Magnetic latching switch based on LTCC (Low Temperature Co-Fired Ceramic) integration and preparation method thereof
The magnetic latching switch, which combines the LTCC three-dimensional stacking process and the magnetoresistive unit, uses pulse current to change the resistance state of the magnetoresistive unit, solving the problem of false tripping of traditional magnetic latching relays under mechanical vibration and impact, and achieving fast response and low-power switching, making it suitable for high-reliability scenarios such as aerospace.
Patent Information
- Application Number
- CN202510764303.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-09-19
AI Technical Summary
Traditional magnetic latching relays are prone to false tripping under mechanical vibration and shock, and have slow response speeds, which increases manufacturing costs and makes it difficult to completely avoid misoperation.
The LTCC three-dimensional stacking process is combined with the magnetoresistive unit. The magnetic field is generated by pulse current to change the resistance state of the magnetoresistive unit. The comparator switching circuit is used to achieve switching to avoid mechanical movement.
It achieves miniaturization, fast response and shock resistance, reduces power consumption, avoids false trips caused by mechanical movement, and is suitable for high-reliability scenarios such as aerospace.
Smart Images
Figure CN120675548A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electronic devices and their manufacture, and in particular relates to a magnetic latching switch based on LTCC integration and a preparation method thereof. Background Art
[0002] The magnetic latching relay is a widely used automatic switch, operating primarily based on electromagnetic induction and magnetic field retention. It maintains its normally closed or normally open state through the action of a permanent magnet, while switching between on and off states is triggered by a pulsed electrical signal. A key feature of this relay is that it requires no continuous power to maintain its state; a pulse signal is only applied when the state needs to change, resulting in energy savings and efficient control. Its advantages include low power consumption, environmental protection, and the ability to withstand high current loads, making it a key component in fields such as automated control and power systems. Magnetic latching relays are also widely used in the aerospace industry to achieve on-off switching.
[0003] The main structure of the magnetic latching relay consists of two parts, namely the electromagnetic system and the contact circuit (the structure is shown in the figure below). Figure 1 (as shown). The electromagnetic system consists of a magnet, armature, core, and coil, while the contact circuit comprises a spring, reed, stator, and contacts. Due to the presence of a permanent magnet, a latching relay can remain in either the open or closed state for extended periods without consuming any power. To switch states, a pulsed current in a specific direction is simply fed into the coil, changing the direction of the magnetic field of the armature assembly composed of the magnet and pole piece. The armature assembly then controls the opening and closing of the contact circuit via a push rod. However, conventional latching relays use the mechanical movement of the armature to switch on and off. When subjected to significant mechanical vibration, shock, or acceleration, the armature may break free from the magnet's attachment, causing a false trip and a switching error. To address this issue, numerous protective measures must be implemented to mitigate the effects of external shocks. This not only significantly increases manufacturing costs but also makes it difficult to completely prevent misoperation. Furthermore, conventional latching relays, which rely on the mechanical movement of the armature to switch on and off, also suffer from slow response speeds.
[0004] Therefore, if a magnetic latching induction switch module can be developed that does not rely on the mechanical movement of the armature to achieve switching, and can also take into account comprehensive technical requirements such as low power consumption and small size, then it will be of great significance and value in application fields such as aerospace that have high requirements for the impact resistance, reliability and environmental adaptability of magnetic latching induction switches. Summary of the Invention
[0005] To address the aforementioned problems and shortcomings, and to address the instability of existing magnetic latching switches due to their reliance on mechanical armature motion to switch, resulting in insufficient stability when subjected to external forces, the present invention provides a magnetic latching switch based on LTCC (low-temperature co-fired ceramic) integration and a method for its fabrication. This invention combines the LTCC three-dimensional stacking process with the magnetoresistive element (Giant Magnetoresistance (GMR) or Tunnel Magnetoresistance (TMR)) effect, resulting in a novel, compact, integrated magnetic latching switch with fast response and shock resistance.
[0006] A magnetic latching switch based on LTCC integration includes an LTCC electromagnet and a magnetoresistive unit.
[0007] The LTCC electromagnet is provided with a cavity for accommodating a magnetoresistive unit. When a pulse current is passed through the winding coil of the LTCC electromagnet winding, a magnetic field H generated in the cavity causes the magnetoresistive unit placed in the cavity to undergo magnetic reversal.
[0008] There are four magnetoresistive units, corresponding to R1 to R4 respectively, and the magnetoresistive units R1 to R4 form a Wheatstone bridge.
[0009] When forming a Wheatstone bridge: the four magnetoresistive units R1 to R4 are placed with the pinning fields of R1 and R3 parallel to the +y direction, and the pinning fields of R2 and R4 parallel to the -y direction; the entire Wheatstone bridge structure is a 4-port device, A is the current input terminal, B is the current output terminal, and C and D are voltage detection terminals.
[0010] A detection current flows between terminals A and B, and a comparator switch circuit is connected to terminals C and D. The detection current is provided by the steady-state operating current of the comparator switch circuit. The comparator switch circuit compares the voltage levels at terminals C and D. When the voltage level at terminal C is higher than that at terminal D, the comparator outputs a high voltage, turning on the connected MOS switch transistor and thus the operating circuit. When the voltage level at terminal C is lower than that at terminal D, the comparator outputs a low voltage, turning off the connected MOS switch transistor and thus the operating circuit.
[0011] Assuming the magnetic field applied to the latching switch is in the +y direction when switching on and in the -y direction when switching off, when the LTCC electromagnet is excited by a forward pulse current (applying a +y-direction pulsed magnetic field), R1 and R3 are small resistors, R2 and R4 are large resistors, the voltage at point C is higher than that at point D, and the output voltage at the C and D terminals of the Wheatstone bridge is positive, turning the entire latching switch on. Conversely, when the LTCC electromagnet is excited by a reverse pulse current (applying a -y-direction pulsed magnetic field), R1 and R3 are large resistors, R2 and R4 are small resistors, the voltage at point C is lower than that at point D, and the output voltage at the C and D terminals of the Wheatstone bridge is negative, turning the entire latching switch off. Thus, the present invention replaces the armature switch in the prior art by using a comparator switch circuit.
[0012] Furthermore, the winding of the LTCC electromagnet is a combination of a planar winding and a three-dimensional stacked structure, so as to achieve a large magnetic field H in a minimum overall volume, which is beneficial to the miniaturization of the overall device.
[0013] Furthermore, the comparator switch circuit is integrated on the outer surface of the LTCC electromagnet, further reducing the volume of the entire circuit system and achieving integrated integration.
[0014] Furthermore, the magnetoresistive unit is a GMR magnetoresistive unit or a TMR magnetoresistive unit. The GMR magnetoresistive unit may adopt a conventional switch-type giant magnetoresistive structure, and the TMR magnetoresistive unit may adopt a conventional tunnel magnetoresistive structure.
[0015] Furthermore, the LTCC electromagnet adopts a double-winding structure or a single-winding structure.
[0016] When the LTCC electromagnet adopts a single-winding structure (as shown in the embodiment), the overall size is smaller; however, a forward pulse current and a reverse pulse current need to be input separately to realize the switching, so the control circuit will be more complicated.
[0017] If a dual-winding structure is used, with current pulses flowing through both windings in the same direction, one generates a magnetic field in the +y direction and the other generates a magnetic field in the -y direction, simplifying the control circuit. To turn the switch on, a current pulse is applied to the winding generating the +y magnetic field; to turn the switch off, a current pulse is applied to the winding generating the -y magnetic field. However, a dual-winding structure requires the processing of two windings, which increases the size of the LTCC electromagnet. For reasons of miniaturization, a single-winding structure is preferred.
[0018] Furthermore, an adapter plate is added to the cavity of the LTCC electromagnet for transition. The Wheatstone bridge is first bonded to the adapter plate, and then the adapter plate is placed in the cavity of the LTCC electromagnet. The four wires of the four ports A, B, C, and D of the Wheatstone bridge are led out to the outside of the LTCC electromagnet through the adapter plate to facilitate connection with the external electrode.
[0019] Furthermore, the adapter board adopts a PCB board, LTCC or HTCC substrate.
[0020] Furthermore, the LTCC ceramic of the LTCC electromagnet is made of non-magnetic dielectric ceramic or ferrite ceramic. Ferrite ceramic produces a lower magnetic field, hindering miniaturization. Non-magnetic dielectric ceramic can generate a larger magnetic field within the cavity at the same size and current. The LTCC electromagnet windings utilize screen-printed electronic paste, such as silver paste.
[0021] The preparation method of the LTCC-based integrated magnetic latching switch comprises the following specific steps:
[0022] Step 1: Based on the LTCC three-dimensional stacking technology, according to the magnitude of the magnetic field H required for the flipping of the selected magnetoresistive unit, design and process an LTCC electromagnet whose magnitude of the magnetic field H generated in the cavity matches the selected magnetoresistive unit.
[0023] Step 2: Prepare a Wheatstone bridge corresponding to the selected magnetoresistive unit.
[0024] Step 3: Place the Wheatstone bridge prepared in Step 2 inside the cavity of the LTCC electromagnet prepared in Step 1, and extend the four leads corresponding to the four ports A, B, C, and D of the Wheatstone bridge to the outside of the LTCC electromagnet. If an adapter plate is used, first secure the Wheatstone bridge to the transition adapter plate before placing it in the cavity. Then, extend the four leads corresponding to the four ports A, B, C, and D through the adapter plate.
[0025] Step 4: For the four leads of the Wheatstone bridge, A, B, C, and D, a detection current flows between A and B, and a comparator switch circuit is connected to terminals C and D. The comparator switch circuit: When the voltage level at terminal C is higher than that at terminal D, the comparator switch turns on, connecting the comparator switch circuit's operating circuit to the load. When the voltage level at terminal C is lower than that at terminal D, the comparator switch turns off, disconnecting the comparator switch circuit's operating circuit from the load.
[0026] The above-mentioned LTCC-based integrated magnetic latching switch is used:
[0027] A forward current pulse with a pulse duration of 0.5 to 10 ms is passed through the LTCC electromagnet, so that the magnetic field provided by the LTCC electromagnet is along the +y direction, R1 and R3 are in a low resistance state, and R2 and R4 are in a high resistance state; at this time, since a 1 to 20 mA detection current is applied to the A and B terminals, the comparator detects that the voltage level at the C terminal is higher than the voltage level at the D terminal, the external comparator switch is turned on, and the working circuit of the comparator switch circuit is connected to the load.
[0028] When switching is required, a reverse current pulse with a pulse duration of 0.5 to 10 ms is passed through the LTCC electromagnet, which instantly generates a magnetic field in the -y direction in the electromagnet, causing the states of the four magnetoresistive units to change. R1 and R3 change from their original low resistance state to a high resistance state, and R2 and R4 change from their original high resistance state to a low resistance state. At this time, due to the detection current applied to the A and B terminals, the comparator detects that the voltage level at the C terminal is lower than the voltage level at the D terminal, triggering the external comparator switch circuit to change from on to off, and the working circuit of the comparator switch circuit is not conducting.
[0029] If the switch is switched again, a forward current pulse with a pulse duration of 0.5 to 10 ms is passed to the LTCC electromagnet.
[0030] The size of the current pulse applied by the LTCC electromagnet depends on the specific number of winding turns and the size of the reversal field of the magnetoresistive unit (GMR or TMR). That is, it is necessary to ensure that the magnetic field H generated in the LTCC electromagnet cavity is sufficient to cause the magnetic moment of the placed magnetoresistive unit (GMR or TMR) to reverse, so that the resistor can switch between high and low resistance states.
[0031] The main advantages of the magnetic latching switch module provided by the present invention are:
[0032] 1. Small size and easy integration: The use of LTCC three-dimensional stacking technology to realize the electromagnet circuit can greatly reduce the overall size and maintain the consistency of product performance. In addition, the comparator switch circuit can also be integrated on the surface of the LTCC electromagnet, further reducing the volume of the overall circuit system and achieving integrated integration.
[0033] 2. Fast response speed: The magnetic latching switch state switching only requires applying positive and reverse current pulses to the LTCC electromagnet to flip the magnetic resistance state of the magnetoresistive unit (GMR or TMR), thereby triggering the on and off switching of the comparator switch circuit; compared with the traditional magnetic latching relay switch switching method through the mechanical movement of the armature, the response speed is improved by 1 to 2 orders of magnitude.
[0034] 3. Resistance to mechanical shock: Since the magnetic latching switch of the present invention generates a magnetic field through a pulse current, and then changes the resistance value of the magnetoresistive unit (GMR or TMR) through the magnetic field, thereby triggering the switching mode of the comparator switch circuit from on to off to achieve the switching of the switch, the whole process does not involve any mechanical movement, avoiding the problem of unstable magnetic adsorption of the armature used in traditional magnetic latching relays under impact or acceleration, resulting in false switching, and completely solving the "pain points" of traditional magnetic latching relay switches.
[0035] 4. Low power consumption and non-volatility: This magnetic latching switch does not normally require power to the LTCC electromagnet. Only when switching is required is a forward or reverse current pulse of only 0.5 to 10ms applied to the LTCC electromagnet. The magnetic resistance state of the magnetoresistive element (GMR or TMR) is flipped and permanently maintained, making it non-volatile. Even if the system experiences a power outage during use, the state of the switch before the power outage can still be accurately determined. This also triggers the subsequent comparator switch circuit to connect or disconnect. Therefore, the switching power consumption is extremely low, which has the advantages of low power consumption and non-volatility.
[0036] In summary, the LTCC-based integrated magnetic latching switch provided by the present invention not only has outstanding advantages such as small size and fast response speed, but also does not have the problem of poor impact resistance of traditional magnetic latching relay switches, and has extremely high reliability. It is particularly suitable for aerospace and other magnetic latching switch application scenarios with high requirements for reliability and integration, and has very important value. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 This is the model and physical picture of the traditional magnetic latching relay.
[0038] Figure 2 This is a diagram of the LTCC electromagnet model of the embodiment.
[0039] Figure 3 The Wheatstone bridge structure connection diagram of the TMR magnetoresistive unit and the GMR magnetoresistive unit.
[0040] Figure 4 Assembly diagram of the LTCC-based integrated magnetic latching switch in the embodiment. DETAILED DESCRIPTION
[0041] The present invention will be further described in detail below with reference to embodiments and accompanying drawings.
[0042] A method for preparing a magnetic latching switch based on LTCC integration, the specific steps are as follows:
[0043] Step 1: Complete the production of LTCC electromagnet based on LTCC three-dimensional lamination technology:
[0044] In this embodiment, the external magnetic field H required for the GMR magnetoresistive unit to flip its magnetic moment (causing the resistance to switch between high and low) is 70Oe; according to this requirement, we actually Figure 2 The LTCC electromagnet, designed using a structure combining planar windings and three-dimensional stacking, consists of 36 layers, 30 of which are internally wound. The overall structure is a hollow cylinder, with the hollow portion housing the GMR magnetoresistive element. When a 250mA pulse current is applied to the windings, a minimum magnetic field exceeding 75Oe is generated within the cavity. The LTCC electromagnet measures 9×8×3.2mm, with the internal cavity measuring 3×2.5mm, resulting in a very compact overall structure.
[0045] The lead-in and lead-out ends of the LTCC electromagnet winding coil are moved to the upper surface of the LTCC module, such as Figure 4 As shown, they are marked with IN and OUT electrodes respectively to facilitate external circuit connection.
[0046] Step 2: Prepare the Wheatstone bridge corresponding to the selected magnetoresistive unit:
[0047] This embodiment uses GMR magnetoresistive units to construct a Wheatstone bridge structure, such as Figure 3 (b) Four GMR magnetoresistive units are interconnected. The resistance change rate between the high-resistance and low-resistance states of each GMR magnetoresistive unit is 8%, and the switching magnetic field that causes the resistance change is 70Oe. The four GMR magnetoresistive units R1 through R4 are all manufactured using the same process. R1 and R3 are made on one silicon substrate, and R2 and R4 are made on another. The substrate used to make R2 and R4 is then rotated 180 degrees, achieving the opposite effect of the resistance changes of R1 and R3 compared to R2 and R4.
[0048] Working principle and effect of GMR (or TMR) magnetoresistive unit:
[0049] When a magnetic field is applied that is greater than the coercive field of ferromagnetic layer 1 (free layer) and antiparallel to the pinning field of the ferromagnetic layer 2 / antiferromagnetic pinning structure, the magnetoresistive cell exhibits a high resistance state. This resistance value is maintained even after the external magnetic field is removed, demonstrating non-volatility. When a magnetic field is applied that is greater than the coercive field of ferromagnetic layer 1 (free layer) and parallel to the pinning field of the ferromagnetic layer 2 / antiferromagnetic pinning structure, the cell exhibits a low resistance state. This resistance value is also maintained even after the external magnetic field is removed. In other words, a GMR (or TMR) magnetoresistive cell has two non-volatile resistance states: a high resistance state and a low resistance state.
[0050] The difference between the high and low resistance values of a GMR magnetoresistive cell is approximately 5% to 15%, while the difference between the high and low resistance values of a TMR cell can reach 50% to 200%. However, the TMR magnetoresistive cell fabrication process is more demanding and has lower process consistency than the GMR magnetoresistive cell. Furthermore, since the resistance value of a GMR (TMR) magnetoresistive cell is affected by temperature drift, a Wheatstone bridge circuit is used to offset this.
[0051] Step 3: Figure 4 As shown, the 4-port Wheatstone bridge prepared in step 2 is first bonded to the adapter board, and then placed in the cavity of the LTCC electromagnet prepared in step 1.
[0052] The four wires from the Wheatstone bridge (A, B, C, and D) are connected to the outside of the LTCC electromagnet via an adapter board to facilitate connection to the external electrodes. The lead-in and lead-out terminals of the winding coil are moved to the surface of the LTCC electromagnet and marked with IN and OUT electrodes, respectively, to facilitate external circuit connection.
[0053] Step 4. In this embodiment, when the magnetic latching switch is switched to the "on" state, the applied magnetic field is in the +y direction; when switched to the "off" state, the applied magnetic field is in the -y direction. No current pulse is applied to the LTCC electromagnet when switching is not required. When forming a Wheatstone bridge, the four GMR magnetoresistive elements, R1 to R4, are positioned so that the pinning fields of R1 and R3 are parallel to the +y direction, and the pinning fields of R2 and R4 are parallel to the -y direction. Therefore, when a magnetic field in the +y direction is applied by the LTCC electromagnet, the output voltages at the C and D terminals of the Wheatstone bridge are positive, and the entire magnetic latching switch is turned on. Conversely, when a magnetic field in the -y direction is applied by the LTCC magnet, the output voltages at the C and D terminals of the Wheatstone bridge are negative, and the entire magnetic latching switch is turned off.
[0054] In use: A and B are the current input and output terminals of the Wheatstone bridge, and C and D are the voltage detection terminals. A 5mA detection current is passed between A and B. At this point, the voltage level at terminal C is higher than that at terminal D. The externally connected comparator switch circuit compares the voltage levels at terminals C and D. When the voltage level at terminals C is higher than that at terminals D, the MOSFET switch conducts normally, connecting the main circuit to the load. To switch, a 250mA reverse pulse current with a pulse width of 1ms is passed between the electromagnet IN and OUT terminals. This transient magnetic field changes the resistance of the four GMR magnetoresistive elements, causing the voltage level at terminals C to fall below that at terminals D. The comparator then compares the voltage level at terminals C and D, turning off the MOSFET switch and disconnecting the comparator switch circuit.
[0055] If you need to switch it back to the on state, just pass a 250mA forward pulse current between IN and OUT.
[0056] As can be seen from the above embodiments, the present invention uses a magnetoresistive unit to form a Wheatstone bridge, which is placed in the cavity of an LTCC electromagnet and supplemented by a comparator switching circuit. By simply applying positive and reverse current pulses to the LTCC electromagnet, the magnetoresistive state of the magnetoresistive unit undergoes a highly sensitive, controllable, non-volatile flip under the magnetic field H provided by the LTCC electromagnet cavity, thereby achieving state switching of the entire magnetic latching switch through the comparator switching circuit. This replaces the armature switch in traditional magnetic latching switches and eliminates the uncertainty of mechanical switching. Furthermore, because the present invention uses LTCC three-dimensional stacking technology to implement the electromagnet circuit, it is extremely beneficial to the consistency of overall product performance and miniaturized integration, resulting in extremely high reliability. It is particularly suitable for aerospace and other magnetic latching switch applications with high requirements for reliability and integration.
Claims
1. A magnetic latching switch based on LTCC integration, characterized by: Including LTCC electromagnet and magnetoresistive unit; The LTCC electromagnet is provided with a cavity for accommodating a magnetoresistive unit. When a pulse current is applied to the winding coil of the LTCC electromagnet winding, a magnetic field H generated in the cavity causes the magnetoresistive unit placed in the cavity to undergo magnetic reversal. There are four magnetoresistive units, corresponding to R1 to R4, and the magnetoresistive units R1 to R4 form a Wheatstone bridge; When forming a Wheatstone bridge, the four magnetoresistive units R1 to R4 are placed so that the pinning fields of R1 and R3 are parallel to the +y direction, and the pinning fields of R2 and R4 are parallel to the -y direction. The entire Wheatstone bridge structure is a four-port device, with A being the current input terminal, B being the current output terminal, and C and D being the voltage detection terminals. Among them, a detection current flows between A and B, and a comparator switch circuit is externally connected to the C and D ends. The detection current is provided by the steady-state working current of the comparator switch circuit; the comparator switch circuit compares the voltage levels of the C and D ends: when the voltage level of the C end is higher than that of the D end, the comparator outputs a high level, the switch MOS tube connected to it is turned on, and the working circuit is turned on; when the voltage level of the C end is lower than that of the D end, the comparator outputs a low level, the switch MOS tube connected to it is turned off, and the working circuit is also turned off.
2. The LTCC-based integrated magnetic latching switch according to claim 1, wherein: The winding of the LTCC electromagnet is a combined structure of planar winding and three-dimensional lamination.
3. The LTCC-based integrated magnetic latching switch according to claim 1, wherein: The comparator switch circuit is integrated on the outer surface of the LTCC electromagnet.
4. The LTCC-based integrated magnetic latching switch according to claim 1, wherein: The magnetoresistive unit is a GMR magnetoresistive unit or a TMR magnetoresistive unit.
5. The LTCC integrated magnetic latching switch according to claim 1, wherein: The LTCC electromagnet adopts a double-winding structure or a single-winding structure.
6. The LTCC-based integrated magnetic latching switch according to claim 1, wherein: A transfer board is also added to the cavity of the LTCC electromagnet for transition. The Wheatstone bridge is first bonded to the transfer board, and then the transfer board is placed in the cavity of the LTCC electromagnet. The four wires of the four ports A, B, C, and D of the Wheatstone bridge are led out to the outside of the LTCC electromagnet through the transfer board.
7. The LTCC-based integrated magnetic latching switch according to claim 6, wherein: The adapter board adopts a PCB board, an LTCC or a HTCC substrate.
8. The LTCC integrated magnetic latching switch according to claim 1, wherein: The LTCC ceramic of the LTCC electromagnet is made of non-magnetic dielectric ceramic material or ferrite ceramic material.
9. The method for preparing a magnetic latching switch based on LTCC integration according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: Step 1: Based on the LTCC three-dimensional stacking technology, according to the magnitude of the magnetic field H required for the flipping of the selected magnetoresistive unit, design and process an LTCC electromagnet whose magnetic field H generated in the cavity matches the magnitude of the selected magnetoresistive unit; Step 2: Prepare a Wheatstone bridge corresponding to the selected magnetoresistive unit; Step 3: Place the Wheatstone bridge prepared in step 2 in the cavity of the LTCC electromagnet prepared in step 1, and lead the four leads corresponding to the four ports A, B, C, and D of the Wheatstone bridge to the outside of the LTCC electromagnet; If an adapter plate is added, first fix the Wheatstone bridge on the transition adapter plate, then place it, and then lead out the four leads corresponding to the four ports A, B, C, and D through the adapter plate; Step 4: For the four leads of the Wheatstone bridge terminals A, B, C, and D, a detection current is passed between terminals A and B, and a comparator switch circuit is connected to terminals C and D. Comparator switch circuit: When the C-terminal level is higher than the D-terminal level, the comparator switch is turned on, and the working circuit of the comparator switch circuit is connected to the load; when the C-terminal level is lower than the D-terminal level, the comparator switch is turned off, and the working circuit of the comparator switch circuit is disconnected from the load.
10. The LTCC integrated magnetic latching switch according to claim 1, characterized in that: When using: A forward current pulse with a duration of 0.5 to 10 ms is applied to the LTCC electromagnet, causing the magnetic field provided by the LTCC electromagnet to be in the +y direction. R1 and R3 are in a low resistance state, while R2 and R4 are in a high resistance state. At this time, a 1 to 20 mA detection current is applied to terminals A and B. The comparator detects that the voltage level at terminal C is higher than that at terminal D, causing the external comparator switch to turn on, and the working circuit of the comparator switch circuit is connected to the load. When switching is required, a reverse current pulse with a duration of 0.5 to 10 ms is passed through the LTCC electromagnet, which instantly generates a magnetic field in the -y direction in the electromagnet, causing the states of the four magnetoresistive units to change. R1 and R3 change from their original low resistance state to a high resistance state, while R2 and R4 change from their original high resistance state to a low resistance state. At this time, due to the detection current applied to the A and B terminals, the comparator detects that the level of the C terminal is lower than the level of the D terminal, and the level of the C terminal is lower than the level of the D terminal, triggering the external comparator switch circuit from on to off, and the working circuit of the comparator switch circuit is not conducting; If the switch is switched again, a forward current pulse with a pulse duration of 0.5 to 10 ms is passed to the LTCC electromagnet.