Electronic circuit with dual voltage supply circuit

Abstract

Disclosed herein is an electronic circuit having a dual voltage supply circuit. The electronic circuit includes: an output configured to be connected to a load; and first and second power supply circuits, respectively, connected to the output. The first and second power supply circuits each include: a power supply input configured to receive a respective input voltage; a first circuit node; a first electronic switch connected between the output and the first circuit node; a first rectifier element connected in parallel with the first electronic switch; at least one second electronic switch connected between the power supply input and the first circuit node; at least one second rectifier element connected in parallel with the at least one second switch, wherein the at least one second rectifier element and the first rectifier element are connected in anti-series with each other; and a control circuit. The control circuit is configured to drive the first and second switches and to receive a power supply voltage from the first circuit node at the power supply input.

Description

Technical Field

[0001] The present description relates to an electronic circuit having a dual voltage supply circuit for powering a load. Background Art

[0002] For safety reasons, for example in the automotive sector, two separate supply voltages can be used for the voltage supply of safety-critical electronic arrangements (loads), wherein if one of the supply voltages fails, it can be ensured that the load is supplied via the other supply voltage.

[0003] An example of an electronic circuit suitable for supplying a load with one of two supply voltages includes: a first supply voltage input designed to receive the first supply voltage; a second supply voltage input designed to receive the second supply voltage; and an output designed to be connected to the load. The circuit also includes two rectifier elements: a first rectifier element connected between the first supply voltage input and the output; and a second rectifier element connected between the first supply voltage input and the output. The two rectifier elements are connected in anti-series such that no current flows between the two supply voltage inputs, and the load is always powered by the higher of the two supply voltages.

[0004] However, this circuit cannot detect possible faults, such as an interruption in one of the rectifier components. Such a fault would be indistinguishable from an interruption in the supply voltage. Therefore, there is a need for an electronic circuit that can reliably supply one of two supply voltages to a load and detect possible faults in the circuit. Summary of the Invention

[0005] One example relates to an electronic circuit. The electronic circuit includes an output designed to be connected to a load; and a first power supply circuit and a second power supply circuit, each connected to the output. The first power supply circuit and the second power supply circuit each have: a power supply input designed to obtain a corresponding input voltage; a first circuit node; a first electronic switch connected between the output and the first circuit node; a first rectifier element connected in parallel with the first electronic switch; at least one second electronic switch connected between the power supply input and the first circuit node; at least one second rectifier element connected in parallel with the at least one second switch, wherein the at least one second rectifier element and the first rectifier element are connected in anti-series with each other; and a control circuit. The control circuit is designed to drive the first switch and the second switch and obtain the power supply voltage from the first circuit node at the power supply input. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following examples are described with reference to the accompanying drawings. The drawings are intended to illustrate certain principles and therefore only show aspects necessary for understanding those principles. The drawings are not drawn to scale.

[0007] Figure 1 An example of an electronic circuit having a dual power supply circuit is shown;

[0008] Figure 2A and 2B shows an example for realizing a first switch which can be used in a power supply circuit, respectively;

[0009] Figure 3A and 3B An example for realizing a second switch that can be used in a power supply circuit, respectively, is shown;

[0010] Figure 4 Examples of control circuits that can be used in power supply circuits are shown;

[0011] Figure 5 An example of a voltage supply circuit in a control circuit is shown;

[0012] Figure 6 Another example of an electronic circuit having two power supply circuits is shown;

[0013] Figure 7 Shown Figure 6 A modification of the electronic circuit shown; and

[0014] Figure 8 It shows that the Figure 6 and Figure 7 An example of a control circuit used in a power supply circuit. DETAILED DESCRIPTION

[0015] In the drawings, the same reference numerals denote the same features. It goes without saying that, unless explicitly stated otherwise, the features of the various exemplary embodiments described herein may be combined with one another.

[0016] Figure 1 An example of an electronic circuit is shown, designed to supply a supply voltage VOUT, also referred to below as an output voltage, to a load Z. Load Z can be any electrical or electronic load, particularly loads including safety-related circuits, such as microcontrollers and control circuits for airbags in motor vehicles. To ensure a high degree of safety in the voltage supply to load Z, the electronic circuit is designed to receive two input voltages VIN1 and VIN2 and generate a supply voltage VOUT based on these two input voltages. In this way, if one of the two input voltages VIN1 and VIN2 is missing, the voltage supply to load Z is still guaranteed by one of the two input voltages VIN1 and VIN2.

[0017] The electronic circuit includes an output terminal OUT, which is designed to be connected to a load Z and provide an output voltage VOUT thereto during operation. Furthermore, the electronic circuit includes two power supply circuits, a first power supply circuit 11 and a second power supply circuit 12, each connected to the output OUT. Power supply circuits 11 and 12 each include power supply inputs IN1 and IN2, respectively, designed to receive one of two input voltages VIN1 and VIN2. Hereinafter, the input voltage VIN1 received by the first power supply circuit 11 will be referred to as the first input voltage, and the input voltage VIN2 received by the second power supply circuit 12 will be referred to as the second input voltage.

[0018] The two power supply circuits 11, 12 further include: a first circuit node N11, N12; a first electronic switch S11, S12, which is connected between the output OUT and the corresponding first circuit node N11, N12; and a first rectifier element D11, D12, which is connected in parallel with the corresponding first electronic switch S11, S12. The first electronic switches S11, S12 can be any electronic switches, such as transistors. Examples for realizing these first switches S11, S12 will be described in detail below. The first rectifier elements D11, D12 are, for example, passive rectifier elements. Figure 1 In the example shown, the first rectifier elements D11 and D12 are implemented as pn diodes. However, this is only an example. Other types of passive rectifier elements, such as Schottky diodes, may also be used.

[0019] Reference Figure 1 , each of the two power supply circuits 11, 12 further includes: at least one second electronic switch S21, S22, which is connected between the corresponding power supply input IN1, IN2 and the corresponding first circuit node N11, N12; and at least one second rectifier element D21, D22, connected in parallel with the at least one second switch S21, S22. The second switches S21, S22 can be implemented as any electronic switches, such as transistors. Examples for implementing these second switches S21, S22 will be described in detail below. The second rectifier elements D21, D22 are, for example, passive rectifier elements. In Figure 1 In the example shown, these rectifier elements D21, D22 are bipolar diodes. However, this is only an example. Any other type of passive rectifier element, such as a Schottky diode, may also be used. Figure 1 In the illustrated example, each of power supply circuits 11 and 12 includes a second electronic switch S21 or S22 and a second rectifier element D21 or D22 connected in parallel therewith. However, this is merely an example. According to another example described in detail below, multiple second switches may be connected in series in each of power supply circuits 11 and 12.

[0020] In both power supply circuits 11, 12, first rectifier elements D11, D12 and second rectifier elements D21, D22 are connected in anti-series with each other, so that when first switches S11, S12 and second switches S21, S22 are open (off), no current flows between the corresponding input IN1, IN2 and output OUT in each power supply circuit 11, 12 during fault-free operation of the electronic circuit. According to one example, first rectifier elements D11, D12 and second rectifier elements D21, D22 in power supply circuits 11, 12 are connected in anti-series in such a manner that, with first switches S11, S12 open, current can flow from output OUT to the corresponding first circuit node N11, N12 when the potential VOUT at output OUT is higher than the potential VN11, VN12 at the corresponding first circuit node N11, N12. In this specification, the terms "voltage" and "potential" are used synonymously. For illustration purposes, it is assumed that these voltages or potentials are respectively related to the same reference potential GND (eg ground).

[0021] Reference Figure 1 , the first and second rectifier elements D11, D12, D21, D22 in the two power supply circuits 11, 12 are also connected in anti-series so that, with the second switches S21, S22 open, current can flow from the respective input nodes IN11, IN12 to the first circuit nodes N11, N12 when the respective input voltage VIN1, VIN2 is higher than the voltage or potential VN11, VN12 on the respective first circuit nodes N11, N12. Figure 1 This is achieved in the illustrated power supply circuits 11 , 12 by the fact that in each power supply circuit 11 , 12 the cathodes of the diodes forming the respective first and second rectifier elements D11 , D12 , D21 , D22 are connected to one another.

[0022] Reference Figure 1Each of the two power supply circuits 11, 12 further comprises a control circuit 21, 22. The control circuits 21, 22 are designed to control the respective first switch S11, S12 and the respective second switch S21, S22. The two control circuits 21, 22 can in particular be designed to control the respective first switch S11, S12 depending on the voltage between the output OUT and the respective first circuit node N11, N12. To this end, the control circuits 21, 22 receive the output voltage VOUT (as shown) or a signal (not shown) depending on the output voltage VOUT at a first measurement input 241, 242. According to one example, each control circuit 21, 22 is designed to conductively control the respective first switch VN1, VN2 when the potential VOUT at the output is less than the potential VN1, VN2 at the respective first circuit node N11, N12. Furthermore, the control circuits 21 , 22 are designed to receive a supply voltage VN11 , VN12 at a supply input 231 , 232 from a respective first circuit node N11 , N12 .

[0023] The first and second switches S11, S12, S21, and S22 each have a control terminal for receiving a drive signal DRV11, DRV12, DRV21, and DRV22, and are turned on or off depending on the signal level of the corresponding drive signal DRV11, DRV12, DRV21, and DRV22. The drive signals DRV11, DRV12, DRV21, and DRV22 are generated by the corresponding control circuits 21 and 22.

[0024] exist Figure 1 In the example shown, the circuit elements, circuit nodes and signals of the two power supply circuits 11, 12 are provided with the same reference numerals, which are distinguished only by the subscript "1" or subscript "2" respectively. In the following description, if it is not necessary to distinguish between the two power supply circuits 11, 12, the reference numerals are used. Figure 1 The reference numerals shown in the figures are always without subscripts, so that, for example, reference numeral 1 below denotes one or both of the two power supply circuits 11 , 12 , reference numeral S1 denotes one or both of the first switches S11 , S12 , and so on.

[0025] In accordance with Figure 1 In the electronic circuit of FIG. 1 , the control circuits 2 in the power supply circuit 1 obtain their respective supply voltage VN1 via a first circuit node N1, thereby ensuring that the two control circuits 2 are supplied with power even when one of the two input voltages VIN is missing. A "missing input voltage VIN" may occur, for example, when there is a short circuit with respect to ground at the respective input IN, when a line connection between a voltage source providing the respective input voltage VIN and the input IN is interrupted, or when the input voltage VIN is provided by batteries and one of the batteries is empty.

[0026] According to one example, the control circuits 2 of the two power supply circuits 1 are each implemented so that the control circuit 2 of the power supply circuit that receives the higher input power voltage VIN among the two power supply circuits 1 turns on the first and second switches S1 and S2, respectively, while the control circuit 2 of the power supply circuit that receives the lower input voltage VIN among the two power supply circuits 1 at least turns off the second switch S2. For example, if the first input voltage VIN1 is higher than the second input voltage VIN2, (a) the control circuit 21 of the first power supply circuit 11 turns on the first switch S11 and the second switch S21 in the first power supply circuit 11, and (b) the control circuit 22 of the second power supply circuit 12 turns off the second switch S22 in the second power supply circuit 12. By turning off the second switch S2 in the power supply circuit that receives the lower input voltage of the two input voltages VIN1 and VIN2 at its input, it is possible to prevent a shoot-through current from flowing between the two inputs IN. In the example described above, by turning off the second switch S22 in the second power supply circuit 12, a through current is also prevented from flowing from the first input IN1 to which the higher input voltage of the two input voltages VIN1, VIN2 is applied to the second input to which the lower input voltage of the two input voltages VIN1, VIN2 is applied.

[0027] In the power supply circuit that receives the lower of the two input voltages in the two power supply circuits 1, the associated first switch 1 can be turned on or off. In the example described above, in which the second power supply circuit 12 receives the lower of the two input voltages VIN1 and VIN2, the associated first switch S12 can therefore be (a) turned on or (b) turned off. In the first case (a, S12 is on), the second control circuit 22 receives the output voltage VOUT as the power supply voltage VN12 via the first switch S12. In the second case (a, S12 is off), the second control circuit 22 receives the second input voltage VIN2 as the power supply voltage VN12 via the rectifier element D22 connected in parallel with the second switch S22. With regard to the power loss that occurs, the first case is more favorable because the power loss generated at the turned-on first switch S12 is generally lower than the power loss generated at the second rectifier element D22 in the forward direction.

[0028] Therefore, during normal operation of the circuit, i.e., when both inputs IN have a sufficiently high input voltage VIN, at least two switches are closed: the first and second switches S1 and S2 in the power supply circuit that receives the higher of the two input voltages. Optionally, the first switch S1 in the power supply circuit that receives the lower of the two input voltages is also closed. "Sufficiently high" refers to a voltage VIN that is suitable for supplying power to the load Z and the control circuit.

[0029] One of the two input voltages VIN being higher than the other may be due to one of the two input voltages VIN being missing, or it may be due to the two input voltages VIN being slightly different from each other. The latter is the normal case. If the two input voltages VIN are approximately the same, it is also possible that both control circuits 2 turn on the respective first and second switches S1 and S2, thereby creating a conductive connection between the two inputs IN. However, if the input voltages VIN are equal, this is not a significant issue, as at most only a small compensation current will flow.

[0030] As explained, the first switches S1 in the two power supply circuits 1 can be turned on by the corresponding control circuits 2 as long as there is a sufficient voltage supply to the corresponding control circuits 2. In this case, the control circuits 2 are designed to turn on the associated first switches S1 as soon as these control circuits receive a sufficient supply voltage.

[0031] Alternatively, the control circuit 2 is configured to turn on only the first switch S1 located in the power supply circuit 1 that receives the higher input voltage of the two input voltages VIN. In this case, the control circuit can be configured to compare the corresponding input voltage VIN or the voltage VN1 at the first circuit node N1 with the output voltage VOUT, and to turn on the associated first switch S1 only when the input voltage VIN or the voltage VN1 at the first circuit node N1 is greater than or at least equal to the output voltage VOUT.

[0032] To control the second switch S2, the control circuit 2 is configured, for example, to compare the corresponding input voltage VIN with the output voltage VOUT and to switch the second switch S2 on when the input voltage VIN connected to the input IN of the second switch is higher than or at least equal to the output voltage VOUT. The control circuit receives the input voltage VIN, for example, via another measurement input 25.

[0033] As long as one of the two supply voltages VIN is present, that is, if one of the two supply voltages is missing, the voltage supply to both control circuits 2 is always guaranteed. For example, if the first input voltage VIN1 is missing (i.e., the first input voltage VIN1 is zero), and the second supply voltage VIN2 has a voltage level sufficient to supply the load Z and both control circuits 2, the control circuit 22 in the second supply voltage 12 switches on the corresponding first and second switches S12 and S22, so that the output voltage VOUT approximately corresponds to the second input voltage VIN2 (minus the unavoidable small voltage drop across switches S12 and S22). Via the first rectifier element D11 in the first power supply circuit 11, or via the switched-on first switch S11, the control circuit 21 of the first power supply circuit 11 receives a supply voltage VN11 that approximately corresponds to the output voltage VOUT (minus the forward voltage of the first rectifier element D11). The supply voltage VN12 of the second control circuit 22 approximately corresponds to the output voltage VOUT. Thus, even if one of the two input voltages VIN1 , VIN2 is lost, sufficient power supply voltage is supplied to the two control circuits 21 , 22 .

[0034] According to one example, the control circuits 21, 22 measure the respective input voltages VN11, VN12 via further measurement inputs 251, 252 and, when the respective input voltages VN11, VN12 fall below a predetermined threshold, output a fault signal to a higher-level control unit (shown in dashed lines) via optional communication connections COM1, COM2. In the example explained above (in which the first input voltage VN11 is missing), the control circuit 21 in the first power supply circuit 11 can still output the fault signal via the respective communication connection COM1 despite the absence of the first input voltage VN11, because this communication connection is available due to the presence of a sufficient voltage supply via the first circuit node N11.

[0035] As mentioned above, the first switch S1 can be implemented as any electronic switch. The first switches S1 in the two power supply circuits 1 can be electronic switches of the same type or electronic switches of different types. Figure 2A and 2B Examples of different switch types implemented to implement the first switch S1 are shown in FIG.

[0036] According to an example, Figure 2AAs shown, at least one of the two first switches S1 is implemented as a MOSFET, in particular, as an n-channel normally closed MOSFET (n-channel enhancement MOSFET). The first rectifier element D1 can be the intrinsic body diode of the MOSFET. In the case of an n-channel normally closed MOSFET, the anode of the intrinsic body diode is formed by the source terminal S of the MOSFET, while the cathode of the body diode is formed by the drain terminal D of the MOSFET. The control terminal for obtaining the drive signal DRV1 is formed by the gate terminal G of the MOSFET. In the case of a MOSFET, the drive signal DRV1 is the voltage between the gate terminal G and the source terminal S. When this voltage is above the threshold voltage of the MOSFET, the MOSFET is turned on, and when this voltage is below the threshold voltage of the MOSFET, the MOSFET is turned off.

[0037] In addition to the internal body diode, an external rectifier element, such as a pn diode or a Schottky diode, can optionally be connected between the drain terminal D and the source terminal S in parallel with the internal diode in the MOSFET. The first rectifier element D1 is then formed by connecting the body diode and the external rectifier element in parallel.

[0038] According to an example, the first switches S1 in the two power supply circuits 1 are respectively n-channel normally closed MOSFETs. In this case, the drain terminals D of the two MOSFETs are connected to the output OUT of the circuit to realize the polarity of the first rectifier element D1, as shown in FIG. Figure 1 This interconnection of two MOSFETs used as the first switch S1 may be referred to as a common drain configuration.

[0039] According to another example, at least one of the first switches S1 is implemented as an IGBT, such as Figure 2B As shown. The control input of the IGBT is formed via the gate terminal. In the case of an IGBT, the drive signal is the voltage between the gate terminal G and the emitter terminal E. When an IGBT is used as the first switch S1, the first rectifier element D1 can be, for example, an external rectifier element connected between the collector terminal C and the emitter terminal E of the IGBT in such a way that when a positive voltage is applied between the emitter E and the collector C, current flows through the rectifier element D1. When the rectifier element D1 is implemented as a diode, this means that the anode of the diode is connected to the emitter E of the IGBT, while the cathode of the diode is connected to the collector C of the IGBT. The diode is, for example, a pn diode or a Schottky diode.

[0040] At least one of the first switches S1 is implemented as Figure 2A MOSFET as shown, or as Figure 2BOf course, any other type of transistor may be used for at least one of the first two switches S1, such as a bipolar junction transistor (BJT), a junction field effect transistor (JFET), or a high electron mobility transistor (HEMT), to name a few examples.

[0041] The above description of the implementation of the first switch S1 in the two power supply circuits 1 applies in a corresponding manner to the implementation of the at least one second switch S2 in the two power supply circuits 1. That is, the at least one second switch S2 in at least one of the two power supply circuits 1 may be as follows: Figure 3A As shown, it is implemented as a MOSFET, Figure 3B , or as any other transistor, such as a BJT, a JFET, or a HEMT. When a plurality of second switches are used in the power supply circuit, these second switches may be switches of the same type or switches of different types.

[0042] Figure 4 A block diagram showing an example of one of two control circuits 2 is shown, wherein the control circuit 2 is capable of Figure 4 The block diagram shown is implemented in two power supply circuits 1. Figure 4 The block diagram shows the functional blocks of the control circuit 2, but does not show the specific implementation. Figure 4 The functional blocks shown can be implemented in various ways. According to one example, dedicated circuits are used to implement these functional blocks. According to another example, hardware and software are used to implement the control circuit. Thus, for example, the control circuit 2 can include a microcontroller and software executed by the microcontroller.

[0043] refer to Figure 4 The control circuit 2 includes a driver 4 designed to generate drive signals DRV1, DRV2 for a first switch S1 and at least one second switch S2, which are driven by the controller 3. The voltage monitoring circuit 5 obtains an output voltage VOUT and a voltage VN1 at a first circuit node N1 and is designed to provide signals representing these voltages VOUT, VN1 to the controller 3 so that the controller 3 can drive the first and second switches S1, S2 as a function of these voltages VOUT, VN1 in the manner described above.

[0044] Reference Figure 4 The control circuit 2 further comprises a voltage supply circuit 6 which obtains a voltage VN1 at the first circuit node N1 and is designed to generate at least one internal supply voltage VSUP for each functional block based on the voltage VN1 at the first circuit node N1.

[0045] An example of such a voltage supply circuit 6 is Figure 5, which is further illustrated in detail in FIG. The voltage supply circuit includes an evaluation circuit 63 and a voltage generation circuit 64 and is designed to generate an internal supply voltage VSUP for the control circuit 2 only when a voltage VN1 obtained at the power supply input 23 from the first circuit node N1 is greater than a predetermined threshold value. To this end, the evaluation circuit 63 obtains a voltage VN1 or a voltage proportional to the voltage VN1 from the voltage components 61 and 62 and compares the obtained voltage with a threshold value. The evaluation circuit 63 is also designed to enable or disable the voltage generation circuit 64 for generating the internal supply voltage VSUP, wherein the evaluation circuit 63 enables the voltage supply circuit 64 when the obtained voltage value is greater than the predetermined threshold value. To generate the internal supply voltage VSUP, the voltage generation circuit 64 obtains, for example, the voltage VN1 via the power supply input 23.

[0046] As described above, each control circuit 2 can be designed to drive the associated first switch S1 to conduct once it has received a sufficient supply voltage, or once it has received a sufficient supply voltage and the potential VN1 at the first circuit node N1 is higher than the potential VOUT at the output OUT. In the steady state, i.e., after a certain time has passed since the two input voltages VIN appear, this means that the first switch S1 of the power supply circuit 1 that receives the higher of the two input voltages VIN is always turned on.

[0047] The operating phase between applying the input voltage VIN and reaching the steady-state operating state is hereinafter referred to as the "startup phase." The control circuit 2 can be implemented with different functions. Depending on the existing functions of the control circuit 2, different operating conditions may occur during the startup phase. Several examples are described below, assuming that both power supply circuits 1 are operating normally and that the power supply voltage VIN applied to their inputs IN is sufficient to put the control circuit 2 into an operationally ready state. In this operationally ready state, the control circuit 2 is capable of controlling the first and second switches S1 and S2.

[0048] In a first example, assume that during the startup phase, two supply voltages VIN are provided at input IN with a temporal offset, i.e., there is a time delay between the presence of one of the two input voltages VIN and the presence of the other. Since the output voltage VOUT is initially zero, the control circuit 2 of the two control circuits 2 that first obtains a sufficient supply voltage VN1 via the second rectifier element D2 turns on the associated switch S1. For example, if the first input voltage VIN1 is higher than the second input voltage VIN2, the first control circuit 21 turns on the first switch S11, resulting in the output voltage VOUT approximately corresponding to the first input voltage VIN11. After the first switch S11 in the first power supply circuit 11 is turned on, the control circuit 22 in the second power supply circuit 12 also obtains a sufficient voltage supply via the associated first rectifier element D12. As described above, the control circuit 22 can be designed to turn on the first switch 12 immediately after obtaining a sufficient supply voltage, or only when the associated input voltage VIN2 or the voltage VN1 at the first circuit node N12 is higher than the output voltage VOUT.

[0049] If the later of the two supply voltages VIN is lower than the earlier of the two supply voltages VIN, the second switch S2 and, optionally, the first switch S1 of the power supply circuit 1 that receives the lower input voltage VIN remain off. If, in the example described above, the second input voltage VIN2 is also lower than the first supply voltage VIN1, at least the second switch S22 of the second power supply circuit 12 remains off because the output voltage VOUT, which approximately corresponds to the first input voltage VIN1, is higher than the second input voltage VIN2. If the second switch S22 of the second power supply circuit 12 is turned on, a through-current would flow between the inputs IN1 and IN2, which is undesirable.

[0050] However, if the later-appearing input voltage of the two input voltages VIN is greater than the earlier-appearing input voltage of the two input voltages VIN, the power supply circuit 1 receiving the higher of the two input voltages VIN turns on its associated second switch S2, while the power supply circuit 1 receiving the lower of the two input voltages VIN turns off its associated second switch S2 to prevent a shoot-through current between the two inputs IN. In the above example, if the later-appearing second input voltage VIN2 is also higher than the earlier-appearing first input voltage VIN1, the control circuit 22 in the second power supply circuit 12 recognizes that the voltage VN12 at the first circuit node N12, or the second input voltage VIN2, is higher than the output voltage VOUT and turns on its associated second switch S22. As a result, the output voltage VOUT rises to approximately the value of the higher second input voltage VIN2. Since the voltage VN11 at the first circuit node N11, or the first input voltage VIN1, is lower than the output voltage VOUT, the control circuit 21 of the first power supply circuit 11 then turns off its associated second switch S21. The first switch S11 in the first power supply circuit 11 may be turned off together with the second switch S22 , or may remain turned on in order to supply the control circuit 21 in the first power supply circuit 11 with as little loss as possible with respect to the output voltage VOUT.

[0051] Furthermore, various diagnostic functions can be implemented in the control circuit 2. Various examples of such diagnostic functions are described below, wherein these diagnostic functions can be implemented in one or both of the two control circuits 2.

[0052] As mentioned above, one of the possible diagnostic functions is related to the input voltage VIN. Therefore, at least one of the control circuits 2 can be designed to compare the received input voltage VIN with a threshold value and output a corresponding fault signal via the communication output COM if the input voltage VIN is below the predetermined threshold value.

[0053] Another example involves detecting a short circuit between first and second switches S1 and S2. In this example, at least one of the two control circuits 2 is designed to detect a short circuit between the first and second switches S1 and S2. To this end, when the switches are to be turned off by the corresponding drive signals DRV1 and DRV2, the control circuit 2 detects the voltage across the respective first or second switch S1 and S2. If the voltage falls below a predetermined threshold when the switches S1 and S2 are turned off, a short circuit is assumed to have occurred in the respective switch. To detect the voltage across the first switch S1, the control circuit 2 evaluates the difference between the voltages VOUT and VN1 applied to inputs 24 and 23. To determine the voltage across the second switch S2, the control circuit 2 evaluates the difference between the voltages VN1 and VIN available at inputs 23 and 25.

[0054] Yet another example involves detecting an interruption in first and second switches S1 and S2. In this example, at least one of the two control circuits 2 is designed to detect an interruption in the first and second switches S1 and S2. To this end, when the switches are to be switched on by the respective drive signals DRV1 and DRV2, the control circuit 2 detects the voltage across the respective first or second switch S1 and S2. If the voltage when the drive switches S1 and S2 are conducting (when the switches S1 and S2 are closed) exceeds a predetermined threshold, the respective switch is considered to be interrupted. To detect the voltage across the first switch S1, the control circuit 2 evaluates the difference between the voltages VOUT and VN1 applied to the inputs 21 and 23. To determine the voltage across the second switch S2, the control circuit 2 evaluates the difference between the voltages VN1 and VIN available at the inputs 23 and 25.

[0055] According to one example, the control circuit 2 is configured to output a corresponding fault signal via the communication connection COM when a short circuit is detected in one of the two switches S1, S2. According to one example, the control circuit is further configured to turn off or keep the other switch off when a short circuit is detected in one of the two switches S1, S2.

[0056] There may optionally be a communication channel between the two control circuits 2 (in Figure 1 (shown in dashed lines in FIG. ). According to one example, the two control circuits 2 are configured to send a corresponding fault signal to the other control circuit when a short circuit is detected in the associated first switch S1. Furthermore, the control circuit 6 is configured to switch off the associated at least one second switch S2 upon receiving such an error signal, in order to reliably prevent a shoot-through current between the two inputs IN.

[0057] Alternatively or additionally, the superordinate control circuit can switch off at least one second switch in one of the power supply circuits 1 if a short circuit is detected in the first switch S1 of the other power supply circuit 1. If this function is additionally present, redundancy can be achieved.

[0058] A superior control circuit (shown by a dashed line in the figure) coupled to the control circuit 2 via the communication connection COM can take appropriate measures depending on the error signal obtained from the control circuit 2, such as shutting down one or both of the supply voltages VIN.

[0059] Figure 6Another example of an electronic circuit having two power supply circuits 11 and 12 is shown. In this example, the two power supply circuits 11 and 12 each include two second switches S211, S212, S221, and S222, which are connected in series between the respective inputs IN1 and IN2 and the respective first circuit nodes N11 and N12. Associated rectifier elements D211, D212, D221, and D222 are connected in parallel with each of these second switches S211, S212, S221, and S222. Unless a distinction is needed between the second switching elements or second rectifier elements of the first and second power supply circuits 11 and 12, the second switches will be generally referred to as S21 and S22, and the two rectifier elements will be generally referred to as D21 and D22.

[0060] The second rectifier elements D21 , D22 of each power supply circuit 1 are connected in series so that current can flow between the respective input IN and the respective first circuit node N1 when the voltage VIN at the input IN is higher than the voltage VN1 on the first circuit node N1 .

[0061] exist Figure 6 In the example shown, the control circuit 2 is designed to drive the second switches S21, S22 synchronously, ie, to switch them on or off simultaneously. The control of the two second switches of the power supply circuit 1 is similar to that described above according to Figure 1 The driving of a second switch S2 described in the embodiment of FIG. 1 is performed in the same manner.

[0062] The presence of two second switches S21, S22 connected in series and the associated second rectifier elements D21, D22 increases the safety of the electronic circuit. If a short circuit occurs in one of the two second switches S21, S22, while the other switch S21, S22 remains functional, the circuit remains operable.

[0063] According to one example, each of the control circuits 2 obtains a current at a circuit node N2 (where N2 represents a current) via another input 27 located between the two second switches S21, S22. Figure 6 The potential of the voltage present at one of the circuit nodes N21, N22 shown in FIG. In this way, the control circuit 2 can detect the voltage across the two second switches S21, S22 and, in this way, can detect a short circuit or interruption in the two switches S21, S22. For example, if the voltage across the corresponding switch is below a predetermined threshold when the control switch is off, a short circuit is present. For example, if the voltage across the corresponding switch is above a predetermined threshold when the control switch is on, freewheeling is present. According to one example, the control circuit 2 is configured to disconnect the other of the two second switches S21, S22 and / or output a fault signal via a communication connection when a short circuit is detected in one of the two second switches S21, S22.

[0064] Figure 7 Another embodiment of the electronic circuit is shown. In this exemplary embodiment, the power supply circuit 1 comprises current detection devices 71, 72, respectively, which are designed to detect at least one current direction of the output current IOUT1, IOUT2 ​​flowing between the corresponding power supply circuit 11, 12 and the output OUT. The current detection circuits 71, 72 are only Figure 7 Schematically illustrated in FIG. These current detection circuits 71, 72 can be implemented as any conventional current sensor, such as an inductive current sensor, a Hall effect sensor, a sensor using a shunt resistor, etc. The current detection circuits 71, 72 are coupled to the control circuits 21, 22 via current measurement inputs 261, 262. The control circuits 21, 22 are designed within the electronic circuit to take into account the current measurement results provided by the current detection circuits 71, 72 when actuating the respective first switches S11, S12 and at least one second switch. An example is provided below.

[0065] exist Figure 7 In the example shown, the power supply circuit 1 includes two second switches S21 and S22. However, this is only an example. Figure 1 In the embodiment, a current detection circuit 7 (wherein reference numeral 7 represents either one or both of the current detection circuits 71 , 72 ) may also be provided, wherein only one second switch S2 exists in each of the power supply circuits 1 .

[0066] Figure 8 Shown Figure 7 An example of one of the two control circuits 2 in the electronic circuit shown. Figure 4 The control circuit described differs in that the controller 3 is coupled to a current measurement input 26 (wherein reference numeral 26 denotes a current measurement input according to Figure 7 one of the current measurement inputs 261 , 262 of the circuit 7 ) in order to obtain a current measurement signal provided by the corresponding current detection circuit 7 .

[0067] In this example, control circuit 2 is configured, for example, to control at least one of second switches S2 or S21, S22 to be closed when current measurement signal S7 obtained by current detection circuit 7 indicates that the associated output current IOUT has a negative sign, i.e., is flowing from output OUT into the corresponding power supply circuit 1. For example, such an output current IOUT with a negative sign may occur if the voltage ratio at input IN changes, i.e., if the previously lower value of the two input voltages VIN1, VIN2 exceeds the previously higher value of the two input voltages VIN1, VIN2. This will be explained below.

[0068] For illustrative purposes, assume that the first input voltage VIN1 is initially the greater of the two input voltages VIN1 and VIN2. In this case, the first switch S1 and at least one second switch S211, S221 of the first power supply circuit 11 are turned on by the control circuit 21, while at least the second switch S22 of the second power supply circuit 12 is turned off. If the second input voltage VIN2 now exceeds the first input voltage VIN1, the input voltage VIN2 of the second power supply circuit 12 exceeds the potential VOUT at the output OUT, causing the second control circuit 22 to turn on the associated second switch S22. Consequently, the output potential VOUT rises to approximately the value of the now-higher second input voltage VIN2. Consequently, based on the previously turned-on at least one second switch S211, S222 (and optionally the turned-on first switch S11) of the first power supply circuit 11, current from the output OUT can flow in the direction of the first input IN1. This is equivalent to the output current IOUT1 of the first power supply circuit 11 being negative. This negative current flow is detected by the current detection circuit 71, causing the first control circuit 22 to turn off at least one second switch S211, S222 to prevent this current flow. According to one example, in this case, the control circuit 21 also turns off the first switch S11 of the first power supply circuit 11. Alternatively or in addition to the comparison of the input voltages VIN1, VIN2 with the output voltage VOUT described above, the output currents IOUT1, IOUT2 ​​used to control the second switches S21, S22 to be turned off can also be evaluated.

[0069] According to one example, at least one of the control circuits 2 is further configured to control the associated first switch S1 in a pulse-width-modulated manner, depending on a measured value provided by the corresponding current detection circuit, in order to limit the output current IOUT. This current limiting is particularly useful when the load has a capacitance that is charged after the circuit is switched on. During the charging of such a capacitance, high currents (inrush currents) may occur, which in turn lead to high conduction losses in the power supply circuit 1, wherein these high conduction losses can result in high thermal loads on components in the power supply circuit 1. For example, the control circuit 2 is configured to control the associated first switch S1 in a pulse-width-modulated manner when the current level of the output current exceeds a predetermined threshold. According to one example, the time period during which the first switch S1 is pulse-width-modulated or during which the current IOUT is above a predetermined threshold when the first switch S1 is switched on is measured, and the first switch S1 is permanently switched off and / or a fault signal is output when this time period exceeds the predetermined time threshold. In the latter case, a fault in the load, such as a short circuit, can be assumed.

Claims

1. An electronic circuit comprising: an output configured to be connected to a load; as well as A first power supply circuit and a second power supply circuit, each of which is connected to the output and each has: a power input configured to obtain a corresponding input voltage; a first circuit node; a first electronic switch connected between the output and the first circuit node; a first rectifier element connected in parallel with the first electronic switch; at least one second electronic switch connected between the power input and the first circuit node; at least one second rectifier element connected in parallel with at least one second switch, wherein the at least one second rectifier element and the first rectifier element are connected in anti-series with each other; and a control circuit of at least one of the first and second power supply circuits, wherein the control circuit is directly coupled to the first circuit node and to the output, the control circuit being configured to: driving the first electronic switch and the second electronic switch, and A supply voltage is obtained from the first circuit node at a power supply input.

2. The electronic circuit according to claim 1, in, The control circuit of at least one of the first power supply circuit and the second power supply circuit is configured to switch on the corresponding first electronic switch when the potential at the corresponding first circuit node is higher than the potential at the output.

3. The electronic circuit according to claim 1, in, The control circuit of at least one of the first and second power supply circuits is configured to switch on the corresponding first electronic switch as soon as the control circuit obtains a sufficient supply voltage from the first circuit node.

4. The electronic circuit according to claim 1, in, The control circuit of at least one of the first and second power supply circuits is configured to switch on the at least one second electronic switch when the corresponding input voltage is higher than an output voltage at the output.

5. The electronic circuit according to claim 1, wherein At least one of the first power supply circuit and the second power supply circuit further includes: A current measuring device is configured to detect at least one current direction of an output current of the corresponding power supply circuit.

6. The electronic circuit according to claim 5, wherein The control circuit of at least one of the first power supply circuit and the second power supply circuit is configured to: turn off the at least one second electronic switch depending on the detected output current.

7. The electronic circuit according to claim 5, wherein The control circuit of at least one of the first power supply circuit and the second power supply circuit is configured to: when the output current has a predefined first current direction, turn off the at least one second electronic switch according to the detected output current, wherein the detected output current flows from the output into the corresponding power supply circuit.

8. The electronic circuit according to claim 4, wherein The control circuit of at least one of the first power supply circuit and the second power supply circuit is configured to limit the corresponding output current by pulse-width modulated driving of the first electronic switch when the corresponding output current has a predetermined second current direction.

9. The electronic circuit according to claim 1, wherein The control circuit of at least one of the first and second power supply circuits has an internal power supply circuit configured to generate at least one internal supply voltage based on the supply voltage obtained from the first circuit node.

10. The electronic circuit according to claim 9, in, the internal power supply circuit having an evaluation circuit configured to evaluate the supply voltage obtained from the first circuit node, and Therein, the internal power supply circuit is configured to generate the at least one internal supply voltage depending on a result of the evaluation.

11. The electronic circuit according to claim 1, wherein In at least one of the first power supply circuit and the second power supply circuit, the first electronic switch has a MOSFET, and the first rectifier element is a body diode of the MOSFET.

12. The electronic circuit according to claim 11, in, In the first power supply circuit and the second power supply circuit, the first electronic switch is a MOSFET, wherein the MOSFET is an n-type MOSFET, and Wherein, a drain terminal of each of the MOSFETs is connected to the output.

13. The electronic circuit according to claim 1, wherein In at least one of the first power supply circuit and the second power supply circuit, the at least one second electronic switch has a MOSFET, and the at least one second rectifier element is a body diode of the MOSFET.

14. The electronic circuit according to claim 1, wherein The at least one second electronic switch has two second electronic switches connected in series.

15. An electronic circuit comprising: an output configured to be connected to a load; as well as A first power supply circuit and a second power supply circuit, each of which is connected to the output and each has: a power input configured to obtain a corresponding input voltage; a first circuit node; a first electronic switch connected between the output and the first circuit node; a first rectifier element connected in parallel with the first electronic switch; at least one second electronic switch connected between the power input and the first circuit node; at least one second rectifier element connected in parallel with the at least one second electronic switch, wherein the at least one second rectifier element and the first rectifier element are connected in anti-series with each other; as well as A control circuit configured to: driving the first electronic switch and the second electronic switch, and obtaining a supply voltage from said first circuit node at a power supply input, At least one of the first power supply circuit and the second power supply circuit further comprises a current measuring device, and the current measuring device is configured to detect at least one current direction of an output current of the corresponding power supply circuit.

16. The electronic circuit according to claim 15, wherein The control circuit of at least one of the first power supply circuit and the second power supply circuit is configured to: turn off the at least one second electronic switch depending on the detected output current.

17. The electronic circuit according to claim 15, wherein The control circuit of at least one of the first and second power supply circuits is configured to: when the output current has a predefined first current direction, turn off the at least one second electronic switch according to the detected output current, wherein the detected output current flows from the output into the corresponding power supply circuit.

18. An electronic circuit comprising: an output configured to be connected to a load; as well as A first power supply circuit and a second power supply circuit, each of which is connected to the output and each has: a power input configured to obtain a corresponding input voltage; a first circuit node; a first electronic switch connected between the output and the first circuit node; a first rectifier element connected in parallel with the first electronic switch; at least one second electronic switch connected between the power input and the first circuit node; at least one second rectifier element connected in parallel with at least one second electronic switch, wherein the at least one second rectifier element and the first rectifier element are connected in anti-series with each other; as well as A control circuit configured to: driving the first electronic switch and the second electronic switch, and obtaining a supply voltage from said first circuit node at a power supply input, The at least one second electronic switch includes two second electronic switches connected in series.

19. The electronic circuit of claim 18, wherein at least one of the first electronic switch and the second electronic switch comprises a MOSFET transistor.

20. The electronic circuit of claim 18, wherein at least one of the first electronic switch and the second electronic switch comprises an IGBT transistor.

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