - Thermal cutoff circuit of semiconductor integrated circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat cutoff circuit used for stopping operation or forcibly destroying a semiconductor integrated circuit such as a power amplification IC when abnormal heat is generated.

2. Description of the Related Art A power amplification IC or the like is provided with a heat cutoff circuit combined with four temperature detection circuit cutoffs in order to prevent the destruction of the IC due to abnormal heat generation of the IC due to malfunction or overload,
Normally, the base current of the power transistor in the output section is cut off to stop the operation.

In the case of performing complicated system control using a control device such as a microcomputer such as a VTR,
As shown in the figure, when a plug for supplying power to the apparatus is inserted into an outlet of a commercial AC power supply, the power supply circuit is always operated. That is, the AC power supply 2 is
The power is supplied from the power supply terminals 4A and 4B to the transformer 8 through the fuse 6, and the transformed output is rectified by the rectifier circuit 10 and then output from the output terminals 12 and 14, and
It is added to the stabilizing circuit 16 for stabilization. In this case, the stabilizing circuit 16 is composed of transistors 18, 20, a constant voltage element 22 and a resistor 24, the stabilized output is taken out from an output terminal 26, and in addition to a control circuit 28 composed of a microcomputer, for example. Has been. The control circuit 28 includes an operation changeover switch 3
0 is provided.

In a device using such a power supply circuit, the AC power supply 2 applied to the device itself is always maintained in a supply state, and the DC voltage is cut off by operating the operation switching switch 30. this is,
The power cannot be cut off regardless of the operating status of the device.The power switch controls the power supply via a microcomputer so that all functions are stopped or hibernated to turn off the power. ing.

In addition, the power supply for the motor drive circuit, the power supply for the plunger drive circuit, etc. and the timer display, etc.
The unstabilized output generated at 2 and 14 is used to keep the power always on. When stabilized, a large-capacity stabilized power supply circuit is required and the cost becomes high. Therefore, an unstabilized output is usually used.

Problems to be Solved by the Invention When a semiconductor integrated circuit such as a power IC installed in a device that is always energized as described above fails, an abnormal current flows and heat is generated, resulting in damage or overheating of the device. It may cause a fire. In particular, the more difficult an integrated circuit is to be destroyed, the more it tends to continue abnormal heat generation when it is destroyed, and as the destruction strength increases, the harmful effects such as the destruction of important parts other than the semiconductor integrated circuit surface.

For example, when a power transistor in a semiconductor integrated circuit is broken, control becomes ineffective, there is no power switch like a VTR (via a control means such as a microcomputer), and there is a risk of fire if it is always energized. .

Further, these breakdowns are caused by an abnormal current flowing through the semiconductor layers forming the semiconductor integrated circuit, and do not result in a complete short circuit. Excessive current does not flow as much as the power fuse is blown, and even if a fuse is used, sufficient protection cannot be achieved. For example, due to surge voltage, etc.
When exceeding the (AREA OF SAFETY OPERATION: safe operation area), destruction occurs on the order of microseconds (10 ^-6 seconds), while abnormal heat generation occurs only in an extremely narrow area and heat is distributed to the entire semiconductor integrated circuit. It takes the order of milliseconds (10 ^-3 seconds) to transmit, and of course, it cannot be protected by heat detection before destruction.

If an abnormal current continues to flow after the destruction and heat is generated, it is impossible to stop the abnormal heat generation by the conventional method of cutting off the drive signal.

In view of this, the present invention detects a heat generation temperature of a semiconductor integrated circuit such as a power IC and stops the operation of the semiconductor integrated circuit according to the heat generation temperature or forcibly destroys the semiconductor integrated circuit to install the semiconductor integrated circuit. It is an object of the present invention to provide a heat cutoff circuit for a semiconductor integrated circuit that protects a circuit device that is provided.

Means for Solving the Problems That is, the heat cutoff circuit of the semiconductor integrated circuit of the present invention is
A semiconductor integrated circuit including a main circuit portion (36) having a circuit element (power transistor 54) whose operation is to be forcibly stopped or destroyed at the time of an abnormality, and a first integrated circuit which is set at an arbitrary position of this semiconductor integrated circuit. An active element (transistor 40, Zener diode 118) is installed at the temperature detection point, and the heat generation temperature at the first temperature detection point is the first through the active element.
And a first temperature detection circuit (32, 320) for detecting that the temperature is equal to or higher than the reference temperature of the semiconductor integrated circuit.
An active element (transistor 52, 130) is installed at a second temperature detection point set other than the temperature detection point, and the heat generation temperature at the second temperature detection point is set to the first temperature detection point through the active element.
Second temperature detection circuit (34, 340) for detecting that the temperature is equal to or higher than the second reference temperature set higher than the reference temperature of
And when the first temperature detection circuit detects a heat generation temperature equal to or higher than the first reference temperature, the temperature detection output is received and an operation stop output is added to the circuit element to stop the operation of the main circuit. First transistor (108, 110)
When the second temperature detection circuit detects a heat generation temperature equal to or higher than the second reference temperature, the temperature detection output is received and an excessive current is caused to flow through the circuit element to destroy the circuit element to cause the main circuit to operate. It is characterized in that it is composed of the second transistors (112, 114) for stopping the operation of the circuit section.

Operation Therefore, according to the present invention, two temperature detection points of the first and second temperature detection points are set on the semiconductor integrated circuit, and the first temperature detection point is set.
Detects the heat generation temperature of the temperature detection point of the first reference temperature or more and stops the operation of the semiconductor integrated circuit, and detects the heat generation temperature of the second reference temperature or more of the second temperature detection point. A wiring conductor such as a gold wire of a semiconductor integrated circuit is melted and forcibly destroyed. That is, in order to prevent the semiconductor integrated circuit from abnormally generating heat and breaking due to abnormal usage conditions such as load short-circuit, motor lock, and abnormal overvoltage application, the chip temperature in the semiconductor integrated circuit is detected and operation is stopped. In addition, even after the operation is stopped, if the abnormal heat generation state progresses and the chip temperature rises, it is determined that the semiconductor integrated circuit has lost its normal function, and it is forcibly destroyed. The semiconductor integrated circuit is released.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of a heat radiation blocking circuit of a semiconductor integrated circuit according to the present invention.

In FIG. 1, first and second temperature detection circuits 32,
34 and the main circuit portion 36 are formed of the same semiconductor integrated circuit, and the temperature detection circuit 32 is set at an arbitrary position such as in the vicinity of an element accompanied by heat generation of the semiconductor integrated circuit.
, And the temperature detection circuit 34 is installed at a second temperature detection point set at an arbitrary position such as in the vicinity of the first temperature detection circuit 32 or in the vicinity of other heat-generating elements. ing.

That is, the temperature detection circuit 32 connects a diode formed of an NPN type transistor 40 to the constant current source 38 between the positive side line to which power is supplied and the installation side line, and is shared with the emitter of the transistor 40. The resistors 42 and 44 for voltage division are connected between the base and collector, and the base of a transistor 46 as an active element for detecting temperature is connected to the voltage division point. Transistor 40
Is configured as a Zener diode with a common base / collector, and is installed so as to have opposite polarities between the positive line side and the ground line side, and uses the breakdown voltage between the base and emitter for Zener operation. Is getting

Further, the second temperature detection circuit 34 includes a resistor 4 for voltage division between the emitter and the base / collector of the transistor 40.
8 and 50 are connected, and the base of a transistor 52 as an active element for detecting temperature is connected to the voltage dividing point.

The temperature detection circuit 32 has, for example, 1
The first reference temperature given at 50 ° C. is set, and the temperature detection circuit 34 is set at a second reference temperature of 200 ° C. which is higher than the first reference temperature, which is an operation start point. These temperature settings are set by resistors 42, 44 or resistor 4
The resistance ratio can be set to 8 or 50.

The main circuit device 36 includes a power transistor 54 as a circuit element installed in the main circuit section 36 according to the output of the first temperature detection circuit 32, that is, a circuit element that should be forcibly stopped or destroyed in an abnormal state. Together with the operation stop circuit 56 that stops the operation of the second temperature detection circuit 34, an excessive current is caused to flow in the power transistor 54 to melt a wiring conductor such as a gold wire connected to the power transistor 54 to melt the semiconductor. A destruction circuit 58 is installed to destroy the integrated circuit itself.

The operation will be described based on the above configuration.

In the Zener diode configured to have the base / collector of the transistor 40 in common, the breakdown voltage BV _EBO between the base and the emitter is usually +2 m.
It has a temperature coefficient of V / ° C., and the forward voltage V _BE between the base and emitter of the transistors 46 and 52 is usually −2 mV /
It has a temperature coefficient of about ℃.

When the base-emitter voltage of the transistor 46 is V _BE , the conduction condition of the transistor 40 is given by V _BE ≦ BV _EBO (1), K is the voltage division ratio of the resistors 42 and 44, and the resistor 42, If the resistance value of 44 is R ₁ and R ₂ , then R ₂ / (R
₁ + R ₂ ).

V _BE = V _BE (25 ° C) + α ₁ · ΔTa (2) BV _BEO = BV _BEO (25 ° C) + α ₂ · ΔTa (3) where ΔTa is the temperature rise from 25 ° C, BV
_BEO (25 ° C.) and V _BE (25 ° C.) are BV _BEO and V _{BE at} 25 ° C., α ₁ is the temperature coefficient of V _BE −2 mV /
° C and α ₂ are the temperature coefficient of BV _BEO +2 mV / ° C.

(V _BE −K · BV _EBO ) ≦ (−α ₁ + K · α ₂ ) ΔT …… (4) ΔT ≦ (V _BE −K · BV _EBO ) (−α ₁ + K · α ₂ ) …… (5) Therefore, when the temperature ΔT is the above value, the transistor 4
6 becomes conductive.

Under the same conditions, the voltage division ratio of the resistors 48 and 50 is set to be larger than the voltage division ratio K, and the value corresponding to, for example, 200 ° C. is set, so that the transistor 52 can be made conductive.

The conduction signal of the transistor 46 is applied to the operation stop circuit 56, and the conduction of the transistor 46 causes the transistor 5 to be turned on.
4 stops operating and the conduction signal of transistor 52 is applied to destruction circuit 58. Due to the conduction of the transistor 52, an excessive current flows through the transistor 54,
The semiconductor integrated circuit is destroyed and the current path is shifted to the completely open state.

The temperature detecting circuits 32 and 34 operate only above the reference temperature and do not impair the operation of the main circuit portion 36 of the semiconductor integrated circuit.

FIG. 2 shows the magnitude of the fusing current with respect to the thickness of a gold wire used as a wiring conductor in a semiconductor integrated circuit.
Is the energization time 1 (sec), B is the energization time 100 (msec)
It is understood that the gold wire can be easily melted by passing an excessive current through the power transistor 54.

As described above, when the heat generation of the semiconductor integrated circuit is detected and its operation is stopped, and when the heat generation temperature rises and exceeds the second reference temperature, the wiring conductor is melted and cut off, so that the heat generation state can be surely released. It is possible to prevent a catastrophic state of a device in which a semiconductor integrated circuit is installed or a fire due to overheating.

In this embodiment, the temperature detecting transistor 46 and the operation stopping circuit 56 are formed by a common transistor, and the temperature detecting transistor 52 and the destruction circuit 5 are formed.
8 may be composed of a common transistor.

FIG. 3 shows a specific circuit configuration example in which the heat cutoff circuit of the semiconductor integrated circuit of the present invention is used in a semiconductor integrated circuit for forward / reverse drive of a motor, and the same parts as those of the embodiment shown in FIG. It is attached with a code.

In FIG. 3, the motor forward / reverse drive circuit 60 includes transistors 62, 64, 66, 68, 70, 72, 74,
76 and resistors 78, 80, 82, 84, 86, 88,
A motor 98 is connected to terminals 94 and 96 formed of collectors of the transistors 68 and 76, and a driving voltage Vcc from the unstabilized power supply between the power supply terminal 99 and the ground side terminal 100. ₁ is added, power supply terminal 1
02 and the ground-side terminal 100, a driving voltage Vcc ₂ is applied from a stabilized power supply, and the control input terminals 104, 10
A control signal for forward rotation or reverse rotation is added to 6.
For example, at the time of forward rotation, the control input is applied to the control input terminal 104, so that the transistors 70, 72, 66 and 68 are rendered conductive and a drive current is applied to the motor 98, and at the time of reverse rotation, the control input terminal 106 is controlled. Since the input is given,
The transistors 62, 64, 74 and 76 are turned on to supply a drive current to the motor 98, and the direction of the current flow of the motor 98 is switched to switch the rotation direction thereof.

Then, operation stop circuits 56A and 56B are installed between the bases of the transistors 66 and 74 and the ground side line, respectively, and in this embodiment, the operation stop circuit 56A includes the first transistor 108 and the operation stop circuit 56B. Is composed of the first transistor 110. Further, a destruction circuit 58A is installed between the bases of the transistors 62 and 68, and a destruction circuit 5A is formed between the bases of the transistors 70 and 76.
8B is installed. In the case of this embodiment, the destruction circuit 5
8A is composed of the second transistor 112, and the destruction circuit 58B is composed of the second transistor 114.

The temperature detection circuit 32 includes a transistor 116, a Zener diode 118 and resistors 120, 122, 124, 1
26, the conduction signal of the transistor 116 is transmitted via the transistor 128 to the transistors 108, 110.
Has been added to the base of.

The temperature detection circuit 34 is composed of a transistor 130 and resistors 132, 134 and 136, and a conduction signal of the transistor 130 is a transistor 138 and a resistor 14.
A transistor 112 through a switch circuit consisting of 0,
It has been added to the base of 114.

According to such a configuration, when the transistor 116 detects heat generation above the first reference temperature and becomes conductive, the transistors 108 and 110 become conductive, so that the transistor 66,
Since the base potential of 74 decreases and the transistors 66 and 74 become non-conductive, the supply of the drive current is released and the rotation of the motor 98 is stopped.

Further, when the transistor 130 detects that the heat generation continues and the heat generation temperature becomes equal to or higher than the second reference temperature, the transistors 112 and 114 become conductive, and the transistors 62, 68, 70, and 76 have an excessive base current. Flows in. As a result, the wiring conductors connected to the transistors 62, 68, 70, and 76 are melted and transferred to a completely open state, so that abnormal heat generation due to continuous abnormal current is prevented, and overheat or fire due to overheat occurs. It can be prevented.

Further, the operating conditions of the temperature detecting circuits 32 and 34 depend only on the temperature rise, and are set so as to be in the non-conducting state under the heat generated in the normal use state. It has no effect.

The operation stop circuits 56A and 56B and the destruction circuit 58
A and 58B may be composed of thyristors, and in this case, gate signals are supplied from the temperature detection circuits 32 and 34.

FIG. 4 shows another embodiment of the heat cutoff circuit according to the present invention. The same parts as those of the embodiment shown in FIG. 3 are designated by the same reference numerals.

The temperature detection circuit 320 includes transistors 116, 142,
Zener diode 118 and resistors 120, 122,
A transistor 142 is provided on the anode side of the Zener diode 118 of the temperature detection circuit 32 shown in FIG. 3, and resistors 122 and 124 are connected to the emitter side of the transistor 142. The conduction signal of is applied to the operation stop circuit 56C.

The temperature detection circuit 340 is composed of a transistor 130 and resistors 132, 134, 136, 144, and the conduction signal of the transistor 130 is applied to the destruction circuit 58C via a switch circuit composed of the transistor 143 and the resistor 144.

The operation stop circuit 56C is the multi-emitter transistor 14
6 and the destruction circuit 58C is composed of a multi-emitter transistor 148 and a resistor 150.

The main circuit section 360 includes transistors 154, 1
56 and resistors 158, 160, 162 and the like are installed in the control circuit, one of the emitters of the transistor 146 of the operation stop circuit 56C is connected to the connection point of the resistors 160, 162, and the destruction circuit is connected to the base of the transistor 156. One emitter of the 58C transistor 148 is connected.

The other emitters of the transistors 146 and 148 are used to stop the operation of a power transistor or the like (not shown), or for its excessive current.

With such a configuration, when the transistor 146 becomes conductive in response to the operation of the temperature detection circuit 320, the base potential of the transistor 156 decreases and the operation is stopped.

Further, the temperature detection circuit 340 operates and the transistor 14
When transistor 8 is turned on, transistor 156 is connected to transistor 1
An excessive base current is given from 48, and the transistor 1
54, 156 and gold wires connecting the electrodes are destroyed.

Also, in this way, the multi-emitter transistor 146,
By using 148, the operation of a plurality of power transistors can be stopped and the wiring conductor can be blown off at two or more places, and the safety factor can be increased.

As described above, according to the present invention, the heat generation temperature on the substrate of the semiconductor integrated circuit is different at two different positions without deteriorating the normal operating state that the semiconductor integrated circuit should achieve. By setting and detecting the second reference temperature at the same time, the protection operation by stopping or breaking the operation of the semiconductor integrated circuit is performed stepwise according to the heat generation temperature, so that the semiconductor integrated circuit is installed. It is possible to prevent damage due to overheating of the circuit device, and prevent a catastrophic destruction state such as a fire from occurring.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a heat cutoff circuit of a semiconductor integrated circuit of the present invention, FIG. 2 is an explanatory diagram showing a fusing current with respect to the thickness of a gold wire, and FIG. 3 is a semiconductor integrated circuit of the present invention. FIG. 4 is a circuit diagram showing a specific embodiment of the heat cutoff circuit, FIG. 4 is a circuit diagram showing another embodiment of the heat cutoff circuit of the semiconductor integrated circuit of the present invention, and FIG. 5 shows the configuration of a conventional control device. FIG. 32, 320 ... First temperature detection circuit 34, 340 ... Second temperature detection circuit 36 ... Main circuit portion 46, 52 ... Transistor (active element) 54 ... Power transistor (circuit element) 108, 110 ...... First transistor 112, 114 ...... Second transistor 118 ...... Zener diode (active element) 130 ...... Transistor (active element)

Claims (2)

[Claims] 1. A semiconductor integrated circuit having a main circuit section having a circuit element whose operation is to be forcibly stopped or destroyed in the event of an abnormality, and a first temperature detection point set at an arbitrary position of the semiconductor integrated circuit. A first temperature detecting circuit for detecting that the heat generation temperature at the first temperature detecting point is equal to or higher than a first reference temperature through the active element, and the first integrated circuit of the semiconductor integrated circuit. An active element is installed at a second temperature detection point set other than the temperature detection point, and the heat generation temperature at the second temperature detection point is set to the first temperature detection point through the active element.
A second temperature detection circuit that detects a second reference temperature that is set higher than the second reference temperature, and the first temperature detection circuit detects a heat generation temperature that is equal to or higher than the first reference temperature. A first transistor that receives the temperature detection output and adds an operation stop output to the circuit element to stop the operation of the main circuit unit; and the second temperature detection circuit that generates heat above the second reference temperature. When a temperature is detected, a second transistor that receives the temperature detection output and causes an excessive current to flow in the circuit element to destroy the circuit element and stop the operation of the main circuit portion is formed. And a heat cutoff circuit for a semiconductor integrated circuit. 2. The heat cutoff of the semiconductor integrated circuit according to claim 1, wherein the first temperature detection circuit or the second temperature detection circuit is configured by a transistor or a Zener diode. circuit.