JP2009232513A - Protection circuit, semiconductor device, and electric apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection circuit having both proper functions of overcurrent protection and overtemperature protection. <P>SOLUTION: The protection circuit includes: a first resistor for detecting a current applied to a circuit to be protected as a voltage; a reference voltage generating circuit for generating a reference voltage; an overcurrent detection circuit having an output to become high impedance when the voltage does not exceed the reference voltage and an output to become a predetermined voltage when the voltage exceeds the reference voltage; an overtemperature detection circuit including a temperature detection element having a resistance value varying in accordance with a temperature, a second resistor connected in series to the temperature detection circuit, a transistor having a control electrode connected in common to the output of the overcurrent detection circuit and to a connection point between the temperature detection element and the second resistor, operating in response to the voltage of the connection point when the output of the overcurrent detection circuit becomes high impedance, and operating in response to the predetermined voltage when the output of the overcurrent detection circuit becomes the predetermined voltage; and a control circuit for controlling so as to protect the circuit to be protected in response to the output of the transistor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a protection circuit, a semiconductor device, and an electric device.

 When a semiconductor device operates, it generates heat due to internal loss, and as a result, there are cases in which drive capability is deteriorated, various characteristics are deteriorated, and in the worst case, destruction occurs. As described above, heat generation is a factor that causes a decrease in performance, safety, and reliability of the semiconductor device. Therefore, it is necessary to release the heat to the outside and operate the semiconductor device within the allowable operating temperature range. Therefore, a mounting technique called an insulating metal substrate technique has been proposed (for example, see Patent Document 1 shown below).

 Insulating metal substrate technology mounts circuit components such as semiconductor devices on a metal substrate with high thermal conductivity (for example, an aluminum plate) whose surface is coated with insulating resin, etc., so that the heat generated by the circuit components can be reduced. It is a mounting technology that dissipates heat through the board. A conductive pattern is formed on the surface of the metal substrate, and circuit components necessary for realizing a desired function are electrically connected in accordance with the conductive pattern. That is, a circuit module (semiconductor device) that realizes a desired function by mounting circuit components on a metal substrate with high density can be realized by the insulated metal substrate technology.

Insulated metal substrate technology has features such as high heat dissipation and high-density mounting as described above, and efficiently dissipates the heat concentrated by mounting circuit components at high density on the metal substrate via the metal substrate. be able to. For this reason, the insulated metal substrate technology is suitable as a mounting technology for power electronics devices that handle large currents and large powers, such as inverter circuits used in air conditioners (air conditioners), washing machines, refrigerators, and the like. .
JP 2003-319546 A

 Incidentally, in an inverter circuit, a power semiconductor device such as a power MOSFET or IGBT is generally used as a switching element for driving an inverter load of a three-phase motor. A power semiconductor device has excellent features such as a high breakdown voltage, a large current, and a high-speed switching as compared with a normal semiconductor device such as a bipolar transistor, but has a drawback that an allowable short-circuit time is short.

 For this reason, when an abnormality such as a three-phase motor lock occurs, the power semiconductor device may be destroyed in a very short time. Therefore, when the current flowing through the power semiconductor device becomes an overcurrent exceeding a predetermined current, it is necessary to appropriately provide an overcurrent protection function for stopping the operation of the inverter circuit.

 Further, when the temperature of the inverter circuit exceeds the predetermined temperature and is overheated, there is a risk that circuit components constituting the inverter circuit such as a power semiconductor device are destroyed. For this reason, when the temperature of the inverter circuit becomes an overtemperature exceeding a predetermined temperature, it is necessary to appropriately provide an overtemperature protection function for stopping the operation of the inverter circuit.

  In the case of circuit modules using insulated metal substrate technology, it is necessary to change the size of the metal substrate when the mounting density of the main functional circuits is originally high when the limited board space is effectively utilized. There will be a cost increase. In addition, in the case of limit design, it is difficult to add circuit components for optional functions of main functional circuits. Therefore, in the case of a circuit module, it is difficult to provide both an overcurrent protection function and an overtemperature protection function.

  A main invention for solving the above problem is that a first resistor that detects a current flowing through a protected circuit as a voltage, a reference voltage generation circuit that generates a reference voltage, the voltage is compared with the reference voltage, and the voltage When the voltage does not exceed the reference voltage, the output becomes high impedance, and when the voltage exceeds the reference voltage, the output becomes a predetermined voltage, and the temperature detection element whose resistance value changes according to the temperature, A second resistor connected in series to the temperature detection element, and a control electrode connected in common to an output of the overcurrent detection circuit and a connection point of the temperature detection element and the second resistance, the overcurrent detection circuit When the output of the overcurrent detection circuit becomes a high impedance, the circuit operates according to the voltage at the connection point regardless of the output of the overcurrent detection circuit. A protection circuit comprising: an overtemperature detection circuit including a transistor that operates in accordance with the predetermined voltage regardless of a pressure; and a control circuit that controls to protect the protected circuit in accordance with an output of the transistor. is there.

  According to the present invention, it is possible to provide a protection circuit, a semiconductor device, and an electrical device that are appropriately provided with both an overcurrent protection function and an overtemperature protection function.

<<< Devices using circuits with overcurrent and overtemperature protection functions >>>
=== Inverter circuit ===
FIG. 1 shows a case of an inverter device 100 using an inverter circuit 120 having both an overcurrent protection function and an overtemperature protection function.
The overcurrent protection function of the present embodiment is to stop the three-phase motor 130 when the current to be detected exceeds a predetermined current due to the lock of the three-phase motor 130 or the like, and the overcurrent of the switching circuit 121 This function prevents destruction and failure of the three-phase motor 130.
The over-temperature protection function of the present embodiment is the same as the over-current protection function when the temperature to be detected exceeds the predetermined temperature. This function prevents a failure of the three-phase motor 130.

  The inverter device 100 of this embodiment is used for power electronics devices such as an air conditioner, a washing machine, and a refrigerator, and converts AC power into AC power of another magnitude, frequency, and phase according to the inverter load. It is a device. Specifically, the inverter device 100 converts the AC voltage of the three-phase AC power source 105 including the R-phase coil, the S-phase coil, and the T-phase coil into a DC voltage by the converter circuit 110, and then converts the AC voltage by the inverter circuit 120. An AC voltage for driving an inverter of a three-phase motor 130 (inverter load) having a U-phase coil, a V-phase coil, and a W-phase coil is generated based on the DC voltage.

The inverter circuit 120 is provided as an integrated circuit (first integrated circuit) including at least a V + terminal, a V− terminal, a U terminal, a V terminal, and a W terminal.
A DC voltage changed by the converter circuit 110 is applied between the V + terminal and the V− terminal. A smoothing capacitor CX is connected between the V + terminal, the V− terminal, and the converter circuit 110, and a DC voltage applied from the converter circuit 110 between the V + terminal and the V− terminal is stabilized by the smoothing capacitor CX. To do.
The U terminal, V terminal, and W terminal are connected to the U phase coil, V phase coil, and W phase coil of the three-phase motor 130, respectively.

  The inverter circuit 120 includes a switching circuit 121 (protected circuit), shunt resistors Ru, Rv, Rw (first resistor), RC filters 122a, 122b, 122c, an overcurrent / overtemperature detection circuit 123, and a driver circuit. 125 (control circuit). The configuration of the inverter circuit 120 other than the switching circuit 121 is an embodiment of the protection circuit according to the claims of the present application.

  The switching circuit 121 includes switching elements Q1 to Q6 and regenerative diodes D1 to D6 connected in reverse parallel to the switching elements Q1 to Q6, and supplies a DC voltage applied via the V + terminal and the V− terminal as a power source. Operates as a voltage. As the switching elements Q1 to Q6, power semiconductor devices such as power MOSFETs and IGBTs are employed.

  The switching elements Q1, Q2, and Q3 are provided on the current discharge side (V + terminal side) and are called source transistors. The switching elements Q4, Q5, Q6 are provided on the current suction side (V-terminal side) and are called sink transistors. Switching elements Q1 and Q4 are connected in series, and the connection point of switching elements Q1 and Q4 is connected to the U terminal. The switching elements Q2 and Q5 are connected in series, and the connection point of the switching elements Q2 and Q5 is connected to the V terminal. The switching elements Q3 and Q6 are connected in series, and the connection point of the switching elements Q3 and Q6 is connected to the W terminal.

  The shunt resistors Ru, Rv, and Rw are overcurrent detection resistors that are provided between the emitters of the switching elements Q4, Q5, and Q6 and the V-terminal, respectively, and are used for overcurrent detection in the overcurrent / overtemperature detection circuit 123. is there. Since the overcurrent detection resistor needs to detect an accurate current with respect to the actual load even when a large current flows, the shunt resistors Ru, Rv, and Rw having a small voltage drop and loss are employed. .

  As the overcurrent detection method in this embodiment, as shown in FIG. 2A, one shunt resistor Rs provided in common at the detection node on the V-terminal side of the switching elements Q4, Q5, Q6 is used. Instead of the method (hereinafter referred to as “one shunt method”), as shown in FIG. 2B, three shunt resistors provided at the detection nodes on the V-terminal side of the switching elements Q4, Q5, and Q6, respectively. A system using Ru, Rv, and Rw (hereinafter referred to as “3-shunt system”) is employed.

  FIG. 3 shows an example of a detected current waveform in each of the 1-shunt method and the 3-shunt method. In the case of the single shunt method, the combined current of the currents flowing through the switching elements Q4, Q5, and Q6 is detected by one shunt resistor Rs, and overcurrent protection is performed when the combined current exceeds the predetermined current. Is done. The combined current detected by the shunt resistor Rs has a rectangular waveform different from the sine waveform of the motor current flowing in each phase coil of the three-phase motor.

  On the other hand, in the case of the three shunt method, each current of the switching elements Q4, Q5, and Q6 is individually detected by the three shunt resistors Ru, Rv, and Rw, and any one of the detected currents is a predetermined current amount. Overcurrent protection is performed when the overcurrent exceeds. The current detected by each of the three shunt resistors Ru, Rv, Rw has a waveform similar to the sine waveform of the motor current flowing in each phase coil. Therefore, in the case of the three-shunt method, the motor current flowing through the three-phase motor 130 can be detected more accurately than in the case of the one-shunt method, and the accuracy of overcurrent protection can be improved.

  The RC filter 122a is a filter to which a voltage generated by a current flowing through the shunt resistor Ru is applied, and a voltage Vu obtained by smoothing the voltage is output to the overcurrent / overtemperature detection circuit 123. The RC filter 122b A voltage generated by the current flowing through the shunt resistor Rv is applied and a voltage Vv obtained by smoothing the voltage is output to the overcurrent / overtemperature detection circuit 123. The RC filter 122c is connected to the shunt resistor Rw. Is applied to the voltage, and the voltage Vw obtained by smoothing this voltage is smoothed and output to the overcurrent / overtemperature detection circuit 123.

  Based on the voltages Vu, Vv, and Vw that have passed through the RC filters 122a to 122c, the overcurrent / overtemperature detection circuit 123 detects overcurrent for the overcurrent protection function, overtemperature detection for the overtemperature protection function, Is a circuit that integrally implements. The overcurrent / overtemperature detection circuit 123 outputs a high level detection signal DET when detecting an overcurrent or overtemperature in the inverter circuit 120. In other words, when the detection signal DET is at a low level, it represents a case where neither overcurrent nor overtemperature is detected. A detailed configuration example of the overcurrent / overtemperature detection circuit 123 will be described later.

  The driver circuit 125 outputs a control signal for controlling the rotational speed of the three-phase motor 130 to the switching circuit 121 in accordance with an instruction from a microcomputer or the like outside the inverter circuit 120. When the driver circuit 125 receives the low level detection signal DET from the overcurrent detection circuit 123, the driver circuit 125 has, for example, a phase difference of 120 degrees, and controls on / off of the switching elements Q1 to Q3. Three pulse width modulated first rectangular waves, and three pulse width modulations that are generally 180 degrees out of phase with respect to the first rectangular waves and control on / off of the switching elements Q4 to Q6 The control signal (each base signal of switching element Q1-Q6) which consists of the 2nd rectangular wave which was made is output.

  When the driver circuit 125 receives the high level detection signal DET from the overcurrent / overtemperature detection circuit 123, the driver circuit 125 outputs a control signal for turning off all the switching elements Q1 to Q6. Thereby, the overcurrent protection function for the switching circuit 121 is executed. Note that the control signal when the high-level detection signal DET is output from the overcurrent / overtemperature detection circuit 123 is not limited to turning off all the switching elements Q1 to Q6, and the switching elements Q1 to Q6 are overcurrent. Any signal may be used as long as it can be controlled to the extent that it can be protected from destruction.

  FIG. 4 shows the waveforms of the gate signals of the switching elements Q1 to Q6 in the case of the three-phase 120 degree energization method.

=== Overcurrent / Overtemperature detection circuit ===
A detailed configuration example of the overcurrent / overtemperature detection circuit 123 is shown in FIG. The overcurrent / overtemperature detection circuit 123 includes a reference voltage generation circuit 1231, an overcurrent detection circuit 1232, and an overtemperature detection circuit 1234.

 The reference voltage generation circuit 1231 generates a reference voltage Vref to be compared with each of the voltages Vu, Vv, and Vw supplied from the RC filters 122a to 122c and supplies the reference voltage Vref to the overcurrent detection circuit 1232. The reference voltage generation circuit 1231 includes resistors R0 and R1 connected in series between the power supply voltage VCC and GND, and a capacitor C0 connected to a connection point of the resistors R0 and R1. The power supply voltage VCC is taken out from the first power supply line 1235 connected to the terminal of the resistor R0 on the power supply voltage VCC side. Further, the reference voltage Vref is taken out from the second power supply line 1236 connected to the terminal on the resistor R1 side of the resistor R0. The capacitor C0 maintains the level of the reference voltage Vref at the connection point of the resistors R0 and R1. The power supply voltage VCC is supplied to both the overcurrent detection circuit 1232 and the overtemperature detection circuit 1234 via the first power supply line 1235. The reference voltage Vref is supplied to the overcurrent detection circuit 1232 via the second power supply line 1236.

 The overcurrent detection circuit 1232 compares the voltages Vu, Vv, and Vw with the reference voltage Vref supplied from the reference voltage generation circuit 1231, respectively, so that an overcurrent has flowed in any of the shunt resistors Ru, Rv, and Rw. This is a circuit for detecting whether or not. The overcurrent of each of the switching elements Q4 to Q6 is detected as a logical sum. The overcurrent detection circuit 1232 includes three open collector output comparators 1233a, 1233b, and 1233c, and a capacitor C1 connected to the first power supply line 1235.

 In the open collector output comparator 1233a, the reference voltage Vref is applied to the + terminal from the reference voltage generation circuit 1231 via the second power supply line 1236, and the voltage Vu output from the RC filter 122a is applied to the − terminal. The open collector output comparator 1233a operates with the power supply voltage VCC supplied from the reference voltage generation circuit 1231. When the voltage Vu is lower than the reference voltage Vref, the output UO of the open collector output comparator 1233a becomes high impedance, and when the voltage Vu is higher than the reference voltage Vref, the output UO of the open collector output comparator 1233a becomes Low level.

 The open collector output comparators 1233b and 1233c have the same configuration as the open collector output comparator 1233a except that the voltages Vv and Vw are applied to the negative terminal. The comparison signals UO, VO, WO of the open collector output comparators 1233a, 1233b, 1233c are connected to the connection point X by wired OR. A synthesized output SO obtained by synthesizing the comparison signals UO, VO, WO from the connection point X is taken out and supplied to the base of the PNP bipolar transistor B10 in the overtemperature detection circuit 1234.

  FIG. 6 shows a circuit configuration example of the open collector output comparator 1233 (1233a, 1233b, 1233c). The open collector output comparator 1233 includes current sources I0 to I2, a differential amplifier circuit 1238 composed of bipolar transistors B0 to B5, a current source I3, and an output circuit 1239 composed of bipolar transistors B6 and B7. Become.

 Input + IN and input −IN of the differential amplifier circuit 1238 are terminals to which reference voltages Vru, Vrv, Vrw and voltages Vu, Vv, Vw are applied, respectively. In the differential amplifier circuit 1238, the current source I1 is distributed to the bipolar transistors B1 and B2 according to the voltage levels of the input + IN and the input −IN. When the voltage of the input + IN is larger than the voltage of the input −IN, the current distributed to the bipolar transistor B2 becomes large. When the voltage of the input + IN is smaller than the voltage of the input −IN, the current is distributed to the bipolar transistor B2. Current is smaller.

 In the output circuit 1239, the voltage input to the base of the bipolar transistor B6 connected to the connection point O of the bipolar transistors B2 and B4 increases when the voltage of the input + IN is larger than the voltage of the input −IN. When the voltage at + IN is smaller than the voltage at input -IN, the voltage becomes smaller. Therefore, when the voltage input to the base of the output bipolar transistor B6 is large (when “input + IN voltage> input−IN voltage”), the bipolar transistor B7 is driven to turn off and the output OUT is high. Impedance. On the other hand, when the voltage input to the base of the bipolar transistor B6 is small (in the case of “input + IN voltage <input−IN voltage”), the bipolar transistor B7 is driven in the ON direction and the output OUT is substantially the voltage. It becomes VEE level.

 The capacitor C1 maintains the level of the power supply voltage VCC supplied from the reference voltage generation circuit 1231 and supplies it to the overtemperature detection circuit 1234.

 The over temperature detection circuit 1234 detects an over temperature of the inverter circuit 120. The over-temperature detection circuit 1234 has a temperature detection element R2 and a resistor R3 connected in series between the power supply voltage VCC and GND supplied from the first power supply line 1235, and a connection point Y between the temperature detection element R2 and the resistance R3. On the other hand, a PNP bipolar transistor B10 (transistor) having a base connected thereto, a capacitor C2 for preventing oscillation of the temperature detection element R2 provided in parallel with the temperature detection element R2, and a capacitor connected to the collector of the PNP bipolar transistor B10 C3 and a resistor R4 connected to a connection point Z between the PNP bipolar transistor B10 and the capacitor C3.

 The temperature detecting element R2 is, for example, a posistor or thermistor having a positive temperature characteristic in which the resistance value increases as the temperature rises. Further, the detection signal DET is taken out from the terminal opposite to the connection point Z of the resistor R4. Further, the capacitor C3 and the resistor R4 constitute an integration circuit when viewed from the output terminal side that outputs the detection signal DET, and play a role of suppressing spike-like noise or the like mixed from the output terminal.

  In the over temperature detection circuit 1234, when the temperature to be detected is equal to or lower than a predetermined temperature that is an index of over temperature, the voltage at the connection point Y determined by the resistance ratio of the temperature detection element R2 and the resistor R3 (= R3 / (R2 + R3)) is The PNP bipolar transistor B10 is set to a voltage level that does not turn on. In other words, the PNP bipolar transistor B10 switches from off to on according to the voltage level at the connection point Y determined by the resistance ratio between the first resistance value of the temperature detection element R2 and the second resistance value of the resistor R3 when the temperature is excessive.

 Therefore, when the temperature is equal to or lower than the predetermined temperature, the detection signal DET extracted from the connection point Z via the resistor R4 is at a low level corresponding to the GND level because the PNP bipolar transistor B10 is off.

 On the other hand, when the temperature to be detected is an overtemperature exceeding a predetermined temperature, the resistance value of the temperature detection element R2 increases, and the voltage at the connection point Y determined by the resistance ratio between the temperature detection element R2 and the resistance R3 decreases. As a result, the base input of the PNP bipolar transistor B10 decreases, the PNP bipolar transistor B10 is driven in the ON direction, and the capacitor C3 is charged by the power supply voltage VCC. In this case, the detection signal DET becomes a high level corresponding to the power supply voltage VCC.

 Incidentally, the connection point X of the overcurrent detection circuit 1232 and the connection point Y of the overtemperature detection circuit 1234 are connected by a signal line 1237. As a result, the detection signal DET becomes a logical sum (wired OR) of the detection result (synthesized output SO) of the overcurrent detection circuit 1232 and the detection result (voltage of the connection point Y) of the overtemperature detection circuit 1234. Hereinafter, this logical sum will be described.

 In the overcurrent detection circuit 1232, when the overcurrent is not detected, the composite output SO becomes high impedance. At this time, in the overtemperature detection circuit 1234, the PNP bipolar transistor B10 does not turn on / off in response to the combined output S0 supplied via the signal line 1237. Therefore, the detection signal DET indicates only whether or not an overtemperature is detected based on the temperature detected by the temperature detection element R2, regardless of the combined output SO from the overcurrent detection circuit 1232.

 On the other hand, when an overcurrent is detected by the overcurrent detection circuit 1232, the combined output SO is at a low level. At this time, in the overtemperature detection circuit 1234, the PNP bipolar transistor B10 is driven to turn on by the composite output SO supplied via the signal line 1237 regardless of the voltage at the connection point Y. Therefore, the detection signal DET indicates whether or not an overtemperature is detected based on the temperature detected by the temperature detection element R2, and whether or not an overcurrent is detected based on the combined output SO from the overcurrent detection circuit 1232. It will also indicate whether or not.

 As described above, when both the overcurrent protection function and the overtemperature protection function are mounted, a circuit for generating a logical sum of the output of the overcurrent detection circuit 1232 and the output of the overtemperature detection circuit 1234 is not added. The connection point X of the overcurrent detection circuit 1232 and the connection point Y of the overtemperature detection circuit 1234 are wired OR connected via the signal line 1237. As a result, it is possible to mount both the overcurrent protection function and the overtemperature protection function while suppressing the circuit scale of the inverter circuit 120.

 The control circuit 124 can perform both the overcurrent protection function and the overtemperature protection function only by providing an input port (input terminal) corresponding to the detection signal DET from the overcurrent / overtemperature detection circuit 123. It becomes. For this reason, the number of ports of the control circuit 124 can be saved, and the circuit scale of the control circuit 124 can be suppressed.

 In addition, when the three-shunt method is adopted, the circuit scale of the inverter circuit 120 is obtained by connecting the comparison signals UO, VO, and WO of the open collector output comparators 1233a to 1233c suitable for high impedance output to the connection point X by wired OR connection. It is possible to easily detect the overcurrents of the shunt resistors Ru, Rv, and Rw based on one combined output SO.

<<< Semiconductor device using insulated metal substrate technology >>>
=== Semiconductor Device ===
FIG. 7 is a diagram showing the structure of the semiconductor device 10 using the insulated metal substrate technology. 7A is a cross-sectional view of the semiconductor device 10, and FIG. 7B is a surface view of the semiconductor device 10. FIG. 8 is a perspective view of the semiconductor device 10 shown in FIG.

The case material 3 is formed with a square cylinder surrounded by four side walls 3A, 3B, 3C, 3D, and has an opening 20 on the lower side (in the direction toward C ′ of the paper surface CC ′ axis) and an upper side (paper surface). An opening 21 in the direction of C-C ′ axis toward C) is provided.
On the inside of the side walls 3 </ b> C and 3 </ b> D of the case material 3, a convex portion 22 facing the inside of the case material 3 is provided at a position slightly elevated from the opening 20. Further, on the inner side of the side walls 3C, 3D of the case material 3, the back surface on the side surface side of the second substrate 2 (surface in the direction toward the C ′ of the paper surface CC ′ axis) at a position slightly lowered from the opening 21. The contact part 23 which contacts is provided.
On the other hand, in order to secure the screw holes 24 inside the side walls 3A and 3B of the case material 3, they are brought into contact with the back surface of the second substrate 2 (the surface in the direction toward the C ′ of the paper surface CC ′ axis). A contact portion 25 and a separation portion 26 that separates from the second substrate 2 in the direction of the paper plane BB ′ axis are provided. Heat generated in the space between the second substrate 2 and the first substrate 1A is released to the outside through the separation portion 26. In order to obtain a circulating action, it is preferable that at least two spacing portions 26 are formed.

 The base substrate 1B and the first substrate 1A are made of a conductive material such as a material mainly composed of Cu, Al, or Fe, or an alloy thereof. Further, it is made of a material having excellent thermal conductivity, and may be an insulating material such as aluminum nitride or boron nitride. In general, Cu and Al are adopted from the viewpoint of cost, and both are conductive, and therefore, an insulation treatment is required. In the following description, it is assumed that the base substrate 1B and the first substrate 1A employ Al.

 A first substrate 1A having a size smaller than that of the base substrate 1B is fixed to the surface of the base substrate 1B (surface in the direction toward the C of the paper surface C-C ′ axis) by an insulating adhesive 27. The base substrate 1B and the front and back surfaces of the first substrate 1A are provided with an anodized film for preventing scratches.

 In the first substrate 1A, an insulating film 28 is coated on an anodized film on the surface, and a first conductive pattern 7 made of Cu is formed thereon. The first conductive pattern 7 includes an island, a wiring, an electrode pad, and the like. For example, an inverter circuit 120 including switching elements Q <b> 1 to Q <b> 6 as the power semiconductor device 4 is electrically connected to the island of the first conductive pattern 7. In addition, a diode, a resistor, a capacitor, and the like are mounted on the first substrate 1A.

 A lead fixing pad is provided on the side of the first substrate 1A (the surface on the A, A 'side of the paper surface A-A' axis), and the external lead 29 is fixed by a brazing material. The external lead 29 has such a length that it protrudes from the head of the case material 3 and is inserted into a through hole of a mounting board (not shown).

 The first substrate 1A fixed to the surface of the base substrate 1B is fitted into the opening 20 on the lower side of the case material 3 (the direction toward the C ′ of the paper surface C-C ′ axis). The inner walls of the side walls 3A, 3B, 3C, and 3D of the case material 3 are provided with L-shaped steps, and the side surfaces of the base substrate 1B (the surfaces on the A and A 'sides of the paper surface AA' axis and the paper surface B) -The surface on the B, B 'side of the B' axis) and the surface (the surface in the direction toward the C on the paper surface CC 'axis) come into contact with each other and are fixed. Therefore, the opening 20 is sealed by the first substrate 1A fitted to the case material 3. As described above, since the second substrate 2 is held by the side walls 3C and 3D of the case material 3, the first substrate 1A and the second substrate 2 are arranged in parallel in parallel.

 The second substrate 2 is made of a resinous substrate, and for example, a glass epoxy substrate called a printed substrate is preferable. At least one or more second conductive patterns 30 are formed on the surface of the second substrate 2 (the surface in the direction toward the C of the paper surface C-C ′ axis). Similar to the first conductive pattern 7, the second conductive pattern 30 includes islands, wirings, electrode pads, and the like. For example, an integrated circuit (second integrated circuit) 31 such as a microcomputer or a DSP (Digital Signal Processor) for controlling the operation of the inverter circuit 120 is electrically connected to one island of the second conductive pattern 30. Is done. Since it is desirable to avoid the influence of heat, the integrated circuit 31 such as a microcomputer or a DSP can be operated accurately by being disposed on a substrate different from the substrate on which the inverter circuit 120 is disposed. In addition, a transistor, a diode, a resistor, and a capacitor are mounted on the second substrate 2.

 Before the second substrate 2 is provided on the case material 3, a resin that completely seals the circuit components mounted on the first substrate 1A is provided by potting or the like. Moreover, resin which completely seals the circuit components mounted on the second substrate 2 is provided as necessary. A through hole 32 for inserting the external lead 29 is provided in the vicinity of the side of the second substrate 2. Through the through hole 32, the circuit mounted on the first substrate 1A and the circuit mounted on the second substrate 2 are electrically connected.

  The inverter circuit 120 shown in FIG. 1 can be realized as the semiconductor device 10 using the insulated metal substrate technology shown in FIGS. FIG. 9 is a diagram illustrating a mounting example of main circuit components of the semiconductor device 10. 9A is a diagram showing an example of mounting the first substrate 1A, and FIG. 9B is a diagram showing an example of mounting the second substrate 2. As shown in FIG. In this mounting example, it is assumed that the first board 1A is a metal board and the second board 2 is a printed board.

  As shown in FIG. 9A, at least an inverter circuit 120 is mounted on the first substrate 1A. Since the first substrate 1A is a metal substrate with good thermal conductivity, it is less necessary to consider variations in the temperature characteristics of the shunt resistors Ru, Rv, and Rw, and overcurrent protection can be performed appropriately. . The temperature detection element R2 is preferably arranged as close as possible to the switching circuit 121 and the driver circuit 125 that increase in temperature during operation. However, the first substrate 1A is a metal substrate having good thermal conductivity. Therefore, the temperature of the semiconductor device 10 can be accurately detected without significantly affecting the mounting position.

  Further, as shown in FIG. 9B, a control circuit 124 as an integrated circuit 31 such as a microcomputer or a DSP shown in FIGS. 7 and 8 is mounted on the second substrate 2. As described above, the control circuit 124 is the most important circuit component that controls the overall control of the semiconductor device 10, and therefore the second substrate 2 different from the circuit component mounted on the first substrate 1 </ b> A. It is preferable to mount on the side. As a result, the control circuit 124 is not affected by the temperature rise of the switching circuit 121 and the driver circuit 125 mounted on the first substrate 1A. The case material 3 does not necessarily have to hold the second substrate 2 on which the control circuit 124 is arranged together with the first substrate 1A. The control circuit 124 may be held by a case material (not shown) different from the case material 3.

  Further, considering the deformation of the case material 3 due to the thermal expansion of the first substrate 1A and the deformation of the second substrate 2 due to the heat generated from the circuit components mounted on the first substrate 1A, the first substrate 1A is considered. It is preferable to mount the circuit components by shifting from the center position where the second substrate 2 is most curved.

 As described above, since the circuit scale of the inverter circuit 120 is suppressed to have both the overcurrent protection function and the overtemperature protection function, it is easy to apply the insulated metal substrate technology. Furthermore, by utilizing high heat dissipation, which is another feature of the insulated metal substrate technology, the operation rate of the overtemperature protection function can be suppressed and the reliability of the inverter circuit 120 can be further improved.

=== Application Example of Semiconductor Device ===
A semiconductor device (hereinafter referred to as an inverter circuit module 60) is attached to, for example, an air conditioner outdoor unit 50 shown in FIG. FIG. 10 is a diagram showing the internal structure of the air conditioner outdoor unit 50 using the inverter circuit module 60.
The air conditioner outdoor unit 50 includes a fan 51, a frame 52, a compressor 53, a heat radiation fin 55, and an inverter circuit module 60.

 The fan 51 circulates air and has a heat exchanger on the back side (negative direction of the paper surface Y axis). The frame 52 is arranged adjacent to the fan 51 in parallel in the positive direction of the paper surface X axis. A compressor 53 is provided below the insole plate 52A of the frame 52 (the negative direction of the paper surface Z axis), and circuit components are mounted above the insole plate 52A of the frame 52 (the positive direction of the paper surface Z axis). A printed circuit board or the like is attached.

 Furthermore, the inverter circuit module 60 is mounted on the side wall plate 54 on the negative direction side of the X axis of the frame 52. The inverter circuit module 60 is attached so that the second substrate 2 side faces the side wall plate 54 of the frame 52. In addition, the radiation fins 55 are attached to the base circuit board 1B side of the inverter circuit module 60.

 The code | symbol 56 shown in FIG. 10 has shown air flow path AB produced | generated because air warms and raises. The grooves of the radiating fins 55 are provided in the direction along the air flow paths A to B (the direction of the Z axis on the paper surface). Therefore, if the notch portions along the air flow paths A to B shown in FIG. 10 are also provided on the inverter circuit module 60, the heat dissipation is further improved. In addition, the codes | symbols 70-73 shown by FIG. 8 have shown an example of the notch part along the air flow paths AB shown in FIG.

 In the air conditioner outdoor unit 50, the compressor 53, the motor of the fan 51, and circuit components serve as heat sources, and the main body itself is installed outdoors. Therefore, the inside of the air conditioner outdoor unit 50 tends to be hot. Therefore, since the inverter circuit module 60 itself is also exposed to a high temperature, it is important to appropriately provide not only the overcurrent protection function but also the overtemperature protection function as in the present embodiment.

 As mentioned above, although one embodiment concerning the present invention was described, explanation of the above-mentioned embodiment is for making an understanding of the present invention easy, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents.

 For example, in the above embodiment, the case of the inverter circuit 120 is given as an example of a circuit having both an overcurrent protection function and an overtemperature protection function, but in addition, a signal processing circuit for a motor driver, audio equipment, plasma, etc. Any circuit that needs to have both an overcurrent protection function and an overtemperature protection function, such as a display drive circuit for a display, may be used.

 In addition, as an application example of the inverter circuit module 60, the air conditioner outdoor unit 50 is given as an example, but in various industries such as washing machines, refrigerators, automobiles, robots, FA (Factory Automation), NC (Numerical Control) machine tools, etc. It can be applied to devices that require inverter control.

It is the figure which showed the structure of the inverter apparatus using the inverter circuit which has both an overcurrent protection function and an overtemperature protection function. (A) is a circuit diagram explaining a 1 shunt system, (b) is a circuit diagram explaining a 3 shunt system. It is a wave form chart showing an example of a detection current waveform in each case of 1 shunt system and 3 shunt system. It is the figure which showed the waveform of each gate signal of the switching elements Q1-Q6 in the case of a 3 phase 120 degree | times energization system. It is the figure which showed the detailed structural example of the overcurrent / overtemperature detection circuit. It is the figure which showed the circuit structural example of the open collector output comparator. (A) is sectional drawing of a semiconductor device, (b) is a surface view of a semiconductor device. It is a perspective view of a semiconductor device. (A) is the figure which showed the example of mounting of the 1st board | substrate of a semiconductor device, (b) is the figure which showed the example of mounting of the 2nd board | substrate of a semiconductor device. It is the figure which showed the internal structure of the air-conditioner outdoor unit using an inverter circuit module.

Explanation of symbols

120 Inverter circuit 121 Switching circuit Q1 to Q6 Switching element Ru, Rv, Rw Shunt resistor 123 Overcurrent / overtemperature detection circuit 124 Control circuit 125 Driver circuit 1232 Overcurrent detection circuit 1234 Overtemperature detection circuit 1233a to 1233c Open collector output comparator R2 Temperature detection element R3 Resistance B10 PNP bipolar transistor 1237 Signal line 1A First substrate 2 Second substrate 3 Case material 10 Semiconductor device 31 Integrated circuit 60 Inverter circuit module 50 Air conditioner outdoor unit

Claims (6)

A first resistor that detects a current flowing through the protected circuit as a voltage;
A reference voltage generation circuit for generating a reference voltage;
An overcurrent detection circuit that compares the voltage with the reference voltage, the output becomes high impedance when the voltage does not exceed the reference voltage, and the output becomes a predetermined voltage when the voltage exceeds the reference voltage;
A temperature detection element whose resistance value changes according to temperature, a second resistor connected in series to the temperature detection element, and a control electrode connected to the output of the overcurrent detection circuit, the temperature detection element, and the second resistance When the output of the overcurrent detection circuit is in a high impedance state, it operates according to the voltage at the connection point regardless of the output of the overcurrent detection circuit, and the output of the overcurrent detection circuit An overtemperature detection circuit including a transistor that operates according to the predetermined voltage regardless of the voltage at the connection point when
A control circuit that controls to protect the protected circuit according to the output of the transistor;
A protection circuit comprising: The overcurrent detection circuit includes:
A comparator that compares the voltage with the reference voltage, and that outputs a high impedance when the voltage does not exceed the reference voltage, and that outputs a predetermined voltage when the voltage exceeds the reference voltage. The protection circuit according to claim 1. The first resistor is a shunt resistor.
The protection circuit according to claim 1. A substrate having a conductive pattern on the surface;
An integrated circuit electrically connected to the conductive pattern and disposed on the substrate,
The integrated circuit comprises:
A protected circuit;
A first resistor that detects a current flowing through the protected circuit as a voltage;
A reference voltage generation circuit for generating a reference voltage;
An overcurrent detection circuit that compares the voltage with the reference voltage, the output becomes high impedance when the voltage does not exceed the reference voltage, and the output becomes a predetermined voltage when the voltage exceeds the reference voltage;
A temperature detection element whose resistance value changes according to temperature, a second resistor connected in series to the temperature detection element, and a control electrode connected to the output of the overcurrent detection circuit, the temperature detection element, and the second resistance When the output of the overcurrent detection circuit is in a high impedance state, it operates according to the voltage at the connection point regardless of the output of the overcurrent detection circuit, and the output of the overcurrent detection circuit An overtemperature detection circuit including a transistor that operates according to the predetermined voltage regardless of the voltage at the connection point when
A control circuit that controls to protect the protected circuit according to the output of the transistor;
A semiconductor device comprising: A first substrate having a first conductive pattern on a surface;
A second substrate having a second conductive pattern on the surface;
A first integrated circuit electrically connected to the first conductive pattern and disposed on the first substrate;
A second integrated circuit for controlling the operation of the first integrated circuit, which is electrically connected to the second conductive pattern and disposed on the second substrate;
A case for holding the first substrate and the second substrate in parallel substantially in parallel,
The first integrated circuit includes:
A protected circuit;
A first resistor that detects a current flowing through the protected circuit as a voltage;
A reference voltage generation circuit for generating a reference voltage;
An overcurrent detection circuit that compares the voltage with the reference voltage, the output becomes high impedance when the voltage does not exceed the reference voltage, and the output becomes a predetermined voltage when the voltage exceeds the reference voltage;
A temperature detection element whose resistance value changes according to temperature, a second resistor connected in series to the temperature detection element, and a control electrode connected to the output of the overcurrent detection circuit, the temperature detection element, and the second resistance When the output of the overcurrent detection circuit is in a high impedance state, it operates according to the voltage at the connection point regardless of the output of the overcurrent detection circuit, and the output of the overcurrent detection circuit An overtemperature detection circuit including a transistor that operates according to the predetermined voltage regardless of the voltage at the connection point when
A control circuit that controls to protect the protected circuit according to the output of the transistor;
A semiconductor device comprising: A substrate having a conductive pattern on the surface;
An integrated circuit electrically connected to the conductive pattern and disposed on the substrate;
A case for holding the substrate;
A case in which the case is disposed, and
The integrated circuit comprises:
A protected circuit;
A first resistor that detects a current flowing through the protected circuit as a voltage;
A reference voltage generation circuit for generating a reference voltage;
An overcurrent detection circuit that compares the voltage with the reference voltage, the output becomes high impedance when the voltage does not exceed the reference voltage, and the output becomes a predetermined voltage when the voltage exceeds the reference voltage;
A temperature detection element whose resistance value changes according to temperature, a second resistor connected in series to the temperature detection element, and a control electrode connected to the output of the overcurrent detection circuit, the temperature detection element, and the second resistance When the output of the overcurrent detection circuit is in a high impedance state, it operates according to the voltage at the connection point regardless of the output of the overcurrent detection circuit, and the output of the overcurrent detection circuit An overtemperature detection circuit including a transistor that operates according to the predetermined voltage regardless of the voltage at the connection point when
A control circuit that controls to protect the protected circuit according to the output of the transistor;
Electrical equipment characterized by including.

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