A switch current isolation detection circuit

Abstract

The utility model relates to the technical field of switch current detection, especially a kind of switch current isolation detection circuit, it includes detection unit, opto-coupler U3 and MCU processing unit, detection unit includes current detection chip U1 and detection resistance, the both ends of detection resistance are connected with the third pin and the fourth pin of current detection chip U1 respectively, the first pin of current detection chip U1 is connected with the first pin of opto-coupler U3, current-limiting resistance R11 has voltage dividing resistance R13 in parallel connection.This utility model is suitable for the detection of large current circuit, without the level pressure difference disadvantage of low-end detection;Realize electrical isolation, improve system safety and anti-interference ability, multiple detection resistances are designed in parallel, not only reduce single-point failure risk, also improve power bearing capacity and heat dissipation performance, suitable for large current occasion;Prevent overvoltage damage;Convenient for real-time current monitoring.

Description

Technical Field

[0001] This utility model relates to the field of switch current detection technology, and in particular to a switch current isolation detection circuit. Background Technology

[0002] Currently, there are many types of switches on the market, but most ordinary switches lack current detection functionality, or if they do, it's not isolated. Current detection can lead to many protection functions, such as timely alarms for overcurrent or current exceeding a certain limit, preventing equipment burnout due to overheating of components caused by excessive current. Therefore, current detection is essential for high-power switches. Current current detection methods involve adding a sensing resistor to the negative terminal of the current loop. The change in voltage across the resistor after current flow indicates the actual current magnitude. However, this method has significant drawbacks. Adding a sensing resistor with a certain resistance at the negative terminal results in a large voltage drop across it when the current is too high, potentially affecting the normal operation of the switch. Furthermore, a difference in ground plane potential can render the switch inoperable, limiting its application to low-current detection. Summary of the Invention

[0003] This invention addresses the problems of existing technologies by providing a current isolation detection circuit for switches. Its ingenious design is suitable for detecting high-current circuits and avoids the drawbacks of low-end detection due to voltage differences. It achieves electrical isolation, improving system safety and anti-interference capabilities. The parallel design of multiple detection resistors not only reduces the risk of single-point failure but also improves power handling capacity and heat dissipation performance, making it suitable for high-current applications. A current-limiting resistor R11 and a voltage-dividing resistor R13 are set at the output of the optocoupler U3 to effectively limit the voltage of the input MCU pins, preventing overvoltage damage. It also facilitates real-time current monitoring.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This utility model provides a current isolation detection circuit for a switch, which includes a detection unit, an optocoupler U3, and an MCU processing unit. The detection unit includes a current detection chip U1 and a detection resistor. The two ends of the detection resistor are connected to the third and fourth pins of the current detection chip U1, respectively. The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3. The current detection chip U1 is used to compare and amplify the current signal and output it to the optocoupler U3 through the first pin of the current detection chip U1. The fourth pin of the optocoupler U3 is connected to the MCU processing unit through a current limiting resistor R11. A voltage divider resistor R13 is connected in parallel with the current limiting resistor R11. The MCU processing unit receives the processed electrical signal from the optocoupler U3 and detects its voltage value.

[0006] The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3 through resistor R6, and the second pin of the optocoupler U3 is grounded through resistor R12.

[0007] The detection resistors include detection resistors R2, R3, and R4, which are connected in parallel. The two ends of detection resistor R2 are connected to the third and fourth pins of the current detection chip U1, respectively. The two ends of detection resistor R3 are connected to the third and fourth pins of the current detection chip U1, respectively. The two ends of detection resistor R4 are connected to the third and fourth pins of the current detection chip U1, respectively.

[0008] The resistance values ​​of the detection resistors R2, R3, and R4 are all 0.082R.

[0009] The circuit for current isolation detection of the switch also includes a power supply unit, which includes a diode D1, a capacitor C6, a resistor R15, a resistor R16, and a resistor R17. The diode D1, capacitor C6, and resistor R17 are connected in parallel. After the external power supply is input, the current is limited by resistor R15, then passes through the parallel resistor R17, diode D1, and capacitor C6, and finally through resistor R16 to provide a 12V operating voltage to the current detection chip U1.

[0010] The beneficial effects of this utility model are:

[0011] This invention features a clever design suitable for detecting high-current circuits, avoiding the voltage difference drawbacks of low-end detection. Its simple design requires minimal space, reducing design space and saving costs. It offers good scalability, providing feedback to the MCU processing unit after detection, making it flexible in application and allowing for a wide range of derived protection functions. Furthermore, this invention achieves electrical isolation, improving system safety and anti-interference capabilities. The optocoupler U3 completely isolates the current detection side from the MCU processing side, preventing damage to the sensitive MCU processing unit from surges, noise, or fault voltages that may be introduced from the high-voltage side. It is particularly suitable for industrial or communication power supplies and other scenarios with high safety and EMC requirements.

[0012] This invention enhances the reliability and stability of the system. The parallel design of multiple detection resistors (R2, R3, R4) not only reduces the risk of single-point failure but also improves the power handling capacity and heat dissipation performance, making it suitable for high-current applications. The optocoupler U3 output terminal is equipped with a current-limiting resistor R11 and a voltage-dividing resistor R13, which effectively limits the voltage of the input MCU pins and prevents overvoltage damage.

[0013] The MCU processing unit only needs to read an analog voltage and combine it with known gain and resistance parameters to calculate the load current in real time, which facilitates real-time current monitoring.

[0014] This invention achieves safe, accurate, reliable, and low-cost current isolation detection through an architecture of "high-precision differential detection + opto-isolation + MCU intelligent processing". It effectively solves the problems of easy interference, lack of isolation, and low accuracy in traditional current detection, and is particularly suitable for power monitoring systems of switches with high requirements for electrical safety and signal integrity. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of a current isolation detection circuit for a switch according to the present invention. Detailed Implementation

[0016] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0017] A current isolation detection circuit for a switch, such as Figure 1 As shown, it includes a detection unit, an optocoupler U3, and an MCU processing unit. The detection unit includes a current detection chip U1 and a detection resistor. The two ends of the detection resistor are connected to the third and fourth pins of the current detection chip U1, respectively. The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3. The current detection chip U1 compares and amplifies the passing current signal and outputs it to the optocoupler U3 through its first pin. The fourth pin of the optocoupler U3 is connected to the MCU processing unit through a current-limiting resistor R11. A voltage divider resistor R13 is connected in parallel with the current-limiting resistor R11. The MCU processing unit receives the processed electrical signal from the optocoupler U3 and detects its voltage value. The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3 through a resistor R6, and the second pin of the optocoupler U3 is grounded through a resistor R12. The detection resistors include R2, R3, and R4, which are connected in parallel. The two ends of detection resistor R2 are connected to the third and fourth pins of the current detection chip U1, respectively. The two ends of detection resistors R3 and R4 are also connected to the third and fourth pins of the current detection chip U1, respectively. The resistance values ​​of detection resistors R2, R3, and R4 are all 0.082Ω.

[0018] In this embodiment of the application, the current detection chip U1 is model INA193; the MCU processing unit includes an MCU processing chip U2, model SH79F6441, wherein the fourth pin of the optocoupler U3 is transmitted to the twenty-fourth pin of the MCU processing chip U2 through the current limiting resistor R11.

[0019] Specifically, after power is input, the signal first passes through three sensing resistors R2, R3, and R4 connected in series with the positive terminal of the circuit. When the power supply starts, these three resistors create a voltage difference across them due to changes in the current flowing through them. The third and fourth pins of the current sensing chip U1 are connected to the two ends of these sensing resistors to detect the voltage difference. After detecting the voltage difference across resistors R2, R3, and R4, because the resistance of these resistors is relatively small, the signal is amplified by the current sensing chip U1 (maximum amplification factor 100x). The amplified signal is then output through the first pin (output pin) of the current sensing chip U1. After the signal is amplified internally by the first pin of the current sensing chip U1, it outputs an amplified signal. This signal passes through the current-limiting resistor R6, then to the first pin of the optocoupler U3, and finally to the second pin of the optocoupler U3. At this point, resistor R6, the first and second pins of the optocoupler U3, and resistor R12 are connected in series. When the output voltage of the first pin of the current sensing chip U1 changes, the optocoupler... The LED inside optocoupler U3 changes its luminous intensity according to the magnitude of the output signal, converting the output electrical signal into an optical signal. This optical signal is then converted back into an electrical signal via pins 3 and 4 of optocoupler U3 before being transmitted. Pin 4 of optocoupler U3 is connected to 3.3V, and the output voltage is divided by a current-limiting resistor R11 and a parallel voltage-dividing resistor R13 (this voltage division is to protect the I / O input voltage of MCU processing chip U2 from exceeding the maximum input voltage of the I / O port). The divided signal is directly connected to pin 24 of MCU processing chip U2 for processing. When MCU processing chip U2 receives the processed electrical signal from optocoupler U3, it detects the voltage magnitude and the resistance values ​​(this parameter is fixed; the resistance values ​​of detection resistors R2, R3, and R4 are all 0.082R). Using Ohm's law I = U / R, the current flowing through the positive terminal of the circuit can be directly calculated.

[0020] Specifically, this invention features an ingenious design suitable for detecting high-current circuits, avoiding the voltage difference drawbacks of low-end detection. Its simple design requires minimal space, reducing design space and saving costs. It offers good scalability, providing feedback to the MCU processing unit after detection, allowing for flexible application. This method can be extended to provide a wide range of protection functions (such as outputting an alarm signal when the current exceeds the limit). Furthermore, this invention achieves electrical isolation, improving system safety and anti-interference capabilities. The optocoupler U3 completely isolates the current detection side from the MCU processing side, preventing damage to the sensitive MCU processing unit from surges, noise, or fault voltages that may be introduced from the high-voltage side. It is particularly suitable for industrial or communication power supplies and other scenarios with high safety and EMC requirements.

[0021] This invention enhances system reliability and stability. The parallel design of multiple sensing resistors (R2, R3, R4) not only reduces the risk of single-point failure but also improves power handling capacity and heat dissipation performance, making it suitable for high-current applications. The optocoupler U3 output is equipped with a current-limiting resistor R11 and a voltage-dividing resistor R13, effectively limiting the voltage input to the MCU pins and preventing overvoltage damage (especially under abnormal operating conditions), conforming to the electrical specifications of the MCU I / O ports (such as 3.3V logic level).

[0022] The MCU processing unit only needs to read an analog voltage (pin 24) and combine it with known gain and resistance parameters to calculate the load current in real time, which facilitates real-time current monitoring.

[0023] This invention achieves safe, accurate, reliable, and low-cost current isolation detection through an architecture of "high-precision differential detection + opto-isolation + MCU intelligent processing". It effectively solves the problems of easy interference, lack of isolation, and low accuracy in traditional current detection, and is particularly suitable for power monitoring systems of switches with high requirements for electrical safety and signal integrity.

[0024] In this embodiment, the current isolation detection circuit for the switch further includes a power supply unit. The power supply unit includes a diode D1, a capacitor C6, resistors R15, R16, and R17. Diode D1, capacitor C6, and resistor R17 are connected in parallel. After external power is input, the current is limited by resistor R15, then passes through the parallel resistor R17, diode D1, and capacitor C6, and finally through resistor R16 to provide a 12V operating voltage to the current detection chip U1. Specifically, after power is input, the current is simultaneously limited by resistor R15, then passes through resistor R17, diode D1, and capacitor C6 in parallel before reaching the negative terminal of the power supply. At this point, diode D1 acts as a 12V Zener diode, and capacitor C6 acts as a filter capacitor to ensure a stable 12V output. This circuit primarily outputs a 12V voltage to provide a 12V operating voltage for the current detection chip U1.

[0025] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the present utility model without departing from the scope of the present utility model shall fall within the scope of the present utility model.

Claims

1. A current isolation detection circuit for a switch, characterized in that: The system includes a detection unit, an optocoupler U3, and an MCU processing unit. The detection unit includes a current detection chip U1 and a detection resistor. The two ends of the detection resistor are connected to the third and fourth pins of the current detection chip U1, respectively. The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3. The current detection chip U1 is used to compare and amplify the current signal and output it to the optocoupler U3 through the first pin of the current detection chip U1. The fourth pin of the optocoupler U3 is connected to the MCU processing unit through a current-limiting resistor R11. A voltage divider resistor R13 is connected in parallel with the current-limiting resistor R11. The MCU processing unit receives the processed electrical signal from the optocoupler U3 and detects its voltage value.

2. The current isolation detection circuit for a switch according to claim 1, characterized in that: The first pin of the current detection chip U1 is connected to the first pin of the optocoupler U3 through resistor R6, and the second pin of the optocoupler U3 is grounded through resistor R12.

3. The current isolation detection circuit for a switch according to claim 1, characterized in that: The detection resistors include detection resistors R2, R3, and R4, which are connected in parallel. The two ends of detection resistor R2 are connected to the third and fourth pins of the current detection chip U1, respectively. The two ends of detection resistor R3 are connected to the third and fourth pins of the current detection chip U1, respectively. The two ends of detection resistor R4 are connected to the third and fourth pins of the current detection chip U1, respectively.

4. The current isolation detection circuit for a switch according to claim 1, characterized in that: The resistance values ​​of the detection resistors R2, R3, and R4 are all 0.082R.

5. A current isolation detection circuit for a switch according to claim 1, characterized in that: The current isolation detection circuit for the switch also includes a power supply unit, which includes a diode D1, a capacitor C6, a resistor R15, a resistor R16, and a resistor R17. The diode D1, capacitor C6, and resistor R17 are connected in parallel. After the external power supply is input, the current is limited by resistor R15, then passes through the parallel resistor R17, diode D1, and capacitor C6, and finally through resistor R16 to provide a 12V operating voltage to the current detection chip U1.

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