Method and electronic circuit for testing the functionality of a transistor component

Abstract

Disclosed herein is a method and an electronic circuit for checking the functionality of a transistor assembly (1). The method includes: a first change in the charge state of an internal capacitance (11) present between the drive control terminals (G, S) of the transistor assembly; determining the capacitance value (C GS ) of the internal capacitance (11) based on the first change in the charge state; a second change in the charge state of the internal capacitance (11); and evaluating the resistance value (R GS ) of an internal resistance (12) present between the drive control terminals (G, S) based on the determined capacitance value (C GS ).

Description

Technical Field

[0001] The present description relates to a method and a circuit for checking the functionality (integrity) of a transistor component, in particular a transistor component with an insulated gate. Background Art

[0002] Transistor components with an insulated gate, such as MOSFETs (metal oxide semiconductor field effect transistors) or IGBTs (insulated gate bipolar transistors), are widely used as electronic switches in many areas, for example in the automotive sector, in the industrial sector, in the field of household appliances or in the field of entertainment electronics. Depending on the field of application, the voltage resistance of such transistor components can vary between tens of volts (V) and several kilovolts (kV).

[0003] At the end of the manufacturing process, the functionality of the transistor components is checked. However, in certain applications, especially safety-critical applications such as in motor vehicles, it is necessary to check the functionality (integrity) of the transistor components during operation in order to be able to take appropriate measures in the event of a malfunction of the transistor component. Summary of the invention

[0004] There is a need for a method for checking the functionality of a transistor component during operation which method does not affect the operation of the transistor component as much as possible, and for a circuit for carrying out such a method.

[0005] One example relates to a method for checking the functionality of a transistor component. The method comprises: a first change in a charge state of an internal capacitance present between control terminals of the transistor component; determining a capacitance value of the internal capacitance based on the first change in the charge state; a second change in the charge state of the internal capacitance; and based on the determined capacitance value and the second change in the charge state, evaluating a resistance value of an internal resistance present between the control terminals.

[0006] Another example relates to an electronic circuit designed to: be connected to drive control terminals of a transistor component; perform a first change in a charge state of a capacitor present between the drive control terminals of the transistor component; determine a capacitance value of the capacitor based on the first change in the charge state; perform a second change in the charge state of the capacitor present between the drive control terminals of the transistor component; and evaluate and determine a resistance value of a resistor present between the drive control terminals based on the determined capacitance value and the second change in the charge state. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Examples are described below with reference to the accompanying drawings. The accompanying drawings are intended to illustrate certain principles and therefore only show aspects necessary for understanding these principles. The accompanying drawings are not drawn to scale.

[0008] Figure 1A circuit representing an example of application for a transistor assembly is shown;

[0009] Figure 2 Schematically shows signal curves of a control voltage and a load path voltage of a transistor component in an on state and an off state;

[0010] Figure 3A and Figure 3B An example of a driver circuit for driving a transistor component is shown;

[0011] Figure 4 A flow chart showing an example of a method for checking functionality of a transistor component, the method comprising a first change and a second change of a charge state of an internal capacitance of the transistor component;

[0012] Figure 5 and Figure 6 schematically shows an example of a first change and a second change of a charge state of an internal capacitance based on a signal curve of a drive voltage of a transistor component;

[0013] Figure 7 A circuit arrangement with a transistor component and a circuit for checking the functionality of the transistor component are shown;

[0014] Figure 8 A signal curve is shown which describes a first example of a method for checking the functionality of a transistor component;

[0015] Fig. 9A and 9B shows a method suitable for executing Figure 8 An example of a circuit arrangement of the method;

[0016] Fig.10 An example of a voltage supply circuit designed to provide two different supply voltages is shown;

[0017] Fig.11 is an example of a circuit having a transistor component and an external discharge resistor;

[0018] Fig.12 A signal curve is shown which describes a method for checking an external discharge resistor;

[0019] Fig.13 shows a variation of the circuit according to FIG. 9 ;

[0020] Fig.14 shows a time curve which describes the application Fig.13 The circuit shown is a method for checking the functionality of a transistor component;

[0021] Fig.15 Shown according to Fig.13Variations of the circuit;

[0022] Fig.16 shows a time curve which describes the application Fig.15 The circuit shown is a method for checking the functionality of a transistor component;

[0023] Fig.17 Shown according to Fig.15 Variations of the circuit;

[0024] Fig.18 shows a time curve which describes the application Fig.17 The circuit shown is a method for checking the functionality of a transistor component;

[0025] Fig.19 Shown according to Fig.17 Variations of the circuit; and

[0026] Fig. 20 A signal curve is shown which describes a further method for testing the functionality of a transistor component.

[0027] In the drawings, the same reference numerals denote the same features. Of course, unless explicitly stated otherwise, the features of the various exemplary embodiments described herein may be combined with one another. DETAILED DESCRIPTION

[0028] Figure 1 An example of a circuit is shown having a transistor assembly 1 , a driver circuit 2 for driving the transistor assembly 1 , and a load Z which is connected in series with a load path DS of the transistor assembly. Figure 1 The load Z in the figure indicates that the current I is obtained through the transistor component 1. DS A series circuit of the load path of the transistor assembly 1 and the load Z is connected, for example, between terminals for a positive power supply potential and a negative power supply potential or ground GND, to which a power supply voltage V+ (hereinafter also referred to as a load power supply voltage) is applied.

[0029] exist Figure 1 In the example shown, the transistor component 1 has the function of a high-side switch, i.e. the switch is an electronic switch whose load path is connected between the load Z and the node for the positive power supply potential. However, this is only an example. The load path of the transistor component 1 and the load Z can also be interconnected in any other configuration. Therefore, the transistor component 1 can also have the function of a low-side switch, i.e. the switch is a switch connected between the load and the negative power supply potential or the ground GND.

[0030] The transistor component 1 is a voltage-controlled transistor component which operates according to a control voltage V applied between the control terminals. GS On or off. Figure 1The transistor component in FIG. 1 is a MOSFET having a gate terminal G, a drain terminal D and a source terminal S. The load path of the MOSFET extends between the drain terminal D and the source terminal S. The control terminal of the MOSFET is Figure 1 In the example shown, the gate terminal G and the source terminal S; therefore, the driving voltage V GS is the voltage between the gate terminal G and the source terminal S. However, it is only an example that the source terminal S is one of the load path terminals of the transistor component 1 and at the same time one of the control terminals. The control terminal, between which the control voltage is applied, can also be separated from the load path terminal. Therefore, according to another example (not shown), the second control terminal is separated from the second load path terminal of the transistor component.

[0031] In any case, the transistor assembly 1 depends on the drive voltage V applied between the drive terminals G, S. GS And turn on and off, where, for example, when the drive voltage V GS When the driving voltage V GS When the voltage Vth is lower than the threshold voltage, the transistor element 1 is turned off. Figure 2 Shown in.

[0032] Figure 2 The driving voltage V GS and the load path voltage V DS The load path voltage is the voltage between the first load path terminal D and the second load path terminal S as a function of time. Figure 2 In the example shown, the drive voltage V GS The off level V has a voltage lower than the threshold voltage Vth. OFF or a turn-on level V higher than the threshold voltage Vth ON When the driving voltage V GS With shutdown level V OFF When the transistor component 1 is in the off state, the load path voltage V DS Basically equal to the load power supply voltage V+. When the drive voltage V GS With on level V ON When , transistor component 1 is in the on state. The load path voltage V DS In this case, the load current I flowing through the transistor arrangement 1 is significantly smaller than in the off state and is essentially DS Multiplying by the on-resistance of the transistor component yields , wherein the on-resistance is the resistance of the transistor component in the on state.

[0033] exist Figure 2 In the example shown, the drive voltage VGS At a first time t01, the threshold voltage Vth is exceeded, wherein the transistor component switches to the on state from this time point and the load path voltage V DS Descend. Figure 2 In the example shown, starting from the second time point t02, the driving voltage V GS starts to decrease, wherein at the third time point t03, the driving voltage V GS is lower than the threshold voltage Vth, so that the transistor component is turned off from time point t03.

[0034] exist Figure 1 In the example shown, the transistor component 1 is driven by a driver circuit 2, which obtains a driving signal S DRV and the first power supply voltage V SUP1 Considering the drive signal S DRV , the driver circuit 2 is designed to operate from a first power supply voltage V SUP1 Generate drive voltage V GS In particular, the driver circuit 2 is configured to: DRV When the signal level indicates that the transistor component 1 should be turned on, the driving voltage V GS The on-level V ON ; and when the drive signal S DRV When the signal level indicates that the transistor component 1 should be turned off, the driving voltage V GS The shutdown level V OFF Optionally, a series resistor 21 is connected between the output of the driver circuit 2 and a control input of the transistor arrangement 1 formed by the first and second control terminals G, S.

[0035] Figure 3A An example of a driver circuit 2 is shown. The driver circuit 2 is designed to be based on a driving signal S DRV and the first power supply voltage V SUP1 To generate the driving voltage V GS The driver circuit 2 comprises a half-bridge with a high-side switch (HS switch) 21 and a low-side switch (LS switch) 22, wherein the load paths of these switches 21, 22 are connected between the power supply terminal and the second drive control terminal (source terminal S) of the transistor component 1, so that a first power supply voltage V is applied to the half-bridge. SUP1 The output of the half bridge formed by the circuit node shared by the HS switch 21 and the LS switch 22 is connected to the first drive control terminal (gate terminal G) of the transistor component 1. In the driver circuit 2, the drive control voltage V GS is the voltage on the LS switch 22. The two switches 21 and 22 of the half bridge are driven according to the driving signal S DRVare driven and complement each other so that only one of the two switches 21 and 22 is turned on at the same time. GS The on-level V ON , for example, the HS switch 21 is driven to be turned on and the LS switch 22 is turned off. In a corresponding manner, the HS switch 21 is driven to be turned off and the LS switch 22 is driven to be turned on to generate the off level V OFF , among which Figure 3A In the example shown, the shutdown level V OFF Corresponds to zero voltage. Depends on the drive signal S DRV The two switches 21 , 22 can be actuated by an optional control circuit 23 .

[0036] The HS switch 21 and the LS switch 22 can be designed as any electronic switch, and in particular, the HS switch can be designed as a bidirectionally cutoff electronic switch.

[0037] Reference Figure 3B For example, if the HS switch 21 and the LS switch 22 are implemented as complementary transistors (they receive the drive control signals S DRV ), you can omit it as Figure 3A The control circuit 23 is shown. The HS switch 21 is, for example, a p-conducting MOSFET (p-MOSFET), and the LS switch 22 is an n-conducting MOSFET (n-MOSFET). The two MOSFETs 21, 22 are, for example, interconnected so that their drain terminals are connected to each other and to the gate terminal G of the transistor assembly.

[0038] according to Figure 3B The p-MOSFET 21 and n-MOSFET 22 can be implemented as unidirectional cut-off components that can cut off voltages having only one specific polarity in a driven state, and when the voltage has an opposite polarity, the internal body diode is turned on regardless of the switching state of the MOSFET (i.e., regardless of whether the MOSFET is driven on or off). Figure 3B In the example shown, the n-MOSFET 22 is interconnected so that when the driving voltage V GS When the driving voltage V GS Less than or equal to the first power supply voltage V SUP1 When , the p-MOSFET is turned off in the controlled off state.

[0039] Optionally, a diode 24 may be connected in series with the p-MOSFET 21, the diode being polarized so that it is connected in anti-series with an internal body diode (not shown) of the p-MOSFET 21. GScan rise to the first power supply voltage V SUP1 This may be necessary to check the functionality of the transistor component 1, as will be explained in detail below.

[0040] refer to Figure 1 The transistor component has an internal capacitance 11 between the drive terminals G, S, which is usually referred to as the gate-source capacitance in MOSFET and is also referred to as the drive capacitance of the transistor component 1 below. In addition, the transistor component 1 has an internal resistance 12 parallel to the drive capacitance 11, which is usually referred to as the gate-source resistance in MOSFET and represents the leakage current behavior of the drive capacitance 11. Ideally, the resistance value R of the internal resistance 12 is GS The capacitance value C of the drive control capacitor 11 is very high (for example, in the range of several gigaohms (GΩ) or higher). GS This depends in particular on the respective design of the transistor component 1 .

[0041] In various applications, in particular safety-critical applications, such as in automobiles, it is desirable to check the functionality of the transistor assembly 1 during operation. The functionality of the transistor assembly 1 depends essentially on the resistance value R of the internal resistor 12. GS and the capacitance value C of the drive control capacitor 11 GS , where for example when the resistance value R GS When the capacitance C GS The transistor component 1 is assumed to have a specified functionality when it is within a predetermined capacitance range, i.e., when the following formula is satisfied:

[0042] R GS >R GS_MIN (1a),

[0043] C GS_MIN <C GS <C GS_MAX (1b),

[0044] Among them, R GS_MIN The resistance value R of the internal resistor 12 is shown in GS The minimum value of C GS_MIN and C GS_MAX Define the capacitance value C of the drive control capacitor 11 GS It is desirable that during operation of the transistor assembly 1, the resistance value R is checked as follows GS and capacitance C GS : whether these values ​​are within the permitted range, i.e. whether these values ​​satisfy the conditions defined, for example, under (1a) and (1b), so that the functionality of the transistor component 1 can be inferred based on this. According to one example, it is assumed that when the resistance value R GS Less than the minimum value R GS_MINOr when the capacitance C GS Outside the range defined according to (1b), the transistor component 1 is no longer functional.

[0045] An example of this method for checking the functionality of a transistor assembly is described below. For explanation only, the transistor assembly 1 in these examples is a MOSFET whose drive input is formed by a gate terminal G and a source terminal S. However, this is only an example. The method is used to check the functionality of the transistor assembly 1 based on checking the internal capacitance 11 and the internal resistance 12, and the method is not limited to MOSFET, but can be applied to any other voltage-driven transistor assembly with an insulated gate, such as IGBT, HEMT (high electron mobility transistor), etc. The MOSFET shown in the example explained below is a normally closed n-conducting MOSFET. This is also only an example. The method is also applicable to p-conducting MOSFETs and normally closed and normally open MOSFETs, wherein the various types of MOSFETs (n-conducting or p-conducting, normally closed or normally open) are distinguished only by their corresponding threshold voltages.

[0046] exist Figure 4 An example of a method for checking the functionality of a transistor component 1 is shown in FIG. 1 with the aid of a flow chart. The method comprises: a first change in the charge state of an internal capacitance 11 present between the control terminals G, S of the transistor component 1 (see Figure 4 Based on the first change in the state of charge, the capacitance value C of the internal capacitor 11 is determined. GS (See Figure 4 102 in ); a second change in the charging state of the internal capacitor 11 (see Figure 4 103); and based on the determined capacitance value C GS and for the second change in the state of charge, evaluating the resistance value R of the internal resistor 12 between the control terminals G, S GS (See Figure 4 104 in the figure). The first and second changes in the charging state of the internal capacitor 11 are respectively related to the driving voltage V GS related to changes in .

[0047] According to an example, a first change of the charging state is performed so that during the first change of the charging state, the voltage V GS The difference between the internal capacitance 11 and the threshold voltage Vth increases. This prevents the first change in the charge state of the internal capacitance 11 from influencing the switching state of the transistor component 1 in an undesirable manner. If, for example, the transistor component 1 is implemented as an n-conducting MOSFET and the functionality of the transistor component 1 is to be tested in the switched-on state, the charge state of the internal capacitance 11 is changed during the first change, for example, so that the control voltage V GSRelative to the on level V ON Continue to rise. Figure 5 During the second change period, the drive voltage decreases again in the direction of the on-level.

[0048] If the transistor component 1 is implemented, for example, as an n-conducting MOSFET and the function of the transistor component 1 is to be tested in the switched-off state, during a first change, for example, the charge state of the internal capacitor 11 is changed so that the control voltage V GS Relative to the shutdown level V OFF Continue to decline. Figure 6 During the second change period, the drive voltage will rise again in the direction of the off level.

[0049] In accordance with Figure 5 In the example and according to Figure 6 In the example, during the inspection phase, the drive voltage V GS The difference to the threshold voltage Vth is increased in order to prevent the functionality of the test transistor component 1 from influencing its switching state. The "test phase" comprises at least the first and second changes to the charge state of the internal capacitance 11 described.

[0050] refer to Figure 7 The internal capacitance 11 and the internal resistance 12 are checked, for example, by means of a check circuit 3, which is connected to the control inputs G, S of the transistor assembly 1. An example for realizing the check circuit 3 and its operating principle is described in more detail below.

[0051] In the examples described below, it is respectively assumed that the functionality of the transistor component 1 is checked when the transistor component 1 is in the switched-on state. GS With on level V ON , and during the first change of the charging state of the internal capacitor 11, the driving voltage V GS However, this is only an example. The example described below can also be modified in a simple manner so that the functionality of the transistor component 1 is checked in the off state and during the first change in the charge state of the internal capacitance 11, the control voltage V GS Continue to descend.

[0052] Figure 8 An example of a method for checking the internal capacitor 11 and the internal resistor 12 is shown. In the method, a first change in the charging state of the internal capacitor 11 includes: charging the internal capacitor 11 with a constant charging current I3, thereby driving the voltage V GS From the on level V ON To determine the capacitance CGS , in this method, the drive voltage V is measured when the charging current I3 flows. GS More precisely, in this method, the drive voltage V is determined GS How long does it take for the first voltage level V1 to rise to the higher second voltage level V2? The first voltage level V1 is higher than the on-level and Figure 8 In the example shown, the first voltage level is reached at the first time point t11. The first time point t11 ​​is located after the start time point t01 of the inspection process, wherein from the start time point t01, the capacitor 11 is connected from the on level V ON Start being charged.

[0053] like Figure 8 As shown, the drive voltage V GS The second voltage level V2 is reached at the second time point t12. According to the time difference Δt1=t12-t11 between the first and second time points t11, t12 and the voltage difference ΔV=V2-V1 between the second voltage level V2 and the first voltage level V1, the capacitance value C can be determined. GS as follows:

[0054]

[0055] exist Figure 8 In the example shown, the second change to the charging state includes: discharging the internal capacitor 11 only through the internal resistor 12, thereby starting from the second time point t12, the driving voltage V GS Edge-on level V ON The direction of decrease is exponential. Figure 8 In the example shown, starting from the second time point t12, the driving voltage V GS It follows from the following:

[0056]

[0057] Where τ1 represents the time constant of the RC device formed by the internal capacitor 11 and the internal resistor 12, which is given by the following equation:

[0058] τ1=C GS ·R GS (4).

[0059] Therefore, taking into account the previously determined capacitance value C GS In the case of GS For example, by determining until the driving voltage V GSThe time constant τ1 is determined by the time period required for a predetermined voltage level (such as the second voltage level V2) to drop to another predetermined voltage level (such as the first voltage level V1). Let t13 be the third time point, at which the driving voltage V GS Then it drops to the first voltage level V1, and Δt2=t13-t12 is the driving voltage V GS The time period from the second voltage level V2 to the first voltage level V1. Considering formula (3), for the driving voltage V at the third time point t13 GS (t13) Applicable:

[0060]

[0061] Based on formula (5a) the following applies for the time constant τ1:

[0062]

[0063] Wherein, Δt2 represents the time difference between the third time point t13 and the second time point t12. Considering the time constant τ1 thus obtained and considering the previously determined capacitance value C GS , the resistance value R of the internal resistor 12 can be determined by considering equation (4) GS , or at least evaluate it as follows: the resistance value R GS Is it higher than the expected minimum resistance R GS_MIN .

[0064] For illustration purposes only, assume that Figure 8 In the example shown, the second change to the charging state includes: GS Discharge from the second voltage level V2 to the first voltage level V1, and determine the time period Δt2 required for this purpose. Of course, it is also possible to measure a required time period during the discharge process of the drive control capacitor 12 to discharge the drive control capacitor 11 from any voltage level except the second voltage level V2 to any other voltage level except the first voltage level V1.

[0065] Fig. 9A An example of a check circuit 3 is shown, which is designed to perform Figure 8 The inspection circuit 3 comprises: a controller 31, which is designed to control the inspection method; a current source 32, which is designed to provide a constant charging current I3; and a switch 33, which is also referred to as a charging switch hereinafter. A series circuit of the current source 32 and the switch 33 is connected between the other terminal for the power supply potential and the first drive terminal (gate terminal) G. A voltage higher than the first power supply voltage V is applied between the other terminal for the power supply potential and the second drive terminal (source terminal). SUP1 The second power supply voltage VSUP2 , so that when the switch 33 is closed, the second power supply voltage V is approximately applied between the drive control terminals G and S SUP2 The switch 33 is opened or closed according to a control signal S33 generated by the controller 31 .

[0066] exist Fig. 9A In the example shown and in the examples described below, the switch 33 can be implemented as any electronic switch, in particular as a bidirectionally blocked electronic switch. Fig. 9B In the example shown in FIG. 3 , the switch 33 includes a MOSFET 331 such as a p-MOSFET, and a diode 332 connected in series with the MOSFET 331, which is connected in anti-series with a body diode (not shown) of the MOSFET 331. The MOSFET 331 and the diode 332 are interconnected so that when the MOSFET 331 is driven to turn on, the driving capacitor 11 can be charged, but the discharge of the driving capacitor 11 via the MOSFET 331 is prevented.

[0067] Reference Fig. 9A The inspection circuit 3 further comprises a comparator 34, which obtains the driving voltage V at the first input. GS , and optionally obtain the first voltage level V1 or the second voltage level V2 at the second input. Which of the two voltage levels V1, V2 is fed to the comparator 34 is also controlled by the controller 31, which is shown in Figure 9, that is, the conversion switch 35 controlled by the controller 31 is connected upstream of the second input of the comparator 34. The controller 31 switches the conversion switch according to the control signal S35, thereby controlling the first voltage level V1 or the second voltage level V2 to be delivered to the second input of the comparator 34 through the control of the controller 31.

[0068] The controller 31 is designed to: at the beginning of the inspection process, close the first switch 33 to inspect the internal capacitor 11 and the internal resistor 12, thereby charging the internal capacitor 11 according to the constant charging current I3 provided by the current source 32; and drive the conversion switch 35 so that the comparator 34 first obtains the first voltage level V1 at its second input. GS When the first voltage level V1 is reached, the comparator output signal S34 (which is transmitted to the controller 31) changes. Then, the controller 31 switches the conversion switch 35 so that the second input of the comparator 34 obtains the second voltage level V2. In addition, when the comparator output signal S34 indicates that the driving voltage V GS When the voltage level V2 rises to the second voltage level, the controller 31 opens the switch 33 to end the charging process. GSOr obtain a signal representing the driving voltage, and the controller is designed to determine the capacitance value C of the internal capacitor 11 in the above manner GS The comparator output signal S34 is used in the controller 31 to indicate the first time point t11 ​​and the second time point t12. The first time point t11 ​​is when the driving voltage V GS When the first voltage level V1 is reached, the second time point t12 is when the driving voltage V GS It exists when the second voltage level V2 is reached.

[0069] When the driving voltage V GS When the second voltage level V2 is reached, the controller 31 cuts off the switch 33, so that the internal capacitor 11 is no longer charged and is discharged via the internal resistor 12. In addition, the controller 31 switches the conversion switch S35, so that the first voltage level V1 is applied to the second input of the comparator 34 again. According to the comparator output signal S34, the third time point t13 is signaled to the controller 31, wherein the time point is when the driving voltage V GS It occurs when the voltage drops below the first voltage level V1.

[0070] Based on the driving voltage V GS , the time difference between the second time point t12 and the third time point t13, and based on the predetermined capacitance value C GS , the controller 31 can then evaluate the resistance value R of the internal resistor 12 GS .

[0071] The controller 31 may be designed to output a status signal S after each inspection process. STATUS , the status signal indicates whether the check is performed without error or whether an error has occurred, wherein when the capacitance value C GS Or the resistance value R GS If the transistor assembly 1 is outside the respectively expected range (see (1a) and (1b)), an error is assumed. When a fault is detected, a higher-level controller (not shown) can take appropriate measures, such as interrupting the supply voltage applied to the series circuit of the transistor assembly 1 and the load Z in an appropriate manner.

[0072] Fig.10 An example of a power supply circuit 5 is shown, which is designed to generate a first power supply voltage V of the driver circuit 2 based on a load power supply voltage V+. SUP1 and the second power supply voltage V of the inspection circuit 3 SUP2 In this example, the two supply voltages V SUP1 , V SUP2 Higher than the load power supply voltage V+, where the first power supply voltage V SUP1 can be used on the first power supply capacitor 541, the second power supply voltage V SUP2Can be used on the second power supply capacitor 542. The boost converter having an inductor 53 and a first switch 51 obtains a load power supply voltage V+ and provides a charging current I53 for two capacitors 541 and 542. The charging current I53 provided by the boost converter flows to the power supply capacitors 541 and 542 through corresponding switches 551 and 552. The controller 56 drives the switch 51 and switches 551 and 552 of the boost converter, one of which is connected between the boost converter and the first power supply capacitor 541, and the other is connected between the boost converter and the second power supply capacitor 542. The switch 551 connected between the boost converter and the first power supply capacitor 541 is also referred to as the first charging switch below, and the switch 552 connected between the boost converter and the second power supply capacitor 542 is also referred to as the second charging switch below.

[0073] The controller 56 obtains, for example, a voltage representing the first supply voltage V SUP1 The first supply signal S VSUP1 , represents the second supply voltage V SUP2 The second supply signal S VSUP2 and a current signal S representing the charging current provided by the boost converter I53 . Current measurement signal S I53 This can be done, for example, by measuring the resistor 52 ( Fig.10 The voltage V52 on the power supply voltage V can be obtained by using a conventional voltage sensor. SUP1 , V SUP2 Get the power signal S VSUP1 , S VSUP2 .

[0074] Whenever the switch 51 of the boost converter is turned on by the controller 56 via the corresponding control signal S51, energy is stored in the inductor 53 of the boost converter. When the switch 51 is turned off, the energy is released via at least one of the first and second charging switches 551, 552 and the corresponding storage capacitors 541, 542. According to an example, the controller 56 is designed to turn on at least one of the two charging switches 551, 552 by the corresponding control signals S551, S552 before the switch 51 of the boost converter is turned off, so that the discharge current path is always available for the inductor 53.

[0075] The controller is designed to: For example, whenever the two power supply voltages V SUP1 , V SUP2 When at least one of the power supply voltages V is lower than the corresponding set point, the boost converter is started. "Activating the boost converter" means repeatedly turning on and off the switch 51. When the boost converter is activated, the power supply capacitors 541, 542 (having a power supply voltage V lower than the corresponding set point) are connected to the power supply capacitors 541, 542. SUP1 , VSUP2 ) can be continuously turned on or turned on or off in a beat until the power supply voltage rises to the corresponding set point. Of course, a hysteresis can be provided when charging the power supply capacitors 541 and 542 so that when the two power supply voltages V SUP1 , V SUP2 The boost converter is always activated when at least one of the two supply voltages V SUP1 , V SUP2 When one of the voltages or both voltages rise up to the corresponding upper threshold, the boost converter is deactivated again.

[0076] According to one example, the two charging switches 551, 552 are each implemented as a MOSFET, such as an n-MOSFET, and are interconnected so that they prevent the corresponding supply capacitors 541, 542 from being charged in the off state (i.e., in the cut-off state). When the two charging switches 551, 552 are implemented as MOSFETs, according to one example, diodes 571, 572 are connected in series with each of the two charging switches 551, 552. Each of the two diodes 571, 572 is connected in reverse series with the body diode (not shown) of the MOSFETs 551, 552 connected respectively, so that when the MOSFETs 551, 552 are turned on, the corresponding power supply capacitors 541, 542 are prevented from being discharged through the MOSFETs in any case.

[0077] according to Fig.11 In the example shown, an external resistor 25 can be connected between the control terminals G and S of the transistor assembly 1, wherein the resistor 25 should ensure that the two control terminals G and S are at approximately the same potential when the drive circuit is deactivated, so that the first control terminal G does not float. When the internal resistor is intact, the resistance value R of the external resistor 25 is S Much lower than the internal resistance R GS In order to prevent the external resistor 25 from affecting the inspection of the internal capacitor 11 and the internal resistor 12, according to one example, another switch 36 is provided, which is connected in series with the external resistor 25 and is driven by the controller 31 of the inspection circuit 3. In this example, the controller 31 is designed to: during the inspection process, that is, during the first change and the second change of the charging state of the internal capacitor 11, the switch S36 is opened, so that during the first change of the charging state, the charging current I3 basically only flows into the internal capacitor 11, and during the second change of the charging state, the internal capacitor 11 is basically discharged only through the internal resistor 12.

[0078] According to one example, checking the functionality of the transistor assembly 1 also includes checking the external resistor 25. The external resistor 25 can be checked in the same way as the internal resistor 12. Such an example is Fig.12 To check the external resistor 25, the internal capacitor 11 is charged, for example, by a charging current I3 until the control voltage V GS During the charging process, for example, the switch 36 is opened, so that the charging current I3 flows substantially only into the internal capacitor 11 .

[0079] By driving the voltage V GS After reaching the predetermined voltage level V2′, the charging process ends and the switch 36 is closed, so that the internal capacitor 11 is discharged through the parallel circuit of the internal resistor 12 and the external resistor 25. This change in the charging state of the internal capacitor 11 due to the discharge through the internal resistor 12 and the external resistor 25 is also referred to as a change to the third charging state hereinafter. Since the resistance value of the external resistor 25 is significantly lower than the resistance value of the internal resistor 12, the discharge process is basically controlled by the resistance value R of the external resistor 25. S Corresponding to reference Figure 8 Explanation of the example, determine until the drive voltage V GS The time period required to drop from a specified voltage level V2' to another predetermined voltage level V1', wherein the time period and the predetermined voltage levels V1', V2 and the capacitance value C are taken into account. GS , the resistance value of the external resistor 25 can be determined. Fig.12 The capacitance value C is determined during the charging process of the internal capacitor 11 shown GS Specifically, based on the previous Figure 8 In addition, it is also possible to first perform the Figure 8 The inspection process described in this way can also be used to obtain the capacitance value C GS To check the external resistor 25.

[0080] Fig.13 Shows Fig.11 A variation of the inspection circuit 3 shown in FIG. Fig.13 In the example shown in FIG. 3 , a resistor 37 exists instead of a current source, and when the switch 33 is closed, the internal capacitor 11 is charged through the resistor 37. Figure 7, 9, 10, 11 and 13, a resistor 21 (which is usually called a gate series resistor) can be connected between the output of the driver circuit 2 and the first drive control terminal G. When the transistor component 1 is driven on or off by the driver circuit 2, the resistor 21 affects the magnitude of the current flowing to or from the internal capacitor 11. The inspection circuit 3 can be connected to the drive control input so that the series resistor 21 is located between the output of the driver circuit 2 and a node, and the inspection circuit 3 feeds the charging current I3 at this node. In this case, the series resistor 21 does not affect the charging process of the internal capacitor 11. Fig.13 As shown, the series resistor 21 can also be connected between the first control terminal G and the node feeding the charging current I3 of the test circuit 3. In this case, the series resistor 21 affects the charging process of the internal capacitor 11, and the resistor 37 in the test circuit 3 can also be omitted.

[0081] The checking circuit 3 may be implemented as an integrated circuit. In this case, an external resistor 41 may be additionally provided in parallel with the resistor 37. The external resistor 41 may be used to define the charging current I3 that flows when the switch 33 is closed.

[0082] exist Fig.14 It is shown that Fig.13 An example of an inspection method performed by the circuit shown in Fig.14 The driving signal S33 and the driving voltage V of the switch 33 are shown. GS In this method, the inspection process starts at the initial time point t20, at which the switch 33 is closed, thereby driving the voltage V GS In this example, the drive voltage V GS according to

[0083]

[0084] It grows exponentially, where the time constant τ2 of this exponential increase is given by

[0085] τ2=R·C GS (7)

[0086] Here, R represents the resistance value of a resistor or a resistor network connected between the switch 33 and the first drive control terminal G. The resistor network may include the series resistor 21, the resistor 37 of the test circuit 3 and the external resistor 41 or any combination of these resistors.

[0087] According to Figure 8 In the same way, according to Fig.14 The method, for example, proposes to measure the time period between a first time point t21 and a second time point t22, wherein the first time point t21 is a time period when the driving voltage V GSThe time point at which the first voltage level V1 is reached, and the second time point t22 is the driving voltage V GS When the voltage levels V1, V2 and the time difference t22-t21 between the first and second time points are known, the internal capacitance C can be determined according to the exponential charging characteristic curve when the resistance value R of the resistor network is known. GS The second change in the state of charge of the internal capacitor 11 can be made in the method in accordance with Figure 8 The same method as described is carried out in order to estimate the resistance value R of the internal resistor 12 in this way. GS .

[0088] As in Fig.11 As in the example shown in Fig.13 The circuit shown in FIG. 1 may also have an external resistor between the control terminals G, S; however, the resistor Fig.13 Not shown.

[0089] Fig.15 Shows Fig.13 A variation of the circuit shown. Fig.15 In the circuit shown, the test circuit 3 includes a capacitive storage circuit 37 having a storage capacitor 373, a resistor 372 and a charging switch 371, wherein the series circuit of the charging switch 371, the resistor 372 and the storage element 373 is connected between the other terminal for the power supply potential and the second drive terminal (source terminal S), so that the second power supply voltage V SUP2 The charging switch 33 of the internal capacitor 11 is connected to a node between the charging switch 317 of the capacitive storage circuit 37 and the resistor 372 .

[0090] The charging switch 371 of the capacitive storage circuit 37 is controlled by the controller 31. In the inspection circuit, before the inspection process, the storage capacitor 373 is charged to the second power supply voltage V by closing the charging switch 371. SUP2 Thereafter, the charging switch 371 of the capacitive storage circuit 37 is opened, and the charging switch 33 for the internal capacitor 11 is closed, so that the internal capacitor 11 is connected in parallel with the series circuit of the storage capacitor 373 and the resistor 372, thereby charging the internal capacitor 11.

[0091] Fig.16 The drive signal S33 and the drive voltage V of the switch 33 are shown. GS The timing diagram of FIG. 1 shows the charging process starting at time t30. Fig.15 and Fig.16 In, V CCrepresents the voltage on the series circuit having the storage capacitor 373 and the resistor 372. When the charging switch 33 between the storage capacitor 373 and the internal capacitor 11 is closed, the driving circuit V GS Rising, storage capacitor C C The voltage V CC The capacitance C C The voltage V CC The drop and drive voltage V GS The rise occurs exponentially, but this Fig.16 Not shown.

[0092] exist Fig.16 In the example shown, the first change in the charge state of the internal capacitor 11 includes charging the internal capacitor 11, wherein in order to determine the capacitance value C GS , for example, until the drive voltage V GS The time period from the first voltage level V1 to the second voltage level V2. After knowing these voltage levels V1, V2, the determined time period and the storage capacitor C C The capacitance value of the internal capacitor 11 can be determined by GS .

[0093] exist Fig.15 In the example shown, for example, the storage capacitor 373 is selected so that its capacitance value C C When the internal capacitor 11 has no error, the capacitance value C of the internal capacitor 11 is GS The capacitance value C of the storage capacitor 373 is C For example, the capacitance value C of the intact internal capacitor 11 is GS 0.5 to 10 times.

[0094] Fig.17 Shows Fig.16 A variation of the inspection circuit shown. Fig.17 In the inspection circuit 3 shown, the resistor 372 is omitted, and the storage capacitor 373 is selected so that its capacitance value C C The capacitance C is significantly lower than that of the intact internal capacitor 11. GS . Fig.18 A method for testing the functionality of a transistor assembly 1 using the test circuit 3 is shown in FIG. Fig.18 The time curves of the following are shown: the drive signal of the charging switch 33 connected between the capacitive storage circuit 37 and the first drive terminal G, the drive signal S371 of the charging switch 371 of the capacitive storage circuit 37 and the drive voltage V GSIn this method, the controller 31 complementarily drives the two charging switches 371, 33, wherein each time the charging switch 371 is closed, the storage capacitor 373 is charged, and each time the switch 33 is opened, the storage capacitor 373 is discharged in the direction of the internal capacitor 11. It can be approximately assumed that each time the switch 33 is closed, approximately the same amount of charge is transferred to the internal capacitor 11, thereby increasing the driving voltage V GS To check the capacitance C GS , it is now possible to determine, for example, the permissible control voltage V GS The time period required for the first voltage level V1 to rise to the second voltage level V2 can be calculated as follows: GS The number of charging cycles required to increase the voltage value from the first voltage value V1 to the second voltage value V2. When the frequency at which the two charging switches 371, 33 are driven and the two voltage levels V1, V2 are known, the capacitance value C can be determined based on the number of these charging cycles or based on the measured time period. GS .

[0095] The second change in the charging state of the internal capacitor 11 may occur in the same manner as in the above method, so that the resistance value R of the internal resistor 12 is GS It is possible to know the determined capacitance value C GS is determined or evaluated in the same manner as above.

[0096] Fig.19 Shows Fig.17 A variation of the circuit shown. Fig.19 The circuit has a charge pump 38 which is based on the first power supply voltage V SUP1 The storage capacitor 381 is charged in a clocked manner and then discharged in the direction of the internal capacitor 11. The charging capacitor 381 is connected to the first drive terminal G, for example, via a rectifying element, for example a diode 37. In addition, the terminal of the capacitor 381 facing away from the rectifying element 37 is connected to the first supply potential V via a first switch 382. SUP1 The first power supply voltage V SUP1 Another rectifier element 384 is also connected between the terminals.

[0097] The two switches 382 and 383 are controlled by the controller 36 in a complementary manner, wherein whenever the second switch 383 is closed, the charging capacitor 381 is charged to the first power supply voltage V SUP1 When the second switch 383 is opened and the first switch 382 is closed, the charging capacitor 381 is discharged in the direction of the internal capacitor 11. The first change in the charging state of the internal capacitor 11 is in accordance with Fig.18The same method as described above can be used in accordance with the reference Fig.18 The same method as described above is used to determine the capacitance value C GS .

[0098] As described above, in order to check the functionality of the transistor assembly 1, in addition to the internal capacitance 11 and the internal resistance 12, the presence or resistance value of the external resistor 25 can also be checked. The check of this external resistor 25 can be carried out in a separate check cycle, depending on Fig.12 However, it is also possible to check the external resistor 25 in the same check cycle as the internal resistor 12. An example of this is Fig. 20 Shown in.

[0099] In accordance with Fig. 20 In the example of , it is proposed that after the internal capacitor 11 has been charged to the second voltage level V2, a second change in the charging state of the internal capacitor 11 is performed, which is achieved by first discharging the internal capacitor 11 only via the internal resistor 12. Fig. 20 In the drive control voltage V GS The second change is shown between the second time point t52 and the third time point t53 at which the second voltage level V2 is reached, wherein the third time point t53 represents the driving voltage V GS According to the second and third voltage levels V2, V3 and according to the time difference between the third time point t53 and the second time point t52 and after knowing the capacitance value C determined in advance GS When the resistance value R of the internal resistor 12 can be evaluated GS .

[0100] exist Fig. 20 The method shown also proposes that at time t54, an external resistor 25 is connected and the control voltage V GS The time difference between the time points t55 and t54 is known and the driving voltage V GS The external resistor 25 can be evaluated at the difference between the voltage values ​​at these time points t54, t55. Fig. 20 In the example shown, the evaluation of the external resistor 25 is performed after the evaluation of the internal resistor 12. However, this is only an example. It is also possible to first switch on the external resistor 25 to evaluate the external resistor 25 and then deactivate the external resistor again to evaluate the internal resistor 12.

[0101] In addition, Fig. 20 In the example shown, the LS switch 22 of the driver circuit 2 can also be evaluated. For this purpose, the LS switch 22 is switched on for a certain period of time, for example. Fig. 20In the example shown in FIG. 1 , the internal capacitor 11 is discharged during the time period so that V GS The change in the state of charge of the internal capacitor 11 is referred to as the fourth change in the state of charge. The time period during which the LS switch 22 is closed is selected so that the control voltage V GS does not drop to the on-level V ON Alternatively, the voltage can be set so that the control voltage V GS The voltage will drop and the time period required for this can be measured. GS The LS switch 22 does not drop by a predetermined value within a predetermined on-time, or the control voltage V GS If the time required to drop to the predetermined value is longer than the predetermined period of time, it indicates that the LS switch 22 is faulty.

[0102] exist Fig. 20 In the example shown, after charging the internal capacitor, the internal resistor 12 is first checked, then the LS switch 22 is checked, and then the external resistor 25 is checked. The first change in the charging state of the internal capacitor is followed by a second change in the charging state, then a fourth change in the charging state, and then a third change in the charging state. However, this is only an example. These changes in the charging state and the related checks on the internal resistor 12, the external resistor 25, and the LS switch 22 may be performed in any order.

Claims

1. A method for checking the functionality of a transistor component (1), wherein the method comprises: a first change in the charge state of an internal capacitance (11) present between the control terminals G, S of the transistor assembly, wherein the first change comprises charging the internal capacitance with a constant charging current; Based on the first change in the state of charge, a capacitance value (C GS ); a second change of the charging state of the internal capacitor (11), wherein the second change comprises discharging the internal capacitor only through the internal resistor so that the drive voltage applied between the drive terminals G, S decreases in the direction of the on-level; as well as Based on the determined capacitance value (C GS ) and the second change in the charge state, evaluating the resistance value (R GS ).

2. The method according to claim 1, in, The transistor component (1) has a threshold voltage (Vth), and The first change is performed on the charging state of the internal capacitor (11) so that the driving voltage (V GS ) and the threshold voltage (Vth) increases.

3. The method according to claim 2, in, When the driving voltage (V GS ) has the on-level (V ON ), the first change and the second change are performed on the charging state of the internal capacitor (11).

4. The method according to any one of claims 1 to 3, wherein: Determine the capacitance value (C GS )include: A time period is measured during the first change of the charging state, during which the driving voltage (V GS ) changes from a first defined voltage level (V1) to a second defined voltage level.

5. The method according to claim 1, wherein: The first change to the charging state includes: A substantially constant voltage (V) is applied to a series circuit having the internal capacitor (11) and the charging resistor (37). SUP2 ).

6. The method according to any one of claims 1 to 3, in, The first change in the charge state comprises gradually charging the internal capacitance (11) by means of charging pulses, and Wherein, the capacitance value (C GS ) comprises during said first change to said charging state one of the following: Determine a time period during which the drive control voltage (V GS ) from a first defined voltage level (V1) to a second defined voltage level; or Determine a plurality of charging pulses, through which the driving voltage (V GS ) changes from the first defined voltage level (V1) to the second defined voltage level.

7. The method according to claim 6, wherein: Evaluating the resistance (12) between the drive control terminals G and S comprises: Determine a time period during which the drive control voltage (V GS ) changes from a third defined voltage level to a fourth defined voltage level.

8. The method according to claim 7, wherein: The third defined voltage level is equal to the first defined voltage level (V1), and the fourth defined voltage level is equal to the second defined voltage level (V2).

9. The method according to any one of claims 1 to 3, further comprising: a third change to the charge state of the internal capacitor (11) before or after the second change to the charge state; as well as Based on the third change in the state of charge, evaluating the resistance value of an external resistor (25) connected between the control terminals G, S, The third change to the charging state includes discharging the internal capacitor (11) through the internal resistor (12) and the external resistor (25).

10. The method according to any one of claims 1 to 3, further comprising: a fourth change to the charge state of the internal capacitor (11) before or after the second change to the charge state; as well as evaluating the functionality of a driver circuit (2) connected to the control terminals G, S, The fourth change to the charging state comprises discharging the internal capacitor (11) through an electronic switch (22) of the driver circuit (2).

11. An electronic circuit, the electronic circuit being designed to: to be connected to the control terminals G, S of the transistor assembly (1); performing a first change in the charge state of an internal capacitance (11) present between the drive control terminals G, S of the transistor assembly, wherein the first change comprises charging the internal capacitance with a constant charging current; Based on the first change in the charging state, a capacitance value (C GS ); performing a second change in the charge state of the capacitor (11) between the drive terminals G, S of the transistor component, wherein the second change comprises discharging the internal capacitor only through the internal resistor so that the drive voltage applied between the drive terminals G, S decreases in the direction of the on-level; Based on the determined capacitance value (C GS ) and the second change of the charging state, determining the resistance value (R GS ).

12. The electronic circuit according to claim 11, wherein the electronic circuit is designed to: perform the first change of the charge state of the internal capacitor (11) so that the drive control voltage (V GS ) and the threshold voltage (Vth) of the transistor component (1) increases.

13. The electronic circuit according to claim 11 or 12, wherein the electronic circuit is designed such that: when the driving control voltage (V GS ) has the on-level (V ON ), the first change and the second change are performed on the charging state of the internal capacitor (11).

14. The electronic circuit according to claim 11 or 12, wherein, in order to determine the capacitance value, the electronic circuit is designed to measure a time period during a first change in the charge state, during which the control voltage (V GS ) changes from a first defined voltage level (V1) to a second defined voltage level.

15. The electronic circuit according to claim 14, wherein, in order to achieve the first change in the charging state, the electronic circuit is designed to: apply a substantially constant voltage (V ) to a series circuit having an internal capacitor (11) and a charging resistor (37). SUP2 ).

16. The electronic circuit according to claim 11 or 12, For the first change in the charge state, the electronic circuit is designed to charge the internal capacitor (11) stepwise by means of charging pulses, and For determining the capacitance value (C GS ), the electronic circuit is designed as follows: Determine a time period during which the drive control voltage (V GS ) from a first defined voltage level (V1) to a second defined voltage level; or Determine a plurality of charging pulses, through which the driving voltage (V GS ) changes from the first defined voltage level (V1) to the second defined voltage level.

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