An anti-reverse connection circuit and an anti-reverse connection device

Abstract

The present application provides an anti-reverse connection circuit and an anti-reverse connection device, which relate to the technical field of anti-reverse connection. The anti-reverse connection circuit includes a central control module, a voltage dividing component, a driving component, and a transistor. The voltage dividing component is used to be electrically connected to the positive input terminal and the reverse input terminal of a load power supply, and the voltage dividing component is also electrically connected to the input terminal of the central control module. The output terminal of the central control module, the driving component, and the transistor are electrically connected in sequence. The transistor is also electrically connected to the input terminal of the load power supply. The driving component is also used to be electrically connected to a driving power supply. The positive input terminal and the reverse input terminal of the load power supply are also used to be electrically connected to a load. The central control module is used to receive the current voltage collected by the voltage dividing component and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. The anti-reverse connection circuit and the anti-reverse connection device provided by the present application have the effects of low power consumption and being able to work normally even when the voltage value of the load power supply is low.

Description

Technical Field

[0001] This application relates to the technical field of anti-reverse connection, and in particular, to an anti-reverse connection circuit and an anti-reverse connection device. Background Art

[0002] When an electrical circuit or an electrical device is powered by direct current, since the positive and negative poles of the input power supply may be connected reversely, the electrical circuit or the electrical device may be damaged. Therefore, a corresponding anti-reverse connection circuit is generally required.

[0003] Currently, diodes or NMOS transistors are generally used to prevent reverse input of direct current power supply. However, the input power consumption of diodes is relatively large; when the power supply voltage is small, the NMOS transistor cannot conduct, and due to the large forward voltage drop of the body diode, the power consumption is relatively large, and even the NMOS transistor may be damaged.

[0004] In summary, the current anti-reverse connection circuit has the problem of high power consumption. Summary of the Invention

[0005] The purpose of this application is to provide an anti-reverse connection circuit and an anti-reverse connection device to solve the problem of relatively high power consumption existing in the anti-reverse connection circuit in the prior art.

[0006] To achieve the above purpose, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, an embodiment of this application provides an anti-reverse connection circuit. The anti-reverse connection circuit includes a central control module, a voltage dividing component, a driving component, and a transistor. The voltage dividing component is used to be electrically connected to the positive input terminal and the reverse input terminal of a load power supply, and the voltage dividing component is also electrically connected to the input terminal of the central control module. The output terminal of the central control module, the driving component, and the transistor are electrically connected in sequence. The transistor is also electrically connected to the input terminal of the load power supply. The driving component is also used to be electrically connected to a driving power supply. The positive input terminal and the reverse input terminal of the load power supply are also used to be electrically connected to a load. The central control module is used to receive the current voltage collected by the voltage dividing component and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. Wherein, when the load power supply is correctly connected and the current voltage is greater than the reference voltage, the central control module outputs the first signal; when the load power supply is reversely connected, the current voltage is less than the reference voltage, so that the central control module outputs the second signal; when the central control module outputs the first signal, the driving component is used to connect the transistor to the driving power supply and drive the transistor to be in a conducting state, so that the load power supply supplies power to the load; when the central control module outputs the second signal, the driving component is used to cut off the connection between the transistor and the driving power supply and drive the transistor to be in a cut-off state to prevent the reverse connection of the load power supply.

[0008] Optionally, the central control module is further configured to output a second signal when the load power supply is connected correctly and the current voltage is less than the reference voltage.

[0009] Optionally, the voltage dividing component is electrically connected to the positive input terminal of the central control module. The reverse connection prevention circuit further includes a hysteresis module. One end of the hysteresis module is electrically connected to the driving component and the output terminal of the central control module respectively, and the other end of the hysteresis module is electrically connected to the positive input terminal of the central control module and the voltage dividing component respectively. The hysteresis module is configured to feedback a partial voltage of the driving power supply to the voltage dividing component after the central control module outputs the first signal, so as to maintain the transistor in a conducting state within a target voltage range when the load voltage fluctuates, thereby avoiding frequent conduction and cut-off of the transistor.

[0010] Optionally, the hysteresis module includes a diode and a first resistor. The anode of the diode is electrically connected to the driving component and the output terminal of the central control module respectively, the cathode of the diode is electrically connected to one end of the first resistor, and the other end of the first resistor is electrically connected to the positive input terminal of the central control module and the voltage dividing component respectively.

[0011] Optionally, the voltage dividing component includes a second resistor and a third resistor. One end of the second resistor is electrically connected to the positive input terminal of the load power supply, the other end of the second resistor is electrically connected to one end of the third resistor and the positive input terminal of the central control module respectively, and the other end of the third resistor is electrically connected to the reverse input terminal of the load power supply.

[0012] Optionally, the voltage dividing component is electrically connected to the positive input terminal of the central control module. The reverse connection prevention circuit further includes a reference voltage module. The reference voltage module is electrically connected to the driving power supply and the reverse input terminal of the central control module respectively, so as to use the voltage output by the reference voltage module as the reference voltage of the central control module.

[0013] Optionally, the reference voltage module includes a fourth resistor and a voltage stabilizing diode. One end of the fourth resistor is used to be electrically connected to the driving power supply, the other end of the fourth resistor is electrically connected to the reverse input terminal of the central control module and the negative electrode of the voltage stabilizing diode respectively, and the positive electrode of the voltage stabilizing diode is grounded.

[0014] Optionally, the driving component includes an NPN transistor and a PNP transistor. The bases of the NPN transistor and the PNP transistor are both electrically connected to the output end of the central control module. The collector of the NPN transistor is electrically connected to the driving power supply. The emitter of the NPN transistor is respectively electrically connected to the emitter of the PNP transistor and the first end of the transistor. The collector of the PNP transistor is electrically connected to the second end of the transistor.

[0015] Optionally, the central control module includes a comparator and an operational amplifier.

[0016] On the other hand, an embodiment of the present application further provides an anti-reverse connection device. The anti-reverse connection device includes a load and the above anti-reverse connection circuit. The anti-reverse connection circuit is electrically connected to the input end of the load.

[0017] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0018] The embodiments of the present application provide an anti-reverse connection circuit and an anti-reverse connection device. The anti-reverse connection circuit includes a central control module, a voltage dividing component, a driving component, and a transistor. The voltage dividing component is used to be electrically connected to the positive input end and the negative input end of a load power supply, and the voltage dividing component is also electrically connected to the input end of the central control module. The output end of the central control module, the driving component, and the transistor are sequentially electrically connected. The transistor is also electrically connected to the input end of the load power supply. The driving component is also used to be electrically connected to a driving power supply. The positive input end and the negative input end of the load power supply are also used to be electrically connected to a load. The central control module is used to receive the current voltage collected by the voltage dividing component and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. Among them, when the load power supply is correctly connected, the current voltage is greater than the reference voltage, so that the central control module outputs a first signal. When the load power supply is reversely connected, the current voltage is less than the reference voltage, so that the central control module outputs a second signal. When the central control module outputs the first signal, the driving component is used to connect the transistor to the driving power supply and drive the transistor to be in a conducting state, so that the power supply supplies power to the load. When the central control module outputs the second signal, the driving component is used to cut off the connection between the transistor and the driving power supply and drive the transistor to be in a cut-off state, so as to cut off the power supply from supplying power to the load, so as to achieve the function of preventing reverse connection. Since the present application adopts the combination of the central control module and the transistor to achieve the effect of preventing reverse connection, on the one hand, it can achieve the effect of reducing power consumption. On the other hand, by using the comparison method to achieve the effect of outputting signals, the reference voltage can be set to be relatively low, so that even when the input power supply voltage value is small, the transistor can be completely turned on.

[0019] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given below in conjunction with the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0021] Figure 1 It is the circuit diagram of the first reverse connection prevention circuit in the prior art.

[0022] Figure 2 It is the circuit diagram of the second reverse connection prevention circuit in the prior art.

[0023] Figure 3 It is the module schematic diagram of the reverse connection prevention circuit in the embodiments of the present application.

[0024] Figure 4 It is the circuit diagram of the reverse connection prevention circuit in the embodiments of the present application.

[0025] In the figure: 100 - reverse connection prevention circuit; 110 - central control module; 120 - voltage dividing component; 130 - driving component; 140 - transistor; 150 - hysteresis module; 160 - reference voltage module; R1 - first resistor; R2 - second resistor; R3 - third resistor; R4 - fourth resistor; D1 - diode; Z1 - zener diode; C1 - filter capacitor; Q1 - NPN transistor; Q2 - PNP transistor. Specific embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0029] It should be noted that, in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0030] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is customarily placed during use. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present application.

[0031] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "arranged", "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 directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] The following will describe in detail some embodiments of the present application with reference to the drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] As described in the Beijing technology, currently, when directly supplying power to an electrical circuit or an electrical device, since the electrical circuit or the electrical device may be damaged if the positive and negative poles of the input power supply are connected reversely, generally a corresponding reverse connection prevention circuit needs to be provided.

[0034] Generally, the current reverse connection prevention circuit includes the following two methods:

[0035] First, the method of using a diode is adopted to achieve the effect of reverse connection prevention. Please refer to Figure 1 , a diode D1 is connected to the positive or negative pole of the DC input. When the diode D1 is connected to the positive pole of the DC input, the positive pole of the diode D1 is connected to the power supply, and the negative pole of the diode D1 is connected to the load. When the positive pole of the DC input is connected to VIN+ (input positive pole) and the negative pole of the DC input is connected to VIN- (input negative pole), the current flows through the diode D1 to supply power to the load. When the positive and negative poles of the DC input are reversed, that is, the negative pole of the DC input is connected to VIN+ and the positive pole of the DC input is connected to VIN-, the diode D1 is cut off due to the unidirectional conduction characteristic, that is, the current cannot flow reversely through the diode D1, realizing the input reverse connection protection function. As an implementation method, the load described in this application can be an electrical circuit or an electrical device.

[0036] Among them, when using the diode D1 to achieve the reverse connection prevention function, when the supply input current is large, the diode D1 will generate a large power loss, reducing the power supply efficiency. For example, assuming that the supply input current is 10A and the forward voltage drop of the diode D1 is set to 0.5V, the loss on the diode is 10×0.5 = 5 (W). A large power loss is generated on the diode, reducing the power supply efficiency.

[0037] Second, the method of using an NMOS (N-Metal-Oxide-Semiconductor) tube is adopted to achieve the effect of reverse connection prevention. Please refer to Figure 2 , as an implementation method, the NMOS tube Q1 is connected in series in the negative circuit of the DC power supply. The drain (D) of the NMOS tube is connected to the negative pole of the power supply input, the source (S) of the NMOS tube Q1 is connected to the negative pole of the load, and the gate (G) of the NMOS tube Q1 is connected to the positive pole of the power supply input through the resistor R1 and is also connected to the source of the NMOS tube Q1 through the resistor R2. For the convenience of explanation, the input voltage is set to 24V, and the resistance values of R1 and R2 are set to 20kR. Of course, when other voltage values are input, the resistance values of the resistors R1 and R2 can be determined according to actual needs.

[0038] When the positive pole of the input power supply is connected to VIN+ and the negative pole of the power supply is connected to VIN-. Ignoring the voltage drop when the current flows through the body diode of Q1, the potential difference between points A and C is 24V. Since R1 = R2, the potential difference across R2 is 12V, that is, the voltage between the gate (G) and the source (S) of Q1 is 12V. Assume that the model of Q1 is BSC007N04LS6, and its data sheet is shown in Table 1.

[0039] 3 Electrical characteristics

[0040] at T j , = 25 °C, unless otherwise specified

[0041] Table 4 Static characteristics

[0042]

[0043] Table 1

[0044] As can be seen from Table 1, when Q1 is conducting, the corresponding GS voltage threshold is 2.3 V, and the typical value of R DS (on) is 0.62 mR. Since 12 V > 2.3 V, Q1 is conducting at this time, and the current flows into the source (S) of Q1 and out of the drain (D), returning to VIN-. It can be understood that since Q1 is turned on at this time, the current will not flow through the parasitic diode of Q1. For the sake of convenience of explanation, assuming an input current of 10 A, the typical value of the conduction loss on Q1 is 10×10×0.62 = 0.062 (W), which is much smaller than the power loss of 5 W when using a diode for reverse protection.

[0045] When the DC input is reversed, that is, the negative pole of the DC input is connected to VIN+ and the positive pole of the DC input is connected to VIN-, the parasitic diode of Q1 is cut off, and Q1 remains off because there is no positive voltage greater than 2.3 V between the G and S poles. Therefore, the current will not flow from the drain (D) of Q1 to the source (S), that is, the current cannot flow from point E to point C, so the input reverse connection protection function can be realized.

[0046] However, when the supply voltage is low, for example, the supply voltage is 1 V. Since 1 V is less than the conduction threshold voltage of the NMOS transistor (such as 2.3 V), Q1 is not conducting. The current will all flow through the parasitic diode of Q1, and the current can also flow from the S pole of Q1 to the D pole. However, it can be seen from the data sheet that the typical value of the voltage drop of the parasitic diode of this NMOS transistor is 0.78 V. Assuming a current of 10 A flowing through, the loss of the parasitic diode is 0.78×10 = 7.8 (W). At this time, the power loss of the NMOS is large, which may cause damage to the NMOS, reduce the power efficiency of the system, waste electric energy, increase the temperature rise of the circuit, and reduce the reliability and life of the circuit.

[0047] In view of this, in order to reduce the power consumption of the reverse connection protection circuit and prevent the problem of damage to the NMOS transistor caused by low-voltage DC input, the present application provides a reverse connection protection circuit. By setting a modular transistor in the reverse connection protection circuit, the conduction or cut-off of the transistor is controlled by using a voltage comparison method, so as to reduce the power consumption while preventing damage to the transistor even when the DC input voltage is small, and at the same time realizing the input reverse connection protection function.

[0048] An exemplary description of the reverse connection prevention circuit provided in this application is as follows:

[0049] As an alternative implementation, please refer to Figure 3 , the reverse connection prevention circuit 100 includes a central control module 110, a voltage dividing component 120, a driving component 130, and a transistor 140. The voltage dividing component 120 is used to be electrically connected to the positive input terminal and the reverse input terminal of a load power supply, and the voltage dividing component 120 is also electrically connected to the input terminal of the central control module 110. The output terminal of the central control module 110, the driving component 130, and the transistor 140 are electrically connected in sequence. The transistor 140 is also electrically connected to the input terminal of the load power supply. The driving component 130 is also electrically connected to a driving power supply. The positive input terminal and the reverse input terminal of the load power supply are also used to be electrically connected to a load.

[0050] Among them, the central control module 110 is used to receive the current voltage collected by the voltage dividing component 120, and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. Among them, when the load power supply is correctly connected and the current voltage is greater than the reference voltage, the central control module 110 outputs a first signal; when the load power supply is reversely connected, the current voltage is less than the reference voltage, so that the central control module 110 outputs a second signal. When the central control module 110 outputs the first signal, the driving component 130 is used to connect the transistor 140 to the driving power supply and drive the transistor 140 to be in a conducting state, so that the load power supply can supply power to the load with high efficiency; when the central control module 110 outputs the second signal, the driving component 130 is used to cut off the connection between the transistor 140 and the driving power supply and drive the transistor 140 to be in a cut-off state, so as to cut off the power supply of the load power supply to the load and realize the input reverse connection protection function.

[0051] At the same time, as an implementation, the central control module is also used to output a second signal when the load power supply is correctly connected and the current voltage is less than the reference voltage. In other words, even when the load power supply is correctly connected, if the voltage value of the load power supply is small, the driving component 130 will also drive the transistor 140 to be in a cut-off state, thereby ensuring that the load power supply cannot supply low voltage power to the load and protecting the load.

[0052] Since this application uses the transistor 140 to implement the reverse connection prevention function, it can achieve the effect of low power consumption. Moreover, by using the central control module 110 to compare voltages to control the conduction and cut-off of the transistor 140, the reference voltage can be set very low. Therefore, even when the input voltage of the load power supply is low, it can still achieve the conduction of the transistor 140, and thus there will be no situation of using the body diode D1 of the transistor 140 to transmit current, reducing power consumption while protecting the transistor 140.

[0053] It should be noted that the transistor 140 described in this application can be a bipolar transistor or a MOS transistor. This application does not make any limitations in this regard. At the same time, when a MOS transistor is used, it can be an NMOS transistor or a PMOS transistor, which can be set according to actual needs.

[0054] It should also be noted that the central control module 110 described in this application can be a comparator or an operational amplifier. Among them, the comparator or operational amplifier can be of any model. For example, it can be an operational amplifier or comparator with an internal reference voltage, or an operational amplifier or comparator with an external reference voltage. This application does not make any limitations.

[0055] For the convenience of description, this application will be described with an operational amplifier with an external reference voltage. On this basis, the voltage dividing component 120 is electrically connected to the positive input terminal of the central control module 110. The reverse connection prevention circuit 100 further includes a reference voltage module 160. The reference voltage module 160 is respectively electrically connected to the driving power supply and the inverting input terminal of the central control module 110. Among them, the voltage output by the reference voltage module 160 is the reference voltage of the central control module 110.

[0056] Optionally, the reference voltage module 160 includes a fourth resistor R4 and a voltage stabilizing diode Z1. One end of the fourth resistor R4 is used to be electrically connected to the driving power supply. The other end of the fourth resistor R4 is respectively electrically connected to the inverting input terminal of the central control module 110 and the negative electrode of the voltage stabilizing diode Z1. The positive electrode of the voltage stabilizing diode Z1 is grounded. By setting the voltage stabilizing diode Z1, the voltage at the voltage stabilizing diode can be maintained at a stable voltage value. For example, the voltage can be stabilized at 2V, then the voltage at the inverting input terminal of the central control module 110 is 2V. Thus, the preset reference voltage is also 2V.

[0057] Of course, in order to set the reference voltage according to actual needs, different models of voltage stabilizing diodes Z1 can be used to adjust the reference voltage. For example, in an application scenario where the voltage of the load power supply is generally not less than 1V, a voltage stabilizing diode Z1 with a voltage stabilizing ability of 1V is selected, thus avoiding the situation where the transistor 140 is not turned on when the voltage of the load power supply is low.

[0058] And, as another optional implementation manner, this application can replace the voltage stabilizing diode with a resistor form. By setting the resistance values of this resistor and the fourth resistor R4, the reference voltage of the central control module 110 can be determined in a voltage dividing manner.

[0059] It can be understood that when an operational amplifier or comparator with an internal reference voltage is selected, the above reference voltage module 160 can be cancelled.

[0060] Please refer to Figure 4, as an implementation, the voltage dividing component 120 includes a second resistor R2 and a third resistor R3. One end of the second resistor R2 is electrically connected to the positive input terminal of the load power supply, and the other end of the second resistor R2 is respectively electrically connected to one end of the third resistor R3 and the positive input terminal of the central control module 110. The other end of the third resistor R3 is electrically connected to the negative input terminal of the load power supply. It can be understood that through the voltage dividing effect of the voltage dividing resistors, the positive input terminal of the central control module 110 can receive the real-time voltage.

[0061] The central control module 110 compares the real-time voltage received at the positive input terminal with the reference voltage received at the negative input terminal, and outputs a first signal or a second signal according to the comparison result. For example, the first signal is a high-level signal, and the second signal is a low-level signal. When the real-time voltage is greater than the reference voltage, the central control module 110 outputs a high-level signal. When the real-time voltage is less than the reference voltage, the central control module 110 outputs a low-level signal.

[0062] Meanwhile, as an implementation, the driving component includes an NPN transistor Q1 and a PNP transistor Q2. The bases of the NPN transistor Q1 and the PNP transistor Q2 are both electrically connected to the output terminal of the central control module 110. The collector of the NPN transistor Q1 is electrically connected to the driving power supply. The emitter of the NPN transistor Q1 is respectively electrically connected to the emitter of the PNP transistor Q2 and the first end of the transistor 140. The collector of the PNP transistor Q2 is electrically connected to the second end of the transistor 140. On this basis, the transistor 140 can be an NMOS transistor, and the other negative input terminal of the load power supply is electrically connected. When the central control module 110 outputs a high-level signal, the NPN transistor Q1 conducts, and the PNP transistor Q2 cuts off, so that the driving power supply supplies power to the gate of the transistor 140, and the transistor 140 is in a conducting state, so that the load power supply can normally supply power to the load.

[0063] When the load power supply is reversely connected, at this time the central control module 110 outputs a low-potential signal, the NPN transistor Q1 cuts off, and the P-type three-stage tube conducts. At this time, the transistor 140 is in a cut-off state, so the power supply of the load power supply to the load is cut off, realizing the input reverse connection protection function.

[0064] It should be noted that when the transistor 140 is a PMOS transistor, its anti-reverse connection logic is opposite. That is, the PMOS transistor can be set at the positive input terminal of the load power supply. At the same time, the positive input terminal of the central control module 110 is used to obtain the reference voltage, and the negative input terminal is used to obtain the real-time voltage through the voltage dividing component 120.

[0065] Meanwhile, in order to achieve the filtering effect on the drive power supply, the reverse connection prevention circuit 100 further includes a filtering capacitor C1. One end of the filtering capacitor C1 is electrically connected to the drive power supply, and the other end is grounded. As an implementation manner, the capacitance value of the filtering capacitor C1 can be 1 uF to 10 uF.

[0066] The following takes the central control module 110 as an operational amplifier powered by a 12V drive power supply, and the transistor 140 as an NMOS transistor as an example for illustration: Assume that the load power supply between VIN+ and VIN- is a 3.3V DC voltage.

[0067] When the input positive and negative poles are not reversely connected, since the operational amplifier is powered by 12V DC power supply, the voltage of point F with respect to point C (ground) in the figure is 12V, and the current flows through the fourth resistor R4 and the voltage stabilizing diode Z1. Assuming that the voltage stabilizing diode Z1 is a 2V voltage stabilizing diode, the voltage of point I with respect to point C is 2V, that is, the voltage at the inverting input terminal of the operational amplifier is 2V, and this voltage is the reference voltage.

[0068] Assume that the NMOS transistor is initially in the cut-off state. Set the resistance value of the second resistor R2 to 2 kΩ and the resistance value of the third resistor R3 to 20 kΩ. Then the input voltage is applied across the second resistor R2, the third resistor R3, and the NMOS transistor, and the current flows through the second resistor R2, the third resistor R3, and the body diode D1 of the NMOS transistor in sequence. Assume that the load is initially in the non-operating state. The current flowing through the body diode D1 of the NMOS transistor body is the current flowing through the second resistor R2 and the third resistor R3. This current value is at the microampere level. Therefore, the voltage difference V between the source (S pole) and the drain (D pole) of the NMOS transistor SD is very small. Assume V SD = 0V, that is, point C and point E are at the same potential. Since the input voltage is 3.3V, the resistance value of the second resistor R2 is 2 kΩ, and the resistance value of the third resistor R3 is 20 kΩ, and the second resistor R2 and the third resistor R3 are in series, the voltage across the third resistor R3 is 3V, that is, the voltage of point B with respect to point C is 3V, and the real-time voltage at the non-inverting input terminal of the operational amplifier is 3V.

[0069] At this time, the voltage at the non-inverting input terminal of the operational amplifier is greater than the voltage at the inverting input terminal. Therefore, the operational amplifier outputs a high level, that is, point J is at a high level, the NPN transistor Q1 conducts, and the PNP transistor Q2 cuts off. Assume that the operational amplifier U1 is a rail-to-rail operational amplifier, then the voltage of point J with respect to ground is 12V. After the NPN transistor Q1 conducts, the current flows into from the collector of the NPN transistor Q1 and flows out from the emitter of the NPN transistor Q1 to the gate of the NMOS transistor. The voltage between the gate and the source of the NMOS transistor changes from a low level to a high level, and the NMOS transistor turns on. After the NMOS transistor turns on, the equivalent resistance between its drain and source is a small resistor, and the resistance value of this resistor is the R of this NMOS DS。Set the NMOS transistor model as BSC007N04LS6. From the above data sheet, it is known that after turning on, the typical R DS value of the NMOS transistor is 0.62 mΩ. Therefore, when the supply input current is 10 A, the loss on the NMOS transistor is 10×10×0.62 = 0.062 (W), and the power loss is very low, which is beneficial to improving the power efficiency of the circuit.

[0070] When the load power supply is reversely connected, that is, the positive pole of 3.3 V is connected to VIN-, and the negative pole of 3.3 V is connected to VIN+. At this time, it can be discussed in two cases:

[0071] First, the NMOS transistor is in the off state. There is no positive voltage difference between point C and point A, and no current flows through the third resistor R3 and the second resistor R2. Points C and B are at the same potential, that is, there is no voltage across the third resistor R3. Therefore, the voltage of the non-inverting input terminal of the operational amplifier with respect to the ground (point C) is 0 V. At this time, the voltage of the inverting input terminal of the operational amplifier with respect to the ground is 2 V. The voltage of the inverting input terminal is greater than the voltage of the non-inverting input terminal, so the operational amplifier outputs a low voltage, the voltage at point J is low, the NPN transistor Q1 is cut off, and the PNP transistor Q2 is turned on. That is, the emitter and collector of the PNP transistor Q2 are in a low-impedance state, and the gate and source of the NMOS transistor are turned on and short-circuited. Therefore, the voltage difference between the gate and source of the NMOS transistor is 0 V, and the NMOS transistor remains off. The body diode D1 of the NMOS transistor has its anode connected to the S pole and its cathode connected to the D pole, realizing the function of reverse connection prevention.

[0072] Second, the NMOS transistor is in the on state. At this time, the input reverse current will flow through the NMOS transistor, the third resistor R3, and the second resistor R2 in sequence. The potential of point B is lower than the potential of point C, that is, the voltage of the non-inverting input terminal of the operational amplifier is a negative voltage, and the inverting input voltage is 2 V. Therefore, once the operational amplifier detects that the voltage of the non-inverting input terminal is lower than the voltage of the inverting input terminal, it will immediately output a low level, turn off the NPN transistor Q1, and turn on the PNP transistor Q2, thereby quickly turning off the NMOS transistor. The circuit response time is in the microsecond level. In other words, if the input DC is reversely connected instantaneously during the operation of the circuit, the reverse connection prevention circuit 100 provided by the present application can also quickly and effectively protect the load and prevent the load from being damaged due to reverse connection.

[0073] Of course, the above is only an example. In actual applications, the parameters of the second resistor R2, the third resistor R3, the fourth resistor R4, and the zener diode Z1 can also be selected according to actual needs. At the same time, the supply voltage of the drive power supply is not limited to 12 V, and it can also be any voltage above 5 V, which can ensure the effective conduction of the transistor 140.

[0074] In practical applications, the load power supply may fluctuate, which may cause the transistor 140 to turn off frequently, resulting in oscillations and unstable circuit operation. In view of this, the reverse connection prevention circuit 100 provided in this application further includes a hysteresis module 150. One end of the hysteresis module 150 is electrically connected to the output ends of the driving component 130 and the central control module 110 respectively, and the other end of the hysteresis module 150 is electrically connected to the positive input end of the central control module 110 and the voltage dividing component 120 respectively; the hysteresis module 150 is used to feedback a part of the voltage of the driving power supply to the voltage dividing component 120 after the central control module 110 outputs a first signal, so as to keep the transistor 140 in the on state within a target voltage range when the load voltage fluctuates, thereby avoiding the situation that the transistor switches frequently and causes resonance of the power supply line.

[0075] As an implementation manner, the hysteresis module 150 includes a diode D1 and a first resistor R1. The anode of the diode D1 is electrically connected to the output ends of the driving component 130 and the central control module 110 respectively, the cathode of the diode D1 is electrically connected to one end of the first resistor R1, and the other end of the first resistor R1 is electrically connected to the positive input end of the central control module 110 and the voltage dividing component 120 respectively.

[0076] By setting the hysteresis module 150, a part of the voltage of the driving power supply can be feedback to the voltage dividing component 120, so that the real-time signal at the positive-phase input end of the central control module 110 increases. Even if the voltage of the load power supply fluctuates within a certain range, the transistor 140 can be kept in a stable on state, thereby protecting the transistor 140.

[0077] Among them, the diode D1 can use the one-way conduction characteristic to prevent current from flowing through the first resistor R1, thereby increasing the level of point J and even possibly mis-turning on Q2. In other words, the diode D1 can prevent the transistor 140 from being mis-conducted and ensure the normal operation of the circuit. At the same time, the diode D1 can also prevent current from flowing from point B through the first resistor R1 to point J when the operational amplifier outputs a low level, reducing the level of point B and reducing the accuracy of detecting the input voltage at the non-inverting input end of the operational amplifier. In other words, the diode D1 can also improve the accuracy of detecting the input voltage of the operational amplifier and improve the voltage accuracy of the protection circuit.

[0078] The working principle of the hysteresis module 150 provided in this application is exemplarily described below:

[0079] During the rising process of the input voltage of the load power supply, once the voltage difference between points B and C exceeds 2V, that is, the voltage at the non-inverting input terminal of the operational amplifier exceeds the voltage at the inverting input terminal, the operational amplifier will output a high level, causing the voltage at point J to change from low level to 12V, and current will flow through diode D1, the first resistor R1, and the third resistor R3. Assuming the voltage drop of diode D1 is 0V, setting the resistance value of the first resistor R1 to 464kΩ and the resistance value of the third resistor R3 to 20kΩ, the voltage divided by the third resistor R3 from the 12V voltage output by the operational amplifier is 0.5V, that is, the hysteresis voltage is 0.5V. For the 3.3V input voltage, the voltage divided by the second resistor R2 across the third resistor R3 is 3V. Therefore, at this time, the voltage across the third resistor R3 is 3.5V. When the input voltage drops to 1.65V, the voltage divided by the input voltage across the third resistor R3 is 1.5V. Adding the 0.5V hysteresis voltage, the voltage across the third resistor R3 is 2V, that is, the non-inverting input voltage of the operational amplifier is 2V. At this time, the non-inverting input voltage and the inverting input voltage of the operational amplifier are the same, and the operational amplifier operates in a critical state. Once the input voltage is lower than 1.65V, the non-inverting input voltage of the operational amplifier is less than the inverting input voltage, the operational amplifier outputs a low level, and the 0.5V hysteresis voltage superimposed on the third resistor R3 disappears. The non-inverting input voltage of the operational amplifier is further less than the inverting input voltage, and the NPN transistor Q1 is cut off while the PNP transistor Q2 is turned on, and the positive voltage V between the gate and the source of the transistor 140 GS discharges through the PNP transistor Q2, and the transistor 140 automatically turns off. That is, theoretically, if the input voltage drops, the transistor 140 can stably remain turned on between 3.3V and 1.65V. Once the input voltage drops below 1.65V, the transistor 140 can quickly turn off. Therefore, by setting the hysteresis module 150, even when the input voltage of the load power supply fluctuates, the transistor 140 will not switch frequently or oscillate, enabling the circuit to work stably and reliably.

[0080] Of course, when it is necessary to set the hysteresis voltage within other ranges, the resistance value of the first resistor R1 can be changed, and the present application does not make any limitations on this.

[0081] Based on the above embodiments, the present application also provides an anti-reverse connection device, which includes a load and an anti-reverse connection circuit 100, and the anti-reverse connection circuit 100 is electrically connected to the input terminal of the load.

[0082] In summary, the embodiments of the present application provide an anti-reverse connection circuit and an anti-reverse connection device. The anti-reverse connection circuit includes a central control module, a voltage dividing component, a driving component, and a transistor. The voltage dividing component is used to be electrically connected to the positive input terminal and the negative input terminal of a load power supply, and the voltage dividing component is also electrically connected to the input terminal of the central control module. The output terminal of the central control module, the driving component, and the transistor are electrically connected in sequence. The transistor is also electrically connected to the input terminal of the load power supply. The driving component is also used to be electrically connected to a driving power supply. The positive input terminal and the negative input terminal of the load power supply are also used to be electrically connected to a load. The central control module is used to receive the current voltage collected by the voltage dividing component and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. Among them, when the load power supply is correctly connected, the current voltage is greater than the reference voltage, so that the central control module outputs a first signal. When the load power supply is reversely connected, the current voltage is less than the reference voltage, so that the central control module outputs a second signal. When the central control module outputs the first signal, the driving component is used to connect the transistor to the driving power supply and drive the transistor to be in a conducting state, so that the power supply supplies power to the load. When the central control module outputs the second signal, the driving component is used to cut off the connection between the transistor and the driving power supply and drive the transistor to be in a cut-off state, so as to cut off the power supply from supplying power to the load, thereby realizing the anti-reverse connection function. Since the present application uses the combination of the central control module and the transistor to achieve the anti-reverse connection effect, on the one hand, it can achieve the effect of reducing power consumption. On the other hand, by using the comparison method to achieve the output signal effect, the reference voltage can be set relatively low, so that even when the input power supply voltage value is small, the transistor can still be completely turned on.

[0083] The foregoing is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0084] For those skilled in the art, it is obvious that the present application is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present application. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. An anti-reverse connection circuit, characterized in that, The reverse connection prevention circuit includes a central control module, a voltage dividing component, a driving component, and a transistor. The voltage dividing component is used to be electrically connected to the positive input terminal and the reverse input terminal of a load power supply, and the voltage dividing component is also electrically connected to the input terminal of the central control module. The output terminal of the central control module, the driving component, and the transistor are electrically connected in sequence. The transistor is also electrically connected to the input terminal of the load power supply. The driving component is also used to be electrically connected to a driving power supply. The positive input terminal and the reverse input terminal of the load power supply are also used to be electrically connected to a load; The central control module is used to receive the current voltage collected by the voltage dividing component, and output a first signal or a second signal according to the comparison result between the current voltage and a preset reference voltage. Wherein, when the load power supply is correctly connected and the current voltage is greater than the reference voltage, the central control module outputs the first signal; when the load power supply is reversely connected, the current voltage is less than the reference voltage, so that the central control module outputs the second signal; When the central control module outputs the first signal, the driving component is used to connect the transistor and the driving power supply, and drive the transistor to be in a conducting state, so that the load power supply supplies power to the load; When the central control module outputs the second signal, the driving component is used to cut off the connection between the transistor and the driving power supply, and drive the transistor to be in a cut-off state, so as to cut off the load power supply from supplying power to the load, prevent the load power supply from being reversely connected, and realize the input reverse connection protection function; The driving component includes an NPN transistor and a PNP transistor. The bases of the NPN transistor and the PNP transistor are both electrically connected to the output terminal of the central control module. The collector of the NPN transistor is electrically connected to the driving power supply. The emitter of the NPN transistor is respectively electrically connected to the emitter of the PNP transistor and the first end of the transistor. The collector of the PNP transistor is electrically connected to the second end of the transistor; When the central control module outputs the second signal, the NPN transistor is cut off, the PNP transistor is conducting, and the transistor is in a cut-off state.

2. The reverse connection prevention circuit according to claim 1, wherein The central control module is also used to output the second signal when the load power supply is correctly connected and the current voltage is less than the reference voltage.

3. The reverse connection prevention circuit according to claim 1, characterized in that The voltage dividing component is electrically connected to the positive input terminal of the central control module. The reverse connection prevention circuit further includes a hysteresis module. One end of the hysteresis module is respectively electrically connected to the driving component and the output terminal of the central control module. The other end of the hysteresis module is respectively electrically connected to the positive input terminal of the central control module and the voltage dividing component; The hysteresis module is used to feedback a part of the voltage of the driving power supply to the voltage dividing component after the central control module outputs the first signal, so as to maintain the conducting state of the transistor within a target voltage range when the load voltage fluctuates, so as to avoid the transistor from frequently conducting and cutting off.

4. The reverse connection prevention circuit according to claim 3, wherein The hysteresis module includes a diode and a first resistor. The anode of the diode is electrically connected to the driving component and the output terminal of the central control module respectively. The cathode of the diode is electrically connected to one end of the first resistor. The other end of the first resistor is electrically connected to the positive input terminal of the central control module and the voltage dividing component respectively.

5. The reverse connection prevention circuit according to claim 1, wherein The voltage dividing component includes a second resistor and a third resistor. One end of the second resistor is electrically connected to the positive input terminal of the load power supply. The other end of the second resistor is electrically connected to one end of the third resistor and the positive input terminal of the central control module respectively. The other end of the third resistor is electrically connected to the inverted input terminal of the load power supply.

6. The anti-reverse connection circuit according to claim 1, characterized in that, The voltage dividing component is electrically connected to the positive input terminal of the central control module. The reverse connection prevention circuit further includes a reference voltage module. The reference voltage module is electrically connected to the driving power supply and the inverted input terminal of the central control module respectively, so as to use the voltage output by the reference voltage module as the reference voltage of the central control module.

7. The anti-reverse connection circuit according to claim 6, characterized in that, The reference voltage module includes a fourth resistor and a voltage stabilizing diode. One end of the fourth resistor is used to be electrically connected to the driving power supply. The other end of the fourth resistor is electrically connected to the inverted input terminal of the central control module and the negative electrode of the voltage stabilizing diode respectively. The positive electrode of the voltage stabilizing diode is grounded.

8. The anti-reverse connection circuit according to claim 1, wherein The central control module includes a comparator and an operational amplifier.

9. An anti-reverse connection device, characterized in that, The reverse connection prevention device includes a load and the reverse connection prevention circuit according to any one of claims 1 to 8. The reverse connection prevention circuit is electrically connected to the input terminal of the load.

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