Load driving circuit

Abstract

The application provides a load driving circuit. The load driving circuit is used for driving a load, a positive electrode of a power supply of the load is connected with a first power supply, the load driving circuit comprises a first switching element and a second switching element, a first connecting end of the first switching element is used for grounding, a second connecting end of the first switching element is connected with a first connecting end of the second switching element, and a second connecting end of the second switching element is used for connecting a negative electrode of the power supply of the load. The switching elements arranged redundantly improve the reliability of the system, and specific connection relations are designed so as to cooperate with a specific detection module, to feed back the working states of the two switching elements through one port, and to solve the problem of insufficient control reliability of important loads in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of electrical control, and in particular to a load driving circuit. Background Art

[0002] In fields such as industrial control, aerospace, and automotive, there are often critical loads that need to remain reliably on or off. Examples include the start switch of a crane and the main relay switch connecting the positive and negative terminals of a car battery pack. These loads are often crucial to the entire system, and if they become uncontrolled, they can result in serious consequences such as casualties.

[0003] For example, the main relay in a car uses a switch to control the main electrical device. When the switch is closed, the relay is engaged; when the switch is open, the relay is open. However, all electronic components have a certain degree of failure rate. If the switch fails and cannot be opened, or if the MCU controlling the switch malfunctions and continuously outputs the "switch closed" command, the main relay will not open, preventing the entire vehicle from being powered off, posing a significant safety hazard. Therefore, improving the reliability of such load control is a critical issue.

[0004] In summary, the existing technology has the problem of insufficient control reliability of important loads. Summary of the Invention

[0005] The present invention provides a load driving circuit to solve the problem of insufficient control reliability of important loads in the prior art.

[0006] In order to solve the above technical problems, the present invention provides a load driving circuit, which is used to drive a load, the positive power supply of the load is connected to a first power supply, and the load driving circuit includes a first switching element and a second switching element, the first connection end of the first switching element is used for grounding, the second connection end of the first switching element is connected to the first connection end of the second switching element, and the second connection end of the second switching element is used to connect to the negative power supply of the load.

[0007] The first switch element is used to turn on or off in response to a control signal from a controller; the second switch element is used to turn on or off in response to a control signal from a monitoring module; only when it is determined that the controller is in a safe state, the monitoring module outputs a control signal to drive the second switch element to turn on.

[0008] Optionally, the load driving circuit further includes a detection module, and the detection module is used to feed back actual disconnection states of the first switching element and the second switching element.

[0009] Optionally, the detection module includes a semiconductor device, and the working state of the semiconductor device includes a cut-off state, an amplified state and a saturated state; when the first switching element and the second switching element traverse all combinations of on-off states, the working state of the semiconductor device traverses the cut-off state, the amplified state and the saturated state; the detection module only includes one feedback output terminal for feedback of the actual on-off state of the first switching element and the second switching element, and the signal of the feedback output terminal is generated based on the semiconductor device.

[0010] Optionally, when the first switching element is turned off and the second switching element is turned off, the working state of the semiconductor device is an amplification state; when the first switching element is turned on and the second switching element is turned off, the working state of the semiconductor device is a cut-off state; when the first switching element is turned off and the second switching element is turned on, the working state of the semiconductor device is a saturation state.

[0011] Optionally, the semiconductor device is one of a transistor, a MOS tube, a thyristor and an IGBT.

[0012] Optionally, the semiconductor device is an NPN transistor, and the collector of the semiconductor device is configured as the feedback output terminal.

[0013] Optionally, the detection module further includes a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor.

[0014] Among them, the first end of the first resistor is used for grounding; the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the first end of the fifth resistor; the second end of the fifth resistor is used to connect to a second power supply, and the first end of the fifth resistor is also connected to the collector of the semiconductor device; the first end of the third resistor is connected to the first end of the second resistor, and the second end of the third resistor is connected to the base of the semiconductor device, the first end of the fourth resistor is connected to the first end of the second resistor, and the second end of the fourth resistor is connected to the second connection end of the first switching element.

[0015] Optionally, the following electrical parameters meet the following conditions: Ube1=VDD*R1 / (R1+R2+Rd), Ib=(Ub1-Ubeq) / R3, Ic=βIb, (VDD-Uce1) / Rd=(Uc1-Ub1) / R2+Ic, Ube1>Uon, Uce1 <Ube1,Ube2=VDD*(R4 / / R1) / (R4 / / R1+R2+Rd),Ube2<Uon,VBATTERY> VDD.

[0016] Wherein, VBATTERY represents the voltage of the first power supply, VDD represents the voltage of the second power supply, R1 represents the resistance of the first resistor, R2 represents the resistance of the second resistor, R3 represents the resistance of the third resistor, R4 represents the resistance of the fourth resistor, Rd represents the resistance of the fifth resistor, Ubeq represents the base voltage drop of the semiconductor device, β represents the amplification factor of the semiconductor device, Ub1 represents the base voltage of the semiconductor device under the first working condition, Uc1 represents the collector voltage of the semiconductor device under the first working condition, Ue1 represents the emitter voltage of the semiconductor device under the first working condition, Ube1 = Ub1-Uc1, Uce1 = Uc1-Ue1, Ub2 represents the base voltage of the semiconductor device under the second working condition, Ue2 represents the emitter voltage of the semiconductor device under the second working condition, Ube2 = Ub2-Ue2, and Uon represents the on voltage of the semiconductor device.

[0017] The first working condition refers to that the second switch element is off and the first switch element is off, and the second working condition refers to that the second switch element is off and the first switch element is on.

[0018] Optionally, the output voltage of the first power supply is 12V±5%, the output voltage of the second power supply is 5V±5%, the resistance of the fifth resistor is 2kΩ±5%, the resistance of the first resistor is 20kΩ±5%, the resistance of the second resistor is 50kΩ±5%, the resistance of the third resistor is 50kΩ±5%, and the resistance of the fourth resistor is 10kΩ±5%.

[0019] Optionally, the load driving circuit works in cooperation with a judgment method, and the judgment method comprises the following steps: judging which one of 0V, 3V and 5V the voltage of the feedback output end is closer to, to obtain a voltage proximity value; if the voltage proximity value is 3V, judging that the first switch element is off and the second switch element is off; if the voltage proximity value is 5V, judging that the first switch element is on and the second switch element is off; and if the voltage proximity value is 0V, judging that the first switch element is off and the second switch element is on.

[0020] Compared to the prior art, the present invention provides a load drive circuit for driving a load, wherein the positive power supply of the load is connected to a first power supply. The load drive circuit includes a first switching element and a second switching element. The first connection end of the first switching element is grounded, the second connection end of the first switching element is connected to the first connection end of the second switching element, and the second connection end of the second switching element is connected to the negative power supply of the load. Redundant switching elements improve system reliability, and a specific connection relationship is designed to facilitate operation with a specific detection module. A single port is used to simultaneously feedback the operating status of two switching elements, solving the problem of insufficient control reliability of important loads in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0022] Figure 1 1 is a circuit connection diagram of a load driving circuit according to an embodiment of the present invention;

[0023] Figure 2 FIG. 1 is a diagram showing output characteristics of a semiconductor device according to an embodiment of the present invention.

[0024] In the attached figure:

[0025] 1-Monitoring module; 2-MCU; 3-Detection module; 4-Load. DETAILED DESCRIPTION

[0026] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.

[0027] As used in the present invention, the singular forms "a", "an", and "the" include plural referents, the term "or" is generally used to include "and / or", the term "several" is generally used to include "at least one", and the term "at least two" is generally used to include "two or more". In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to two corresponding parts, which not only include endpoints, and the terms "mounted", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be a communication between two elements or an interaction relationship between two elements. In addition, as used in the present invention, "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements may be direct or indirect through an intermediate element. It should not be understood as indicating or implying a spatial positional relationship between the two elements. That is, one element can be in any orientation, such as inside, outside, above, below, or to one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The core idea of ​​the present invention is to provide a load driving circuit to solve the problem of insufficient control reliability of important loads existing in the prior art.

[0029] The following description is given with reference to the accompanying drawings.

[0030] like Figure 1 As shown, this embodiment provides a load driving circuit, which is used to drive a load 4. The load 4 can be a main relay in a car, or other important loads.

[0031] The positive power supply of the load 4 is connected to the first power supply BATTERY. The load driving circuit includes a first switching element S1 and a second switching element S2. The first connection end of the first switching element S1 is grounded, the second connection end of the first switching element S1 is connected to the first connection end of the second switching element S2, and the second connection end of the second switching element S2 is connected to the negative power supply of the load. The first switching element S1 and the second switching element S2 can be transistors, MOS transistors, low-side transistors, logic devices, relays, and other components that can function as switches.

[0032] The first switch element S1 is used to turn on or off in response to a control signal from a controller (e.g., a control signal output by MCU2); the second switch element S2 is used to turn on or off in response to a control signal from the monitoring module 1; only when it is determined that the controller is in a safe state, the monitoring module 1 outputs a control signal to drive the second switch element to turn on. The specific logic of the monitoring module 1 can be set according to actual needs, and the conditions for judging whether the controller is in a safe state can also be set according to actual needs, which will not be described in detail here. The monitoring module 1 may be subordinate to or not subordinate to the controller. In one embodiment, the monitoring module 1 is a watchdog. When MCU2 is working normally, it outputs a fixed-pattern signal to the monitoring module 1 to periodically reset the count value of the monitoring module 1. When MCU2 is abnormal, it no longer outputs a signal, and the count value of the monitoring module 1 is not reset. When the trigger condition is met, the monitoring module alarms and / or resets MCU2.

[0033] With such a configuration, the load 4 is controlled by two redundant switches, thereby greatly reducing the possibility that the power-on state of the load 4 cannot be interrupted. In addition, the second switching element S2 is controlled by the monitoring module, so that the on-off state of the second switching element S2 is not affected by the intervention of the control algorithm, and the situation that the power-on state of the load 4 cannot be interrupted due to errors in the control logic is prevented, thereby improving the control reliability of the load 4.

[0034] To further improve control reliability, the load drive circuit further includes a detection module 3 for providing feedback on the actual on / off status of the first switching element S1 and the second switching element S2. The format of the feedback signal from the detection module 3 is not limited. The actual on / off status of the first switching element S1 and the second switching element S2 is involved in the control algorithm and how it affects the logic of the control algorithm can be configured based on actual needs and will not be described in detail here.

[0035] In order to simplify the structure of the detection module 3 and reduce the number of output terminals, the detection module includes a semiconductor device T1 , and the working states of the semiconductor device T1 include a cut-off state, an amplification state, and a saturation state.

[0036] When the first switch element S1 and the second switch element S2 traverse all combinations of on-off states, the operating state of the semiconductor device T1 traverses the off state, the amplified state, and the saturated state. The above statement means that there are four possible on-off state combinations of the first switch element S1 and the second switch element S2: (on, on), (on, off), (off, on), and (off, off), and these four possibilities correspond to three operating states, and all three operating states appear at least once. For example, in one embodiment, when the first switch element S1 is off and the second switch element S2 is off, the operating state of the semiconductor device T1 is the amplified state; when the first switch element S1 is on and the second switch element S2 is off, the operating state of the semiconductor device T1 is the off state; when the first switch element S1 is off and the second switch element S2 is on, the operating state of the semiconductor device is the saturated state. When the first switch element S1 is on and the second switch element S2 is on, the operating state of the semiconductor device can be any.

[0037] The detection module 3 only includes one feedback output terminal for feeding back the actual on / off status of the first switching element and the second switching element. The signal of the feedback output terminal (ie, Figure 1 VOUT in ) is generated based on the semiconductor device T1.

[0038] With such configuration, a single component can generate a variety of distinguishable output signals, thereby simplifying the structure, reducing the number of output terminals of the detection module 3, and lowering the manufacturing and layout costs.

[0039] In different embodiments, the semiconductor device T1 may be one of a transistor, a MOS tube, a thyristor and an IGBT.

[0040] exist Figure 1 In the illustrated embodiment, the semiconductor device T1 is an NPN transistor, and the collector of the semiconductor device T1 is configured as the feedback output terminal.

[0041] Figure 2It is the output characteristic curve of the transistor. As can be seen from the figure, when Ube (i.e. be pole voltage) <Uon(即开启电压)时,晶体管处于截止区,发射端电流Ic非常小,约几十微安;当Ube> When Uon and Uce (i.e., ce-pole voltage)>Ube, the transistor is in the amplification region and can be regarded as a current source outputting a constant current. The output current Ic=βIb (β is the current amplification factor of the transistor, which is an inherent parameter of the transistor); when Ube>Uon and Uce <Ube时,晶体管处于饱和区,晶体管可看作一个阻值为Ron的固定电阻(Ron为晶体管饱和电阻,为晶体管固有参数)。

[0042] Figure 2 The ic in it represents the collector current, Uce represents the ce electrode voltage, and I B ~I B4 Represents different typical current values. There will be specific values ​​in the specific curve diagram. Figure 2 The values ​​are not specified for illustration only. Δic and Δib are given by I B ~I B4 The interval between ic and ib is determined by the curve, and the specific value will be shown in the specific curve. Figure 2 It is only for reference, so the value is not indicated.

[0043] By utilizing the above features and combining them with corresponding resistors, the technical effect of different switching state combinations corresponding to different working states can be achieved.

[0044] Specifically, the detection module 3 further includes a first resistor R1 , a second resistor R2 , a third resistor R3 , a fourth resistor R4 and a fifth resistor Rd.

[0045] Among them, the first end of the first resistor R1 is used for grounding; the first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the first end of the fifth resistor R5; the second end of the fifth resistor R5 is used to connect to the second power supply VDD, and the first end of the fifth resistor R5 is also connected to the collector of the semiconductor device T1; the first end of the third resistor R3 is connected to the first end of the second resistor R2, and the second end of the third resistor R3 is connected to the base of the semiconductor device T1; the first end of the fourth resistor R4 is connected to the first end of the second resistor R2, and the second end of the fourth resistor R4 is connected to the second connection end of the first switching element S1.

[0046] The relevant electrical parameters can be determined as follows: Ube1 = VDD*R1 / (R1+R2+Rd), Ib = (Ub1-Ubeq) / R3, Ic = βIb, (VDD-Uce1) / Rd = (Uc1-Ub1) / R2+Ic, Ube1>Uon, Uce1 <Ube1,Ube2=VDD*(R4 / / R1) / (R4 / / R1+R2+Rd),Ube2<Uon,VBATTERY> VDD.

[0047] Wherein, the “ / / ” symbol represents the resistance of two resistors connected in parallel. VBATTERY represents the voltage of the first power supply, VDD represents the voltage of the second power supply, R1 represents the resistance of the first resistor, R2 represents the resistance of the second resistor, R3 represents the resistance of the third resistor, R4 represents the resistance of the fourth resistor, Rd represents the resistance of the fifth resistor, Ubeq represents the base voltage drop of the semiconductor device, β represents the amplification factor of the semiconductor device, Ub1 represents the base voltage of the semiconductor device under the first operating condition, Uc1 represents the collector voltage of the semiconductor device under the first operating condition, Ue1 represents the emitter voltage of the semiconductor device under the first operating condition, Ube1 = Ub1 - Uc1, Uce1 = Uc1 - Ue1, Ub2 represents the base voltage of the semiconductor device under the second operating condition, Ue2 represents the emitter voltage of the semiconductor device under the second operating condition, Ube2 = Ub2 - Ue2, and Uon represents the turn-on voltage of the semiconductor device.

[0048] The first operating condition means that the second switching element is turned off and the first switching element is turned off; the second operating condition means that the second switching element is turned off and the first switching element is turned on.

[0049] The analysis is as follows. When S2 is disconnected and S1 is disconnected, according to Figure 1 The connection relationship shown is as follows: Ube1=VDD*R1 / (R1+R2+Rd), Ib=(Ub-Ubeq) / R3, Ic=βIb, (VDD-Uce1) / Rd=(Uc1-Ub1) / R2+Ic, Ube1>Uon, Uce1 <Ube1。于是,T1处于晶体管的放大区。例如,Rd≈2kΩ,R2≈50kΩ,R3≈50kΩ,R1≈20kΩ,此时计算可得,VOUT=Uce1≈3V。

[0050] When S2 is open and S1 is closed, according to Figure 1The connection relationship shown has the following relationship: Ube2 = VDD * (R4 / / R1) / (R4 / / R1 + R2 + Rd), Ube2 < Uon. Since R4 / / R1 < R1, Ube2 < Ube1, and by adjusting the resistance value of R4, Ube2 < Uon < Ube1 can be achieved, at this time, T1 is in the cutoff region of the transistor, and Ic is only tens of milliamperes, so VOUT = Uce2 ≈ VDD = 5V. Uce2 = Uc2 - Ue2, Uc2 represents the collector voltage of the semiconductor device in the second case.

[0051] When S2 is closed and S1 is disconnected, at this time, the be voltage Ube3 of T1 ≈ VBATTERY = 12V, and the ce voltage Uce3 is at most VDD (5V), so Ube3 > Uce3, T1 is in the saturation region of the transistor, and VOUT = Uce3 = Ic * Ron ≈ 0V.

[0052] One solution that satisfies the above conditions is as follows: the output voltage of the first power supply is 12V ± 5%, the output voltage of the second power supply is 5V ± 5%, the resistance value of the fifth resistor is 2kΩ ± 5%, the resistance value of the first resistor is 20kΩ ± 5%, the resistance value of the second resistor is 50kΩ ± 5%, the resistance value of the third resistor is 50kΩ ± 5%, and the resistance value of the fourth resistor is 10kΩ ± 5%. In other embodiments, other parameters can also be selected.

[0053] In summary, by means of a clever circuit structure and careful calculation, transistor T1 can be in different working modes when S1 and S2 are in different switching states, and then the states of S1 and S2 can be determined according to a value of VOUT.

[0054] That is, the load driving circuit works in cooperation with a determination method, and the determination method includes the following steps: S10 determines which of 0V, 3V and 5V the voltage of the feedback output end is closer to, to obtain a voltage proximity value; S20 if the voltage proximity value is 3V, it is determined that the first switching element is disconnected and the second switching element is disconnected; S30 if the voltage proximity value is 5V, it is determined that the first switching element is turned on and the second switching element is disconnected; S40 if the voltage proximity value is 0V, it is determined that the first switching element is disconnected and the second switching element is turned on.

[0055] Among them, S10 can be set according to actual needs. For example, when VOUT<0.5V, it is judged that the voltage is close to 0V; when VOUT>4.5V, it is judged that the voltage is close to 5V; when 2.5V <VOUT<3.5V时,判断所述电压接近值为3V,在其他情况下报错。上述的参数0.5、4.5、2.5和3.5可以根据实际需要进行修改设置。

[0056] In the above process, the situation where the first switching element is turned on and the second switching element is turned on is not judged, but whether the two switching elements are turned on at the same time can be judged based on the working condition of the load 4. Therefore, the control algorithm of the previous level can make a comprehensive judgment based on the working condition of the load 4 and the output result of the judgment method to distinguish the four working state combinations corresponding to the two switching elements.

[0057] Figure 1 The beneficial effects of the embodiment shown are as follows:

[0058] (1) A redundant switch is added to the important load circuit, and the switch is controlled by the monitoring signal of the entire system to ensure that the important load can be turned on only when the system is safe. At the same time, the redundant switch greatly reduces the failure rate of the control circuit and ensures the reliability of the product.

[0059] (2) Using only simple electronic components, the status of switches S1 and S2 is monitored in a very low-cost manner, further improving the reliability of the product.

[0060] In summary, this embodiment provides a load driving circuit. The load driving circuit is used to drive a load, wherein the positive power supply of the load is connected to a first power supply. The load driving circuit includes a first switching element and a second switching element. The first connection end of the first switching element is used for grounding, the second connection end of the first switching element is connected to the first connection end of the second switching element, and the second connection end of the second switching element is used for connecting to the negative power supply of the load. The redundant switching elements improve the reliability of the system, and a specific connection relationship is designed to facilitate cooperation with a specific detection module. The working status of two switching elements is fed back simultaneously using one port, thereby solving the problem of insufficient control reliability of important loads existing in the prior art.

[0061] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A load driving circuit, characterized in that: The load driving circuit is used to drive a load, the positive power supply of the load is connected to the first power supply, and the load driving circuit includes a first switching element and a second switching element, the first connection end of the first switching element is used to be grounded, the second connection end of the first switching element is connected to the first connection end of the second switching element, and the second connection end of the second switching element is used to be connected to the negative power supply of the load; The first switch element is used to turn on or off in response to a control signal from a controller; the second switch element is used to turn on or off in response to a control signal from a monitoring module; only when it is determined that the controller is in a safe state, the monitoring module outputs a control signal to drive the second switch element to turn on; The load driving circuit further includes a detection module; The detection module includes a semiconductor device; the detection module includes only one feedback output terminal for feeding back the actual disconnection status of the first switching element and the second switching element, and the signal of the feedback output terminal is generated based on the semiconductor device; The semiconductor device is an NPN transistor, and the collector of the semiconductor device is configured as the feedback output terminal; The detection module further includes a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor; wherein, The first end of the first resistor is connected to the ground; the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the first end of the fifth resistor; the second end of the fifth resistor is connected to the second power supply, and the first end of the fifth resistor is also connected to the collector of the semiconductor device; the first end of the third resistor is connected to the first end of the second resistor, and the second end of the third resistor is connected to the base of the semiconductor device; the first end of the fourth resistor is connected to the first end of the second resistor, and the second end of the fourth resistor is connected to the second connection end of the first switching element; The common connection point between the first switch element and the detection module is only the second end of the fourth resistor, and the common connection point between the second switch element and the detection module is only the second end of the fourth resistor; The following electrical parameters meet the following conditions: Ube1=VDD*R1 / (R1+R2+Rd), Ib=(Ub1-Ubeq) / R3, Ic=βIb, (VDD-Uce1) / Rd=(Uc1-Ub1) / R2+Ic, Ube1>Uon, Uce1 <Ube1,Ube2=VDD*(R4 / / R1) / (R4 / / R1+R2+Rd),Ube2<Uon,VBATTERY> VDD; Wherein, VBATTERY represents the voltage of the first power supply, VDD represents the voltage of the second power supply, R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, R3 represents the resistance value of the third resistor, R4 represents the resistance value of the fourth resistor, Rd represents the resistance value of the fifth resistor, Ubeq represents the base voltage drop of the semiconductor device, β represents the amplification factor of the semiconductor device, Ub1 represents the base voltage of the semiconductor device under the first operating condition, Uc1 represents the collector voltage of the semiconductor device under the first operating condition, Ue1 represents the emitter voltage of the semiconductor device under the first operating condition, Ube1=Ub1-Uc1, Uce1=Uc1-Ue1, Ub2 represents the base voltage of the semiconductor device under the second operating condition, Ue2 represents the emitter voltage of the semiconductor device under the second operating condition, Ube2=Ub2-Ue2, and Uon represents the turn-on voltage of the semiconductor device; The first operating condition refers to that the second switching element is turned off and the first switching element is turned off; the second operating condition refers to that the second switching element is turned off and the first switching element is turned on.

2. The load driving circuit according to claim 1, wherein: The working state of the semiconductor device includes a cut-off state, an amplified state and a saturated state; when the first switch element and the second switch element traverse all combinations of the open and close states, the working state of the semiconductor device traverses the cut-off state, the amplified state and the saturated state.

3. The load driving circuit according to claim 2, wherein: When the first switching element is turned off and the second switching element is turned off, the working state of the semiconductor device is an amplification state; when the first switching element is turned on and the second switching element is turned off, the working state of the semiconductor device is a cut-off state; when the first switching element is turned off and the second switching element is turned on, the working state of the semiconductor device is a saturation state.

4. The load driving circuit according to claim 1, wherein: The output voltage of the first power supply is 12V±5%, the output voltage of the second power supply is 5V±5%, the resistance of the fifth resistor is 2kΩ±5%, the resistance of the first resistor is 20kΩ±5%, the resistance of the second resistor is 50kΩ±5%, the resistance of the third resistor is 50kΩ±5%, and the resistance of the fourth resistor is 10kΩ±5%.

5. The load driving circuit according to claim 4, wherein: The load driving circuit works in conjunction with a determination method, the determination method comprising the following steps: Determine whether the voltage of the feedback output terminal is closer to 0V, 3V, or 5V, and obtain a voltage approximation value; If the voltage is close to 3V, it is determined that the first switch element is disconnected and the second switch element is disconnected; If the voltage is close to 5V, it is determined that the first switch element is turned on and the second switch element is turned off; If the voltage is close to 0V, it is determined that the first switch element is turned off and the second switch element is turned on.

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