CN111082647B

CN111082647B - Switching circuit and multiplexer using the same

Info

Publication number: CN111082647B
Application number: CN201811223159.4A
Authority: CN
Inventors: 宋亚轩; 陈力辅
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2018-10-19
Filing date: 2018-10-19
Publication date: 2021-03-30
Anticipated expiration: 2038-10-19
Also published as: CN111082647A

Abstract

A switching circuit, comprising: a switching element control circuit for receiving a first voltage and a second voltage; a first type-switching element coupled to the switching element control circuit and receiving a first control voltage; a first-type-two switching element coupled to the switching element control circuit and the first-type-one switching element; and a second-type second switch element coupled to the first-type first switch element and the first-type second switch element. When the second voltage is higher than the first voltage, the switch element control circuit enables the first type two switch element to be conducted, the conduction of the first type two switch element enables the second type two switch element not to be conducted, and when the second voltage is higher than the first voltage and the first voltage is a first preset voltage, the first type one switch element does not conduct.

Description

Switching circuit and multiplexer using the same

Technical Field

The present invention relates to a switching circuit and a multiplexer using the same, and more particularly, to a switching circuit having an anti-leakage mechanism and a high voltage tolerance and a multiplexer using the same.

Background

In recent electronic devices, Type _ C (C Type) connectors are becoming more and more popular. FIG. 1 is a schematic diagram of one example of a prior art Type _ C connector. As shown in FIG. 1, the Type _ C connector 100 includes a VBUS pin, an SBU _1 pin, and an SBU _2 pin. The VBUS pin is a pin for receiving high voltage, and the pin of the Type _ C connector 100 may be connected incorrectly or be wet, which may cause short circuit between the VBUS pin and the SBU _1 pin or the SBU _2 pin. Therefore, the circuit connecting the SBU _1 pin and the SBU _2 pin must have a mechanism of withstanding high voltage. In addition, the circuit connecting the SBU _1 pin and the SBU _2 pin must have a mechanism for preventing leakage, so as to prevent leakage problem that may occur under various conditions.

To support the function of forward and reverse plugging, the Type _ C connector usually has a multiplexer therein to connect the SBU _1 pin, SBU _2 pin and other circuits (e.g., IC inside the mobile phone), however, such multiplexer usually does not consider the aforementioned problems of leakage prevention and high voltage resistance.

Disclosure of Invention

Therefore, an object of the present invention is to provide a switch circuit with an anti-leakage mechanism and a high voltage resistance.

Another objective of the present invention is to provide a multiplexer having an anti-leakage mechanism and an anti-high voltage function.

An embodiment of the present invention discloses a switching circuit, including: a switching element control circuit for receiving a first voltage and a second voltage; a first type-one switching element including a first terminal coupled to the switching element control circuit and a second terminal receiving a first control voltage, wherein the first control voltage is related to the first voltage; a first type-two switch element including a first end coupled to the switch element control circuit and a second end coupled to the first end of the first type-one switch element; and a second-type second switch element including a first terminal coupled to the first terminal of the first-type first switch element and a second terminal coupled to the third terminal of the first-type second switch element. When the second voltage is higher than the first voltage, the switch element control circuit enables the first type two switch element to be conducted, and the conduction of the first type two switch element enables the second type two switch element not to be conducted; when the second voltage is higher than the first voltage and the first voltage is a first predetermined voltage, the first type-one switching element is not conducted.

An embodiment of the present invention discloses a multiplexer, including: a plurality of input terminals; a plurality of output terminals; and the conducting state of the switch circuits determines the electric connection mode between the input end and the output end. At least one of the switching circuits contains all the elements of the aforementioned switching circuit.

According to the embodiment, the switch circuit provided by the invention has a perfect leakage-proof motor mechanism, and a high-voltage resistant element and a resistor with a higher resistance value can be adopted, so that the leakage-proof motor mechanism is more perfect. It should be noted, however, that the present invention is not limited to solving such problems.

Drawings

FIG. 1 is a schematic diagram of one example of a prior art Type _ C connector.

Fig. 2 shows a block diagram of a switching circuit according to an embodiment of the invention.

Fig. 3 shows a circuit diagram of a switching circuit according to an embodiment of the invention.

Fig. 4 shows a circuit diagram of a voltage supply circuit according to an embodiment of the invention.

Fig. 5 shows a circuit diagram of the switching element control circuit of fig. 2 and 3 according to an embodiment of the present invention.

Fig. 6 shows an application example of the switch circuit shown in fig. 2.

Description of the symbols

100 Type _ C connector

200 switching circuit

201 switching element control circuit

600 multiplexer

SW _11 first type-switching element

SW _12 second type-switch element

SW _13 third type-switch element

SW _14 fourth type-switch element

SW _15 fifth type-one switch element

SW _21 first type two-switch element

SW _22 second type two-switch element

SW _23 third type two switch element

SW _24 fourth type two switch element

SW _25 fifth type two switch element

R _ a resistance

P _1 first PMOS

P _2 second PMOS

P_3、P_4 PMOS

R _1, R _2 and R _3 resistors

D _1 and D _2 diodes

SC _1, SC _2, SC _3, SC _4 switching circuits

Detailed Description

The concept of the present invention will be described in terms of various embodiments, but it should be understood that the first and second embodiments are only used for distinguishing independent elements, and are not used for indicating the number, order or position of the elements. For example, the first NMOS (N-channel Metal Oxide Semiconductor) and the second NMOS represent that they are different NMOS, and do not represent that the first NMOS must appear in the earlier description.

Fig. 2 shows a block diagram of a switching circuit according to an embodiment of the invention. The switch circuit 200 includes a switch element control circuit 201, a first-type-one switch element SW _11, a first-type-two switch element SW _21, a second-type-two switch element SW _22, a fourth-type-one switch element SW _14, a fifth-type-one switch element SW _15, a fourth-type-two switch element SW _24, a fifth-type-two switch element SW _25, and a resistor ra.

The switching element control circuit 201 receives a first voltage V _1 and a second voltage V _ 2. The first type-one switching element SW _11 includes a first terminal coupled to the switching element control circuit 201 and a second terminal receiving a first control voltage CV _1, wherein the first control voltage CV _1 is related to the first voltage V _1, for example, is proportional to the first voltage V _ 1. The first-type-two switch element SW _21 includes a first terminal coupled to the switch element control circuit 201 and a second terminal coupled to the first terminal of the first-type-one switch element SW _ 11. The second-type second switch element SW _22 includes a first terminal coupled to the first terminal of the first-type first switch element SW _11 and a second terminal coupled to the third terminal of the first-type second switch element SW _ 21. The fourth type-two switch element SW _24 includes a first terminal coupled to a third terminal of the second type-two switch element SW _22, a third terminal coupled to the first type-one switch element SW _11, and a second terminal coupled to a third voltage V _ 3. The fifth type-two switch element SW _25 includes a first terminal coupled to the third voltage V _3 and a second terminal coupled to the first voltage V _ 1. A first terminal of the resistor ra is coupled to the third terminal of the fourth-type-two switch device SW _24, a third terminal of the fifth-type-two switch device SW _25, and a second terminal of the first voltage V _ 1.

The first voltage V _1 can be a system voltage, for example, the switching circuit 200 can use a voltage operated by the Type _ C connector when the Type _ C connector is used, and the control voltage CV _1 is a voltage related to the first voltage V _ 1. For example, when the first voltage V _1 is zero, the control voltage CV _1 is also zero. The second voltage V _2 can be the voltage of the SBU pin (which can be the aforementioned SBU + pin or SBU-pin). The third voltage V _3 may be a voltage provided by a circuit or a device to which the switch circuit 201 is connected. The following embodiments will be described based on the example, but the first voltage V _1, the second voltage V _2 and the third voltage V _3 are not limited to the foregoing examples, and the definition thereof may be different according to the electronic device or the circuit used by the switch circuit.

The operation of the switching circuit 201 of fig. 2 will be described in different embodiments. It should be noted that the values of the first voltage V _1, the second voltage V _2 and the third voltage V _3 in the embodiments are only for illustration and are not limited to the values in the embodiments, and any values corresponding to the relationship among the first voltage V _1, the second voltage V _2 and the third voltage V _3 in the embodiments are all within the scope of the present invention. For example, in an embodiment, the first voltage V _1 is 0V, and the second voltage V _2 is 3.3.V, all the cases where the second voltage V _2 is higher than the first voltage V _1 are applicable to this embodiment.

In some cases, the first voltage V _1 is 0V, the second voltage V _2 is a predetermined voltage (e.g., 3.3V or 20V) higher than the first voltage V _1, and the third voltage V _3 is 0V. For example, the switch circuit 200 is used in the Type _ C connector, but the Type _ C connector is just powered on, is not operated at the system voltage, and does not receive voltage from other circuits or devices. In this case, the switch device control circuit 201 receives the second voltage V _2 to turn on the first-type second switch device SW _21, and the turning on of the first-type second switch device SW _21 turns off the second-type second switch device SW _22, so as to prevent the second voltage V _2 from leaking from the second-type second switch device SW _ 22. And the first voltage V _1 is 0V, the first control voltage CV _1 is also 0 or a lower voltage because it is associated with the first voltage V _1, which turns off the first type-one switch element SW _ 11. Please note that the first voltage V _1 can be replaced by a first predetermined voltage (e.g., 3.3V) which is not 0 but does not turn on the first type-one switching element SW _ 11. Thus, leakage of current from the first type-one switching element SW _11 due to the second voltage V _2 can be prevented.

In some cases, the first voltage V _1 is 0V, the second voltage V _2 is 0V, and the third voltage V _3 is 3.3V. For example, the switch circuit 200 is used in a Type _ C connector, but the Type _ C connector can receive the power of the connected circuit or device, but its SUB pin cannot receive a voltage. In this case, the third voltage V _3 makes the fourth-type second switch element SW _24 non-conductive through the fifth-type second switch element SW _ 25. This prevents the third voltage V _3 from leaking from the fourth type-two switching element SW _ 24.

In one embodiment, the first voltage V _1 is 3.3V, the second voltage V _2 is 0V, and the third voltage V _3 is 3.3V. For example, when the switch circuit 200 is used in a Type _ C connector, the Type _ C connector can receive the power of the connected circuit or device and the power of the system, but the SUB pin thereof cannot receive the voltage. In this case, the first voltage V _1 makes the second type switching element SW _24 non-conductive through the resistor R _ a. This prevents the third voltage V _3 from leaking from the fourth type-two switching element SW _ 24.

In one embodiment, the switch circuit 100 further includes a fourth-type first switch element SW _14, which includes a first terminal coupled to the third terminal of the first-type second switch element SW _21, a second terminal coupled to a second predetermined voltage (e.g., ground), and a third terminal coupled to a second control voltage CV _ 2. In this embodiment, the switch circuit 100 may further include a fifth-type switching element SW _15, which includes a first terminal coupled to the third terminal of the fourth-type switching element SW _24, a second terminal coupled to a second predetermined voltage (e.g., ground), and a third terminal coupled to a second control voltage CV _ 2. The switching element control circuit 201 also receives the second control voltage CV _2, and the switching element control circuit 201 is turned off when the second control voltage CV _2 turns on the fourth type-one switching element SW _14 and the fifth type-one switching element SW _ 15. On the contrary, when the second control voltage CV _2 makes the fourth type-one switching element SW _14 and the fifth type-one switching element SW _15 turned off, the switching element control circuit 201 operates normally.

In one embodiment, when the switch circuit 200 is not operating normally, i.e., the signal cannot be directly transmitted from the SBU pin providing the second voltage V _2 to the IC providing the third voltage V _3, the second control voltage CV _2 makes the switch device control circuit 201 operate but makes the fourth type-one switch device SW _14 and the fifth type-one switch device SW _15 not conductive. In this case, the aforementioned anti-creeping operation is performed. On the contrary, when the switch circuit 200 can operate normally, i.e. the signal can be directly transmitted from the SBU pin providing the second voltage V _2 to the IC providing the third voltage V _3, the second control voltage CV _2 turns off the switch device control circuit 201 but turns on the fourth type-one switch device SW _14 and the fifth type-one switch device SW _ 15.

It should be noted that the switch circuit provided in the present invention is not limited to include the components described in fig. 2. In response to different anti-leakage requirements, the switch circuit may only include some of the components described in fig. 2.

An example of the detailed structure of each component shown in fig. 2 will be described below, however, it should be noted that each component shown in fig. 2 is not limited to the following embodiments, and any structure that can achieve the same function should be included in the scope of the present invention.

Fig. 3 shows a circuit diagram of a switching circuit according to an embodiment of the invention. As shown in fig. 3, the first-type second switch element SW _21 is a PMOS (P-channel Metal Oxide Semiconductor), and a gate, a source and a drain of the first-type second switch element SW _21 are respectively a first terminal, a second terminal and a third terminal of the first-type second switch element SW _ 21. The second-type second switching element SW _22 is also a PMOS, and its source and gate serve as the first terminal and the second terminal of the aforementioned second-type second switching element SW _22, respectively. The first-type switching element SW _11 is an NMOS, and the drain and the gate of the first-type switching element SW _11 serve as the first terminal and the second terminal of the first-type switching element SW _11, respectively.

In the case where the first voltage V _1 is 0V, the second voltage V _2 is a predetermined voltage (e.g., 3.3V or 20V) higher than the first voltage V _1, and the third voltage V _3 is 0V, the switch device control circuit 201 pulls down the gate voltage of the first-type second switch device SW _21 to turn on, so that the VGS of the second-type second switch device SW _22 is 0 and thus is not turned on. In the case where the first control voltage CV _1 is small (0 or a low voltage slightly greater than 0), the first-type switching element SW _11 is not turned on. As described above, the first voltage V _1 may be replaced with a first predetermined voltage (e.g., 3.3V) that is not 0 but does not turn on the first type-one switching element SW _ 11.

When the first voltage V _1 is 0V, the second voltage V _2 is 0V, and the third voltage V _3 is 3.3V. The third voltage V _3 pulls up the gate voltage of the fourth-type-two switching element SW _24 through the fifth-type-two switching element SW _ 25. Therefore, the gate-drain voltage VGD of the fourth-type second switching element SW _24 is 0, so that it is not turned on. In the case where the first control voltage CV _1 is small (0 or a low voltage slightly greater than 0), the first-type switching element SW _11 is not turned on.

When the first voltage V _1 is 3.3V, the second voltage V _2 is 0V, and the third voltage V _3 is 3.3V, the first voltage V _1 pulls the gate voltage of the fourth-type second switching element SW _24 high through the resistor R _1, so that the first voltage V _1 is turned off. The third voltage V _3 does not leak through the fourth type-two switching element SW _ 24. The first control voltage CV _1 is not enough to turn on the first type-one switching element SW _11 because it corresponds to the first voltage V _1, and the first voltage V _1 does not leak through the first type-one switching element SW _ 11.

In order to prevent the second voltage V _2 from leaking through the body of the second-type second switch device SW _22, the switch circuit 200 may include a voltage providing circuit for providing a leakage preventing voltage V _ LP to the body of the second-type second switch device SW _ 22. As shown in fig. 4, the voltage providing circuit 400 includes two PMOS P _3 and P _4 connected in series, which are respectively coupled to the second voltage V _2 and the third voltage V _3 for providing V _ LP. However, this voltage supply circuit is not limited to the example illustrated in fig. 4.

Fig. 5 shows a circuit diagram of the switching element control circuit 201 of fig. 2 and 3 according to an embodiment of the present invention. As shown in fig. 5, the switching element control circuit 201 includes a first PMOS P _1, a second PMOS P _2, a resistor string (in this case, resistors R _1 and R _2), a second-type-one switching element SW _12, a third-type-one switching element SW _13, and a third-type-two switching element SW _ 23.

The first PMOS P _1 includes a source coupled to the second voltage V _2, and a drain and a gate thereof are shorted. The source of the second PMOS P _2 is coupled to the drain of the first PMOS P _1, the drain is short-circuited with the gate, and the drain is coupled to the resistor string and the gate of the second-type switching element SW _ 21. The first PMOS P _1 and the second PMOS P _2 can be used as a voltage adjusting circuit, and the source-gate voltage VSG of the first PMOS P _1 and the second PMOS P _2 is used for reducing the second voltage V _2 to generate an adjusting voltage, so that the technical effect of preventing the electric leakage can be provided. However, any circuit that provides the voltage reduction effect of the first PMOS P _1 and the second PMOS P _2 is within the scope of the present invention. When the second voltage V _2 is greater than a predetermined value and the switching element control circuit 201 operates normally (e.g., the aforementioned 3.3V), the adjustment voltage can turn on the second-type-one switching element SW _12 through the resistor R _1 and the third-type-two switching element SW _ 23.

The first terminal of the second type-one switching element SW _12 is coupled to the resistor string and the second terminal is coupled to a second predetermined voltage (e.g., a ground potential). The third-type second switch element SW _23 includes a first terminal coupled between the resistors (e.g., between the resistor R _1 and the resistor R _2) of the resistor string, a second terminal coupled to the second-type first switch element SW _12, and a third terminal receiving the second control voltage CS _ 2. The third-type switch element SW _13 includes a first terminal coupled to the second-type switch element SW _12, a second terminal coupled to the third terminal of the third-type switch element SW _23, and a third terminal coupled to a second predetermined voltage (e.g., a ground potential).

In one embodiment, the second-type-one switching element SW _12 is an NMOS, and the source, the drain and the gate thereof are respectively the first terminal, the second terminal and the third terminal of the second-type-one switching element SW _ 12. In this embodiment, the third-type-two switching element SW _23 is a PMOS, and the drain, the source and the gate thereof are respectively the first terminal, the second terminal and the third terminal of the third-type-two switching element SW _ 23. The third-type switching element SW _13 is an NMOS, and the drain, the gate and the source thereof are respectively the first terminal, the second terminal and the third terminal of the third-type switching element SW _ 13.

In the embodiment of fig. 5, when the first voltage V _1 is 0V, the second voltage V _2 is a predetermined voltage (e.g., 3.3V or 20V) higher than the first voltage V _1, and the third voltage V _3 is 0V, the second voltage V _2 generates the regulated voltage at the source of the second PMOS P _2 because the drain-gate voltages VGS of the first PMOS P _1 and the second PMOS P _2 are lowered. The regulated voltage can turn on the second-type-one switching element SW _12 through the resistor R _1 and the third-type-two switching element SW _ 23. The turning on of the second-type-one switch element SW _12 pulls down the gate voltage of the first-type-two switch element SW _21 to turn on, thereby turning off the second-type-two switch element SW _22 in fig. 3 as described above. In the embodiment of fig. 5, the switching device control circuit 201 may further include at least one diode D _1, D _2, which may limit the direction of the current flow or a resistor R _3 for controlling the current, but is not limited thereto.

The switch element or the PMOS can use a high-voltage resistant element, so that the switch element circuit has the characteristic of high-voltage resistance, and the resistor can adopt a resistor with higher resistance value, so that the anti-creeping function is more perfect. Further, the foregoing embodiments are not limited to inclusion of all elements shown in the figures. Those skilled in the art will appreciate that only a portion of the circuitry may be operated independently in light of the foregoing disclosure and the desired functionality. Such variations and modifications are intended to be within the scope of the present invention.

Fig. 6 shows an application example of the switch circuit shown in fig. 2. In this embodiment, the switch circuit is applied to a multiplexer. As shown in fig. 6, the multiplexer 600 includes a plurality of switch circuits SC _1-SC _4, wherein the SBU _1 terminal and the SBU _2 terminal represent SBU pins for providing the second voltage V _2, and the AUX + terminal and the AUX-terminal represent connection terminals of another circuit or device for providing the third voltage V _ 3. Each of the switch circuits SC _1-SC _4 may comprise at least a portion of the switch circuit embodiments described above. The first voltage V _1 is a system voltage operated by the multiplexer 600.

However, the switching circuit of the present invention is not limited to the multiplexer having the structure shown in fig. 6, and can be applied to various multiplexers having a plurality of input terminals and a plurality of output terminals. In other words, the multiplexer using the switching circuit of the present invention includes a plurality of switching circuits, a plurality of input terminals and a plurality of output terminals, and the conducting state of the switching circuit determines the electrical connection manner between the input terminals and the output terminals.

According to the above, the multiplexer 600 can determine the connection modes of the AUX + terminal, the AUX-terminal, the SBU _1 terminal and the SBU _2 terminal according to the conduction or non-conduction of the switch circuits SC _1-SC _4, so that the function of positive and negative insertion of the Type C connector can be realized. In any case, the switch circuit provided by the invention can have the function of preventing the electric leakage through the anti-electric leakage mechanism.

The above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made by the claims of the present invention should be covered by the scope of the present invention.

Claims

1. A switching circuit, comprising:

a switching element control circuit for receiving a first voltage and a second voltage;

a first type-one switching element including a first terminal coupled to the switching element control circuit and a second terminal receiving a first control voltage, wherein the first control voltage is related to the first voltage;

a first type-two switch element including a first end coupled to the switch element control circuit and a second end coupled to the first end of the first type-one switch element; and

a second-type second switch element including a first terminal coupled to the first terminal of the first-type first switch element and a second terminal coupled to the third terminal of the first-type second switch element;

when the second voltage is higher than the first voltage, the switch element control circuit enables the first type two switch element to be conducted, and the conduction of the first type two switch element enables the second type two switch element not to be conducted;

when the second voltage is higher than the first voltage and the first voltage is a first predetermined voltage, the first type-one switching element is not conducted.

2. The switch circuit of claim 1, wherein the first-type-two switch element is a PMOS, and a gate, a source and a drain of the first-type-two switch element respectively serve as the first terminal, the second terminal and the third terminal of the first-type-two switch element.

3. The switching circuit according to claim 2, wherein the second-type second switching element is a PMOS, and a source and a gate of the second-type second switching element respectively serve as the first terminal and the second terminal of the second-type second switching element.

4. The switching circuit of claim 1, wherein the switching element control circuit comprises:

a second type-switch element including a first terminal coupled to a second predetermined voltage;

a voltage adjusting circuit for reducing the second voltage to generate an adjusted voltage; and

a resistor string connected in series between a second terminal of the second-type-one switching element and the voltage adjusting circuit.

5. The switching circuit of claim 4 wherein the voltage regulation circuit comprises:

a first PMOS including a source coupled to the second voltage, and a drain and a gate of the first PMOS being shorted;

the source electrode of the second PMOS is coupled with the drain electrode of the first PMOS, the drain electrode of the second PMOS is short-circuited with the grid electrode, and the drain electrode of the second PMOS is coupled with the resistor string;

wherein the second-type-one switching element is an NMOS, and a source and a drain of the second-type-one switching element are respectively used as the first terminal and the second terminal of the second-type-one switching element.

6. The switching circuit of claim 4, wherein the resistor string comprises a plurality of resistors, the switching circuit further comprising:

a second-type switching element including a first terminal coupled between the resistors of the resistor string, a second terminal coupled to the third terminal of the second-type switching element, and a third terminal receiving a second control voltage; and

a third type-one switch element including a first terminal coupled to the third terminal of the second type-one switch element, a second terminal coupled to the third terminal of the third type-two switch element, and a third terminal coupled to the second predetermined voltage.

7. The switching circuit according to claim 6, wherein,

wherein the third-type second switching element is a PMOS, and a drain, a source and a gate of the third-type second switching element are respectively used as the first terminal, the second terminal and the third terminal of the third-type second switching element;

wherein the third-type-one switching element is an NMOS, and a drain, a gate and a source of the third-type-one switching element are respectively used as the first terminal, the second terminal and the third terminal of the third-type-one switching element.

8. The switching circuit of claim 1, further comprising:

a fourth type-one switch element including a first terminal coupled to the third terminal of the first type-two switch element, a second terminal coupled to a second predetermined voltage, and a third terminal coupled to a second control voltage;

the switching element control circuit also receives the second control voltage, and is turned off when the second control voltage turns on the fourth type-one switching element.

9. The switching circuit of claim 1, further comprising:

a fourth type-two switch element including a first end coupled to a third end of the second type-two switch element, a third end coupled to the first type-one switch element, and a second end of a third voltage;

a fifth type-two switch element including a first end coupled to the third voltage and a second end coupled to the first voltage;

when the third voltage is greater than or equal to the first voltage, the third voltage makes the fourth type two switch element non-conductive through the fifth type two switch element.

10. The switching circuit of claim 9, further comprising:

a resistor including a first terminal coupled to a third terminal of the fourth type-two switch device, a first terminal coupled to a third terminal of the fifth type-two switch device, and a second terminal coupled to the first voltage;

when the first voltage and the third voltage are greater than the second voltage, the first voltage makes the fourth type two switch element not conduct through the resistor.