Two-wire magnetic switch sensing circuit and chip

Abstract

The application discloses a two-wire magnetic switch sensing circuit and chip, which comprises a linear voltage stabilizer, a tunnel magnetoresistance unit, a comparison unit, a driving unit and a switch unit. The linear voltage stabilizer is used to generate a supply voltage based on a first voltage at a common terminal. The tunnel magnetoresistance unit is connected to the output terminal of the linear voltage stabilizer to generate an induced voltage based on the supply voltage and the change of a magnetic field. The comparison unit is connected to the tunnel magnetoresistance unit and the output terminal of the linear voltage stabilizer, and is used to generate a comparison signal based on the supply voltage and the induced voltage. The driving unit is connected to the output terminal of the comparison unit and the control terminal of the switch unit, and is used to generate a driving signal based on the comparison signal to drive the switch unit. According to the two-wire magnetic switch sensing circuit and chip, there is no spring mechanical contact, and problems such as fatigue, oxidation, glass breakage failure and the like are eliminated. The effective action frequency can reach the level of billions of times, and the circuit is full solid-state and has a long service life, and is suitable for high-frequency and long-term continuous working scenes.

Description

Technical Field

[0001] This invention belongs to the field of magnetic induction sensor integrated circuit technology, specifically relating to a two-wire magnetic switch sensing circuit and chip. Background Technology

[0002] Two-wire magnetic induction switches are widely used in scenarios such as magnetic detection of equipment doors, magnetic detection of flow rate, and position limit. Currently, the mainstream solution for commercial two-wire magnetic switches is a glass-encapsulated reed switch (magnetic reed switch), which relies on the mechanical contact of the internal magnetized reed to achieve on / off switching. This solution has several technical shortcomings that cannot be completely eliminated:

[0003] 1. Fragile packaging and high transportation and assembly costs: Reed switches are vacuum-sealed with glass, making them fragile during transportation, welding, and assembly, requiring additional protective procedures; in addition, they have plug-in pins, which require manual cutting, bending, and welding, resulting in high labor costs and a high breakage and scrap rate.

[0004] 2. Short mechanical lifespan and slow response: Relying on repeated deformation of the reed to achieve on / off switching, long-term operation leads to mechanical fatigue and contact oxidation and adhesion; conventional reed switches have an effective operating frequency of only about 100,000 times, and mechanical deformation causes millisecond-level response delays, making them unsuitable for high-frequency detection scenarios.

[0005] 3. Poor consistency of magnetic field sensitivity: The magnetic action AT value of the reed switch has a large dispersion, and the trigger magnetic field threshold of products in the same batch varies significantly, resulting in a large workload for overall calibration and debugging.

[0006] 4. Power consumption and voltage drop defects: Traditional solid-state two-wire Hall magnetic switches have high on-state voltage drop and large static leakage current, resulting in serious power loss for low-voltage battery-powered equipment.

[0007] Existing solid-state magnetic sensing solutions (AMR / GMR / Hall) cannot simultaneously meet the four major requirements of low voltage drop, low leakage current, high sensitivity, and two-wire compatibility with reed switches. They cannot directly replace reed switches without modifying the circuit board. The industry urgently needs a two-wire magnetic switch chip that is all-solid-state, low-power, and directly compatible with existing circuits.

[0008] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide a two-wire magnetic switch sensing circuit and chip that can achieve a fully solid-state design without mechanical contacts, while taking into account ultra-low on-state voltage drop, microampere-level leakage current, high-frequency fast response, and current load support capability. The electrical logic is fully compatible with reed switches, and it can directly replace traditional reed switches to achieve a fully solid-state design without mechanical contacts without modifying the interface.

[0010] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: a two-wire magnetic switch sensing circuit, comprising: a linear regulator, a tunnel magnetoresistive unit, a comparator unit, a drive unit, and a switch unit;

[0011] The input terminal of the linear regulator is connected to a common terminal, which is connected to the power supply voltage through an intermediate module. The linear regulator is used to generate a power supply voltage based on a first voltage at the common terminal.

[0012] The tunnel magnetoresistive unit is connected to the output of the linear regulator to generate an induced voltage based on changes in the supply voltage and magnetic field.

[0013] The comparison unit is connected to the output of the tunnel magnetoresistive unit and the linear regulator, and the comparison unit is used to generate a comparison signal based on the supply voltage and the induced voltage.

[0014] The driving unit is connected to the output terminal of the comparator unit and the control terminal of the switching unit. The first terminal of the switching unit is connected to the reference voltage, and the second terminal of the switching unit is connected to the common terminal. The driving unit is used to generate a driving signal based on the comparison signal to drive the switching unit.

[0015] In one or more embodiments of the present invention, the tunnel magnetoresistive unit includes a first magnetoresistive element and a second magnetoresistive element. A first end of the first magnetoresistive element is used to receive a power supply voltage. A second end of the first magnetoresistive element and a first end of the second magnetoresistive element are connected to a comparison unit to generate an induced voltage. A second end of the second magnetoresistive element is connected to a reference voltage.

[0016] In one or more embodiments of the present invention, the comparison unit includes a voltage divider network and a comparator. The voltage divider network is connected to the output of a linear regulator to generate a reference voltage based on the supply voltage. The first input of the comparator is connected to a tunnel magnetoresistive unit to receive an induced voltage. The second input of the comparator is connected to the voltage divider network to receive the reference voltage. The output of the comparator is used to output a comparison signal.

[0017] In one or more embodiments of the present invention, the two-wire magnetic switch sensing circuit further includes an adjustment module connected to a voltage divider network to adjust the reference voltage.

[0018] In one or more embodiments of the present invention, the two-wire magnetic switch sensing circuit further includes a resistor unit and an overcurrent protection circuit. The first end of the resistor unit is connected to the first end of the switch unit, the second end of the resistor unit is connected to a reference voltage, the input end of the overcurrent protection circuit is connected to the first end of the resistor unit, and the output end of the overcurrent protection circuit is connected to the input end of the drive unit.

[0019] In one or more embodiments of the present invention, the switching unit includes a switching transistor, the control terminal of the switching transistor is connected to the output terminal of the driving unit, the first terminal of the switching transistor is connected to a reference voltage, and the second terminal of the switching transistor is connected to a common terminal.

[0020] In one or more embodiments of the present invention, the switching unit further includes a clamping unit, and the second end of the switching transistor is connected to a common terminal through the clamping unit.

[0021] In one or more embodiments of the present invention, the clamping unit includes one or more diodes connected in series.

[0022] In one or more embodiments of the present invention, the two-wire magnetic switch sensing circuit further includes a Schmitt trigger unit, wherein the input terminal of the Schmitt trigger unit is connected to the output terminal of the comparator unit, and the output terminal of the Schmitt trigger unit is connected to the input terminal of the drive unit.

[0023] The present invention discloses a chip including the two-wire magnetic switch sensing circuit described above. The chip has a first pin and a second pin, the first pin being connected to a common terminal and the second pin being connected to a reference voltage.

[0024] Compared with existing technologies, the two-wire magnetic switch sensing circuit and chip of this invention eliminates the need for reed mechanical contacts, thus avoiding problems such as fatigue, oxidation, and glass breakage failure. It boasts an effective operating cycle count of up to hundreds of millions of times, a long lifespan due to its all-solid-state design, and suitability for high-frequency, long-term continuous operation. With a conduction voltage drop of <1.2V, a shutdown leakage current of <20μA, and a static power consumption of <5μA, it exhibits ultra-low electrical losses, making it suitable for battery-powered low-power devices. The two-wire pin definition, magnetic field on / off logic, IO levels, and current load capacity match those of traditional reed switches, ensuring seamless compatibility and replacement. Existing devices can be directly replaced without board modifications or debugging. This reduces the overall upgrade cost; the high magnetoresistive change rate of the tunnel magnetoresistive unit can detect weak magnetic fields; Schmitt molding suppresses power supply and electromagnetic interference, providing high sensitivity and anti-interference, and eliminating jitter during switching; SMT surface mount packaging enables automated placement, eliminating manual lead cutting and bending processes, preventing glass breakage and scrap, reducing device size, and adapting to miniaturized intelligent devices, offering advantages in assembly and mass production; a wide voltage input of 1.2V~5.5V, a current load capacity of 200mA, and an externally adjustable magnetic threshold provide wide adaptability, supporting various magnetic detection scenarios such as industrial, home appliance, and portable electronics. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a circuit diagram of a two-wire magnetic switch sensing circuit according to an embodiment of the present invention.

[0027] Figure 2 This is a circuit diagram of a tunnel magnetoresistive unit in one embodiment of the present invention.

[0028] Figure 3 This is a circuit diagram of the comparison unit in one embodiment of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0030] The terms "coupled," "connected," or "linked" in the specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrical conduction medium, which may have parasitic inductance or capacitance. Indirect connections may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections through switches, follower circuits, or other circuits or components. Furthermore, in the invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship, quantity, or order between these technical features.

[0031] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this disclosure. Therefore, the following detailed description should not be considered limiting.

[0032] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0033] For the purposes of this disclosure, the phrase “A and / or B” means (A), (B), or (A and B). For the purposes of this disclosure, the phrase “A, B and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0034] Various components and devices may be referred to or shown in the singular (e.g., “transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0035] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used with respect to embodiments of this disclosure are synonymous.

[0036] like Figure 1 As shown, a two-wire magnetic switch sensing circuit according to an embodiment of the present invention includes: a linear regulator LILO, a tunnel magnetoresistive unit TMR, a comparator unit CMOP, a Schmitt trigger unit SCC, a driver unit, a switch unit, a resistor unit Rc, and an overcurrent protection circuit OCP.

[0037] The input terminal of the linear regulator LILO is connected to the common terminal G. The common terminal G is connected to the power supply voltage Vcc through an intermediate module (not shown in the figure). The linear regulator LILO is used to generate the supply voltage VL based on the first voltage at the common terminal G. The common terminal G also constitutes the output terminal Vout of the two-wire magnetic switch sensing circuit.

[0038] In one embodiment, the linear regulator LILO has an input voltage range of 1.2V to 5.5V and a stable output of 1V as its internal power supply voltage, with a static current consumption of <5μA. The linear regulator LILO adopts an NMOS transmission transistor topology, which has little impact on the stability of the output capacitor loop, strong compatibility, and is compatible with ceramic capacitors of 10μF and above. Its low-voltage input transient response performance is better than that of traditional PMOS linear regulators, thus providing stable and low-noise power supply for the tunnel magnetoresistive unit (TMR), comparator unit (CMOP), Schmitt trigger unit (SCC), and driver unit.

[0039] The tunnel magnetoresistive unit (TMR) is connected to the output of the linear regulator (LILO) to generate an induced voltage (VO) based on the changes in the supply voltage (VL) and the magnetic field (B).

[0040] The comparator unit CMOP is connected to the output of the tunnel magnetoresistive unit TMR and the linear regulator LILO. The comparator unit CMOP is used to generate a comparison signal based on the supply voltage VL and the induced voltage VO.

[0041] The input terminal of the Schmitt trigger unit (SCC) is connected to the output terminal of the comparator unit (CMOP). The output terminal of the Schmitt trigger unit (SCC) is connected to the first input terminal of the driver unit (Driver). The output terminal of the driver unit (Driver) is connected to the control terminal of the switching unit. The driver unit (Driver) is used to generate a drive signal based on the signal output by the Schmitt trigger unit (SCC) to drive the switching unit.

[0042] In one embodiment, the Schmitt trigger unit (SCC) is composed of a voltage comparator; the Schmitt trigger unit (SCC) is used to shape the comparison signal, eliminate signal jitter, and ensure the stability of subsequent switching operations by stabilizing the transmission link from the comparison signal to the drive signal.

[0043] like Figure 2 As shown, the tunnel magnetoresistive unit (TMR) includes a first magnetoresistive element (TMR1) and a second magnetoresistive element (TMR2). The first terminal of the first magnetoresistive element (TMR1) receives the supply voltage VL. The second terminal of the first magnetoresistive element (TMR1) and the first terminal of the second magnetoresistive element (TMR2) are connected to a comparator unit (CMOP) to generate an induced voltage VO. The second terminal of the second magnetoresistive element (TMR2) is connected to a reference voltage. In one embodiment, the reference voltage is ground voltage GND.

[0044] The first magnetoresistive element TMR1 and the second magnetoresistive element TMR2 form a half-bridge sensing circuit as the magnetic sensing core. When there is no external magnetic field B, the resistance of the first magnetoresistive element TMR1 is equal to the resistance of the second magnetoresistive element TMR2, and the half-bridge output voltage is equal to VL / 2. When an effective magnetic field B is applied, the resistance of the first magnetoresistive element TMR1 decreases, and the resistance of the second magnetoresistive element TMR2 increases, causing the half-bridge output voltage to shift and become greater than VL / 2, forming a recognizable magnetic induction differential signal. Compared with Hall, AMR, and GMR magnetic sensing schemes, the tunnel magnetoresistive unit (TMR) has a higher magnetoresistive change rate, can detect weak magnetic fields, and has higher magnetic field sensitivity. Simultaneously, its high resistance characteristic significantly reduces turn-off leakage current, achieving low voltage drop, ultra-low power consumption, and microsecond-level high-frequency response. The magnetic sensing axis supports single-axis, X / Y, X / Z, and other multi-axis magnetic field detection.

[0045] In other embodiments, the tunnel magnetoresistive unit (TMR) can be a balanced Wheatstone full-bridge structure to further enhance the common-mode interference rejection capability. The two differential signals output from the full-bridge are respectively connected to one input terminal of the two comparator units (CMOP). Through differential comparison, the driver unit generates a drive signal, resulting in stronger common-mode rejection capability, which is suitable for industrial environments with strong electromagnetic interference.

[0046] In one embodiment, a capacitor is connected between the first terminal of the first magnetoresistive element TMR1 and the reference voltage to suppress high-frequency power supply interference, avoid distortion of weak magnetic signals, and improve the sampling stability of weak magnetic signals.

[0047] like Figure 3 As shown, the comparator unit CMOP includes a voltage divider network and a comparator U1. The voltage divider network is connected to the output of the linear regulator LILO to generate a reference voltage based on the supply voltage. The first input of comparator U1 is connected to the tunnel magnetoresistive unit TMR to receive the induced voltage VO. The second input of comparator U1 is connected to the voltage divider network to receive the reference voltage. The output of comparator U1 is used to output a comparison signal, which is transmitted to the input of the Schmitt trigger unit SCC through a third resistor R3. A filter capacitor Cc is connected between the first and second inputs of comparator U1. A filter capacitor (not shown) is also connected to the power supply terminal of comparator U1 to filter out high-frequency noise from the power supply and prevent weak magnetic signals from being distorted by interference. In one embodiment, the first input of comparator U1 is a non-inverting input, and the second input of comparator U1 is an inverting input.

[0048] The voltage divider network includes a first resistor R2 and a second resistor R3. The first terminal of the first resistor R1 is connected to the output of the linear regulator LILO. The second terminal of the first resistor R1 is connected to the first terminal of the second resistor R2 and the second input of the comparator U1 to form a connection node, generating a reference voltage based on the voltage division of the supply voltage. The second terminal of the second resistor R2 is connected to the reference voltage. The two-wire magnetic switch sensing circuit also includes an adjustment module, which is connected to the connection node of the voltage divider network to adjust the reference voltage.

[0049] like Figure 1 As shown, the switching unit includes a switching transistor M and a clamping unit. The control terminal of the switching transistor is connected to the output terminal of the driving unit Driver, and the second terminal of the switching transistor is connected to the common terminal G through the clamping unit. The clamping unit includes a diode D. The anode of the diode D is connected to the common terminal G, and the cathode of the diode D is connected to the second terminal of the switching transistor M. In one embodiment, the switching transistor M is an N-channel MOSFET, the control terminal of the switching transistor is the gate, the first terminal of the switching transistor is the source, and the second terminal of the switching transistor is the drain.

[0050] In other embodiments, the number of diodes D can be set as needed, with multiple diodes D connected in series. Diodes D can raise and stabilize the voltage at the common terminal G, thus stabilizing the input voltage range of the linear regulator LILO and preventing the LILO from malfunctioning due to excessively low voltage at the common terminal G.

[0051] The switching transistor M serves as the output switching transistor, forming a two-wire series output structure. In the absence of a magnetic field: the switching transistor M is turned off, and there is almost no current between the two wires, with a leakage current of <20μA. In the presence of an effective magnetic field: the switching transistor M is turned on, and the two wires are clamped by low resistance, with a forward voltage drop of <1.2V. At the same time, the path containing the switching transistor M can withstand a current of at least 200mA. When the external power supply is ≥3.3V, the standard forward voltage drop is stable at 1.2V.

[0052] like Figure 1 As shown, the first terminal of resistor Rc is connected to the first terminal of the switching transistor M in the switching unit, and the second terminal of resistor Rc is connected to a reference voltage. The input terminal of the overcurrent protection circuit OCP is connected to the first terminal of resistor Rc, and the output terminal of the overcurrent protection circuit OCP is connected to the second input terminal of the drive unit Driver. The overcurrent protection circuit OCP determines whether a short circuit has occurred by detecting the voltage across resistor Rc, and the drive unit Driver adjusts the state of the switching transistor M in real time based on the protection feedback. In one embodiment, a short circuit can be considered to have occurred when the current across resistor Rc exceeds 250mA, and the switching transistor M is automatically turned off when the load is short-circuited to prevent the circuit chip from burning out.

[0053] This invention also discloses a chip including the aforementioned two-wire magnetic switch sensing circuit. The chip has a first pin and a second pin. The first pin is connected to a common terminal G, and the second pin is connected to a reference voltage. The chip also has a reserved adjustment pin Adj. An adjustment module is connected to the adjustment pin Adj. The adjustment module is used to generate an adjustment voltage to adjust the reference voltage, thereby adjusting the action threshold of the two-wire magnetic switch sensing circuit inside the chip. In one embodiment, the adjustment module can be an adjustable resistor, thereby changing the voltage division of the voltage divider network, thus linearly adjusting the internal magnetic action threshold of the chip to adapt to application scenarios with different magnetic field strengths.

[0054] The switching transistor M is controlled by the signal output from the driver unit. The second terminal of transistor M is connected to the positive terminal of the external power supply, and the first terminal is connected to the negative terminal. When transistor M is off, there is no current in the upper and lower paths, and the voltage difference between the first and second pins of the chip is approximately equal to the external power supply voltage. When transistor M is on, the path is open, and the first pin is clamped to a low voltage; this clamping voltage is the chip's on-state voltage drop. The chip only has two power supply pins exposed. The chip's on-state voltage drop is less than 1.2V, and the turn-off leakage current is less than 20μA. Under external power supply voltage ≥ 3.3V, the chip's on-state voltage drop is controlled to be 1.2V.

[0055] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0056] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and 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.

Claims

1. A two-wire magnetic switch sensing circuit, characterized in that, include: Linear regulator, tunnel magnetoresistive unit, comparator unit, drive unit, and switching unit; The input terminal of the linear regulator is connected to a common terminal, which is connected to the power supply voltage through an intermediate module. The linear regulator is used to generate a power supply voltage based on a first voltage at the common terminal. The tunnel magnetoresistive unit is connected to the output of the linear regulator to generate an induced voltage based on changes in the supply voltage and magnetic field. The comparison unit is connected to the output of the tunnel magnetoresistive unit and the linear regulator, and the comparison unit is used to generate a comparison signal based on the supply voltage and the induced voltage. The driving unit is connected to the output terminal of the comparator unit and the control terminal of the switching unit. The first terminal of the switching unit is connected to the reference voltage, and the second terminal of the switching unit is connected to the common terminal. The driving unit is used to generate a driving signal based on the comparison signal to drive the switching unit.

2. The two-wire magnetic switch sensing circuit according to claim 1, characterized in that, The tunnel magnetoresistive unit includes a first magnetoresistive element and a second magnetoresistive element. The first end of the first magnetoresistive element is used to receive the power supply voltage. The second end of the first magnetoresistive element and the first end of the second magnetoresistive element are connected to a comparison unit to generate an induced voltage. The second end of the second magnetoresistive element is connected to a reference voltage.

3. The two-wire magnetic switch sensing circuit according to claim 1, characterized in that, The comparison unit includes a voltage divider network and a comparator. The voltage divider network is connected to the output of a linear regulator to generate a reference voltage based on the supply voltage. The first input of the comparator is connected to a tunnel magnetoresistive unit to receive the induced voltage. The second input of the comparator is connected to the voltage divider network to receive the reference voltage. The output of the comparator is used to output a comparison signal.

4. The two-wire magnetic switch sensing circuit according to claim 3, characterized in that, The two-wire magnetic switch sensing circuit also includes an adjustment module, which is connected to a voltage divider network to adjust the reference voltage.

5. The two-wire magnetic switch sensing circuit according to claim 1, characterized in that, The two-wire magnetic switch sensing circuit also includes a resistor unit and an overcurrent protection circuit. The first end of the resistor unit is connected to the first end of the switch unit, the second end of the resistor unit is connected to the reference voltage, the input end of the overcurrent protection circuit is connected to the first end of the resistor unit, and the output end of the overcurrent protection circuit is connected to the input end of the drive unit.

6. The two-wire magnetic switch sensing circuit according to claim 1, characterized in that, The switching unit includes a switching transistor. The control terminal of the switching transistor is connected to the output terminal of the driving unit. The first terminal of the switching transistor is connected to a reference voltage, and the second terminal of the switching transistor is connected to a common terminal.

7. The two-wire magnetic switch sensing circuit according to claim 6, characterized in that, The switching unit also includes a clamping unit, and the second end of the switching transistor is connected to the common terminal through the clamping unit.

8. The two-wire magnetic switch sensing circuit according to claim 7, characterized in that, The clamping unit includes one or more diodes connected in series.

9. The two-wire magnetic switch sensing circuit according to claim 1, characterized in that, The two-wire magnetic switch sensing circuit also includes a Schmitt trigger unit, the input of which is connected to the output of the comparator unit, and the output of which is connected to the input of the drive unit.

10. A chip, characterized in that, The chip includes a two-wire magnetic switch sensing circuit as described in any one of claims 1 to 9, wherein the chip has a first pin and a second pin, the first pin being connected to a common terminal and the second pin being connected to a reference voltage.

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