Failure-safe super-strong overvoltage protector

Abstract

The invention discloses a failure-safe super-strong overvoltage protector, which relates to the field of electronic products and comprises a switching device and a clamping device. The switch device and the clamping device are packaged into a whole and are positioned in the shell; a lead is arranged in the shell, one end of the lead is connected with the combination of the switching device and the clamping device, the other end of the lead is connected with an electrode outside the shell, and the lead and a welding spot of the lead serve as a failure open circuit device of the overvoltage protector. According to the invention, the product is miniaturized and surface-mounted in size; the working voltage is high in electrical appliance performance, and the fault tolerance of the working voltage is high; the surge capacity is high; the residual voltage is low and the protection effect is good; the overvoltage protector is energy-saving and environment-friendly, namely, the electrical performance of the overvoltage protector is low in leakage current under high working voltage, small in temperature rise in a high-temperature environment, and high in reliability in long-term use; failure open circuit; the method has wide application requirements and a wide prospect which are suitable for the development trend of the electronic industry at present.

Description

Technical Field

[0001] The present invention relates to the field of electronic products, and in particular to a fail-safe ultra-strong overvoltage protector. Background Art

[0002] The development of electronic products is increasingly moving towards lightweighting, miniaturization, and automated production. This, coupled with the need for electrical safety, energy conservation, and environmental protection, places increasing demands on miniaturization, surface mount technology, high energy efficiency, energy conservation, environmental protection, and safety of circuit protection devices. To adapt to this trend in the electronics industry, a fail-safe, ultra-strong overvoltage protection device is needed.

[0003] The most common power supply protection method involves connecting a gas discharge tube (GDT) in series with a pin-mounted clamping device and a varistor. Alternatively, connecting a pin-mounted varistor in series with a switch's TSS (solid-state discharge tube) is also a common protection method in some applications where current capacity requirements are low. However, a characteristic of these methods is that the independent clamping devices are implemented by wiring them together on the PCB. Alternatively, the GDT (gas discharge tube) and varistor are soldered together. This discrete device approach provides circuit protection in a solution-based manner. While it offers high current capacity, it is typically bulky, resulting in high protection effectiveness, i.e., high residual voltage. Furthermore, selecting and matching specific discrete device models can be challenging for non-professional electronic design engineers. Furthermore, the large PCB footprint makes it difficult to manufacture as a surface-mount product. Alternatively, to improve protection effectiveness and reduce residual voltage, TVS chips (transient voltage suppressors) can be stacked to form a single product. While this approach allows for a relatively small size, it is difficult to manufacture products with high current capacity, and the price is high, making it difficult to meet widespread application requirements.

[0004] The basic characteristics of overvoltage devices indicate a proportional relationship between operating voltage and clamping voltage. The higher the allowable operating voltage, the higher the clamping voltage. Therefore, to reduce residual voltage and enhance protection effectiveness, a higher operating voltage cannot be tolerated, resulting in a very narrow operating voltage range. For example, in some markets, where the operating voltage is typically 220VAC, the grid voltage can sometimes reach as high as 440VAC. If the operating voltage of the protective device is set too low, it could trigger incorrectly and fail. Alternatively, if the operating voltage is set too high, the residual voltage will also be relatively high. Consequently, the back-end circuitry and components must withstand higher surge surges, increasing back-end wiring costs and often failing to achieve effective protection.

[0005] The common surge failure mode for overvoltage circuit protection devices is short circuit failure. This can lead to power failure in the protected equipment at best, and in worst, fire in the circuit or protective device due to prolonged high-voltage short circuits. This is the most unacceptable failure mode for circuit protection. To avoid this, the current common approach is to use an external current fuse or thermal fuse. When current flows for a long time, the circuit fuse melts and disconnects the circuit, preventing fire. Alternatively, a thermal fuse can be used to disconnect the circuit when the temperature rises above a certain level, ensuring the safety of the circuit or device. Further solutions exist, such as soldering a thermal fuse to the overvoltage device. This reduces size and, when the overvoltage device overheats, the temperature is quickly transferred to the thermal fuse, immediately disconnecting the circuit. This approach is more compact and quicker than the first approach. However, these are only remedial measures for short circuits and cannot completely guarantee timely disconnection or fire prevention.

[0006] The current application circuits close to the present invention are as follows. These solutions are usually PCB board wiring modes, and there are also simple combination modes, but they only solve part of the problem, not all of the problems. They are now described as follows:

[0007] 1. Gas discharge tube GDT + metal oxide varistor MOV mode. Although this mode can be used to make products with low leakage current and high safe operating voltage, as well as high through-current products, this mode also has disadvantages: large size, high residual voltage, not easy to make into surface mount products, high failure risk. Depending on the coordination and selection of components, a thermal fuse is usually added to prevent the risk of fire, such as Figure 3 shown.

[0008] 2. The TVS stack design. While this design can produce products with relatively low clamping voltages, it also has disadvantages: it is bulky, difficult to manufacture as a surface-mount product, and generally lacks high-voltage, high-current products. Even if available, they are bulky, difficult to mass-produce, and expensive. This also leads to a short-circuit failure mode. Because TVS protection is designed for transient response, it is difficult to safely disconnect the circuit in the event of a high-energy surge, as is often the case with external current and temperature fuses.

[0009] Currently, no effective solutions have been proposed for the problems in related technologies. Summary of the Invention

[0010] In response to the problems in the related art, the present invention proposes a fail-safe ultra-strong overvoltage protector to overcome the above-mentioned technical problems existing in the existing related art.

[0011] To this end, the specific technical solutions adopted in the present invention are as follows:

[0012] A fail-safe, ultra-strong overvoltage protector comprising:

[0013] A switching device and a clamping device; the switching device and the clamping device are encapsulated as one body and located inside the shell; a lead is provided inside the shell, one end of the lead is connected to the combination of the switching device and the clamping device, and the other end of the lead is connected to the external electrode of the overvoltage protector.

[0014] Furthermore, the switching device is a switching device such as a solid discharge tube chip, and the clamping device is a clamping device such as a metal oxide varistor chip.

[0015] Furthermore, the clamping device and the switching device are connected in series.

[0016] Furthermore, the breakdown voltage of the protector is determined by the sum of the breakdown voltages of the clamping device and the switching device; the main voltage of the clamping voltage is represented by the clamping voltage of the clamping device 2.

[0017] Furthermore, packaging the switch device and the clamp device into one body includes:

[0018] The switching device and the clamping device are combined in series.

[0019] Furthermore, when a large surge voltage occurs due to overvoltage, the solder joint where the lead is connected to the overvoltage protector is selected as the breakpoint of surge failure.

[0020] Furthermore, when an overvoltage condition occurs, the lead is selected as a surge failure breakpoint.

[0021] Furthermore, the lead wire is a metal wire such as a copper wire, a silver wire, or a gold wire.

[0022] Furthermore, the current carrying capacity of the switch device and the clamping device is greater than the surge of the lead or the current carrying capacity of the solder joint.

[0023] Furthermore, the packaging methods include: standard packaging such as SMA packaging, SMB packaging, SMC packaging, 3025 packaging and 4032 packaging, or any packaging size based on the internal chip size.

[0024] The beneficial effects of the present invention are:

[0025] (1) Miniaturization and SMD-based design. Electrical performance: high operating voltage, high fault tolerance; strong surge capability; low residual voltage, good protection effect. Energy saving and environmental protection, that is, the electrical performance of the overvoltage protection device: low leakage current at high operating voltage, low temperature rise in high temperature environment, and high reliability for long-term use. Failure open circuit. Because of the above characteristics, the present invention has a wide range of application needs and broad prospects that adapt to the current development trend of the electronics industry.

[0026] (2) The product of the present invention can easily achieve the effect of ultra-low leakage current under high operating voltage, so the standby power consumption is very low, and the long-term working stability and temperature rise of the device are also very low, which is very consistent with the characteristics of energy saving, environmental protection and high long-term reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 2 is a schematic structural diagram of a fail-safe ultra-strong overvoltage protector according to an embodiment of the present invention;

[0029] Figure 2 This is a dimensional diagram of a solution of a fail-safe ultra-strong overvoltage protector according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the traditional solution of gas discharge tube GDT + varistor MOV mode;

[0031] Figure 4 This is a commonly used power protection scheme diagram;

[0032] Figure 5 This is one of the protection methods for small current failure.

[0033] Figure 6 This is the second diagram of the protection method for small current failure;

[0034] Figure 7 This is the basic data chart of the CMSLD551P102 product;

[0035] Figure 8 This is the electrical performance parameter diagram of the CMSLD551P102 product;

[0036] Figure 9 It is a regular test data graph;

[0037] Figure 10 It is the surge test data and failure mode diagram;

[0038] Figure 11 This is one of the temperature rise test data graphs;

[0039] Figure 12 This is the second temperature rise test data graph;

[0040] Figure 13 This is the wet heat load test data diagram;

[0041] Figure 14 This is a high temperature load test data graph;

[0042] Figure 15 This is a circuit diagram of a type of CMLS product used in BMS applications.

[0043] In the picture:

[0044] 1. Switching device; 2. Clamping device; 3. Housing; 4. Leads. DETAILED DESCRIPTION

[0045] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. By referring to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0046] According to an embodiment of the present invention, a fail-safe ultra-strong overvoltage protector is provided.

[0047] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. Figure 1-Figure 2 As shown, the fail-safe ultra-strong overvoltage protector according to an embodiment of the present invention includes:

[0048] A switching device 1 and a clamping device 2; the switching device 1 and the clamping device 2 are encapsulated as one body and located inside a housing 3; a lead 4 is provided inside the housing 3, one end of the lead 4 is connected to the combination of the switching device 1 and the clamping device 2, and the other end of the lead 4 is connected to the external electrode of the overvoltage protector.

[0049] In one embodiment, the switching device 1 is a switching device such as a solid state discharge tube TSS chip, and the clamping device 2 is a clamping device such as a metal oxide varistor MOV chip.

[0050] In one embodiment, the clamping device 2 and the switching device 1 are connected in series.

[0051] In one embodiment, the breakdown voltage of the ultra-strong overvoltage protector is characterized and determined by the sum of the breakdown voltages of the clamping device 2 and the switching device 1 ; and the main voltage of the clamping voltage is characterized by the clamping voltage of the clamping device 2 .

[0052] In one embodiment, packaging the switch device 1 and the clamp device 2 into one body includes:

[0053] The switch device 1 and the clamp device 2 are combined in series.

[0054] In one embodiment, when a large surge voltage occurs during overvoltage, the solder joint where the lead 4 is connected to the overvoltage protector is selected as the breaking point of the surge failure.

[0055] In one embodiment, when an overvoltage condition occurs, lead 4 is selected as a surge failure breakpoint.

[0056] In one embodiment, the lead 4 is a metal wire such as a copper wire, a silver wire, or a gold wire; the soldering point is a soldering point or a metal welding point.

[0057] In one embodiment, the current carrying capacity of the switch device 1 and the clamp device 2 is greater than the surge current carrying capacity of the lead 4 or the solder joint.

[0058] In one embodiment, the packaging method includes: standard packaging such as SMA packaging, SMB packaging, SMC packaging, 3025 packaging, and 4032 packaging, or any packaging size defined according to the internal chip size.

[0059] In order to facilitate understanding of the above technical solutions of the present invention, the working principle of the present invention in actual process is described in detail below.

[0060] The fundamental feature of this product is its combination of a clamping device and a switching device, ideal for applications such as power supply protection. This direct, integrated clamping and switching device package achieves high current flow rates and is thinner and lighter than existing multilayer TVS devices, offering higher current flow rates and lower residual voltage.

[0061] Because the present invention is a combination of a switching device and a clamping device, the working voltage of an overvoltage protector is the superposition of the breakdown voltages of the two devices, and the clamping voltage is basically characterized by the residual voltage of the clamping voltage of the clamping device, so there will be a relatively high working voltage and a relatively low residual voltage effect. The advantage of making a product in this way is that the allowable working voltage is high and the protection effect on the back-end circuit is greatly improved. For example, in a specific case designed by the present invention, the initial fast charging customer wanted to make a withstand voltage of 480V, and under a 500A surge impact, the residual voltage was less than 800V. The product made by stacking four TVS chips in series was more than 10mm in height and had a current capacity of only 300A, which could not meet the customer's size requirements. The device made with the idea of ​​the present invention is less than 5mm in height, and the current capacity doubled to 1000A, with a residual voltage of less than 800V. The cost is also greatly reduced, the reliability of long-term use is also greatly improved, and the protection effect is greatly improved. It is particularly suitable for applications such as small-sized fast charging and low-voltage electrical appliances.

[0062] The present invention also utilizes an electrical connection circuit to provide a fail-safe function. This disconnection occurs when an overvoltage condition is about to reach or exceed the protection limit of the overvoltage device, thereby preventing a short circuit. The failure point can be selected based on the lead extraction mechanism, either at the lead's solder joint to the overvoltage protector, or by using the lead itself as the surge failure disconnect point.

[0063] Taking leads as an example, current fuses actually use silver or copper wire to achieve overcurrent protection. Alternatively, when etching copper wire on a PCB, to ensure sufficient current flow, the length and thickness of the copper wire must be appropriately designed. This ensures that under normal operating conditions, the normal operating current can flow smoothly through the circuit without causing excessive current to fuse. The present invention reverses this copper wire flow, ensuring both normal operating current flow under normal operating conditions and timely disconnection under excessive surge conditions, preventing damage to overvoltage components and short circuit failure.

[0064] In new energy battery management systems (BMSs), lithium battery charging and discharging is typically performed using MOSFETs. However, different voltages can be used to power different battery strings. To minimize damage to the MOSFETs due to overshoot, high-power SMC-packaged TVS diodes, such as the 3kW SMCJ100CA TVS diode, are connected in parallel in the charging and discharging circuits. However, damage is a probabilistic event. For example, if one SMCJ100CA TVS diode is connected in parallel, the probability of damage is 5%. However, if two are connected in parallel, the probability of damage is reduced to 3%, and if six are connected in parallel, the probability of damage is reduced to 0.5%. Although more parallel connections improve safety, they cannot be completely avoided. If one TVS diode fails and short-circuits, all other TVS diodes become inoperable, rendering the entire circuit powerless. This can cause problems if an electric vehicle is parked outdoors. The present invention offers the advantages of a compact design and a form factor similar to that of a standard SMC solder pad, yet with a current flow capacity equivalent to that of six SMCJ100CA diodes, significantly reducing wiring space and costs. In addition, the product of the present invention has low residual voltage, which makes it convenient for customers to use MOS tubes from different manufacturers and easily matches circuits. In addition, it has a fail-open circuit, so even if the protection device is damaged, it will not affect the normal power supply of the battery pack.

[0065] The product of the present invention has the following features: a small package can achieve multiple excellent electrical properties; the electrically connected circuits can also have a fail-open effect.

[0066] This invention leverages the existing fail-open design concept to implement surge and temperature failure functions in the electrical connection circuit. This fail-safe approach is achieved by pre-designing the overvoltage device's current capacity to be greater than the current capacity of the electrical connection circuit. This prevents the circuit from failing before the overvoltage device, creating a fail-open effect. This differs from traditional fail-open protection in that traditional failure mode protection relies on an additional circuit open after failure, preventing the overvoltage device from failing without causing catastrophic consequences such as a chain reaction fire. This invention prevents this overvoltage protection device from failing and short-circuiting.

[0067] The construction idea of ​​the product of this invention: CMSL (Low Clamping Voltage CMS) is a further development of CMS, maintaining the characteristics of small size, large current and patch, significantly reducing the clamping voltage and enhancing the protection effect. Advantages of CMSL application:

[0068] This design provides ample operating voltage margin, enhancing safety and reliability while preventing long-term degradation of the varistor. It offers superior protection compared to traditional series-connected gas discharge tubes and varistors, as well as TVS stacks. It is fail-safe, effectively failing open-circuit under high-current surge conditions. High voltage and low leakage current also reduce the possibility of failure under low-current conditions. It is suitable for thin, compact applications and is well-suited for mass production.

[0069] like Figure 7 The following table shows the basic data of a product used for fast charging, such as CMSLD551P102. The dimensions of CMSLD551P102 are equivalent to the size of a semiconductor SMC package, with a thickness of less than 5mm. Dimensions refers to size, Inch refers to inches, and Millimeter refers to millimeters. Figure 8The following table shows the electrical performance parameters of the CMSLD551P102 product, including device ratings and specifications (ambient temperature = 25°C unless otherwise specified). The electrical performance data of the CMSLD551P102 is: it can withstand a 1000A 8 / 20us surge impact at a working voltage of 560V in a size equivalent to that of a semiconductor SMC. Under conditions of the same size, the current of a TVS is only tens of A. Parameter represents parameter, Nominal Varistor Voltage represents breakdown voltage, Maximum Allowable Continuous DC Voltage represents maximum allowable operating voltage, Maximum Leakage current represents maximum leakage current, Maximum Class Current represents maximum surge current, Operating Temperature Range represents operating temperature, and Storage Temperature represents storage temperature. Figure 9 As shown in the figure, some conventional test data are in line with the design parameters. Under the voltage of 550V, the leakage current is less than 5uA. Figure 10 As shown in the figure, the surge test data and failure mode are as follows: single current flow, under the combined wave surge impact of 1.2 / 50 & 8 / 20us, through 1KA impact, under the 1.5KV surge condition, the residual voltage is less than 720V. The failure mode of the extreme test is open circuit. Figure 11-12 As shown in the figure, it is a temperature rise test. In an environment with a normal temperature and a temperature of 80 degrees, the surface temperature of the product does not rise significantly when loaded with 400VAC and 48VAC. Figure 13 The following is the wet heat load test data, tested under double 85, 1000 hours, AC400V load conditions, the data is normal and passed the test. Figure 14 The data shown is a high-temperature load test data. First, the test is carried out at a high temperature of 150 degrees and a load of 400VAC for 168 hours. If the temperature is lowered to 125 degrees and the lightning strike is continued for 1000 hours, the data test is normal. The leakage current is slightly larger, but the voltage is normal. This situation is considered normal in the industry and passes the test.

[0070] The product of the present invention is suitable for miniaturization and high power requirements such as fast charging, as well as the demand for low standby power consumption. The current standby power consumption of general PD fast charging is 150mW, but the standby power consumption of PD fast charging of some companies has been reduced to 35mW. The present invention can well cooperate with the design of domestic PD to achieve the requirement of 35mW in standby power consumption.

[0071] The product of the present invention is also suitable for use in new energy battery management systems, and is used for CMLS products for MOS tube protection of charging and discharging circuits in BMS, and can replace high-power TVS. Figure 15 As shown in the figure, during the overshoot process, a high voltage exceeding the tolerance of the MOS tube will be added to both ends of the MOS tube. If no protection is performed, it will cause surge damage to the MOS. In addition, when CMS2 is added, when overvoltage occurs, CMS acts to clamp the voltage to a certain value to ensure the safety of the MOS.

[0072] Table 1 compares the surge and residual voltage data of high-power TVS and CMSL.

[0073] Test data shows that with the product of the present invention, one CMSL can replace many TVSs and provide a lower protection voltage. This not only reduces the number of TVSs used, reduces wiring space, and reduces costs, but also provides a safer protection effect, reduces the requirements for the surge resistance of the MOS tube, and makes the circuit cost lower and safer.

[0074] Table 1 Comparison of surge and residual voltage data of high-power TVS, CMS and CMSL

[0075]

[0076] In addition to the typical applications mentioned above, CMSL is also in demand in low-voltage electrical appliances, security, communications, automotive electronics, and new energy industries:

[0077] Low-voltage electrical appliances are used at 220VAC, are small in size, have high current flow, and low residual voltage, and are safe and reliable. Security communications require 48V power supply protection, and require a residual voltage less than 100V. They also require normal operation at an ambient temperature of 125 degrees Celsius, and also require open-circuit protection. Automotive electronic fast charging requires 800V-1000V-1200V-1500V, and the internal power supply also requires 12V-24V-48V. They also require a residual voltage less than 100V, and can operate normally at an ambient temperature of 125 degrees Celsius, and also require a fail-open circuit. New energy photovoltaic inverters have voltages ranging from 48V to 220V, and all require lower residual voltage and higher current flow, as well as a fail-open circuit effect, and all require CMSL.

[0078] To sum up, the product of the present invention is small in size, saving wiring space; it has high surge capacity and can withstand larger surge impacts; it has low clamping and better protection effect; it has good high-temperature performance, and at an ambient temperature of 125 degrees, all indicators meet the design standards of the specification; it is energy-saving and environmentally friendly, and meets the requirements of low standby power consumption such as fast charging, that is, the standby power consumption is reduced from 350mW to 80mW; it fails open circuit and is safe to use.

[0079] In the present invention, unless otherwise clearly stipulated and limited, the terms "install", "set", "connect", "fix", "screw" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fail-safe super-strong overvoltage protector, characterized in that: include: A switching device (1) and a clamping device (2); The switch device (1) and the clamp device (2) are encapsulated as a whole and located inside a housing (3); A lead wire (4) is provided inside the housing (3), one end of the lead wire (4) is connected to the combination of the switching device (1) and the clamping device (2), and the other end of the lead wire (4) is connected to the external electrode of the overvoltage protector.

2. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The switching device (1) comprises a solid discharge tube chip, and the clamping device (2) comprises a metal oxide varistor chip.

3. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The clamping device (2) and the switching device (1) are connected in series.

4. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The breakdown voltage of the overvoltage protector is determined by the sum of the clamping voltage (2) and the breakdown voltage of the switching device (1), and the main voltage of the clamping voltage is characterized by the clamping voltage of the clamping device (2).

5. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The step of packaging the switch device (1) and the clamp device (2) into one body comprises: The switching device (1) and the clamping device (2) are combined in series.

6. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: When an overvoltage surge voltage occurs, the welding point where the lead (4) is connected to the overvoltage protector is selected as the breaking point of the surge failure.

7. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: When an overvoltage condition occurs, the lead (4) is selected as a surge failure breakpoint.

8. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The lead wire (4) is a metal wire, including a copper wire, a silver wire and a gold wire; the soldering point includes a soldering point and a metal welding soldering point.

9. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The current carrying capacity of the switching device (1) and the clamping device (2) is greater than the current carrying capacity of the lead (4) or the welding point.

10. The fail-safe super-strong overvoltage protector according to claim 1, characterized in that: The size of the package is any package size defined according to the size of the internal chip, including: SMA package, SMB package, SMC package, 3025 package and 4032 package.

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