CAN transceiver circuit

Abstract

The application discloses a CAN transceiver. The CAN transceiver comprises a high-side switch, a low-side switch, a first current detection circuit and a second current detection circuit, wherein the current flowing through the high-side switch is a high-side current, the current flowing through the low-side switch is a low-side current, the first current detection circuit generates a high-side detection current according to the high-side current, and the second current detection circuit generates a low-side detection current according to the low-side current. When the high-side bus port or the low-side bus port is short-circuited to a voltage source, the high-side detection current is less than the low-side detection current minus a high-side threshold value; when the high-side bus port or the low-side bus port is short-circuited to a reference ground, the high-side detection current is greater than the low-side detection current plus a low-side threshold value. The application can determine whether the CAN bus is short-circuited to the voltage source or the reference ground according to the high-side detection current and the low-side detection current, and thus precise detection of the short-circuit condition of the CAN bus is realized.

Description

Technical Field

[0001] This invention relates to the field of short-circuit detection technology for CAN bus, and more particularly to a CAN transceiver circuit. Background Technology

[0002] CAN bus (Controller Area Network bus) is a serial communication protocol bus used in real-time applications, widely used in industrial automation, automotive electronics, and other fields. CAN bus is a highly reliable and real-time communication method capable of data transmission between multiple nodes. The CAN bus network mainly consists of two differential signal lines, CAN_High and CAN_Low, which form a twisted pair structure, providing effective immunity to electromagnetic interference. The potential difference on the CAN bus is divided into dominant and recessive levels. The dominant level is logic 0, and the recessive level is logic 1.

[0003] In the prior art, a short circuit in the CAN bus will affect signal transmission. Therefore, it is usually necessary to detect the short circuit in the bus during signal transmission. However, the prior art can only detect the occurrence of a short circuit in the CAN bus but cannot determine the location of the short circuit. Summary of the Invention

[0004] The purpose of this invention is to provide a CAN transceiver circuit to solve the problem in the prior art that the location of the short circuit cannot be determined when a short circuit occurs on the CAN bus.

[0005] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a CAN transceiver circuit, comprising: a high-side bus port for outputting a high-side signal; a low-side bus port for outputting a low-side signal; a high-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a power supply, the second terminal is coupled to the high-side bus port, and the control terminal receives a high-side control signal and turns on and off under the control of the high-side control signal, wherein the current flowing through the high-side switch is a high-side current; and a low-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the low-side bus port, and the second terminal is coupled to a reference... Ground, the control terminal receives the low-side control signal and turns on and off under the control of the low-side control signal, wherein the current flowing through the low-side switch is the low-side current; the first current detection circuit is coupled to the high-side switch and generates a high-side detection current based on the high-side current, wherein the high-side detection current is proportional to the high-side current; the second current detection circuit is coupled to the low-side switch and generates a low-side detection current based on the low-side current, wherein the low-side detection current is proportional to the low-side current; wherein when the high-side bus port or the low-side bus port is shorted to a voltage source, the high-side detection current is less than the low-side detection current minus the high-side threshold.

[0006] To achieve one of the above-mentioned objectives, the present invention also provides a CAN transceiver circuit, comprising: a high-side bus port for outputting a high-side signal; a low-side bus port for outputting a low-side signal; a high-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a power supply, the second terminal is coupled to the high-side bus port, and the control terminal receives a high-side control signal and turns the switch on and off under the control of the high-side control signal, wherein the current flowing through the high-side switch is a high-side current; and a low-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the low-side bus port, and the second terminal is coupled to a reference ground. The control terminal receives a low-side control signal and turns the switch on and off under its control. The current flowing through the low-side switch is the low-side current. A first current detection circuit is coupled to the high-side switch and generates a high-side detection current based on the high-side current, wherein the high-side detection current and the high-side current are proportional. A second current detection circuit is coupled to the low-side switch and generates a low-side detection current based on the low-side current, wherein the low-side detection current and the low-side current are proportional. When either the high-side bus port or the low-side bus port is shorted to the reference ground, the high-side detection current is greater than the low-side detection current plus the low-side threshold.

[0007] To achieve one of the above-mentioned objectives, the present invention also provides a CAN transceiver circuit, comprising: a high-side bus port for outputting a high-side signal; a low-side bus port for outputting a low-side signal; a high-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a power supply, and the control terminal receives a high-side control signal, wherein the current flowing through the high-side switch is a high-side current; a high-side withstand voltage circuit having a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of the high-side switch; the second terminal is coupled to the high-side bus port; a low-side withstand voltage circuit having a first terminal and a second terminal, wherein the first terminal is coupled to the low-side bus port; and a low-side switch having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of the low-side withstand voltage circuit, and the second terminal is coupled to the high-side bus port; a low-side withstand voltage circuit having a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of the low-side withstand voltage circuit, and the second terminal is coupled to the low-side bus port; a high-side withstand voltage circuit having a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of the low-side withstand voltage circuit, and the second terminal is coupled to the low-side bus port; a low-side switch having a first terminal and a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of the low-side withstand voltage circuit, and the second terminal is coupled to the low-side bus port; a high-side withstand voltage circuit having a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of the low-side withstand voltage circuit, and the second terminal is coupled to the low-side bus port; a low ... Connected to a reference ground, the control terminal receives a low-side control signal, wherein the current flowing through the low-side switch is the low-side current; a first current detection circuit, coupled to the high-side switch, generates a high-side detection current based on the high-side current, wherein the high-side detection current and the high-side current are proportional; a second current detection circuit, coupled to the low-side switch, generates a low-side detection current based on the low-side current, wherein the low-side detection current and the low-side current are proportional; and a parasitic current mirror circuit, coupled to the high-side switch and the low-side switch, generates an adjustment current, wherein the magnitude of the adjustment current is related to the difference between the high-side current and the low-side current; wherein when the high-side bus port or the low-side bus port is shorted to a voltage source, the high-side detection current is less than the low-side detection current minus the first comparison value.

[0008] Compared with the prior art, the present invention has the following beneficial effects: the present invention can determine that the bus is short-circuited to the voltage source when the high-side detection current is less than the low-side detection current minus the high-side threshold; and determine that the bus is short-circuited to the reference ground when the high-side detection current is greater than the low-side detection current plus the low-side threshold. In this way, the short-circuit situation of the CAN bus can be determined, so that the repair of the CAN bus can be accurately located. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the connection structure of the CAN transceiver circuit 100 in one embodiment of the present invention.

[0010] Figure 2A A schematic diagram of the circuit structure of a CAN transceiver circuit 200 according to an embodiment of the present invention is provided.

[0011] Figure 2B A schematic diagram of the circuit structure of a CAN transceiver circuit 201 according to an embodiment of the present invention is provided.

[0012] Figure 3 A schematic diagram of the circuit structure of a CAN transceiver circuit 300 according to an embodiment of the present invention is provided.

[0013] Figure 4 A schematic diagram of the circuit structure of a CAN transceiver circuit 400 according to an embodiment of the present invention is provided.

[0014] Figure 5 A schematic diagram of the circuit structure of an AN transceiver circuit 500 according to another embodiment of the present invention is provided. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0016] It should be noted that the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," "third," "fourth," "fifth," "sixth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] The phrases "an embodiment," "an embodiment," "an example," and "an example" appearing in various places throughout this specification do not necessarily refer to the same embodiment or example. Those skilled in the art should understand that the specific features, structures, parameters, steps, etc., disclosed in one or more embodiments of this disclosure can be combined in any suitable manner.

[0018] Figure 1 A schematic diagram of a CAN transceiver circuit 100 according to an embodiment of the present invention is provided. The CAN transceiver circuit 100 includes a high-side bus port CANH, a low-side bus port CANL, a high-side switch K1, a low-side switch K2, a first current detection circuit 1, and a second current detection circuit 2. The high-side bus port CANH is used to output a high-side signal VH, and the low-side bus port CANL is used to output a low-side signal VL. The high-side switch K1 has a first terminal, a second terminal, and a control terminal. The first terminal of the high-side switch K1 is coupled to the power supply voltage source VCC, and the second terminal is coupled to the high-side bus port CANH. The control terminal receives a high-side control signal G1 and turns the switch on and off under the control of the high-side control signal G1. The low-side switch K2 has a first terminal, a second terminal, and a control terminal. The first terminal of the low-side switch K2 is coupled to the low-side bus port CANL, and the second terminal is coupled to the reference ground GND. The control terminal receives a low-side control signal G2 and turns the switch on and off under the control of the low-side control signal G2. The current flowing through the high-side switch K1 is called the high-side current I1, and the current flowing through the low-side switch K2 is called the low-side current I2. A first current detection circuit 1 is coupled to the high-side switch K1 and generates a high-side detection current IS1 based on the high-side current I1. The high-side detection current IS1 is proportional to the high-side current I1. In one embodiment, IS1 = K * I1, where K is the mirror image coefficient. A second current detection circuit 2 is coupled to the low-side switch K2 and generates a low-side detection current IS2 based on the low-side current I2. The low-side detection current IS2 is proportional to the low-side current I2. In one embodiment, IS2 = K * I2, where K is the mirror image coefficient.

[0019] exist Figure 1 In the CAN transceiver, when the high-side bus port CANH or the low-side bus port CANL is shorted to the voltage source VCC, the high-side detection current IS1 is less than the low-side detection current IS2 minus the high-side threshold TH1. When the high-side bus port CANH or the low-side bus port CANL is shorted to the reference ground GND, the high-side detection current IS1 is greater than the low-side detection current IS2 plus the low-side threshold TH2. Thus, the CAN transceiver 100 indicates whether the high-side bus port CANH (or the low-side bus port CANL) is shorted to the voltage source VCC or shorted to the reference ground GND based on the magnitudes of the high-side detection current IS1 and the low-side detection current IS2.

[0020] The high-side threshold TH1 and low-side threshold TH2 are bias values ​​set to prevent false short-circuit detections caused by design errors or manufacturing process errors in the high-side detection current IS1 and low-side detection current IS2. In one embodiment, the high-side threshold TH1 is equal to the low-side threshold TH2. In another embodiment, the low-side threshold TH2 is between 0.1mA and 1mA.

[0021] Figure 1 The load resistor R coupled to the high-side bus port CANH and the low-side bus port CANL is also given. When there is a dominant voltage between the high-side bus port CANH and the low-side bus port CANL, a path is formed between the high-side switch K1, the high-side bus port CANH, the load resistor R, the low-side bus port CANL, and the low-side switch K2. The high-side current I1 is equal to the low-side current I2.

[0022] In one embodiment, the high-side switch K1 is a P-type MOSFET. In another embodiment, the low-side switch K2 is an N-type MOSFET. In one embodiment, the voltage value of the voltage source VCC is between 5V and 60V.

[0023] Figure 2A A schematic diagram of a CAN transceiver circuit 200 according to an embodiment of the present invention is provided. The CAN transceiver circuit 200 includes a high-side bus port CANH, a low-side bus port CANL, a high-side switch K1, a low-side switch K2, a first current detection circuit 1, and a second current detection circuit 2. The first current detection circuit 1 includes a first transistor M1. The second current detection circuit 2 includes a second transistor M2. The source terminal of the first transistor M1 is coupled to a voltage source VCC, the gate terminal of the first transistor M1 is coupled to the control terminal of the high-side switch K1, and the drain terminal of the first transistor M1 outputs a high-side detection current IS1. The source terminal of the second transistor M2 is coupled to a reference ground GND, the gate terminal of the second transistor M2 is coupled to the control terminal of the low-side switch K2, and the drain terminal of the second transistor M2 outputs a low-side detection current IS2.

[0024] In one embodiment, the first transistor M1 is a P-type MOS transistor, and the second transistor M2 is an N-type MOS transistor.

[0025] exist Figure 2A In the circuit, the drain of the second transistor M2 is coupled to the drain of the first transistor M1, forming a high-voltage short-circuit detection node W1. The high-voltage short-circuit detection node W1 of the CAN transceiver circuit generates a high-voltage short-circuit indication signal S2H based on the high-side detection current IS1 and the low-side detection current IS2.

[0026] When the high-side detection current IS1 is less than the low-side detection current IS2 minus the high-side threshold TH1, the high-voltage short-circuit indication signal S2H is in its first state. When the high-side detection current IS1 is greater than the low-side detection current IS2 minus the high-side threshold TH1, the high-voltage short-circuit indication signal S2H is in its second state. In one embodiment, the first state of the high-voltage short-circuit indication signal S2H is a low level, indicating that the high-side bus port CANH or the low-side bus port CANL of the CAN bus is short-circuited to the voltage source VCC. The second state of the high-voltage short-circuit indication signal is a high level, indicating that the high-side bus port CANH or the low-side bus port CANL of the CAN bus is not short-circuited to the voltage source VCC.

[0027] Figure 2B A schematic diagram of a CAN transceiver circuit 201 according to an embodiment of the present invention is provided. The CAN transceiver circuit 201 includes a high-side bus port CANH, a low-side bus port CANL, a high-side switch K1, a low-side switch K2, a first current detection circuit 1, and a second current detection circuit 2. The first current detection circuit 1 includes a third transistor M3. The second current detection circuit 2 includes a fourth transistor M4. The source terminal of the third transistor M3 is coupled to a voltage source VCC, the gate terminal of the third transistor M3 is coupled to the control terminal of the high-side switch K1, and the drain terminal of the third transistor M3 outputs a high-side detection current IS1. The source terminal of the fourth transistor M4 is coupled to reference ground GND, the gate terminal of the fourth transistor M4 is coupled to the control terminal of the low-side switch K2, and the drain terminal of the fourth transistor M4 outputs a low-side detection current IS2. In one embodiment, the third transistor M3 is a P-type MOSFET, and the fourth transistor M4 is an N-type MOSFET.

[0028] exist Figure 2B In the CAN transceiver circuit, the drain of the third transistor M3 is coupled to the drain of the fourth transistor M4, forming a low-voltage short-circuit detection node W2. The low-voltage short-circuit detection node W2 generates a low-voltage short-circuit indication signal S2L based on the high-side detection current IS1 and the low-side detection current IS2. When the high-side detection current IS1 is greater than the low-side detection current IS2 plus the low-side threshold TH2, the low-voltage short-circuit indication signal S2L is in a first state; when the high-side detection current IS1 is less than the low-side detection current IS2 plus the low-side threshold TH2, the second short-circuit signal S2L is in a second state. In one embodiment, the first state of the low-voltage short-circuit indication signal S2L is a high-level state, indicating that the high-side bus port CANH or the low-side bus port CANL of the CAN bus is short-circuited to the reference ground GND. The second state of the low-voltage short-circuit indication signal S2L is a high-level state, indicating that the high-side bus port CANH or the low-side bus port CANL of the CAN bus is not short-circuited to the reference ground GND.

[0029] Figure 3A schematic diagram of a CAN transceiver circuit 300 according to an embodiment of the present invention is provided. The CAN transceiver circuit 300 can simultaneously set a high-voltage short-circuit detection node W1 and a low-voltage short-circuit detection node W2 to detect short circuit conditions of the CAN bus. The high-voltage short-circuit detection node W1 is used to detect the CAN bus short-circuiting to the voltage source VCC, and the low-voltage short-circuit detection node W2 is used to detect the CAN bus short-circuiting to the reference ground GND.

[0030] exist Figure 3 In this embodiment, the CAN transceiver circuit 300 includes a high-side bus port CANH, a low-side bus port CANL, a high-side switch K1, a low-side switch K2, a first current detection circuit 1, and a second current detection circuit 2. The first current detection circuit 1 includes a first transistor M1 and a third transistor M3. The second current detection circuit 2 includes a second transistor M2 and a fourth transistor M4. The sources of the first transistor M1 and the third transistor M3 are coupled to a voltage source VCC, and their gates are coupled to the control terminal of the high-side switch K1. The drains of the first transistor M1 and the third transistor M3 output a high-side detection current IS1. The sources of the second transistor M2 and the fourth transistor M4 are coupled to a reference ground GND, and their gates are coupled to the control terminal of the low-side switch K2. The drains of the second transistor M2 and the fourth transistor M4 output a low-side detection current IS2. Figure 3 In the circuit, the drain of the second transistor M2 is coupled to the drain of the first transistor M1 to form a high-voltage short-circuit detection node W1. The drain of the third transistor M3 is coupled to the drain of the fourth transistor M4 to form a low-voltage short-circuit detection node W2.

[0031] continue Figure 3 The CAN transceiver circuit 300 includes a first current source Ia and a second current source Ib. The first current source Ia is coupled between the voltage source VCC and the high-voltage short-circuit detection node W1. The second current source Ib is coupled between the low-voltage short-circuit detection node W2 and the reference ground GND. In one embodiment, the current value output by the first current source Ia is equal to the high-side threshold TH1. In another embodiment, the current value output by the second current source Ib is equal to the low-side threshold TH2.

[0032] When the high-side detection current IS1 is less than the low-side detection current IS2 minus the high-side threshold TH1, the high-voltage short-circuit indication signal S2H is in its first state. When the high-side detection current IS1 is greater than the low-side detection current IS2 minus the high-side threshold TH1, the high-voltage short-circuit indication signal S2H is in its second state. In one embodiment, the first state of the high-voltage short-circuit indication signal S2H is a high-level state, indicating that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the voltage source VCC. The second state of the high-voltage short-circuit indication signal S2H is a low-level state, indicating that the high-side bus port CANH or the low-side bus port CANL is not short-circuited to the voltage source VCC. When the high-side detection current IS1 is greater than the low-side detection current IS2 plus the low-side threshold TH2, the low-voltage short-circuit indication signal S2L is in its first state. When the high-side detection current IS1 is less than the low-side detection current IS2 plus the high-side threshold TH2, the low-voltage short-circuit indication signal S2L is in its second state. In one embodiment, the first state of the low-voltage short-circuit indication signal S2L is a high-level state, indicating that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the reference ground GND. The second state of the high-voltage short-circuit indication signal S2L is a low-level state, indicating that the high-side bus port CANH or the low-side bus port CANL is not short-circuited to the reference ground GND.

[0033] exist Figure 3 In this embodiment, the CAN transceiver circuit 300 further includes a first operational amplifier A1 and a second operational amplifier A2. The first input terminal of the first operational amplifier A1 is coupled to the second terminal of the high-side switch K1, the output terminal of the first operational amplifier A1 is coupled to the drain terminal of the first transistor M1, and the output terminal of the first operational amplifier A1 is also coupled to its own second input terminal. The first input terminal of the second operational amplifier A2 is coupled to the second terminal of the high-side switch K1, the output terminal of the second operational amplifier A2 is coupled to the drain terminal of the third transistor M3, and the output terminal of the second operational amplifier A2 is also coupled to its own second input terminal. The first operational amplifier A1 and the second operational amplifier A2 output the same voltage value, controlling the voltage at the drain terminal of the first transistor M1 and the drain terminal of the third transistor M3 to be the same.

[0034] Figure 4 A schematic diagram of a CAN transceiver circuit 400 according to another embodiment of the present invention is provided. Compared to Figure 3 The difference between the CAN transceiver circuit 300 and the CAN transceiver circuit 300 is that... Figure 4 The CAN transceiver circuit 400 also includes a high-side withstand voltage circuit 3 and a low-side withstand voltage circuit 4. These circuits protect the CAN transceiver circuit when the voltages at both the high-side bus port CANH and the low-side bus port CANL are high. Figure 4In one embodiment, the high-side withstand voltage circuit 3 has a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of the high-side switch K1, and the second terminal is coupled to the high-side bus port CANH. The low-side withstand voltage circuit 4 has a first terminal and a second terminal, wherein the first terminal is coupled to the low-side bus port CANL, and the second terminal is coupled to the first terminal of the low-side switch K2. In one embodiment, the high-side withstand voltage circuit 3 includes a power diode. In another embodiment, the high-side withstand voltage circuit 3 includes a laterally diffused field-effect transistor. In the CAN transceiver circuit 400, the high-side withstand voltage circuit 3 and the low-side withstand voltage circuit 4 will have a high-side leakage current Isub1 and a low-side leakage current Isub2 due to parasitic effects.

[0035] exist Figure 4 In this embodiment, the CAN transceiver circuit 400 further includes a parasitic current mirror circuit 5, which includes a first mirror transistor M5 and a second mirror transistor M6. The source terminal of the first mirror transistor M5 is coupled to the voltage source VCC, and its gate terminal is coupled to the control terminal of the high-side switch K1. The source terminal of the second mirror transistor M6 is coupled to the reference ground GND, its gate terminal is coupled to the control terminal of the low-side switch K2, and its drain terminal is coupled to the drain terminal of the first mirror transistor M5. The current flowing through the first mirror transistor M5 is the high-side mirror current IH, and the current flowing through the second mirror transistor M6 is the low-side mirror current IL. Parasitic current mirror circuit 5 generates a high-side mirror current IH based on the high-side current I1, and a low-side mirror current IL based on the low-side current I2. It then generates a regulating current IOS based on both the high-side mirror current IH and the low-side mirror current IL. The magnitude of the regulating current IOS is related to the high-side current I1, the low-side current I2, the high-side leakage current Isub1, and the low-side leakage current Isub2 as follows: IOS = IH - IL = (I1 - I2) / M = (Isub1 + Isub1) / M, where M is the mirror ratio between the parasitic current mirror circuit 5 and the high-side switch K1. Figure 4 In the CAN transceiver circuit 400, there are also a third current source Ic and a fourth current source Id, wherein the magnitude of the current output by the third current source Ic and the fourth current source Id is equal to the magnitude of the adjustment current IOS.

[0036] exist Figure 4In the illustrated embodiment, when the high-side bus port CANH or the low-side bus port CANL is short-circuited to the voltage source VCC, the high-side detection current IS1 is less than the low-side detection current IS2 minus the first comparison value TB1. When the high-side bus port CANH or the low-side bus port CANL is short-circuited to the reference ground GND, the high-side detection current IS1 is greater than the low-side detection current IS2 plus the second comparison value TB2. Both the first comparison value TB1 and the second comparison value TB2 are related to the regulating current IOS. In one embodiment, the first comparison value TB1 is equal to the high-side threshold TH1 minus the regulating current IOS. In another embodiment, the second comparison value TB2 is equal to the low-side threshold TH2 plus the regulating current IOS.

[0037] Figure 5 A schematic diagram of the CAN transceiver circuit 500 according to another embodiment of the present invention is provided. Figure 5 In the embodiment, the high-side withstand voltage circuit 3 includes a first withstand voltage diode VD1, and the low-side withstand voltage circuit 4 includes a second withstand voltage diode VD2. Due to parasitic effects, the first power diode VD1 has a first parasitic transistor P1, and the second power diode VD2 has a second parasitic transistor P2. Figure 5 In the diagram, the current flowing through the high-side switch K1 is the high-side current I1, the current flowing through the low-side switch K2 is the low-side current I2, the current flowing through the first parasitic transistor P1 is the high-side leakage current Isub1, and the current flowing through the second parasitic transistor P2 is the low-side leakage current Isub2. Figure 5 In one embodiment shown, the first mirror transistor M5 is a P-type MOS transistor, and the second mirror transistor M6 is an N-type MOS transistor.

[0038] exist Figure 5 In this embodiment, the parasitic current mirror circuit 5 also includes a seventh transistor M7. The source of the seventh transistor M7 is coupled to reference ground GND, its drain is coupled between the first mirror transistor M5 and the second mirror transistor M6, and its gate is coupled to its own drain. In one embodiment, the current flowing through the seventh transistor M7 is the regulating current IOS, where IOS = I1 - I2 = (Isub1 + Isub2) / M. Here, M represents the mirror ratio between the high-side switch K1 and the first mirror transistor M5, which is also the mirror ratio between the low-side switch K2 and the second mirror transistor M6. In one embodiment, the magnitude of the regulating current IOS is equal to the magnitude of the third current source Ic, which is equal to the magnitude of the fourth current source Id. In one embodiment, the seventh transistor M7 is an N-type MOS transistor.

[0039] Using the CAN transceiver circuit in one embodiment of the present invention, it can determine that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the voltage source VCC when the high-side detection current IS1 is less than the low-side detection current IS2 minus the high-side threshold TH1, and it can determine that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the reference ground GND when the high-side detection current IS1 is greater than the low-side detection current IS2 plus the low-side threshold TH2.

[0040] Using the CAN transceiver circuit in another embodiment of the present invention, it can be determined that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the voltage source VCC when the high-side detection current IS1 is less than the low-side detection current IS2 minus the first comparison value TB1; and it can be determined that the high-side bus port CANH or the low-side bus port CANL is short-circuited to the reference ground GND when the high-side detection current IS1 is greater than the low-side detection current IS2 plus the second comparison value TB2. This method of determining the short circuit condition of the CAN bus allows for precise location of the problem during CAN bus repair.

[0041] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0042] The specific embodiments described above are merely illustrative of the invention. These embodiments are not exhaustive and are not intended to limit the scope of the invention. Variations and modifications to the disclosed embodiments are possible, and other feasible alternative embodiments and equivalent variations of elements in the embodiments can be understood by those skilled in the art. Other variations and modifications to the embodiments disclosed in this invention do not depart from the spirit of the invention and the scope of protection defined by the claims.

[0043] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A CAN transceiver circuit, comprising: High-side bus port, outputs high-side signal; Low-side bus port outputs low-side signals; A high-side switch has a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a power supply, the control terminal receives a high-side control signal, and the current flowing through the high-side switch is the high-side current. A high-side withstand voltage circuit has a first terminal and a second terminal, wherein the first terminal is coupled to the second terminal of a high-side switch and the second terminal is coupled to a high-side bus port. A low-side withstand voltage circuit has a first terminal and a second terminal, wherein the first terminal is coupled to a low-side bus port. A low-side switch has a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of a low-side withstand voltage circuit, the second terminal is coupled to a reference ground, and the control terminal receives a low-side control signal, wherein the current flowing through the low-side switch is the low-side current. The first current detection circuit is coupled to the high-side switch and generates a high-side detection current based on the high-side current, wherein the high-side detection current is proportional to the high-side current. The second current detection circuit is coupled to the low-side switch and generates a low-side detection current based on the low-side current, wherein the low-side detection current is proportional to the low-side current. as well as A parasitic current mirror circuit is coupled to the high-side switch and the low-side switch and generates a regulating current, the magnitude of which is related to the difference between the high-side current and the low-side current. When either the high-side bus port or the low-side bus port is shorted to a voltage source, the high-side detection current is less than the low-side detection current minus a first comparison value, and the first comparison value is equal to the high-side threshold minus the adjustment current.

2. The CAN transceiver circuit according to claim 1, wherein when the high-side bus port or the low-side bus port is shorted to the reference ground, the high-side detection current is greater than the low-side detection current plus the second comparison value, and the second comparison value is equal to the low-side threshold plus the adjustment current.

3. The CAN transceiver circuit according to claim 2, wherein the first current detection circuit includes a first transistor, the source terminal of the first transistor is coupled to a power supply, the gate terminal of the first transistor is coupled to a control terminal of a high-side switch, and the drain terminal of the first transistor outputs a high-side detection current; wherein the second current detection circuit includes a second transistor, the source terminal of the second transistor is coupled to a reference ground, the gate terminal of the second transistor is coupled to a control terminal of a low-side switch, and the drain terminal of the second transistor outputs a high-side detection current.

4. The CAN transceiver circuit according to claim 2, wherein the parasitic current mirror circuit comprises: The first mirror transistor has its source terminal coupled to the supply voltage and its gate terminal coupled to the control terminal of the high-side switch. The second mirror transistor has its source coupled to reference ground, its gate coupled to the control terminal of the low-side switch, and its drain coupled to the drain of the first mirror transistor.

5. The CAN transceiver circuit according to claim 2, wherein the high-side withstand voltage circuit includes a power diode or a lateral diffused field-effect transistor.

6. The CAN transceiver circuit according to claim 2 further generates a high-voltage short-circuit indication signal and a low-voltage short-circuit indication circuit based on the high-side detection current and the low-side detection current, wherein when the high-side detection current is less than the low-side detection current minus a first comparison value, the high-voltage short-circuit indication signal is in a first state; when the high-side detection current is greater than the low-side detection current minus the first comparison value, the high-voltage short-circuit indication signal is in a second state; when the high-side detection current is greater than the low-side detection current plus a second comparison value, the low-voltage short-circuit indication signal is in a first state; when the high-side detection current is less than the low-side detection current plus a second comparison value, the low-voltage short-circuit indication signal is in a second state.

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