Semiconductor device

Abstract

comprising a semiconductor device: • a detection circuit (110) which is connected between a positive electrode and a negative electrode of a semiconductor switching element (10a), wherein • the detection circuit has a current source (120) and a first resistance element (121) which are connected in series between the positive electrode and the negative electrode via a first node (N1), wherein the first resistance element has a first electrical resistance value (R1), • the current source (120) operates such that an output current (1a) of the current source (120) increases to a saturated constant value (I1) when a voltage of the positive electrode becomes higher relative to a voltage of the negative electrode, • the semiconductor device furthermore comprises a voltage comparator (130) which outputs a comparison result between a DC voltage (Vt) applied to a second node and a voltage of the first node, • the DC voltage and the first electrical resistance value are set such that if an intermediate electrode voltage (Vce) between the positive electrode and the negative electrode becomes higher than a predefined setpoint voltage (Vth), the voltage of the first node is higher than the DC voltage, and • the detection circuit and the voltage comparator are mounted on the same integrated circuit.

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a semiconductor device. Description of the state of the art

[0002] Generally, an inverter or similar device uses a so-called arm configuration, in which two semiconductor switching elements (hereinafter simply referred to as "switching elements") are connected between a high-potential node and a low-potential node via an intermediate potential node. In the arm configuration, the switching element connected to the high-potential side is referred to as the high-side switching element, and the other switching element connected to the low-potential side is referred to as the low-side switching element.

[0003] Japanese Patent No. JP 2019-4535A discloses a semiconductor device comprising a sensing circuit configured to detect the state of the high-side switching element in the arm configuration. As disclosed in Japanese Patent No. JP 2019-4535A, the state of the high-side switching element is monitored by a sensing circuit and a signal transmission circuit, each comprising switching elements located outside the semiconductor chip (IC: integrated circuit). The IC is mounted with a driver circuit for controlling the high-side switching element and the low-side switching element, each of which is formed by an IGBT (insulated-gate bipolar transistor).

[0004] As disclosed in Japanese Patent Publication No. JP 2019-4535A, the sensing circuit outputs a voltage in response to the state of the high-side switching element, and the signal transmission circuit comprises a signal switching element mounted on the semiconductor chip and configured to turn on and off in response to the voltage output of the sensing circuit, and a diode located outside the semiconductor chip and connected in series with the signal switching element. This allows monitoring of the voltage output by the sensing circuit, while the necessary isolation between the high-side and low-side switching elements is ensured by the diode.

[0005] DE 690 05 755 T2 discloses a current measuring circuit with a FET. The current measuring circuit is used as an overcurrent measuring circuit in a power circuit. Summary of the invention

[0006] However, according to the configuration disclosed in Japanese Patent Publication No. JP 2019 4 535 A, since the required isolation between the high-side switching element and the low-side switching element is ensured by a diode connected to the IC from the outside, the state of the switching element is monitored by the elements mounted on the IC and by the element provided outside the IC, thereby increasing the number of components and the size of the circuit.

[0007] On the other hand, it is known that when an overcurrent flows through a switching element, the switching element is placed in an unsaturated state, causing a voltage anomaly. This means that the voltage between the positive and negative electrodes can become abnormally high even when the switching element is in the ON state. Therefore, it is important to detect the voltage anomaly to prevent a continuous overcurrent from flowing through the switching element. In this case, however, it is desirable to detect the voltage anomaly using a simple circuit configuration to replace the complex circuit configuration disclosed in Japanese Patent Publication No. JP 2019 4 535 A.

[0008] It is an object of the present invention to provide a semiconductor device capable of detecting a voltage anomaly between a positive electrode and a negative electrode when a switching element is turned on, while ensuring isolation by means of a simple configuration.

[0009] This problem is solved by the features of independent claim 1. The dependent claims contain advantageous embodiments of the invention.

[0010] According to one aspect of the present invention, a semiconductor device comprises a sensing circuit connected between a positive and a negative electrode of a semiconductor switching element and a voltage comparator. The sensing circuit includes a current source and a first resistive element with a first electrical resistance value. The current source operates such that its output current rises to a saturated constant value when the voltage at the positive electrode increases relative to the voltage at the negative electrode. The current source and the first resistive element are connected in series via a first node between the positive and negative electrodes. The voltage comparator outputs a comparison result between a DC voltage applied to a second node and a voltage at the first node.The DC voltage and the first electrical resistance value are set such that if the interelectrode voltage between the positive and negative electrodes exceeds a predefined threshold voltage, the voltage at the first node will be higher than the DC voltage. The detection circuit and the voltage comparator are mounted on the same integrated circuit.

[0011] The foregoing and further tasks, features, aspects and advantages of the present invention will become clearer with reference to the following detailed description in conjunction with the accompanying figures. Brief description of the characters Fig. 1 is a first circuit diagram illustrating a configuration of a semiconductor device according to a first embodiment; Fig. Figure 2 is a second circuit diagram illustrating the configuration of the semiconductor device according to the first embodiment; Fig. 3 is a concept diagram which illustrates a voltage-current relationship of the in Fig. 1 illustrated detection circuit illustrated; Fig. 4 is a first curve diagram illustrating an example operation of the semiconductor device according to the first embodiment; Fig. Figure 5 is a second curve diagram illustrating an example operation of the semiconductor device according to the first embodiment; Fig. 6 is a first circuit diagram illustrating a configuration of a semiconductor device according to a second embodiment; Fig. Figure 7 is a second circuit diagram illustrating the configuration of the semiconductor device according to the second embodiment; Fig. Figure 8 is a circuit diagram illustrating a configuration of a semiconductor device according to a third embodiment; Fig. 9 is a circuit diagram to illustrate an example configuration of a Fig. 8 illustrated current mirror circuits; Fig. 10 is a circuit diagram illustrating an example configuration of a protection circuit included in a semiconductor device according to a fourth embodiment; Fig. 11 is a first curve diagram illustrating an example operation of the semiconductor device according to the fourth embodiment; and Fig. Figure 12 is a second curve diagram illustrating an example operation of the semiconductor device according to the fourth embodiment. Description of preferred embodiments

[0012] Embodiments of the present invention are described in detail below with reference to the figures. In the following description, identical or corresponding parts in the figures are identified by the same reference numerals, and their description is not repeated. First embodiment

[0013] The Fig. 1 and Fig. Figure 2 each represents a circuit diagram illustrating a configuration of a semiconductor device according to a first embodiment.

[0014] With reference to Fig. 1. A semiconductor device 100A acts as a driver IC for a switching element 10a. The switching element 10a, which is switched on and off by the semiconductor device 100A, is typically formed by an IGBT and is connected between an intermediate potential node 23 and a low potential node 22, to which a low potential ground is applied. In other words, the switching element 10a represents a low-side switching element.

[0015] With reference to Fig. 2 The semiconductor device 100A functions as a driver IC for a switching element 10b. The switching element 10b, which is switched on and off by the semiconductor device 100A, is typically formed by an IGBT and is connected between a high-potential node 21, at which a high potential Vcc is applied, and the intermediate-potential node 23, which is a common feature with Fig. 1 represents. In other words, switching element 10b represents a high-side switching element.

[0016] As in the Fig. 1 and Fig. Figure 2 illustrates the configuration of the semiconductor device 100A ( Fig. 1), which is provided for the low-side switching element 10a and the configuration of the semiconductor device 100A ( Fig. 2), which are provided for the high-side switching element 10b, the configuration of the semiconductor device 100A, which is provided for the low-side switching element, is described in detail.

[0017] Referring again to Fig. 1, the semiconductor device 100A comprises a driver circuit 150 for the switching element 10a, a sensing circuit 110 for sensing a collector-emitter voltage (Vce) of the switching element 10a, and a voltage comparator 130. Vce is equivalent to the voltage between the positive electrode and the negative electrode of the switching element.

[0018] The driver circuit 150 receives a control signal SIN from the switching element 10a and outputs a gate signal SOUT to the gate (control electrode) of the switching element 10a. For example, if the control signal SIN, which is a binary signal, is high (hereinafter referred to as the "H level"), and the gate signal SOUT is set to the H level, the switching element 10a is switched on. The H-level voltage of the gate signal SOUT is set higher than a threshold voltage of the IGBT that forms the switching element 10a, with respect to the negative electrode (emitter) of the switching element 10a.

[0019] If, however, the control signal SIN is at a low level (hereinafter referred to as the "L level"), the switching element 10a is switched off if the gate signal SOUT is set to the L level. For example, the L-level voltage of the gate signal SOUT is set equal to the voltage of the negative electrode (emitter) of the switching element 10a, in other words, the low potential GND.

[0020] The detection circuit 110 comprises a current source 120 and a resistor 121 connected in series. The resistor 121 is preferably a variable resistor. For example, the electrical resistance R1 of the resistor 121 can be adjusted by means of digital trimming.

[0021] The current source 120 and the resistance element 121 are connected in series via a node N1 between the intermediate potential node 23 and the low potential node 22, in other words between the positive electrode (collector) and the negative electrode (emitter) of the switching element 10a.

[0022] The voltage comparator 130 outputs a detection signal Sab in response to a comparison between the voltage V+ of the positive input terminal and the voltage V- of the negative input terminal. The detection signal Sab is set to a high level when V+ > V-, and to a low level when V+ ≤ V-.

[0023] The positive input terminal of the voltage comparator 130 is connected to node N1 of the detection circuit 110. In other words, the voltage V+ is equivalent to the voltage of node N1. A voltage source 135, which provides a DC voltage, is electrically connected between the negative input terminal of the voltage comparator 130 and the low-potential node 22 (the emitter of the switching element 10a). It is preferred that the voltage source 135 is configured to variably adjust the DC voltage Vt. Node N1 corresponds to an embodiment of the "first node," and the negative output terminal of the voltage comparator 130 corresponds to an embodiment of a "second node."The collector-emitter voltage Vce of the switching element corresponds to an embodiment of an “inter-electrode voltage”, and the resistance element 121 of the detection circuit 110 corresponds to an embodiment of a “first resistance element”.

[0024] The current source 120 can, for example, be formed by a diode-connected transistor with a high breakdown voltage, which is provided on an IC that forms the semiconductor device 100A. In the example configuration in Fig. The current source 120 is connected between the intermediate potential node 23 (the collector of the switching element 10a) and node N1. The resistor element 121 is connected between node N1 and the low potential node (the emitter of the switching element 10a). The resistor element 121 is also formed on the IC, which constitutes the semiconductor device 100A.

[0025] The voltage comparator 130 can be constructed from any circuit configuration. For example, if the voltage comparator 130 is formed by using a transistor, a resistor element, and the like, which are provided on the IC forming the semiconductor device 100A, the voltage comparator 130 can be mounted on the IC forming the semiconductor device 100A in the same way as the detection circuit 110.

[0026] In contrast, the voltage source 135 can be located outside the semiconductor device 100A (IC). In this case, the DC voltage Vt is supplied from the outside of the semiconductor device 100A at a terminal (not shown) which is electrically connected to the negative input terminal of the voltage comparator 130. Alternatively, a circuit is used as the voltage source 135 which generates a constant voltage by reducing the high potential Vcc using a transistor or the like on the semiconductor device 100A.

[0027] As described above, it is known that if a switching element (IGBT) in the ON state experiences an overcurrent, the switching element is switched to the unsaturated state, and as a result, the collector-emitter voltage Vce may not be sufficiently reduced, even when the switching element is in the ON state. In the semiconductor device according to the present embodiment, the detection circuit 110 and the voltage comparator 130 are configured to detect the unsaturated state of the switching element 10a (IGBT). Specifically, during the high-level period of the control signal SIN, the voltage comparator 130 sets the detection signal Sab to the high level if the collector-emitter voltage Vce is higher than the set voltage, thereby detecting the unsaturated state.The set voltage Vth can be set lower than the collector-emitter voltage Vce in the unsaturated state, based on the properties of the switching element 10a. Generally, the set voltage Vth is less than 10 V.

[0028] Fig. Figure 3 illustrates a voltage-current relationship of the detection circuit 110. Referring to Fig. 3. In a region where the collector-emitter voltage Vce of the switching element 10a is low, the output current la = 0, while in a region where the collector-emitter voltage Vce is high, the output current la of the current source 120 has a saturated constant value (la = 1). In the Vce region, which contains the determining voltage Vth, the output current la varies according to the collector-emitter voltage Vce, with a rise that is inversely proportional to the electrical resistance value R1 (of the resistive element 121).

[0029] If the voltage of the current source 120 is represented by Va1 and the current of it at time Vce = Vth is represented by la1, then the determining voltage Vth, the voltage Va1 and the current la1 satisfy the following expression (1): Vth=Va1+R1×Ia1

[0030] If the DC voltage Vt is expressed using the current la1 in expression (1) as the following expression (2) when Vce > Vth, the voltage comparator 130 can set the output (sensing signal Sab) to the H level. Vt=R1×Ia1

[0031] Based on expressions (1) and (2), the determining stress Vth can be expressed by the following expression (3): Vth=Va1+Vt

[0032] As can be seen from expression (3), the determining voltage Vth can be adjusted by the electrical resistance R1 of the resistive element 121 and the DC voltage Vt from the voltage source 135. In other words, the determining voltage Vth can be adjusted in accordance with the characteristics of the switching element 10a, which is to be monitored with regard to voltage anomalies.

[0033] The Fig. 4 and Fig. Figure 5 illustrates example operations of the semiconductor device according to the first embodiment. Fig. Figure 4 illustrates a curve diagram during the normal operation of the switching element 10a.

[0034] With reference to Fig. 4. Before time t0, the low-side switching element 10a is in the OFF state because the control signal SIN is set to the L level. Since the high-side switching element 10b is normally in the ON state, at this time Vce = Vcc, and therefore Vce > Vth. As with reference to Fig. As described in section 3, in the detection circuit 110 Ia = I1. In the voltage comparator 130, since Vce > Vth, consequently V+ > V-, and therefore, when the switching element 10a is in the OFF state, the detection signal Sab is at the H level.

[0035] When the control signal SIN changes from a low level to a high level at time t0, the switching element 10a is turned on. Specifically, the gate voltage of the switching element 10a increases when the gate signal SOUT, which is output from the driver circuit 150, changes to a high level. Consequently, the collector-emitter voltage Vce decreases, and a collector-emitter current begins to flow into the switching element 10a.

[0036] If the switching element 10a is in the normal ON state, no unsaturated state occurs in the switching element 10a, and therefore the collector-emitter voltage Vce drops to a voltage close to zero, and a normal collector-emitter current is generated. In other words, the collector-emitter voltage Vce drops lower than the set voltage Vth.

[0037] In response to such a decrease in the collector-emitter voltage Vce, the output current la from the current source 120 in the detection circuit 110 becomes 0 (la = 0), and in the voltage comparator 130, V+ < V-. As a result, the detection signal Sab changes to the L level.

[0038] If the control signal SIN changes from a high level to a low level at time t1, switching element 10a is switched off. This causes Vce, la, V+, and the sensing signal Sab to return to their state before time t0. Consequently, if switching element 10a is in its normal ON state, and the control signal SIN changes to a high level, the sensing signal Sab will change to a low level.

[0039] In contrast, it illustrates Fig. 5. An example operation when an unsaturated state occurs in switching element 10a. With reference to Fig. 5 becomes the switching element 10a, similar to in Fig. 4 is switched on when the control signal SIN changes from the L level to the H level at time t0.

[0040] In Fig. However, in switching element 10a, an unsaturated state occurs due to an excessive collector-emitter current (overcurrent), which causes a voltage anomaly, and as a result, Vce does not rise as in Fig. Figure 4 illustrates this. Due to the voltage anomaly, Vce > Vth, and therefore, in response to the output current la, it is in accordance with a relationship in Fig. 3, V+ > V-. Consequently, the detection signal Sab is, in contrast to Fig. 4 is held at the H level even when the control signal SIN changes to the H level.

[0041] Therefore, according to the first embodiment, the semiconductor device 100A is able to detect the occurrence of an unsaturated state during the ON period of the switching element 10a, based on the detection signal Sab, which is generated by the detection circuit 110 and the voltage comparator 130.

[0042] When the switching element 10a is switched off, the isolation of the sensing circuit 110 between the intermediate potential node 23, where the high potential Vcc is applied, and the low potential node 22 can be ensured by the current source 120 (for example, a diode-connected field-effect transistor with a high breakdown voltage). In other words, it is possible to ensure the isolation of the sensing circuit 110 by using an element (for example, the field-effect transistor with a high breakdown voltage) provided on the IC that forms the semiconductor device 100A comprising the driver circuit 150, instead of using an external element provided outside the IC, such as the one disclosed in Japanese Patent Publication No. 2019-4535.

[0043] Referring again to Fig. 2. The semiconductor device 100A can be applied to the high-side switching element 10b with the same circuit configuration as that described in [reference]. Fig. 1. In this case, the high-potential node 21 corresponds to the circuit configuration in Fig. 2 with the intermediate potential node 23 in Fig. 1, and the intermediate potential node 23 in the circuit configuration in Fig. 2 corresponds to the low-potential node 22 in Fig. 1.

[0044] In Fig. 2. The sensing circuit 110 is connected between the high-potential node 21 and the intermediate-potential node 23, in other words, between the collector and the emitter of the switching element 10b, which makes it possible to sensitize the collector-emitter voltage Vce of the high-side switching element 10b. In other words, the output current la of the current source 120 and the collector-emitter voltage Vce of the switching element 10b satisfy the same relationship as in Fig. 3 illustrated.

[0045] The positive input terminal of the voltage comparator 130 is connected to node N1 of the detection circuit 110 as shown in Fig. 1 connected. In contrast, the voltage source 135 is electrically connected between the intermediate potential nodes 23 and the negative input terminal of the voltage comparator 130. As described above, the DC voltage Vt can be provided by the voltage source 135, which is located outside the semiconductor device 100A.

[0046] The in Fig. The illustrated semiconductor device 100A also operates in response to changes in the control signal SIN for controlling the switching on / off of the switching element 10b in the same way as those described in relation to the Fig. 4 and Fig. 5 is described. In other words, the semiconductor device 100A can be applied to both the low-side switching element 10a and the high-side switching element 10b with the same circuit configuration. Second embodiment

[0047] The second embodiment describes a circuit configuration which is able to easily adjust a determining voltage for detecting the unsaturated state.

[0048] Fig. Figure 6 is a first circuit diagram illustrating the configuration of a semiconductor device according to a second embodiment.

[0049] Referring to Fig. 6. A semiconductor device 100B according to the second embodiment differs from the semiconductor device 100A according to the first embodiment with respect to the configuration of the detection circuit 110. Specifically, the detection circuit 110 in the second embodiment additionally has a resistive element 122, which is connected in series with the current source 120 between the intermediate potential node 23 and the node N1, compared to the configuration in Fig. 1. It is preferable that the electrical resistance value R2 of the resistive element 122 can be variably adjusted by trimming or the like. The configuration of the other parts of the semiconductor device 100B is the same as that of the semiconductor device 100A. The resistive element 122 corresponds to an embodiment of a "second resistive element".

[0050] Due to the addition of the resistive element 122 (which has an electrical resistance value R2) in the detection circuit 110 according to the second embodiment, the expression (1) described above is transformed into the following expression (4): Vth=Va1+(R1+R2)×Ia1

[0051] Also in the second embodiment, if the DC voltage Vt is expressed by using the current la1 in expression (1) in the same way as expression (2), at time Vce = Vth, the determining voltage Vth can be expressed by the following expression (5): Vth=Va1+Vt×(R1+R2) / R1

[0052] In the second embodiment, Sab is set to the high level when Vce > Vth, as expressed by expression (5), while Sab is set to the low level when Vce ≤ Vth. As can be seen from expression (5), the determining voltage Vth in the second embodiment can be adjusted by the DC voltage Vt of the voltage source 135, the electrical resistance value R1 of the resistive element 121, and the electrical resistance value R2 of the resistive element 122.

[0053] The operating principle of the semiconductor device 100B according to the second embodiment is the same as that of the first semiconductor device 100A, with the exception of the setting of the determining voltage Vth. Therefore, in the semiconductor device 100B according to the second embodiment, in addition to the effect of the semiconductor device 100A according to the first embodiment, the determining voltage Vth can be easily adjusted.

[0054] Fig. Figure 7 illustrates a circuit configuration when the semiconductor device 100B according to the second embodiment is applied to the high-side switching element 10b.

[0055] With reference to Fig. 7. The semiconductor device 100B according to the second embodiment can be applied to the high-side switching element 10b with the same circuit configuration as that in Fig. 6 can be applied. In this case, the high-potential node 21 corresponds to the circuit configuration from Fig. 7 with the intermediate potential node 23 in the circuit configuration from Fig. 6, and the intermediate potential node 23 in the circuit configuration from Fig. 7 corresponds to the low-potential node 22 in the circuit configuration from Fig. 6.

[0056] In Fig. 7. The unsaturated state of the switching element 10b can be detected by comparing the collector-emitter voltage Vce of the high-side switching element 10b with the reference voltage Vth. Similar to in Fig. 6, the determining voltage Vth can be adjusted by the DC voltage of the voltage source 135, the electrical resistance value R1 of the resistance element 121 and the electrical resistance value R2 of the resistance element 122.

[0057] In other words, the semiconductor device 100B can also be applied to both the low-side switching element 10a and the high-side switching element 10b with the same circuit configuration. In the second embodiment, it is also possible to change the order of the current source 120 and the resistor element 122, which in the circuit configuration of the Fig. 6 and Fig. 7 are connected in series. Third embodiment

[0058] A preferred example configuration of the power source 120 of the detection circuit 110 according to a third embodiment is described.

[0059] Fig. Figure 8 is a circuit diagram illustrating a configuration of a semiconductor device according to the third embodiment.

[0060] With reference to Fig. Figure 8 shows a semiconductor device 100C according to the third embodiment, an example configuration of a power source 120 which is included in the detection circuit 110 of the semiconductor device 100B according to the second embodiment.

[0061] Specifically, in the third embodiment, the current source 120 of the detection circuit 110 comprises a current mirror circuit 125 and a current mirror circuit 126. The remaining configuration in Fig. 8 is the same as that of the second embodiment ( Fig. 6), and its detailed description is not repeated. In other words, the detection signal Sab in the semiconductor device 100C is generated in the same way as in the semiconductor device 100B according to the second embodiment, and consequently the occurrence of Vce > Vth, in other words, the occurrence of an unsaturated state of the switching element 10a, can be detected in the same way as in the second embodiment.

[0062] In the third embodiment, the current source 120 is furthermore configured to include the current mirror circuits, thus stabilizing the output current la and improving the accuracy of detecting whether Vce > Vth or not. As described below, the components (the transistors and resistors) of the current mirror circuits 125 and 126 can also be arranged on the IC that forms the semiconductor device 100C, similar to the voltage comparator 130 and the driver circuit 150.

[0063] Fig. Figure 9 illustrates a preferred example configuration of the current mirror circuits 125 and 126, which are shown in Fig. 8 are illustrated.

[0064] With reference to Fig. 9 the current source 120 comprises the transistors T1 to T3, which form the current mirror circuit 125, the transistors T4 to T6, which form the current mirror circuit 126, and a resistor element 123.

[0065] In the current mirror circuit 125, transistor T1 is connected between the intermediate potential node 23 (the collector of the switching element 10a) and a node N2, transistor T2 is connected between the intermediate potential node 23 and a node N3, and transistor T3 is connected between node N2 and the resistive element 121. The gate of transistor T1 and the gate of transistor T2 are connected to node N2, and the gate of transistor T3 is connected to node N3.

[0066] In the current mirror circuit 126, transistor T4 is connected between node N3 and node N4, transistor T5 is connected between node N4 and the low-potential node 22, and transistor T5 is connected between node N5 and the low-potential node 22 (the emitter of switching element 10a). The gate of transistor T5 and the gate of transistor T6 are connected to node N4. The gate of transistor T4 is connected to node N5, and node N5 is connected via resistor element 123 (which has a resistance value of R3) to the high-potential node 21.

[0067] According to an example configuration in Fig. Since each of the current mirror circuits 125 and 126 is designed as a Wilson current mirror circuit, it is possible to improve the accuracy in detecting the output current la of the current source 120. Consequently, it is possible to improve the accuracy in setting the determining voltage Vth, which in turn improves the accuracy of detecting whether Vce > Vth or not; in other words, the accuracy of detecting an unsaturated state of the switching element.

[0068] In the example configuration from Fig. 9, since each of the transistors T3 and T4 is formed by a transistor with a high breakdown voltage, it is possible to ensure the isolation of the detection circuit 110.

[0069] It should be noted that the in Fig. Figure 7 illustrates that the power source 120 in the semiconductor device 100B can be constructed in the same way as those described in relation to the Fig. 8 and Fig. 9 is described. In other words, the semiconductor device 100C according to the third embodiment can also be applied to both the low-side switching element 10a and the high-side switching element 10b with the same circuit configuration.

[0070] The semiconductor device according to the third embodiment can be realized by placing the current source 120 in the semiconductor device 100A of the first embodiment ( Fig. 1 and Fig. 2) is trained in such a way that they can perform tasks related to the Fig. 8 and Fig. The 9 described current mirror circuits comprise. Fourth embodiment

[0071] In the fourth embodiment, a description is given regarding a protective circuit which is initialized in response to the detection of an unsaturated state of the switching element, as described in the first to third embodiments.

[0072] Fig. Figure 10 is a circuit diagram illustrating an example configuration of a protection circuit 180, which is included in the semiconductor device according to the fourth embodiment. The semiconductor device according to the fourth embodiment differs from the semiconductor devices 100A to 100C according to the first to third embodiments in that the control signal SIN is fed into the driver circuit 150 via the protection circuit 180.

[0073] With reference to Fig. 10, the protection circuit 180 has a delay circuit 181, a NAND gate 182 and an AND gate 183.

[0074] The delay circuit 181 outputs a delay signal S1 by adding a delay time Td to the control signal SIN. The NAND gate 182 outputs a signal S2 corresponding to the result of a NAND operation performed on the sensing signal Sab output by the voltage comparator 130 and the delay signal S1. The delay circuit 181 can, for example, be formed from a plurality (an even number) of inverters (NOT gates) connected in series.

[0075] The AND gate 183 generates a control signal S3, which is output to the driver circuit 150 in accordance with the result of an AND operation performed on the control signal SIN (which bypasses the delay circuit 181) and the signal S2. The driver circuit 150 generates a gate signal SOUT in accordance with the control signal S3.

[0076] Next, an example operation of the semiconductor device according to the fourth embodiment will be described with reference to the Fig. 11 and Fig. 12 described. Similar to Fig. 4, illustrated Fig. 11. An example curve diagram during normal operation.

[0077] With reference to Fig. 11, Vce, la, V+ and the detection signal Sab change as in Fig. 4, if the control signal SIN, as in Fig. 4, at time t0, changes from the low level to the high level. As described above, the detection signal Sab changes from the high level to the low level in normal operation in response to the decrease of Vce.

[0078] The delay signal S1 changes from a low level to a high level at time tx, after the delay time Td, which is defined by the delay circuit 181, has elapsed from time t0. The delay time Td is determined in advance such that it is longer than the required circuit processing time from the start of power-up (time t0) until the detection signal Sab changes to a low level during normal operation.

[0079] From time t0 to time tx, the delay signal S1 is set to a low level, which keeps the signal S2 output by NAND gate 182 at a high level. Furthermore, the detection signal Sab is set to a low level from time tx to time t1, which also keeps signal S2 at a high level.

[0080] Therefore, the signal S2 fed into the AND gate 183 during normal operation is always held at a high level. Consequently, the control signal S3 fed into the driver circuit 150 has the same waveform as the control signal SIN. As a result, the switching elements 10a and 10b are switched on and off in response to the control signal SIN by the gate signal SOUT from the driver circuit 150 of the semiconductor device according to the fourth embodiment.

[0081] On the other hand, it illustrates Fig. 12 an example operation when an unsaturated state in switching element 10a as in Fig. 5 occurs.

[0082] With reference to Fig. 12. The control signal SIN changes similarly to the Fig. 5 and Fig. 11 from the L level to the H level at time t0. The curve of the delay signal S1 is the same as that in Fig. 11 (during normal operation). Therefore, the signal S2 is held at the low level until time tx, at which time the delay signal S1 changes to the high level.

[0083] Therefore, the control signal S3 fed into the driver circuit 150 is identical to the control signal SIN at least until time tx, whereby the switching elements 10a and 10b function as in Fig. 11 will be switched on.

[0084] The behavior of Vce, la, V+ and the detection signal Sab at the time an unsaturated state occurs in the switching elements 10a and 10b are the same as those in Fig. 5. In other words, the detection signal Sab is held at the H level for the period in which the control signal SIN is held at the H level.

[0085] As a result, the signal S2 output by NAND gate 182 changes to a low level after time tx. In response, the control signal S3 output by AND gate 183 is set to a low level, forcing switching elements 10a and 10b to switch off (turn off) due to the detection of the unsaturated state. Consequently, switching elements 10a and 10b are protected against overcurrent.

[0086] As described above, according to the semiconductor device of the fourth embodiment, it is possible to implement a protective function in addition to the effects of the respective semiconductor device according to the first to third embodiments, so that the switching element is automatically switched off in response to the detection of an unsaturated state.

[0087] The protection circuit 180 can be a logic circuit such as a CMOS (complementary metal oxide semiconductor) logic circuit, which is formed from transistors on the IC, each of which forms the semiconductor devices 100A to 100C. Consequently, the protection circuit 180 can be mounted on the same integrated circuit as the detection circuit 110, the voltage comparator 130, and the driver circuit 150. Alternatively, the protection circuit 180 can be provided outside the semiconductor device (IC), and a signal corresponding to the control signal S3 can be fed into the driver circuit 150 from outside the semiconductor device.

[0088] In the embodiments of the present disclosure, an IGBT is described as the switching elements 10a and 10b by way of example, but by applying the semiconductor device according to the first to fourth embodiments to the switching element, different from the IGBT used in the high-side arm and the low-side arm, it is possible to detect a voltage anomaly between the positive electrode and the negative electrode when the switching elements 10a and 10b are switched on while the insulation is ensured.

[0089] Although the embodiments of the present invention have been described, it should be understood that the embodiments disclosed herein are in every respect illustrative and not limiting. It is intended that the scope of protection of the present invention is defined by the claims and includes all modifications within the meaning and scope that are equivalent to the claims.

Claims

[1] comprising a semiconductor device: • a detection circuit (110) which is connected between a positive electrode and a negative electrode of a semiconductor switching element (10a), wherein • the detection circuit has a current source (120) and a first resistance element (121) which are connected in series between the positive electrode and the negative electrode via a first node (N1), wherein the first resistance element has a first electrical resistance value (R1), • the current source (120) operates such that an output current (1a) of the current source (120) increases to a saturated constant value (I1) when a voltage of the positive electrode becomes higher relative to a voltage of the negative electrode, • the semiconductor device furthermore comprises a voltage comparator (130) which outputs a comparison result between a DC voltage (Vt) applied to a second node and a voltage of the first node, • the DC voltage and the first electrical resistance value are set such that if an intermediate electrode voltage (Vce) between the positive electrode and the negative electrode becomes higher than a predefined setpoint voltage (Vth), the voltage of the first node is higher than the DC voltage, and • the detection circuit and the voltage comparator are mounted on the same integrated circuit. [2] Semiconductor device according to claim 1, wherein • the detection circuit (110) further comprises a second resistive element (122) which is connected in series with the current source (120) between the positive electrode and the first node (N1), • the second resistive element has a second electrical resistance value (R2), • the first electrical resistance values ​​(R1), the second electrical resistance value (R2) and the DC voltage (Vt) are set in such a way that if the intermediate electrode voltage (Vce) becomes higher than the target voltage (Vth), the voltage of the first node is higher than the DC voltage. [3] Semiconductor device according to claim 1 or 2, wherein the power source (120) comprises a diode-connected field-effect transistor. [4] Semiconductor device according to claim 1 or 2, wherein the current source (120) comprises a plurality of field-effect transistors (T1 to T6) which form a current mirror circuit (125, 126). [5] Semiconductor device according to one of claims 1 to 4 further comprising a driver circuit (150) which controls a control electrode of the semiconductor switching element (10a), • wherein the driver circuit is mounted on the same integrated circuit as the detection circuit (110) and the voltage comparator (130). [6] Semiconductor device according to claim 5 further comprising a protection circuit (180) which receives a first control signal (SIN) for controlling the switching on and off of the semiconductor switching element (10a) and an output signal (Sab) from the voltage comparator (130) and outputs a second control signal (S3) to the driver circuit, • wherein the second control signal is generated to instruct the driver circuit (150) to turn off the semiconductor switching element when the intermediate electrode voltage (Vce) does not become less than the set voltage (Vth), even if the first control signal changes from a first level (L) indicating the turning off of the semiconductor switching element to a second level (H) indicating the turning on of the semiconductor switching element. [7] Semiconductor device according to claim 6, wherein the protection circuit (180) is mounted on the same integrated circuit as the driver circuit (150).

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