Power management circuit

Abstract

The utility model relates to a power management circuit which comprises a switching circuit, an under-voltage protection circuit and an overvoltage protection circuit. The switching circuit comprises an input end, an output end and a control end; the input end is electrically connected with the output end of a power supply, and the output end is electrically connected with the input end of a load; the control end is used for controlling the on and off of the switching circuit according to the output of the under-voltage protection circuit and the overvoltage protection circuit; the input ends of the under-voltage protection circuit and the overvoltage protection circuit are electrically connected with the output end of the power supply, and the output ends of the under-voltage protection circuit and the overvoltage protection circuit are electrically connected with the control end of the switching circuit; the under-voltage protection circuit is used for limiting a lower limit value of power supply output; the overvoltage protection circuit is used for limiting the upper limit value of power output, and the upper limit value is larger than the lower limit value. The power management circuit can output different voltages within a certain voltage range, so that the diversified voltage requirements of rear-end loads can be met.

Description

Technical Field

[0001] The present application relates to the technical field of protection circuits, and in particular to a power management circuit. Background Art

[0002] With the development of intelligent vehicles, more and more electronic devices are integrated into vehicles, providing users with more convenience and more driving pleasure; the built-in power supply of the car is used to provide a power interface for electronic devices outside the vehicle; in actual use, the voltage output by the power supply is unstable, and there are overvoltage, undervoltage and other conditions.

[0003] In the related art, a protection circuit is provided to solve the problem of overvoltage and undervoltage. However, the existing protection circuit enables the power supply to only provide a certain voltage for the back-end load, which is difficult to meet the diverse load voltage requirements. Utility Model Content

[0004] In order to solve the problem that the existing power management circuit can only output a specific voltage and is difficult to meet the diverse load voltage requirements, the present application provides a power management circuit.

[0005] According to one aspect of an embodiment of the present application, there is provided a power management circuit, including a switch circuit, an undervoltage protection circuit and an overvoltage protection circuit;

[0006] The switch circuit includes an input end, an output end and a control end; the input end is used to be electrically connected to the output end of the power supply, and the output end is used to be electrically connected to the input end of the load; the control end is used to control the closing and opening of the switch circuit according to the outputs of the undervoltage protection circuit and the overvoltage protection circuit;

[0007] The input ends of the undervoltage protection circuit and the overvoltage protection circuit are both electrically connected to the output end of the power supply, and the output ends of the undervoltage protection circuit and the overvoltage protection circuit are both electrically connected to the control end of the switch circuit;

[0008] The undervoltage protection circuit is used to limit the lower limit value of the power supply output; the overvoltage protection circuit is used to limit the upper limit value of the power supply output, and the upper limit value is greater than the lower limit value.

[0009] In one design, the overvoltage protection circuit includes a comparator U1; the undervoltage protection circuit includes a comparator U2;

[0010] One input terminal of the comparator U1 is used to input a first sampling voltage, and the other input terminal of the comparator U1 is used to input a first reference voltage;

[0011] One input terminal of the comparator U2 is used to input a second sampling voltage, and the other input terminal of the comparator U2 is used to input a second reference voltage.

[0012] In one design, the non-inverting input terminal of the comparator U1 is used to input the first sampling voltage, the inverting input terminal of the comparator U1 is used to input the first reference voltage, and a first hysteresis resistor R1 is provided between the inverting input terminal and the output terminal of the comparator U1;

[0013] The non-inverting input terminal of the comparator U2 is used to input the second sampling voltage, and the inverting input terminal of the comparator U2 is used to input the second reference voltage; a second hysteresis resistor R2 is provided between the inverting input terminal and the output terminal of the comparator U2.

[0014] In one design, a first voltage-dividing unit is further included, and the voltage-dividing unit includes a first voltage-dividing resistor R3, a second voltage-dividing resistor R4, and a third voltage-dividing resistor R5; the first voltage-dividing resistor R3, the second voltage-dividing resistor R4, and the third voltage-dividing resistor R5 are used to be arranged in series between a power supply and a ground terminal; wherein the input end of the first voltage-dividing resistor R4 is used to connect to a power supply, and the output end of the third voltage-dividing resistor R5 is used to be grounded;

[0015] The output end of the first voltage-dividing resistor R3 is electrically connected to the same-direction input end of the comparator U1;

[0016] The output end of the second voltage-dividing resistor R4 is electrically connected to the non-inverting input end of the comparator U2.

[0017] In one design, it further includes a second voltage dividing unit and a third voltage dividing unit, wherein the second voltage dividing unit is connected in parallel with the third voltage dividing unit;

[0018] The second voltage dividing unit includes a fourth voltage dividing resistor R6 and a fifth voltage dividing resistor R7 connected in series between the reference power supply and the ground potential; a node between the fourth voltage dividing resistor R6 and the fifth voltage dividing resistor R7 is electrically connected to the first sampling voltage input terminal of the comparator U1;

[0019] The third voltage-dividing unit includes a sixth voltage-dividing resistor R8 and a seventh voltage-dividing resistor R9 connected in series between the reference power supply and the ground potential; a node between the sixth voltage-dividing resistor R8 and the seventh voltage-dividing resistor R9 is electrically connected to the second sampling voltage input terminal of the comparator U2.

[0020] In one design, a filter unit is disposed at the output end of the comparator U1 and the output end of the comparator U2.

[0021] In one design, an inverting unit is further included. The inverting unit is arranged at the input end of the comparator U1 and is used to invert the output value of the comparator U1.

[0022] In one design, the inverting unit includes an NPN transistor Q3, the base of the transistor Q3 is electrically connected to the output end of the comparator U1, the collector of the transistor Q3 is electrically connected to the control end of the switch circuit, and the emitter of the transistor Q3 is grounded.

[0023] In one design, a load dump and surge protection circuit is also included, wherein the input end of the load dump and surge protection circuit is used to be electrically connected to the output end of the power supply, and the output end of the load dump and surge protection circuit is electrically connected to the control end of the switch circuit.

[0024] In one design, the switching circuit includes an NMOS tube and a PMOS tube, the gate of the NMOS tube is the control end of the switching circuit, the drain of the NMOS tube is grounded, the source of the NMOS tube is electrically connected to the gate of the PMOS tube, and the source and drain of the PMOS tube are used to be electrically connected to the output end of the power supply.

[0025] The power management circuit provided in the embodiment of the present application includes a switch circuit, an undervoltage protection circuit and an overvoltage protection circuit; the undervoltage protection circuit is used to limit the lower limit value of the power supply output, and the overvoltage protection circuit is used to limit the upper limit value of the power supply output; when the output voltage of the power supply is greater than the upper limit value, the switch circuit is disconnected; when the output voltage of the power supply is less than the lower limit value, the switch circuit is also disconnected; when the output voltage of the power supply is between the upper limit value and the lower limit value, the input end of the switch circuit is connected to the output end, and the power supply provides voltage to the load; since the upper limit value is greater than the lower limit value in the present application, the power protection circuit allows a certain range of voltage output rather than a specific voltage output; therefore, the power management circuit of the present application can output different voltages within a certain voltage range, so as to meet the diversified voltage requirements of the back-end load; in addition, in the present application, the undervoltage protection circuit and the overvoltage protection circuit are in parallel, so that when one of the undervoltage protection circuit and the overvoltage protection circuit fails, it will not affect the normal operation of the other protection circuit, so as to help improve the reliability of the power management circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other purposes, features and advantages of the embodiments of the present application will become more easily understood through the following detailed description with reference to the accompanying drawings. In the accompanying drawings, multiple embodiments of the present application will be described in an exemplary and non-limiting manner, wherein:

[0027] Figure 1 The figure is a structural block diagram of a power management circuit provided by an embodiment of the present application;

[0028] Figure 2 Shown is a structural diagram of a comparator used in an overvoltage protection circuit provided in an embodiment of the present application;

[0029] Figure 3 Shown is a structural diagram of a comparator used in an undervoltage protection circuit provided in an embodiment of the present application;

[0030] Figure 4 FIG. 1 is a schematic diagram of the structure of a first voltage dividing unit used in an undervoltage protection circuit and an overvoltage protection circuit provided in an embodiment of the present application;

[0031] Figure 5 Shown is a schematic structural diagram of a second voltage dividing unit and a third voltage dividing unit provided in an embodiment of the present application;

[0032] Figure 6 Shown is a structural schematic diagram of an overvoltage protection circuit and an undervoltage protection circuit provided in an embodiment of the present application;

[0033] Figure 7 Shown is a structural schematic diagram of a voltage management circuit provided in an embodiment of the present application.

[0034] Description of reference numerals:

[0035] 1- switch circuit; 2- undervoltage protection circuit; 3- overvoltage protection circuit; 4- power supply; 5- load; 6- first voltage divider unit; 7- second voltage divider unit; 8- third voltage divider unit; 9- reference power supply; 10- load dump and surge protection circuit. DETAILED DESCRIPTION

[0036] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The implementation methods provided in the embodiments of the present application can be combined with each other if there is no contradiction. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application.

[0037] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0038] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] The power management circuit provided in the embodiments of the present application is described in detail below in conjunction with the drawings in the specification of the present application.

[0040] Figure 1 The figure shows a structural block diagram of a power management circuit provided in an embodiment of the present application. Please refer to Figure 1 The power management circuit of the present application includes a switch circuit 1, an undervoltage protection circuit 2 and an overvoltage protection circuit 3; the switch circuit 1 includes an input end, an output end and a control end; the input end is used to be electrically connected to the output end of a power supply 4, and the output end is used to be electrically connected to the input end of a load 5; the control end is used to control the closing and opening of the switch circuit 1 according to the outputs of the undervoltage protection circuit 2 and the overvoltage protection circuit 3; the input ends of the undervoltage protection circuit 2 and the overvoltage protection circuit 3 are both electrically connected to the output end of the power supply 4, and the output ends of the undervoltage protection circuit 2 and the overvoltage protection circuit 3 are both electrically connected to the control end of the switch circuit 1; the undervoltage protection circuit 2 is used to limit the lower limit value of the output of the power supply 4; the overvoltage protection circuit 3 is used to limit the upper limit value of the output of the power supply 4, and the upper limit value is greater than the lower limit value.

[0041] For more details, please refer to Figure 1 In this application, the undervoltage protection circuit 2 is used to limit the lower limit value of the output of the power supply 4, and the overvoltage protection circuit 3 is used to limit the upper limit value of the output of the power supply 4; when the output voltage of the power supply 4 is greater than the upper limit value, the switch circuit 1 is disconnected; when the output voltage of the power supply 4 is less than the lower limit value, the switch circuit 4 is also disconnected; when the output voltage of the power supply 4 is between the upper limit value and the lower limit value, the input end and the output end of the switch circuit 1 are connected, and the power supply 4 provides voltage to the load 5; since the upper limit value in this application is greater than the lower limit value, the power protection circuit allows a certain range of voltage output, rather than a specific voltage output.

[0042] In one application scenario, the load end has multiple types of loads 5, and the operating voltages of each load 5 are different; the specific voltage output by the existing power management circuit is difficult to meet the demand; the power management circuit of the present application can output different voltages within a certain voltage range, thereby meeting the diverse voltage requirements of the back-end loads.

[0043] In addition, in the present application, the undervoltage protection circuit 2 and the overvoltage protection circuit 3 are connected in parallel. In this way, when one of the undervoltage protection circuit 2 and the overvoltage protection circuit 3 fails, it will not affect the normal operation of the other protection circuit. This helps to improve the reliability of the power management circuit.

[0044] Figure 2 Shown is a structural diagram of a comparator used in an overvoltage protection circuit provided in an embodiment of the present application; Figure 3 The structure diagram of the comparator used in the undervoltage protection circuit provided in the embodiment of the present application is shown; Figure 1 , Figure 2 and Figure 3 In the present application, the overvoltage protection circuit 3 includes a comparator U1; the undervoltage protection circuit 2 also includes a comparator U2; one input end of the comparator U1 is used to input a first sampling voltage V1, and the other input end of the comparator U1 is used to input a first reference voltage V1′; one input end of the comparator U2 is used to input a second sampling voltage V2, and the other input end of the comparator U2 is used to input a second reference voltage V2′.

[0045] Please combine Figure 1 , Figure 2 and Figure 3 Specifically, in the overvoltage protection circuit, a first sampling voltage V1 is input to one input end of the comparator U1, and a first reference voltage V1′ is input to the other input end of the comparator U1; the level of the first sampling voltage V1 represents the level of the output voltage of the power supply 4, and the first reference voltage V1′ represents the upper limit of the voltage allowed to be output by the power supply 4. When the first sampling voltage V1 is greater than the first reference voltage V1′, the overvoltage protection circuit will output a control signal for turning off the switch circuit, so that the power supply between the power supply 4 and the load 5 is disconnected, thereby preventing the load 5 from working under an excessively high voltage, which helps to improve the use of the load. safety; in the undervoltage protection circuit 2, a second sampling voltage V2 is input to one input end of the comparator U2, and a second reference voltage V2′ is input to the other input end of the comparator U2; the level of the second sampling voltage V2 represents the level of the output voltage of the power supply 4, and the second reference voltage V2′ represents the lower limit of the voltage allowed to be output by the power supply 4. When the second sampling voltage V2 is less than the second reference voltage V2′, the undervoltage protection circuit will output a control signal for turning off the switch circuit. In this way, the power supply between the power supply 4 and the load 5 is disconnected, thereby preventing the load 4 from working at an excessively low voltage, which helps to protect the load.

[0046] It should be noted that there are many ways to achieve circuit overvoltage protection or undervoltage protection. For example, it can be achieved by using a combination of resistors, transistors, and diodes, but the circuit composition structure is relatively complex. The present application uses a comparator to achieve undervoltage and overvoltage protection, which has the characteristics of simple structure, reliable operation, and easy connection.

[0047] Please continue to refer to Figure 2 and Figure 3 The same-direction input terminal of the comparator U1 is used to input the first sampling voltage V1, the reverse input terminal of the comparator U1 is used to input the first reference voltage V1′, and a first hysteresis resistor R1 is arranged between the reverse input terminal and the output terminal of the comparator U1; the same-direction input terminal of the comparator U2 is used to input the second sampling voltage V2, the reverse input terminal of the comparator U2 is used to input the second reference voltage V2′; a second hysteresis resistor R2 is arranged between the reverse input terminal and the output terminal of the comparator U2.

[0048] Specifically, in some application scenarios of the present application, such as the in-car power supply of a car; the in-car power supply is used to power electronic equipment outside the car, such as an external car phone, portable DVD, mobile phone charger, laptop computer, digital camera, car refrigerator, camera, etc.; currently, the output of the in-car power supply is unstable, and there are overvoltage, undervoltage and other conditions; in addition, the in-car power supply will also be interfered by other electronic module systems, and the output voltage may fluctuate around the upper limit and lower limit. This may cause the output state of comparator U1 and comparator U2 to change with the fluctuation, causing the switching circuit to frequently open and close, affecting the normal operation of the electronic equipment.

[0049] In response to the above situation, the present application sets a first hysteresis resistor R1 between the reverse input terminal and the output terminal of the comparator U1, so that the comparator U1 can have a certain tolerance range near the upper limit value, thereby avoiding the phenomenon of frequent changes in the state of the output terminal of the comparator U1 caused by voltage disturbances; similarly, the present application sets a second hysteresis resistor R2 between the reverse input terminal and the output terminal of the comparator U2, so that the comparator U2 can have a certain tolerance range near the lower limit value, thereby avoiding frequent changes in the state of the output terminal of the comparator U2 caused by smaller voltage disturbances of the electronic module; therefore, the present application can improve the working reliability of the load end by setting the first hysteresis resistor R1 and the second hysteresis resistor R2.

[0050] Figure 4 FIG. 1 is a schematic diagram showing the structure of the first voltage divider unit used in the undervoltage protection circuit and the overvoltage protection circuit provided in the embodiment of the present application; please refer to FIG. Figure 1 , Figure 2 , Figure 3 and Figure 4In some embodiments of the application, the power management circuit of the present application also includes a first voltage-dividing unit 6, which includes a first voltage-dividing resistor R3, a second voltage-dividing resistor R4 and a third voltage-dividing resistor R5; the first voltage-dividing resistor R3, the second voltage-dividing resistor R4 and the third voltage-dividing resistor R5 are used to be arranged in series between the power supply 4 and the ground terminal; wherein the input end of the first voltage-dividing resistor R4 is used to connect the power supply, and the output end of the third voltage-dividing resistor R5 is used to be grounded; the output end of the first voltage-dividing resistor R3 is electrically connected to the same-direction input end of the comparator U1; the output end of the second voltage-dividing resistor R4 is electrically connected to the same-direction input end of the comparator U2.

[0051] Generally speaking, the output voltage of a power supply is relatively large, usually above 10V; while the operating voltage of a comparator is generally 3-5V, which is much lower than the output voltage of the power supply; in order for the comparator to work properly, the output voltage of the power supply must be changed so that the comparator can be used normally.

[0052] The present application utilizes the first voltage divider unit 6 to divide the output voltage of the power supply 4, thereby satisfying the working conditions of the comparator U1 and the comparator U2; please continue to refer to Figure 4 , Figure 4 In the figure, the first voltage-dividing resistor R3, the second voltage-dividing resistor R4 and the third voltage-dividing resistor R5 are connected in series, the input end of the first voltage-dividing resistor R4 is connected to the power supply, and the output end of the third voltage-dividing resistor R5 is used for grounding; in this way, the output voltage of the power supply 4 is divided by the first voltage-dividing resistor R3, the second voltage-dividing resistor R4 and the third voltage-dividing resistor R5, and the voltage divided by the third resistor R3 is input to the comparator U2 as the second sampling voltage V2 of the comparator U2; the voltage divided by the sum of the second voltage-dividing resistor R4 and the third voltage-dividing resistor R5 is input to the comparator U1 as the first sampling voltage V1 of the comparator U1; V1 is greater than V2, and V1 and V2 can meet the working conditions of the comparators U1 and U2.

[0053] Please continue to refer to Figure 4 ,from Figure 4 It can be seen that the first voltage divider unit 6 is both a sampling unit of the comparator U1 and a sampling unit of the comparator U2; that is, the sampling units of the comparator U1 and the comparator U2 are connected in series, which helps to simplify the overall structure of the power management circuit.

[0054] certainly, Figure 4 Only one structural form of the voltage divider unit is illustrated; in other implementations of the present application, the comparator U1 and the comparator U2 may have independent voltage divider units.

[0055] It should also be noted that Figure 4The voltage divider unit shown is only used to represent the sampling mode of the comparator U1 and the comparator U2 in this application. The number and size of the voltage divider resistors included in the voltage divider unit can be selected according to actual conditions and are not limited to Figure 4 Number of resistors shown.

[0056] Figure 5 The diagram shows the structure of the second voltage divider unit and the third voltage divider unit provided in the embodiment of the present application; Figure 1 , Figure 2 and Figure 5 In some embodiments of the application, the power management circuit also includes a second voltage-dividing unit 7 and a third voltage-dividing unit 8, and the second voltage-dividing unit 7 is connected in parallel with the third voltage-dividing unit 8; the second voltage-dividing unit 7 includes a fourth voltage-dividing resistor R6 and a fifth voltage-dividing resistor R7 connected in series between a reference power supply 9 and a ground potential; the node between the fourth voltage-dividing resistor R6 and the fifth voltage-dividing resistor R7 is electrically connected to the first sampling voltage input terminal of the comparator U1; the third voltage-dividing unit 8 includes a sixth voltage-dividing resistor R8 and a seventh voltage-dividing resistor R9 connected in series between the reference power supply and the ground potential; the node between the sixth voltage-dividing resistor R8 and the seventh voltage-dividing resistor R9 is electrically connected to the second sampling voltage input terminal of the comparator U2.

[0057] Please continue to refer to Figure 1 , Figure 2 , Figure 3 and Figure 5 Based on the above, the reference voltage of the comparator U1 represents the upper limit of the voltage output by the power management circuit, and the reference voltage of the comparator U2 represents the lower limit of the voltage output by the power management circuit; depending on the different working voltages required by the back-end load, the upper limit and the lower limit may change. The present application divides the output voltage of the reference power supply by the second voltage divider unit 7 and the third voltage divider unit 8 to meet the setting requirements of the reference voltages of the comparator U1 and the comparator U2; Figure 5 From the structure shown, in some embodiments of the present application, the comparator U1 and the comparator U2 each use an independent voltage divider unit, so that the reference voltage of the comparator U1 and the reference voltage of the comparator U2 do not affect each other, and the reference voltage of the comparator U1 and the reference voltage of the comparator U2 will be more accurate, so that the reliability of the undervoltage protection circuit and the overvoltage protection circuit can be improved.

[0058] Based on the above statements, in some embodiments of the application, since the sampling voltages of the comparator U1 and the comparator U2 are within a certain voltage range, the sampling ends of the comparator U1 and the comparator U2 can share a voltage divider unit; in this way, the composition structure of the power management circuit can be simplified; at the same time, the reference voltages of the comparator U1 and the comparator U2 use their own independent voltage divider units, so that the accuracy of setting the reference voltages of the comparator U1 and the comparator U2 can be improved; therefore, the power management circuit of this embodiment has the advantages of simple structure and high working reliability to a certain extent.

[0059] Figure 6 The figure shows a schematic diagram of the structure of the overvoltage protection circuit and the undervoltage protection circuit provided in the embodiment of the present application; Figure 1 , Figure 2 , Figure 3 , Figure 5 and Figure 6 In some embodiments of the present application, the power management circuit further includes a reversing unit, which is disposed at the output end of the comparator U1 and is used to reverse the output of the comparator U1.

[0060] Specifically, based on the foregoing, in order to avoid interference of other electronic module systems with the under-protection circuit 2 or the overvoltage protection circuit 3, the same-direction input terminal of the comparator U1 is used to input the first sampling voltage V1, the reverse input terminal of the comparator U1 is used to input the first reference voltage V1′, and a first hysteresis resistor R1 is arranged between the reverse input terminal and the output terminal of the comparator U1; the same-direction input terminal of the comparator U2 is used to input the second sampling voltage V2, and the reverse input terminal of the comparator U2 is used to input the second reference voltage V2′; a second hysteresis resistor R2 is arranged between the reverse input terminal and the output terminal of the comparator U2. In this way, when the voltage value output by the power supply 4 is greater than the upper limit value, the first sampling voltage V1 is greater than the first reference voltage V1′, and the comparator U1 will output a high level; when the voltage value output by the power supply is less than the lower limit value, the second sampling voltage V2 is less than the second reference voltage V2′, and the comparator U2 will output a low level; in both cases, it is necessary to cut off the switch circuit 1 to disconnect the power supply between the power supply 4 and the load 5; based on this, the present application sets a reverse unit at the output end of the comparator U1, so that the overvoltage protection circuit 3 also outputs a low level in the case of overvoltage; then, whether the output voltage of the power supply 4 is in an undervoltage state or an overvoltage state, the signal sent to the control end of the switch circuit 1 is a low level, and therefore, the switch circuit 1 only needs to cut off the power supply between the power supply and the load under a low level, which has the advantage of simple control logic and helps to simplify the structure of the switch circuit.

[0061] Figure 7 The figure shows a schematic diagram of a voltage management circuit provided in an embodiment of the present application; please refer to Figure 7In some embodiments of the present application, the reverse unit includes an NPN transistor Q3, the base of the transistor Q3 is electrically connected to the output end of the comparator U1, the collector of the transistor Q3 is electrically connected to the control end of the switch circuit, and the emitter of Q3 is grounded.

[0062] Specifically, when the comparator U1 outputs a high level, the transistor Q3 is turned on to output a low level, thereby realizing the reversal of the output of the comparator U1; the embodiment of the present application uses the transistor Q3 for reversal, which has the advantages of simple structure and low price; the structure for reversing the output of the comparator U1 is not limited to the NPN transistor Q3 mentioned in the embodiment of the present application, and other forms can also be used as substitutes, such as a NOT gate or an inverter.

[0063] Please continue to refer to Figure 7 In some embodiments of the present application, the power management circuit also includes a load dump and surge protection circuit 10, the input end of the load dump and surge protection circuit 10 is used to be electrically connected to the output end of the power supply 4, and the output end of the load dump and surge protection circuit 10 is electrically connected to the control end of the switching circuit 1.

[0064] Specifically, in some application scenarios of the present application, such as the in-vehicle power supply of a car, the in-vehicle power supply may be interfered with by other electronic module systems, resulting in load dumping and surge conditions. Load dumping and surge conditions can easily cause damage to electronic equipment. In this regard, the present application provides a load dumping and surge protection circuit to protect the rear-end load.

[0065] Please continue to refer to Figure 7 In some embodiments of the present application, the load dump and surge protection circuit includes an NPN transistor Q5, a voltage-dumping diode D1, a tenth voltage-dividing resistor R10 and an eleventh voltage-dividing resistor R11; the cathode of the voltage-dumping diode D1 is electrically connected to the output end of the power supply 4, the anode of the voltage-dumping diode D1 is connected to one end of the tenth voltage-dividing resistor R10, the other end of the tenth voltage-dividing resistor R10 is connected to one end of the eleventh voltage-dividing resistor R11, and the other end of the eleventh voltage-dividing resistor R11 is grounded; the base of the transistor Q5 is connected to the node between the tenth voltage-dividing resistor R10 and the eleventh voltage-dividing resistor R11, the collector of the transistor Q5 is connected to the control end of the switch circuit 1, and the emitter of the transistor Q5 is grounded; in this way, in the case of load dump and surge, when the output voltage Vbat of the power supply 4 reaches a certain voltage value, when the voltage-dividing condition of the other end of the tenth voltage-dividing resistor R10 and the eleventh voltage-dividing resistor R11 reaches the turn-on condition of the transistor Q5, Q5 works to output a low level, and the switch circuit 1 is turned off, thereby achieving the purpose of protecting the subsequent load.

[0066] It should be noted that in some embodiments of the present application, the load dump and surge protection circuit 10, the undervoltage protection circuit 2, and the overvoltage protection circuit 3 provided in the embodiments of the present application all trigger the switch circuit 1 to cut off the power supply between the power supply 4 and the load 5 when the output is at a low level. The logic of shutting down and closing the power supply 4 is relatively simple, which helps to simplify the structure of the switch circuit 1, and then helps to simplify the circuit structure of the overall power supply pipeline.

[0067] also, Figure 7 Only one implementation form of the load dump and surge protection circuit 10 is provided; the load dump and surge protection circuit may also adopt other structures, such as using a plurality of resistors and diodes to form the load dump and surge protection circuit.

[0068] Please continue to refer to Figure 7 In some embodiments of the present application, the switching circuit 1 includes an NMOS tube Q2 and a PMOS tube Q1, the gate of the NMOS tube Q2 is the control end of the switching circuit, the drain of the NMOS tube Q3 is grounded, the source of the NMOS tube Q2 is electrically connected to the gate of the PMOS tube Q1, and the source and drain of the PMOS tube Q1 are used to be electrically connected to the output end of the power supply 4.

[0069] Specifically, when the output voltage Vbat of the power supply 4 is undervoltage, overvoltage, load dumping, surge, etc., the corresponding undervoltage protection circuit, overvoltage protection circuit, load dumping, surge protection circuit will output a low level. At this time, the NMOS tube Q2 is turned off, and then the PMOS tube Q1 is turned off. In this way, the power supply circuit between the power supply 4 and the load 5 is disconnected.

[0070] Please continue to refer to Figure 7 In practical applications, the switch circuit 1 will also include some voltage divider resistors, such as Figure 7 The twelfth voltage-dividing resistor R12 and the twelfth voltage-dividing resistor R13 shown in the figure divide the output voltage of the power supply 1 to ensure that the PMOS tube Q1 is turned on in a normal state.

[0071] Please continue to refer to Figure 7 When the present application is used for an in-vehicle power supply, the control end of the switch circuit 1, that is, the gate of the NMOS tube Q2, will input the ignition signal ACC through the diode. When the car is ignited, the NMOS tube Q2 will be turned on, and then the PMOS tube Q1 will be turned on. Under normal conditions, the power supply 4 supplies power to the rear-end load 5; based on the same reason as above, the switch circuit 1 will also include a fourteenth voltage-dividing resistor R14 and a fifteenth voltage-dividing resistor R15. The fourteenth voltage-dividing resistor R14 and the fifteenth voltage-dividing resistor R15 are used to divide the input voltage to ensure that the NMOS tube Q2 is turned on under normal conditions.

[0072] It should also be noted that Figure 7 Only one structural form of the switching circuit is illustrated. In practical applications, other types of transistors can also be combined with MOS tubes. The advantage of MOS tubes is that the current is large. MOS tubes are generally used for circuits with high load current requirements, and ordinary transistors can be used for circuits with small current requirements.

[0073] Please continue to refer to Figure 7 In some implementations of the present application, a filter unit is provided at the input end of the comparator U1 and the comparator U2.

[0074] In some application scenarios of the present application, there are many interference signals around the comparator U1 and the comparator U2. Therefore, a filter unit is set at the input end of the comparator U1 and the comparator U2. The filter unit can reduce the influence of the interference signal entering the input end of the comparator U1 and the comparator U2, which helps to improve the reliability of the comparator U1 and the comparator U2. Please continue to refer to Figure 7 ,like Figure 7 The capacitors in the figure are all filter capacitors.

[0075] Please continue to refer to Figure 7 In some embodiments of the present application, a diode D2 is further provided between the output end of the power supply 4 and the input end of the switch circuit 1; the function of the diode D2 is mainly to prevent reverse connection, which may cause damage to the circuit.

[0076] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned implementation modes, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned implementation modes can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the implementation modes of the present application.

Claims

1. A power management circuit, characterized in that: It comprises a switch circuit (1), an undervoltage protection circuit (2) and an overvoltage protection circuit (3); The switch circuit (1) comprises an input end, an output end and a control end; the input end is used to be electrically connected to the output end of a power source (4), and the output end is used to be electrically connected to the input end of a load (5); the control end is used to control the closing and opening of the switch circuit (1) according to the outputs of the undervoltage protection circuit (2) and the overvoltage protection circuit (3); The input ends of the undervoltage protection circuit (2) and the overvoltage protection circuit (3) are both electrically connected to the output end of the power supply (4), and the output ends of the undervoltage protection circuit (2) and the overvoltage protection circuit (3) are both electrically connected to the control end of the switch circuit (1); The undervoltage protection circuit (2) is used to limit the lower limit value of the output of the power supply (4); the overvoltage protection circuit (3) is used to limit the upper limit value of the output of the power supply (4), and the upper limit value is greater than the lower limit value; the overvoltage protection circuit (3) comprises a comparator U1; The undervoltage protection circuit (2) comprises a comparator U2; One input terminal of the comparator U1 is used to input a first sampling voltage, and the other input terminal of the comparator U1 is used to input a first reference voltage; One input terminal of the comparator U2 is used to input a second sampling voltage, and the other input terminal of the comparator U2 is used to input a second reference voltage.

2. The power management circuit according to claim 1, characterized in that: The non-inverting input terminal of the comparator U1 is used to input a first sampling voltage, the inverting input terminal of the comparator U1 is used to input a first reference voltage, and a first hysteresis resistor R1 is provided between the inverting input terminal and the output terminal of the comparator U1; The non-inverting input terminal of the comparator U2 is used to input the second sampling voltage, and the inverting input terminal of the comparator U2 is used to input the second reference voltage; a second hysteresis resistor R2 is provided between the inverting input terminal and the output terminal of the comparator U2.

3. The power management circuit according to claim 1 or 2, characterized in that: The power management circuit further comprises a first voltage dividing unit (6), the first voltage dividing unit (6) comprising a first voltage dividing resistor R3, a second voltage dividing resistor R4 and a third voltage dividing resistor R5; the first voltage dividing resistor R3, the second voltage dividing resistor R4 and the third voltage dividing resistor R5 are arranged in series between the power supply (4) and a grounding terminal; wherein the input end of the first voltage dividing resistor R4 is used for connecting to the power supply (4), and the output end of the third voltage dividing resistor R5 is used for grounding; The output end of the first voltage-dividing resistor R3 is electrically connected to the same-direction input end of the comparator U1; The output end of the second voltage-dividing resistor R4 is electrically connected to the non-inverting input end of the comparator U2.

4. The power management circuit according to claim 3, characterized in that: The power management circuit further comprises a second voltage dividing unit (7), a third voltage dividing unit (8) and a reference power supply (9), wherein the second voltage dividing unit (7) and the third voltage dividing unit (8) are connected in parallel; The second voltage dividing unit (7) comprises a fourth voltage dividing resistor R6 and a fifth voltage dividing resistor R7 connected in series between the reference power supply (9) and the ground; a node between the fourth voltage dividing resistor R6 and the fifth voltage dividing resistor R7 is electrically connected to the first sampling voltage input terminal of the comparator U1; The third voltage-dividing unit (8) comprises a sixth voltage-dividing resistor R8 and a seventh voltage-dividing resistor R9 connected in series between the reference power supply (9) and the ground potential; a node between the sixth voltage-dividing resistor R8 and the seventh voltage-dividing resistor R9 is electrically connected to the second sampling voltage input terminal of the comparator U2.

5. The power management circuit according to claim 1 or 2, characterized in that: The output ends of the comparator U1 and the comparator U2 are both provided with filtering units.

6. The power management circuit according to claim 1 or 2, characterized in that: It also includes an inverting unit, which is arranged at the input end of the comparator U1 and is used to invert the output value of the comparator U1.

7. The power management circuit according to claim 6, characterized in that: The inverting unit comprises an NPN transistor Q3, the base of the transistor Q3 is electrically connected to the output end of the comparator U1, the collector of the transistor Q3 is electrically connected to the control end of the switch circuit (1), and the emitter of the transistor Q3 is grounded.

8. The power management circuit according to claim 1, characterized in that: It also includes a load dump and surge protection circuit (10), wherein the input end of the load dump and surge protection circuit (10) is used to be electrically connected to the output end of the power supply (4), and the output end of the load dump and surge protection circuit (10) is electrically connected to the control end of the switch circuit (1).

9. The power management circuit according to any one of claims 1, 2, 4 and 7, characterized in that: The switch circuit (1) comprises an NMOS tube and a PMOS tube, the gate of the NMOS tube is the control end of the switch circuit (1), the drain of the NMOS tube is grounded, the source of the NMOS tube is electrically connected to the gate of the PMOS tube, and the source and drain of the PMOS tube are used to be electrically connected to the output end of the power supply (4).

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