Switching circuit and power supply circuit

Abstract

The utility model relates to a switching circuit and a power supply circuit. The switching circuit is applied to a power supply circuit and comprises a hysteresis circuit, a power supply monitoring module and a switching control circuit, the input end of the hysteresis circuit is used for being connected with a power supply, the input end of the power supply monitoring module is connected with the output end of the hysteresis circuit, and the first input end of the switching control circuit is used for being connected with the power supply. The second input end of the switch control circuit is connected with the output end of the power supply monitoring module, and the output end of the switch control circuit is used for being connected with a load. According to the technical scheme provided by the invention, safe startup and shutdown of the HMI product can be realized.

Description

Technical Field

[0001] The present application relates to the field of power supply control technology, and in particular to a switching circuit and a power supply circuit. Background Art

[0002] With increasing market demand, the number of HMI (Human Machine Interface) products is increasing. These products must cope with complex operating conditions and meet users' growing requirements for data preservation, smooth plug-in operation, and seamless switching. Furthermore, the CPU (Central Processing Unit) systems in HMI products are steadily improving, and operating systems are being gradually optimized and upgraded, which in turn increases the hardware performance requirements for HMI products.

[0003] Currently, SOC (System on Chip) has increasingly stringent requirements for the safety of the entire machine power supply. Therefore, it is urgent to propose a solution that can achieve safe power on and off of HMI products. Utility Model Content

[0004] Based on this, an embodiment of the present application provides a switching circuit and a power supply circuit that can realize the safe power on and off of HMI products.

[0005] In a first aspect, the present application provides a switching circuit. The switching circuit comprises:

[0006] a hysteresis circuit, wherein an input end of the hysteresis circuit is connected to a power supply;

[0007] a power monitoring module, wherein an input end of the power monitoring module is connected to an output end of the hysteresis circuit;

[0008] a switch control circuit, wherein a first input terminal of the switch control circuit is connected to the power supply, a second input terminal of the switch control circuit is connected to the output terminal of the power monitoring module, and an output terminal of the switch control circuit is connected to a load;

[0009] During the power-on process, the hysteresis circuit is configured to switch to a conductive state when the power supply voltage of the power supply reaches a power-on voltage threshold, the power monitoring module is configured to output a first level signal when the voltage input to the hysteresis circuit reaches a monitoring voltage threshold, and the switch control circuit is configured to switch to a conductive state when the first level signal is detected;

[0010] During the power-off process, the hysteresis circuit is used to switch to an open circuit state when the power supply voltage drops to a power-off voltage threshold, the power supply monitoring module is used to output a second level signal when the voltage input to the hysteresis circuit drops to the monitoring voltage threshold, and the switch control circuit is used to switch to an off state when the second level signal is detected.

[0011] In one embodiment, the switch control circuit includes:

[0012] a first control circuit connected to an output terminal of the power monitoring module;

[0013] a second control circuit, the second control circuit being connected to the power supply and the second control circuit being connected to the first control circuit;

[0014] a third control circuit, the third control circuit being connected to the power supply and the third control circuit being connected to the second control circuit;

[0015] A switch module is connected to the third control circuit, is further connected to the power supply, and is used to connect to the load.

[0016] In one embodiment, the first control circuit includes:

[0017] a first voltage-dividing resistor, wherein a first end of the first voltage-dividing resistor is connected to an output end of the power monitoring module;

[0018] a second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor is connected to a second end of the first voltage-dividing resistor, and a second end of the second voltage-dividing resistor is grounded;

[0019] A first transistor, wherein the base of the first transistor is connected between the first voltage-dividing resistor and the second voltage-dividing resistor, the collector of the first transistor is connected to the second control circuit, and the emitter of the first transistor is grounded.

[0020] In one embodiment, the first control circuit further includes:

[0021] A first filter capacitor is connected in parallel with the second voltage-dividing resistor.

[0022] In one embodiment, the second control circuit includes:

[0023] a third voltage-dividing resistor, wherein a first end of the third voltage-dividing resistor is used to be connected to the power supply, and a second end of the third voltage-dividing resistor is connected to the collector of the first transistor;

[0024] a fourth voltage-dividing resistor, wherein a first end of the fourth voltage-dividing resistor is connected to the second end of the third voltage-dividing resistor, and a second end of the fourth voltage-dividing resistor is grounded;

[0025] A second triode, wherein the base of the second triode is connected between the third voltage-dividing resistor and the fourth voltage-dividing resistor, the collector of the second triode is connected to the third control circuit, and the emitter of the second triode is grounded.

[0026] In one embodiment, the second control circuit further includes:

[0027] A second filter capacitor is connected in parallel with the fourth voltage-dividing resistor.

[0028] In one embodiment, the third control circuit includes:

[0029] a fifth voltage-dividing resistor, wherein a first end of the fifth voltage-dividing resistor is used to be connected to the power supply, and a second end of the fifth voltage-dividing resistor is connected to the collector of the second transistor;

[0030] a sixth voltage-dividing resistor, a first end of the sixth voltage-dividing resistor being connected to the second end of the fifth voltage-dividing resistor;

[0031] a pull-down resistor, wherein a first end of the pull-down resistor is connected to the second end of the sixth voltage-dividing resistor, a second end of the pull-down resistor is grounded, and the switch module is connected between the sixth voltage-dividing resistor and the pull-down resistor;

[0032] A first energy storage capacitor is connected in parallel with the pull-down resistor.

[0033] In one embodiment, the switch module includes:

[0034] a seventh voltage-dividing resistor, wherein a first end of the seventh voltage-dividing resistor is configured to be connected to the power supply;

[0035] an eighth voltage-dividing resistor, a first end of the eighth voltage-dividing resistor being connected to the second end of the seventh voltage-dividing resistor;

[0036] a first MOS switch tube, wherein a control electrode of the first MOS switch tube is connected between the sixth voltage-dividing resistor and the pull-down resistor, a first electrode of the first MOS switch tube is connected to the second end of the eighth voltage-dividing resistor, and a second electrode of the first MOS switch tube is grounded;

[0037] a second MOS switch tube, wherein the control electrode of the second MOS switch tube is connected between the seventh voltage-dividing resistor and the eighth voltage-dividing resistor, the first electrode of the second MOS switch tube is connected to the power supply, and the second electrode of the second MOS switch tube is used to be connected to the load.

[0038] In one embodiment, the switch module further includes:

[0039] A third filter capacitor is connected in parallel with the seventh voltage-dividing resistor.

[0040] In one embodiment, the switch control circuit further includes:

[0041] A second energy storage capacitor, wherein a first electrode of the second energy storage capacitor is connected to a second electrode of the second MOS switch tube, and a first electrode of the second energy storage capacitor is connected to a second electrode of the first MOS switch tube.

[0042] In one embodiment, the hysteresis circuit includes:

[0043] a first voltage divider circuit, wherein a first end of the first voltage divider circuit is used to be connected to the power supply, and a second end of the first voltage divider circuit is grounded;

[0044] a voltage reference source, wherein a reference voltage terminal of the voltage reference source is connected to a voltage dividing point of the first voltage dividing circuit, and a ground terminal of the voltage reference source is grounded;

[0045] a second voltage divider circuit, wherein a first end of the second voltage divider circuit is used to be connected to the power supply, and a second end of the second voltage divider circuit is connected to an enable end of the voltage reference source and a voltage dividing point of the first voltage divider circuit;

[0046] a third triode, wherein the base of the third triode is connected to the voltage dividing point of the second voltage dividing circuit, and the emitter of the third triode is used to be connected to the power supply;

[0047] A first parallel resistor and a second parallel resistor, wherein the first end of the first parallel resistor is connected to the second end of the second voltage divider circuit, the first end of the second parallel resistor is grounded, and the collector of the third transistor, the second end of the first parallel resistor and the second end of the second parallel resistor are all connected to the output end of the hysteresis circuit.

[0048] In one embodiment, the hysteresis circuit further includes:

[0049] a current-limiting resistor, wherein a first end of the current-limiting resistor is connected to a voltage dividing point of the second voltage-dividing circuit, and a second end of the current-limiting resistor is connected to a base of the third transistor.

[0050] In one embodiment, the switch circuit further includes:

[0051] An energy storage circuit, wherein the input end of the energy storage circuit is used to be connected to the power supply, and the output end of the energy storage circuit is grounded.

[0052] In a second aspect, the present application provides a power supply circuit, comprising a power supply and a switch circuit as described in any one of the first aspects above, wherein the power supply is connected to the switch circuit.

[0053] The above-mentioned switching circuit and power supply circuit, the switching circuit includes a hysteresis circuit, a power supply monitoring module and a switching control circuit, the input end of the hysteresis circuit is used to connect to the power supply, the input end of the power supply monitoring module is connected to the output end of the hysteresis circuit, the first input end of the switching control circuit is used to connect to the power supply, the second input end of the switching control circuit is connected to the output end of the power supply monitoring module, and the output end of the switching control circuit is used to connect to the load. During the power-on process, the hysteresis circuit switches to the on state only when the power supply voltage reaches the power-on voltage threshold, and inputs a voltage signal to the power supply monitoring module. The power supply monitoring module outputs a first level signal when the voltage input to the hysteresis circuit reaches the monitoring voltage threshold. The switching control circuit switches to the on state when detecting the first level signal. After the switching control circuit is turned on, the load is powered on. During the power-off process, the hysteresis circuit switches to the open state only when the power supply voltage drops to the power-off voltage threshold, and stops inputting the voltage signal to the power supply monitoring module. The visual module outputs a second level signal when the voltage input to the hysteresis circuit drops to a monitoring voltage threshold, and the switch control circuit switches to the off state only when it detects the second level signal. In this way, the power supply voltage is compared with the power-on voltage threshold and the power-off voltage threshold through the hysteresis circuit. The hysteresis circuit is turned on only when the power supply voltage reaches the power-on voltage threshold, and the subsequent-stage circuit is turned on only when the voltage of the subsequent-stage input to the hysteresis circuit reaches the monitoring voltage threshold. During power-off, the hysteresis circuit is disconnected only when the power supply voltage drops to the power-off voltage threshold. The power supply monitoring module and the switch control circuit are powered off only when the power supply monitoring module detects that the input voltage has dropped to the monitoring voltage threshold. In this way, when the switch circuit provided in the embodiment of the present application is used in an HMI product, it can avoid the problem of repeated power on and off of the subsequent-stage circuit in a short period of time due to voltage fluctuations of the power supply voltage, which may cause abnormal power on and off of the HMI product and damage to the software and hardware. The embodiment of the present application can achieve safe power on and off of the HMI product. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0055] Figure 1 A schematic diagram of a switching circuit provided in an embodiment of the present application;

[0056] Figure 2 A schematic diagram of a hysteresis circuit provided in an embodiment of the present application;

[0057] Figure 3 A schematic diagram of a hysteresis circuit and a switch control circuit provided in an embodiment of the present application;

[0058] Figure 4 A schematic diagram of a switch control circuit provided in an embodiment of the present application;

[0059] Figure 5 A schematic diagram of an energy storage circuit provided in an embodiment of the present application.

[0060] Description of reference numerals:

[0061] Hysteresis circuit 100; first voltage divider circuit 101; second voltage divider circuit 102; power monitoring module 200; switch control circuit 300; first control circuit 301; second control circuit 302; third control circuit 303; switch module 304; energy storage circuit 400. DETAILED DESCRIPTION

[0062] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0064] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0065] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0066] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0067] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0068] With increasing market demand, the number of HMI (Human Machine Interface) products is increasing. These products must cope with complex operating conditions and meet users' growing requirements for data preservation, smooth plug-in operation, and seamless switching. Furthermore, the CPU (Central Processing Unit) systems in HMI products are steadily improving, and operating systems are being gradually optimized and upgraded, which in turn increases the hardware performance requirements for HMI products.

[0069] For example, the stability of the SOC (System on Chip) and PMIC (Power Management Integrated Circuit) is required to be high, and the safety requirements for the power supply of the entire machine are becoming increasingly stringent. Therefore, it is urgent to propose a solution that can achieve safe power on and off of HMI products.

[0070] To solve the above technical problems, the embodiments of the present application provide a switch circuit and a power supply circuit. The following, in conjunction with the figures, exemplarily introduces the technical solutions and beneficial effects provided by the embodiments of the present application.

[0071] See Figure 1 , provides a switching circuit, which can be set in an HMI product, and of course can also be set in other products with a built-in power supply and that need to achieve safe power on and off. The application environment of the switching circuit of the embodiment of the present application is not limited here. The following embodiments are all explained by taking the switching circuit set in the HMI product as an example.

[0072] In the embodiment of the present application, the switch circuit includes a hysteresis circuit 100, a power monitoring module 200 and a switch control circuit 300. The input end of the hysteresis circuit 100 is used to connect to the power supply, for example, Figure 1 The VDD_5V1 shown is the 5V internal operating voltage provided by the power supply.

[0073] The output of the hysteresis circuit 100 is connected to the input of the power monitoring module 200. The hysteresis circuit 100 is also called a hysteresis comparator. The hysteresis circuit 100 is used to set the turn-on threshold (power-on voltage threshold) and turn-off threshold (power-off voltage threshold) of the subsequent circuit.

[0074] In an embodiment of the present application, the hysteresis circuit includes a first voltage divider circuit, a voltage reference source, a second voltage divider circuit, a third transistor, a first parallel resistor, and a second parallel resistor.

[0075] For example, see Figure 2 , Figure 2 is a schematic diagram of a hysteresis circuit 100 .

[0076] The first end of the first voltage divider circuit 101 is used to connect to the power supply, and the second end of the first voltage divider circuit 101 is grounded. The first voltage divider circuit 101 includes Figure 2 The resistor R1 and the resistor R2 are shown, the first end of the resistor R1 is used to connect to the power supply, the second end of the resistor R1 is connected to the first end of the resistor R2, and the second end of the resistor R2 is grounded.

[0077] Voltage reference source ( Figure 2 The reference voltage terminal of U1 shown in FIG. 1 (which may be a shunt regulator integrated circuit) (such as Figure 2 Pin 1 as shown is connected to the voltage dividing point of the first voltage dividing circuit 101, that is, the reference voltage end of the voltage reference source is connected between the resistor R1 and the resistor R2, and the ground end of the voltage reference source is grounded.

[0078] The first end of the second voltage divider circuit 102 is used to connect to the power supply, and the second end of the second voltage divider circuit 102 is connected to the start end of the voltage reference source (such as Figure 2 2 pins as shown) and the voltage dividing point of the first voltage dividing circuit 101, the second voltage dividing circuit 102 includes Figure 2 The resistor R3 and the resistor R4 shown, the first end of the resistor R3 is used to connect to the power supply, the second end of the resistor R3 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the start end of the voltage reference source, and the second end of the resistor R4 is also connected between the resistor R1 and the resistor R2.

[0079] The third transistor (such as Figure 2 The base B of the transistor D1) is connected to the voltage dividing point of the second voltage dividing circuit 102, and the emitter E of the third transistor is used to connect to the power supply. Optionally, the hysteresis circuit further includes a current limiting resistor (such as Figure 2As shown in FIG5 , the first end of the current limiting resistor is connected to the voltage dividing point of the second voltage dividing circuit, that is, the first end of the resistor R5 can be connected between the resistor R3 and the resistor R4, and the second end of the current limiting resistor is connected to the base of the third transistor, that is, the second end of the resistor R5 is connected to the base B of the third transistor.

[0080] The first parallel resistor (such as Figure 2 The first end of R6 shown in FIG. 1 is connected to the second end of the second voltage divider circuit 102, and the second parallel resistor (such as Figure 2 The first end of R7 shown is grounded, and the collector C of the third transistor, the second end of the first parallel resistor and the second end of the second parallel resistor are all connected to the output end of the hysteresis circuit.

[0081] Alternatively, as Figure 2 As shown, the hysteresis circuit 100 may further include a filter capacitor C1 and an energy storage capacitor C2. The filter capacitor C1 is connected in parallel across the resistor R2, and the energy storage capacitor C2 is connected in parallel across the resistor R7.

[0082] The hysteresis circuit 100 can change the parallel equivalent resistance of R1 and R2 by turning transistor D1 on and off, thereby setting the power-up voltage threshold and power-down voltage threshold. When transistor D1 is turned on, the output terminal VDD_5V_EN of the hysteresis circuit 100 is energized and can be used to control the subsequent circuit.

[0083] The following, combined Figure 2 , the circuit principle of the hysteresis circuit 100 is introduced as an example.

[0084] It can be understood that if the transistor D1 is turned on, that is, the base B and emitter E of the transistor D1 are turned on, if the power supply voltage (VDD_5V1), BE, R5, R4, and U1 can form a loop, then the collector C and emitter E of the transistor D1 are equivalent to a wire. At this time, it is equivalent to the power supply being connected to one end of R6, one end of R1 being connected to the power supply, and R1 and R6 being connected together at pin 1 of U1. Therefore, when the transistor D1 is turned on, R1 and R6 are connected in parallel.

[0085] If transistor D1 is disconnected, that is, the base B and emitter E of transistor D1 are disconnected, if the power supply voltage (VDD_5V1), BE, R5, R4, and U1 cannot form a loop, then CE cannot be equivalent to a wire. At this time, R6 and R7 are connected, one end of R2 is connected to pin 1 of U1 and one end of R6, and the other end of R2 is connected to R7. In this way, it is equivalent to connecting R6 and R7 in series and then in parallel with R2.

[0086] In this way, since the transistor D1 has the two states of on and off, by switching between the two states, the parallel equivalent resistance of R1 and R2 can be changed respectively, thereby setting the power-on voltage threshold and the power-off voltage threshold.

[0087] Next, the circuit principle of the hysteresis circuit 100 is introduced by taking the power-on process and the power-off process as examples.

[0088] During the power-on process, as the power supply voltage VDD_5V1 gradually increases from 0, if the voltage divided by pin 1 of U1 does not reach the reference voltage Uref, U1 will not be turned on. At this time, as mentioned above, the power supply voltage (VDD_5V1), BE, R5, R4, and U1 cannot form a loop. Then, at this time, it is equivalent to R6 and R7 being connected in series and then in parallel with R2 as the parallel equivalent resistance at both ends of R2.

[0089] In this case, the calculation formula of the power-on voltage threshold Uon that can turn on U1 is as follows:

[0090]

[0091] After the power supply voltage VDD_5V1 reaches the power-on voltage threshold, U1 is turned on, and the power supply voltage (VDD_5V1), BE, R5, R4, and U1 form a loop. R1 and R6 are connected in parallel. During the power-off process, the power supply voltage drops to the power-on voltage threshold and U1 cannot be turned off. The calculation formula for the power-off voltage threshold Uoff is as follows:

[0092]

[0093] In this way, after the power supply voltage VDD_5V1 drops to the power-down voltage threshold, U1 is turned off, the transistor D1 is turned off, and the output terminal VDD_5V_EN of the hysteresis circuit 100 is turned off.

[0094] In actual implementation, the resistance values ​​of the various resistors in the hysteresis circuit 100 can be flexibly set according to the desired power-on voltage threshold and power-off voltage threshold, thereby flexibly setting the power-on voltage threshold and power-off voltage threshold as needed. In the embodiment of the present application, the power-on voltage threshold is greater than the power-off voltage threshold, which can reduce the impact of power supply voltage fluctuations on subsequent circuits.

[0095] Therefore, during the power-on process, the hysteresis circuit 100 is used to switch to the on state when the power voltage of the power supply reaches the power-on voltage threshold, and the power monitoring module 200 is used to output a first level signal when the voltage input to the hysteresis circuit 100 reaches the monitoring voltage threshold.

[0096] In an embodiment of the present application, the first input end of the switch control circuit 300 is used to connect to the power supply, the second input end of the switch control circuit 300 is connected to the output end of the power supply monitoring module 200, and the output end of the switch control circuit 300 is used to connect to the load. The switch control circuit 300 is used to switch to the on state when a first level signal is detected, so that the power supply path of the load can be turned on. The load can be, for example, a PMIC and an SOC.

[0097] During the power-off process, the hysteresis circuit 100 is used to switch to an open circuit state when the power supply voltage drops to a power-off voltage threshold, the power supply monitoring module 200 is used to output a second level signal when the voltage input to the hysteresis circuit 100 drops to a monitoring voltage threshold, and the switch control circuit 300 is used to switch to an off state when the second level signal is detected, thereby disconnecting the power supply path of the load.

[0098] In the above embodiment, the power supply voltage is compared with the power-on voltage threshold and the power-off voltage threshold via the hysteresis circuit 100. When the power supply voltage fluctuates widely, in the embodiment of the present application, the hysteresis circuit 100 is turned on only when the power supply voltage reaches the power-on voltage threshold. The subsequent-stage circuit is turned on only when the voltage input to the subsequent stage of the hysteresis circuit 100 reaches the monitoring voltage threshold. During power-off, the hysteresis circuit 100 is turned off only when the power supply voltage drops to the power-off voltage threshold. The power supply monitoring module 200 and the switch control circuit 300 are powered off only when the power supply voltage drops to the monitoring voltage threshold. In this way, when the switching circuit provided in the embodiment of the present application is used in an HMI product, it is possible to avoid the problem of repeated powering on and off of the subsequent-stage circuit in a short period of time due to power supply voltage fluctuations, which could cause abnormal power-on and power-off of the HMI product and damage to the software and hardware. The embodiment of the present application can achieve safe power-on and power-off of the HMI product.

[0099] In one embodiment, based on the above Figure 1 or Figure 2 In the embodiment shown, the circuit structure and circuit principle of the switch control circuit 300 are exemplarily introduced below.

[0100] See also Figure 3 The switch control circuit 300 may include a first control circuit 301 , a second control circuit 302 , a third control circuit 303 and a switch module 304 .

[0101] Among them, the first control circuit 301 is connected to the output end of the power supply monitoring module 200; the second control circuit 302 is connected to the power supply, and the second control circuit 302 is connected to the first control circuit 301; the third control circuit 303 is connected to the power supply, and the third control circuit 303 is connected to the second control circuit 302; the switch module 304 is connected to the third control circuit 303, the switch module 304 is also connected to the power supply, and the switch module 304 is used to connect to the load.

[0102] In the following, the first control circuit 301 , the second control circuit 302 , the third control circuit 303 and the switch module 304 are respectively introduced with reference to the drawings.

[0103] See also Figure 4 , the first control circuit 301 includes a first voltage dividing resistor (such as Figure 4 R12 shown), the second voltage divider resistor (such as Figure 4 R13 shown) and the first transistor (as Figure 4 D2 shown).

[0104] Among them, the first end of the first voltage-dividing resistor R12 is connected to the output end of the power supply monitoring module 200, the first end of the second voltage-dividing resistor R13 is connected to the second end of the first voltage-dividing resistor R12, the second end of the second voltage-dividing resistor R13 is grounded, the base B of the first transistor D2 is connected between the first voltage-dividing resistor R12 and the second voltage-dividing resistor R13, the collector C of the first transistor D2 is connected to the second control circuit 302, and the emitter E of the first transistor D2 is grounded.

[0105] The connection between the collector C of the first transistor D2 and the second control circuit 302 and the circuit principle of the first control circuit 301 will be described in the following embodiments.

[0106] Optionally, the first control circuit 301 further includes a first filter capacitor (such as Figure 4 As shown in FIG. 4 , the first filter capacitor C6 is connected in parallel with the second voltage-dividing resistor R13 . The first filter capacitor C6 can prevent the first transistor D2 from being mis-conducted.

[0107] Please continue to see Figure 4 , the second control circuit 302 includes a third voltage dividing resistor (such as Figure 4 R14 shown), the fourth voltage divider resistor (such as Figure 4 R15 shown) and the second transistor (as Figure 4 D3 shown).

[0108] Among them, the first end of the third voltage-dividing resistor R14 is used to connect to the power supply, the second end of the third voltage-dividing resistor R14 is connected to the collector C of the first transistor D2, the first end of the fourth voltage-dividing resistor R15 is connected to the second end of the third voltage-dividing resistor R14, the second end of the fourth voltage-dividing resistor R15 is grounded, the base B of the second transistor D3 is connected between the third voltage-dividing resistor R14 and the fourth voltage-dividing resistor R15, the collector C of the second transistor D3 is connected to the third control circuit 303, and the emitter E of the second transistor D3 is grounded.

[0109] The connection between the collector C of the second transistor D3 and the third control circuit 303 and the circuit principle of the second control circuit 302 will be described in the following embodiments.

[0110] Optionally, the second control circuit 302 further includes a second filter capacitor (such as Figure 4 As shown in FIG. 4 , the second filter capacitor C7 is connected in parallel with the fourth voltage-dividing resistor R15 . The second filter capacitor C7 can prevent the second transistor D3 from being mis-conducted.

[0111] Please continue to see Figure 4 , the third control circuit 303 includes a fifth voltage dividing resistor (such as Figure 4 R17 shown), the sixth voltage divider resistor (such as Figure 4 R18 shown), pull-down resistor (such as Figure 4 R16 shown) and the first energy storage capacitor (such as Figure 4 C8 shown).

[0112] Among them, the first end of the fifth voltage-dividing resistor R17 is used to connect to the power supply, the second end of the fifth voltage-dividing resistor R17 is connected to the collector C of the second transistor D3, the first end of the sixth voltage-dividing resistor R18 is connected to the second end of the fifth voltage-dividing resistor R17, the first end of the pull-down resistor R16 is connected to the second end of the sixth voltage-dividing resistor R18, the second end of the pull-down resistor R16 is grounded, the switch module 304 is connected between the sixth voltage-dividing resistor R18 and the pull-down resistor R16, and the first energy storage capacitor C8 is connected in parallel with the pull-down resistor R16.

[0113] The connection between the switch module 304 and the sixth voltage-dividing resistor R18 and the pull-down resistor R16 , and the circuit principle of the third control circuit 303 will be described in the following embodiments.

[0114] Please continue to see Figure 4 , the switch module 304 includes:

[0115] The seventh voltage divider resistor (such as Figure 4 R20 shown in the figure), the eighth voltage divider resistor (R19 shown in the figure), the first MOS switch tube (as shown in the figure Figure 4D4 shown) and the second MOS switch tube (such as Figure 4 D5 shown).

[0116] Among them, the first end of the seventh voltage-dividing resistor R20 is used to be connected to the power supply, the first end of the eighth voltage-dividing resistor R19 is connected to the second end of the seventh voltage-dividing resistor R20, the control electrode of the first MOS switch tube D4 is connected between the sixth voltage-dividing resistor R18 and the pull-down resistor R16, the first electrode of the first MOS switch tube D4 is connected to the second end of the eighth voltage-dividing resistor R19, the second electrode of the first MOS switch tube D4 is grounded, the control electrode of the second MOS switch tube D5 is connected between the seventh voltage-dividing resistor R20 and the eighth voltage-dividing resistor R19, the first electrode of the second MOS switch tube D5 is connected to the power supply, and the second electrode of the second MOS switch tube D5 is used to be connected to the load.

[0117] Optionally, the switch module 304 further includes a third filter capacitor (eg Figure 4 As shown in FIG9 , the third filter capacitor C9 is connected in parallel with the seventh voltage-dividing resistor R20.

[0118] The following, combined Figure 4 , the circuit principle of the switch control circuit 300 in the embodiment of the present application is introduced.

[0119] During the power-up process, when the power supply voltage VDD_5V1 gradually increases from 0 (from 0 to 5V), before the power supply voltage reaches the power-up voltage threshold (assuming the power-up voltage threshold is 4.8V and the power-down voltage threshold is 3.8V), the hysteresis circuit 100 is not turned on. Therefore, the voltage input to the power monitoring module 200 by the hysteresis circuit 100 is 0 (lower than the monitoring voltage threshold), and the power monitoring module 200 does not operate.

[0120] At this time, one end of the first voltage-dividing resistor R12, which is closest to the power monitoring module 200, is left floating, while the other end of the first voltage-dividing resistor R12 is grounded via the second voltage-dividing resistor R13. Since the second voltage-dividing resistor R13 is grounded, the voltage across BE of the first transistor D2 is zero, and the first transistor D2 is disconnected. The third voltage-dividing resistor R14 and the fourth voltage-dividing resistor form a voltage-dividing circuit to divide the power supply voltage VDD_5V1. As the power supply voltage VDD_5V1 increases, the voltage across BE of the second transistor D3 exceeds the BE conduction threshold of the second transistor D3 (e.g., 0.7V), causing the second transistor D3 to conduct. After the second transistor D3 is turned on, the CE terminal of the second transistor D3 is equivalent to a wire. At this time, the sixth voltage-dividing resistor R18 and the pull-down resistor R16 are short-circuited by the second transistor D3, and the voltage across the sixth voltage-dividing resistor R18 is zero. Since the sixth voltage-dividing resistor R18 is connected to the control electrode of the first MOS switch D4, the first MOS switch D4 is in the off state. When the first MOS switch D4 is in the off state, it is equivalent to the eighth voltage-dividing resistor R19 and the seventh voltage-dividing resistor R20 not being grounded, and therefore the two cannot form a voltage-dividing circuit. Therefore, the seventh voltage-dividing resistor R20 is connected in parallel across the GS terminal of the second MOS switch D5. Since there is no voltage difference across the GS terminal, the second MOS switch D5 is also in the off state.

[0121] Therefore, the input voltage VDD_5V_EN of the hysteresis circuit 100 serves as the voltage monitoring point of the power monitoring module 200. When the input voltage of the hysteresis circuit 100 does not reach the monitoring voltage threshold, even if the power supply voltage VDD_5V1 is present, the switch control circuit 300 will not be turned on. Therefore, the load will not be powered by VDD_5V_CORE.

[0122] Thus, when the power supply voltage does not reach the power-on voltage threshold and the input voltage of the hysteresis circuit 100 does not reach the monitoring voltage threshold, the power monitoring module 200 does not work, the second MOS switch D5 is in the off state, and the power supply circuit of the load is disconnected.

[0123] After the power supply voltage VDD_5V1 increases to the power-on voltage threshold, the hysteresis circuit 100 inputs a voltage signal to the power monitoring module 200. When the input voltage is greater than the monitoring voltage threshold, the power monitoring module 200 outputs a first-level signal (e.g., a high-level signal). In this way, the first voltage-dividing resistor R12 and the second voltage-dividing resistor R13 form a voltage-dividing circuit. As long as the voltage across the second voltage-dividing resistor R13 is greater than the BE conduction threshold of the first transistor D2 (e.g., 0.7V), the BE terminal of the first transistor D2 is turned on, and the CE terminal of the first transistor D2 is equivalent to a wire. In this way, the B terminal (base) voltage of the second transistor D3 can be pulled to 0, and the second transistor D3 is turned off.

[0124] In this way, since the left side of the sixth voltage-dividing resistor R18 is not grounded, the power supply voltage can charge the first energy storage capacitor C8 through the fifth voltage-dividing resistor R17 and the sixth voltage-dividing resistor R18. When the voltage across the first energy storage capacitor C8 reaches the conduction threshold of the first MOS switch tube D4, the first MOS switch tube D4 is turned on, so that the eighth voltage-dividing resistor R19 and the seventh voltage-dividing resistor R20 form a voltage-dividing circuit and start voltage division, thereby controlling the second MOS switch tube D5 to be turned on, so that the load can be powered.

[0125] The calculation formula for the charging time T1 of the first energy storage capacitor C8 is as follows:

[0126]

[0127]

[0128]

[0129] Wherein, R is the resistance of the fifth voltage divider resistor R17, C is the capacitance of the first energy storage capacitor C8, VGSth is the conduction threshold of the first MOS switch D4, VDD 5V1 is the power supply voltage, V0 is 0V. In actual implementation, the specifications of the resistor and capacitor can be selected according to the required charging time T1.

[0130] During the power-off process, the power supply voltage, the input voltage of the power monitoring module 200, and the output voltage (VDD_5V_CORE) of the switch control circuit 300 are simultaneously powered down. When the power supply voltage drops below the power-off voltage threshold, the power monitoring module 200 outputs a second-level signal (a low-level signal), turning off the first transistor D2. At this point, the third and fourth voltage-dividing resistors R14 and R15 act as a voltage divider, allowing the second transistor D3 to remain on. The first energy storage capacitor C8 discharges through the sixth voltage-dividing resistor R18 and the second transistor D3. The first energy storage capacitor C8 can be a uF capacitor. Although the power supply voltage is still charged, the first energy storage capacitor C8 quickly discharges, turning off the first MOS switch D4 and the second MOS switch D5. VDD_5V_CORE is disconnected from the preceding stage's VDD_5V1, and the VDD_5V_CORE power-off monotonicity remains unchanged, ensuring that downstream loads experience no abnormalities during power-off.

[0131] The discharge time T2 is calculated as follows:

[0132]

[0133]

[0134] Wherein, R is the resistance of the sixth voltage-dividing resistor R18, C is the capacitance of the first energy storage capacitor C8, and the meanings of other parameters can refer to the relevant description of the above embodiment.

[0135] In the embodiment of the present application, the sixth voltage-dividing resistor R18 can be 100Ω, and the fifth voltage-dividing resistor R17 and the pull-down resistor R16 can be in the hundreds of kΩ level, thereby achieving the functions of delayed opening on power-up and fast closing on power-down.

[0136] Alternatively, see Figure 4 , the switch circuit of the embodiment of the present application further includes a second energy storage capacitor (such as Figure 4 As shown in C10, the first electrode of the second energy storage capacitor is connected to the second electrode of the second MOS switch tube, the first electrode of the second energy storage capacitor is connected to the second electrode of the first MOS switch tube, and the second energy storage capacitor is used to store energy and supply power to the subsequent load.

[0137] In an embodiment of the present application, the power monitoring module 200 (or referred to as the power monitor) and the switch control circuit 300 form a slow-start and fast-stop circuit. The switch control circuit 300 is mainly constructed by transistors, MOS tubes, capacitors and resistors, which is conducive to cost control.

[0138] During the power-on process, the slow-on, fast-off circuit controls the MOS tubes (the first MOS switch tube and the second MOS switch tube) to delay opening. During the power-off process, the MOS tubes are quickly turned off through the discharge of the capacitor (the first energy storage capacitor), thereby realizing the slow-on, fast-off function for the load power supply circuit. This provides sufficient time interval between the two power-on times of subsequent loads (such as PMIC and SOC) for completely shutting down the subsequent loads.

[0139] This ensures safe power on and off of loads such as the CPU and PMIC during repeated power cycles, and prevents input voltage oscillation from affecting subsequent circuits during power-off.

[0140] In one embodiment, based on any of the above embodiments, in an embodiment of the present application, the switch circuit further includes a tank circuit, the input end of the tank circuit is used to be connected to a power supply, and the output end of the tank circuit is grounded.

[0141] For example, see Figure 5 , Figure 5 is a schematic diagram of an exemplary energy storage circuit 400. The energy storage circuit 400 includes capacitors C3, C4, and C5, resistors R8-R11, and a diode D6. The charging time T3 of the energy storage circuit 400 during power-on and the discharging time T4 during power-off are calculated by the following formula:

[0142] The energy storage circuit 400 acts as a supercapacitor, and its total capacity C is:

[0143]

[0144] Time constant

[0145] Charging time

[0146] During the power-off process, the discharge time T4 can be estimated based on the maximum current I required by the subsequent circuit:

[0147]

[0148]

[0149] In the embodiment of the present application, the energy storage circuit 400 can mitigate the impact of the inrush current when the circuit is powered on, protecting the subsequent circuit from damage by the inrush current; when the circuit is powered off, it can provide reserve power to meet the system power-off preservation requirements and protect the file system from damage.

[0150] Currently, HMI products require power reserves to meet the system's file storage needs when the entire device loses power, and the software processing mechanism is highly dependent on power-off storage capabilities. In this embodiment of the application, by providing an energy storage circuit 400, the power-off protection requirements of the HMI product can be met when the power is off.

[0151] In addition, HMI products are generally divided into display, touch and baseboard control in the overall structure. The screen signal timing when the HMI product is turned on and off greatly affects the display effect of the display screen. The embodiment of the present application can solve the display screen timing requirements when powering on, off and off through safe power on and off.

[0152] The embodiment of the present application proposes a solution of using a supercapacitor + hysteresis circuit 100 + slow opening and fast closing, which is constructed as a whole using separate components. It can not only meet the safety power on and off requirements of current HMI products, but also has great advantages in cost and procurement.

[0153] In one embodiment, a power supply circuit is further provided, comprising a power supply and a switching circuit as described in any one of the above embodiments, wherein the power supply is connected to the switching circuit.

[0154] The relevant implementation methods and beneficial effects of the power supply circuit in the embodiment of the present application and the relevant implementation methods and beneficial effects of the switching circuit above can be found in the relevant description above and will not be repeated here.

[0155] In the description of this specification, reference to the terms "some embodiments" or "other embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0156] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0157] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A switching circuit, characterized in that: include: a hysteresis circuit, wherein an input end of the hysteresis circuit is connected to a power supply; a power monitoring module, wherein an input end of the power monitoring module is connected to an output end of the hysteresis circuit; a switch control circuit, wherein a first input terminal of the switch control circuit is connected to the power supply, a second input terminal of the switch control circuit is connected to the output terminal of the power monitoring module, and an output terminal of the switch control circuit is connected to a load; During the power-on process, the hysteresis circuit is configured to switch to a conductive state when the power supply voltage of the power supply reaches a power-on voltage threshold, the power monitoring module is configured to output a first level signal when the voltage input to the hysteresis circuit reaches a monitoring voltage threshold, and the switch control circuit is configured to switch to a conductive state when the first level signal is detected; During the power-off process, the hysteresis circuit is used to switch to an open circuit state when the power supply voltage drops to a power-off voltage threshold, the power supply monitoring module is used to output a second level signal when the voltage input to the hysteresis circuit drops to the monitoring voltage threshold, and the switch control circuit is used to switch to an off state when the second level signal is detected.

2. The switching circuit according to claim 1, wherein: The switch control circuit includes: a first control circuit connected to an output terminal of the power monitoring module; a second control circuit, the second control circuit being connected to the power supply and the second control circuit being connected to the first control circuit; a third control circuit, the third control circuit being connected to the power supply and the third control circuit being connected to the second control circuit; A switch module is connected to the third control circuit, is further connected to the power supply, and is used to connect to the load.

3. The switching circuit according to claim 2, wherein: The first control circuit includes: a first voltage-dividing resistor, wherein a first end of the first voltage-dividing resistor is connected to an output end of the power monitoring module; a second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor is connected to a second end of the first voltage-dividing resistor, and a second end of the second voltage-dividing resistor is grounded; A first transistor, wherein the base of the first transistor is connected between the first voltage-dividing resistor and the second voltage-dividing resistor, the collector of the first transistor is connected to the second control circuit, and the emitter of the first transistor is grounded.

4. The switching circuit according to claim 3, wherein: The second control circuit includes: a third voltage-dividing resistor, wherein a first end of the third voltage-dividing resistor is used to be connected to the power supply, and a second end of the third voltage-dividing resistor is connected to the collector of the first transistor; a fourth voltage-dividing resistor, wherein a first end of the fourth voltage-dividing resistor is connected to the second end of the third voltage-dividing resistor, and a second end of the fourth voltage-dividing resistor is grounded; A second triode, wherein the base of the second triode is connected between the third voltage-dividing resistor and the fourth voltage-dividing resistor, the collector of the second triode is connected to the third control circuit, and the emitter of the second triode is grounded.

5. The switching circuit according to claim 4, characterized in that: The third control circuit includes: a fifth voltage-dividing resistor, wherein a first end of the fifth voltage-dividing resistor is used to be connected to the power supply, and a second end of the fifth voltage-dividing resistor is connected to the collector of the second transistor; a sixth voltage-dividing resistor, a first end of the sixth voltage-dividing resistor being connected to the second end of the fifth voltage-dividing resistor; a pull-down resistor, wherein a first end of the pull-down resistor is connected to the second end of the sixth voltage-dividing resistor, a second end of the pull-down resistor is grounded, and the switch module is connected between the sixth voltage-dividing resistor and the pull-down resistor; A first energy storage capacitor is connected in parallel with the pull-down resistor.

6. The switching circuit according to claim 5, characterized in that: The switch module includes: a seventh voltage-dividing resistor, wherein a first end of the seventh voltage-dividing resistor is configured to be connected to the power supply; an eighth voltage-dividing resistor, a first end of the eighth voltage-dividing resistor being connected to the second end of the seventh voltage-dividing resistor; a first MOS switch tube, wherein a control electrode of the first MOS switch tube is connected between the sixth voltage-dividing resistor and the pull-down resistor, a first electrode of the first MOS switch tube is connected to the second end of the eighth voltage-dividing resistor, and a second electrode of the first MOS switch tube is grounded; a second MOS switch tube, wherein the control electrode of the second MOS switch tube is connected between the seventh voltage-dividing resistor and the eighth voltage-dividing resistor, the first electrode of the second MOS switch tube is connected to the power supply, and the second electrode of the second MOS switch tube is used to be connected to the load.

7. The switching circuit according to claim 1, wherein: The hysteresis circuit comprises: a first voltage divider circuit, wherein a first end of the first voltage divider circuit is used to be connected to the power supply, and a second end of the first voltage divider circuit is grounded; a voltage reference source, wherein a reference voltage terminal of the voltage reference source is connected to a voltage dividing point of the first voltage dividing circuit, and a ground terminal of the voltage reference source is grounded; a second voltage divider circuit, wherein a first end of the second voltage divider circuit is used to be connected to the power supply, and a second end of the second voltage divider circuit is connected to an enable end of the voltage reference source and a voltage dividing point of the first voltage divider circuit; a third triode, wherein the base of the third triode is connected to the voltage dividing point of the second voltage dividing circuit, and the emitter of the third triode is used to be connected to the power supply; A first parallel resistor and a second parallel resistor, wherein the first end of the first parallel resistor is connected to the second end of the second voltage divider circuit, the first end of the second parallel resistor is grounded, and the collector of the third transistor, the second end of the first parallel resistor and the second end of the second parallel resistor are all connected to the output end of the hysteresis circuit.

8. The switching circuit according to claim 7, wherein: The hysteresis circuit further includes: a current-limiting resistor, wherein a first end of the current-limiting resistor is connected to a voltage dividing point of the second voltage-dividing circuit, and a second end of the current-limiting resistor is connected to a base of the third transistor.

9. The switching circuit according to any one of claims 1 to 8, characterized in that: The switching circuit further includes: An energy storage circuit, wherein the input end of the energy storage circuit is used to be connected to the power supply, and the output end of the energy storage circuit is grounded.

10. A power supply circuit, characterized in that: The device comprises a power supply and a switching circuit according to any one of claims 1 to 9, wherein the power supply is connected to the switching circuit.

Images