Patent Publication Number: US-2023163756-A1

Title: Switch circuit and electric device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of International Application No. PCT/CN2020/103037, filed on Jul. 20, 2020, which claims priority to Chinese Patent Application No. 202021236176.4, filed on Jun. 29, 2020, and claims priority to Chinese Patent Application No. 202010605084.7, filed on Jun. 29, 2020 the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the field of circuits, and particularly to a switch circuit and an electric device. 
     BACKGROUND 
     For a circuit of an electronic device, a switch element is generally provided between a power-supply terminal and a load terminal, and an electrical connection between the power-supply terminal and the load terminal is turned on or turned off by controlling switching of a turned-on state and a turned-off state of the switch element. 
     The existing switch element generally includes transistors, such as metal oxide semiconductor (MOS) transistors, etc. However, due to instantaneous impact of a current with a load connected, the time for the transistor to be switched between the turned-on state and the turned-off state is relatively long, which causes the transistor to work in a linear region or be burnt out. As a result, reliability of the entire electronic device is reduced. 
     SUMMARY 
     Implementations of the disclosure provide a switch circuit. The switch circuit includes a control unit, a driving unit, a voltage sudden-change unit, and a connection unit. The connection unit is electrically coupled between a power-supply device and a load, and is configured to turn on or turn off an electrical connection between the power-supply device and the load. The control unit is electrically coupled with the driving unit, the driving unit is further electrically coupled with the connection unit, and the control unit is configured to output an enable signal to the driving unit to control the driving unit to output or stop outputting a driving signal to the connection unit, where the driving signal allows to turn on the connection unit. The voltage sudden-change unit is electrically coupled with a driving node between the driving unit and the connection unit, the control unit is further electrically coupled with the voltage sudden-change unit, and the control unit is further configured to output the enable signal to the voltage sudden-change unit to control the voltage sudden-change unit to generate and output a voltage sudden-change signal to the driving node, where the voltage sudden-change signal allows to control a potential at the driving node to experience sudden change when the driving unit stops outputting the driving signal, to make the connection unit be switched to a turned-off state from a turned-on state quickly when no driving signal is received. 
     Implementations of the disclosure provide an electric device. The electric device includes a power-supply device, a load, and the above switch circuit. The power-supply device is electrically coupled with the load via the switch circuit, and the power-supply device is configured to output a power signal to the load when the switch circuit is in the turned-on state. The load is configured to receive the power signal when the switch circuit is in the turned-on state and operate according to the power signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe technical solutions of implementations of the disclosure more clearly, the following will give a brief description of accompanying drawings used for describing the implementations. Apparently, accompanying drawings described below are merely some implementations. Those of ordinary skill in the art can also obtain other accompanying drawings based on the accompanying drawings described below without creative efforts. 
         FIG.  1    is a schematic structural diagram illustrating an electric device according to implementations. 
         FIG.  2    is a schematic structural diagram illustrating a switch circuit of the electric device illustrated in  FIG.  1    according to implementations. 
         FIG.  3    is a schematic structural diagram illustrating a detailed circuit of the switch circuit illustrated in  FIG.  2    according to implementations. 
     
    
    
     DETAILED DESCRIPTION 
     Technical solutions of implementations of the disclosure will be described below in a clear and comprehensive manner with reference to accompanying drawings intended for the implementations. It is evident that the implementations described herein constitute merely some rather than all implementations of the disclosure, and that those of ordinary skill in the art will be able to derive other implementations based on these implementations without making creative efforts, which all such derived implementations shall all fall in the protection scope of the disclosure. 
     Hereinafter, implementations are described with reference to the accompanying drawings to illustrate exemplary implementations of the disclosure. The directional terms of the disclosure such as “up”, “down”, “front”, “rear”, “left”, “right”, “inner”, “outer”, “side”, and the like describe directions illustrated in the accompanying drawings, which are intended to facilitate a better and clear description and understanding of the disclosure, rather than indicating or implying that a certain device or element must have a specific orientation or must be constructed and operated in a specific orientation, and therefore, the directional terms should not be understood as a limitation of the disclosure. In addition, in implementations of the disclosure, it is appreciated that the terms “dispose”, “interconnect”, “connect”, and “fix” should be understood in a broad sense unless otherwise specified and limited. For example, the terms “interconnect” and “connect” may refer to fixedly connect, detachably connect, or integrally connect. The terms “interconnect” and “connect” may also refer to mechanically connect. The terms “interconnect” and “connect” may also refer to directly connect, indirectly connect through an intermediate medium, intercommunicate interiors of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the implementations of the disclosure can be understood according to specific situations. 
     In the disclosure, the terms “of”, “corresponding”, and “relevant” can be interchangeable in some cases. It is appreciated that the meanings of these terms are the same, unless otherwise stated. In addition, in order to facilitate a clear description of the technical solutions of the implementations of the disclosure, in the implementations of the disclosure, the terms such as “first” and “second” are used to distinguish same or similar items with substantially a same function and effect. Those skilled in the art can understand that the terms such as “first” and “second” are not used to limit the number of the items and the order of execution, nor are these terms used to limit the items to be different. In addition, the terms “include”, “comprise”, and “have” as well as variations thereof are intended to cover non-exclusive inclusion. 
       FIG.  1    is a schematic structural diagram illustrating an electric device  10  according to implementations. As illustrated in  FIG.  1   , the electric device  10  includes a power-supply device  100 , a switch circuit  200 , and a load  300 . The power-supply device  100  is electrically coupled with the load  300  via the switch circuit  200 , and is configured to transmit a power signal to the load  300  when the switch circuit  200  is in a turned-on state. 
     In implementations of the disclosure, the power-supply device  100  may include a storage battery. The storage battery may be a nickel-cadmium battery, a lithium polymer battery, or other batteries that can supply a power signal to the load  300 , which is not limited in the disclosure. 
     In implementations of the disclosure, the power-supply device  100  may include a generator powered by combustible energy sources. The combustible energy sources may include natural fuels (e.g., hydrogen, gasoline, and natural gas, etc.) and man-made fuels, which is not limited in the disclosure. 
     In implementations of the disclosure, the power-supply device  100  may include a storage battery and a generator. The battery and the generator cooperate to supply power, to supply a power signal to the load  300 . 
     The load  300  is configured to receive the power signal outputted by the power-supply device, to drive internal components to operate according to the power signal. 
     In implementations of the disclosure, the load  300  is a device that can operate under action of an electric signal. The load  300  may be an electric ignition device, a drive motor, or other electric drive devices, which is not limited in the disclosure. 
     The switch circuit  200  is electrically coupled between the power-supply device  100  and the load  300 . The switch circuit  200  is configured to transmit a power signal outputted by the power-supply device  100  to the load  300  when the switch circuit  200  is in a turned-on state. The switch circuit  200  is further configured to stop transmitting the power signal to the load  300  when the switch circuit  200  is in a turned-off state. 
     In implementations of the disclosure, the electric device  10  supplies, with the power-supply device  100 , a power signal to the load  300 , and the load  300  drives internal electronic components thereof to operate according to the power signal. Moreover, the switch circuit  200  coupled between the power-supply device  100  and the load  300  can control transmission of the power signal outputted by the power-supply device  100 , to supply power to or power off the load  300 . 
       FIG.  2    is a schematic structural diagram illustrating a switch circuit of the electric device illustrated in  FIG.  1   . As illustrated in  FIG.  2   , the switch circuit  200  includes a control unit  201 , a driving unit  202 , a voltage sudden-change unit  203 , and a connection unit  204 . The connection unit  204  is electrically coupled between the power-supply device  100  and the load  300 , and is configured to turn on or turn off an electrical connection between the power-supply device  100  and the load  300 . 
     The control unit  201  is electrically coupled with the driving unit  202 , and the driving unit  202  is further electrically coupled with the connection unit  204 . The control unit  201  is configured to output an enable signal to the driving unit  202  to control the driving unit  202  to output or stop outputting a driving signal to the connection unit  204 , where the driving signal allows to turn on the connection unit  204 . The connection unit  204  is in a turned-on state when the driving signal is received, and the connection unit  204  is in a turned-off state when no driving signal is received. 
     A driving node B is formed between the driving unit  202  and the connection unit  204 . The voltage sudden-change unit  203  is electrically coupled with the driving node B. 
     The control unit  201  is further electrically coupled with the voltage sudden-change unit  203 . The control unit  201  is further configured to output the enable signal to the voltage sudden-change unit  203 , to control the voltage sudden-change unit  203  to generate and output a voltage sudden-change signal to the driving node B. The voltage sudden-change signal allows to control a potential at the driving node B to experience sudden change when the driving unit  202  stops outputting the driving signal, to make the connection unit  204  be switched to the turned-off state from the turned-on state quickly when no driving signal is received. 
     In the related art, the connection unit  204  is in a turned-on state when a driving signal is received, and the connection unit  204  is in a turned-off state when no driving signal is received. However, power MOS transistors of the connection unit  204  generally have a parasitic capacitance. In the case that no driving signal is received by the power MOS transistors, the power MOS transistors remain in the turned-on state due to residual charges in the parasitic capacitance, and the residual charges are discharged until the power MOS transistors cannot be turned on. As a result, when the driving unit  202  stops outputting the driving signal, the power MOS transistors work in a linear region due to slow discharge of the parasitic capacitance, which increases the risk of burning out the power MOS transistors and causes the connection unit  204  to be unable to switch to the turned-off state, thereby reducing safety and reliability of the switch circuit  200 . 
     In the disclosure, the voltage sudden-change unit  203  of the switch circuit  200  can generate the voltage sudden-change signal to control the potential at the driving node B to experience sudden change when the driving unit  202  stops outputting the driving signal, which causes the parasitic capacitance of the power MOS transistors of the connection unit  204  to be discharged to zero quickly, so that the power MOS transistors are switched to the turned-off state quickly. In this way, it is possible to prevent the power MOS transistors from being burnt out due to working in the linear region, thereby improving reliability of the switch circuit  200  during operation. 
     In implementations of the disclosure, the control unit  201  may be a microcontroller unit (MCU), a field programmable gate array (FPGA), or other integrated circuits capable of controlling subsequent units, which is not limited in the disclosure. 
     In implementations of the disclosure, the enable signal outputted by the control unit  201  includes a first voltage signal and a second voltage signal. The first voltage signal allows to control the driving unit  202  to output a driving signal, to make the connection unit  204  enter the turned-on state. In this case, the switch circuit  200  is in the turned-on state, and the power-supply device  100  can be electrically coupled with the load  300  via the switch circuit  200 . 
     The second voltage signal allows to control the driving unit  202  to stop outputting the driving signal to make the connection unit  204  enter the turned-off state, and further allows to control the voltage sudden-change unit  203  to generate and output a voltage sudden-change signal to control a potential at the driving node B to experience sudden change when the driving unit  202  stops outputting the driving signal, so that the connection unit  204  is switched to the turned-off state from the turned-on state quickly. In this case, the switch circuit  200  is in the turned-off state, and so the power-supply device  100  is not allowed to be electrically coupled with load  300  via the switch circuit. 
     Before the driving unit  202  stops outputting the driving signal, the potential at the driving node B is at high level due to the driving signal. In implementations of the disclosure, controlling the potential at the driving node B to experience sudden change herein refers to that the voltage sudden-change unit  203  pulls the potential at the driving node B down quickly when the driving unit  202  stops outputting the driving signal, that is, the potential at the driving node B is switched to a low level from a high level suddenly. In this way, a parasitic capacitance of power MOS transistors of the connection unit  204  is discharged to zero quickly, to make the power MOS transistors be switched to the turned-off state quickly. As such, the connection unit  204  can enter the turned-off state quickly. 
       FIG.  3    is a schematic structural diagram illustrating a detailed circuit of the switch circuit illustrated in  FIG.  2    according to implementations. As illustrated in  FIG.  3   , the control unit  201  is electrically coupled with a control node A. The control unit  201  is configured to output an enable signal to the control node A, and the control node A is configured to transmit the enable signal to the driving unit  202  and the voltage sudden-change unit  203 . 
     In one implementation, the driving unit  202  includes a first input terminal IN 1 , a first transistor Q 1 , and a second transistor Q 2 . The first transistor Q 1  for example is a P-type MOS transistor, and the second transistor Q 2  for example is an NPN transistor. The first input terminal IN 1  is configured to receive the driving signal inputted. A source of the first transistor Q 1  is electrically coupled with the first input terminal IN 1 . A drain of the first transistor Q 1  is electrically coupled with the driving node B. A gate of the first transistor Q 1  is electrically coupled with the source of the first transistor Q 1  via a first resistor R 1 , and is electrically coupled with a collector of the second transistor Q 2  via a second resistor R 2 . An emitter of the second transistor Q 2  is electrically coupled with a ground terminal GND. A base of the second transistor Q 2  is electrically coupled with the control node A. 
     In implementations of the disclosure, the second transistor Q 2  of the driving unit  202  is configured to receive the enable signal transmitted by the control node A to make the second transistor Q 2  be turned on or turned off. Specifically, in the case that the enable signal at the control node A is at high level, the second transistor Q 2  is turned on under action of the enable signal. In this case, the gate of the first transistor Q 1  is electrically coupled with the ground terminal GND via the second resistor R 2  and the turned-on second transistor Q 2 , to make a potential at the gate of the first transistor Q 1  be pulled down. As a result, the first transistor Q 1  is turned on, and so the driving signal received via the first input terminal IN 1  can be transmitted to the driving node B, to make the connection unit  204  be in the turned-on state. In the case that the enable signal at the control node A is at low level, the second transistor Q 2  is turned off under action of the enable signal. In this case, the gate of the first transistor Q 1  is coupled with the first input terminal IN 1  via the first resistor R 1 , to make the potential at the gate of the first transistor Q 1  be pulled up. As a result, the first transistor Q 1  is turned off, and so the driving signal cannot continue to be transmitted to the driving node B via the second transistor Q 2 , to make the connection unit  204  be in the turned-off state. 
     In one implementation, the voltage sudden-change unit  203  includes a second input terminal IN 2 , a third transistor Q 3 , a first capacitor C 1 , a first Zener diode D 1 , and a fourth transistor Q 4 . The third transistor Q 3  for example is an NPN transistor, and the fourth transistor Q 4  for example is an N-type MOS transistor. The second input terminal IN 2  is electrically coupled with a collector of the third transistor Q 3  and a first capacitor node C of the first capacitor C 1  via a third resistor R 3 . The second input terminal IN 2  is configured to receive a charging voltage inputted. A second capacitor node D of the first capacitor C 1  is electrically coupled with a ground terminal GND via a fourth resistor R 4 . A base of the third transistor Q 3  is electrically coupled with the control node A. An emitter of the third transistor Q 3  is electrically coupled with the ground terminal GND. A collector of the third transistor Q 3  is electrically coupled with the first capacitor node C of the first capacitor C 1 . An anode of the first diode D 1  is electrically coupled with the driving node B. A cathode of the first diode D 1  is electrically coupled with a drain of the fourth transistor Q 4  via a fifth resistor R 5 . A gate of the fourth transistor Q 4  is electrically coupled with the second capacitor node D. A source of the fourth transistor Q 4  is electrically coupled with the ground terminal GND. The gate of the fourth transistor Q 4  is further electrically coupled with the source of the fourth transistor Q 4  via the fourth resistor R 4 . 
     In implementations of the disclosure, the third transistor Q 3  of the voltage sudden-change unit  203  is configured to receive the enable signal transmitted by the control node A, to make the third transistor Q 3  be turned on or turned off. The fourth transistor Q 4  is switched between the turned-on state and the turned-off state according to a potential at the second capacitor node D. 
     When in use, in an initial state, the control unit  201  outputs a low-level enable signal, the third transistor Q 3  is turned off under action of the enable signal, to form a current loop including the second input terminal IN 2 , the third resistor R 3 , the first capacitor C l , and the four resistors R 4 , and the ground terminal GND, so that the first capacitor C 1  is charged due to receiving a charging voltage of the second input terminal IN 2 . In this case, the first capacitor node C is coupled with the second input terminal IN 2  via the third resistor R 3 , and a potential at the first capacitor node C is at high level due to a high-level signal inputted via the second input terminal IN 2  and a maintained action of the first capacitor C 1 . The second capacitor node D is electrically coupled with the ground terminal GND via the fourth resistor R 4 , to make the second capacitor node D be at low level, and so the fourth transistor Q 4  is turned off. After charging, a voltage difference across the first capacitor C 1  is relatively high. 
     When operating, in the case that the control unit  201  outputs a high-level enable signal, as stated above, the driving signal inputted via the first input terminal IN 1  can be transmitted to the driving node B, that is, the driving node B is at high level, and so the connection unit  204  is in the turned-on state. The third transistor Q 3  is turned on under action of the enable signal. The first capacitor node C is electrically coupled with the ground terminal GND via the turned-on third transistor Q 3 , so that a potential at the first capacitor node C is switched to a low-level state from a high-level state suddenly. Since a voltage difference across the first capacitor C 1  is relatively high, and the first capacitor C 1  does not allow the voltage difference across the first capacitor C 1  to experience sudden change due to capacitance characteristics, a potential at the second capacitor node D is switched to a high-level state from a low-level state, to keep the voltage difference across the first capacitor C 1  unchanged, and so the fourth transistor Q 4  is turned on. Since the first capacitor C 1  is electrically coupled with the ground terminal GND via the fourth resistor R 4 , the first capacitor C 1  is discharged gradually, so that the potential at the second capacitor node D decreases gradually. The first capacitor C 1  is discharged until the potential at the second capacitor node D is lower than a turn-on voltage Vgs(th) of the fourth transistor Q 4 . As a result, the fourth transistor Q 4  is turned off. 
     After discharging, the voltage difference across the first capacitor C 1  is relatively low. 
     When the fourth transistor Q 4  is in the turned-on state or the turned-off state, the connection unit  204  remains in the turned-on state due to the driving node B receiving the driving voltage. 
     When the control unit  201  outputs a low-level enable signal, as stated above, the driving signal inputted via the first input terminal IN 1  is not allowed to be transmitted to the driving node B. The third transistor Q 3  is turned off under action of the enable signal. As a result, the first capacitor node C is disconnected from the ground terminal GND, and the first capacitor node C is electrically coupled with the second input terminal IN 2  via the third resistor R 3 , so that a potential at the first capacitor node C is switched to a high-level state from a low-level state suddenly. Since the voltage difference across the first capacitor C 1  is relatively low, and the first capacitor C 1  does not allow the voltage difference across the first capacitor C 1  to experience sudden change due to capacitance characteristic, a potential at the second capacitor node D is switched to a high-level state from a low-level state, to keep the voltage difference across the first capacitor C 1  unchanged, and so the fourth transistor Q 4  is turned on. Accordingly, residual charges in a parasitic capacitance of MOS transistors of the connection unit  204  are discharged quickly through a loop including the driving node B, the first diode D 1 , the fifth resistor R 5 , the fourth transistor Q 4 , and the ground terminal GND, so that the residual charges of the MOS transistors of the connection unit  204  are discharged to zero quickly. In this way, the MOS transistors of the connection unit  204  can be turned off quickly, and so the connection unit  204  is switched to the turned-off state from the turned-on state quickly. 
     Since the first capacitor C 1  is electrically coupled with the ground terminal GND via the fourth resistor R 4 , the first capacitor C 1  is discharged gradually, so that the potential at the second capacitor node D decreases gradually. The first capacitor C 1  is discharged until the potential at the second capacitor node D is lower than a turn-on voltage Vgs(th) of the fourth transistor Q 4 . As a result, the fourth transistor Q 4  is turned off. After the fourth transistor Q 4  is turned off, the connection unit  204  remains in the turned-off state since no driving voltage is received at the driving node B. 
     In one implementation, the connection unit  204  includes a first connection terminal J 1 , a second connection terminal J 2 , a second diode D 2 , a third diode D 3 , and multiple connection subunits. An anode of the second diode D 2  is electrically coupled with the driving node B. A cathode of the second diode D 2  is electrically coupled with the first connection terminal J 1  via a sixth resistor R 6 . The first connection terminal J 1  is configured to be coupled with one of the power-supply device  100  and the load  300 . An anode of the third diode D 3  is electrically coupled with the driving node B. A cathode of the third diode D 3  is electrically coupled with the second connection terminal J 2  via a seventh resistor R 7 . The second connection terminal J 2  is configured to be coupled with another device between the power-supply device  100  and the load  300 . 
     The multiple connection subunits are similar in structure. Hereinafter, the structure of each connection subunit is described in detail, in which one of the connection subunits of the disclosure is taken as an example. 
     The connection subunit includes a fifth transistor Q 5  and a sixth transistor Q 6 . Both the fifth transistor Q 5  and the sixth transistor Q 6  are N-type transistors. A gate of the fifth transistor Q 5  is electrically coupled with the driving node B via an eighth resistor R 8 . A source of the fifth transistor Q 5  is electrically coupled with the first connection terminal J 1 . A drain of the fifth transistor Q 5  is electrically coupled with a transmission node E. The transmission node E is configured to transmit an electrical signal between the first connection terminal J 1  and the second connection terminal J 2 . A gate of the sixth transistor Q 6  is electrically coupled with the driving node B via a ninth resistor R 9 . A source of the sixth transistor Q 6  is electrically coupled with the second connection terminal J 2 . A drain of the sixth transistor Q 6  is electrically coupled with the transmission node E. 
     In implementations of the disclosure, the connection unit  204  includes four connection subunits. The four connection subunits operate in parallel, that is, if one of the four connection subunits is damaged, the other connection subunits can still operate. Moreover, the four connection subunits operating in parallel can improve a current transmission capability of the connection unit  204 . The number of the connection subunits of the connection unit  204  may be increased or decreased according to actual needs, which is not limited in the disclosure. 
     In implementations of the disclosure, MOS transistors of the connection unit  204  are switched between the turned-on state and the turned-off state according to a potential signal at the driving node B. Specifically, in an initial state, the control unit  201  outputs a low-level enable signal, and the first transistor Q 1  is turned off under action of the enable signal. As a result, a driving signal inputted via the first input terminal IN 1  cannot be outputted to the MOS transistors of the connection unit  204  via the first transistor Q 1 , and so the MOS transistors of the connection unit  204  are in the turned-off state. When operating, the control unit  201  outputs a high-level enable signal, and so the driving signal inputted via the first input terminal IN 1  can be transmitted to the driving node B, to make the driving node B be at high level. As a result, the MOS transistors of the connection unit  204  are in the turned-on state. Accordingly, an electrical connection between the power-supply device  100  electrically coupled with the first connection terminal J 1  and the load  300  electrically coupled with the second connection terminal J 2  is turned on. When the operating is finished, the control unit outputs a low-level enable signal, and so the driving signal inputted via the first input terminal IN 1  cannot be transmitted to the driving node B. Residual charges in a parasitic capacitance of the MOS transistors of the connection unit  204  are discharged to zero by means of the voltage sudden-change unit  203  electrically coupled with the driving node B. In this way, the MOS transistors of the connection unit  204  are turned off quickly, and so the connection unit  204  is switched to the turned-off state from the turned-on state quickly. Accordingly, the electrical connection between the power-supply device  100  and the load  300  is turned off. 
     Compared to the related art, the voltage sudden-change unit  203  of the switch circuit  200  of the implementations of the disclosure can generate a voltage sudden-change signal to control a potential at the driving node B to experience sudden change when the driving unit  202  stops outputting a driving signal used for turning on the connection unit  204 , which causes a parasitic capacitance of power MOS transistors of the connection unit  204  to be discharged to zero quickly, so that the power MOS transistors are switched to the turned-off state quickly. In this way, a situation where the power MOS transistor is burnt out due to working in a linear region can be avoided, thereby improving reliability of the switch circuit  200  during operation. 
     The switch circuit and the electric device of the implementations of the disclosure have been described in detail above. While the principles and implementations of the disclosure have been described in connection with illustrative implementations, it is to be understood that foregoing implementations are only used to help understand the method and core idea of the disclosure. As will occur to those skilled in the art, the disclosure is susceptible to various modifications and changes without departing from the spirit and principle of the disclosure. Therefore, the disclosure is not limited to the disclosed implementations.