Detection circuit for isolating ultra-large current
By combining a power input module, a sampling module, an optocoupler, and a microcontroller unit, the problems of excessive voltage difference and signal isolation in the ultra-high current detection of PoE switches in the prior art are solved, and safe and reliable high-end current detection is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- UNIPOE IOT TECH CO LTD
- Filing Date
- 2025-01-21
- Publication Date
- 2026-05-15
AI Technical Summary
When detecting ultra-high current in PoE switches, existing technologies have limitations. Low-end detection methods suffer from excessive voltage differential, leading to machine malfunctions, while high-end detection methods cannot effectively isolate the current detection signal.
The circuit employs a combination of a power input module, a sampling module, an optocoupler, and a microcontroller unit. High-side detection is performed by detecting the voltage drop across the resistor, and the optocoupler is used to achieve signal isolation, preventing excessive voltage differences and ensuring circuit safety and reliability.
It achieves safe and reliable detection of ultra-high current, avoids the problem of excessive voltage difference in low-end detection, and achieves effective signal isolation, ensuring the stability and reliability of the circuit.
Smart Images
Figure CN224247794U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of switches, specifically to a detection circuit for isolating ultra-high current. Background Technology
[0002] Currently, there are many PoE switches on the market, most of which have a power rating below 500W (output current of around 10A). PoE switches with a power rating above 500W are very rare. In some scenarios, it is necessary to detect the PoE input current. Currently, the mainstream methods for current detection in the industry are divided into two types. One is low-end detection, which involves setting a sensing resistor on the ground loop and then detecting the current in the ground loop. However, if the current is too large, even a small sensing resistor value will create a large voltage difference across the sensing resistor, which may cause abnormal machine startup or operation, or other problems. Therefore, low-end detection is only suitable for small current applications. The other type is high-end detection, which involves setting a sensing resistor at the positive terminal of the input and detecting the current by measuring the voltage drop across the sensing resistor. Utility Model Content
[0003] This application provides a detection circuit for isolating ultra-high current, which can realize the detection of POE input current.
[0004] This application provides a detection circuit for isolating ultra-high current, including a power input module, a sampling module, an optocoupler, and a microcontroller unit, wherein:
[0005] The power input module is used to provide input current, and a detection resistor is connected to the positive terminal of the power input module;
[0006] The sampling module is used to collect the voltage drop of the detection resistor and amplify it to obtain a sampling output. The output terminal of the sampling module is connected to the first pin of the optocoupler.
[0007] The second pin of the optocoupler is grounded, and the third pin is connected to the signal input pin of the microcontroller unit. The microcontroller unit is used to process the sampled output.
[0008] The fourth pin of the optocoupler is connected to a low-voltage power supply, which is used to power the optocoupler and the microcontroller unit.
[0009] The first and second pins are the positive and negative terminals of the light-emitting diode in the optocoupler, respectively, and the third and fourth pins are the emitter and collector of the phototransistor in the optocoupler, respectively.
[0010] In some embodiments, the positive terminal of the power input module is connected to one end of the sensing resistor, the negative terminal is grounded, a front-end sampling point is provided between the positive terminal of the power supply and the sensing resistor, and a back-end sampling point is provided at the end of the sensing resistor away from the positive terminal of the power supply.
[0011] In some embodiments, the power input module further includes a filtering unit, which includes at least one filtering electrolytic capacitor and at least one filtering capacitor. The positive terminal of the filtering electrolytic capacitor is connected between the positive terminal of the power supply and the sensing resistor, and the negative terminal is grounded. One end of the filtering capacitor is connected between the positive terminal of the power supply and the sensing resistor, and the other end is grounded.
[0012] In some embodiments, after the negative terminal of the power input module is grounded, it is connected back to the negative terminal of the power supply through at least one ferrite bead.
[0013] In some embodiments, the sampling module includes a high-side current chip, with a positive detection pin connected to the front-end sampling point and a negative detection pin connected to the back-end sampling point, for obtaining the voltage drop across the detection resistor; the power supply pin of the high-side current chip is connected to a VCC power supply module for supplying power to the high-side current chip, and the output pin is connected to the first pin of the optocoupler.
[0014] In some embodiments, the VCC power supply module includes a second resistor, a third resistor, a fourth resistor, a Zener diode, and a third filter capacitor. One end of the second resistor is connected to the positive terminal of the power supply, and the other end is connected to the fourth resistor. The other end of the fourth resistor is grounded. One end of the third resistor is connected between the second and fourth resistors, and the other end is connected to the power supply pin of the high-side current chip. The positive terminal of the Zener diode is grounded, and the negative terminal is connected between the second and fourth resistors. One end of the third filter capacitor is connected between the second and fourth resistors, and the other end is grounded.
[0015] In some embodiments, the power supply pin of the high-end current chip is also connected to a grounding capacitor.
[0016] In some embodiments, a fifth resistor and a seventh resistor are also included. The fifth resistor is connected in series between the third pin and the signal input pin of the microcontroller unit, and one end of the seventh resistor is connected between the fifth resistor and the signal input pin of the microcontroller unit, while the other end is grounded.
[0017] The technical solution of this application has at least the following advantages:
[0018] 1. By setting up a power input module, a sampling module, an optocoupler, and a microcontroller unit, and connecting a detection resistor to the positive terminal of the power input module, on the one hand, the sampling module collects and amplifies the voltage drop across the detection resistor, realizing high-side detection of the input current and avoiding the drawback of excessive voltage difference in low-side detection of large input current; on the other hand, the optocoupler between the sampling module and the microcontroller unit achieves isolation of the sampling output, ensuring safety and reliability. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of a detection circuit for isolating ultra-high current provided in an exemplary embodiment of this application;
[0021] Figure 2 This is a schematic diagram of a power input module in a detection circuit for isolating ultra-high current, provided in an exemplary embodiment of this application.
[0022] Figure 3 This is a schematic diagram of a sampling module in a detection circuit for isolating ultra-high current, provided by an exemplary embodiment of this application;
[0023] Figure 4 This is a schematic diagram of a VCC power supply module for embodying a detection circuit for isolating ultra-high current, provided in an exemplary embodiment of this application. Detailed Implementation
[0024] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0027] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0028] This application provides a detection circuit for isolating ultra-high current, referring to... Figures 1 to 4The system comprises a power input module, a sampling module, an optocoupler U1, and a microcontroller unit (MCU). The power input module provides the input current, and its positive terminal is connected to a sensing resistor R1. The input current passes through R1 and is then supplied to subsequent devices. This sensing resistor R1 can be a manganese copper wire resistor with a rated current of 20A, supporting a maximum power of 1100W. The sampling module acquires the voltage drop across the sensing resistor R1 and amplifies it to obtain a sampled output. The output of the sampling module is connected to pin 1 of the optocoupler U1. Pin 2 of the optocoupler U1 is grounded through a current-limiting resistor R6, and pin 3 is connected to the signal input pin of the MCU. The MCU processes the received sampled output. Pin 4 of the optocoupler U1 is connected to a low-voltage power supply VDDH, which powers both the optocoupler U1 and the MCU. For example, VDDH can be a 3.3V power supply. In this design, pin 1 and pin 2 are the positive and negative terminals of the LED in optocoupler U1, respectively, while pin 3 and pin 4 are the emitter and collector of the phototransistor in optocoupler U1, respectively. When the sampling output is input through pin 1, it passes through pin 1 and pin 2 in sequence, and then through the current-limiting resistor R6 to ground, causing the LED inside optocoupler U1 to emit light. This, in turn, turns on the emitter and collector of the phototransistor, i.e., pins 3 and 4, thus enabling optocoupler U1 to simultaneously achieve signal isolation and sampling output transmission.
[0029] Furthermore, refer to Figure 2 The switch's PoE power is input from power socket J1, forming the positive power terminal PSU_V+ of the power input module. The positive power terminal PSU_V+ is connected to one end of the sensing resistor R1, while the negative power terminal is grounded. A front-end sampling point SP1 is located between the positive power terminal PSU_V+ and the sensing resistor R1, and a back-end sampling point Vmain is located at the end of the sensing resistor R1 furthest from the positive power terminal PSU_V+.
[0030] Furthermore, the power input module also includes a filtering unit, which comprises at least one filter electrolytic capacitor and at least one filter capacitor connected in parallel between the positive and negative terminals of the power supply. (Refer to...) Figure 2 In this embodiment, the filtering unit includes a filtering electrolytic capacitor EC1 and two filtering capacitors C1 and C2. The positive terminal of the filtering electrolytic capacitor EC1 is connected between the positive terminal of the power supply PSU_V+ and the detection resistor R1, and the negative terminal is grounded. One end of the filtering capacitors C1 and C2 is connected between the positive terminal of the power supply PSU_V+ and the detection resistor R1, respectively, and the other end is grounded.
[0031] Furthermore, after grounding, the negative terminal of the power input module is connected back to the negative terminal PGND of the PoE power supply via at least one ferrite bead. (Refer to...) Figure 2 In this embodiment, six ferrite beads are provided, numbered L1 to L6. The ferrite beads can absorb noise returning from the ground loop, thus better protecting the circuit.
[0032] Furthermore, refer to Figure 3 The sampling module includes a high-side current chip U2. The power supply pin VCC of the high-side current chip U2 is connected to a VCC power supply module for powering the chip. The positive detection pin V+ of the high-side current chip U2 is connected to the front-end sampling point SP1, and the negative detection pin V- is connected to the back-end sampling point Vmain. By processing the data obtained from the positive and negative detection pins V+ and V-, the high-side current chip U2 can obtain the voltage drop across the detection resistor R1. The output pin OUT of the high-side current chip U2 is connected to the first pin 1 of the optocoupler U1, used to amplify the voltage drop and provide the sampled output obtained from the high-side current chip U2 to the optocoupler U1.
[0033] Furthermore, refer to Figure 3 and Figure 4 The VCC power supply module includes a second resistor R2, a third resistor R3, a fourth resistor R4, a Zener diode D1, and a third filter capacitor C3. One end of the second resistor R2 is connected to the positive terminal PSU_V+ of the power supply, and the other end is connected to the fourth resistor R4, the other end of which is grounded. One end of the third resistor R3 is connected between the second and fourth resistors R2 and R4, and the other end is connected to the VCC power supply pin of the high-side current chip U2. The positive terminal of the Zener diode D1 is grounded, and the negative terminal is connected between the second and fourth resistors R2 and R4. One end of the third filter capacitor C3 is connected between the second and fourth resistors R2 and R4, and the other end is grounded. The second resistor R2 limits the current in the circuit. The second resistor R2 and the fourth resistor R4 form a resistive voltage divider, and the Zener diode D1, located between them, stabilizes the voltage at the midpoint between R2 and R4 at a fixed value, meeting the operating requirements of the high-side current chip U2. The third filter capacitor C3 filters this fixed voltage.
[0034] Furthermore, the VCC pin of the high-end current chip U2 is also connected to a ground capacitor. (See reference...) Figure 3 In this embodiment of the application, the grounding capacitor includes a grounding capacitor C4 and a grounding capacitor C5 connected in parallel. One end of the grounding capacitor C4 and the grounding capacitor C5 are respectively connected to the power supply pin VCC of the high-side current chip U2, and the other end is grounded.
[0035] Furthermore, refer to Figure 1A fifth resistor R5 and a seventh resistor R7 are also provided between pin 3 of the optocoupler U1 and the microcontroller unit (MCU). Resistor R5 is connected in series between pin 3 and the signal input pin of the MCU. One end of resistor R7 is connected between resistor R5 and the signal input pin of the MCU, and the other end is grounded. Resistors R5 and R7 act as a voltage divider. After amplification by the high-side current chip U2, the sampled output voltage may exceed the maximum allowable voltage value of the MCU's signal receiving pin. Therefore, by setting resistors R5 and R7, this situation can be avoided, thus protecting the MCU.
[0036] This application provides a detection circuit for isolating ultra-high current. By setting up a power input module, a sampling module, an optocoupler U1, and a microcontroller unit (MCU), and connecting a detection resistor R1 to the positive terminal of the power input module, on the one hand, the sampling module collects and amplifies the voltage drop across the detection resistor R1, realizing high-side detection of the input current and avoiding the drawback of excessive voltage difference in low-side detection of large input current; on the other hand, the optocoupler U1 set between the sampling module and the MCU achieves isolation of the sampling output, ensuring safety and reliability.
[0037] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.
Claims
1. A detection circuit for isolating ultra-high current, characterized in that, It includes a power input module, a sampling module, an optocoupler, and a microcontroller unit, wherein: The power input module is used to provide input current, and the positive terminal of the power input module is connected to a detection resistor. The sampling module is used to collect the voltage drop of the detection resistor and amplify it to obtain a sampling output. The output terminal of the sampling module is connected to the first pin of the optocoupler. The second pin of the optocoupler is grounded, and the third pin is connected to the signal input pin of the microcontroller unit. The microcontroller unit is used to process the sampled output. The fourth pin of the optocoupler is connected to a low-voltage power supply, which is used to power the optocoupler and the microcontroller unit. The first and second pins are the positive and negative terminals of the light-emitting diode in the optocoupler, respectively, and the third and fourth pins are the emitter and collector of the phototransistor in the optocoupler, respectively.
2. The detection circuit for isolating ultra-high current according to claim 1, characterized in that, The positive terminal of the power input module is connected to one end of the detection resistor, and the negative terminal is grounded. A front-end sampling point is provided between the positive terminal of the power supply and the detection resistor, and a back-end sampling point is provided at the end of the detection resistor away from the positive terminal of the power supply.
3. The detection circuit for isolating ultra-high current according to claim 1, characterized in that, The power input module further includes a filtering unit, which includes at least one filtering electrolytic capacitor and at least one filtering capacitor. The positive terminal of the filtering electrolytic capacitor is connected between the positive terminal of the power supply and the sensing resistor, and the negative terminal is grounded. One end of the filtering capacitor is connected between the positive terminal of the power supply and the sensing resistor, and the other end is grounded.
4. The detection circuit for isolating ultra-high current according to claim 2, characterized in that, After the negative terminal of the power input module is grounded, it is connected back to the negative terminal of the POE power supply through at least one ferrite bead.
5. The detection circuit for isolating ultra-high current according to claim 2, characterized in that, The sampling module includes a high-side current chip. The positive detection pin of the high-side current chip is connected to the front-end sampling point, and the negative detection pin is connected to the back-end sampling point to obtain the voltage drop of the detection resistor. The power supply pin of the high-side current chip is connected to a VCC power supply module for powering the high-side current chip, and the output pin is connected to the first pin of the optocoupler.
6. The detection circuit for isolating ultra-high current according to claim 5, characterized in that, The VCC power supply module includes a second resistor, a third resistor, a fourth resistor, a Zener diode, and a third filter capacitor. One end of the second resistor is connected to the positive terminal of the power supply, and the other end is connected to the fourth resistor. The other end of the fourth resistor is grounded. One end of the third resistor is connected between the second and fourth resistors, and the other end is connected to the power supply pin of the high-side current chip. The positive terminal of the Zener diode is grounded, and the negative terminal is connected between the second and fourth resistors. One end of the third filter capacitor is connected between the second and fourth resistors, and the other end is grounded.
7. The detection circuit for isolating ultra-high current according to claim 6, characterized in that, The power supply pin of the high-end current chip is also connected to a grounding capacitor.
8. The detection circuit for isolating ultra-high current according to claim 1, characterized in that, It also includes a fifth resistor and a seventh resistor. The fifth resistor is connected in series between the third pin and the signal input pin of the microcontroller unit. One end of the seventh resistor is connected between the fifth resistor and the signal input pin of the microcontroller unit, and the other end is grounded.