POE power supply and adapter power supply switching circuit

Abstract

The utility model discloses a POE power supply and adapter power supply switching circuit, which comprises a POE power supply module, an adapter power supply module and a power supply switching module, the POE power supply module and the adapter power supply module are connected into the power supply switching module, the output end of the power supply switching module is connected with PD power receiving equipment, and the output end of the power supply switching module is connected with the adapter power supply module. The POE power supply module and the adapter power supply module are respectively grounded, the power supply switching module comprises a first switching unit, a second switching unit and a switch element, the first switching unit is connected with the adapter power supply module and the switch element, and the second switching unit is connected with the POE power supply module and the switch element. According to the utility model, two power supply modes can be supported, the application range of the PD power receiving equipment is increased, the application convenience is improved, and fault maintenance of the PD power receiving equipment is facilitated.

Description

Technical Field

[0001] This utility model relates to the field of Power over Ethernet (PoE) technology, and in particular to a PoE power supply and adapter power supply switching circuit. Background Technology

[0002] Power over Ethernet (PoE) is a technology that uses unused wire pairs or data pins in an Ethernet cable to transmit direct current (DC). A PoE system includes power sourcing equipment (PSEs) and powered devices (PDs). The PSE supplies power to Ethernet client devices and manages the entire PoE process. PSEs are typically installed in patch panels, housing Ethernet switches and using a midspan hub to power the LAN's twisted-pair cabling. PDs are the loads that receive power, i.e., the client devices in the PoE system, such as IP phones, network security cameras, access points (APs), PDAs, mobile phone chargers, and many other Ethernet devices.

[0003] DC power adapter power supply is a method that converts AC power into DC power by connecting the DC power adapter to the mains power (usually 220V AC power) and then charging the device. It is used to provide a stable DC power supply for various electronic devices.

[0004] Currently, there are various types of PD (Power Distribution) devices on the market, some of which are only compatible with PoE (Power over Ethernet) and others with DC power adapters. However, in practical applications, supporting only one power supply method may result in a narrow range of applicability for PD devices, poor ease of use, and the inability to switch to another power supply method to define the fault range when a PD device fails, which is not conducive to fault diagnosis and repair. Utility Model Content

[0005] The purpose of this utility model is to provide a POE power supply and adapter power supply switching circuit that can support two power supply methods, increase the applicability of PD power receiving devices, improve application convenience, and facilitate fault diagnosis and repair of PD power receiving devices.

[0006] To achieve the above objectives, this utility model provides a POE power supply and adapter power supply switching circuit, including a POE power supply module, an adapter power supply module, and a power supply switching module. The POE power supply module is configured to connect to a POE power supply device, the adapter power supply module is configured to connect to an adapter power supply device, and the output terminal of the power supply switching module is configured to connect to a PD power receiving device.

[0007] The POE power supply module includes a POE power output terminal and a POE power ground terminal, which are used to connect to the power supply switching module.

[0008] The adapter power supply module includes an adapter power supply positive output terminal and an adapter power supply negative output terminal. The adapter power supply negative output terminal is grounded. The adapter power supply positive output terminal and the adapter power supply negative output terminal are used to connect to the power supply switching module.

[0009] The power supply switching module includes a first switching unit, a second switching unit, and a switching element. The first switching unit is connected to the adapter power supply module and the switching element. The second switching unit is connected to the POE power supply module and the switching element. The switching element is located in the first circuit formed by the POE power supply module and the power supply switching module.

[0010] When the adapter power supply module is connected to the power supply switching module, the second circuit formed by the adapter power supply module and the power supply switching module is turned on, and the first switching unit is triggered to control the switching element to disconnect.

[0011] When only the POE power supply module is connected to the power supply switching module, the second switching unit controls the switching element to turn on, thereby turning on the first circuit.

[0012] Optionally, the first switching unit includes a first resistor and an optocoupler. The optocoupler includes a light-emitting diode (LED) and a phototransistor. The input terminal of the LED is connected to the positive output terminal of the adapter power supply through the first resistor. The output terminal of the LED is connected to the negative output terminal of the adapter power supply. The input terminal of the phototransistor is connected to the switching element. The output terminal of the phototransistor is connected to the PoE power supply ground terminal.

[0013] Optionally, the second switching unit includes a second resistor and a Zener diode. The first end of the second resistor is connected to the POE power output terminal, the second end of the second resistor is connected to the negative terminal of the Zener diode, the input terminal of the phototransistor, and the control terminal of the switching element, and the positive terminal of the Zener diode is connected to the POE power ground terminal.

[0014] Optionally, the switching element is an NMOS transistor, the gate of which is connected to the second terminal of the second resistor, the drain of which is connected to the POE power output terminal, and the source of which is connected to the POE power ground terminal.

[0015] Optionally, the power supply switching module includes a common line for the first circuit and the second circuit, a first branch line for the first circuit, and a second branch line for the second circuit. The input terminal of the common line is connected to the positive output terminal of the adapter power supply and the POE power supply output terminal. The output terminal of the common line is connected to the first branch line and the second branch line respectively. The first branch line is connected between the common line and the POE power supply ground terminal, and the second branch line is connected between the common line and the negative output terminal of the adapter power supply. The switching element is disposed on the first branch line.

[0016] Optionally, it further includes a first isolation diode and a second isolation diode, wherein the first isolation diode is disposed in the first branch line, the negative terminal of the first isolation diode is connected to the drain of the NMOS transistor, and the second isolation diode is disposed in the second branch line.

[0017] Optionally, the shared line includes a first branch and a second branch connected in parallel, wherein the first branch is provided with a first filter capacitor and the second branch is provided with a second filter capacitor.

[0018] Optionally, the adapter power supply module includes a DC socket, a DC adapter, and an LC filter unit. The DC adapter is connected to the DC socket, and the DC adapter is connected to the power supply switching module through the LC filter unit.

[0019] Optionally, the LC filter unit includes a first inductor, a second inductor, a third filter capacitor, and an anti-static diode. The first end of the first inductor is connected to the DC adapter, and the second end of the first inductor is connected to the positive output terminal of the adapter power supply. The first end of the second inductor is connected to the DC adapter, and the second end of the second inductor is connected to the positive output terminal of the adapter power supply. The two ends of the third filter capacitor are respectively connected to the positive output terminal of the adapter power supply and the negative output terminal of the adapter power supply. The anti-static diode is connected in parallel with the third filter capacitor.

[0020] Optionally, the POE power supply module further includes a fourth filter capacitor and a fifth filter capacitor, the two ends of the fourth filter capacitor and the two ends of the fifth filter capacitor being connected to the POE power output terminal and the POE power ground terminal, respectively.

[0021] In this embodiment of the utility model, the POE power supply and adapter power supply switching circuit includes a POE power supply module, an adapter power supply module, and a power supply switching module. The POE power supply module and the adapter power supply module are respectively connected to the power supply switching module. The output terminal of the power supply switching module is connected to the PD power receiving device. The first switching unit of the power supply switching module is connected to the adapter power supply module and the switching element, and the second switching unit is connected to the POE power supply module and the switching element. The switching element is located in the first circuit formed by the POE power supply module and the power supply switching module. When only the adapter-powered device is connected, the first switching unit is triggered, the switching element is disconnected, the first circuit is not connected, and the second circuit formed by the adapter power supply module and the power supply switching module is connected. The current from the positive output terminal of the adapter power supply flows back to the negative output terminal of the adapter power supply, and the PD receiving device allows the adapter-powered device to supply power. When only the PoE-powered device is connected, the second switching unit controls the switching element to connect, making the first circuit connected. The current from the PoE-powered device flows back to the PoE power supply ground terminal, and the PD receiving device allows the PoE-powered device to supply power. When both the PoE-powered device and the adapter-powered device are connected, the first switching unit is triggered to control the switching element to disconnect. Therefore, the current from the PoE power supply output terminal cannot flow back to the PoE power supply ground terminal, the first circuit is not connected, the current from the positive output terminal of the adapter power supply flows back to the negative output terminal of the adapter power supply, the second circuit is connected, and the PD receiving device allows the adapter-powered device to supply power. This utility model embodiment can support two power supply methods, increasing the applicability of the PD receiving device, improving application convenience, and facilitating fault diagnosis of the PD receiving device. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the POE power supply and adapter power supply switching circuit in an embodiment of this utility model. Detailed Implementation

[0023] To explain in detail the technical content, structural features, and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0024] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0025] Please see Figure 1This utility model discloses a POE power supply and adapter power supply switching circuit, including a POE power supply module 10, an adapter power supply module 20 and a power supply switching module 30. The POE power supply module 10 is configured to connect to a POE power supply device, the adapter power supply module 20 is configured to connect to an adapter power supply device, and the output terminal Vmain of the power supply switching module 30 is connected to a PD power receiving device.

[0026] The POE power supply module 10 includes a POE power output terminal POE+ and a POE power ground terminal GND_POE. The POE power output terminal POE+ and the POE power ground terminal GND_POE are used to connect to the power supply switching module 30. The POE power ground terminal GND_POE is grounded.

[0027] The adapter power supply module 20 includes an adapter power supply positive output terminal VCC+ and an adapter power supply negative output terminal VCC-. The adapter power supply negative output terminal VCC- is grounded. The adapter power supply positive output terminal VCC+ and the adapter power supply negative output terminal VCC- are used to connect to the power supply switching module 30.

[0028] The power supply switching module 30 includes a first switching unit 31, a second switching unit 32, and a switching element Q1. The first switching unit 31 is connected to the adapter power supply module 20 and the switching element Q1. The second switching unit 32 is connected to the POE power supply module 10 and the switching element Q1. The switching element Q1 is located in the first circuit 40 formed by the POE power supply module 10 and the power supply switching module 30.

[0029] When the adapter power supply module 20 is connected to the power supply switching module 30, the second circuit 50 formed by the adapter power supply module 20 and the power supply switching module 30 is turned on, and the first switching unit 31 is triggered to control the switching element Q1 to turn off. When only the POE power supply module 10 is connected to the power supply switching module 30, the second switching unit 32 controls the switching element Q1 to turn on, so that the first circuit 40 is turned on.

[0030] In this embodiment of the utility model, the POE power supply and adapter power supply switching circuit includes a POE power supply module 10, an adapter power supply module 20, and a power supply switching module 30. The POE power supply module 10 and the adapter power supply module 20 are respectively connected to the power supply switching module 30. The output terminal Vmain of the power supply switching module 30 is connected to the PD power receiving device. The POE power supply module 10 and the adapter power supply module 20 are respectively grounded. The first switching unit 31 of the power supply switching module 30 is connected to the adapter power supply module 20 and the switching element Q1. The second switching unit 32 is connected to the POE power supply module 10 and the switching element Q1. The switching element Q1 is located in the first circuit 40 formed by the POE power supply module 10 and the power supply switching module 30. When only the adapter-powered device is connected, the first switching unit 31 is triggered, the switching element Q1 is disconnected, the first circuit 40 is not conducting, and the second circuit 50 formed by the adapter power supply module 20 and the power supply switching module 30 is conducting. The current from the positive output terminal VCC+ of the adapter power supply flows back to the negative output terminal VCC- of the adapter power supply, and the PD receiving device allows the adapter-powered device to supply power. When only the POE-powered device is connected, the second switching unit 32 is turned on and controls the switching element Q1 to turn on, so that the first circuit 40 is conducting, and the current from the POE-powered device flows back to the POE-powered device. When the power supply ground terminal GND_POE is connected, the first circuit 40 is on, allowing the PD power receiving device to be powered by the POE power supply device. When both the POE power supply device and the adapter power supply device are connected simultaneously, the first switching unit 31 is triggered to disconnect the control switch element Q1. Therefore, the current at the POE power output terminal POE+ cannot flow back to the POE power ground terminal GND_POE, the first circuit 40 is not on, and the current at the adapter power supply positive output terminal VCC+ flows back to the adapter power supply negative output terminal VCC-. The second circuit 50 is on, allowing the PD power receiving device to be powered by the adapter power supply device. This embodiment of the utility model can support two power supply methods, increasing the applicability of the PD power receiving device, improving application convenience, and facilitating fault diagnosis of the PD power receiving device.

[0031] In some embodiments, the first switching unit 31 includes a first resistor RP1 and an optocoupler U2. The optocoupler U2 includes a light-emitting diode (LED) and a phototransistor. The input terminal of the LED is connected to the positive output terminal VCC+ of the adapter power supply through the first resistor RP1, and the output terminal of the LED is connected to the negative output terminal VCC- of the adapter power supply. The input terminal of the phototransistor is connected to a switching element Q1, and the output terminal of the phototransistor is connected to the PoE power ground terminal GND_POE. When the adapter power supply module 20 is connected, the LED emits light, thereby controlling the conduction of its internal phototransistor. When the phototransistor is conducting, the voltage Vce across it is 0.

[0032] Specifically, the second switching unit 32 includes a second resistor RP2 and a Zener diode D3. The first end of the second resistor RP2 is connected to the POE power output terminal POE+, and the second end of the second resistor RP2 is connected to the negative terminal of the Zener diode D3, the input terminal of the phototransistor, and the control terminal of the switching element Q1. The positive terminal of the Zener diode D3 is connected to the POE power ground terminal GND_POE.

[0033] In some embodiments, the switching element Q1 is an NMOS transistor, the gate of which is connected to the second terminal of the second resistor RP2, the drain of which is connected to the POE power output terminal POE+, and the source of which is connected to the POE power ground terminal GND_POE.

[0034] It is understandable that the gate of an NMOS transistor is the control terminal, the drain is the input terminal, and the source is the output terminal. Since Vce = 0 when the phototransistor is on, the voltage connected to the gate of the NMOS transistor is 0. Because it is at the source, the Vgs (gate-source voltage) of the NMOS transistor Q1 is less than Vgsth (threshold voltage). That is, the voltage between the control terminal and the output terminal of the NMOS transistor is less than the threshold voltage, therefore the NMOS transistor does not conduct.

[0035] In some embodiments, the power supply switching module includes a common line 60 for the first circuit 40 and the second circuit 50, a first branch line 41 of the first circuit 40 and a second branch line 51 of the second circuit 50. The input terminal of the common line 60 is connected to the positive output terminal VCC+ of the adapter power supply and the POE power supply output terminal POE+. The output terminal of the common line 60 is connected to the first branch line 41 and the second branch line 51 respectively. The first branch line 41 is connected between the common line 60 and the POE power supply ground terminal GND_POE. The second branch line 51 is connected between the common line 60 and the negative output terminal VCC- of the adapter power supply. The switching element Q1 is disposed on the first branch line 41.

[0036] Specifically, the PoE power supply and adapter dual power supply switching circuit also includes a first isolation diode D4 and a second isolation diode. The first isolation diode D4 is located in the first branch line 41, and its cathode is connected to the drain of the NMOS transistor. The second isolation diode D5 is located in the second branch line 51. The isolation diodes are used to isolate the ground of the PD receiving device from the ground of the power supply. In addition, the isolation diodes can prevent interference between the two power supply circuits. The first isolation diode D4 and the second isolation diode D5 are model SMD-D3A. Of course, this utility model does not limit the model of the first isolation diode D4 and the second isolation diode D5.

[0037] Specifically, the common line 60 includes a first branch 61 and a second branch 62 connected in parallel. The first branch 61 is equipped with a first filter capacitor C1, and the second branch 62 is equipped with a second filter capacitor C2. The first filter capacitor C1 is model EC-10-16, with a specification of 47uF and 100 / NC. The second filter capacitor C2 is model C0805, with a specification of 100nF / 100VX. Of course, this utility model does not impose any limitations on this aspect.

[0038] In some embodiments, the adapter power supply module 20 includes a DC socket J2, a DC adapter A2, and an LC filter unit 21. The DC adapter A2 is connected to the DC socket J2 and is connected to the power supply switching module 30 through the LC filter unit 21. The DC adapter A2 is connected to an external power supply device (typically 220V AC) through the DC socket J2 to convert AC power to DC power. By connecting the DC adapter A2 to the LC filter unit 21, power fluctuations and ripples can be reduced, providing a stable power output.

[0039] Specifically, the LC filter unit 21 includes a first inductor L1, a second inductor L2, a third filter capacitor C3, and an anti-static diode D6. The first terminal of the first inductor L1 is connected to the DC adapter A2, and the second terminal of the first inductor L1 is connected to the positive output terminal VCC+ of the adapter power supply. The first terminal of the second inductor L2 is connected to the DC adapter A2, and the second terminal of the second inductor L2 is connected to the positive output terminal VCC+ of the adapter power supply. The two terminals of the third filter capacitor C3 are connected to the positive output terminal VCC+ and the negative output terminal VCC- of the adapter power supply, respectively. The anti-static diode D6 is connected in parallel with the third filter capacitor C3. The filter circuit composed of the first inductor L1 and the third filter capacitor C3 can filter the PoE power supply equipment. The second inductor L2 can enhance the filtering effect and suppress interference. The anti-static diode D6 can prevent electrostatic damage and protect the adapter power supply equipment. In this specific example, the anti-static diode D6 is model SMAJ58A.

[0040] In some embodiments, the POE power supply module 10 further includes a fourth filter capacitor C4 and a fifth filter capacitor C5, with the two ends of the fourth filter capacitor C4 and the two ends of the fifth filter capacitor C5 respectively connected to the POE power output terminal POE+ and the POE power ground terminal GND_POE.

[0041] In the specific example, the fourth filter capacitor C4 and the second filter capacitor C2 are capacitors of the same model and specifications, and the fifth filter capacitor C5 and the third filter capacitor C3 are capacitors of the same model and specifications.

[0042] Reference Figure 1 As shown below, the PoE power supply and adapter power supply switching circuit in this example will be described in detail.

[0043] When only the adapter-powered device is connected, the DC adapter A2 is connected to the DC socket J2, which powers on the adapter power supply module 20. The current from the positive output terminal VCC+ of the adapter power supply flows back to the negative output terminal VCC- of the adapter power supply through the second isolation diode D5, forming a power supply circuit. The PD power receiving device allows the adapter-powered device to supply power.

[0044] When only a PoE-powered device is connected to the power supply switching module 30, the PoE-powered device connects to the PoE power supply module 10 via a network cable port. After being rectified and filtered by a front-end dual-bridge rectifier, the power enters the PoE power supply module 10 to supply power to the PD receiving device. The second resistor RP2 and the Zener diode D3 form a clamping circuit with the gate of the NMOS transistor, connected to the output terminal of the power supply switching module 30. At this time, the Vgs (gate-source voltage) of the NMOS transistor is greater than Vgsth (threshold voltage), and the NMOS transistor is turned on. The current of the PoE-powered device flows back to the PoE power ground terminal GND_POE through the first isolation diode D4, forming a loop, and the PD receiving device allows the PoE-powered device to supply power.

[0045] When both the PoE power supply and the adapter power supply are connected simultaneously, the LED of optocoupler U2 emits light, and its phototransistor conducts after being exposed to light. Since the voltage across the phototransistor is Vce=0V, the gate voltage of the NMOS transistor is Vg=0V. At this time, the gate-source voltage Vgs of the NMOS transistor is less than the threshold voltage Vgsth, and the NMOS transistor does not conduct. Therefore, the PoE power supply cannot achieve power return and will not be able to supply power to the PD receiving device. However, the current of the adapter power supply can still achieve power return through the second isolation diode D5 connected to the second branch line 51. In this case, the PD receiving device will select the adapter power supply for power supply.

[0046] In summary, this utility model provides power through the adapter power supply when only the adapter power supply is available, and through the PoE power supply when only the PoE power supply is available. When both are available, the adapter power supply is preferred.

[0047] The above-disclosed examples are merely preferred embodiments of the present utility model, intended to facilitate understanding and implementation by those skilled in the art. They should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the scope of the present utility model patent shall still fall within the scope of the present utility model.

Claims

1. A PoE power supply and adapter power supply switching circuit, characterized in that, It includes a PoE power supply module, an adapter power supply module, and a power supply switching module. The PoE power supply module is configured to connect to a PoE power supply device, the adapter power supply module is configured to connect to an adapter power supply device, and the output terminal of the power supply switching module is configured to connect to a PD power receiving device. The POE power supply module includes a POE power output terminal and a POE power ground terminal, which are used to connect to the power supply switching module. The adapter power supply module includes an adapter power supply positive output terminal and an adapter power supply negative output terminal. The adapter power supply negative output terminal is grounded. The adapter power supply positive output terminal and the adapter power supply negative output terminal are used to connect to the power supply switching module. The power supply switching module includes a first switching unit, a second switching unit, and a switching element. The first switching unit is connected to the adapter power supply module and the switching element. The second switching unit is connected to the POE power supply module and the switching element. The switching element is located in the first circuit formed by the POE power supply module and the power supply switching module. When the adapter power supply module is connected to the power supply switching module, the second circuit formed by the adapter power supply module and the power supply switching module is turned on, and the first switching unit is triggered to control the switching element to disconnect. When only the POE power supply module is connected to the power supply switching module, the second switching unit controls the switching element to turn on, thereby turning on the first circuit.

2. The PoE power supply and adapter power supply switching circuit as described in claim 1, characterized in that, The first switching unit includes a first resistor and an optocoupler. The optocoupler includes a light-emitting diode (LED) and a phototransistor. The input terminal of the LED is connected to the positive output terminal of the adapter power supply through the first resistor. The output terminal of the LED is connected to the negative output terminal of the adapter power supply. The input terminal of the phototransistor is connected to the switching element. The output terminal of the phototransistor is connected to the PoE power supply ground terminal.

3. The PoE power supply and adapter power supply switching circuit as described in claim 2, characterized in that, The second switching unit includes a second resistor and a Zener diode. The first end of the second resistor is connected to the output terminal of the PoE power supply, and the second end of the second resistor is connected to the negative terminal of the Zener diode, the input terminal of the phototransistor, and the control terminal of the switching element. The positive terminal of the Zener diode is connected to the ground terminal of the PoE power supply.

4. The PoE power supply and adapter power supply switching circuit as described in claim 3, characterized in that, The switching element is an NMOS transistor. The gate of the NMOS transistor is connected to the second terminal of the second resistor, the drain of the NMOS transistor is connected to the POE power output terminal, and the source of the NMOS transistor is connected to the POE power ground terminal.

5. The PoE power supply and adapter power supply switching circuit as described in claim 4, characterized in that, The power supply switching module includes a common line for the first circuit and the second circuit, a first branch line for the first circuit, and a second branch line for the second circuit. The input terminal of the common line is connected to the positive output terminal of the adapter power supply and the POE power supply output terminal. The output terminal of the common line is connected to the first branch line and the second branch line respectively. The first branch line is connected between the common line and the POE power supply ground terminal, and the second branch line is connected between the common line and the negative output terminal of the adapter power supply. The switching element is disposed on the first branch line.

6. The PoE power supply and adapter power supply switching circuit as described in claim 5, characterized in that, It also includes a first isolation diode and a second isolation diode. The first isolation diode is disposed in the first branch line, and the negative terminal of the first isolation diode is connected to the drain of the NMOS transistor. The second isolation diode is disposed in the second branch line.

7. The PoE power supply and adapter power supply switching circuit as described in claim 5 or 6, characterized in that, The shared circuit includes a first branch and a second branch connected in parallel. The first branch is equipped with a first filter capacitor, and the second branch is equipped with a second filter capacitor.

8. The PoE power supply and adapter power supply switching circuit as described in claim 1, characterized in that, The adapter power supply module includes a DC socket, a DC adapter, and an LC filter unit. The DC adapter is connected to the DC socket, and the DC adapter is connected to the power supply switching module through the LC filter unit.

9. The PoE power supply and adapter power supply switching circuit as described in claim 8, characterized in that, The LC filter unit includes a first inductor, a second inductor, a third filter capacitor, and an anti-static diode. The first end of the first inductor is connected to the DC adapter, and the second end of the first inductor is connected to the positive output terminal of the adapter. The first end of the second inductor is connected to the DC adapter, and the second end of the second inductor is connected to the positive output terminal of the adapter. The two ends of the third filter capacitor are respectively connected to the positive output terminal and the negative output terminal of the adapter. The anti-static diode is connected in parallel with the third filter capacitor.

10. The PoE power supply and adapter power supply switching circuit as described in claim 1, characterized in that, The POE power supply module also includes a fourth filter capacitor and a fifth filter capacitor, with the two ends of the fourth filter capacitor and the two ends of the fifth filter capacitor respectively connected to the POE power output terminal and the POE power ground terminal.

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