Negative voltage protection circuit

Abstract

The utility model discloses a negative voltage protection circuit, which comprises a negative voltage protection module used for being electrically connected with an input end, and when backward voltage appears in the circuit, the negative voltage protection circuit responds quickly, clamps the backward voltage in a safe working area range of a device and discharges the backward voltage to the ground; the current limiting module is used for limiting the maximum current within a certain threshold value and preventing surge current from causing abnormity of a driving power supply part; the totem pole output and secondary release module is used for driving a driven device and is also used for releasing charges generated on a circuit so as to prevent product damage caused by slow release speed of the circuit; and the forward protection module is used for preventing the device from being damaged when the product is protected and the state is rapidly switched, and ensuring that the device runs in a normal working range. The negative voltage protection circuit does not need an MCU module to detect the input voltage, and the system reliability is improved. And the current-limiting resistor is connected in series with the driving input end, so that surge current is prevented, and the stability of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of negative pressure protection, and particularly relates to a negative pressure protection circuit. Background Art

[0002] In today's society, with the continuous increase in the number of products, products form a huge system with each other. Against the background of mutual interference between products and the complexity of usage scenarios, higher requirements are put forward for the circuit protection of electronic devices. However, the existing circuit protection is single and has certain limitations. As the current of the product is different, the corresponding back electromotive force is also different. According to the formula V = di / dt, the magnitude of the negative pressure is related to both the current and time. When there is a large current, the existing circuit cannot achieve protection and cannot meet the protection requirements of the circuit in various scenarios. Under this background, it is particularly important and more meaningful to develop a protection circuit with more complete functions and better protection effects. Adding negative pressure protection to the existing circuit can effectively improve the circuit safety, thereby reducing faults and effectively extending the service life and the useful life of the device. Summary of the Utility Model

[0003] To solve the technical problems in the background art, the utility model proposes a negative pressure protection circuit.

[0004] A negative pressure protection circuit proposed by the utility model includes:

[0005] A negative pressure protection module, which is used to be electrically connected to the input end. When a reverse voltage appears in the circuit, the negative pressure protection circuit responds quickly, clamps the reverse voltage within the safe operating area of the device, and discharges it to the ground;

[0006] A current limiting module, which is used to limit the maximum current within a certain threshold to prevent the occurrence of surge current, which may cause abnormalities in the driving power supply part;

[0007] A totem pole output and secondary release module, which is used to drive the driven device and also used to release the charge generated on the circuit to prevent product damage caused by slow circuit release speed;

[0008] A forward protection module, which is used to prevent device damage caused by the product during protection and rapid switching of states, and ensure that the device operates within the normal working range;

[0009] Among them, one end of the negative pressure protection module is electrically connected to the input end, the other end of the negative pressure protection module is electrically connected to the first end of the totem pole output and secondary release module, the second end of the totem pole output and secondary release module is electrically connected to one end of the current limiting module, and the third end of the totem pole output and secondary release module is electrically connected to one end of the forward protection module.

[0010] Preferably, the negative pressure protection module includes a resistor R2, a resistor R5, a resistor R6, a resistor R8, a triode Q3, and a diode D2. One end of the resistor R5 is electrically connected to one end of the resistor R6. One end of the resistor R5 is connected to the voltage VCC1. The other end of the resistor R5 is electrically connected to the emitter of the triode Q3. The base of the triode Q3 is electrically connected to the other end of the resistor R6. The collector of the triode Q3 is electrically connected to the positive electrode of the diode D2. The negative electrode of the diode D2 is electrically connected to one end of the resistor R2. The other end of the resistor R2 is electrically connected to the first end of the totem pole output and secondary release module. The other end of the resistor R6 is electrically connected to one end of the resistor R8. The other end of the resistor R8 is grounded.

[0011] Preferably, the current limiting module includes a resistor R1 and a diode D1. One end of the resistor R1 is electrically connected to the negative electrode of the diode D1. The other end of the resistor R1 is electrically connected to the second end of the totem pole output and secondary release module.

[0012] Preferably, the totem pole output and secondary release module includes a resistor R7, a triode Q4, a triode Q2, a triode Q1, a diode D3, and a resistor R9. One end of the resistor R7 is electrically connected to the base of the triode Q4. The other end of the resistor R7 is grounded. The emitter of the triode Q4 is electrically connected to one end of the resistor R9. The collector of the triode Q4 is grounded. The other end of the resistor R9 is electrically connected to the base of the triode Q2. The emitter of the triode Q2 is electrically connected to the emitter of the triode Q1. The emitter of the triode Q1 is electrically connected to the positive electrode of the diode D3. The base of the triode Q1 is electrically connected to the negative electrode of the diode D3. The collector of the triode Q2 is grounded.

[0013] Preferably, one end of the resistor R7 is the first end of the totem pole output and secondary release module. The collector of the triode Q1 is the second end of the totem pole output and secondary release module. The emitter of the triode Q2 is the third end of the totem pole output and secondary release module.

[0014] Preferably, the positive protection module specifically includes a resistor R3, a zener diode DZ1, and a capacitor C1. One end of the resistor R3 is electrically connected to one end of the capacitor C1. One end of the capacitor C1 is electrically connected to the negative electrode of the zener diode DZ1. The positive electrode of the zener diode DZ1 is grounded. The other end of the capacitor C1 is grounded. The other end of the resistor R3 is electrically connected to the third end of the totem pole output and secondary release module.

[0015] In this utility model, the proposed negative pressure protection circuit limits the maximum current within a certain threshold through a current limiting module to prevent large current switching from causing surge current and resulting in abnormalities in the drive power supply part. The drive circuit promotes the totem pole output. The totem pole output and the secondary release module are the diode amplification and release circuits externally connected to the totem pole circuit, which is to prevent the slow closing of the totem pole caused by large current. Through diode amplification and release, the release current can be further amplified to accelerate the release current of the totem pole. At the same time, it can meet the application scenario of small current controlling large current and further reduce the power consumption of the entire system. The negative pressure protection module is composed of a diode and a triode to jointly form negative pressure protection. When the negative pressure protection module is 0V and there is a negative pressure value in the positive protection module, if there is no negative pressure protection module at this time, the voltage across the D2 diode is the forward voltage and the diode conducts, there is a risk of incorrect activation of the totem pole. Due to the presence of the triode Q3, D2 is in a floating state, which prevents D2 from conducting, thus playing the role of negative pressure protection and making up for the defects in the design of the existing circuit. There is no need for the MCU module to detect the input voltage. The input voltage is connected to the voltage dividing resistor through a one-way conduction to drive the hardware to conduct. When the input is reverse-connected, due to the one-way conduction, the drive voltage is 0V at this time, which is default not connected to the power supply and does not turn on the input, completing the reverse connection protection and improving the reliability of the system. A current limiting resistor is connected in series at the drive input end to limit the maximum input current, prevent the occurrence of surge current, and improve the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic circuit diagram of a negative pressure protection circuit proposed by this utility model;

[0017] Figure 2 FIG. is a schematic diagram of the negative pressure protection occurrence structure of a negative pressure protection circuit proposed by this utility model;

[0018] Figure 3 FIG. is a schematic diagram of the multi-protection mechanism structure of a negative pressure protection circuit proposed by this utility model;

[0019] Figure 4 FIG. is a schematic diagram of the circuit implementation structure of a negative pressure protection circuit proposed by this utility model. DETAILED IMPLEMENTATION MANNER

[0020] Refer to Figures 1-4 , a negative pressure protection circuit proposed by this utility model includes:

[0021] A negative pressure protection module, which is used to be electrically connected to the input end. When a reverse voltage appears in the circuit, the negative pressure protection circuit responds quickly, clamps the reverse voltage within the safe operating area of the device, and discharges it to the ground;

[0022] A current limiting module, used to limit the maximum current within a certain threshold to prevent surge current from causing abnormalities in the drive power supply part;

[0023] A totem pole output and secondary release module, used to drive the device to be driven and also used to release the charge generated on the circuit to prevent product damage caused by slow circuit release speed;

[0024] A positive protection module, used to prevent device damage caused by the product during protection occurrence and rapid switching states, ensuring that the device operates within the normal working range;

[0025] Among them, one end of the negative voltage protection module is electrically connected to the input end, the other end of the negative voltage protection module is electrically connected to the first end of the totem pole output and secondary release module, the second end of the totem pole output and secondary release module is electrically connected to one end of the current limiting module, and the third end of the totem pole output and secondary release module is electrically connected to one end of the positive protection module.

[0026] In this embodiment, first, the drive voltage is fixed at a constant value by DC-DC, and the maximum current is limited within a certain threshold by the current limiting module to prevent surge current caused by large current switching from resulting in abnormalities in the drive power supply part. The drive circuit drives the totem pole output. The totem pole output and secondary release module is an external diode amplification and release circuit for the totem pole circuit, which is to prevent the totem pole from closing slowly due to large current. Through diode amplification and release, the release current can be further amplified to accelerate the totem pole release current, and at the same time, it can meet the application scenario of small current controlling large current, which can further reduce the power consumption of the entire system. The negative voltage protection module is composed of a diode and a triode to jointly form negative voltage protection. When the negative voltage protection module is 0V and there is a negative voltage value in the positive protection module, at this time, if there is no negative voltage protection module, the voltage across the D2 diode is a forward voltage, and the diode conducts, there is a risk of totem pole mis - opening. Due to the presence of the triode Q3, D2 is in a floating state, which prevents D2 from conducting, thus playing the role of negative voltage protection and making up for the defects in the design of the existing circuit.

[0027] Specifically, as Figure 4 shown, the negative voltage protection module includes resistor R2, resistor R5, resistor R6, resistor R8, triode Q3, and diode D2. One end of resistor R5 is electrically connected to one end of resistor R6. One end of resistor R5 is connected to voltage VCC1. The other end of resistor R5 is electrically connected to the emitter of triode Q3. The base of triode Q3 is electrically connected to the other end of resistor R6. The collector of triode Q3 is electrically connected to the positive electrode of diode D2. The negative electrode of diode D2 is electrically connected to one end of resistor R2. The other end of resistor R2 is electrically connected to the first end of the totem pole output and secondary release module. The other end of resistor R6 is electrically connected to one end of resistor R8. The other end of resistor R8 is grounded.

[0028] Specifically, as Figure 4 shown, the current limiting module includes a resistor R1 and a diode D1. One end of the resistor R1 is electrically connected to the negative electrode of the diode D1, and the other end of the resistor R1 is electrically connected to the second end of the totem pole output and the secondary release module.

[0029] Specifically, as Figure 4 shown, the totem pole output and the secondary release module includes a resistor R7, a triode Q4, a triode Q2, a triode Q1, a diode D3, and a resistor R9. One end of the resistor R7 is electrically connected to the base of the triode Q4, the other end of the resistor R7 is grounded, the emitter of the triode Q4 is electrically connected to one end of the resistor R9, the collector of the triode Q4 is grounded, the other end of the resistor R9 is electrically connected to the base of the triode Q2, the emitter of the triode Q2 is electrically connected to the emitter of the triode Q1, the emitter of the triode Q1 is electrically connected to the positive electrode of the diode D3, the base of the triode Q1 is electrically connected to the negative electrode of the diode D3, and the collector of the triode Q2 is grounded.

[0030] It should be noted that the triode has an amplification effect, with a typical value of β = 100. Theoretically, the secondary series amplification factor β = 100 * 100. Using this characteristic, a small current can be used to control a large current. When a current of 100 μA is input to the base of the first-stage triode, a current of 1 A is output at the emitter of the secondary amplification. Through the above characteristics, a micro-current control large-current circuit can be designed. The micro-current requires a small current and will not interfere with the control part of the circuit and affect the operation of the product, which can significantly improve the stability and reliability of the control system and extend the service life of the product.

[0031] Specifically, as Figure 4 shown, one end of the resistor R7 is the first end of the totem pole output and the secondary release module, the collector of the triode Q1 is the second end of the totem pole output and the secondary release module, and the emitter of the triode Q2 is the third end of the totem pole output and the secondary release module.

[0032] In this embodiment, to prevent insufficient operating current during protection activation, multiple-stage amplification is added to ensure rapid release of the residual current during protection activation. When the product is not under protection, the protection device is at the same potential as the ground due to its own characteristics.

[0033] Specifically, as Figure 4 shown, the forward protection module specifically includes a resistor R3, a zener diode DZ1, and a capacitor C1. One end of the resistor R3 is electrically connected to one end of the capacitor C1, one end of the capacitor C1 is electrically connected to the negative electrode of the zener diode DZ1, the positive electrode of the zener diode DZ1 is grounded, the other end of the capacitor C1 is grounded, and the other end of the resistor R3 is electrically connected to the third end of the totem pole output and the secondary release module.

[0034] It should be noted that as is well known, in an environment where there are wires and a magnetic field exists, a wire can be equivalent to a tiny inductor. When the circuit switches rapidly or the control part loses power abnormally, the equivalent inductor circuit will generate a back electromotive force. At this time, if there is no negative voltage protection, passive devices may be damaged or destroyed. Based on the above circuit characteristics, a set of negative voltage protection circuits is designed. When circuit protection occurs, a reverse voltage is generated in the protection circuit at this time. Through the negative voltage protection circuit, the entire reverse voltage is clamped within the safe operating area of the device and discharged to the ground, finally making the entire circuit equipotential and completing the negative voltage protection.

[0035] In this embodiment, for the proposed negative voltage protection circuit, most of the existing protection circuits only have forward protection, which cannot meet the increasing complexity of various working conditions and usage scenarios, and may cause product damage due to improper circuit protection. Adding multiple protection mechanisms on the existing basis can effectively prevent product abnormalities caused by circuit damage. When protection occurs, the forward protection circuit clamps the device in the safe operating area, and the negative voltage protection can clamp the negative voltage in the entire loop in the safe operating area. At this time, the discharge circuit quickly discharges the remaining charges to the ground, finally achieving equipotential between the protection devices and completing the protection function. At the same time, each passive device participating in the clamping also has its own protection circuit to prevent damage to the clamping circuit devices.

[0036] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A negative pressure protection circuit, characterized in that, Including: A negative voltage protection module, which is used to be electrically connected to the input terminal. When a reverse voltage appears in the circuit, the negative voltage protection circuit responds quickly, clamps the reverse voltage within the safe operating area of the device, and discharges it to the ground; A current limiting module, which is used to limit the maximum current within a certain threshold to prevent the occurrence of inrush current and thus cause abnormalities in the drive power supply part; A totem pole output and secondary release module, which is used to drive the device to be driven and also used to release the charge generated on the circuit to prevent product damage caused by slow circuit release speed; A forward protection module, which is used to prevent device damage caused by the product during protection and rapid switching states, and ensure that the device operates within the normal operating range; Among them, one end of the negative voltage protection module is electrically connected to the input terminal, the other end of the negative voltage protection module is electrically connected to the first end of the totem pole output and secondary release module, the second end of the totem pole output and secondary release module is electrically connected to one end of the current limiting module, and the third end of the totem pole output and secondary release module is electrically connected to one end of the forward protection module.

2. The negative pressure protection circuit according to claim 1, wherein The negative voltage protection module includes resistor R2, resistor R5, resistor R6, resistor R8, triode Q3, and diode D2. One end of resistor R5 is electrically connected to one end of resistor R6. One end of resistor R5 is connected to voltage VCC1. The other end of resistor R5 is electrically connected to the emitter of triode Q3. The base of triode Q3 is electrically connected to the other end of resistor R6. The collector of triode Q3 is electrically connected to the positive electrode of diode D2. The negative electrode of diode D2 is electrically connected to one end of resistor R2. The other end of resistor R2 is electrically connected to the first end of the totem pole output and secondary release module. The other end of resistor R6 is electrically connected to one end of resistor R8. The other end of resistor R8 is grounded.

3. The negative pressure protection circuit according to claim 1, characterized in that, The current limiting module includes resistor R1 and diode D1. One end of resistor R1 is electrically connected to the negative electrode of diode D1. The other end of resistor R1 is electrically connected to the second end of the totem pole output and secondary release module.

4. The negative pressure protection circuit according to claim 1, characterized in that The totem pole output and secondary release module includes resistor R7, triode Q4, triode Q2, triode Q1, diode D3, and resistor R9. One end of resistor R7 is electrically connected to the base of triode Q4. The other end of resistor R7 is grounded. The emitter of triode Q4 is electrically connected to one end of resistor R9. The collector of triode Q4 is grounded. The other end of resistor R9 is electrically connected to the base of triode Q2. The emitter of triode Q2 is electrically connected to the emitter of triode Q1. The emitter of triode Q1 is electrically connected to the positive electrode of diode D3. The base of triode Q1 is electrically connected to the negative electrode of diode D3. The collector of triode Q2 is grounded.

5. The negative pressure protection circuit according to claim 4, wherein One end of resistor R7 is the first end of the totem pole output and secondary release module. The collector of triode Q1 is the second end of the totem pole output and secondary release module. The emitter of triode Q2 is the third end of the totem pole output and secondary release module.

6. The negative pressure protection circuit according to claim 1, characterized in that The forward protection module specifically includes a resistor R3, a zener diode DZ1, and a capacitor C1. One end of the resistor R3 is electrically connected to one end of the capacitor C1. One end of the capacitor C1 is electrically connected to the negative electrode of the zener diode DZ1. The positive electrode of the zener diode DZ1 is grounded. The other end of the capacitor C1 is grounded. The other end of the resistor R3 is electrically connected to the third terminal of the lifting column output and the secondary release module.

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