An adaptive vehicle wheel speed sensor interface protection circuit

Abstract

The present invention provides an adaptive vehicle wheel speed sensor interface protection circuit, comprising a Hall wheel speed sensor drive circuit, a current sampling circuit, and an adaptive current comparison circuit. The Hall wheel speed sensor drive circuit is connected to the Hall wheel speed sensor and outputs a drive current to the Hall wheel speed sensor. The current sampling circuit samples the sensor current of the Hall wheel speed sensor. The adaptive current comparison circuit compares the sensor current with a reference current and, based on the comparison result, adjusts the reference current to equal the sensor current. This allows the sensor current to be quickly and accurately determined based on the reference current value, used to determine the wheel speed.

Description

Technical Field

[0001] The present invention relates to the technical field of wheel speed sensors, and in particular to an adaptive vehicle wheel speed sensor interface protection circuit. Background Art

[0002] Wheel speed sensors play a vital role in modern cars. Their importance and role are reflected in many aspects:

[0003] (1) Anti-lock Braking System (ABS): Wheel speed sensors are core components of ABS, monitoring the rotational speed of each wheel in real time. When the vehicle brakes suddenly, the sensors send data to the ABS control unit, which adjusts the brake pressure to prevent the wheels from locking, ensuring that the vehicle maintains steering control and the shortest braking distance.

[0004] (2) Electronic Stability Program (ESP / ESC): ESP uses wheel speed information to detect whether the vehicle is slipping or losing control. By adjusting engine output and braking force on individual wheels, ESP helps the driver maintain vehicle stability and trajectory.

[0005] (3) Traction Control System (TCS): During acceleration, TCS monitors the rotation of the wheels through wheel speed sensors to prevent wheel slippage, ensure effective power transmission to the ground, and improve stability during starting and acceleration.

[0006] (4) Automatic transmission control: In automatic transmission vehicles, wheel speed information is used in the shift logic to ensure smooth gear changes at appropriate speeds and accelerations.

[0007] (5) Odometer and speedometer: The wheel speed sensor directly provides vehicle speed information, drives the speed display on the instrument panel, and ensures the accuracy of the speed reading.

[0008] (6) Vehicle dynamic management: Advanced driver assistance systems (ADAS), including adaptive cruise control and lane keeping assist, all require accurate wheel speed data to achieve intelligent vehicle control.

[0009] (7) Tire pressure monitoring assistance: Although not a direct function, the inconsistency of wheel speed can serve as an indirect indication of abnormal tire pressure and assist in diagnosing tire problems.

[0010] Hall-effect wheel speed sensors are common on the market. They contain a Hall element. When the magnetic field generated by a permanent magnet passes through the Hall element, if there is a rotating ring gear near the Hall element, the edge of the tooth changes the magnetic flux passing through the Hall element. This change in magnetic flux causes a voltage change within the Hall element, generating a Hall voltage. This voltage is proportional to the ring gear's rotational speed. Through the load circuit, the output signal is converted into a digital pulse with a stable amplitude, unaffected by vehicle speed, and suitable for direct processing by the electronic control unit. Hall-effect wheel speed sensors typically output a current square wave signal of 7mA to 14mA, which can accurately detect the state of the wheel at low speed or even at near standstill.

[0011] The fundamental principle behind the common Hall-effect wheel speed sensor solution on the market is to sample the current generated by the Hall-effect wheel speed sensor to determine the current wheel speed. However, existing wheel speed sensor interface circuits lack systematic protection circuits and fail to account for abnormalities caused by various operating conditions, potentially leading to safety accidents. They also suffer from issues such as high power consumption, low accuracy, and slow judgment speed. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a wheel speed sensor interface circuit which is safe, has low power consumption, high precision and fast judgment speed.

[0013] To solve the above technical problems, the present invention provides an adaptive vehicle wheel speed sensor interface protection circuit, comprising a Hall wheel speed sensor drive circuit, a current sampling circuit, and an adaptive current comparison circuit, wherein:

[0014] The Hall wheel speed sensor driving circuit includes a driving power supply terminal, a ground terminal, a high-side interface and a low-side interface respectively connected to the two ends of the Hall wheel speed sensor; a high-side power tube and a positive voltage anti-reverse protection tube are connected between the high-side interface and the driving power supply terminal, and the high-side power tube is connected to the reference current through a first current mirror structure. The circuit also includes a first comparator, whose positive-phase input terminal is connected to the high-side interface, the negative-phase input terminal is connected to the power supply terminal, and the output terminal is connected to the positive voltage anti-reverse protection tube; a low-side power tube and a negative voltage anti-reverse protection tube are connected between the low-side interface and the ground terminal, the low-side power tube is connected to the reference current through a second current mirror structure, and the negative voltage anti-reverse protection tube is connected to the turn-on voltage. The circuit also includes a second comparator, whose positive-phase input terminal is connected to the reference voltage, the negative-phase input terminal is connected to the low-side interface, and the output terminal is connected to the MCU chip. The reference voltage is lower than the driving power supply terminal voltage.

[0015] The current sampling circuit includes a third current mirror structure, a digital circuit, and a fourth current mirror structure. The sensor current of the Hall wheel speed sensor is mirrored by the third current mirror structure and output to the adaptive current comparison circuit. The digital circuit generates a reference current. The fourth current mirror structure mirrors the reference current and outputs it to the adaptive current comparison circuit.

[0016] The adaptive current comparison circuit includes a sensor current input terminal, a reference current input terminal, a current magnitude comparison branch, a level output terminal, a current difference comparison branch and a difference output terminal. The sensor current input terminal is connected to the sensor current through a third current mirror structure, and the reference current input terminal is connected to the reference current through a fourth current mirror structure. After the sensor current input terminal and the reference current input terminal are connected, they are connected to the level output terminal through the current magnitude comparison branch, and are connected to the difference output terminal through the current difference comparison branch. The level output terminal and the difference output terminal are connected to the digital circuit. The adaptive current comparison circuit compares the sensor current with the reference current through the current magnitude comparison branch and the current difference comparison branch, outputs the current magnitude comparison result to the digital circuit through the level output terminal, and outputs the comparison difference to the digital circuit through the difference output terminal.

[0017] Furthermore, the first current mirror structure includes a first operational amplifier, the positive input terminal of the first operational amplifier is connected to the output stage device of the first current mirror structure, the negative input terminal is connected to the input stage device of the first current mirror structure, and the output terminal is connected to the input terminal of the first current mirror structure via a MOS tube.

[0018] Furthermore, the second current mirror structure includes a second operational amplifier, the positive input terminal of the second operational amplifier is connected to the output stage device of the second current mirror structure, the negative input terminal is connected to the input stage device of the second current mirror structure, and the output terminal is connected to the input terminal of the second current mirror structure via a MOS tube.

[0019] Furthermore, the third current mirror structure includes a third operational amplifier, the positive input terminal of the third operational amplifier is connected to the input stage device of the third current mirror structure, the negative input terminal is connected to the output stage device of the third current mirror structure, and the output terminal is connected to the output terminal of the third current mirror structure via a MOS tube.

[0020] Furthermore, the ratio of the channel width of the input stage device to the channel width of the output stage device of the third current mirror structure is 100:1.

[0021] Furthermore, the adaptive current comparison circuit includes a comparison terminal, and the sensor current input terminal and the reference current input terminal are specifically connected to the level output terminal through the current magnitude comparison branch after being connected at the comparison terminal, and are connected to the difference output terminal through the current difference comparison branch.

[0022] The present invention has the following beneficial effects: in the Hall wheel speed sensor drive circuit, when the high-side interface voltage is greater than the drive power supply end, the first comparator outputs a high level to turn off the positive voltage reverse protection tube, preventing the external high voltage of the high-side interface from flowing to the drive power supply end and causing damage to the circuit; when the power supply is reversed, a large current will flow from the ground end to the drive power supply end. At this time, the low-side interface is equivalent to connecting the drive power supply end. Since the reference voltage is lower than the drive power supply end voltage, the second comparator outputs a low level, and the second comparator can detect the reverse power supply and send an error signal to the MCU chip for the MCU chip to make start and stop decisions. In this way, the Hall wheel speed sensor drive circuit can solve the abnormal problems caused by excessive external voltage and reverse power supply, thereby improving system safety. In the current sampling circuit, the sensor current can be scaled by adjusting the mirror ratio of the third current mirror structure to reduce current power consumption. In the adaptive current comparison circuit, the sensor current is compared with the reference current through the current magnitude comparison branch and the current difference comparison branch. The current magnitude comparison result is output to the digital circuit through the level output terminal, and the comparison difference is output to the digital circuit through the difference output terminal. This allows the digital circuit to quickly find the approach direction that makes the reference current equal to the sensor current based on the comparison result, and to quickly and accurately adjust the reference current generated by the digital circuit based on the comparison difference so that the reference current is equal to the sensor current. In this way, the sensor current can be quickly and accurately obtained based on the reference current value to determine the wheel speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the circuit schematic diagram of the adaptive vehicle wheel speed sensor interface protection circuit.

[0024] Figure 2 This is the circuit schematic diagram of the Hall wheel speed sensor drive circuit.

[0025] Figure 3 This is the circuit schematic diagram of the current sampling circuit.

[0026] Figure 4 This is the circuit schematic diagram of the adaptive current comparison circuit. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific embodiments.

[0028] Adaptive vehicle wheel speed sensor interface protection circuit Figure 1As shown, the device includes a Hall wheel speed sensor drive circuit, a current sampling circuit, and an adaptive current comparison circuit. The Hall wheel speed sensor drive circuit is connected to the Hall wheel speed sensor and outputs a drive current to the Hall wheel speed sensor. The current sampling circuit samples the sensor current of the Hall wheel speed sensor. The adaptive current comparison circuit compares the sensor current with a reference current and adjusts the reference current to equal the sensor current based on the comparison result. This allows the sensor current to be quickly and accurately determined based on the reference current value, which is used to determine the wheel speed.

[0029] Hall wheel speed sensor drive circuit Figure 2 As shown, it includes a driving power supply terminal VPRE, a ground terminal GND, a high-side interface RSUH and a low-side interface RSUL. The high-side interface RSUH and the low-side interface RSUL are respectively connected to the two ends of the Hall wheel speed sensor to output a driving current to the Hall wheel speed sensor.

[0030] A high-side power transistor m1 and a positive voltage reverse protection transistor m3 are connected between the high-side interface RSUH and the driver power supply terminal VPRE. High-side power transistor m1 receives reference current Iref via a first current mirror structure. This first current mirror structure includes two sets of current mirrors: current mirrors m4 and m5, and current mirrors m2 and m1. Current mirrors m4 and m5 include MOS transistors m4 and m5. MOS transistor m4 is an input-stage device, with its drain connected to the reference current Iref and its source grounded. Its gate short-circuit the drain and then connected to the gate of MOS transistor m5. MOS transistor m5 is an output-stage device, with its gate connected to the gate of MOS transistor m4 and its drain connected to the drain of MOS transistor m2 via MOS transistors m27 and m28. Its source is grounded. The current mirrors m2 and m1 include a MOS transistor m2 and a high-side power transistor m1. The MOS transistor m2 is an input-stage device, with its drain connected to the drain of the MOS transistor m5 via the MOS transistors m27 and m28, its source connected to the driving power supply terminal VPRE via the MOS transistor m3, and its gate connected to the gate of the high-side power transistor m1 after the drain is short-circuited by the MOS transistor m28. The high-side power transistor m1 is an output-stage device, with its gate connected to the gate of the MOS transistor m2, its drain connected to the high-side interface RSUH, and its source connected to the driving power supply terminal VPRE via the MOS transistor m3. To enhance the matching between MOS transistor m2 and high-side power transistor m1, a first operational amplifier, Opamp1, is added to the first current mirror structure. Its non-inverting input is connected to the drain of high-side power transistor m1, its negative input is connected to the drain of MOS transistor m2, and its output is connected to the gate of MOS transistor m28. Specifically, the positive input of the first operational amplifier, Opamp1, is connected to the output-stage components of the first current mirror structure, its negative input is connected to the input-stage components of the first current mirror structure, and its output is connected to the input of the first current mirror structure via MOS transistor m28. This ensures that the ratio of the current flowing through MOS transistor m2 to the current flowing through high-side power transistor m1 is approximately equal to the ratio of their respective channel widths. In this way, the reference current Iref, mirrored by MOS transistors m4 and m5, serves as the tail current of MOS transistor m2 and the current-limiting reference for high-side power transistor m1, making the high-side current limit more accurate. The current limit value is Ilim_hs, calculated as follows: Wherein, Wm1 is the channel width of the high-side power transistor m1, Wm2 is the channel width of the MOS transistor m2, and Iref is the reference current.

[0031] The Hall effect wheel speed sensor driver circuit also includes a first comparator comp_stb, whose positive input is connected to the high-side interface RSUH, its negative input is connected to the power supply VPRE, and its output is connected to the gate of the positive voltage reverse protection transistor m3. The positive voltage reverse protection transistor m3's source is connected to the drive power supply VPRE, and its drain is connected to the high-side interface RSUH via the high-side power transistor m1. When the voltage at the high-side interface RSUH exceeds the drive power supply VPRE, the first comparator comp_stb outputs a high level, shutting off the positive voltage reverse protection transistor m3. This prevents the external high voltage from the high-side interface RSUH from flowing to the drive power supply VPRE and potentially damaging the circuit. This prevents abnormalities caused by excessive external voltage and improves system safety.

[0032] A low-side power transistor m8 and a negative voltage reverse protection transistor m6 are connected between the low-side interface RSUL and the ground terminal GND. The low-side power transistor M8 is connected to the reference current Iref through a second current mirror structure. The second current mirror structure includes a MOS transistor m7 and a low-side power transistor m8. The MOS transistor m7 is an input-stage device of the second current mirror structure. Its drain is connected to the reference current Iref via a MOS transistor m29, its source is grounded, and its gate is connected to the gate of the low-side power transistor m8 after the drain is short-circuited by the MOS transistor m29. The low-side power transistor m8 is an output-stage device of the second current mirror structure. Its gate is connected to the gate of the MOS transistor m7, its drain is connected to the low-side interface RSUL via the negative voltage reverse protection transistor m6, and its source is grounded. To enhance the matching between MOS transistor m7 and low-side power transistor m8, a second operational amplifier, Opamp2, is added to the second current mirror structure. Its non-inverting input is connected to the drain of low-side power transistor m8 via MOS transistor m30, its negative input is connected to the drain of MOS transistor m7, and its output is connected to the gate of MOS transistor m29. Specifically, the non-inverting input of the second operational amplifier, Opamp2, is connected to the output-stage components of the second current mirror structure, its negative input is connected to the input-stage components of the second current mirror structure, and its output is connected to the input of the second current mirror structure via MOS transistor m29. This ensures that the ratio of the current flowing through MOS transistor m7 to the current flowing through low-side power transistor m8 is approximately equal to the ratio of their respective channel widths. This reference current, Iref, serves as the current limit reference for low-side power transistor m8, making the low-side current limit more accurate. The low-side current limit is Ilim_ls, calculated using the following formula: Among them, Wm8 is the channel width of the low-side power transistor m8, Wm7 is the channel width of the MOS transistor m7, and Iref is the reference current.

[0033] The gate of the negative voltage reverse protection transistor m6 is connected to the enable voltage Ibias, the drain is connected to the low-side interface RSUL, and the source is grounded via the low-side power transistor m8. Resistor R1 is connected between the gate and drain of the negative voltage reverse protection transistor m6. The enable voltage Ibias flows through resistor R1, turning on the negative voltage reverse protection transistor m6. The Hall effect wheel speed sensor drive circuit also includes a second comparator comp_stg, whose positive input terminal is connected to the reference voltage Vref, its negative input terminal is connected to the low-side interface RSUL, and its output terminal STG is connected to the MCU chip. The reference voltage Vref is lower than the voltage at the driver power supply terminal VPRE. When the power supply is connected in a positive direction, the low-side interface RSUL is grounded, and the second comparator comp_stg outputs a high level. When the power supply is connected in a reverse direction, a large current flows from the ground terminal GND to the driver power supply terminal VPRE. At this time, the low-side interface RSUL is equivalent to being connected to the driver power supply terminal VPRE. Since the reference voltage Vref is lower than the voltage of the driver power supply terminal VPRE, the second comparator comp_stg outputs a low level. The second comparator comp_stg can detect the reverse power supply and send an error signal to the MCU chip, allowing the MCU chip to make start-stop decisions. In this way, the Hall wheel speed sensor drive circuit can solve the abnormal problem caused by reverse power supply connection and improve system safety.

[0034] Current sampling circuit such as Figure 3As shown, it includes a third current mirror structure, a digital circuit 10Bit_DAC, and a fourth current mirror structure. The third current mirror structure includes two sets of current mirrors: current mirrors m8 and m9, and current mirrors m10 and m11. Current mirrors m8 and m9 include a low-side power transistor m8 and a MOS transistor m9. The low-side power transistor m8 is an input-stage device, and the MOS transistor m9 is an output-stage device. Its gate is connected to the gate of the low-side power transistor m8, its drain is connected to the drain of the MOS transistor m10 via the MOS transistor m31, and its source is grounded. To enhance the matching between the low-side power transistor m8 and the MOS transistor m9, a third operational amplifier Opamp3 is added to the third current mirror structure. The third operational amplifier Opamp3 has a positive input connected to the drain of the low-side power transistor m8 via the MOS transistor m30, a negative input connected to the drain of the MOS transistor m9, and an output connected to the gate of the MOS transistor m31. That is, the positive input of the third operational amplifier Opamp3 is connected to the input-stage components of the third current mirror structure, the negative input is connected to the output-stage components of the third current mirror structure, and the output is connected to the output of the third current mirror structure via the MOS transistor m31. This ensures that the ratio of the current flowing through the low-side power transistor m8 to the current flowing through the MOS transistor m9 is approximately equal to the ratio of their channel widths. Current mirrors m10 and m11 include MOS transistors m10 and m11. MOS transistor m10 is an input-stage device, with its drain connected to the drain of MOS transistor m9 via MOS transistor m31. Its source is connected to the power supply VCC. Its gate, short-circuited with the drain, is connected to the gate of MOS transistor m11. MOS transistor m11 is an output-stage device, with its gate connected to the gate of MOS transistor m10, its drain connected to the adaptive current comparator circuit, and its source connected to the power supply VCC. The Hall effect wheel speed sensor driver circuit drives the Hall effect wheel speed sensor to generate a sensor current. This sensor current flows through the low-side power transistor m8, is mirrored by the third current mirror structure, and is output to the adaptive current comparator circuit.

[0035] In this embodiment, the ratio of the channel width of the low-side power transistor m8 to the channel width of the MOS transistor m9 is 100:1. Therefore, the ratio of the current flowing through the low-side power transistor m8 to the current flowing through the MOS transistor m9 is also 100:1. The current is scaled by the MOS transistor m9 to reduce the power consumption of the current.

[0036] The digital circuit 10Bit_DAC generates a reference current and is connected in series between the power supply VCC and the ground terminal GND. The fourth current mirror structure includes a MOS transistor m12 and a MOS transistor m13. MOS transistor m12 is the input-stage component of the fourth current mirror structure. Its drain is connected to the digital circuit 10Bit_DAC, its source is connected to the power supply VCC, and its gate is short-circuited with the drain and then connected to the gate of MOS transistor m13. MOS transistor m13 is the output-stage component of the fourth current mirror structure. Its gate is connected to the gate of MOS transistor m12, its drain is connected to the adaptive current comparator circuit, and its source is connected to the power supply VCC. In this way, the fourth current mirror structure mirrors the reference current generated by the digital circuit 10Bit_DAC and outputs it to the adaptive current comparator circuit.

[0037] The adaptive current comparison circuit includes a sensor current input terminal N1, a reference current input terminal N2, a comparison terminal Comp_in, a current magnitude comparison branch, a level output terminal Sign, a current difference comparison branch and a difference output terminal Error_code <n:0>The current magnitude comparison branch includes MOS transistors m14, m15, m16, m17, m18, m19, and m20, and the current difference comparison branch includes MOS transistors m21, m22, m23, m24, m25, and m26. The sensor current input terminal N1 is connected to the sensor current through a third current mirror structure, and the reference current input terminal N2 is connected to the reference current through a fourth current mirror structure. After the sensor current input terminal N1 and the reference current input terminal N2 are connected at the comparison terminal Comp_in, they are connected to the level output terminal Sign through the current magnitude comparison branch and to the difference output terminal Error_code through the current difference comparison branch. <n:0>, level output terminal Sign and difference output terminal Error code <n:0>Connect the digital circuit 10Bit DAC.

[0038] In the current comparison branch, MOS transistors m14 and m15 form a current mirror structure. MOS transistor m14 is an input-stage device, with its drain connected to the reference current input terminal N2 and its source grounded. Its gate is short-circuited with the drain and then connected to the gate of MOS transistor m15. MOS transistor m15 is an output-stage device, with its gate connected to the gate of MOS transistor m14, its drain connected to the comparison terminal Comp_in, and its source grounded. MOS transistors m16 and m17 form a current mirror structure. MOS transistor m16 is an input-stage device, with its drain connected to the drain of MOS transistor m19 and its source grounded. Its gate is short-circuited with the drain and then connected to the gate of MOS transistor m17. MOS transistor m17 is an output-stage device, with its gate connected to the gate of MOS transistor m16, its drain connected to the drain of MOS transistor m20, and its source grounded. MOS transistor m19 has its source connected to the comparison terminal Comp_in, its drain connected to the drain of MOS transistor m16, and its gate connected to the level output terminal Sign. MOS transistor m20 has its source connected to the comparison terminal Comp_in, its drain connected to the drain of MOS transistor m17, and its gate connected to the level output terminal Sign. MOS transistor m18 has its drain connected to power supply VCC, its source connected to ground, and its gate connected to the comparison terminal Comp_in. The adaptive current comparison circuit compares the sensor current with the reference current through a current magnitude comparison branch and outputs the current magnitude comparison result to the digital circuit 10-bit_DAC through the level output terminal Sign. Based on the comparison result, the digital circuit 10-bit_DAC can quickly determine the direction in which the reference current approaches the sensor current. This determines whether to amplify or reduce the reference current to approximate the sensor current.

[0039] In the current difference comparison branch, MOS transistors m21 and m22 form a current mirror structure. MOS transistor m21 is an input-stage device, with its drain connected to the junction between the drains of MOS transistors m17 and m20, its source connected to the power supply VCC, and its gate short-circuited with the drain and then connected to the gate of MOS transistor m22. MOS transistor m22 is an output-stage device, with its gate connected to the gate of MOS transistor m21, its source connected to the power supply VCC, and its drain connected to the difference output terminal Error_code. <n:0>MOS transistor m23 and MOS transistor m24 form a current mirror structure, wherein MOS transistor m23 is an input-stage device, with its drain connected to the power supply VCC, its source grounded, and its gate short-circuited with the drain and then connected to the gate of MOS transistor m24. MOS transistor m24 is an output-stage device, with its gate connected to the gate of MOS transistor m23, its drain connected to the drain of MOS transistor m22, and its source grounded. The adaptive current comparison circuit compares the sensor current with the reference current through a current difference comparison branch. Specifically, when the sensor current is greater than the reference current, the current I_m11 of the MOS tube m11 is greater than the current I_m13 of the MOS tube m13. At this time, the current of the MOS tube m21 is a comparison difference, specifically I_m21=I_m11-I_m13. The MOS tube m22 mirrors the current of the MOS tube m21 as the input of the current difference comparison branch. When the current is greater than the sensor current reference, the current I_m13 of the MOS tube m13 is greater than the current I_m11 of the MOS tube m11. At this time, the current of the MOS tube m21 is a comparison difference, specifically I_m21=I_m13-I_m11. The MOS tube m22 mirrors the current of the MOS tube m21 as the input of the current difference comparison branch. Then, the error code is output through the difference output terminal Error_code. <n:0>The comparison difference is output to the digital circuit 10Bit_DAC, so that the digital circuit 10Bit_DAC can quickly and accurately adjust the reference current generated by the digital circuit based on the comparison difference, so that the reference current is equal to the sensor current. In this way, the sensor current can be quickly and accurately obtained based on the reference current value to determine the wheel speed.

[0040] In the adaptive current comparison circuit, MOS transistors m21, m22, m23, and m24 form a set of current difference comparison branches, while MOS transistors m26 and m25 form another set of current difference comparison branches. The source of MOS transistor m26 is connected to the power supply VCC, the gate is connected to the gate of MOS transistor m21, and the drain is connected to the difference output terminal Error_code. <n:0>, and the drain of MOS tube m25 is connected to the difference output terminal Error_code <n:0>The gate is connected to the gate of MOS transistor m23, and the source is grounded. Under normal circumstances, the current difference comparison branch formed by MOS transistors m21, MOS transistors m22, MOS transistors m23, and MOS transistors m24 can achieve current difference output. When different accuracy requirements are required, the current difference comparison branch formed by MOS transistors m26 and MOS transistors m25 can be added to meet different accuracy requirements.

[0041] The above is only an embodiment of the present invention and does not limit the scope of patent protection. Those skilled in the art can make non-substantial changes or substitutions based on the present invention and still fall within the scope of patent protection.

Claims

1. An adaptive vehicle wheel speed sensor interface protection circuit, characterized in that: It includes a Hall wheel speed sensor drive circuit, a current sampling circuit and an adaptive current comparison circuit, wherein: The Hall wheel speed sensor driving circuit includes a driving power supply terminal, a ground terminal, a high-side interface and a low-side interface respectively connected to the two ends of the Hall wheel speed sensor; a high-side power tube and a positive voltage anti-reverse protection tube are connected between the high-side interface and the driving power supply terminal, and the high-side power tube is connected to the reference current through a first current mirror structure. The circuit also includes a first comparator, whose positive-phase input terminal is connected to the high-side interface, the negative-phase input terminal is connected to the power supply terminal, and the output terminal is connected to the positive voltage anti-reverse protection tube; a low-side power tube and a negative voltage anti-reverse protection tube are connected between the low-side interface and the ground terminal, the low-side power tube is connected to the reference current through a second current mirror structure, and the negative voltage anti-reverse protection tube is connected to the turn-on voltage. The circuit also includes a second comparator, whose positive-phase input terminal is connected to the reference voltage, the negative-phase input terminal is connected to the low-side interface, and the output terminal is connected to the MCU chip. The reference voltage is lower than the driving power supply terminal voltage. The current sampling circuit includes a third current mirror structure, a digital circuit, and a fourth current mirror structure. The sensor current of the Hall wheel speed sensor is mirrored by the third current mirror structure and output to the adaptive current comparison circuit. The digital circuit generates a reference current. The fourth current mirror structure mirrors the reference current and outputs it to the adaptive current comparison circuit. The adaptive current comparison circuit includes a sensor current input terminal, a reference current input terminal, a current magnitude comparison branch, a level output terminal, a current difference comparison branch and a difference output terminal. The sensor current input terminal is connected to the sensor current through a third current mirror structure, and the reference current input terminal is connected to the reference current through a fourth current mirror structure. After the sensor current input terminal and the reference current input terminal are connected, they are connected to the level output terminal through the current magnitude comparison branch, and are connected to the difference output terminal through the current difference comparison branch. The level output terminal and the difference output terminal are connected to the digital circuit. The adaptive current comparison circuit compares the sensor current with the reference current through the current magnitude comparison branch and the current difference comparison branch, outputs the current magnitude comparison result to the digital circuit through the level output terminal, and outputs the comparison difference to the digital circuit through the difference output terminal.

2. The adaptive vehicle wheel speed sensor interface protection circuit according to claim 1, characterized in that: The first current mirror structure includes a first operational amplifier, wherein the positive input terminal of the first operational amplifier is connected to the output stage device of the first current mirror structure, the negative input terminal is connected to the input stage device of the first current mirror structure, and the output terminal is connected to the input terminal of the first current mirror structure via a MOS tube.

3. The adaptive vehicle wheel speed sensor interface protection circuit according to claim 1, characterized in that: The second current mirror structure includes a second operational amplifier, the non-phase input terminal of the second operational amplifier is connected to the output stage device of the second current mirror structure, the negative input terminal is connected to the input stage device of the second current mirror structure, and the output terminal is connected to the input terminal of the second current mirror structure via a MOS tube.

4. The adaptive vehicle wheel speed sensor interface protection circuit according to claim 1, characterized in that: The third current mirror structure includes a third operational amplifier, wherein the positive input terminal of the third operational amplifier is connected to the input stage device of the third current mirror structure, the negative input terminal is connected to the output stage device of the third current mirror structure, and the output terminal is connected to the output terminal of the third current mirror structure via a MOS tube.

5. The adaptive vehicle wheel speed sensor interface protection circuit according to claim 1, characterized in that: The ratio of the channel width of the input stage device to the channel width of the output stage device of the third current mirror structure is 100:

1.

6. The adaptive vehicle wheel speed sensor interface protection circuit according to claim 1, characterized in that: The adaptive current comparison circuit includes a comparison terminal. The sensor current input terminal and the reference current input terminal are specifically connected to the level output terminal through a current magnitude comparison branch after being connected to the comparison terminal, and are connected to the difference output terminal through a current difference comparison branch.

Images