Power switch circuit

Abstract

The utility model discloses a power switch circuit, comprising a voltage dividing unit used for generating a divided voltage based on a power supply voltage; the control unit comprises a first transistor and a first capacitor, and the first transistor is used for controlling opening and closing of the first transistor based on the divided voltage so as to generate control voltage at the second end of the first transistor; the first switch unit is used for controlling on and off of the first switch unit based on the control voltage; the second switch unit comprises a second transistor, the control end of the second transistor receives the control voltage, the first end is connected with the reference voltage, the second end is connected with the voltage dividing unit, and the second switch unit is used for controlling the second transistor to be turned on and turned off based on the control voltage so as to adjust the divided voltage and further control the first transistor to be turned on and turned off. The first end of the second capacitor is connected with the second end of the first transistor and the control end of the second transistor, and the second end is connected with reference voltage. According to the utility model, false triggering in the slow power-on and slow power-off processes of the power supply voltage can be avoided, and LED flicker in a post-stage circuit is avoided.

Description

TECHNICAL FIELD

[0001] The utility model belongs to integrated circuit technical field, and specifically relates to a power switch circuit. BACKGROUND

[0002] The power switch circuit is part of a vehicle lamp control circuit, is connected between a vehicle body power supply and a rear-stage DC-DC circuit, and is used for controlling whether the vehicle body power supply supplies power to the rear-stage DC-DC circuit. The existing power switch circuit is prone to instantaneous false triggering (including false power-off or false power-on) in the slow power-on and slow power-off process, causing the LED in the rear-stage DC-DC circuit to flicker.

[0003] Therefore, in view of the above technical problems, it is necessary to provide a power switch circuit. SUMMARY

[0004] The utility model discloses a power switch circuit, can avoid the false triggering in the slow power-on and slow power-off process of power voltage, avoid the LED in the rear-stage circuit flicker.

[0005] In order to realize the above-mentioned purpose, the technical scheme provided by a specific embodiment of the utility model is as follows:

[0006] A power switch circuit, comprising:

[0007] A voltage dividing unit connected between a power voltage and a reference voltage, for generating a voltage dividing voltage based on the power voltage;

[0008] A control unit comprising a first transistor and a first capacitor, a first end of the first transistor being connected with the reference voltage, a control end being connected with a first end of the first capacitor and the voltage dividing unit and receiving the voltage dividing voltage, a second end of the first capacitor being connected with the reference voltage, the first transistor being used for controlling its own turn-on and turn-off based on the voltage dividing voltage to generate a control voltage at a second end of the first transistor;

[0009] A first switch unit connected between the power voltage and an output node and connected with the second end of the first transistor, for controlling its own turn-on and turn-off based on the control voltage;

[0010] A second switch unit comprising a second transistor and a second capacitor, a control end of the second transistor being connected with the second end of the first transistor and receiving the control voltage, a first end being connected with the reference voltage, and a second end being connected with the voltage dividing unit, the second transistor being used for controlling its own turn-on and turn-off based on the control voltage to adjust the voltage dividing voltage, and further control the turn-on and turn-off of the first transistor, a first end of the second capacitor being connected with the second end of the first transistor and the control end of the second transistor, and a second end being connected with the reference voltage.

[0011] In one or more embodiments of the utility model, when the power voltage is greater than or equal to the first voltage threshold, the first transistor is turned on, and the first switch unit controls itself to be turned on based on the control voltage;

[0012] When the power voltage is less than or equal to the second voltage threshold, the first transistor is turned off, and the first switch unit controls itself to be turned off based on the control voltage;

[0013] When the power voltage changes from the first voltage threshold to the second voltage threshold, the second transistor changes from the off state to the on state to pull down the voltage, the first transistor is turned off, and the first switch unit controls itself to be turned off based on the control voltage;

[0014] When the power voltage changes from the second voltage threshold to the first voltage threshold, the second transistor changes from the on state to the off state to pull up the voltage, the first transistor is turned on, and the first switch unit controls itself to be turned on based on the control voltage.

[0015] In one or more embodiments of the utility model, the voltage dividing unit includes a first resistor, a second resistor and a third resistor, the first end of the first resistor is connected with the power voltage, the second end is connected with the first end of the second resistor and the control end of the first transistor and generates a voltage, the second end of the second resistor is connected with the first end of the third resistor and the second end of the second transistor, and the second end of the third resistor is connected with the reference voltage.

[0016] In one or more embodiments of the utility model, the first switch unit includes a third transistor, the first end of the third transistor is connected with the power voltage, the control end is connected with the second end of the first transistor and receives the control voltage, and the second end is connected with the output node.

[0017] In one or more embodiments of the utility model, the first switch unit further includes a first voltage stabilizing unit, the first voltage stabilizing unit includes a third capacitor, a fourth resistor, a fifth resistor and a first diode, the first end of the third capacitor, the first end of the fourth resistor and the cathode of the first diode are connected with the power voltage and the first end of the third transistor, the second end of the third capacitor, the second end of the fourth resistor and the anode of the first diode are connected with the first end of the fifth resistor and the control end of the third transistor, and the second end of the fifth resistor is connected with the second end of the first transistor.

[0018] In one or more embodiments of the utility model, the power switch circuit further includes a first anti-reverse flow device, the first end of the first anti-reverse flow device receives the power voltage, and the second end is connected with the first end of the first transistor and the first voltage stabilizing unit.

[0019] In one or more embodiments of the utility model, the power switch circuit further includes a second voltage stabilizing unit, the second voltage stabilizing unit includes a third diode, the cathode of the third diode receives the power supply voltage, and the anode is connected with the voltage dividing unit;And / or, the power switch circuit further includes a second anti -reverse flow device, the first end of the second anti -reverse flow device receives the power supply voltage, and the second end is connected with the voltage dividing unit.

[0020] In one or more embodiments of the utility model, the power switch circuit further includes a fourth capacitor, the first end of the fourth capacitor is connected with the output node and the first switch unit, and the second end is connected with the reference voltage.

[0021] In one or more embodiments of the utility model, the first transistor includes an N-channel bipolar transistor;And / or, the second transistor includes an N-channel MOS tube.

[0022] Compared with the prior art, the power switch circuit of the utility model, through the control unit generates the control voltage for controlling the second switch unit, and the second switch unit controls the opening and closing of itself based on the control voltage to adjust the voltage dividing voltage, and then realizes the feedback control to the control unit, avoids the first switch unit being mis-triggered in the slow power-on and slow power-off process of the power supply voltage, and effectively suppresses the LED flicker in the later stage circuit. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments in the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creating creative labor.

[0024] Figure 1 It is the system block diagram of the power switch circuit in the utility model;

[0025] Figure 2 It is the circuit principle diagram of the power switch circuit in the embodiment 1 of the utility model;

[0026] Main drawing mark:

[0027] 10-voltage dividing unit, 20-control unit, 30-first switch unit, 31-first voltage stabilizing unit, 40-second switch unit. DETAILED DESCRIPTION

[0028] In order to make the technical scheme in the present application better understood by those skilled in the art, the technical scheme in the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0029] Unless otherwise clearly indicated, in the specification and claims of the application, the term "comprise" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements.

[0030] In the specification, "coupling" or "connection" or "linked" includes both direct connection and indirect connection. Indirect connection is the connection through an intermediate medium, such as the connection through an electrically conductive medium, which can have parasitic inductance or parasitic capacitance; indirect connection can also include the connection through other active devices or passive devices on the basis of achieving the same or similar functional purposes, such as the connection through circuits or components such as switches, follower circuits, etc. In addition, in the present application, words such as "first", "second" and the like are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply a certain actual relationship, quantity or order between the technical features.

[0031] In the detailed description of the specification, reference is made to the drawings forming a part thereof, in which the same reference numerals are always used to represent the same parts and in which by way of example only, an exemplary embodiment is shown. It is to be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope of the present application. Therefore, the following detailed description is not to be taken in a limiting sense.

[0032] Various operations can be described as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order-dependent. Specifically, these operations can not be performed in the order of presentation. Operations described can be performed in a different order than the described embodiment. Various additional operations can be performed and / or described operations can be omitted in additional embodiments.

[0033] For the purposes of the present application, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of the present application, the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0034] Various components, devices, etc. can be referred to or shown herein in singular form (e.g., "a MOS transistor," "a transistor," "a switch," etc.), but this is merely for convenience and any element referred to in singular form can include a plurality of such elements unless the content clearly dictates otherwise.

[0035] The description uses the phrases "in this embodiment" or "in other embodiments" or "in some embodiments," which can each refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "containing," "having," and the like, as used with respect to an embodiment of the present application, are synonymous.

[0036] As Figure 1 shown, the power switch circuit of the utility model, including:

[0037] The voltage dividing unit 10 is connected between the power supply voltage VBAT and the reference voltage GND, and is used to generate a voltage dividing voltage V1 based on the power supply voltage VBAT;

[0038] The control unit 20 includes a first transistor Q1 and a first capacitor C1. The first end of the first transistor Q1 is connected to the reference voltage GND. The control end is connected to the first end of the first capacitor C1 and the voltage dividing unit 10 and receives the voltage dividing voltage V1. The second end of the first capacitor C1 is connected to the reference voltage GND. The first transistor Q1 is used to control its own opening and closing based on the voltage dividing voltage V1 to generate a control voltage V2 at the second end of the first transistor Q1.

[0039] The first switch unit 30 is connected between the power supply voltage VBAT and the output node P1, and is connected to the second end of the first transistor Q1, and is used to control its own opening and closing based on the control voltage V2.

[0040] The second switch unit 40 includes a second transistor Q2 and a second capacitor C2. The control end of the second transistor Q2 is connected to the second end of the first transistor Q1 and receives the control voltage V2. The first end is connected to the reference voltage GND. The second end is connected to the voltage dividing unit 10. The second transistor Q2 is used to control its own opening and closing based on the control voltage V2 to adjust the voltage dividing voltage V1, and in turn control the opening and closing of the first transistor Q1. The first end of the second capacitor C2 is connected to the second end of the first transistor Q1 and the control end of the second transistor Q2. The second end is connected to the reference voltage GND.

[0041] The output node P1 is connected to the subsequent DC-DC circuit, wherein the DC-DC circuit includes an LED. The power switch circuit of the utility model is used to control the power supply voltage VBAT to power the subsequent DC-DC circuit, so as to avoid the LED in the subsequent circuit from flickering with simple circuit design.

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] Example 1:

[0044] like Figure 2 As shown, a power switch circuit in this embodiment includes a voltage divider unit 10, a control unit 20, a first switch unit 30, and a second switch unit 40.

[0045] Voltage divider unit 10 is connected between power supply voltage VBAT and reference voltage GND, and is used to generate voltage divider voltage V1 based on power supply voltage VBAT.

[0046] The control unit 20 includes a first transistor Q1 and a first capacitor C1. The first terminal of the first transistor Q1 is connected to a reference voltage GND. The control terminal is connected to the first terminal of the first capacitor C1 and the voltage divider unit 10, and receives the divided voltage V1. The second terminal of the first capacitor C1 is connected to the reference voltage GND. The first transistor Q1 is used to control its own on / off state based on the divided voltage V1 to generate a control voltage V2 at its second terminal. In this embodiment, the first transistor Q1 is an N-channel bipolar transistor. The first terminal of the first transistor Q1 is the emitter, the second terminal is the collector, and the control terminal is the base.

[0047] The first switching unit 30 is connected between the power supply voltage VBAT and the output node P1, and is connected to the second terminal of the first transistor Q1, and is used to control its own turn-on and turn-off based on the control voltage V2.

[0048] The second switching unit 40 includes a second transistor Q2 and a second capacitor C2. The control terminal of the second transistor Q2 is connected to the second terminal of the first transistor Q1 and receives a control voltage V2. The first terminal of the second transistor Q2 is connected to a reference voltage GND, and the second terminal is connected to a voltage divider unit 10. The second transistor Q2 is used to control its own on / off state based on the control voltage V2 to adjust the voltage divider voltage V1, thereby controlling the on / off state of the first transistor Q1. The first terminal of the second capacitor C2 is connected to the second terminal of the first transistor Q1 and the control terminal of the second transistor Q2, and the second terminal is connected to the reference voltage GND. In this embodiment, the second transistor Q2 is an N-channel MOSFET. The first terminal of the second transistor Q2 is the source, the second terminal is the drain, and the control terminal is the gate.

[0049] In this embodiment, the charging and discharging speeds of the first capacitor C1 and the second capacitor C2 are used to adjust the turn-on and turn-off speeds of the first transistor Q1 and the second transistor Q2.

[0050] When the power supply voltage VBAT is greater than or equal to the first voltage threshold, the first transistor Q1 is turned on, and the first switching unit 30 controls itself to turn on based on the control voltage V2 so that the power supply voltage VBAT supplies power to the output node P1.

[0051] When the power supply voltage VBAT is less than or equal to the second voltage threshold, the first transistor Q1 is turned off, and the first switch unit 30 is controlled to be turned off by the control voltage V2 to stop the power supply voltage VBAT from powering the output node P1.

[0052] When the power supply voltage VBAT changes from the first voltage threshold to the second voltage threshold, the second transistor Q2 changes from the off state to the on state to pull down the voltage V1, the first transistor Q1 is turned off, and the first switch unit 30 is controlled to be turned off by the control voltage V2 to stop the power supply voltage VBAT from powering the output node P1.

[0053] When the power supply voltage VBAT changes from the second voltage threshold to the first voltage threshold, the second transistor Q2 changes from the on state to the off state to pull up the voltage V1, the first transistor Q1 is turned on, and the first switch unit 30 is controlled to be turned on by the control voltage V2 to power the output node P1 by the power supply voltage VBAT.

[0054] The voltage dividing unit 10 in the embodiment includes a first resistor R1, a second resistor R2, and a third resistor R3. The first end of the first resistor R1 is connected to the power supply voltage VBAT, the second end is connected to the first end of the second resistor R2 and the control end of the first transistor Q1 to generate the voltage V1, the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the second end of the second transistor Q2, and the second end of the third resistor R3 is connected to the reference voltage GND.

[0055] The first switch unit 30 includes a third transistor Q3 and a first voltage stabilizing unit 31. The first end of the third transistor Q3 is connected to the power supply voltage VBAT (i.e., the VIN voltage), the control end is connected to the second end of the first transistor Q1 to receive the control voltage V2, and the second end is connected to the output node P1. In the embodiment, the third transistor Q3 includes a P-channel MOS tube, the first end of the third transistor Q3 is the source, the second end is the drain, and the control end is the gate.

[0056] The first voltage stabilizing unit 31 includes a third capacitor C3, a fourth resistor R4, a fifth resistor R5, and a first diode Z1. The first end of the third capacitor C3, the first end of the fourth resistor R4, and the cathode of the first diode are connected to the power supply voltage VBAT and the first end of the third transistor Q3, the second end of the third capacitor C3, the second end of the fourth resistor R4, and the anode of the first diode Z1 are connected to the first end of the fifth resistor R5 and the control end of the third transistor Q3, and the second end of the fifth resistor R5 is connected to the second end of the first transistor Q1. Exemplarily, the first diode Z1 includes a Zener diode.

[0057] The power switch circuit further comprises a first anti-reverse flow device, a first end of the first anti-reverse flow device receiving the power supply voltage VBAT, and a second end of the first anti-reverse flow device being connected with the first end of the first transistor Q1 and the first voltage stabilizing unit 31. Exemplarily, the first anti-reverse flow device comprises a second diode D1, an anode of the second diode D1 receiving the power supply voltage VBAT, and a cathode of the second diode D1 being connected with the first end of the first transistor Q1 and the first voltage stabilizing unit 31. It should be noted that the second diode D1 is connected between the power supply voltage VBAT and the voltage VIN, for preventing the circuit from flowing backward, and the voltage difference between the power supply voltage VBAT and the voltage VIN in the normal working state is only the conduction voltage drop of the second diode D1, wherein the power supply voltage VBAT is supplied by the vehicle body power supply, and the voltage VIN_1 on the output node P1 is used as the power supply of the rear-stage DC-DC circuit.

[0058] Further, the power switch circuit in the embodiment further comprises a second voltage stabilizing unit 50, the second voltage stabilizing unit 50 comprising a third diode Z2, a cathode of the third diode Z2 receiving the power supply voltage VBAT, and an anode of the third diode Z2 being connected with the voltage dividing unit 10. Exemplarily, the third diode Z2 comprises a Zener diode.

[0059] Further, the power switch circuit in the embodiment further comprises a second anti-reverse flow device, a first end of the second anti-reverse flow device receiving the power supply voltage VBAT, and a second end of the second anti-reverse flow device being connected with the voltage dividing unit 10. Exemplarily, the first anti-reverse flow device comprises a fourth diode D2, an anode of the fourth diode D2 receiving the power supply voltage VBAT, and a cathode of the fourth diode D2 being directly or indirectly connected with the voltage dividing unit 10.

[0060] Further, the power switch circuit in the embodiment further comprises a fourth capacitor C4, a first end of the fourth capacitor C4 being connected with the output node P1 and the first switch unit 30, and a second end of the fourth capacitor C4 being connected with the reference voltage GND, and the fourth capacitor C4 is used for filtering.

[0061] The first transistor Q1 comprises an N-channel bipolar transistor, a first end of the first transistor Q1 being a source, a second end of the first transistor Q1 being a drain, and a control end of the first transistor Q1 being a gate.

[0062] The working principle of the utility model is exemplarily explained with the first voltage threshold value being 9V and the second voltage threshold value being 8V:

[0063] When the power supply voltage VBAT is greater than or equal to 9V, at this time, the voltage dividing voltage V1 controls the first transistor Q1 to be turned on, so as to make the first transistor Q1 pull down the control voltage V2 to a low level, and there is a voltage difference between the gate and the drain of the third transistor Q3 to make the third transistor Q3 be turned on, and the third transistor Q3 is turned on to make the power supply voltage VBAT supply power to the output node P1, and at this time, the second transistor Q2 keeps itself off based on the control voltage V2.

[0064] When the power supply voltage VBAT is less than or equal to 8V, the first transistor Q1 is turned off at this time by the voltage V1, so that the control voltage V2 is pulled up, there is no voltage difference between the gate and the drain of the third transistor Q3, the third transistor Q3 is turned off to stop the power supply voltage VBAT from supplying power to the output node P1.

[0065] When the power supply voltage VBAT slowly changes from 9V to 8V, the first transistor Q1 successively experiences saturation, amplification, and cut-off states: when the first transistor Q1 is in the saturation state, the voltage V1 obtained by voltage division of the series resistance values of the first resistor R1, the second resistor R2, and the third resistor R3 is between about 0.6-0.7V, the control voltage V2 is less than 0.2V, at this time, the control voltage V2 does not satisfy the opening threshold of the second transistor Q2, and the second transistor Q2 remains turned off. As the power supply voltage VBAT continues to drop, the first transistor Q1 is in the amplification zone, and the first transistor Q1 cannot completely open and pull up the control voltage V2 to about 2V, and then the second transistor Q2 opens and shorts the third resistor R3, so as to achieve adjustment of the voltage V1, the voltage V1 is reduced to below 0.6V, the first transistor Q1 is turned off, the first transistor Q1 skips the 0.1V amplification zone and directly enters the cut-off state, and the third transistor Q3 is thus turned off, so that the power supply voltage VBAT stops supplying power to the output node P1, avoiding the misopening of the third transistor Q3 in the power-off process, effectively suppressing the transient current generated by the output node P1 jitter, and avoiding the flickering of the LED in the subsequent circuit.

[0066] When the power supply voltage VBAT slowly changes from 8V to 9V, the first transistor Q1 successively experiences cut-off, amplification, and saturation states: when the first transistor Q1 is in the cut-off state, the control voltage V2 is equal to the VIN voltage, the second transistor Q2 is in the open state, and the voltage V1 is obtained by voltage division of the first resistor R1 and the second resistor R2. As the power supply voltage VBAT continues to rise, the first transistor Q1 is in the amplification zone, the control voltage V2 is gradually pulled down to less than 2V, the second transistor Q2 is turned off, the voltage V1 is obtained by voltage division of the series resistance values of the first resistor R1, the second resistor R2, and the third resistor R3, the voltage V1 is about 0.7V, the first transistor Q1 skips the 0.1V amplification zone and directly enters the saturation state, and the third transistor Q3 is thus turned on, so that the power supply voltage VBAT starts to supply power to the output node P1, avoiding the misopening of the third transistor Q3 in the power-on process, effectively suppressing the transient current generated by the output node P1 jitter, and avoiding the flickering of the LED in the subsequent circuit.

[0067] It can be understood that the resistance values of the first resistor R1, the second resistor R2, and the third resistor R3, and the capacitance values of the first capacitor C1 and the second capacitor C2 in the embodiment can be adjusted according to the working principle of the utility model, and the embodiment is not limited.

[0068] The utility model has the following beneficial effects:

[0069] The control unit 20 generates a control voltage for controlling the second switch unit 40, and the second switch unit 40 controls its opening and closing based on the control voltage to adjust the divided voltage V1, thereby realizing feedback control of the control unit 20, avoiding the first switch unit 40 from being mis-triggered during slow power-on and slow power-off of the power supply voltage, and effectively suppressing LED flicker in the subsequent circuit.

[0070] It is apparent for those skilled in the art that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or basic characteristics of the utility model. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the utility model is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims should be included in the utility model. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0071] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A power switching circuit, characterized by, The application relates to a voltage regulator. The voltage regulator comprises: a voltage dividing unit connected between a power supply voltage and a reference voltage, for generating a voltage dividing voltage based on the power supply voltage; a control unit comprising a first transistor and a first capacitor, a first end of the first transistor being connected to the reference voltage, a control end being connected to a first end of the first capacitor and the voltage dividing unit and receiving the voltage dividing voltage, a second end of the first capacitor being connected to the reference voltage, the first transistor being used for controlling its opening and closing based on the voltage dividing voltage to generate a control voltage at a second end of the first transistor; a first switch unit connected between the power supply voltage and an output node and connected to the second end of the first transistor, for controlling its opening and closing based on the control voltage; and a second switch unit comprising a second transistor and a second capacitor, a control end of the second transistor being connected to the second end of the first transistor and receiving the control voltage, a first end being connected to the reference voltage, and a second end being connected to the voltage dividing unit, the second transistor being used for controlling its opening and closing based on the control voltage to adjust the voltage dividing voltage and further control the opening and closing of the first transistor, a first end of the second capacitor being connected to the second end of the first transistor and the control end of the second transistor, and a second end being connected to the reference voltage. When the power supply voltage is greater than or equal to a first voltage threshold, the first transistor is opened, and the first switch unit is controlled to be opened based on the control voltage. When the power supply voltage is less than or equal to a second voltage threshold, the first transistor is closed, and the first switch unit is controlled to be closed based on the control voltage. When the power supply voltage changes from the first voltage threshold to the second voltage threshold, the second transistor changes from a closed state to an opened state to pull down the voltage dividing voltage, the first transistor is closed, and the first switch unit is controlled to be closed based on the control voltage.

2. The power switch circuit of claim 1, wherein, When the power supply voltage changes from the second voltage threshold to the first voltage threshold, the second transistor changes from an opened state to a closed state to pull up the voltage dividing voltage, the first transistor is opened, and the first switch unit is controlled to be opened based on the control voltage. The voltage dividing unit comprises a first resistor, a second resistor and a third resistor, a first end of the first resistor being connected to the power supply voltage, a second end being connected to a first end of the second resistor and a control end of the first transistor and generating the voltage dividing voltage, a second end of the second resistor being connected to a first end of the third resistor and a second end of the second transistor, and a second end of the third resistor being connected to the reference voltage. The first switch unit comprises a third transistor, a first end of the third transistor being connected to the power supply voltage, a control end being connected to the second end of the first transistor and receiving the control voltage, and a second end being connected to the output node. ​ 3. The power switch circuit of claim 1, wherein, ​ 4. The power switch circuit of claim 1, wherein, ​ 5. The power switch circuit of claim 4, wherein, The first switch unit further comprises a first voltage stabilizing unit, the first voltage stabilizing unit comprising a third capacitor, a fourth resistor, a fifth resistor and a first diode, a first end of the third capacitor, a first end of the fourth resistor and a cathode of the first diode being connected to a power supply voltage and a first end of the third transistor, a second end of the third capacitor, a second end of the fourth resistor and an anode of the first diode being connected to a first end of the fifth resistor and a control end of the third transistor, a second end of the fifth resistor being connected to a second end of the first transistor.

6. The power switch circuit of claim 1, wherein, The power switch circuit further comprises a first anti-reverse flow device, a first end of the first anti-reverse flow device receiving the power supply voltage, a second end being connected to the first end of the first transistor and the first voltage stabilizing unit.

7. The power switch circuit of claim 1, wherein, The power switch circuit further comprises a second voltage stabilizing unit, the second voltage stabilizing unit comprising a third diode, a cathode of the third diode receiving the power supply voltage, an anode being connected to the voltage dividing unit; and / or, The power switch circuit further comprises a second anti-reverse flow device, a first end of the second anti-reverse flow device receiving the power supply voltage, a second end being connected to the voltage dividing unit.

8. The power switch circuit of claim 1, wherein, The power switch circuit further comprises a fourth capacitor, a first end of the fourth capacitor being connected to the output node and the first switch unit, a second end being connected to a reference voltage.

9. The power switch circuit of claim 1, wherein, The first transistor comprises an N-channel bipolar transistor; and / or, The second transistor comprises an N-channel MOS transistor.

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