Power supply switch circuit and power-consuming equipment

Abstract

The present application proposes a power supply switch circuit and an electrical device. The power supply switch circuit includes an NMOS transistor, a control module, a charge and discharge module, a switching power supply and a load; the control module is used to output an indication voltage to the charge and discharge module; the charge and discharge module is used to connect the switching power supply and the gate of the transistor when the indication voltage is at a high level, so as to switch the drain of the transistor and the source of the transistor to an on state; when the indication voltage is at a low level, the fourth terminal is connected to the gate of the transistor to switch the drain of the transistor and the source of the transistor to an off state. The switching of the high and low levels output by the third terminal of the charge and discharge module is realized to switch the on and off state of the transistor, thereby realizing the control of the entire circuit switch. Compared with the existing scheme, the NMOS transistor has a higher switching frequency, a shorter half-conduction time, less heat generated, and lower switching losses of the switching element.

Description

Technical Field

[0001] The present application relates to the field of switches, and in particular, to a power supply switch circuit and electrical equipment. Background Art

[0002] With the progress of science and social development, human society has used more and more forms of electricity and has become more and more dependent on it. Various electrical equipment are widely used in various industries and fields. And electrical equipment often needs to be equipped with switches to control the equipment. The sensitivity and quality of the switch determine the response speed and failure frequency of the electrical equipment to a certain extent.

[0003] Existing circuit switches are mostly implemented by relays, but relay switches have the problems of slow response speed and short service life. It is possible that the equipment may be damaged due to switch failure. Summary of the invention

[0004] The purpose of this application is to provide a power supply switch circuit and an electrical device to solve the above problems.

[0005] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides a power supply switch circuit, the power supply switch circuit comprising an NMOS transistor, a control module, a charge and discharge module, a switch power supply, and a load, wherein the positive electrode of the load is connected to the positive electrode of the power supply, the negative electrode of the load is connected to the drain of the NMOS transistor, and the source of the NMOS transistor is connected to the negative electrode of the power supply;

[0007] The charging and discharging module comprises a first end, a second end, a third end and a fourth end, wherein the first end is connected to the switching power supply, the second end is connected to the control module, the third end is connected to the gate of the NMOS transistor, and the fourth end is connected to the negative power supply electrode;

[0008] The control module is used to output an indication voltage to the charge and discharge module;

[0009] The charging and discharging module is used to connect the switching power supply and the gate of the NMOS transistor when the indication voltage is at a high level, and disconnect the fourth terminal from the gate of the NMOS transistor to switch the drain of the NMOS transistor and the source of the NMOS transistor to a conducting state;

[0010] The charge and discharge module is also used to disconnect the switching power supply from the gate of the NMOS transistor when the indication voltage is at a low level, and connect the fourth end to the gate of the NMOS transistor to switch the drain of the NMOS transistor and the source of the NMOS transistor to a disconnected state.

[0011] Further, the control module includes an operational amplifier, a reference voltage unit and a control voltage unit, the control voltage unit is connected to the non-inverting input terminal of the operational amplifier, the reference voltage unit is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the second terminal;

[0012] The control voltage unit is used to output a control voltage to the in-phase input terminal;

[0013] The reference voltage unit is used to output a reference voltage to the inverting input terminal;

[0014] The operational amplifier is used for, when the control voltage is higher than the reference voltage, the output end outputs a high-level indication voltage to the second end; and is also used for, when the control voltage is lower than the reference voltage, the output end outputs a low-level indication voltage to the second end.

[0015] Furthermore, the positive power supply terminal of the operational amplifier is connected to the switching power supply, and the negative power supply terminal of the operational amplifier is connected to the negative power supply electrode and the ground respectively.

[0016] Furthermore, the control module further includes a first capacitor, one end of the first capacitor is connected to the switching power supply, and the other end of the first capacitor is connected to the ground.

[0017] Further, the control voltage unit includes a first resistor and a second resistor, and the reference voltage unit includes a third resistor and a voltage divider;

[0018] One end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to the negative power supply electrode, the in-phase input terminal is connected between the first resistor and the second resistor, and the other end of the first resistor is connected to the control signal input terminal;

[0019] One end of the third resistor is connected to one end of the voltage divider, the other end of the third resistor is connected to the switching power supply, the other end of the voltage divider is connected to the negative power supply electrode, and the inverting input end is connected between the third resistor and the voltage divider.

[0020] Furthermore, the control module also includes a diode and a fourth resistor, the anode of the diode is connected to the output end, the cathode of the diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected between the second resistor and the in-phase input end.

[0021] Furthermore, the voltage divider is a voltage regulator tube, a fifth resistor or an equal voltage reference IC.

[0022] Furthermore, the control module also includes a sixth resistor, one end of the sixth resistor is connected to the output end, and the other end of the sixth resistor is connected to the second end.

[0023] Further, the charging and discharging module includes a first transistor and a second transistor, the first transistor is an NPN transistor, the second transistor is a PNP transistor, the first end is the collector of the first transistor, the fourth end is the collector of the second transistor, the base of the first transistor and the base of the second transistor are both connected to the second end, and the emitter of the first transistor and the emitter of the second transistor are both connected to the third end.

[0024] In a second aspect, an embodiment of the present application provides an electrical device, wherein the electrical device includes the power supply switch circuit described above.

[0025] Compared with the prior art, the beneficial effects of a power supply switch circuit and an electrical device provided by the embodiment of the present application are as follows: the power supply switch circuit includes an NMOS transistor, a control module, a charge and discharge module, a switch power supply and a load; the control module is used to output an indication voltage to the charge and discharge module; the charge and discharge module is used to connect the switch power supply and the gate of the NMOS transistor when the indication voltage is at a high level, so as to switch the drain of the NMOS transistor and the source of the NMOS transistor to a conducting state; and is also used to connect the fourth end and the gate of the NMOS transistor when the indication voltage is at a low level, so as to switch the drain of the NMOS transistor and the source of the NMOS transistor to a disconnected state. By controlling the circuit switching of the conduction with the gate of the NMOS transistor, the switching of the on and off state of the NMOS transistor is realized, thereby realizing the control of the entire circuit switch. Compared with the existing scheme, the NMOS transistor has a higher switching frequency, a shorter half-conduction time, less heat generated, and lower switching loss of the switch element.

[0026] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A connection diagram of a PMOS switch circuit provided in an embodiment of the present application;

[0029] Figure 2 A connection diagram of a power switch circuit provided in an embodiment of the present application;

[0030] Figure 3 A connection diagram of a control module provided in an embodiment of the present application;

[0031] Figure 4 A connection diagram of the charging and discharging module provided in an embodiment of the present application.

[0032] In the figure: 10 - control module; 20 - charge and discharge module; 30 - switching power supply; 40 - load; 101 - control voltage unit; 102 - reference voltage unit. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] 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 for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0035] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so 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 this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0037] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do 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 should not be understood as a limitation on the present application.

[0038] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] When a circuit or device that realizes a certain function is powered by direct current, it is necessary to control the switching state of the power supply circuit between open and closed. Common DC power supply switching circuits use PMOS transistors (P-Metal-Oxide-Semiconductor) as switches.

[0041] Please refer to Figure 1 , Q4 is a PMOS transistor, Q5 is an NPN transistor, + is the positive input, - is the negative input, DRIVE is the control signal, which controls the opening and closing of Q4. Specifically, there are the following two situations:

[0042] First, when the DRIVE input is high, the current flows through the resistor R8, turning on the transistor Q5. Then, the current flows from VIN+ through R7, R9 and Q5 in sequence. Assuming the input voltage is 24V, and the resistance values ​​of R7 and R9 are the same, the voltage across R7 is 12V, that is, the gate of Q4 is 12V lower than the source low voltage, Q4 is fully turned on, and the power supply circuit is turned on.

[0043] Second, when the DRIVE input is low, no current flows through resistor R8, transistor Q5 is turned off, no current flows through R7, R9 and Q5, the gate and source potentials of Q4 are the same, Q4 is turned off, and the power supply circuit is disconnected.

[0044] After extensive practice, observation and summary, the inventor discovered the following technical shortcomings.

[0045] 1. When the input voltage (VIN+) is very low, such as 1V, Q4 will not be turned on, because the PMOS needs a voltage threshold between its gate and source to turn on, and the voltage threshold generally needs to be greater than 1V.

[0046] 2. Q4 cannot switch the switch state quickly and the switching loss is large.

[0047] Assume that the model of Q4 is si7155dp. According to the data sheet, its relevant parameters are shown in Table 1.

[0048]

[0049] Table 1

[0050] The parasitic capacitance Ciss between the gate and source of Q4 is 12900pF, and the input voltage is 24V. When Q4 is turned on, the maximum current charging Ciss is 24V / 20K=1.2mA. When Q4 is turned off, the maximum current discharging Ciss is 12V / 20K=0.6mA. Assuming that the Ciss charging current is always 1.2mA when turned on, Q4 is fully turned on when the voltage between the gate and source of Q4 is 5V, and the Q4 turn-on time is T=12900*5 / 1.2=53.75(uS). Assuming that the Ciss discharge current is always 0.6mA when turned off, Q4 is fully turned off when the voltage between the gate and source of Q4 is 0V, and the Q4 turn-off time is T=12900*5 / 0.6=107.5(uS). The total switching time is 161.25uS. Assuming that Q4 is turned on and then turned off immediately, and then turned on immediately after being turned off, the corresponding maximum switching frequency is about 1 / 161.25uS = 6.2kHz. If the switching frequency needs to be greater than 6.2kHz, design the circuit according to the parameters in Table 1. Figure 1 The circuit shown does not meet the usage requirements.

[0051] At the same time, because the process of Q4 turning on and off lasts for a long time, its half-conduction lasts for a long time. When it is half-conducted, the on-resistance of Q4 is very large. When a large current flows through it, it will lose a lot of power. Figure 1 The circuit shown will cause large power loss in Q4 when used for high-frequency switching, which may cause Q4 to heat up severely and be damaged, which may lead to reduced power supply efficiency, higher temperature rise, reduced reliability and shortened life of the product.

[0052] In order to solve the above problems, the present application embodiment provides a power supply switch circuit, such as Figure 2As shown, the power supply switch circuit includes an NMOS (N-Metal-Oxide-Semiconductor) transistor Q3, a control module 10, a charge and discharge module 20, a switching power supply 30, and a load 40. The positive electrode of the load 40 is connected to the positive electrode of the power supply, the negative electrode of the load 40 is connected to the drain (D) of the NMOS transistor Q3, and the source (S) of the NMOS transistor Q3 is connected to the negative electrode of the power supply.

[0053] The charge and discharge module 20 comprises a first terminal connected to the switch power supply 30, a second terminal connected to the control module 10, a third terminal connected to the gate (G) of the NMOS transistor Q3, and a fourth terminal connected to the negative power supply electrode.

[0054] The control module 10 is used to output an indication voltage to the charge and discharge module 20 .

[0055] The indication voltage may be a high level or a low level, and different levels represent different requirements.

[0056] The charge and discharge module 20 is used to connect the switch power supply 30 and the gate of the NMOS transistor Q3 when the indication voltage is at a high level, and disconnect the fourth terminal from the gate of the NMOS transistor Q3 to switch the drain of the NMOS transistor Q3 and the source of the NMOS transistor Q3 to a conducting state.

[0057] Specifically, the switching power supply 30 is connected to the gate of the NMOS transistor Q3, and the charging current in the circuit charges the capacitance (Ciss) between the gate and source of the NMOS transistor Q3. The voltage between the gate and source of the NMOS transistor Q3 rises. Once the voltage between the gate and source of the NMOS transistor Q3 exceeds the turn-on threshold of Q3, the drain and source of the NMOS transistor Q3 are switched to the on state. The positive power supply electrode and the negative power supply electrode are connected, and the load 40 can be powered.

[0058] Assuming that the maximum DC current of the charging current is 1A, the capacitance between the gate and source of the NMOS transistor Q3 is charged with a current of 1A. Assuming that the model of Q3 is BSC010N04LS6, according to the data sheet, its relevant parameters are shown in Table 2, and its Ciss is 4600pF. Assuming that Q3 is fully turned on when the gate-to-source voltage reaches 5V, the time required for the gate-to-source level of Q3 to reach 5V from 0V is: 4600*5 / 1=23(nS), that is, the turn-on time of Q3 is 23nS.

[0059]

[0060] Table 2

[0061] The charge and discharge module 20 is also used to disconnect the switching power supply 30 from the gate of the NMOS transistor Q3 when the indication voltage is at a low level, and connect the fourth terminal to the gate of the NMOS transistor Q3 to switch the drain of the NMOS transistor Q3 and the source of the NMOS transistor Q3 to a disconnected state.

[0062] Specifically, the switching power supply 30 is disconnected from the gate of the NMOS transistor Q3, and the fourth terminal is connected to the gate of the NMOS transistor Q3. At this time, the capacitor between the gate and the source of the NMOS transistor Q3 is discharged through the charge and discharge module 20, and the voltage difference across the capacitor decreases. When the voltage between the gate and the source of the NMOS transistor Q3 drops below the turn-on threshold, the drain and source of the NMOS transistor Q3 are switched to the disconnected state. The positive power supply and the negative power supply are disconnected, and the load 40 is stopped from being powered.

[0063] Continuing to refer to Table 2, assuming that the maximum DC current of the discharge current is 1A, the capacitance between the gate and source of Q3 is discharged with a current of 1A, Ciss is 4600pF, and the time required for the gate and source levels of Q3 to drop from 12V to 0V is: 4600*12 / 1=55.2 (nS), that is, the Q3 turn-off time is 55.2nS.

[0064] The total time for the NMOS transistor Q3 to be turned on and off is 78.2 nS, corresponding to a maximum switching frequency of 1 / 78.2 = 12.79 (MHz). Figure 1 The maximum switching frequency of the PMOS switch shown is only 6.2kHz. 12790 / 6.2=2063, that is, the switching frequency of the power switch circuit provided by the embodiment of the present application can reach thousands of times the switching frequency of the PMOS switch circuit. At the same time, because the NMOS transistor Q3 is turned on and off for a very short time, its half-conduction time is short, the heat generated is small, and the switching loss of the switch element can be greatly reduced.

[0065] In summary, in the power supply switch circuit provided by the embodiment of the present application, the power supply switch circuit includes an NMOS transistor, a control module, a charge and discharge module, a switch power supply and a load; the control module is used to output an indication voltage to the charge and discharge module; the charge and discharge module is used to turn on the switch power supply and the gate of the NMOS transistor when the indication voltage is high, so as to switch the drain of the NMOS transistor and the source of the NMOS transistor to a conduction state; and is also used to turn on the fourth end and the gate of the NMOS transistor when the indication voltage is low, so as to switch the drain of the NMOS transistor and the source of the NMOS transistor to a disconnected state. By controlling the circuit switching of the conduction with the gate of the NMOS transistor, the switching of the on and off state of the NMOS transistor is realized, thereby realizing the control of the entire circuit switch. Compared with the existing scheme, the NMOS transistor has a higher switching frequency, a shorter half-conduction time, less heat generated, and lower switching loss of the switch element.

[0066] exist Figure 2 Based on the structure of the control module 10, the present application embodiment also provides a possibility, please refer to Figure 3 The control module includes an operational amplifier U1 , a reference voltage unit 102 and a control voltage unit 101 .

[0067] The control voltage unit 101 is connected to the non-inverting input terminal of the operational amplifier U1 , the reference voltage unit 102 is connected to the inverting input terminal of the operational amplifier U1 , and the output terminal of the operational amplifier U1 is connected to the second terminal.

[0068] The control voltage unit 101 is used to output a control voltage to the non-inverting input terminal.

[0069] The reference voltage unit 102 is used to output a reference voltage to the inverting input terminal.

[0070] The operational amplifier U1 is used to output a high-level indication voltage to the second end at the output end when the control voltage is higher than the reference voltage; and is also used to output a low-level indication voltage to the second end at the output end when the control voltage is lower than the reference voltage.

[0071] After amplification by the operational amplifier U1, when the indication voltage is at a high level, the indication voltage is greater than the control voltage, so that even when the control voltage is relatively low, the charge and discharge module 20 can be driven to charge the NMOS transistor Q3.

[0072] Please continue to refer to Figure 3 The positive power supply terminal of the operational amplifier U1 is connected to the switching power supply 30, and the negative power supply terminal of the operational amplifier U1 is connected to the negative power supply electrode and the ground respectively.

[0073] Specifically, when the control voltage is higher than the reference voltage, the indication voltage outputted from the output terminal is equal to the level of the switching power supply 30 .

[0074] Please continue to refer to Figure 3 The control module further includes a first capacitor C1, one end of the first capacitor C1 is connected to the switching power supply 30, and the other end of the first capacitor C1 is connected to the ground.

[0075] The first capacitor C1 is used for power supply, energy storage and filtering for the operational amplifier U1.

[0076] Regarding the structure of the control voltage unit and the reference voltage unit, the embodiment of the present application also provides a possibility, please continue to refer to Figure 3 The control voltage unit 101 includes a first resistor R1 and a second resistor R2, and the reference voltage unit 102 includes a third resistor R3 and a voltage divider M1.

[0077] One end of the first resistor R1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the negative power supply electrode, the in-phase input end is connected between the first resistor R1 and the second resistor R2, and the other end of the first resistor R1 is connected to the control signal input end.

[0078] Specifically, the control voltage is the voltage across the second resistor R2, and the voltage is divided by the first resistor R1 and the second resistor R2.

[0079] One end of the third resistor R3 is connected to one end of the voltage divider M1, the other end of the third resistor R3 is connected to the switching power supply 30, the other end of the voltage divider M1 is connected to the negative power supply, and the inverting input end is connected between the third resistor R3 and the voltage divider M1.

[0080] Specifically, the reference voltage is the voltage across the voltage divider M1 , and the third resistor R3 and the voltage divider M1 divide the voltage.

[0081] Assume that R1=3kR, R2=12kR, and the reference voltage is 2V. When the level of the control signal input exceeds 2.5V, the voltage divided by R2 exceeds 2V, that is, the level of U1's non-inverting input to ground exceeds 2V, that is, U1's non-inverting input level exceeds the inverting input level, and U1 outputs a high-level indication voltage.

[0082] When the control signal level is lower than 2.5V, the voltage across R5 is lower than 2V, that is, the level of U1's non-inverting input terminal to ground is lower than 2V, and U1's non-inverting input level is lower than the inverting input level, and U1 outputs a low-level indication voltage.

[0083] In order to avoid the input oscillation of the control signal input terminal, which may cause the circuit to oscillate. Figure 3The control module also includes a diode D1 and a fourth resistor R4, the anode of the diode D1 is connected to the output end of U1, the cathode of the diode D1 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected between the second resistor R2 and the in-phase input end.

[0084] D1 and R4 are used to achieve hysteresis to prevent U1 output oscillation. Assume that U1 outputs a high level of 12V. Assume that when a small current flows through D1, its forward voltage drops to 0V. Continue to refer to the above example R2 = 12kR. If R4 = 274kR, the voltage of 12V level superimposed on R2 through R4 is 0.5V. When the control signal input level exceeds 2.5V and U1 outputs a high level, the voltage across R2 is 2.5V (2V superimposed on the hysteresis voltage 0.5V). Similarly, when the control signal level drops, only when it is lower than 1.875V, the level across R2 is lower than 2V, and U1 outputs a low level. That is, once U1 outputs a high level, as long as the control signal level is higher than 1.875V, U1 can stably output a high level, which can effectively prevent circuit oscillation.

[0085] When the control level is high, D1 prevents the current from flowing from the control signal through R1 and R4 to mistakenly turn on the charge and discharge module 20, and then mistakenly turn on the NMOS transistor Q3, that is, D1 plays a role in preventing mistaken turn-on.

[0086] U1 in the embodiment of the present application can be a common operational amplifier, a rail-to-rail operational amplifier, or an operational amplifier with an internal reference. U1 can be a common comparator, a rail-to-rail comparator, or a comparator with an internal reference.

[0087] Furthermore, the voltage divider M1 is a voltage regulator tube, a fifth resistor or an equal voltage reference IC.

[0088] In order to protect the operational amplifier, the present application embodiment also proposes a possible implementation method, please continue to refer to Figure 3 , the control module also includes a sixth resistor R6.

[0089] One end of the sixth resistor R6 is connected to the output end, and the other end of the sixth resistor R6 is connected to the second end.

[0090] The sixth resistor R6 is used to prevent the operational amplifier U1 from outputting an excessive current to avoid circuit damage.

[0091] Regarding the structure of the charging and discharging module, the present application embodiment also provides a possible implementation method, please refer to Figure 4The charge and discharge module 20 includes a first transistor Q1 and a second transistor Q2, the first transistor Q1 is an NPN transistor, the second transistor Q2 is a PNP transistor, the first end is the collector of the first transistor Q1, the fourth end is the collector of the second transistor Q2, the base of the first transistor Q1 and the base of the second transistor Q2 are both connected to the second end, and the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are both connected to the third end.

[0092] When the indication voltage is at a high level, the first transistor Q1 is turned on, the second transistor Q2 is turned off, and the switch power supply 30 is connected to the gate of the NMOS transistor. When the indication voltage is at a low level, the first transistor Q1 is turned off, the second transistor Q2 is turned on, and the collector of the second transistor Q2 is connected to the gate of the NMOS transistor.

[0093] Possibly, Q1 and Q2 can also be Darlington transistors.

[0094] An embodiment of the present application further provides an electrical device, which includes the above-mentioned power supply switch circuit.

[0095] It should be noted that the electrical equipment provided in this embodiment can achieve the technical effect of the power supply switch circuit. For the sake of brief description, for the parts not mentioned in this embodiment, reference can be made to the corresponding contents in the above embodiments.

[0096] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. 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.

[0097] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A power supply switch circuit, characterized in that: The power supply switch circuit includes an NMOS transistor, a control module, a charge and discharge module, a switch power supply and a load, wherein the positive electrode of the load is connected to the positive electrode of the power supply, the negative electrode of the load is connected to the drain of the NMOS transistor, and the source of the NMOS transistor is connected to the negative electrode of the power supply; The charging and discharging module comprises a first end, a second end, a third end and a fourth end, wherein the first end is connected to the switching power supply, the second end is connected to the control module, the third end is connected to the gate of the NMOS transistor, and the fourth end is connected to the negative power supply electrode; The control module is used to output an indication voltage to the charge and discharge module; The charging and discharging module is used to connect the switching power supply and the gate of the NMOS transistor when the indication voltage is at a high level, and disconnect the fourth terminal from the gate of the NMOS transistor to switch the drain of the NMOS transistor and the source of the NMOS transistor to a conducting state; The charging and discharging module is further used to disconnect the switching power supply from the gate of the NMOS transistor when the indication voltage is at a low level, and connect the fourth terminal to the gate of the NMOS transistor to switch the drain of the NMOS transistor and the source of the NMOS transistor to a disconnected state; The control module includes an operational amplifier, a reference voltage unit and a control voltage unit, wherein the control voltage unit is connected to the non-inverting input terminal of the operational amplifier, the reference voltage unit is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the second terminal; The control voltage unit is used to output a control voltage to the in-phase input terminal; The reference voltage unit is used to output a reference voltage to the inverting input terminal; The operational amplifier is used for, when the control voltage is higher than the reference voltage, the output end outputs a high level indication voltage to the second end; and is also used for, when the control voltage is lower than the reference voltage, the output end outputs a low level indication voltage to the second end; The charge and discharge module includes a first transistor and a second transistor, the first transistor is an NPN transistor, the second transistor is a PNP transistor, the first end is the collector of the first transistor, the fourth end is the collector of the second transistor, the base of the first transistor and the base of the second transistor are both connected to the second end, and the emitter of the first transistor and the emitter of the second transistor are both connected to the third end.

2. The power switch circuit according to claim 1, characterized in that: The positive power supply terminal of the operational amplifier is connected to the switching power supply, and the negative power supply terminal of the operational amplifier is connected to the negative power supply electrode and the ground respectively.

3. The power switch circuit according to claim 2, characterized in that: The control module further includes a first capacitor, one end of which is connected to the switch power supply, and the other end of which is connected to the ground.

4. The power switch circuit according to claim 1, characterized in that: The control voltage unit includes a first resistor and a second resistor, and the reference voltage unit includes a third resistor and a voltage divider; One end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to the negative power supply electrode, the in-phase input end is connected between the first resistor and the second resistor, and the other end of the first resistor is connected to the control signal input end; One end of the third resistor is connected to one end of the voltage divider, the other end of the third resistor is connected to the switching power supply, the other end of the voltage divider is connected to the negative power supply electrode, and the inverting input end is connected between the third resistor and the voltage divider.

5. The power switch circuit according to claim 4, characterized in that: The control module also includes a diode and a fourth resistor, wherein the anode of the diode is connected to the output end, the cathode of the diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected between the second resistor and the in-phase input end.

6. The power switch circuit according to claim 4, characterized in that: The voltage divider is a voltage regulator tube, a fifth resistor or an equal voltage reference IC.

7. The power switch circuit according to claim 1, characterized in that: The control module further includes a sixth resistor, one end of the sixth resistor is connected to the output end, and the other end of the sixth resistor is connected to the second end.

8. An electrical device, characterized in that: The electrical equipment comprises the power supply switch circuit according to any one of claims 1 to 7.

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