Self-protection circuit of bistable switch

Abstract

The utility model discloses a self-protection circuit of a bistable switch. The self-protection circuit comprises a power supply module and an MCU module powered by the power supply module. The circuit further comprises a coil driving module, the coil driving module comprises sub-coil driving modules capable of conducting suction control and disconnection control on the two coils respectively, and the two sub-coil driving modules are connected with the enabling end of the MCU module respectively. And a resettable fuse is connected in series between the coil driving module and the power supply module. The utility model has the following advantages and effects: the circuit has a current protection / short circuit protection function, an overheat protection function and a self-recovery function, has the advantage of simple circuit, can effectively reduce the cost expenditure, and is convenient for subsequent maintenance.

Description

Technical Field

[0001] This utility model relates to switching circuits, and in particular to a self-protection circuit for a bistable switch. Background Technology

[0002] Switching circuits are a common control method in automotive circuits, controlling the on / off state of the circuit. In practical applications, power supply switching circuits often lack protection functions. In the event of an internal malfunction, the switching circuit's inability to self-protect can lead to a vehicle fire, posing a risk of vehicle damage. The following optimizations are needed for switching circuits: 1. Add overcurrent / short-circuit protection; 2. Add overheat protection; 3. Add self-recovery functionality. Utility Model Content

[0003] The purpose of this invention is to provide a self-protection circuit for a bistable switch, which has overcurrent / short-circuit protection, overheat protection, and self-recovery functions, enabling self-protection in case of product malfunctions and avoiding the risk of vehicle fire.

[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0005] A self-protection circuit for a bistable switch includes a power supply module and an MCU module powered by the power supply module; it also includes a coil driving module, wherein the coil driving module includes sub-coil driving modules that can respectively control the activation and deactivation of two coils, and the two sub-coil driving modules are respectively connected to the enable terminal of the MCU module.

[0006] The coil drive module is powered by the power supply module, and a self-resetting fuse is connected in series between the two.

[0007] Furthermore, both of the aforementioned sub-coil drive modules include a switch control element, which has a control terminal. The control terminal of the switch control element is connected to the enable terminal of the MCU module. The switch control element is connected to the power supply circuit of the corresponding coil and controls the on / off state of the power supply circuit based on the output of the enable terminal of the MCU module.

[0008] Furthermore, the switching control element is a MOSFET.

[0009] Furthermore, the sub-coil drive module also includes a first resistor, a second resistor, and a TVS diode. One end of the first resistor is connected to the enable terminal of the MCU module, and the other end is connected to one end of the second resistor and the gate of the MOSFET. The other end of the second resistor and the source of the MOSFET are both grounded. The drain of the MOSFET is connected to one end of the coil and one end of the TVS diode. The other end of the coil is connected to a resettable fuse, and the other end of the TVS diode is grounded.

[0010] Furthermore, the sub-coil driving module also includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the drain of the MOS transistor, the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is grounded.

[0011] Furthermore, it also includes a voltage sampling circuit, which feeds back the voltage on the terminal block to the MCU module.

[0012] Furthermore, the model number of the MCU module is R5F10268.

[0013] Furthermore, the power supply module includes a step-down chip IC1.

[0014] Furthermore, the power supply module includes two reverse polarity protection diodes, D4 and D5, connected to the terminal block.

[0015] Furthermore, it also includes a signal input / output selection circuit that connects to the MCU module.

[0016] This utility model has the following beneficial effects:

[0017] 1. Overcurrent protection / short circuit protection:

[0018] If the current to engage or disengage the coil is ≥6A, the coil drive module will stop driving.

[0019] When the current of the coil being engaged or disengaged exceeds its maximum set value of 6A, the resettable fuse enters a high-resistance state, making the power supply VCC1 of the coil being engaged or disengaged less than 2V, so that the coil being engaged or disengaged cannot be driven, and the protective components will not be damaged, thus protecting the product from burning.

[0020] 2. Overheat protection:

[0021] When the operating temperature is >125℃, the protection current of the self-resetting fuse is less than the driving current (the higher the temperature, the lower the protection current of the self-resetting fuse), triggering the self-resetting fuse to enter a high-resistance state, so that the power supply VCC1 of the coil engaging or disengaging is <2V, making it impossible to drive the coil engaging or disengaging, thereby protecting the product from burning out.

[0022] 3. Self-resetting fuses have a self-resetting function. Attached Figure Description

[0023] Figure 1 This is a circuit schematic diagram of the coil driving module in the embodiment;

[0024] Figure 2 This is a circuit diagram of the voltage sampling circuit in the embodiment;

[0025] Figure 3 This is a circuit schematic of the MCU module in the embodiment;

[0026] Figure 4 This is a circuit diagram of the power supply module in the embodiment;

[0027] Figure 5 This is a circuit schematic of the high-side input circuit in the embodiment;

[0028] Figure 6 This is a circuit schematic of the low-side input circuit in the embodiment;

[0029] Figure 7 This is a circuit diagram of the high-side output circuit in the embodiment. Detailed Implementation

[0030] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0031] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0032] As attached Figures 1 to 7 As shown, this embodiment discloses a self-protection circuit for a bistable switch, including a power supply module and an MCU module powered by the power supply module; it also includes a coil driving module, which includes sub-coil driving modules that can respectively control the activation and deactivation of two coils, and the two sub-coil driving modules are respectively connected to the enable terminal of the MCU module;

[0033] The schematic diagram of the coil drive circuit is attached. Figure 1 As shown, the two coils are denoted as the disconnect coil and the pull-in coil, respectively. The disconnect coil and the pull-in coil are connected to terminals JP1 and JP2, respectively. The coil drive circuit includes two sub-coil drive modules, which control the product switch pull-in and the product switch release, respectively.

[0034] The coil drive module is powered by the power supply module, and a self-resetting fuse is connected in series between the two; the self-resetting fuse corresponds to the attached... Figure 1 In the FU1 section, the resettable fuse is connected in series between VCC and VCC1.

[0035] Both sub-coil drive modules include a switch control element. The switch control element has a control terminal, which is connected to the enable terminal of the MCU module. The switch control element is connected to the power supply circuit of the corresponding coil and controls the on / off state of the power supply circuit based on the output of the enable terminal of the MCU module.

[0036] In the sub-coil drive module, the coil is an open coil, and the switch control element corresponds to MOSFET Q1, which is an N-channel MOSFET; in the sub-coil drive module, the coil is an closed coil, and the switch control element corresponds to MOSFET Q2, which is an N-channel MOSFET.

[0037] like Figure 1 As shown, the two sub-coil drive modules correspond to the disconnect coil circuit and the pull-in coil circuit, respectively. When the sub-coil module is the disconnect coil circuit, it includes a first resistor R4, a second resistor R24, and a TVS diode, which corresponds to TVS2. One end of the first resistor R4 is connected to the enable terminal of the MCU module, and the other end is connected to one end of the second resistor R24 ​​and the gate of the MOSFET Q1. The other end of the second resistor R24 ​​and the source of the MOSFET Q1 are both grounded. The drain of the MOSFET Q1 is connected to one end of the disconnect coil and one end of TVS2. The other end of the disconnect coil is connected to the resettable fuse, and the other end of TVS2 is grounded.

[0038] When the sub-coil module is a pull-in coil circuit, it includes a first resistor R16, a second resistor R25, and a TVS diode, which corresponds to TVS3. One end of the first resistor R16 is connected to the enable terminal of the MCU module, and the other end is connected to one end of the second resistor R25 and the gate of the MOSFET Q2. The other end of the second resistor R25 and the source of the MOSFET Q2 are both grounded. The drain of the MOSFET Q2 is connected to one end of the pull-in coil and one end of TVS3. The other end of the pull-in coil is connected to the resettable fuse, and the other end of TVS3 is grounded.

[0039] The sub-coil drive module also includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the drain of the MOS transistor, and the other end of the first capacitor is connected to one end of the second capacitor. The other end of the second capacitor is grounded.

[0040] As attached Figure 1 As shown, in the first sub-coil driving module, the first capacitor corresponds to C7 and the second capacitor corresponds to C8; in the second sub-coil driving module, the first capacitor corresponds to C14 and the second capacitor corresponds to C15.

[0041] This also includes a voltage sampling circuit, which feeds back the voltage at the terminals to the MCU module; the circuit diagram of the voltage sampling circuit is attached. Figure 2As shown, the voltage sampling of pin 30 (input / output pin) is: through D1, then through voltage divider R13 / R15, filter C13, and then through current-limiting resistor to MCU; the voltage sampling of pin 87 (input / output pin) is: through D6, then through voltage divider R17 / R19, filter C16, and then through current-limiting resistor to MCU. D1 and D6 prevent crosstalk between pins 30 and 87; the voltage sampling of pins 30 and 87 provides overvoltage protection (>32V) and undervoltage protection (<16V) for the product.

[0042] The MCU module model is R5F10268; please refer to the attached document for details. Figure 3 .

[0043] The power supply module includes a step-down chip IC1, which can be an LM2930. The circuit diagram of the power supply module is attached. Figure 4 As shown, pins 30 and 87 are the power input / output pins of the switch. If power 30 is the input, it goes to VCC through diode D5 (when power 87 is the input, it goes to pin 87 through D4). VCC then goes to the step-down chip IC1 through current-limiting resistors R1 / R2 / R3, and is then converted to 5V (VDD) by the step-down chip IC1. Diodes D4 and D5 prevent reverse connection and input / output leakage current. Capacitors C1 / C5 / C17 / C18 are for port electrostatic discharge protection. TVS1 prevents transient pulses from damaging IC1. R1 / R2 / R3 are current-limiting resistors. C2 / C6 / C3 / C4 are filter capacitors.

[0044] The power supply module includes two reverse polarity protection diodes, D4 and D5, connected to the terminals, as shown in the attached diagram. Figure 4 As shown;

[0045] This also includes a signal input / output selection circuit connected to the MCU module. The signal input / output selection circuit includes a high-side input circuit, a low-side input circuit, and a high-side output circuit; the high-side input circuit is shown in the attached diagram. Figure 5 As shown, the high-side input circuit includes resistors R10, R7, and R9, capacitors C9 and C11. One end of resistor R10 is connected to the high-level input pin and one end of capacitor C9. The other end of capacitor C9 is connected to capacitor C11, and the other end of capacitor C11 is grounded. The other end of resistor R10 is connected to resistors R7 and R9, and the other end of resistor R9 is grounded. The other end of resistor R7 is connected to the MCU. The high-level input signal is divided by resistors R10 and R9, and then passes through the current-limiting resistor R7 to the MCU module for signal judgment.

[0046] The low-side input circuit is shown in the attached diagram. Figure 6As shown, the low-side input circuit includes resistors R5 and R7, diode D2, capacitor C9, and capacitor C11. One end of resistor R7 is connected to the positive terminals of resistor R5 and diode D2, and the other end of resistor R7 is connected to the MCU. The other end of resistor R5 is connected to VDD. The negative terminal of diode D2 is connected to capacitor C9 and the low-side output pin. The other end of capacitor C9 is connected to capacitor C11, and the other end of capacitor C11 is grounded. VDD is connected to the low-level input signal through the current-limiting resistor R5 and diode D2. The MCU module samples the voltage value at the Sin_Out point through the current-limiting resistor R7 to determine the low-side input signal.

[0047] The high-side output circuit is shown in the attached diagram. Figure 7 As shown, the high-side output circuit includes resistor R20, NPN transistor Q6, resistor R34, resistor R33, PNP transistor Q3, resistor R32, diode D2, capacitor C9, and capacitor C11. One end of resistor R20 is connected to the MCU, and the other end of resistor R20 is connected to the base of NPN transistor Q6. The emitter of NPN transistor Q6 is grounded, and the collector is connected to one end of resistor R34. The other end of resistor R34 is connected to resistor R33 and the base of PNP transistor Q3. The other end of resistor R33 is connected to VCC and the emitter of PNP transistor Q3. The collector of PNP transistor Q3 is connected to resistor R32, and the other end of resistor R32 is connected to the positive terminal of diode D2. One end of capacitor C9 is connected to the negative terminal of diode D2 and the high-side output pin, and the other end of capacitor C9 is connected to capacitor C11. The other end of capacitor C11 is grounded. The MCU controls NPN transistor Q6 to conduct through R20, and controls PNP transistor Q3 to conduct, so that VCC is output to the high-side output pin STOP through Q3 / R32 / D2. Among them, R33 / R24 are current limiting and bias resistors, and C9 / C11 are port anti-static capacitors.

[0048] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A self-protection circuit for a bistable switch, comprising a power supply module and an MCU module powered by the power supply module; characterized in that: It also includes a coil driving module, which includes a sub-coil driving module that can control the coil to engage and disengage respectively. The two sub-coil driving modules are respectively connected to the enable terminal of the MCU module. The coil drive module is powered by the power supply module, and a self-resetting fuse is connected in series between the two.

2. The self-protection circuit of a bistable switch according to claim 1, characterized in that: Both of the aforementioned sub-coil drive modules include a switch control element, which has a control terminal. The control terminal of the switch control element is connected to the enable terminal of the MCU module. The switch control element is connected to the power supply circuit of the corresponding coil and controls the on / off state of the power supply circuit based on the output of the enable terminal of the MCU module.

3. The self-protection circuit of a bistable switch according to claim 2, characterized in that: The switch control element is a MOSFET.

4. The self-protection circuit of a bistable switch according to claim 3, characterized in that: The sub-coil drive module further includes a first resistor, a second resistor, and a TVS diode. One end of the first resistor is connected to the enable terminal of the MCU module, and the other end is connected to one end of the second resistor and the gate of the MOS transistor. The other end of the second resistor and the source of the MOS transistor are both grounded. The drain of the MOS transistor is connected to one end of the coil and one end of the TVS diode. The other end of the coil is connected to a resettable fuse, and the other end of the TVS diode is grounded.

5. The self-protection circuit of a bistable switch according to claim 4, characterized in that: The sub-coil driving module further includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the drain of the MOS transistor, the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is grounded.

6. The self-protection circuit of a bistable switch according to claim 1, characterized in that: It also includes a voltage sampling circuit, which feeds back the voltage on the terminal block to the MCU module.

7. The self-protection circuit of a bistable switch according to claim 1, characterized in that: The MCU module in question is model R5F10268.

8. The self-protection circuit of a bistable switch according to claim 1, characterized in that: The power supply module includes a step-down chip IC1.

9. The self-protection circuit of a bistable switch according to claim 1, characterized in that: The power supply module includes two reverse polarity protection diodes, D4 and D5, connected to the terminal block.

10. The self-protection circuit of a bistable switch according to claim 1, characterized in that: It also includes a signal input / output selection circuit that connects to the MCU module.

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