Multi-threshold multi-delay overvoltage protection circuit
By constructing a circuit with multiple single-threshold single-delay circuit modules connected in parallel, the problems of high cost, slow response and complex failure in the existing technology are solved, realizing low-cost, high-response multi-threshold multi-delay overvoltage protection, which is suitable for civil aviation electronic equipment.
Patent Information
- Application Number
- CN202423204336.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-24
AI Technical Summary
Existing multi-threshold and multi-delay overvoltage protection circuits suffer from high cost, slow response speed, and complex failure modes, making it difficult to meet the needs of high-safety scenarios such as civil aviation.
Multiple single-threshold, single-delay circuit modules are connected in parallel. The circuit, composed of resistors, capacitors, diodes, and comparators, combined with combinational logic, generates fault flag signals, thus avoiding the use of microcontrollers and analog-to-digital converters and achieving multi-threshold, multi-delay protection.
It reduces circuit costs, improves response speed, simplifies failure modes, and is suitable for high-safety scenarios such as civil aviation electronic equipment.
Smart Images
Figure CN223625566U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of analog electronics technology, and in particular relates to an overvoltage protection circuit with multiple thresholds and multiple delays. Background Technology
[0002] Overvoltage protection circuits are widely used in electronic and electrical equipment. They monitor the potential of the protected point, output fault indicator signals, and ultimately trigger protection actions, playing a crucial role in improving the safety and reliability of equipment. However, to prevent equipment from erroneously triggering overvoltage protection under normal operating conditions and normal input surge voltages, thus interfering with the normal functioning of the equipment, overvoltage protection in high-safety and high-reliability equipment typically has time-delay characteristics. Particularly in the civil aviation field, overvoltage monitoring or protection circuits are required to have multiple voltage thresholds and multiple corresponding delays. Their design complexity and circuit scale exceed those of simple single-threshold, non-delay overvoltage protection circuits.
[0003] For overvoltage protection circuits with multiple thresholds and delays, the common method used in the industry is to condition, sample, and convert the voltage at the protected point to digital, and then input the sampled voltage value into a microcontroller. The microcontroller performs voltage comparison and delay logic and outputs a fault flag signal through I / O pins. Although this approach has the advantages of programmability and flexibility, it also has the following drawbacks: (1) The microcontroller and analog-to-digital converter are expensive and lack domestic alternatives; (2) The entire loop involves many conversion stages, and the failure modes of the circuit itself and the mixed-signal integrated circuit are complex; (3) Due to the limited main frequency of the microcontroller and the sampling-hold time of the analog-to-digital conversion, the response speed of the entire protection circuit is slow, making it difficult to handle millisecond-level delays and limiting its application scenarios. In addition, although dedicated adjustable timing chips exist, most of them are second-level timing chips, which are commonly used in home electronic products and are difficult to use in high-safety scenarios of avionics. Utility Model Content
[0004] Purpose of this utility model: To provide an overvoltage protection circuit with multiple thresholds and multiple delays, thereby improving reliability and reducing costs.
[0005] Technical solution:
[0006] A multi-threshold, multi-delay overvoltage protection circuit includes: multiple single-threshold, single-delay circuit modules, wherein the input terminals of the multiple single-threshold, single-delay circuit modules are connected in parallel, and the output terminals are combined through a combination circuit to generate a fault flag signal. Each single-threshold, single-delay circuit module includes resistors R1, R2, R3, R4, and R5, capacitors C1 and C2, diode D1, comparator U1, and AND gate U2.
[0007] One end of resistor R1 is connected to the reference voltage, and the other end of resistor R1 is connected to one input terminal of comparator U1.
[0008] One end of resistor R2 is connected to the monitored point, and the other end of resistor R2 is connected to one end of resistor R3, one end of capacitor C1, and the other input terminal of comparator U1.
[0009] The output of comparator U1 is connected to one end of resistor R4, the cathode of diode D1, and one input of AND gate U2.
[0010] The other end of resistor R4 is connected to one end of capacitor C2, one end of resistor R5, and the other input terminal of AND gate U2;
[0011] The other end of resistor R5 is connected to the positive terminal of diode D1; the output of AND gate U2 serves as the output of the single-threshold single-delay circuit module.
[0012] The other end of resistor R3, the other end of capacitor C1, and the other end of capacitor C2 are grounded.
[0013] Preferably, the combinational circuit is based on diodes or synthetic logic.
[0014] Preferably, when monitoring overvoltage, the other end of resistor R1 is connected to the inverting input of comparator U1.
[0015] Preferably, when performing overcurrent protection, a Hall current sensor is also included, and the output terminal of the Hall current sensor is used as the monitored point after the current passes through it.
[0016] Preferably, the temperature coefficient of capacitor C2 is less than or equal to 30 ppm / ℃, and the accuracy is 1%.
[0017] Preferably, when the voltage at the monitored point is equal to the overvoltage threshold, the voltage drop at the connection point of resistors R2 and R3 is equal to the reference voltage.
[0018] Preferably, the temperature coefficients of resistors R2 and R3 are less than 25 ppm / ℃, and the accuracy is 0.1%.
[0019] Beneficial effects:
[0020] 1) Low cost. The entire circuit can be implemented using passive components such as resistors, capacitors, and diodes, as well as simple chips such as comparators and logic gates. These components are low in cost and have sufficient domestic alternatives.
[0021] 2) Fast response speed. Since the circuit does not contain complex components such as microcontrollers and analog-to-digital converters, does not involve sampling-hold time, and is not limited by the sampling theorem, it can respond quickly.
[0022] 3) Simple failure mode. The failure modes of complex components such as microcontrollers and analog-to-digital converters are complex. This invention avoids this problem. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the circuit composition of this utility model.
[0024] Figure 2 This is a circuit diagram of Embodiment 1 of the present invention.
[0025] Figure 3 This is a circuit diagram of Embodiment 2 of the present invention. Detailed Implementation
[0026] A multi-threshold, multi-delay overvoltage protection circuit, the structure of which is as follows: Figure 1 As shown. The threshold comparison circuit S1 compares the voltage at the protected point (possibly after voltage division) with a reference voltage and outputs a digital quantity d. This digital quantity passes through the RC delay circuit S2 to generate a delayed analog quantity a. The protection delay is proportional to the RC time constant in S2. d and a are fed into the AND gate S4 to obtain the final fault flag. The charge discharge circuit S3 quickly discharges the capacitor charge in S2 when there is no overvoltage fault at the protected point, clearing the fault flag to zero. The entire circuit can be implemented using passive components such as resistors, capacitors, and diodes, and simple chips such as comparators and logic gates, without needing to include large-scale digital integrated circuits or mixed-signal integrated circuits such as microcontrollers or analog-to-digital converters.
[0027] For multi-threshold, multi-delay overvoltage protection, multiple such circuits (with potentially identical internal electronic component parameters) can be connected in parallel at the input and combined at the output through a combinational circuit to generate a single fault flag signal. A commonly used combinational circuit is based on diodes or synthesized logic. This type of combinational circuit does not require a large number of logic gate chips and is low in cost.
[0028] Example 1
[0029] like Figure 2 As shown, this utility model can be used to build a protection circuit for RTCA / DO-160 "Class A equipment normal voltage surge". The single-threshold single-delay circuit 101 is used to achieve the protection function of 47V / 5ms. In the single-threshold single-delay circuit, resistors R1 to R3, capacitor C1 and comparator U1 constitute the threshold comparator circuit S1, R4 and C2 constitute the RC delay circuit S2, R5 and D1 constitute the charge discharge circuit S3, and U2 is an AND gate S4.
[0030] The circuit topologies of single-threshold single-delay circuits 102 and 103 are the same as those of single-threshold single-delay circuit 101, but the resistor and capacitor values are different to achieve 40V / 40ms and 32.2V / 50ms protection functions. All single-threshold single-delay circuits 101 to 103 output their respective fault flags to the combinational circuit 104 or the integrated logic circuit.
[0031] The single-threshold single-delay circuit 104 implements OR logic through Dx1 to Dx3, and outputs the final fault flag after shaping by the buffer Ux. The single-threshold single-delay circuit 104 uses diodes and resistors to implement multi-input OR logic, which is less expensive than multiple logic gate chips.
[0032] Figure 2 The power supply is omitted, but this does not affect the user's understanding and use of this embodiment.
[0033] Example 2
[0034] like Figure 3 As shown, this invention can also provide overcurrent protection. The Hall current sensor UH converts the protected current value into a Hall voltage, which is then applied... Figure 2 The circuitry in the circuit can achieve multi-threshold and multi-delay current protection.
Claims
1. A multi-threshold, multi-delay overvoltage protection circuit, characterized in that, include: Multiple single-threshold single-delay circuit modules are configured, with their inputs connected in parallel. Their outputs are combined through a combination circuit to generate a single fault flag signal. Each single-threshold single-delay circuit module includes resistors R1, R2, R3, R4, and R5; capacitors C1 and C2; diode D1; comparator U1; and AND gate U2. One end of resistor R1 is connected to the reference voltage, and the other end of resistor R1 is connected to one input terminal of comparator U1. One end of resistor R2 is connected to the monitored point, and the other end of resistor R2 is connected to one end of resistor R3, one end of capacitor C1, and the other input terminal of comparator U1. The output of comparator U1 is connected to one end of resistor R4, the cathode of diode D1, and one input of AND gate U2. The other end of resistor R4 is connected to one end of capacitor C2, one end of resistor R5, and the other input terminal of AND gate U2; The other end of resistor R5 is connected to the positive terminal of diode D1; the output of AND gate U2 serves as the output of the single-threshold single-delay circuit module. The other end of resistor R3, the other end of capacitor C1, and the other end of capacitor C2 are grounded.
2. The overvoltage protection circuit according to claim 1, characterized in that, The combinational circuit is either diode-based or synthesized logic.
3. The overvoltage protection circuit according to claim 1, characterized in that, When monitoring for overvoltage, the other end of resistor R1 is connected to the inverting input of comparator U1.
4. The overvoltage protection circuit according to claim 1, characterized in that, When overcurrent protection is performed, a Hall current sensor is also included. After the current passes through the Hall current sensor, the output terminal of the Hall current sensor is used as the monitored point.
5. The overvoltage protection circuit according to claim 1, characterized in that, The temperature coefficient of capacitor C2 is less than or equal to 30ppm / ℃, and the accuracy is 1%.
6. The overvoltage protection circuit according to claim 1, characterized in that, When the voltage at the monitored point is equal to the overvoltage threshold, the voltage drop at the connection point of resistors R2 and R3 is equal to the reference voltage.
7. The overvoltage protection circuit according to claim 1, characterized in that, The temperature coefficients of resistors R2 and R3 are less than 25 ppm / ℃, and the accuracy is 0.1%.