Low-power bistable self-locking button circuit and wireless charging system

Abstract

The present application provides a low-power bistable self-locking key circuit and a wireless charging system, wherein the key circuit includes a key, a switch module, a driving capacitor, a voltage-dividing resistor, and two switching modules; when the key is pressed, two separate contacts are connected; the first end of each switching module is connected to the power supply end through a pull-up resistor, and the second end of each switching module is connected to the ground end; the first end of each switching module is also connected to the enable end and a contact of another switching module; the voltage-dividing resistor is connected in series between the first end of one of the switching modules and the contact connected thereto, and the driving capacitor is connected in series between the contact and the ground end; the switch module is connected in series between the power supply path between the power supply end and the output end, and its enable end is connected to the first end of one of the switching modules. The key circuit provided by the present application has low power consumption, is sensitive to response, and does not require a separate power supply.

Description

Technical Field

[0001] The present application belongs to the field of electrical engineering and further relates to an electronic circuit based on semiconductor devices. Specifically, a low-power bistable self-locking key circuit and a wireless charging system using the key circuit are provided. Background Art

[0002] When controlling various household and industrial appliances, it's often necessary to use buttons to switch the circuit on or off. A common switching method is to toggle the circuit on or off each time the button is pressed, and maintain the on / off state after the button is released until it is pressed again. This type of button is also called a self-locking button. Self-locking buttons can take various forms, including mechanical self-locking buttons and circuit-controlled self-locking button circuits.

[0003] Currently, common self-locking key circuits are mainly implemented through programmable chips such as MCUs. The pins connected to the key contacts and other positions obtain the electrical signals corresponding to the key actions, and the program pre-burned in the chip is used to perform logical judgment of the key actions to realize the function of the self-locking key.

[0004] However, the above-mentioned existing self-locking button circuit is relatively expensive, and the chip itself requires a power supply to maintain its normal operation. In particular, when the above-mentioned self-locking button circuit is applied to the circuit control of a wireless charging system, since the charging receiving end cannot power the chip when the transmitting end is not working, it is necessary to equip the chip with an additional auxiliary power supply such as a battery, which further increases the cost and power consumption. Summary of the Invention

[0005] To address the problems in the prior art, the present application aims to provide a novel bistable self-locking key circuit and a wireless charging system incorporating the same. The key circuit utilizes discrete components, resulting in high response accuracy and sensitivity, low component cost, and no need for a separate power supply, resulting in no additional power consumption.

[0006] A first aspect of the present application provides a low-power bistable self-locking key circuit, comprising a key, a switch module, a drive capacitor, and two switching modules. The key connects two separate contacts when pressed, and the switch module is connected in series between the power supply path of the power supply end and the output end.

[0007] Specifically, the first end of each switching module is connected to the enable end of another switching module, and is connected to the power supply end through a pull-up resistor, and the second end of each switching module is connected to the ground end, and the enable end is used to control the on-off state of the switching module; the first end of each switching module is respectively connected to a contact, a voltage divider resistor is connected in series between the first end of one switching module and the corresponding contact, and the driving capacitor is connected in series between the contact and the ground end; the enable end of the switch module is connected to the first end of one of the switching modules for controlling the on-off state of the power supply path.

[0008] Preferably, the resistance of the voltage-dividing resistor is much greater than the resistance of the pull-up resistor.

[0009] Preferably, the low-power bistable self-locking key circuit further includes a current-limiting resistor, which is connected in series between a contact not connected to the driving capacitor and a first end of the switching module connected to the contact.

[0010] Preferably, the resistance of the pull-up resistor is much greater than the resistance of the current-limiting resistor.

[0011] Preferably, the capacitance range of the driving capacitor is [4.7nF, 27nF].

[0012] Preferably, the switching module is an NMOS tube, whose G pole is the enable terminal, D pole is the first terminal, and S pole is the second terminal; and the switch module is a PMOS tube, whose G pole is the enable terminal, D pole is the first terminal, and S pole is the second terminal.

[0013] A second aspect of the present application provides a wireless charging system, including a wireless charging transmitting circuit, a wireless charging receiving circuit, and a key self-locking circuit;

[0014] The wireless charging receiving circuit converts the electromagnetic waves emitted by the wireless charging transmitting circuit into electrical signals at the power supply end through energy coupling, and charges the load through the output end; the key self-locking circuit is the above-mentioned low-power bistable self-locking key circuit, which is connected to the wireless charging receiving circuit or the wireless charging transmitting circuit.

[0015] Preferably, an LED light is connected in series between the power supply terminal and the ground terminal of the wireless charging receiving circuit to display the charging status of the wireless charging receiving circuit.

[0016] Compared with various existing key circuits, the technical solution of this application has at least the following beneficial effects:

[0017] The low-power bistable self-locking key circuit provided by the present application cyclically connects the enable terminals and first terminals of two high-level conducting switching modules to each other, so that their on and off states are always in opposite phases. A driving capacitor then provides a state switching "drive signal" to one of the switching modules each time a key is pressed. A voltage divider resistor is used to isolate the potential across the driving capacitor, so that the key circuit can be locked in a stable state after each state switch.

[0018] At the same time, a low-level conduction switch module is used to control the on-off state of the power circuit, so that when the power supply end is powered on again, the key circuit remains in a stable off-circuit state, avoiding the problem of the power circuit being accidentally connected during the power-on process;

[0019] In addition, the button circuit can share power with the power supply end, and can still ensure normal operation even if the power supply end is powered on again after power failure. Therefore, no additional power supply is required, which further reduces power consumption and greatly expands the application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of an application scenario of a low-power bistable self-locking key circuit provided according to an embodiment of the present application;

[0021] Figure 2 A circuit schematic diagram of a low-power bistable self-locking key circuit provided according to some embodiments of the present application;

[0022] Figure 3 A circuit schematic diagram of a low-power bistable self-locking key circuit provided according to some other embodiments of the present application;

[0023] Figure 4 A specific circuit diagram of a low-power bistable self-locking key circuit provided according to an embodiment of the present application;

[0024] Figure 5 4 is a circuit diagram of a wireless charging system provided according to an embodiment of the present application.

[0025] Numbers in the figure

[0026] 10: button, 11: first switching module, 111: first pull-up resistor, 12: second switching module, 121: second pull-up resistor, 13: switch module, 21: driving capacitor, 22: voltage divider resistor, 23: current limiting resistor. DETAILED DESCRIPTION

[0027] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0028] In addition, various components in the drawings are enlarged or reduced in size for ease of understanding, but this is not intended to limit the scope of protection of this application.

[0029] Words importing the singular include the plural and vice versa.

[0030] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or are the orientation or positional relationship in which the products of the embodiments of the present application are usually placed when in use, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, in the description of the present application, in order to distinguish different units, words such as first and second are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance. Their names may be different in the detailed description and claims of the present application.

[0031] The vocabulary in this specification is used to illustrate the embodiments of the present application, but is not intended to limit the present application. It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a communication between the two components. For those skilled in the art, the specific meanings of the above terms in this application can be specifically understood.

[0032] A first aspect of the embodiments of the present application provides a low-power bistable self-locking key circuit, Figure 1 A schematic diagram of a practical application scenario of the key circuit is shown in FIG. Figure 1 As shown, the low-power bistable self-locking key circuit provided in the embodiment of the present application can be used to control the on / off state of a circuit between a power supply terminal VDD and an output terminal OUTPUT, wherein the output terminal OUTPUT is used to power a connected load. In addition, those skilled in the art can also apply the circuit to control the on / off state of other types of circuits as needed.

[0033] Figure 2 FIG. 4 shows a circuit schematic diagram of a low-power bistable self-locking key circuit according to some preferred embodiments of the present application, as shown in FIG. Figure 2 As shown, the key circuit includes a key 10 , a first switching module 11 , a second switching module 12 , a switch module 13 , a driving capacitor 21 and a voltage dividing resistor 22 .

[0034] Specifically, if Figure 2As shown, the key 10 connects two separate contacts a1 and a2 when pressed. For the key circuit provided in this application, those skilled in the art should know that the connections mentioned here and below are all electrical connections.

[0035] In the actual process of selecting circuit components, those skilled in the art can select a suitable type of key 10 according to specific design requirements, such as a micro-touch key, a mechanical key, a touch key, etc.

[0036] Specifically, if Figure 2 As shown, the first end b1 of the first switching module 11 is connected to the power supply end VDD through the first pull-up resistor 111, and the second end b2 is connected to the ground end GND; at the same time, the first end c1 of the second switching module 12 is connected to the power supply end VDD through the second pull-up resistor 121, and the second end c2 is connected to the ground end.

[0037] Specifically, if Figure 2 As shown, the first end b1 of the first switching module 11 is also connected to the enable end c3 of the second switching module 12, and the enable end c3 is used to control the on / off state of the second switching module 12. At the same time, the first end c1 of the second switching module 12 is also connected to the enable end b3 of the first switching module 11, and the enable end b3 is used to control the on / off state of the first switching module 11. In the embodiment of the present application, when the enable end b3 of the first switching module 11 is at a high level, the first end b1 and the second end b2 are connected, otherwise, the first end b1 and the second end b2 are disconnected; when the enable end c3 of the second switching module 12 is at a high level, the first end c1 and the second end c2 are connected, otherwise, the first end c1 and the second end c2 are disconnected.

[0038] Specifically, if Figure 2 As shown, the first end b1 of the first switching module 11 is also connected to the contact a1, and the first end c1 of the second switching module 12 is also connected to the contact a2; at the same time, the voltage divider resistor 22 is connected in series between the first end b1 of the first switching module 11 and the contact a1 connected thereto, and the driving capacitor 21 is connected in series between the contact a1 and the ground terminal GND.

[0039] In some preferred embodiments, the first switching module 11 may use an NMOS transistor, whose G pole, D pole and S pole correspond to the enable terminal b3, the first terminal b1 and the second terminal b2 respectively; in other preferred embodiments, the first switching module 11 may also use an NPN transistor, whose base, collector and emitter correspond to the enable terminal b3, the first terminal b1 and the second terminal b2 respectively; similarly, the second switching module 12 may also use an NMOS transistor or an NPN transistor, and the corresponding relationship between its various terminals is the same as that of the first switching module 11, which will not be repeated here.

[0040] Specifically, if Figure 2 As shown, the switch module 13 is connected in series between the power supply terminal VDD and the power supply path of the output terminal OUTPUT. Its enable terminal d3 is connected to the first terminal c1 of the second switching module 12, and is used to control the on / off state of the power supply path between the power supply terminal VDD and the output terminal OUTPUT. In the embodiment of the present application, the first terminal d1 of the switch module 13 is connected to the power supply terminal VDD, and the second terminal d2 is connected to the output terminal. When the enable terminal d3 of the switch module 13 is at a low level, the first terminal d1 and the second terminal d2 are connected. Otherwise, the first terminal d1 and the second terminal d2 are disconnected.

[0041] In some preferred embodiments, the switch module 13 may be a PMOS transistor, whose G pole, S pole and D pole correspond to the enable end d3, the first end d1 and the second end d2 respectively; in other preferred embodiments, the switch module 13 may also be a PNP transistor, whose base, emitter and collector correspond to the enable end d3, the first end d1 and the second end d2 respectively.

[0042] The following combination Figure 2 The circuit diagram shown in the figure explains the working principle of the low power bistable self-locking key circuit. Figure 2 As shown, the low-power bistable self-locking key circuit provided by the present application is used for various types of electrical circuits (i.e. Figure 2 The circuit between the power supply terminal VDD and the output terminal OUTPUT) is switched on and off. Each time the button 10 is pressed, the on and off state of the power circuit is switched. After the button 10 is released, the switched on and off state is maintained until the button 10 is pressed again. Figure 2 As shown, in actual use, the power supply for each module in the key circuit shares a common power source with the power supply for the power-consuming circuits. This common power source may be shut down, lose power, and then restarted. Therefore, it is necessary to ensure that the key circuit does not accidentally switch the power-consuming circuit on or off in various situations, such as using a shared power source or an independent power source.

[0043] First of all, Figure 2 The working condition of the key circuit is described below when the power supply terminal VDD is in a continuous power supply state:

[0044] 1. Assume that the initial time is T0. At this time, the button 10 remains in the pop-up state. At this time, the first terminal b1 of the first switching module 11 is at a low level. b1 is connected to the enable terminal c3 of the second switching module 12, thereby controlling the second switching module 12 to be turned off, so that its first terminal c1 remains at a high level. Since c1 is connected to the enable terminal d3 of the switch module 13, the switch module 13 remains turned off under the control of the high-level enable terminal d3. At this time, the power circuit is in an open circuit state.

[0045] At the same time, since c1 is also connected to the b3 pole, and a2 is not connected to a1 when the button 10 is in the pop-up state, the first switching module 11 remains turned on under the control of the high level b3, so that b1 always maintains a low level, and since the button 10 is in the pop-up state, the upper end level of the driving capacitor 21 is pulled down by b1. At this time, the entire button circuit is in a steady state with b1 at a low level and c1 at a high level, and the power circuit is kept in an open-circuit steady state.

[0046] 2. Key 10 is pressed at time T1 and released until it springs back up at time T2. During the period between T1 and T2, contacts a1 and a2 are connected. Since both ends of driver capacitor 21 are at a low level, at the instant the key is pressed, its upper end is connected to contact b3. b3 instantly goes low, turning off first switch module 11. b1 switches to a high level, which in turn switches second switch module 12 to conduct via c3. This further switches c1 to a low level, and switches switch module 13 to conduct via d3, thus switching the electrical circuit to a closed state.

[0047] It should be noted that during the period when the button is pressed, since a1 and a2 are connected, the upper end of the driving capacitor 21 is continuously pulled down by c1, but due to the presence of the voltage divider resistor 22, b1 remains at a high level, thereby maintaining b1 at a high level and c1 at a low level in a steady state during the period T1 to T2 when the button is pressed, and maintaining the power circuit in a steady state.

[0048] 3. At time T2, the button 10 is released and then bounces up until it is pressed again at time T3. After the button is bounced up, a1 and a2 are no longer connected, and the power supply terminal VDD charges the upper end of the driving capacitor 21 through the pull-up resistor 111 and the voltage divider resistor 22 until the voltage difference between the two ends of the driving capacitor 21 is R 22 / (R 22 +R 111 ), where R 22 、R 111 are the resistance values ​​of the voltage divider resistor 22 and the pull-up resistor 111, respectively. During this period, b1 is always maintained at a high level and keeps the second switching module 12 turned on, thereby keeping c1 at a low level and keeping the switch module 13 turned on under the control of the low level d1;

[0049] At the same time, since c1 is also connected to b3, and a2 is not connected to a1 when the button 10 is in the pop-up state, the first switching module 11 remains on under the control of b3 at a low level, so that b1 always maintains a high level, and since the button 10 is in the pop-up state, the two ends of the driving capacitor 21 always maintain R 22 / (R 22 +R 111) voltage difference, at this time the entire key circuit is in a steady state with b1 being high and c1 being low, and the power-consuming circuit is kept in a steady state.

[0050] 4. The key is pressed again at time T3 and remains pressed until it is released and bounces up again at time T4. During the period from T3 to T4, the two contacts a1 and a2 are connected. At the moment of connection, the capacitor 21 is driven to pull b3 to a high level, turning on the first switching module 11, switching b1 to a low level, and controlling the second switching module 12 to be turned off through c3, further turning c1 to a high level, and controlling the switch module 13 to be turned off through d3, thus switching the electrical circuit to an open state.

[0051] It should be noted that during the period when the button 10 is pressed, since a1 and a2 are connected, the upper end of the driving capacitor 21 is continuously pulled up by c1, but due to the existence of the voltage divider resistor 22, b1 remains at a low level, thereby maintaining b1 at a low level and c1 at a high level in a steady state during the period T3 to T4 when the button 10 is pressed, and the power circuit is maintained in an open-circuit steady state.

[0052] 5. From the moment T4 onwards, the circuit state is exactly the same as that at the moment T0. Thereafter, each pressing and releasing process of the key 10 is a cycle of T0 to T4, which will not be repeated here.

[0053] Secondly, Figure 2 The operation of the key circuit when the power supply terminal VDD is powered on again after a power outage is described. As described above, the low-power bistable self-locking key circuit provided by this application may be applied to the control of various power-consuming circuits. For example, when the key circuit of this application is used to control the charging receiving circuit of a wireless charging system, the charging transmitting circuit may not be transmitting. At this time, the power supply terminal VDD voltage is 0. The power supply terminal VDD is not powered on again until the charging transmitting circuit works again. In this case, the key circuit needs to ensure that the switch module 13 is locked in the off state during the power-on process, thereby ensuring that the power-consuming circuit remains in the off-circuit steady state.

[0054] like Figure 2 As shown, during the process of powering on the power supply end VDD again, the current passes through the first pull-up resistor 111 and the voltage divider resistor 22 to charge the driving capacitor 21. However, since VDD switches b3 to a high level through the second pull-up resistor 121 at the same time, the first switching module 11 is turned on, causing b1 to switch to a low level, thereby pulling down the voltage at the upper end of the driving capacitor 21 again, and turning off the second switching module 12, further switching c1 to a high level, thereby turning off the switch module 13 through d3, and the circuit enters the same open circuit steady state as at time T0.

[0055] It can be seen that the low-power bistable self-locking key circuit provided by the present application is to cyclically connect the enable end and the first end of the two high-level conductive switching modules to each other so that their on-off states are always reversed; provide a "driving signal" for state switching to one of the switching modules by driving the capacitor 21 each time the key is pressed; isolate the potential at both ends of the driving capacitor by the voltage divider resistor 22, so that the key circuit can be locked in a steady state after each state switch. At the same time, the low-level conductive switch module 13 is used to control the on-off state of the power circuit, so that when the power supply terminal VDD is re-powered, the key circuit remains in a stable off-circuit state, avoiding the problem of the power circuit being accidentally connected during the power-on process.

[0056] In addition, since the button circuit can share the power supply VDD and can still operate normally even if the power supply is powered off and then powered on again, no additional power supply is required, which further reduces power consumption and greatly expands the application field.

[0057] Furthermore, in some preferred embodiments, the resistance of the voltage divider resistor 22 is much greater than the resistance of the first pull-up resistor 111 and the second pull-up resistor 121. For example, in some embodiments, the ratio of the resistance of the voltage divider resistor 22 to the resistance of the first pull-up resistor 111 and the second pull-up resistor 121 is greater than or equal to 10. Setting the resistance of the voltage divider resistor 22 to be much greater than the resistance of the pull-up resistors ensures that the potential of the driving capacitor 21 after charging is close to the potential of the power supply terminal VDD, and maintains the potential difference across the voltage divider resistor 22 when a1 and a2 are connected, thereby effectively ensuring the stability of the key circuit.

[0058] Furthermore, to ensure the stability of the circuit, Figure 2 As shown, the key circuit further includes a current-limiting resistor 23, which is connected in series between the first terminal c1 of the second switching module 12 and the contact a2 connected thereto. In some preferred embodiments, the resistance of the first pull-up resistor 111 and the second pull-up resistor 121 is much greater than the resistance of the current-limiting resistor 23. For example, in some embodiments, the ratio of the resistance of the first pull-up resistor 111 and the second pull-up resistor 121 to the resistance of the current-limiting resistor 23 is greater than or equal to 10.

[0059] Furthermore, the capacitance of the driving capacitor 21 also affects the performance of the key circuit. If the capacitance is too small, the enable terminal of the switching module may not be driven to switch states. If the capacitance is too large, the sensitivity may be reduced, resulting in an inability to quickly respond to key presses. To this end, in some preferred embodiments, the capacitance of the driving capacitor 21 ranges from 4.7nF to 27nF. In some preferred embodiments, the capacitance of the driving capacitor is set to 10nF to ensure an optimal balance between driving capability and switching sensitivity.

[0060] Figure 3 A specific circuit diagram of the low-power bistable self-locking key circuit constructed using discrete components is shown in some embodiments.

[0061] Specifically, if Figure 3 As shown, the button 10 of the self-locking button circuit uses a micro-touch button SW1; the two switching modules 11 and 12 are NMOS tubes Q2 and Q3, respectively, and the selected model is 2N7002; the switch module 13 is a PMOS tube Q1, and the selected model is SI2301; the driving capacitor 21 is C1, and the capacitance is 10nF; the voltage divider resistor 22 is R4, and the resistance is 10MΩ; the two pull-up resistors 111 and 121 are R2 and R3, and the resistance is both 1MΩ; the current limiting resistor 23 is R7, and the resistance is 100KΩ.

[0062] Specifically, if Figure 3 As shown, Q2 and Q3 are connected to the 5V power supply through pull-up resistors R2 and R3 respectively, and the output terminal is VIN. Figure 2 The circuit schematic diagram is described in detail and will not be repeated here. Through actual measurement of the key circuit, its actual working power consumption is 4uA.

[0063] It should be noted that Figure 3 In the embodiment shown, a 5V power supply is used as the power supply for Q2 and Q3 and the power supply end of the output end VIN. In addition, in other embodiments, the power supply ends of Q2 and Q3 may not be connected to the power supply end of VIN, that is, the button circuit and the power circuit it controls are powered by different power supplies.

[0064] It should be noted that Figure 2 、 Figure 3 The circuit schematic diagram and the specific circuit diagram shown are circuit connection methods of various modules and components provided according to a specific embodiment of the present application. However, without departing from the technical concept of the present application, other equivalent circuit connection methods may also be provided. For example, Figure 4 A circuit diagram of a key circuit according to another specific embodiment of the present application is shown. Figure 2The difference between the illustrated embodiment and the illustrated embodiment is that the driving capacitor 21 and the voltage-dividing resistor 22 are connected between the contact a1 and the first terminal c1 of the second switching module, and each time the key 10 is pressed and a1 and a2 are connected, a signal for state switching is provided to the enable terminal c3 of the second switching module 12. Thus, in the key circuit provided by the present application, the portion for driving the circuit state switching, which is composed of the driving capacitor 21 and the voltage-dividing resistor 22, can flexibly select to initially drive the first switching module 11 or the second switching module 12, and then utilize the interconnection between the enable terminals of the two switching modules to complete the switching and locking of the circuit state.

[0065] A second aspect of the embodiments of the present application further provides a wireless charging system, Figure 5 FIG. 4 shows a circuit diagram of a wireless charging system according to an embodiment of the present application. Figure 5 As shown, the wireless charging system includes a wireless charging transmitting circuit, a wireless charging receiving circuit and a key self-locking circuit.

[0066] Specifically, if Figure 5 As shown, the wireless charging transmission circuit includes a chip XKT510 and a coil L3. L3 is connected between a 12V power supply and the OUT terminal of XKT510, and is used to convert the current flowing through coil L3 into electromagnetic waves for wireless transmission. In some preferred embodiments, coil L3 has a wire diameter of 0.5mm, an outer diameter of 38mm, an inner diameter of 30mm, a thickness of 1.8mm, and an inductance of 30uH.

[0067] like Figure 5 As shown, the wireless charging transmission circuit also includes capacitors C30, C31, and C32, and resistors R43, R44, and R45. The above-mentioned implementation method of building a wireless charging transmission circuit using a control chip and discrete components is well known to those skilled in the art and will not be repeated here.

[0068] Specifically, if Figure 5 As shown, the wireless charging receiving circuit includes chip T3168, coil L2, and inductor L1. L2 is connected between the IN terminal of chip T3168 and the ground terminal, generating an induced electromotive force by inducing electromagnetic waves. L1 is connected between the OUT terminal of chip 3168 and the output terminal. In some preferred embodiments, L2 has a coil wire diameter of 0.5mm, an outer diameter of 38mm, an inner diameter of 30mm, a thickness of 1.8mm, and an inductance of 30uH. L1 uses a 22uH inductor that matches the coil and is packaged in a CD54.

[0069] like Figure 5As shown, the wireless charging receiving circuit also includes capacitors C4 and C10, a resistor R1 and diodes D1, D3, D2 and D4. The above-mentioned implementation method of building a wireless charging transmitting circuit using a control chip and discrete components is well known to those skilled in the art and will not be repeated here.

[0070] Further, if Figure 5 As shown, an LED 3 is connected in series between the power supply terminal and the ground terminal of the wireless charging receiving circuit to display the charging status of the wireless charging receiving circuit.

[0071] Specifically, if Figure 5 As shown, a key self-locking circuit is connected between the 5V power supply terminal and the output terminal VIN of the wireless charging receiving circuit. The key self-locking circuit is a low-power bistable self-locking key circuit provided in this application. Its implementation method and working principle have been described in detail above and will not be repeated here.

[0072] The above is a detailed introduction to the specific implementation methods of the present application. For those skilled in the art, several improvements and modifications can be made to the present application without departing from the principles of the present application. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A low-power bistable self-locking key circuit, characterized by: Includes buttons, switch modules, drive capacitors, voltage divider resistors and two switching modules; The key connects two separated contacts when pressed; The first end of each switching module is connected to the power supply end through a pull-up resistor, and the second end of each switching module is connected to the ground end; The first end of each switching module is also connected to the enable end of another switching module, and the enable end is used to control the on / off state of the corresponding switching module; The first end of each switching module is further connected to a contact, the voltage divider resistor is connected in series between the first end of one of the switching modules and the contact connected thereto, and the driving capacitor is connected in series between the contact and the ground terminal, wherein a ratio of a resistance value of the voltage divider resistor to a resistance value of the pull-up resistor is greater than or equal to 10, and a capacitance range of the driving capacitor is [4.7 nF, 27 nF]. The switch module is connected in series between the power supply path of the power supply end and the output end, and the enable end thereof is connected to the first end of one of the switch modules for controlling the on / off state of the power supply path.

2. The low-power bistable self-locking key circuit according to claim 1, characterized in that: It also includes a current limiting resistor, which is connected in series between a contact point not connected to the driving capacitor and a first end of the switching module connected to the contact point.

3. The low-power bistable self-locking key circuit according to claim 2, characterized in that: The resistance of the pull-up resistor is much greater than the resistance of the current-limiting resistor.

4. The low-power bistable self-locking key circuit according to any one of claims 1 to 3, characterized in that: The switching module is an NMOS tube, wherein the G pole is an enable terminal, the D pole is a first terminal, and the S pole is a second terminal; and The switch module is a PMOS tube, wherein the G pole is an enable terminal, the D pole is a first terminal, and the S pole is a second terminal.

5. A wireless charging system comprising a wireless charging transmitting circuit, a wireless charging receiving circuit, and a key self-locking circuit. The wireless charging receiving circuit converts electromagnetic waves emitted by the wireless charging transmitting circuit into electrical signals at a power supply end through energy coupling, and charges a load through an output end. The key self-locking circuit is connected to the wireless charging receiving circuit or the wireless charging transmitting circuit, characterized in that: The key self-locking circuit is a low-power bistable self-locking key circuit according to any one of claims 1 to 4.

6. The wireless charging system according to claim 5, wherein: An LED light is also connected in series between the power supply end and the ground end of the wireless charging receiving circuit to display the charging status of the wireless charging receiving circuit.

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