A self-restoring fuse-based TVS tube leakage current rapid discrimination circuit

Abstract

The utility model relates to electronic circuit detection technical field, concretely disclose a kind of TVS pipe leakage current quick discrimination circuit based on self-restoration fuse, including power module, protection module, sampling module, signal amplification module, discrimination module and indication alarm module, sampling module detects TVS pipe leakage current by sampling resistance, and conversion voltage signal, signal amplification module uses operational amplifier, gain is adjustable to 10 times, 100 times, 1000 times, discrimination module is composed of stabilivolt and voltage comparison circuit, LED pilot lamp is used for alarm, when the signal voltage after amplification exceeds stabilivolt threshold value, LED lights up, prompt TVS pipe leakage current exceeds standard, the utility model can quickly, accurately detect TVS pipe leakage current state, judge whether it deteriorates, improve the security and reliability of electronic circuit.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit testing technology, specifically a TVS tube leakage current fast discrimination circuit based on a self-resetting fuse. Background Technology

[0002] With the rapid development of electronic technology, the integration of various electronic devices is constantly increasing, and the demand for circuit protection is becoming increasingly stringent. In power and signal interface circuits, transient voltage suppressor diodes (TVS) are widely used in scenarios such as lightning protection, surge protection, and electrostatic discharge (ESD) protection because they can absorb large current surges and suppress transient overvoltages in a short time. However, after long-term use or exposure to overvoltage surges, the internal PN junction of a TVS diode may deteriorate, leading to an increase in leakage current (IR), which in turn affects the normal operation of the circuit and may even cause safety hazards. Therefore, effectively monitoring the health status of TVS diodes and promptly identifying and replacing degraded components is an important issue in ensuring the safe and reliable operation of circuits.

[0003] Existing TVS tube testing methods mainly include offline testing and online monitoring:

[0004] Offline testing: High-precision multimeters or professional testers are usually used to measure the reverse leakage current of TVS diodes. However, this method requires removing the TVS diode from the circuit for measurement, which not only increases the maintenance workload, but is also not suitable for real-time monitoring scenarios.

[0005] Online monitoring: Some circuits use high-precision operational amplifiers and analog-to-digital converters (ADCs) to detect the leakage current of TVS transistors. However, such solutions are often costly, complex to implement, and have high requirements for power consumption and stability. Therefore, they are difficult to promote in some cost-sensitive or structurally limited applications.

[0006] To address the aforementioned issues, this patent proposes a rapid leakage current detection circuit based on a self-resetting fuse (PPTC) and a TVS diode. This circuit can achieve real-time online detection without affecting the normal operation of the TVS diode. Through signal amplification, Zener diode comparison, and indicator alarm modules, it can intuitively determine the health status of the TVS diode and promptly prompt the user to replace damaged components, thereby improving the reliability and safety of the circuit. Utility Model Content

[0007] The purpose of this invention is to provide a TVS diode leakage current fast detection circuit based on a self-resetting fuse, so as to solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a TVS tube leakage current fast discrimination circuit based on a self-resetting fuse, including a power supply module, a protection module, a sampling module, a signal amplification module, a discrimination module, and an indication and alarm module. The power supply module provides a stable DC power supply. The protection module is composed of a self-resetting fuse and a TVS tube. The PPTC is connected in the power supply circuit, and the TVS tube is connected in parallel to the circuit under test.

[0009] According to the above technical solution, the sampling module includes a sampling resistor R1, one end of which is connected to the TVS tube and the other end is grounded, for detecting the leakage current of the TVS tube and converting it into a small voltage signal.

[0010] According to the above technical solution, the signal amplification module adopts an operational amplifier, wherein:

[0011] The non-inverting input (+) of the operational amplifier is connected to the upper end of the sampling resistor R1 to receive the sampled voltage signal;

[0012] The non-inverting input (-) of the op-amp is connected to a voltage divider network consisting of R2 and R3.

[0013] According to the above technical solution, the gain of the operational amplifier is determined by the feedback resistors R4 (10KΩ), R5 (90KΩ), and R6 (900KΩ), wherein:

[0014] When R4 (10KΩ) is selected, the gain is 10 times, which is suitable for leakage current in the range of 100μA.

[0015] When R5 (90KΩ) is selected, the gain is 100 times, which is suitable for leakage current in the range of 10μA.

[0016] When R6 (900KΩ) is selected, the gain is 1000 times, which is suitable for leakage current in the range of 1μA.

[0017] According to the above technical solution, the discrimination module includes a Zener diode (8.4V) and a voltage detection circuit, wherein:

[0018] The output of the operational amplifier is connected to the anode of the Zener diode, and the cathode of the Zener diode is grounded.

[0019] When the operational amplifier output voltage is below 8.4V, the Zener diode is in the off state;

[0020] When the op-amp output voltage exceeds 8.4V, the Zener diode turns on, providing current to the indicator and alarm module.

[0021] According to the above technical solution, the indicator alarm module includes a current-limiting resistor R7 and an LED indicator, wherein:

[0022] R7 is used to limit the current flowing through the LED to ensure that the LED emits light normally;

[0023] When the Zener diode is turned on, the LED lights up, indicating that the leakage current of the TVS diode has exceeded the set range.

[0024] According to the above technical solution, the reference voltage provided by the voltage divider network R2 and R3 is half of the supply voltage.

[0025] According to the above technical solution, the voltage relationship at the input terminal of the operational amplifier satisfies:

[0026] The sampling voltage is generated by the leakage current of the TVS transistor flowing through the sampling resistor R1;

[0027] The non-inverting input of the op-amp receives the sampled voltage and amplifies it according to the gain set by the feedback resistor;

[0028] By adjusting the feedback resistor, it can be adapted to the leakage current detection requirements of different levels of TVS tubes.

[0029] According to the above technical solution, the function of the self-resetting fuse in the circuit is as follows:

[0030] Limit current in case of overcurrent or short circuit to prevent circuit damage;

[0031] It can automatically restore conduction after the fault is cleared, ensuring that the circuit works normally without the need for manual replacement of the fuse.

[0032] Compared with existing technologies, this invention provides an electronic circuit for quickly detecting the leakage current of a TVS diode, combining a self-resetting fuse (PPTC) and the TVS diode to provide overcurrent and overvoltage protection. The leakage current signal of the TVS diode is acquired through a sampling resistor (R1), and amplified by an operational amplifier with adjustable gain (10x, 100x, 1000x), then analyzed by a Zener diode (8.4V). When the amplified signal voltage exceeds a set threshold, an LED illuminates, indicating that the TVS diode may be deteriorating or damaged.

[0033] This utility model has the following beneficial effects:

[0034] High measurement accuracy – Employs multi-stage amplification circuits to improve the detection sensitivity of minute leakage current signals;

[0035] Rapid response – Real-time monitoring of TVS diode status to prevent circuit failures caused by leakage current degradation;

[0036] Excellent environmental adaptability – The circuit adopts a low-power design, making it suitable for long-term stable operation in different temperature and humidity environments;

[0037] High reliability – PPTC can automatically recover, avoiding circuit damage due to short circuits or overcurrent and extending service life;

[0038] Simplified testing process – no complicated equipment required, LED indicator lights can intuitively display the status of TVS tubes, facilitating on-site maintenance and replacement;

[0039] This invention can quickly and accurately determine the health status of TVS diodes, improve the safety and reliability of electronic circuits, and is applicable to applications such as electronic equipment protection and surge protection. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a circuit diagram of a TVS tube leakage current fast discrimination circuit based on a self-resetting fuse proposed in this utility model; Detailed Implementation

[0042] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0043] Reference Figure 1A TVS diode leakage current fast detection circuit based on a self-resetting fuse includes a power supply module, a protection module, a sampling module, a signal amplification module, a detection module, and an indication and alarm module. The power supply module provides a stable DC power supply to provide the operating voltage for the entire circuit. The protection module consists of a self-resetting fuse (PPTC) and a TVS diode. The PPTC is connected in the power supply circuit and can limit the current under overcurrent or short-circuit conditions, and automatically resumes conduction after the fault is cleared. The TVS diode is connected in parallel with the circuit under test. Its current is small when it is working normally, but its leakage current (IR) will increase after long-term use or after being subjected to overvoltage impact. (The VR value of the TVS diode, i.e., the reverse turn-off voltage, is the highest DC voltage that it can continuously withstand when working normally. This ensures that the TVS is in the cut-off state within this range, with only a very small leakage current flowing through it, avoiding any impact on the circuit.) The sampling module includes a sampling resistor R1 (10KΩ), which is connected in series in the TVS diode circuit. The leakage current IR of the TVS diode is indirectly obtained by measuring the voltage across its terminals, and then converted into a small voltage signal. The signal amplification module uses an operational amplifier, whose non-inverting input (+) is directly connected to the upper end of the sampling resistor R1 (10KΩ) to receive the sampling voltage signal generated across R1 by the IR leakage current of the TVS diode. The magnitude of this voltage signal is proportional to the TVS leakage current; therefore, measuring this voltage indirectly measures the IR leakage current. The non-inverting input (-) of the operational amplifier is connected to a voltage divider network, consisting of R2 (1KΩ) and R3 (1KΩ). The voltage at this voltage divider point is the reference voltage. Where: V cc The reference voltage is the power supply voltage (when the power supply voltage is 5V, the reference potential is approximately 2.5V). It is used to provide a reference voltage for the operational amplifier, ensuring that the signal does not enter the negative voltage region during amplification, thereby improving the stability of the amplifier circuit.

[0044] The gain (amplification factor) of the operational amplifier is determined by the feedback resistors R4 (10KΩ), R5 (90KΩ), and R6 (900KΩ). The specific amplification range is as follows:

[0045] When the feedback resistor is R4 (10KΩ), the gain is 10 times, which is suitable for larger IR currents (in the range of 100μA).

[0046] When the feedback resistor is R5 (90KΩ), the gain is 100 times, which is suitable for medium IR current (10μA level).

[0047] When the feedback resistor is R6 (900KΩ), the gain is 1000 times, which is suitable for extremely small IR currents (on the order of 1μA).

[0048] The discrimination module consists of a Zener diode (8.4V) and a voltage detection circuit. The output of the operational amplifier is connected to the anode of the Zener diode, and the cathode of the Zener diode is grounded. When the signal voltage after amplification by the operational amplifier is lower than 8.4V, the Zener diode is in the cutoff state, the LED does not conduct, indicating that the TVS leakage current is within the normal range; when the signal voltage exceeds 8.4V, the Zener diode conducts and provides current to the indicator and alarm module.

[0049] The indicator alarm module consists of a current-limiting resistor R7 (1KΩ) and an LED indicator. R7 limits the current flowing through the LED to ensure normal LED illumination. When the operational amplifier output voltage is higher than the Zener diode's voltage regulation value, the LED turns on, indicating that the leakage current of the TVS diode has exceeded the set range and the TVS device needs to be replaced.

[0050] The circuit operation is as follows: The leakage current (IR) of the TVS diode flows through the sampling resistor R1 to generate a sampling voltage. When the leakage current (IR) of the TVS diode under test flows through the sampling resistor R1 (10KΩ), according to Ohm's law V = IR, a sampling voltage V proportional to IR will be generated across R1. 取样 =IR×R1, and since the leakage current of the TVS diode is usually very small and the sampling voltage is also low, subsequent signal amplification processing is required. Sampling voltage V 取样 The signal is further amplified by connecting the non-inverting input (+) of the operational amplifier. The non-inverting input (-) of the op-amp is connected to a voltage divider network consisting of R2 (1KΩ) and R3 (1KΩ). The voltage at this divider point is approximately half the supply voltage, used to set the reference potential and ensure that the amplifier circuit operates within a suitable range. The feedback resistors R4 (10KΩ), R5 (90KΩ), and R6 (900KΩ) determine the amplification factor, which can be set to 10x, 100x, or 1000x to meet different leakage current testing requirements.

[0051] The output voltage V of the op-amp out After magnification, the formula is followed: R feedback R4, R5, or R6 can be selected to adjust the gain. The amplified signal is then output by the operational amplifier and compared to the threshold value set by the Zener diode (8.4V). If V out If the voltage is below 8.4V, the Zener diode will not conduct and the LED will remain off, indicating that the leakage current of the TVS is normal.

[0052] If V out If the voltage is higher than 8.4V, the Zener diode will conduct, causing the LED indicator to light up. This indicates that the leakage current of the TVS diode has exceeded the set range, and further testing or replacement of the TVS diode is required.

[0053] Furthermore, R7 (1KΩ) serves as the current-limiting resistor for the LED, ensuring that the LED can light up normally when it is turned on without being damaged by overcurrent. When the LED lights up, it indicates that the IR of the TVS diode has exceeded the safe range, reminding the user that the TVS may have deteriorated or been damaged.

[0054] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0055] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A TVS diode leakage current fast detection circuit based on a self-resetting fuse, comprising a power supply module, a protection module, a sampling module, a signal amplification module, a detection module, and an indication and alarm module, characterized in that: The power module provides a stable DC power supply; The protection module consists of a resettable fuse and a TVS diode. The PPTC is connected in the power supply circuit, and the TVS diode is connected in parallel to the circuit under test.

2. The TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 1, characterized in that: The sampling module includes a sampling resistor R1, one end of which is connected to the TVS diode and the other end is grounded. It is used to detect the leakage current of the TVS diode and convert it into a small voltage signal.

3. The TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 1, characterized in that: The signal amplification module employs an operational amplifier, wherein: The non-inverting input terminal of the operational amplifier is connected to the upper end of the sampling resistor R1 to receive the sampled voltage signal; The non-inverting input of the op-amp is connected to a voltage divider network consisting of R2 and R3.

4. The TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 3, characterized in that: The gain of the operational amplifier is determined by the feedback resistors R4, R5, and R6, where: When R4 is selected, the gain is 10 times, which is suitable for leakage current in the range of 100μA. When R5 is selected, the gain is 100 times, which is suitable for leakage current in the range of 10μA; When R6 is selected, the gain is 1000 times, which is suitable for leakage current in the range of 1μA.

5. The TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 1, characterized in that: The discrimination module includes an 8.4V Zener diode and a voltage detection circuit, wherein: The output of the operational amplifier is connected to the anode of the Zener diode, and the cathode of the Zener diode is grounded. When the operational amplifier output voltage is below 8.4V, the Zener diode is in the off state; When the op-amp output voltage exceeds 8.4V, the Zener diode turns on, providing current to the indicator and alarm module.

6. The TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 1, characterized in that: The indicator alarm module includes a current-limiting resistor R7 and an LED indicator, wherein: R7 is used to limit the current flowing through the LED to ensure that the LED emits light normally; When the Zener diode is turned on, the LED lights up, indicating that the leakage current of the TVS diode has exceeded the set range.

7. A TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 3, characterized in that: The voltage divider network R2 and R3 provides a reference voltage that is half of the supply voltage.

8. A TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 5, characterized in that: The voltage relationship at the input terminals of the operational amplifier satisfies: The sampling voltage is generated by the leakage current of the TVS transistor flowing through the sampling resistor R1; The non-inverting input of the op-amp receives the sampled voltage and amplifies it according to the gain set by the feedback resistor; By adjusting the feedback resistor, it can be adapted to the leakage current detection requirements of different levels of TVS tubes.

9. A TVS diode leakage current fast detection circuit based on a self-resetting fuse according to claim 8, characterized in that: The function of the self-resetting fuse in the circuit is as follows: Limit current in case of overcurrent or short circuit to prevent circuit damage; It can automatically restore conduction after the fault is cleared, ensuring that the circuit works normally without the need for manual replacement of the fuse.

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