CN114465221A

CN114465221A - Voltage withstanding circuit, bus driver and power supply

Info

Publication number: CN114465221A
Application number: CN202210058913.3A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shenzhen Xhorse Electronics Co Ltd
Current assignee: Shenzhen Xhorse Electronics Co Ltd
Priority date: 2022-01-19
Filing date: 2022-01-19
Publication date: 2022-05-10

Abstract

The application relates to a voltage withstanding circuit, a bus driver and a power supply. The withstand voltage circuit includes: the anode of the first unidirectional conduction element is used for being connected with an external circuit; one end of the first resistor is connected with the cathode of the first unidirectional conduction element, and the other end of the first resistor is connected with the control end of the first switching tube; the first end of the first switch tube is connected with the cathode of the first unidirectional conducting element; one end of the second resistor is connected with the second end of the first switching tube, and the other end of the second resistor is connected with the output port; and one end of the pressure-resistant driving module is connected with the second end of the first switching tube, and the other end of the pressure-resistant driving module is connected with the output port. By adopting the circuit, the driving capability of the output port of the driving circuit can be ensured, and the voltage withstanding function can be realized.

Description

Voltage withstanding circuit, bus driver and power supply

Technical Field

The present disclosure relates to the field of circuit technologies, and in particular, to a voltage withstanding circuit, a bus driver, and a power supply.

Background

In a driving circuit, not only is it necessary to ensure that the entire circuit has a specific driving level, but also the circuit needs to have a certain withstand voltage capability. The conventional method uses a diode to limit the current, so as to prevent the high voltage generated at the output port of the circuit from influencing the normal operation of the circuit. However, the conventional withstand voltage circuit cannot secure the driving capability of the output port of the driving circuit and realize the withstand voltage function.

Disclosure of Invention

In view of the above, it is necessary to provide a voltage withstanding circuit, a bus driver, and a power supply, which can ensure the driving capability of the output port of the driving circuit and realize a voltage withstanding function.

A voltage withstand circuit comprising:

the anode of the first unidirectional conducting element is used for being connected with an external circuit;

one end of the first resistor is connected with the cathode of the first one-way conduction element, and the other end of the first resistor is connected with the control end of the first switching tube;

the first end of the first switch tube is connected with the cathode of the first one-way conduction element;

one end of the second resistor is connected with the second end of the first switching tube, and the other end of the second resistor is connected with the output port;

and one end of the pressure-resistant driving module is connected with the second end of the first switching tube, and the other end of the pressure-resistant driving module is connected with the output port.

A bus driver comprises the voltage-resistant circuit.

A power supply comprises the voltage-resistant circuit.

According to the voltage-withstanding circuit, the bus driver and the power supply, through the link formed by the first one-way conduction element, the first resistor, the first switch tube, the second resistor and the voltage-withstanding driving module, the driving capability of the voltage-withstanding driving module, namely the driving capability of an output port of the circuit, can be ensured, meanwhile, the influence of positive and negative high voltage generated by the output port on an external circuit is prevented, and the cost is low.

Drawings

FIG. 1 is a circuit diagram of a withstand voltage circuit in one embodiment;

fig. 2 is a circuit diagram of the voltage-resistant driving module 110 in one embodiment;

fig. 3 is a circuit diagram of a withstand voltage circuit in another embodiment.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present disclosure.

It should be noted that all directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiments of the present application are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly, and the connection may be a direct connection or an indirect connection.

In addition, descriptions in this application as to "first", "second", etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.

It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.

The switch tube in the embodiment of the present application may be a wide bandgap Field Effect Transistor, an IGBT (Insulated Gate Bipolar Transistor), or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The wide bandgap FET may be an SiC FET or a GaN FET. The control end of the switching tube in the embodiment of the present application refers to a gate of the switching tube, the first end is one of a source and a drain, and the second end is different from the first end. Specifically, the first terminal may be a source, and the second terminal may be a drain. A unidirectional conductive element refers to an element having a unidirectional conductive function in one path. The unidirectional conducting element may specifically be a diode. It is understood that the unidirectional conducting element may also be a switching tube in the form of a diode connected into the circuit. The switch tube can realize the function of one-way conduction.

In one embodiment, as shown in fig. 1, a circuit diagram of a voltage withstand circuit in one embodiment is shown. The circuit comprises a first one-way conducting element D1, a first resistor R1, a first switch tube M1, a second resistor R2, an output port PAD, a voltage-withstanding driving module 110 and an external circuit 120. The anode of the first one-way conduction element D1 is used for connection with an external circuit. One end of the first resistor R1 is connected to the cathode of the first unidirectional conducting element D1, and the other end is connected to the control end of the first switch tube M1. A first end of the first switch tube M1 is connected to the cathode of the first one-way conductive element D1. One end of the second resistor R2 is connected to the second end of the first switch M1, and the other end is connected to the output port PAD. One end of the voltage-resistant driving module 110 is connected to the second end of the first switching tube M1, and the other end of the voltage-resistant driving module 110 is connected to the output port PAD.

The voltage-withstanding driving module 110 includes a driving end, and the driving end provides a driving voltage for the voltage-withstanding driving module 110, so as to ensure normal output of the output port PAD. The voltage-withstanding driving module 110 includes a second switching tube and a third switching tube connected to each other to prevent high voltage input.

Specifically, in a normal operation state, a current generated by an external circuit flows through the first unidirectional conducting element D1 and the first resistor R1, and a voltage drop generated across the first resistor R1 makes the second switch tube in the voltage-resistant driving module 110 conduct. When the voltage-withstanding driving module 110 is in operation, a low level is output to the output port PAD, and the voltage drop of the second switching tube is small.

When the output port PAD has a positive high voltage input, since the voltage-resistant driving module 110 has a voltage-resistant function, current cannot flow through the voltage-resistant driving module 110, and current flows from the second resistor R2 through the first switching tube M1. Due to the current limiting function of the first unidirectional conductive element D1, current cannot enter an external circuit, and current flows through the first resistor R1. The first resistor R1 may be grounded so that the high voltage generated at the output port PAD does not flow into the external circuit.

When the output port PAD has negative high voltage input, current cannot flow through the voltage-resistant driving module 110, and the link can resist negative voltage. At this time, the first switching tube M1 is not turned on, and the negative high voltage cannot flow into the external circuit, so that the switch can withstand the negative high voltage.

According to the voltage-resistant circuit, the driving capability of the voltage-resistant driving module, namely the driving capability of the output port of the circuit, can be guaranteed through the link formed by the first one-way conduction element, the first resistor, the first switch tube, the second resistor and the voltage-resistant driving module, and meanwhile, the influence of positive and negative high voltage generated by the output port on an external circuit is prevented, and the cost is low.

In one embodiment, the voltage-resistant driving module 110 includes a second switching tube M2 and a third switching tube M3; the control end of the second switch tube M2 is connected with the second end of the first switch tube M1, and the first end of the second switch tube M2 is connected with the output port; the second end of the third switching tube M3 is connected to the second end of the second switching tube M2, and the control end of the third switching tube M3 is a driving end.

Specifically, as shown in fig. 2, a circuit diagram of the voltage-resistant driving module 110 in one embodiment is shown. The second switching tube M2 may be of the same type as the third switching tube M3, including the second switching tube M2. If the third switch M3 is an NMOS transistor, the second switch M2 is also an NMOS transistor.

In this embodiment, the third switching tube M3 is used as a driving tube to generate a driving level, and the second switching tube M2 is provided to achieve the effect of enabling the circuit to have positive and negative high voltage resistance without reducing the driving level.

In one embodiment, the first switch transistor M1 is a PMOS transistor; the second switch tube M2 is an NMOS tube; the third switch transistor M3 is an NMOS transistor.

Specifically, the PMOS transistor is turned on when Vgs is smaller than a certain value, and the NMOS transistor is turned on when Vgs is larger than a certain value. In a normal state, since the third switch transistor M3 is an NMOS transistor, the control terminal of the third switch transistor M3 is an N-type driving terminal, and then the VDRN is a high input, so that the third switch transistor M3 is turned on. Since the second switch transistor M2 is an NMOS transistor, a suitable voltage drop is generated by the first resistor R1, so that the first switch transistor M1 (PMOS transistor) operates in a linear region. That is, the voltage between the first resistor R1 and the first switch tube M1 is low level, and the voltage between the first switch tube M1 and the second switch tube M2, that is, the gate voltage of the second switch tube M2, is equal to the voltage between the first unidirectional conductive element D1 and the first switch tube M1, and is equal to VDD inputted by the external circuit 120 minus the threshold of the first unidirectional conductive element D1. Therefore, the second switch M2 can be turned on, and the Vds drop generated by the second switch M2 is very low, which ensures that the voltage at the output port can be very low during normal driving.

In this embodiment, the third switch M3 is an NMOS transistor, so the driving terminal is an N-type driving terminal; through the cooperation of the PMOS tube and the NMOS tube, the output level of the output port is lower, and the circuit cost is low.

In one embodiment, the first switch tube M1 includes a first parasitic diode, an anode of the first parasitic diode is connected to the control terminal of the second switch tube M2, and a cathode of the first parasitic diode is connected to the cathode of the first unidirectional conducting element D1;

the second switching tube M2 includes a second parasitic diode, an anode of the second parasitic diode is connected to the output port, and a cathode of the second parasitic diode is connected to the second end of the third switching tube M3;

the third switching tube M3 includes a third parasitic diode, an anode of the third parasitic diode is connected to the first end of the third switching tube M3, and a cathode of the third parasitic diode is connected to the second end of the second switching tube M2.

In the case that the third switching tube M3 has no input driving level, a high voltage may appear at the output port. The other end of the first resistor R1 may be connected to ground, and may also be connected to ground through a third resistor R3.

Specifically, in a normal state, the first switch transistor M1 is turned on, and the gate of the second switch transistor M2 is at a high level, so that the second switch transistor M2 is turned on, and therefore, when the voltage-resistant driving module operates, the first switch transistor M2 outputs a low level to the output port PAD.

In the case of a positive high voltage appearing at the output port, i.e., in the case of no driving level of the third switching tube M3, since the cathode of the second switching tube M2 is connected to the second end of the third switching tube M3, a current can flow to the third switching tube M3 through the second switching tube M2. Since the cathode of the third switching tube M3 is connected to the second end of the second switching tube M2, current cannot flow through the third switching tube M3, and thus the link from the output port to the third switching tube M3 can withstand high voltage. In addition, in the case of a high voltage appearing at the output port, a current may flow through the second resistor R2 and the first switch tube M1. Due to the limitation of the first unidirectional conductive element D1, the current does not enter the external circuit 120 after flowing through the first resistor R1, and therefore the link can withstand high voltage.

In the case where a negative high voltage occurs at the output port, that is, in the case where the third switching transistor M3 has no driving level, since the connection directions of the second parasitic diode and the third parasitic diode are opposite, the voltage-resistant driving module 110 can withstand the negative high voltage.

In this embodiment, the direction of current flowing is controlled by the setting direction of the parasitic diode, so that the driving circuit can resist positive and negative high voltages.

In one embodiment, the voltage-withstanding circuit further includes a fourth switching tube M4; the first end of the fourth switching tube M4 is connected to one end of the first resistor R1, the second end of the fourth switching tube M4 is connected to the control end of the first switching tube M1, and the control end of the fourth switching tube M4 is an enable end.

Specifically, the fourth switching tube M4 is connected between the first unidirectional conducting element D1 and the first switching tube M1, and the control end of the fourth switching tube M4 is an enabling end, and the on-off of the fourth switching tube M4 can be controlled through the enabling end. The second terminal of the fourth switching tube M4 may also be grounded.

Then, in the enabled state, in the case where a positive high voltage is input to the output port, since the voltage-resistant driving module 110 has a function of withstanding a high voltage, the link can withstand a high voltage. At this time, the fourth switching tube M4 and the first switching tube M1 are both turned on, and the first unidirectional conducting element D1 is not turned on, so that the link can withstand high voltage. Because the resistance values of the first resistor R1 and the second resistor R2 are both large, only a small current flows to the ground after a high voltage flows through the two resistors, and the high-voltage circuit can resist a positive high voltage and limit the current magnitude to the ground.

When the first switch tube M1 is turned off in the enable off state, the link formed by the second resistor R2, the first switch tube M1 and the first resistor R1 is in an open circuit state, and therefore, the high-voltage circuit can withstand high voltage without forming a load to the ground. Then, by adding the fourth switching tube M4, the load to ground when a positive high voltage appears at the output port can be reduced.

In one embodiment, the withstand voltage circuit further includes a third resistor R3; one end of the third resistor R3 is connected to the second end of the fourth switching tube M4, and the other end of the third resistor R3 is connected to ground.

In this embodiment, the third resistor R3 is connected, so that the current can be reduced to ground when a positive high voltage or a negative high voltage appears at the output port.

In one embodiment, the voltage-withstanding circuit further includes a second one-way conduction element D2; the anode of the second one-way conductive element D2 is used to connect to the external circuit 120 through the voltage withstanding module, and the cathode of the second one-way conductive element D2 is connected to the output port.

Specifically, in the case where a positive high voltage appears at the output port, a current cannot flow through the second one-way conduction element D2.

The anode of the second one-way conduction element D2 is connected to the external circuit 120 through the voltage-withstanding module, and the cathode of the second one-way conduction element D2 is connected to the output port, so that when a negative high voltage occurs at the output port, the input level of the external circuit 120 cannot pass through the voltage-withstanding module, and thus the link formed by the voltage-withstanding module and the second one-way conduction element D2 can withstand the negative high voltage. The second unidirectional conducting element D2 may also be connected to the output port through a fourth resistor R4.

In this embodiment, by accessing the second unidirectional conducting element D2, when there is more than one interface on the external circuit 120, the resistance to positive and negative high voltages can be achieved at the same time.

In one embodiment, the voltage withstanding module includes a third one-way conductive element D3 and a fourth one-way conductive element D4;

the anode of the third one-way conduction element D3 is connected with the anode of the second one-way element; the cathode of the third one-way conduction element D3 is used for connecting with the external circuit 120;

the anode of the fourth one-way conduction element D4 is connected with the anode of the second one-way element; the cathode of the fourth one-way conductive element D4 is used for connecting with the external circuit 120.

In this embodiment, the second unidirectional conducting element D2, the third unidirectional conducting element D3, and the fourth unidirectional conducting element D4 can resist positive and negative high voltages, and the circuit has low cost.

In one embodiment, as shown in fig. 3, fig. 3 is a circuit diagram of a withstand voltage circuit in another embodiment. The circuit in the dotted box portion of the figure is an external circuit 120. In the figure, the first switch transistor M1 is a PMOS transistor, the second switch transistor M2 is an NMOS transistor, the third switch transistor M3 is an N-type LDMOS (Laterally-diffused metal-oxide semiconductor) driver transistor, and the fourth switch transistor M4 is an N-type LDMOS transistor. The switch transistor M5 is an N-type LDMOS transistor. The switch transistor M6 is a P-type LDMOS transistor. The fourth switching tube M4 is an enable tube. The N-type LDMOS can over-meet the requirements of high voltage resistance and power control. IB is the bias current flowing. VSW is the enable input of the fourth switching tube M4. VDRN is the driving terminal input of the third switch tube M3. When the driving terminal VDRN has a voltage input, the enabling terminal VSW also has a voltage input.

In a normal working state, IB is a bias current input, at the moment, the MOS tube where D3 is located is conducted,

the current flows through the fourth unidirectional conducting element D4, so that the voltage of the link R is higher than the threshold voltage of the switching tube M5, the M5 tube is turned on, the link R is pulled low, the switching tube M6 is turned on, the first unidirectional conducting element D1 is turned on, the current flows through the first resistor R1 and the third resistor R3, wherein the resistance of the R1 is far greater than that of the R3, a suitable voltage drop is generated, so that the first switching tube M1 operates in the linear region, that is, the link R is at a low level, and the voltage of the link R is equal to the voltage of the link R and is equal to the voltage obtained by subtracting the threshold of the first unidirectional conducting element D1 from VDD. Therefore, the second switch tube M2 is turned on and the voltage drop of the generated VDS is very low, so that the voltage of the PAD at the output port can be very low during normal driving.

High positive pressure resistance: when the fourth switch M4 is turned on, the second switch M2 is turned on when the output PAD has a high voltage of 40V. Under the condition that the third switching tube M3 is not driven, the PN junction of the drain electrode of the third switching tube M3 to the substrate is not conducted, so that the link can resist high voltage. The second unidirectional element D2 is also non-conductive and the link is also tolerant to high voltages. At this time, the first switching tube M1 (the drain of which can withstand high voltage) and the fourth switching tube M4 (the drain of which can withstand high voltage) are both turned on. The link (c) and the link (c) are also high voltages (the divided voltages of the first resistor R1 and the second resistor R2 respectively), the first one-way conductive element D1 is not conductive, and the path can resist high voltage. Because the resistance values of the first resistor R1 and the second resistor R2 are both large, only a small current flows to the ground after a high voltage flows through the two resistors, and the high-voltage resistor can resist high voltage and limit the current.

Resisting positive high pressure: when the enable is in an off state, that is, under the condition that the fourth switching tube M4 is not conducted, the output port PAD has a high voltage, the fourth switching tube M4 is not conducted, the second switching tube M2 is conducted, and the voltages are high, the first unidirectional conducting element D1 and the second unidirectional conducting element D2 are not conducted, and the link can resist the high voltage. The second parasitic diode of the second switching tube M2 is turned on, the third parasitic diode of the third switching tube M3 is turned off, and the path is also resistant to high voltage. The second resistor R2 reduces the current to ground and protects the Vgs of the second switch M2 from breakdown.

Resisting negative high pressure: when the output port PAD has a voltage of-40V in the enabled and open state, the PN junction from the substrate to the drain of the second switch tube M2 is not conducted, and the negative voltage can be resisted. The PN junction from the drain of the third switching tube M3 to the substrate terminal is non-conductive and can withstand a negative voltage. At this time, the current of the MOS transistor where the third unidirectional conducting element D3 is located all flows through the second unidirectional conducting element D2, the link is low voltage, and cannot be conducted to the power supply through the PN junction of the MOS transistor where the third unidirectional conducting element D3 is located. And the fourth unidirectional conducting element D4 is not conducted, the fourth resistor R4 can play a role in limiting current and can resist negative voltage.

Resisting negative high pressure: when the output port PAD has a voltage of-40V in the enabling and closing state, the PN junction from the substrate to the drain of the second switch tube M2 is not conducted, and the negative pressure can be resisted. The PN junction from the drain of the third switching tube M3 to the substrate terminal is non-conductive and can withstand a negative voltage. The link is low voltage, the fourth one-way conduction element D4 is not conducted, and negative pressure can be resisted.

The voltage-resistant circuit can be applied to a bus driver and a power supply.

The above description is only a preferred embodiment of the present application, and not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application, or which are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. A voltage withstand circuit, comprising:

and one end of the voltage-resistant driving module is connected with the second end of the first switching tube, and the other end of the voltage-resistant driving module is connected with the output port.

2. The circuit according to claim 1, wherein the voltage-resistant driving module comprises a second switching tube and a third switching tube;

the control end of the second switch tube is connected with the second end of the first switch tube, and the first end of the second switch tube is connected with the output port;

the second end of the third switching tube is connected with the second end of the second switching tube, and the control end of the third switching tube is a driving end.

3. The circuit of claim 2, wherein the first switch transistor is a PMOS transistor; the second switch tube is an NMOS tube; the third switching tube is an NMOS tube.

4. The circuit of claim 2, wherein the first switch tube comprises a first parasitic diode, an anode of the first parasitic diode is connected to the control terminal of the second switch tube, and a cathode of the first parasitic diode is connected to the cathode of the first one-way conduction element;

the second switching tube comprises a second parasitic diode, the anode of the second parasitic diode is connected with the output port, and the cathode of the second parasitic diode is connected with the second end of the third switching tube;

the third switching tube comprises a third parasitic diode, the anode of the third parasitic diode is connected with the first end of the third switching tube, and the cathode of the third parasitic diode is connected with the second end of the second switching tube.

5. The circuit of claim 1, further comprising a fourth switching tube; the first end of the fourth switch tube is connected with one end of the first resistor, the second end of the fourth switch tube is connected with the control end of the first switch tube, and the control end of the fourth switch tube is an enabling end.

6. The circuit of claim 5, further comprising a third resistor; one end of the third resistor is connected with the second end of the fourth switching tube, and the other end of the third resistor is connected with the ground.

7. The circuit of claim 1, further comprising a second unidirectional conducting element;

and the anode of the second one-way conduction element is used for being connected with the external circuit through a voltage-withstanding module, and the cathode of the second one-way conduction element is connected with the output port.

8. The circuit of claim 7, wherein the voltage-tolerant module comprises a third one-way conducting element and a fourth one-way conducting element;

the anode of the third unidirectional conduction element is connected with the anode of the second unidirectional single-pass element; the cathode of the third one-way conduction element is used for being connected with an external circuit;

the anode of the fourth unidirectional conducting element is connected with the anode of the second unidirectional single-pass element; and the cathode of the fourth one-way conduction element is used for being connected with an external circuit.

9. A bus driver comprising the voltage-resistant circuit according to any one of claims 1 to 8.

10. A power supply comprising the voltage-resistant circuit according to any one of claims 1 to 8.