Low-cost and high-response-speed overcurrent protection circuit

Abstract

The invention belongs to the technical field of over-current protection circuits, and particularly relates to a low-cost and high-response-speed over-current protection circuit which is characterized by comprising one of a DCDC circuit, a power amplifier circuit and a low-power-consumption circuit. The current-limiting resistor is connected between the power supply and the chip, and a current-limiting value is formed by setting the rated power and the resistance value of the current-limiting resistor. According to the over-current protection circuit, the current passing through the circuit is limited by adopting the current-limiting resistor, and the current is quickly responded and limited when the current is suddenly increased, so that a chip in the circuit is prevented from being damaged by over-current, and the use of the current-limiting resistor not only reduces the overall cost, but also improves the response speed and precision of over-current protection; therefore, the chip in the circuit is effectively protected, and circuit damage caused by overcurrent is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of overcurrent protection circuits, and particularly relates to a low-cost and high-response-speed overcurrent protection circuit. Background Art

[0002] In electronic devices, overcurrent protection is an important safety measure to prevent circuits from being damaged due to excessive current. In the prior art, common overcurrent protection devices include overcurrent protection chips and fuses. However, using overcurrent protection chips or fuses has certain limitations. When using an overcurrent protection chip for overcurrent protection, although precise current control can be achieved, its protection current range is small, making it difficult to meet the requirements of high-current applications. More importantly, the cost of overcurrent protection chips is relatively high, which limits their use in some cost-sensitive application scenarios. When using a fuse for overcurrent protection, the cost of the fuse is relatively low, but the response time of the fuse is generally 8 - 20S, resulting in a slow response speed. When an overcurrent situation occurs in the circuit, it takes a certain amount of time for the fuse to blow, and this delay may cause other components in the circuit to be damaged before the fuse blows. In addition, the protection accuracy of the fuse is not high, and it is difficult to achieve precise current control, which may lead to overprotection or underprotection situations, affecting the normal operation of the circuit.

[0003] The defects of these prior arts make electronic devices face problems such as poor overcurrent protection effect and difficult cost control. Therefore, developing an overcurrent protection solution that can ensure high response speed and precise protection while controlling costs has become an important topic in electronic circuit design. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of poor overcurrent protection effect and high cost in traditional overcurrent protection solutions, and provide a low-cost and high-response-speed overcurrent protection circuit.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions: A low-cost and high-response-speed overcurrent protection circuit, characterized by including one of a DCDC circuit, a power amplifier circuit, and a low-power circuit. A current-limiting resistor is provided in the overcurrent protection circuit, and the current-limiting resistor is connected between the power supply and the chip. By setting the rated power and resistance value of the current-limiting resistor to form a current-limiting value, the protection of the circuit is achieved.

[0006] In the above technical solution, the overcurrent protection circuit is one of the DCDC circuit, the power amplifier circuit, and the low-power circuit. Overcurrent protection is achieved by setting a current-limiting resistor between the power supply and the chip. The current-limiting resistor sets the rated power and resistance value according to the supply voltage and the requirements of the subsequent circuit operating voltage range. The rated power and resistance value constitute the current-limiting value. When the circuit is overcurrent, it will exceed the rated power of the current-limiting resistor, and the current-limiting resistor will burn out and be damaged instantly. The subsequent circuit will be disconnected, and the subsequent circuit will not be damaged, thus realizing the protection of the circuit. The overcurrent protection resistor can be returned to the factory for repair with the short-circuit function of the subsequent circuit being abnormal, without significantly increasing the maintenance cost.

[0007] The technical solution of the present invention adopts the method of using a current-limiting resistor. The function of the current-limiting resistor is to limit the current passing through the circuit. By selecting the rated power and resistance value to form the current-limiting value, it can quickly respond and limit the current when the current suddenly increases, thereby protecting the chip in the circuit from overcurrent damage. The response time of using a current-limiting resistor for overcurrent protection is at the ms or us level, and the price of the resistor is 0.2 - 2 cents. It solves the problems of high cost of overcurrent protection chips and slow response speed of fuses. The use of current-limiting resistors not only reduces the overall cost but also improves the response speed and accuracy of overcurrent protection, thus effectively protecting the chips in the circuit and avoiding circuit damage caused by overcurrent. The selection and configuration of the current-limiting resistor can be adjusted according to the requirements of different circuits to achieve the effect of low-cost and high-response-speed overcurrent protection. The present invention utilizes the power characteristics of the resistor and applies it to overcurrent protection of wide-voltage input circuits and high-voltage input circuits.

[0008] As a preferred solution of the present invention, the setting of the resistance value of the current-limiting resistor needs to consider the voltage drop and the ripple effect caused by adding the current-limiting resistor to the circuit. The resistance value of the current-limiting resistor cannot be randomly selected. Adding a current-limiting resistor to the circuit will cause a voltage drop and abnormal operation of the subsequent circuit. Among them, the ripple involves the acceptable range of the subsequent circuit and the dynamic current situation of the subsequent circuit.

[0009] As a preferred embodiment of the present invention, in the DCDC circuit, the power supply is a first DC power supply, the chip is a DC conversion chip, the positive electrode of the first DC power supply is connected to the current-limiting resistor R1, the other end of the current-limiting resistor R1 is connected to the input voltage interface of the DC conversion chip, one end of the second resistor R2 and the third resistor R3 in series is connected to the input voltage interface of the DC conversion chip, the other end of the series connection of the second resistor R2 and the third resistor R3 is grounded, and the DC conversion chip is grounded. The connection point between the second resistor R2 and the third resistor R3 is connected to the EN port of the DC conversion chip. In the DCDC circuit, the current-limiting resistor is connected between the first DC power supply and the DC conversion chip to provide effective overcurrent protection for the DC conversion chip. Among them, the current-limiting resistor R1 effectively controls the input current to prevent excessive current from entering the DC conversion chip. The series structure of the second resistor R2 and the third resistor R3 further stabilizes the input voltage to prevent the influence of voltage fluctuations on the DC conversion chip, and realizes the control of the DC conversion chip by connecting the EN port, quickly responds in the case of overcurrent, cuts off the power supply, protects the chip, thereby improving the response speed and accuracy of overcurrent protection.

[0010] As a preferred embodiment of the present invention, in the power amplifier circuit, the power supply is a second DC power supply, the chip is a power amplifier chip, the positive electrode of the first DC power supply is connected to the current-limiting resistor R1, and the other end of the current-limiting resistor R1 is connected to the input voltage interface of the power amplifier chip; one end of the fourth resistor R4 and the fifth resistor R5 in series is connected to the input voltage interface of the power amplifier chip, the other end of the series connection of the fourth resistor R4 and the fifth resistor R5 is grounded, and the power amplifier chip is grounded. The connection point between the fourth resistor R4 and the fifth resistor R5 is connected to the SD port of the power amplifier chip. In the power amplifier circuit, by connecting the current-limiting resistor R1 in series between the power supply and the power amplifier chip, the current flowing through the power amplifier chip is restricted to prevent damage to the power amplifier chip caused by overcurrent. The fourth resistor R4 and the fifth resistor R5 stabilize the working state of the power amplifier chip through series connection and grounding, and realize the control of overcurrent protection through the SD port, achieving effective protection of the power amplifier chip.

[0011] As a preferred embodiment of the present invention, the power amplifier chip is TPA3110D1 with an output power of 15W. By using a specific type of power amplifier chip and setting its output power, it is ensured that the circuit can be effectively protected in the case of overcurrent to avoid damage.

[0012] As a preferred embodiment of the present invention, the resistance value of the current-limiting resistor is less than 1Ω. For the DCDC circuit or the power amplifier circuit, a current-limiting resistor with a smaller resistance value can be selected to ensure the normal operation of the circuit. Preferably, the resistance value of the current-limiting resistor is 0.3 - 0.8Ω to further optimize the protection effect and response speed of the circuit.

[0013] As a preferred embodiment of the present invention, the packaging specification of the current-limiting resistor is 0805, 1206 or 1812 package. The size standard of the 0805 package is 2.0mm * 1.25mm * 0.5mm, that is, the length, width and height are 2 mm, 1.25 mm and 0.5 mm respectively. The size standard of the 1206 package is 3.2mm * 1.6mm * 0.5mm, and the size standard of the 1812 package is 4.5mm * 3.2mm. The above packaging forms have good heat dissipation performance and mechanical strength, ensuring the flexibility and compatibility of the circuit design. By selecting different packaging forms to meet the requirements of different circuit environments, it is ensured that the current-limiting resistor will not fail due to overheating during operation.

[0014] As a preferred embodiment of the present invention, in a low-power circuit, the current-limiting resistor is connected between the power supply and the chip, and the chip is HYM8563. In a low-power circuit, the current-limiting resistor is connected between the power supply and the HYM8563 chip. By selecting a suitable current-limiting resistor, the power consumption of the circuit can be effectively reduced.

[0015] As a preferred embodiment of the present invention, the resistance value of the current-limiting resistor is 400~1200Ω. For a low-power circuit, a current-limiting resistor with a larger resistance value can be selected to reduce power consumption. The resistance value range of the current-limiting resistor is 400~1200Ω. This range can provide effective overcurrent protection under different current conditions without significantly increasing the power consumption of the circuit.

[0016] As a preferred embodiment of the present invention, the packaging specification of the current-limiting resistor is 0603 or 0402. The size standard of the 0603 package is 1.6mm * 0.8mm, and the size standard of the 0402 package is 1.0mm * 0.5mm. This packaging form has the characteristics of small volume and convenient installation, and is suitable for low-power circuits with limited space.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present application provides an overcurrent protection circuit with low cost and high response speed, including one of the DCDC circuit, the power amplifier circuit, and the low-power circuit. A current-limiting resistor is provided in the overcurrent protection circuit, and the current-limiting resistor is connected between the power supply and the chip. The rated power and resistance value of the current-limiting resistor are set according to the supply voltage and the subsequent circuit operating voltage range requirements. The rated power and resistance value constitute the current-limiting value. By setting a current-limiting resistor between the power supply and the chip, overcurrent protection is achieved, which can reduce the cost of overcurrent protection and improve the response speed while ensuring the safety of the circuit, and has the advantages of low cost, fast response speed, and high protection accuracy.

[0018] 2. The overcurrent protection circuit of the present invention has a simple structure and low cost by reasonably designing the parameters and connection mode of the current-limiting resistor. Moreover, it can provide efficient overcurrent protection. The application of the current-limiting resistor in different circuits can be adjusted and optimized according to actual needs, so as to achieve the best protection effect, and has good applicability and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the DCDC circuit diagram in Embodiment 1 of the present invention; Figure 2 is the power amplifier circuit diagram in Embodiment 2 of the present invention; Figure 3 is the chip manual diagram of the TPA3110D1 chip in Embodiment 2 of the present invention; Figure 4 is the block diagram of the low-power RTC circuit in Embodiment 3 of the present invention; Figure 5 is the connection diagram of the low-power RTC circuit in Embodiment 3 of the present invention; Figure 6 is the chip manual diagram of the RTC chip HYM8563 in Embodiment 3 of the present invention; Figure 7 is the selection parameter table of the current-limiting resistor in Embodiment 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to more clearly describe the invention purpose, technical solution and technical effect advantages in the specific implementation cases of the present invention, the following will combine the specification drawings of the present invention to make a detailed description of the solutions in the specific embodiments. The specific technical solutions involved in the following specific embodiments are only for clearly and completely describing the innovative technical solutions of the present invention. They are only a part of the specific implementation schemes that the present invention can adopt, not all the embodiments, and should not be understood as a limitation to the innovative solutions of the present invention. Any solution adopting the same inventive concept of the present invention should be included in the protection scope of the present invention.

[0021] Secondly, the relevant descriptions of the drawings involved in the specific embodiments of the present invention are only for facilitating those skilled in the art to understand the solutions of the present invention. Some details shown in the drawings are for clearly presenting the technical solutions. It should not be considered that all the technical features in the drawings must be included in the specific implementation cases, and even less can the detailed features in the drawings be regarded as additional limitations to the innovative technical solutions of the present invention. The components in each embodiment described and shown in the drawings can be combined and arranged according to different configurations. These changes in the combined arrangements should be regarded as a part of all the embodiments of the innovative solutions of the present invention and included in the scope to be protected by the present invention.

[0022] Embodiment 1 This embodiment provides an overcurrent protection circuit with low cost and high response speed. A current-limiting resistor is arranged in the overcurrent protection circuit. The current-limiting resistor is connected between the power supply and the chip. By setting the rated power and resistance value of the current-limiting resistor to form a current-limiting value, the protection of the circuit is achieved.

[0023] Specifically, as Figure 1 shows the DCDC circuit diagram. In the DCDC circuit, the power supply is the first DC power supply (BAT1), and the chip is a DC conversion chip. The positive pole of the first DC power supply is connected to the current-limiting resistor R1. The other end of the current-limiting resistor R1 is connected to the input voltage interface (Vin) of the DC conversion chip. After the second resistor R2 and the third resistor R3 are connected in series, one end is connected to the input voltage interface of the DC conversion chip, and the other end of the series connection of the second resistor R2 and the third resistor R3 is grounded, and the DC conversion chip is grounded. The connection point between the second resistor R2 and the third resistor R3 is connected to the EN port of the DC conversion chip.

[0024] By setting the rated power and resistance value of the current-limiting resistor to form a current-limiting value, the protection of the circuit is achieved. The setting of the resistance value of the current-limiting resistor needs to consider the voltage drop and the ripple effect brought by adding the current-limiting resistor to the circuit. The resistance value of the current-limiting resistor cannot be randomly selected. Adding a current-limiting resistor to the circuit will cause a voltage drop and abnormal operation of the subsequent circuit. Among them, the ripple involves the acceptable range of the subsequent circuit and the dynamic current situation of the subsequent circuit. In this embodiment, the resistance value of the current-limiting resistor is less than 1Ω, and a current-limiting resistor with a smaller resistance value is selected to ensure the normal operation of the circuit.

[0025] The package specifications of the current-limiting resistor are 0805, 1206 or 1812. The 0805 and 1206 package specifications are different in size. The 0805 package is smaller and is suitable for circuit designs with limited space, while the 1206 package is larger and is suitable for circuits that require higher power handling capabilities. In addition, these two package specifications have high versatility and availability in the market, which is convenient for procurement and replacement. Specifically, when the circuit design needs to achieve efficient current-limiting protection in a limited space, the 0805 package can be selected; while in scenarios that require higher power handling capabilities, the 1206 package can be selected. The 1812 package can provide higher power handling capabilities and is suitable for high-voltage and large-current circuits, but its size is larger, which increases the circuit design difficulty and cost.

[0026] In the overcurrent protection circuit, if the subsequent circuit is short-circuited, it will cause a large overcurrent in the current-limiting resistor. The current-limiting resistor will be burned out instantaneously due to over-power with the subsequent short circuit, and the subsequent circuit will be disconnected, thus avoiding the burnout of the front-stage circuit and the scrapping of the PCB caused by continuous overcurrent. The current-limiting resistor can be returned to the factory for repair due to abnormal function with the subsequent circuit short circuit, and there is no obvious increase in maintenance costs.

[0027] Embodiment 2 Similar to Embodiment 1, this embodiment provides an overcurrent protection circuit with low cost and high response speed. The circuit of this embodiment is as Figure 2 shown in the power amplifier circuit diagram. In the input circuit of the power amplifier TPA3110D1, the power amplifier chip is TPA3110D1, which is an efficient Class-D audio power amplifier with a power of 15W. The positive pole (12V) of the first DC power supply (BAT1) is connected to the current-limiting resistor R1 with a resistance of 0.4Ω, a package of 1812, and a rated power of 0.75W. The other end of the current-limiting resistor R1 is connected to the input voltage interface (Vin: 8 - 26V) of the power amplifier chip. The fourth resistor R4 (300KΩ / 0402) and the fifth resistor R5 (100KΩ / 0402) are connected in series, one end of which is connected to the input voltage interface of the power amplifier chip, and the other end is grounded. Also, the power amplifier chip is grounded, and the connection point between the resistors R4 and R5 is connected to the SD port (2V) of the power amplifier chip.

[0028] The chip manual diagram of TPA3110D1 is as Figure 3 shown. When the input voltage is between 8V and 26V, the output power can reach 15W. Ignoring the efficiency issue, when the voltage of 12V is input, the rated current is 1.25A. The series current-limiting resistor is 0.4Ω with a rated power of 0.75W. When the current in the power amplifier circuit is at the rated current of 1.25A, the maximum voltage drop is 0.5V, and the power amplifier circuit works normally. When the power amplifier works abnormally and the current increases abnormally to 1.369A, reaching the rated power of the current-limiting resistor, the continuous large current will cause the current-limiting resistor to open-circuit and cannot be restored for protection, thus protecting the subsequent circuit. The overcurrent protection method of the current-limiting resistor belongs to the non-recoverable protection mechanism. However, from a design perspective, this situation only occurs when the subsequent stage is abnormally overloaded. Therefore, when this situation occurs, it should be returned to the factory for repair and troubleshooting in a timely manner. Compared with the self-recovery fuse, the response time is shorter, so that the subsequent circuit will not be damaged when the self-recovery fuse does not act; in terms of cost, it is much cheaper than the self-recovery fuse; from a design perspective, if there is a problem with the subsequent stage, necessary troubleshooting is required, and the normal circuit will not have abnormalities.

[0029] Embodiment 3 Similar to Embodiment 1, this embodiment provides an overcurrent protection circuit with low cost and high response speed. The circuit of this embodiment is as Figure 4 shown in the low-power consumption circuit diagram. The current-limiting resistor is connected between the power supply and the chip. The chip is HYM8563, and the other end of HYM8563 is grounded. According to the manual, when HYM8563 works normally, the working voltage is between 1.8V and 5.5V, and the maximum current when powered by a 3V battery and working normally does not exceed 1100nA, as Figure 5 shown. Since the battery is used for power supply in many working conditions of this circuit, and the battery power supply has safety hazards such as overcurrent, the traditional overcurrent safety protection measures do not have a good effect on protecting small currents.

[0030] In a low-power circuit, a 1KΩ / 0402 current-limiting resistor is connected in series on the power supply, with a rated power of 0.1W. When the circuit is working normally, the voltage drop is less than 1.1mV, meeting the working conditions of the subsequent circuit. When the abnormal current of the subsequent circuit increases to 10mA, the rated power of the resistor is reached, thereby protecting the circuit. During normal operation, the power consumption is extremely low at 1.21nW, and the current is small and negligible.

[0031] For those skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, they can refer to the conventional technical manuals in the art. At the same time, for the places where the above terms appear, they can make appropriate understandings or adjustments referentially. Without creative efforts, they can derive the implementation situations of the same or similar technical solutions.

[0032] The above embodiments only describe the basic principles, main features, and / or advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and the description in the invention content part of the specification are only the principles or specific cases of the present invention. Without departing from the essence of the innovative solutions of the present invention, there are various changes and improvements to the innovative solutions of the present invention, and these changes and improvements all fall within the scope of protection required by the present invention.

Claims

1. A low-cost, high-response speed overcurrent protection circuit, characterized in that: It comprises one of a DCDC circuit, a power amplifier circuit and a low power consumption circuit. A current limiting resistor is arranged in the overcurrent protection circuit. The current limiting resistor is connected between a power supply and a chip. The rated power and resistance value of the current limiting resistor are set to form a current limiting value, so as to realize circuit protection.

2. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 1, characterized in that: In the DCDC circuit, the power supply is a first DC power supply, the chip is a DC conversion chip, the positive electrode of the first DC power supply is connected to the current limiting resistor R1, the other end of the current limiting resistor R1 is connected to the input voltage interface of the DC conversion chip, one end of the second resistor R2 and the third resistor R3 connected in series is connected to the input voltage interface of the DC conversion chip, the other end of the second resistor R2 and the third resistor R3 connected in series is grounded, and the DC conversion chip is grounded, and the connection point between the second resistor R2 and the third resistor R3 is connected to the EN port of the DC conversion chip.

3. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 1, characterized in that: In the power amplifier circuit, the power supply is a second DC power supply, the chip is a power amplifier chip, the positive electrode of the first DC power supply is connected to the current limiting resistor R1, and the other end of the current limiting resistor R1 is connected to the input voltage interface of the power amplifier chip; one end of the fourth resistor R4 and the fifth resistor R5 connected in series is connected to the input voltage interface of the power amplifier chip, the other end of the fourth resistor R4 and the fifth resistor R5 connected in series is grounded, and the power amplifier chip is grounded, and the connection point between the fourth resistor R4 and the fifth resistor R5 is connected to the SD port of the power amplifier chip.

4. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 3, characterized in that: The power amplifier chip is TPA3110D1, and the output power is 15W.

5. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 2 or 3, characterized in that: The resistance value of the current limiting resistor is less than 1Ω.

6. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 5, characterized in that: The resistance value of the current limiting resistor is 0.3-0.8Ω.

7. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 5, characterized in that: The packaging specification of the current limiting resistor is 0805 or 1206.

8. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 1, characterized in that: In the low power consumption circuit, the current limiting resistor is connected between the power supply and the chip, and the chip is HYM8563.

9. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 8, characterized in that: The resistance value of the current limiting resistor is 400-1200Ω.

10. A low-cost, high-response speed overcurrent protection circuit as claimed in claim 8, characterized in that: The packaging specification of the current limiting resistor is 0603 or 0402.

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