Automobile brake signal acquisition circuit with self-diagnosis hall chip

Abstract

The application discloses a kind of automobile brake signal acquisition circuits, including Hall chip U1, two-way output MOS unit and reverse conversion circuit;U1 internal integrated Hall induction element, amplification unit, internal reference source and on-chip self-checking circuit, on-chip self-checking circuit completes internal fault detection and generates diagnostic status signal, U1 output position level signal and diagnostic status signal, its OUT pin connects the 6th pin of connector CON1;Two-way output MOS unit receives position level signal, is converted into two-way complementary level signal and is sent to the 3rd, 4th pin of CON1, when Hall chip detects internal fault, OUT pin outputs tick pulse fault waveform, is exported externally via the 6th pin of CON1.The circuit realizes chip fault identification output by the on-chip self-checking circuit of Hall chip, reduces external MCU diagnostic burden, and improves brake switch working reliability.

Description

Technical Field

[0001] This invention relates to the field of automotive electronic brake sensing technology, and in particular to an automotive brake signal acquisition circuit with a self-diagnostic Hall chip. Background Technology

[0002] The brake pedal switch is a critical component in automobiles, transmitting information about whether the brake pedal is depressed to the Electronic Control Unit (ECU) in the form of an electrical signal. It is used for operations such as stopping cruise control and disengaging the torque converter. Traditional mechanical brake switches use metal contacts for switching on and off; frequent use causes contact wear and adhesion, resulting in a short lifespan and no fault diagnosis capabilities. Existing single-Hall brake switches rely solely on the Hall chip, which only outputs a magnetic field sensing signal. The chip itself has no built-in diagnostics, and all fault detection depends entirely on external MCU software. When the Hall chip's internal circuitry fails—including damage to the Hall sensor, amplifier malfunction, or on-chip reference source drift—the MCU can only see the abnormal output level and cannot distinguish whether the failure is due to the Hall chip itself, an external open circuit, or a magnetic field anomaly, leading to vague fault localization. To achieve fault detection, the MCU needs to add a large amount of diagnostic sampling logic, consuming significant computing power, increasing software complexity, and raising the risk of software failure. Some failure modes involve damage to the Hall sensor itself. Such failures are difficult for external MCUs to identify. Single-point failures may cause incorrect output of the braking signal, which is detrimental to the basic functional safety of ISO26262. External circuit diagnosis requires additional sampling resistors and voltage divider circuits, which increases cost and PCB area. Furthermore, the internal reference of the Hall chip drifts under high and low temperatures. Conventional external MCU diagnosis cannot identify internal reference source failures and can only identify abnormal final output results.

[0003] Therefore, existing single-Hall brake switch fault detection relies on external MCU software, which makes fault location unclear and consumes MCU computing power; some internal chip failures are difficult to identify, and hardware diagnosis requires additional peripheral devices, which is costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides an automotive brake signal acquisition circuit with a self-diagnostic Hall chip. The on-chip self-test of the Hall chip enables chip fault identification and output, reducing the diagnostic burden on the external MCU. At the same time, it eliminates mechanical contacts and improves the reliability of the brake switch.

[0005] The technical solution of the present invention: a vehicle braking signal acquisition circuit with a self-diagnostic Hall chip, comprising a Hall chip U1, a dual-output MOS unit, and an inverting conversion circuit; The Hall chip U1 integrates a Hall sensor, an amplification unit, an internal reference source, and an on-chip self-test circuit. The on-chip self-test circuit is used to perform fault detection inside the Hall chip U1 and generate a built-in diagnostic status signal. The Hall chip U1 is used to output two signals, namely a position level signal and a built-in diagnostic status signal; the OUT pin of the Hall chip U1 is electrically connected to pin 6 of connector CON1. The dual-output MOS unit is used to receive the position level signal output by the Hall chip U1 and convert it into two complementary level signals. The two complementary level signals are respectively sent to pin 3 and pin 4 of connector CON1. The inverting conversion circuit is used to output a mutual exclusion logic signal; The Hall chip U1 is positioned on a U-shaped magnet. When the external iron block is far from the magnetic field sensing position, pin 3 of connector CON1 outputs a high level, and pin 4 of connector CON1 outputs a low level. When the external iron block is close to the magnetic field sensing position, pin 3 of connector CON1 outputs a low level, and pin 4 of connector CON1 outputs a high level. When the Hall chip U1 detects an internal fault through the on-chip self-test circuit, the OUT pin of the Hall chip U1 outputs a tick pulse fault waveform, which is then output externally through pin 6 of connector CON1.

[0006] Preferably, the dual-output MOS unit includes a high-side MOS transistor U2 and a low-side MOS transistor U3; Pin 1 of the high-side MOSFET U2 is electrically connected to the line between the OUT pin of the Hall chip U1 and pin 6 of the connector CON1. ​​Pin 2 of the high-side MOSFET U2 is connected to the VPP power supply node. Pin 3 of the high-side MOSFET U2 is electrically connected to one end of the ferrite bead FB1. The other end of the ferrite bead FB1 is connected to capacitor C5 and pin 3 of the connector CON1 respectively. Capacitor C5 is grounded. Pin 4 of the high-side MOSFET U2 is electrically connected to the line between the VPP power supply node and the VDD pin of U1. Pin 1 of the low-side MOSFET U3 is electrically connected to the OUT pin of the Hall chip U1. Pins 2 and 4 of the low-side MOSFET U3 are connected to one end of the ferrite bead FB2. The other end of the ferrite bead FB2 is electrically connected to pin 4 of connector CON1 and capacitor C6, respectively. Capacitor C6 is grounded, and pin 3 of the low-side MOSFET U3 is grounded.

[0007] Preferably, the reverse conversion circuit includes MOS1 and resistor R2. Pin 1 of MOS1 is electrically connected to one end of resistor R3 and the cathode of Zener diode DZ1. The anode of Zener diode DZ1 is grounded. The other end of resistor R3 is connected between the OUT pin of Hall chip U1 and pin 6 of connector CON1. ​​Pin 3 of MOS1 is connected to the cathode of Zener diode DZ2, one end of resistor R2, and pin 1 of low-side MOS transistor U3. The other end of resistor R2 is connected to the VPP power supply node. Pin 2 of MOS1 is connected to the anode of DZ2 and pin 3 of low-side MOS transistor U3, and is grounded. The line between the OUT pin of Hall chip U1 and pin 6 of connector CON1 is connected to one end of capacitor C4, and the other end of capacitor C4 is grounded.

[0008] Preferably, a resistor R1 is connected between the VPP power supply node and the VDD pin of the Hall chip U1. Pin 4 of the high-side MOSFET U2 is electrically connected between the VPP power supply node and one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C3 and one end of the resistor R5 between the VDD pin of U1 and the other end of the capacitor C3. The other end of the capacitor C3 is connected to the GND pin of U1 and grounded. The other end of the resistor R5 is connected between the resistor R3 and the OUT pin of U1.

[0009] Preferably, it includes capacitors C1 and C2, which are connected in series and electrically connected to pin 1 of connector CON1 and grounded; pin 1 of connector CON1 is connected to the anode of diode D1, the cathode of diode D1 is connected to one end of capacitor C7 and the VPP power supply node, and the other end of C7 is grounded.

[0010] The beneficial effects of the above technical solution are as follows: 1. The Hall chip adopts an integrated on-chip self-test circuit. The chip completes self-tests of Hall sensing elements, amplification units, internal reference voltage based on internal reference source and chip power supply, as well as magnetic field loss within the hardware. Under normal operating conditions, it outputs two complementary braking level signals. In case of fault, a tick pulse fault signal is output from the OUT pin of U1 and output from pin 6 of CON1. ​​No external MCU is required for complex fault judgment. The external MCU directly obtains the position level and the chip's native diagnostic status signal, simplifying the vehicle software logic, improving the chip's fault detection capability, and is compatible with the original vehicle connector interface, replacing the traditional mechanical contact brake switch.

[0011] 2. Two complementary level outputs are achieved through high-side MOSFET U2 and low-side MOSFET U3; FB1-C5 and FB2-C6 form an LC filter circuit to filter out high-frequency noise and meet the BCI anti-interference test requirements; U2 and U3 are intelligent MOSFETs with overvoltage and overcurrent protection capabilities to ensure the reliability of the output circuit.

[0012] 3. Set MOS1, R2, R3, DZ1, and DZ2 to form an inverting conversion circuit to output a mutually exclusive logic signal; DZ1 regulates the voltage of the R3 branch, and DZ2 provides surge protection for MOS1; C4 filters the fault output pin to suppress high-frequency interference.

[0013] 4. R1 and C3 form an RC filter network to filter out high-frequency pulses and protect the power supply of Hall chip U1; R5 serves as a pull-up resistor for the output of U1, ensuring that the chip can output a high-level signal normally and stabilizing the output level of the OUT pin of U1.

[0014] 5. D1 provides reverse polarity protection and can withstand ISO7637 CI pulse impact; C1 and C2 are connected in series to provide electrostatic protection, with a withstand voltage of 100V, and absorb electrostatic interference from the circuit; C7 filters and stabilizes the VPP power supply node to ensure stable power supply for the whole machine. Attached Figure Description

[0015] Figure 1 This is a circuit schematic diagram of an embodiment of the present invention. Detailed Implementation

[0016] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, the present invention provides an automotive braking signal acquisition circuit with a self-diagnostic Hall chip, comprising a Hall chip U1, a dual-output MOS unit, and an inverting conversion circuit. The Hall chip U1 integrates a Hall sensor, an amplifier unit, an internal reference source, and an on-chip self-test circuit. The on-chip self-test circuit performs fault detection within the Hall chip U1 and generates a built-in diagnostic status signal. Specifically, the on-chip self-test circuit can detect open / short circuits in the Hall sensor, detect faults in the amplifier unit, detect internal reference voltage drift, detect undervoltage and overvoltage in the chip's power supply, and detect magnetic field loss. The Hall chip U1 is positioned in the middle of a U-shaped magnet. It uses the change in magnetic field strength caused by the iron block moving closer to and further away from the U-shaped magnet to collect the brake pedal position signal. U1 supports programmable distance configuration to adapt to different pedal structures. The overall static current of this circuit is less than 200μA. The amplifier unit amplifies the magnetic field signal collected by the Hall sensor, and the internal reference source provides a stable reference voltage for the amplifier unit and the on-chip self-test circuit. The Hall chip U1 is used to output two signals, namely a position level signal and a built-in diagnostic status signal; the OUT pin of the Hall chip U1 is electrically connected to pin 6 of connector CON1. The dual-output MOS unit receives the position level signal output by the Hall chip U1, converts it into two complementary level signals, and sends the two complementary level signals to pin 3 and pin 4 of connector CON1, respectively; the inverting conversion circuit is used to output mutual exclusion logic signals. When the external iron block moves away from the Hall sensor position of the U-shaped magnet, pin 3 of connector CON1 outputs a high level, and pin 4 of connector CON1 outputs a low level; when the external iron block moves close to the Hall sensor position of the U-shaped magnet, pin 3 of connector CON1 outputs a low level, and pin 4 of connector CON1 outputs a high level. A 5.1kΩ pull-down resistor can be connected to pin 3 of CON1, and a 1kΩ pull-up resistor up to 14V can be connected to pin 4 of CON1. ​​The values ​​of the pull-down and pull-up resistors can be adjusted according to actual needs. When Hall chip U1 detects an internal fault via its on-chip self-test circuit, its OUT pin outputs a tick pulse fault waveform, which is then output externally via pin 6 of connector CON1. ​​Simultaneously, the vehicle's external MCU acquires the position level signals from CON1-3 and CON1-4, as well as the tick pulse diagnostic signal output from CON1-6. When no fault is detected, the MCU controls the external load to perform corresponding actions based on the position level. Upon receiving a tick pulse fault signal, the MCU reports the fault, which can be displayed on the vehicle's instrument panel. Simultaneously, the external load is shut down. This circuit system meets the ISO26262 ASIL-B functional safety level.

[0018] The dual-output MOS unit includes a smart high-side MOS transistor U2 and a smart low-side MOS transistor U3. U2 and U3 have built-in overvoltage and overcurrent protection functions. Pin 1 of the high-side MOS transistor U2 is electrically connected to the line between the OUT pin of the Hall chip U1 and pin 6 of the connector CON1. ​​Pin 2 of the high-side MOS transistor U2 is connected to the VPP power supply node. Pin 3 of the high-side MOS transistor U2 is electrically connected to one end of the ferrite bead FB1. The other end of the ferrite bead FB1 is connected to capacitor C5 and pin 3 of the connector CON1. ​​Capacitor C5 is grounded. Pin 4 of U2 is electrically connected to the line between the VPP power supply node and the VDD pin of U1; pin 1 of the low-side MOSFET U3 is electrically connected to the OUT pin of the Hall chip U1, pins 2 and 4 of the low-side MOSFET U3 are connected to one end of the ferrite bead FB2, and the other end of the ferrite bead FB2 is electrically connected to pin 4 of connector CON1 and capacitor C6 respectively. Capacitor C6 is grounded, and pin 3 of the low-side MOSFET U3 is grounded; FB1 and C5, and FB2 and C6 respectively form LC filter circuits to filter out high-frequency noise in the line and meet the BCI anti-interference test requirements; The reverse conversion circuit includes MOS1 and resistor R2. Pin 1 of MOS1 is electrically connected to one end of resistor R3 and the cathode of Zener diode DZ1. The anode of Zener diode DZ1 is grounded. R3 and DZ1 form a voltage regulator circuit to protect the gate-source terminal of MOS1. The other end of resistor R3 is connected between the OUT pin of Hall chip U1 and pin 6 of connector CON1. ​​Pin 3 of MOS1 is connected to the cathode of Zener diode DZ2, one end of resistor R2, and pin 1 of low-side MOS transistor U3. The other end of resistor R2 is connected to the VPP power supply node. Pin 2 of MOS1 is connected to the anode of DZ2 and pin 3 of low-side MOS transistor U3, and is grounded. The line between the OUT pin of Hall chip U1 and pin 6 of connector CON1 is connected to one end of capacitor C4, and the other end of capacitor C4 is grounded. A resistor R1 is connected between the VPP power supply node and the VDD pin of the Hall chip U1. Pin 4 of the high-side MOSFET U2 is electrically connected between the VPP power supply node and one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C3 and one end of the resistor R5 between the VDD pin of U1 and the other end of the capacitor C3. The other end of the capacitor C3 is connected to the GND pin of U1 and grounded. R1 and C3 form an RC filter to filter out high-frequency pulses and protect the Hall chip U1. The other end of the resistor R5 is connected between the resistor R3 and the OUT pin of U1. U1 is an open-drain output, and R5 acts as a pull-up resistor to ensure that U1 can output a high level normally. This embodiment also includes capacitors C1 and C2. Capacitors C1 and C2 are connected in series and electrically connected to pin 1 of connector CON1, and grounded. C1 and C2 have a withstand voltage of 100V and are used to absorb static electricity to achieve electrostatic protection. Pin 1 of connector CON1 is connected to the anode of diode D1. The cathode of diode D1 is connected to one end of capacitor C7 and the VPP power supply node, respectively. The other end of C7 is grounded. D1 is a reverse polarity protection diode with a reverse withstand voltage of 250V, which can withstand ISO7637 CI pulse impact.

[0019] This product uses potting compound to isolate it from the external environment, eliminating mechanical wear. Its electronic switch output is reliable and has no mechanical lifespan limitations. It boasts an IP5K3 waterproof rating. The product can be used in brake pedal systems of passenger and commercial vehicles, replacing traditional mechanical contact brake switch signal output solutions.

[0020] The working principle of this circuit is as follows: Hall chip U1 senses the change in magnetic field generated by the coupling of the brake pedal linkage iron block and the U-shaped magnet, and outputs a position level signal. At the same time, the on-chip self-test circuit inside the chip performs fault detection in real time, covering self-tests of Hall sensing element, amplification unit inside the chip, internal reference voltage, chip power supply, and magnetic field loss.

[0021] When the brake pedal is not depressed, the external iron block is away from the magnetic field sensing position, and the Hall chip U1 outputs a corresponding position level signal, which directly drives the dual-output MOS unit, causing pin 3 of connector CON1 to output a high level and pin 4 of connector CON1 to output a low level. When the brake pedal is depressed, the external iron block moves closer to the magnetic field sensing position, and the Hall chip U1 senses the change in magnetic field and flips its level, driving the dual-output MOS unit, causing pin 3 of connector CON1 to output a low level and pin 4 of connector CON1 to output a high level. The inverting conversion circuit synchronously outputs a mutual exclusion logic signal, and the external MCU collects the level signals of pins 3 and 4 of connector CON1 to identify the pedal's working state.

[0022] When the on-chip self-test circuit detects an internal fault in the Hall chip, the OUT pin of Hall chip U1 switches to output a tick pulse fault waveform. This fault waveform is directly transmitted to pin 6 of connector CON1 for external output. After the external MCU recognizes the tick pulse fault signal, it reports the fault, displays the fault information on the vehicle's instrument panel, and shuts off the external load. The peripheral protection filtering circuit works in concert: D1 performs reverse polarity protection, C1 and C2 provide electrostatic discharge protection; R1 and C3 provide RC filtering for the Hall chip power supply; FB1 and C5, and FB2 and C6 form LC filters to filter out high-frequency noise; R3, DZ1, and DZ2 provide voltage regulation and surge protection for MOS1, ensuring stable operation of the circuit in the vehicle's electromagnetic environment.

[0023] This embodiment is merely an example of the technical solution of the present invention and is not intended to limit it. Simple modifications made by those skilled in the art based on the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A vehicle braking signal acquisition circuit with a self-diagnostic Hall effect chip, characterized in that, This includes Hall effect chip U1, dual-output MOS unit, and inverting conversion circuit; The Hall chip U1 integrates a Hall sensor, an amplification unit, an internal reference source, and an on-chip self-test circuit. The on-chip self-test circuit is used to perform fault detection inside the Hall chip U1 and generate a built-in diagnostic status signal. The Hall chip U1 is used to output two signals, namely a position level signal and a built-in diagnostic status signal; the OUT pin of the Hall chip U1 is electrically connected to pin 6 of connector CON1. The dual-output MOS unit is used to receive the position level signal output by the Hall chip U1 and convert it into two complementary level signals. The two complementary level signals are respectively sent to pin 3 and pin 4 of connector CON1. The inverting conversion circuit is used to output a mutual exclusion logic signal; The Hall chip U1 is positioned on a U-shaped magnet. When the external iron block is far from the magnetic field sensing position, pin 3 of connector CON1 outputs a high level, and pin 4 of connector CON1 outputs a low level. When the external iron block is close to the magnetic field sensing position, pin 3 of connector CON1 outputs a low level, and pin 4 of connector CON1 outputs a high level. When the Hall chip U1 detects an internal fault through the on-chip self-test circuit, the OUT pin of the Hall chip U1 outputs a tick pulse fault waveform, which is then output externally through pin 6 of connector CON1.

2. The automotive brake signal acquisition circuit with a self-diagnostic Hall chip according to claim 1, characterized in that: The dual-output MOS unit includes a high-side MOS transistor U2 and a low-side MOS transistor U3; Pin 1 of the high-side MOSFET U2 is electrically connected to the line between the OUT pin of the Hall chip U1 and pin 6 of the connector CON1. ​​Pin 2 of the high-side MOSFET U2 is connected to the VPP power supply node. Pin 3 of the high-side MOSFET U2 is electrically connected to one end of the ferrite bead FB1. The other end of the ferrite bead FB1 is connected to capacitor C5 and pin 3 of the connector CON1 respectively. Capacitor C5 is grounded. Pin 4 of the high-side MOSFET U2 is electrically connected to the line between the VPP power supply node and the VDD pin of U1. Pin 1 of the low-side MOSFET U3 is electrically connected to the OUT pin of the Hall chip U1. Pins 2 and 4 of the low-side MOSFET U3 are connected to one end of the ferrite bead FB2. The other end of the ferrite bead FB2 is electrically connected to pin 4 of connector CON1 and capacitor C6, respectively. Capacitor C6 is grounded, and pin 3 of the low-side MOSFET U3 is grounded.

3. The automotive brake signal acquisition circuit with a self-diagnostic Hall chip according to claim 2, characterized in that: The reverse conversion circuit includes MOS1 and resistor R2. Pin 1 of MOS1 is electrically connected to one end of resistor R3 and the cathode of Zener diode DZ1. The anode of Zener diode DZ1 is grounded. The other end of resistor R3 is connected between the OUT pin of Hall chip U1 and pin 6 of connector CON1. ​​Pin 3 of MOS1 is connected to the cathode of Zener diode DZ2, one end of resistor R2, and pin 1 of low-side MOSFET U3. The other end of resistor R2 is connected to the VPP power supply node. Pin 2 of MOS1 is connected to the anode of DZ2 and pin 3 of low-side MOSFET U3, and is grounded. The line between the OUT pin of Hall chip U1 and pin 6 of connector CON1 is connected to one end of capacitor C4, and the other end of capacitor C4 is grounded.

4. The automotive brake signal acquisition circuit with a self-diagnostic Hall chip according to claim 3, characterized in that: A resistor R1 is connected between the VPP power supply node and the VDD pin of the Hall chip U1. The pin 4 of the high-side MOSFET U2 is electrically connected to the VPP power supply node and one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C3 and one end of the resistor R5 between the VDD pin of U1 and the other end of the capacitor C3. The other end of the capacitor C3 is connected to the GND pin of U1 and grounded. The other end of resistor R5 is connected to the line between resistor R3 and the OUT pin of U1.

5. The automotive brake signal acquisition circuit with a self-diagnostic Hall chip according to any one of claims 1-3, characterized in that: It includes capacitors C1 and C2, which are connected in series and electrically connected to pin 1 of connector CON1 and grounded; pin 1 of connector CON1 is also connected to the anode of diode D1, and the cathode of diode D1 is connected to one end of capacitor C7 and the VPP power supply node, respectively, and the other end of C7 is grounded.

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