TWI819381B - Switch device - Google Patents

Abstract

A switch device includes a first circuit. The first circuit has a first end coupled between a first terminal and a second terminal. The first shunt has a second end coupled between the first terminal and the second terminal, or coupled to a third terminal. The first circuit includes a first switch and a second switch. The first switch is coupled between the first end and the second end of the first circuit, and is turned on or off according to a first control signal. The second switch is coupled to the first switch in parallel, and is turned-on or off according to a second control signal. The first switch and the second switch include transistors of the same type. In a surge current protection mode, the second switch is turned on to dissipate a surge current. The first circuit may be a shunt circuit.

Description

switchgear

The present invention relates to a switching device, and in particular to a switching device that can increase switching speed.

In the conventional technical field, in order to ensure that the switching device has a certain degree of electrostatic discharge protection capability, large-sized transistors are often provided in the shunt circuit to effectively discharge the electrostatic discharge current.

However, the large-sized transistor provided in the shunt circuit provides a large-sized parasitic capacitance during the switching process, which will cause the switching speed of the switching device to decrease and affect the performance of the signal switching speed.

The present invention provides a switching device that can improve the switching speed of the switching device and/or can enhance the discharge capability of surge current in the surge protection mode.

The switching device of the present invention includes a first circuit. The first circuit has a first end coupled between the first terminal and the second terminal, and the first circuit has a second end coupled between the first terminal and the second terminal, or coupled to the third terminal. The first circuit includes the first switch as well as a second switch. The first switch is coupled between the first end of the first circuit and the second end of the first circuit, and is turned on or off according to the first control signal. The second switch is connected in parallel with the first switch and is turned on or off according to the second control signal. The first switch and the second switch include the same type of transistor. In the surge protection mode, the second switch is turned on to discharge the surge current.

Based on the above, the present invention provides a first switch and a second switch in the switch device. In the normal mode, the first switch can be used for switching signal transmission, and the second switch can be used to improve the switching speed of the first switch. In surge protection mode, the second switch can be used to assist in venting surge current. The switching device of the present invention can increase the switching speed of the switching device, and/or can enhance the discharge capability of surge current.

101, 102, 301, 302, 900: Switching device

△t1, △t2: constant potential period

A1, A2, B1, B2: terminal

E1~E4, EC: terminal

R1~R4, RB: Resistor

SH1, SH2, 600, 601, 602: circuit

SW1~SW4, 810-1, 820-1, 810-2, 820-2, SW1A, SW1B: switch

T1~T3, T21~T2N, T31~T3M, T1A, T1B: transistor

TA: Multi-gate transistor

tP1, tP2: period

VB: base voltage

VC1~VC4: control signal

FIG. 1 is a schematic diagram of a switch device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a switch device according to another embodiment of the present invention.

FIG. 3 is a schematic diagram of a switch device according to another embodiment of the present invention.

FIG. 4 is a schematic diagram of a switch device according to another embodiment of the present invention.

FIG. 5A shows a waveform diagram of a control signal of the shunt circuit in the switching device according to the embodiment of the present invention.

FIG. 5B shows a waveform diagram of another implementation of the control signal of the shunt circuit in the switching device according to the embodiment of the present invention.

FIG. 6A illustrates an implementation of a shunt circuit in a switching device according to an embodiment of the present invention. Schematic diagram of the formula.

6B and 6C respectively illustrate schematic diagrams of other implementations of the shunt circuit in the switching device according to the embodiment of the present invention.

FIG. 7A shows an operation waveform diagram of an embodiment of the shunt circuit of the embodiment of FIG. 6A.

FIG. 7B illustrates an operation waveform diagram of another embodiment of the shunt circuit of the embodiment in FIG. 6A.

8A and 8B are schematic diagrams of other implementations of the shunt circuit in the switching device according to the embodiment of the present invention.

FIG. 9 is a schematic diagram of a switch device according to another embodiment of the present invention.

Please refer to FIGS. 1 and 2 , which are schematic diagrams of switch devices 101 and 102 according to an embodiment of the present invention.

In one embodiment, as shown in FIG. 1 , the switching device 101 includes a first circuit SH1 and a switch SW3. The first terminal A1 and the second terminal A2 of the first circuit SH1 are coupled to the current path formed between the first terminal E1 and the second terminal E2. In this embodiment, the first terminal A1 of the first circuit SH1 is coupled to the first terminal E1, and the second terminal A2 is coupled to the second terminal E2. In this embodiment, the first terminal B1 of the switch SW3 is coupled to the first terminal E1 and the first terminal A1 of the first circuit SH1, and the second terminal B2 of the switch SW3 is coupled to the third terminal E3. In another embodiment, as shown in FIG. 2 , the first terminal B1 of the switch SW3 can also be coupled to the second terminal A2 of the first circuit SH1 and Second terminal E2. In the above embodiment, the switch SW3 is turned on or off according to the control signal VC3. In a further embodiment, the switch SW3 may include a transistor T3, and the control end of the transistor T3 is used to receive the control signal VC3.

In the above description, the first circuit SH1 can be used to switch signals between the first terminal E1 and the second terminal E2, and the switch SW3 can be used for shunting. For example, when the first circuit SH1 is turned off so that the signal is not at the first terminal When transmitting between E1 and the second terminal E2, the switch SW3 is turned on. However, the present invention is not limited to this. In other embodiments, the switch SW3 can be used to switch signals between the first terminal E1 and the second terminal E2. The first circuit SH1 can be a shunt circuit, which can be used to perform when turned on. Diversion action.

Please refer to FIG. 3 and FIG. 4 below, which illustrate a schematic diagram of a switch device according to another embodiment of the present invention. The switching device 301 includes a first shunt circuit SH1 and a switch SW3. The first terminal B1 of the switch SW3 is coupled to the first terminal E1, and the second terminal B2 is coupled to the second terminal E2. In this embodiment, the first terminal A1 of the shunt circuit SH1 is coupled to the first terminal E1 and the first terminal B1 of the switch SW3 (as shown in FIG. 3 ), or is coupled to the second terminal E2 and the third terminal of the switch SW3. Two terminals B2 (as shown in Figure 4).

In one embodiment, the first terminal E1 and the second terminal E2 may be signal transceivers for receiving or transmitting signals. The third terminal E3 can be a reference voltage terminal for receiving the reference voltage, such as ground.

In one embodiment, please refer to FIGS. 1-4 , the first circuit SH1 includes a switch SW1 and a switch SW2. The first terminal of the switch SW1 is coupled to the first terminal A1 of the first circuit SH1, and the second terminal of the switch SW1 is coupled to the second terminal A2 of the first circuit SH1. The switch SW2 and the switch SW1 are coupled in parallel. The switches SW1 and SW2 are turned on or off according to the control signals VC1 and VC2 respectively. Furthermore, the switches SW1 and SW2 may include transistors T1 and T2 respectively. The first terminals of the transistors T1 and T2 are coupled to each other, and the second terminals of the transistors T1 and T2 are coupled to each other. The control terminals of transistors T1 and T2 receive control signals VC1 and VC2 respectively. In one embodiment, transistors T1 and T2 are of the same type. For example, the transistors T1 and T2 may both be N-type transistors, or both may be P-type transistors. For example, in the case of N-type transistors, the first terminal of the transistors T1 to T2 is the drain, the second terminal is the source, and the control terminal is the gate. In this embodiment, using the same type of transistors T1 and T2 can improve the switching speed without significantly increasing the manufacturing process and cost.

In one embodiment, in the normal mode of signal transmission, the conduction states of the switch SW1 and the switch SW3 may be different. For example, when the switch SW1 is on, the switch SW3 may be off, and when the switch SW1 is off, the switch SW3 may be on. Furthermore, in the normal mode, the switches SW1 and SW3 can be switched between on and off according to the control signals VC1 and VC3 respectively. As shown in Figure 1-2, when the switch SW1 is turned on, the signal can be transmitted between the first terminal E1 and the second terminal E2. When the switch SW1 is turned off, the switch SW3 can be turned on to perform branching. Or, as shown in Figure 3-4, when the switch SW3 is turned on, the signal can be transmitted between the first terminal E1 and the second terminal E2. When the switch SW3 is turned off, the switch SW1 is turned on, so that the shunt circuit SH1 can be turned on to execute Diversion.

In one embodiment, when the switching device 101 or 102 receives a surge voltage or a surge current, such as when an electrostatic discharge occurs, the switching device 101 or 102 can enter Surge protection mode. In the surge protection mode, the switch SW2 can be turned on according to the control signal VC2 to assist in discharging the surge current. Furthermore, in the surge protection mode, the switch SW1 and the switch SW3 can also be turned on to discharge the surge current. Furthermore, in the surge protection mode, the transistor T1 of the switch SW1, the transistor T2 of the switch SW2, and the transistor T3 of the switch SW3 can all be turned on to discharge the surge current. In this embodiment, compared with a circuit in which only switches SW1 and SW3 are provided, the transistor T2 of switch SW2 can increase the ability to discharge surge current in the surge protection mode.

In particular, in the first embodiment, the transistor T2 of the switch SW2 can remain off in the normal mode (not shown), and the transistors T1 and T3 can be switched between on and off to switch signal transmission. In this embodiment, the size of the transistor T2 may be larger than, smaller than, or equal to the size of the transistor T1 to assist in dissipating the surge current. Alternatively, in the second embodiment, the transistor T2 switches between on and off in the normal mode, and the size of the transistor T2 can be smaller than the size of the transistor T1 to improve the switching speed of the transistor T1. It should be noted that in the first and second embodiments, as mentioned above, when, for example, electrostatic discharge occurs and the surge protection mode is entered, the transistor T2 is turned on.

The following takes FIG. 3 as an example to further describe the operation of the transistor T2 in the second embodiment.

Reference may be made simultaneously to FIG. 3 , FIG. 5A and FIG. 5B , wherein FIG. 5A and FIG. 5B illustrate an implementation waveform diagram of the control signals VC1 and VC2 of the shunt circuit SH1 in the switching device according to the embodiment of the present invention.

In FIG. 5A, during the first period tP1, the transistor T1 can be maintained to be turned on according to the control signal VC1 with a relatively high level, and in the second period tP2, the transistor T1 can be maintained according to the control signal VC1 with a relatively low level. The control signal VC1 remains cut off. At the starting point of the first period tP1, the transistor T1 changes from off to on, and the transistor T2 can be turned on during the constant potential period Δt1 according to a high voltage pulse on the control signal VC2. At the starting point of the second period tP2, the transistor T1 changes from on to off, and the transistor T2 can be turned on during the constant potential period Δt2 according to another high voltage pulse wave of the control signal VC2. During the constant potential periods Δt1 and Δt2, the transistor T2 is turned on, thereby setting both ends of the transistor T1 to the same voltage value. In this embodiment, since the size of the transistor T2 is smaller than the size of the transistor T1, the transistor T2 can have a faster switching speed than the transistor T1. By setting the two ends of the transistor T1 to the same voltage value through the rapid conduction action of the transistor T2, the gate-source voltage and gate-drain voltage of the transistor T1 can quickly reach the desired value, thereby making the transistor T1 T1 quickly enters the on or off state. Therefore, the switching speed of the transistor T1 between on and off can be increased through the transistor T2.

In FIG. 5B , the operation of the transistor T1 is similar to that shown in FIG. 5A , and will not be described again. The difference is that during the certain potential period Δt1 before the starting point of the first period tP1 (before the start), the control signal VC2 can be pulled high first to turn on the transistor T2 and maintain the constant potential period Δt1 for the length of time. Then, during the first period tP1, the voltage value of the control signal VC2 maintains a high level, so that the transistor T2 continues to be turned on. Starting from the starting point of the second period tP2, the transistor T1 changes from on to off, and during a certain potential period Δt2, the voltage value of the control signal VC2 is maintained at a high level, causing the current The transistor T2 remains turned on until the constant potential period Δt2 ends, and the voltage value of the control signal VC2 is pulled down, so that the transistor T2 is turned off. During the constant potential periods Δt1 and Δt2, the transistor T2 is turned on, thereby setting both ends of the transistor T1 to the same voltage value. Please refer to Figure 3. During the first period tP1, the transistors T1 and T2 can be turned on at the same time and can perform the shunting action synchronously. In the embodiment shown in 5B, the starting point of the constant potential period Δt1 is earlier than the starting point of the first period tP1, and the starting point of the constant potential period Δt2 overlaps with the starting point of the second period tP2.

5A and 5B illustrate the states of transistors T1 and T2 in the normal mode in the second embodiment. During the first period tP1 and/or the second period tP2, electrostatic discharge may occur, the switching device may enter the surge protection mode, and the three transistors T1, T2, and T3 may be turned on at the same time to discharge the surge current.

In the above embodiment, the time length of the constant potential period Δt1 is less than the time length of the first period tP1, and the time length of the constant potential period Δt2 is less than the time length of the second period tP2. In further embodiments, the transistor T2 may be turned on only during any one of the constant potential periods Δt1 and Δt2, and the present invention is not limited to this.

Please refer to FIGS. 6A-6C below. FIGS. 6A-6C are schematic diagrams of implementations of the shunt circuit 600 in the switching device according to the embodiment of the present invention. The shunt circuit 600 includes switches SW1, SW2, and SW4. The switches SW1, SW2, and SW4 are connected in parallel between the first terminal A1 and the second terminal A2 of the shunt circuit 600. The switches SW1, SW2, and SW4 may include transistors T1, T2, and T4, respectively. The first terminals of the transistors T1, T2, and T4 are jointly coupled to the first terminal A1 of the shunt circuit 600, and the second terminals of the transistors T1, T2, and T4 are jointly coupled to the second terminal A2 of the shunt circuit 600. The control terminals of transistors T1, T2, and T4 receive control signals VC1, VC2, and VC4 respectively. The transistors T1, T2, and T4 are turned on or off according to the control signals VC1, VC2, and VC4 respectively.

In particular, in the third embodiment, in the normal mode, the transistor T1 can be switched between on and off to switch signal transmission, and the transistor T2 can be switched between on and off to improve the transistor. At the switching speed of T1, transistor T4 can remain off (not shown). When, for example, electrostatic discharge occurs and the device enters the surge protection mode, the transistor T4 is turned on to discharge the surge current. Furthermore, in the surge protection mode, the transistors T1-T4 can all be turned on to discharge the surge current. In this embodiment, the size of the transistor T2 may be smaller than the size of the transistor T1.

Regarding the operation details of this embodiment, reference can be made simultaneously to FIG. 6A , FIG. 7A , and FIG. 7B , wherein FIGS. 7A and 7B illustrate an operation waveform diagram of an embodiment of the shunt circuit 600 in the embodiment of FIG. 6A . In this embodiment, in the normal mode, the timing actions of the transistors T1 and T2 are similar to those shown in FIGS. 5A and 5B and will not be described again. The difference is that compared to Figures 5A and 5B, a switch SW4 is also provided, which includes a transistor T4. In the normal mode as shown in Figures 7A and 7B, whether in the first period tP1 or the second period tP2, The transistor T4 is maintained in an off state according to the control signal VC4 which is always at a low voltage. On the other hand, during the first period tP1 and/or the second period tP2, electrostatic discharge may occur, the switching device enters the surge protection mode, and the three transistors T1, T2, and T4 may be turned on at the same time to discharge the surge current.

In some embodiments, the size of the transistor T2 may be smaller than the size of the transistor T1 , so the transistor T2 may have a faster switching speed compared to the transistor T1 . Through the rapid conduction action of the transistor T2, the transistor T1 can quickly enter the conduction or cutoff state. Therefore, the switching speed of the transistor T1 between on and off can be increased through the transistor T2. In further embodiments, the size of the transistor T4 can be larger than the size of the transistor T1 . Therefore, in the surge protection mode, the transistor T4 can provide a larger current dissipation capability, thereby improving the reliability of the switching device. However, the present invention is not limited to this. In other embodiments, the size of the transistor T4 may also be selected to be equal to or smaller than the size of the transistor T1 depending on factors such as space size. In this case, since transistors T1, T2, and T4 can all be turned on in the surge protection mode, T4 can provide auxiliary current dissipation capability without causing significant cost increase.

Please refer to FIGS. 6B and 6C , which respectively illustrate schematic diagrams of other implementations of the shunt circuit 600 in the switching device according to the embodiment of the present invention.

In FIG. 6B , the shunt circuit 601 includes transistors T1, T2, and T4 and resistors R1, R2, and R4. The first terminals of the transistors T1, T2, and T4 are coupled to each other to the first terminal A1 of the shunt circuit, and the second terminals of the transistors T1, T2, and T4 are coupled to each other to the second terminal A2 of the shunt circuit. The control terminals of the transistors T1, T2, and T4 are respectively coupled to one terminal of the resistors R1, R2, and R4. The other terminals of the resistors R1, R2, and R4 receive the control signals VC1, VC2, and VC4 respectively. In addition, the transistors T1, T2, and T4 respectively have respective substrates, and these substrates are coupled to each other through wires. The respective substrates of the transistors T1, T2, and T4 can receive the substrate voltage VB through the common resistor RB.

In FIG. 6C, the transistors T1, T2, and T4 may share the same substrate. For example, the shunt circuit 602 may include a multi-gate transistor TA. The multiple gates of the multi-gate transistor TA are respectively coupled to resistors R1, R2, and R4, and are respectively connected through the resistors R1, R2, and R4. R1, R2, and R4 receive control signals VC1, VC2, and VC4. The first terminal of the multi-gate transistor TA is coupled to the first terminal A1 of the shunt circuit 602 , and the second terminal of the multi-gate transistor TA is coupled to the second terminal A2 of the shunt circuit 602 . The base of the multi-gate transistor TA receives the base voltage VB through the resistor RB.

In some implementations, the transistors T1, T2, and T4 may all be N-type transistors, or they may all be P-type transistors. For example, in the case of N-type transistors, the first terminals of the transistors T1, T2, and T4 may be drain electrodes, the second terminals may be source electrodes, and the control terminals may be gate electrodes respectively. Please refer to FIGS. 8A and 8B , which respectively illustrate schematic diagrams of other implementations of the shunt circuits 801 and 802 in the switching device according to the embodiment of the present invention.

In FIG. 8A , the shunt circuit 801 includes a switch 810-1 and a switch 820-1, and the switch 810-1 and the switch 820-1 are coupled to each other in parallel. Furthermore, the switch 810-1 includes a plurality of transistors T11~T1N, and the switch 820-1 includes a plurality of transistors T21~T2M, where N and M are integers greater than 1. In the switch 810-1, the transistors T11~T1N are connected in series between the first terminal A1 and the second terminal A2. In the switch 820-1, the transistors T21~T2M are connected in series between the first terminal A1 and the second terminal A2. In this embodiment, the number of transistors T11 to T1N may be equal to the number of transistors T21 to T2M, that is, N=M. However, the present invention is not limited thereto. In other embodiments, N may also be different from M. For example, in FIG. 8B , the switch 810-2 includes transistors T11 to T13, and the switch 820-2 includes transistors T21 and T22. That is, N=3, and M=2.

In some embodiments, the control terminals of transistors T11~T1N can receive phase The same control signal VC1 can be turned on or off at the same time. The control terminals of the transistors T21 ~ T2M can receive the same another control signal VC2 to be turned on or off at the same time. In this embodiment, the on and off actions of switch 810-1 are similar to the on and off actions of switch SW1 in the embodiment of Figures 1 to 4, and the on and off actions of switch 820-1 are similar to those of Figures 1 to 4. The turn-on and turn-off actions of switch SW2 in the example are similar and will not be described in detail here. In this embodiment, the transistors T11 to T1N may be the same type of transistors, for example, N-type transistors. The transistors T21~T2M may be the same type of transistors, for example, N-type transistors.

Please refer to FIG. 9 , which is a schematic diagram of a switch device according to another embodiment of the present invention. The switching device 900 includes shunt circuits SH1 and SH2, and switches SW1A and SW1B. One end of the shunt circuit SH1 is coupled to the first terminal E1, and the other end is coupled to the third terminal E3. One end of the switch SW1A is coupled to the first terminal E1, and the other end is coupled to the common terminal EC. One end of the switch SW1B is coupled to the common terminal EC, and the other end is coupled to the second terminal E2. One end of the shunt circuit SH2 is coupled to the second terminal E2, and the other end is coupled to the fourth terminal E4. The shunt circuits SH1 and SH2 can be implemented using any of the shunt circuits in the aforementioned embodiments. The circuit structures of the shunt circuits SH1 and SH2 may be the same or different, and the present invention does not limit this.

In this embodiment, the first terminal E1, the second terminal E2 and the common terminal EC are signal transceiver terminals, and the third terminal E3 and the fourth terminal E4 are reference voltage terminals, such as ground. Furthermore, the switch SW1A may include a transistor T1A, and the switch SW1B may include a transistor T1B. The switches SW1A and SW1B are turned on or off according to the control signals VC1A and VC1B respectively.

In the normal mode, the on or off states of switches SW1A and SW1B can be reversed. For example, in the normal mode, when the switch SW1A is turned on, the shunt circuit SH1 does not perform current shunting action. At this time, the switch SW1B can be turned off, and the shunt circuit SH2 is activated to perform the current shunting action. When the switch SW1A is turned off, the shunt circuit SH1 is activated to perform a current shunting action. At this time, the switch SW1B can be turned on, and the shunt circuit SH2 does not perform current shunting action.

In the surge protection mode, at least one of the shunt circuits SH1 and SH2 can be activated and used to discharge the surge current. Furthermore, at least one of the switches SW1A and SW1B can be activated and used to discharge the surge current.

To sum up, the present invention provides a first switch and a second switch in the switch device. In the normal mode, the first switch can be used for switching signal transmission, and the second switch can be used to improve the switching speed of the first switch. In surge protection mode, the second switch can be used to assist in venting surge current. Furthermore, in the present invention, a first switch, a second switch and a fourth switch are provided in the switch device. In the normal mode, the first switch can be used to switch signal transmission, the second switch can be used to improve the switching speed of the first switch, and the fourth switch is turned off. In the surge protection mode, the second switch and the fourth switch can be used to assist in venting the surge current. The switching device of the present invention can increase the switching speed of the switching device, and/or can enhance the discharge capability of surge current.

301: Switching device

A1, A2, B1, B2: terminal

E1, E2, E3: terminal

SH1: first circuit

SW1, SW2, SW3: switch

T1~T3: transistor

VC1~VC3: control signal

Claims (19)

A switching device includes: a first circuit, a first terminal of the first circuit is coupled between a first terminal and a second terminal, and a second terminal of the first circuit is coupled to the first terminal. Between the terminal and the second terminal, or coupled to a third terminal, the first circuit includes: a first switch, the first end of the first switch is coupled to the first end of the first circuit, and the first end of the first switch is coupled to the first end of the first circuit. The second end of a switch is coupled to the second end of the first circuit, the first switch is turned on or off according to a first control signal; and a second switch is connected in parallel with the first switch, according to a first control signal. The two control signals are turned on or off, wherein the first switch and the second switch include the same type of transistor, and wherein, in a surge protection mode, the second switch is turned on to discharge a surge current, Wherein, the first end of the first circuit is coupled between the first terminal and the second terminal, and the second end of the first circuit is coupled to the third terminal; wherein the switching device further includes : a third switch, the first end of the third switch is coupled to the first terminal, the second end of the third switch is coupled to the second terminal, and the third switch is configured according to a third control signal. is turned on or off, where the first terminal and the second terminal are signal transceiver terminals, the third terminal is a reference voltage terminal, and in a normal mode, the conduction states of the third switch and the first switch are different. The switching device of claim 1, wherein in the normal mode, when the first switch is turned on, the third switch is turned off, and when the first switch is turned off, the third switch is turned on. The switching device of claim 1, wherein the first switch includes a first transistor, the second switch includes a second transistor, and the first terminal of the first transistor and the second transistor are coupled to each other. The second terminals of the first transistor and the second transistor are coupled to each other, and the control terminals of the first transistor and the second transistor respectively receive the first control signal and the second control signal. The first transistor is of the same type as the second transistor, the third switch includes a third transistor, and the first circuit is a first shunt circuit. The switching device of claim 3, wherein when the first transistor is switched between on and off, the second transistor is turned on to set the first terminal and the second terminal of the first transistor. voltage, wherein the size of the second transistor is smaller than the size of the first transistor. The switching device of claim 4, wherein in the normal mode, the first transistor remains on during a first period and remains off on a second period, and the second transistor remains on during the first period. The period and/or at least a certain potential period at the beginning of the second period is turned on, and the time length of the at least certain potential period is shorter than the time length of the first period and/or the second period. The switching device of claim 5, wherein the starting point of the at least certain potential period of the second transistor is earlier than the corresponding first period and/or the second period. The starting point between, or the starting point of the at least certain potential period overlaps with the corresponding starting point of the first period and/or the second period. The switching device of claim 3, wherein in the normal mode, the second transistor remains off. The switching device of claim 4, wherein the first shunt circuit further includes: a fourth switch, the fourth switch includes a fourth transistor, and the first terminal of the fourth transistor is connected to the first transistor. The first end of the fourth transistor is coupled, the second end of the fourth transistor is coupled with the second end of the first transistor, the control end of the fourth transistor receives a fourth control signal, and the fourth transistor is based on The fourth control signal can be turned on or off. In the normal mode, when the first transistor switches between on and off, the fourth transistor remains off. The switching device of claim 8, wherein in the normal mode, the first transistor remains turned on during a first period and remains turned off during a second period, wherein the second transistor remains turned on during the first period. A period and/or at least a certain potential period at the beginning of the second period is turned on, and the time length of the at least certain potential period is less than the time length of the first period and/or the second period, wherein the at least certain potential period The starting point is earlier than the starting point of the corresponding first period and/or the second period, or the starting point of the at least certain potential period is the same as the starting point of the corresponding first period and/or the second period. Points overlap. The switching device of claim 8, wherein the fourth transistor and the first transistor are the same type of transistor. The switching device of claim 10, wherein the first transistor, the second transistor and the fourth transistor are P-type transistors or N-type transistors, wherein the first transistor, the second transistor The first terminals of the crystal and the fourth transistor are respectively drains, the second terminals of the first transistor, the second transistor and the fourth transistor are respectively source electrodes, and the first transistor, the The control terminals of the second transistor and the fourth transistor are gate electrodes respectively. The switching device of claim 11, the substrates of the first transistor, the second transistor and the fourth transistor are coupled to each other, or the first transistor, the second transistor and the fourth transistor are Transistors share the same substrate. The switching device as claimed in claim 1, wherein in the surge protection mode, the first switch and the second switch are both turned on to jointly discharge the surge current. The switching device of claim 3, wherein the first transistor receives the first control signal through a first resistor, and the second transistor receives the second control signal through a second resistor. The switch device of claim 8, wherein the fourth switch receives the fourth control signal through a resistor. The switching device of claim 1, wherein the first switch includes a plurality of first transistors connected in series, and the second switch includes a plurality of second transistors connected in series, and the number of the second transistors is less than Or equal to the number of the first transistors. The switching device of claim 16, wherein each of the plurality of first transistors and one of the plurality of second transistors are coupled in parallel and aligned with each other. The switch device of claim 8, further comprising: a fifth switch coupled between a common terminal and the second terminal, wherein the common terminal is coupled between the first terminal and the second terminal; and A second shunt circuit, the first end of the second shunt circuit is coupled to the second terminal, the second end of the second shunt circuit is coupled to a fourth terminal, wherein the fourth terminal is a second reference voltage terminal. A switching device includes: a first circuit, a first terminal of the first circuit is coupled between a first terminal and a second terminal, and a second terminal of the first circuit is coupled to the first terminal. Between the terminal and the second terminal, or coupled to a third terminal, the first circuit includes: a first switch, the first end of the first switch is coupled to the first end of the first circuit, and the first end of the first switch is coupled to the first end of the first circuit. The second end of a switch is coupled to the second end of the first circuit, the first switch is turned on or off according to a first control signal; and a second switch is connected in parallel with the first switch, according to a first control signal. The two control signals are turned on or off, wherein the first switch and the second switch include the same type of transistor, Wherein, in a surge protection mode, the second switch is turned on to discharge a surge current, wherein the first end of the first circuit is coupled to the first terminal, and the second end of the first circuit coupled to the second terminal, wherein the switching device further includes: a third switch, a first end of the third switch is coupled to the first terminal or coupled to the second terminal, and a second end of the third switch is coupled to is connected to the third terminal, and the third switch is turned on or off according to a third control signal, wherein the first terminal and the second terminal are signal transceiver terminals, and the third terminal is a reference voltage terminal. In a normal mode, the conduction states of the third switch and the first switch are different.

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