Control circuit of power supply and POE power supply circuit

Abstract

The application provides a power supply control circuit and a POE power supply circuit. The power supply control circuit comprises a control unit, and the control unit comprises a first switching device, a second switching device, a first voltage dividing unit and a second voltage dividing unit. The control end of the first switching device is used for inputting a control signal. The second end of the first switching device is connected with the control end of the second switching device. The first end of the second switching device is connected between the first end of the first voltage dividing unit and a DC power supply end. The first end of the first voltage dividing unit is connected on a connection branch between the second switching device and a second input end of the control circuit. The working of the second switching device is controlled by the control signal. The working of the second switching device is indirectly controlled by the input control signal. The working of the second voltage dividing unit is controlled by controlling the second switching device. Since the second voltage dividing unit is in the working state, the power supply demand can be detected during the test of the power supply end, so that the power supply path can not be powered off.

Description

Technical Field

[0001] The present application relates to the field of power supply circuits, and in particular to a power supply control circuit and a POE power supply circuit. Background Art

[0002] With the continuous development of engineering applications, more and more products are equipped with multiple network ports for data transmission and use. The design of a single power port can easily cause users to plug it in incorrectly. In addition, some important equipment cannot be powered off during use, and the single power port design cannot meet this requirement.

[0003] Therefore, dual-port or even multi-port POE power supply circuits have become a power supply demand that needs to be solved urgently. The circuit is required to support dual-port or multi-port POE power supply and also to maintain power supply during use.

[0004] The above information disclosed in the background technology section is only used to enhance the understanding of the background technology of the technology described in this article. Therefore, the background technology may contain certain information that does not form the prior art known in this country to those skilled in the art. Summary of the Invention

[0005] The main purpose of the present application is to provide a power supply control circuit and a POE power supply circuit to solve the problem of easy power failure of the POE power supply circuit in the prior art.

[0006] According to one aspect of an embodiment of the present invention, a control circuit of a power supply is provided, including a control unit, the control unit including a first switching device, a second switching device, a first voltage dividing unit and a second voltage dividing unit, the control end of the first switching device is used to input a control signal, the first end of the first switching device is connected to the first input end of the control circuit, the second end of the first switching device is connected to the control end of the second switching device, the first end of the second switching device is connected between the first end of the first voltage dividing unit and the DC power supply end, the second end of the second switching device is connected to the first end of the second voltage dividing unit, the second end of the second voltage dividing unit is connected to the first end of the first switching device, the first end of the first voltage dividing unit is connected to a connecting branch between the second switching device and the second input end of the control circuit, the second end of the first voltage dividing unit is connected to a connecting branch between the second voltage dividing unit and the first switching device, and the operation of the second switching device is controlled by the control signal.

[0007] Optionally, the control circuit also includes a third switching device, a third voltage dividing unit and a fourth voltage dividing unit, the control end of the third switching device is connected to the first end of the third voltage dividing unit, the first end of the third switching device is connected to the second input end of the control circuit, the second end of the third switching device is connected to the DC power supply end, the second end of the third voltage dividing unit is connected between the first end of the third switching device and the second input end of the control circuit, the first end of the fourth voltage dividing unit is connected to the first end of the third voltage dividing unit, and the second end of the fourth voltage dividing unit is connected between the first input end of the control circuit and the ground end.

[0008] Optionally, the third switching device is a second PMOS tube, the gate of the second PMOS tube is the control end of the third switching device, the drain of the second PMOS tube is the first end of the third switching device, the source of the second PMOS tube is the second end of the third switching device, the third voltage dividing unit is at least one voltage dividing resistor, and the fourth voltage dividing unit includes a first voltage dividing sub-unit and a second voltage dividing sub-unit, the two ends of the first voltage dividing sub-unit are respectively connected to the first end of the third voltage dividing unit and the first end of the second voltage dividing sub-unit, and the second end of the second voltage dividing sub-unit is connected to the connecting branch between the fourth voltage dividing unit and the first end of the control circuit.

[0009] Optionally, the control circuit also includes: a fourth switching device, the control end of the fourth switching device is connected between the first voltage divider subunit and the second voltage divider subunit, the first end of the fourth switching device is connected to the second end of the second voltage divider subunit, and the second end of the fourth switching device is connected to the ground end.

[0010] Optionally, the control circuit further includes: a protection unit, the protection unit including a first diode, the cathode of the first diode is connected to the first input end of the control circuit, and the anode of the first diode is connected to the connection branch between the first switching device and the first voltage divider unit.

[0011] Optionally, the first switching device is a PNP transistor, the base of the PNP transistor is the control end of the first switching device, the emitter of the PNP transistor is the first end of the first switching device, the collector of the PNP transistor is the second end of the first switching device, the second switching device is a first PMOS tube, the gate of the first PMOS tube is the control end of the second switching device, the drain of the first PMOS tube is the first end of the second switching device, the source of the first PMOS tube is the second end of the second switching device, the first voltage dividing unit includes at least one voltage dividing resistor, and the second voltage dividing unit includes at least one voltage dividing resistor.

[0012] Optionally, the fourth switch device is an NMOS tube, the gate of the NMOS tube is the control terminal of the fourth switch device, the source of the NMOS tube is the first terminal of the fourth switch device, and the drain of the NMOS tube is the second terminal of the fourth switch device.

[0013] According to another aspect of an embodiment of the present invention, a POE power supply circuit is also provided, including: at least one power supply end; at least one network port, the power supply end is connected to the network port; at least one power receiving end is connected to the network port; at least one control circuit of any one type, the output end of the power receiving end is connected to the first input end and the second input end of the control circuit, and the two ends of the control circuit are respectively connected to the power receiving end and the DC power supply end; a conversion circuit, the first end of the conversion circuit is connected to the DC power supply end, the second end of the conversion circuit is connected to the ground end, and the conversion circuit is used to reduce the voltage output by the control circuit.

[0014] Optionally, the POE power supply circuit further includes: at least one second diode, the anode of the second diode is connected to the control circuit, and the cathode of the second diode is connected to the DC power supply terminal.

[0015] Optionally, the POE power supply circuit further includes: at least one rectifier circuit, wherein one rectifier circuit is connected between the network port and the power receiving end.

[0016] In an embodiment of the present invention, the control circuit of the power supply includes a first switching device, a second switching device, a first voltage dividing unit and a second voltage dividing unit. A control signal is input to the first switching device to control the working state of the first switching device. Since the first switching device is electrically connected to the second switching device, the control signal indirectly controls the operation of the second switching device. By controlling the working state of the second switching device, the operation of the second voltage dividing unit is controlled. In this way, when the circuit is applied to the POE power supply circuit, since the second voltage dividing unit is in the on state (working state), when the power supply end tests whether the circuit has a power supply demand, the power supply demand can be detected, so that the circuit can be controlled so that it does not lose power. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0018] Figure 1 shows a circuit diagram of a control unit according to an embodiment of the present application;

[0019] Figure 2 A circuit diagram showing a control circuit of a power supply according to an embodiment of the present application;

[0020] Figure 3 A circuit diagram of a POE power supply circuit according to an embodiment of the present application is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. First switching device; 11. Second switching device; 12. First voltage-dividing unit; 13. Second voltage-dividing unit; 14. Third switching device; 15. Third voltage-dividing unit; 16. Fourth voltage-dividing unit; 17. Fourth switching device; 18. First diode; 20. Network port; 21. Rectifier circuit; 22. Power receiving end; 23. Control circuit; 24. Second diode; 25. Conversion circuit. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element or intervening elements may be present. Moreover, in the specification and claims, when it is described that an element is "connected to" another element, the element may be "directly connected to" the other element or "connected to" the other element through a third element.

[0027] As mentioned in the background technology, the POE power supply circuit in the prior art has the problem of power failure. In order to solve the above problem, in a typical embodiment of the present application, a power supply control circuit and a POE power supply circuit are provided.

[0028] According to an embodiment of the present application, a control circuit of a power supply is provided.

[0029] Figure 1 FIG is a circuit diagram of a control circuit of a power supply according to an embodiment of the present application. Figure 1 As shown, it includes a control unit, which includes a first switching device 10, a second switching device 11, a first voltage dividing unit 12 and a second voltage dividing unit 13. The control end of the first switching device 10 is used to input a control signal. The first end of the first switching device 10 is connected to the first input end of the control circuit, the second end of the first switching device 10 is connected to the control end of the second switching device 11, the first end of the second switching device 11 is connected between the first end of the first voltage dividing unit 12 and the DC power supply end, the second end of the second switching device 11 is connected to the first end of the second voltage dividing unit 13, the second end of the second voltage dividing unit 13 is connected to the first end of the first switching device 10, the first end of the first voltage dividing unit 12 is connected to the connecting branch between the second switching device 11 and the second input end of the control circuit, the second end of the first voltage dividing unit 12 is connected to the connecting branch between the second voltage dividing unit 13 and the first switching device 10, and the operation of the second switching device 11 is controlled by the control signal.

[0030] In practical applications, when using a standard POE switch for power supply, in addition to using a safe voltage, the device also performs a "handshake" test before supplying power, checking the compatibility of the transmitter and receiver. If the receiver does not respond, power will not be supplied. The second voltage divider unit acts as a "dummy load," responding to the power supply's test and thereby receiving power. When multiple power ports are powered simultaneously, the first switching device and the first voltage divider unit jointly control the periodic operation of the second switching device by adjusting the duty cycle through a control signal. The second switching device then controls the second voltage divider unit to reduce load consumption and can even shut down the load. In practical applications, the first switching device can be set to control the switching signal frequency of the second switching device with a duty cycle of 50% to 60% and an interval of 1ms. This ensures that the power supply detects the receiving end, maintains power connection, and reduces load consumption. The duty cycle and interval are designed based on a load current of 10mA. The power supply detects whether the receiving end is disconnected based on the DC current flowing from the power supply to the receiving end. When the current remains below the threshold I min (5~10mA) state duration>T mpdWhen the power supply detects that the receiving end does not exist (300ms to 400ms), the power supply end cuts off the power supply. When the receiving end device is disconnected from the network, the power supply end stops supplying power at a certain time interval (300ms to 400ms) and repeats the above detection process to detect whether the terminal of the cable is connected to the receiving end device. Therefore, the above duty cycle and time interval are not unique. Those skilled in the art can set them by themselves as long as they meet the detection range of the above power supply end. When the power supply end detects a compatible receiving end and completes the classification of the receiving end, the power supply end starts to supply power to the subsequent load. At this time, the voltage difference between the first input end and the second input end can be 36~57V. The above-mentioned first switching device can be a transistor or a field effect transistor, the above-mentioned second switching device can be a field effect transistor, the above-mentioned first voltage divider unit can be one or more voltage divider resistors, and the above-mentioned second voltage divider unit can be one or more voltage divider resistors. The above-mentioned control circuit can be applied to POE power supply systems of different standards.

[0031] In an embodiment of the present invention, the control circuit of the power supply includes a first switching device, a second switching device, a first voltage dividing unit and a second voltage dividing unit. A control signal is input to the first switching device to control the working state of the first switching device. Since the first switching device is electrically connected to the second switching device, the control signal indirectly controls the operation of the second switching device. By controlling the working state of the second switching device, the operation of the second voltage dividing unit is controlled. In this way, when the circuit is applied to the POE power supply circuit, since the second voltage dividing unit is in the on state (working state), when the power supply end tests whether the circuit has a power supply demand, the power supply demand can be detected, so that the circuit can be controlled so that it does not lose power.

[0032] In a specific embodiment of the present application, Figure 2 As shown, the control circuit also includes a third switching device 14, a third voltage divider unit 15, and a fourth voltage divider unit 16. The control terminal of the third switching device 14 is connected to the first terminal of the third voltage divider unit 15, the first terminal of the third switching device 14 is connected to the second input terminal of the control circuit, the second terminal of the third switching device 14 is connected to the DC power supply terminal, the second terminal of the third voltage divider unit 15 is connected between the first terminal of the third switching device 14 and the second input terminal of the control circuit, the first terminal of the fourth voltage divider unit 16 is connected to the first terminal of the third voltage divider unit 15, and the second terminal of the fourth voltage divider unit 16 is connected between the first input terminal of the control circuit and the ground terminal. In the above circuit, the third switching device can prevent current from flowing back through the DC power supply input terminal, ensuring independent power supply between each path. Before setting the power supply priority, the priority power supply order is determined by voltage comparison, and the third and fourth voltage divider units perform voltage division. The above third switching device can be a field effect transistor, the above third voltage divider unit can be one or more voltage divider resistors, and the above fourth voltage divider unit can be one or more voltage divider resistors.

[0033] To further simplify the circuit, in a specific embodiment of the present application, the third switching device is a second PMOS transistor, the gate of the second PMOS transistor is the control terminal of the third switching device, the drain of the second PMOS transistor is the first terminal of the third switching device, the source of the second PMOS transistor is the second terminal of the third switching device, the third voltage divider unit is at least one voltage divider resistor, and the fourth voltage divider unit includes a first voltage divider sub-unit and a second voltage divider sub-unit, the two ends of the first voltage divider sub-unit are respectively connected to the first end of the third voltage divider unit and the first end of the second voltage divider sub-unit, and the second end of the second voltage divider sub-unit is connected to the connecting branch between the fourth voltage divider unit and the first end of the control circuit. The above circuit uses common components such as MOS transistors and resistors to construct a logic circuit, which can further reduce the complexity of the power supply control circuit.

[0034] In another specific embodiment of the present application, Figure 2 As shown, the control circuit further includes a fourth switch device 17. The control terminal of the fourth switch device 17 is connected between the first and second voltage divider subunits, the first terminal of the fourth switch device 17 is connected to the second terminal of the second voltage divider subunit, and the second terminal of the fourth switch device 17 is connected to the ground terminal. In the above circuit, the fourth switch device can prevent current from flowing back through the ground terminal, ensuring independent power supply between each path. In the above circuit, when the third switch device is turned on, the second input terminal is connected to the DC power supply terminal. When the fourth switch device is turned on, the first input terminal is connected to GND. The voltage difference between the DC power supply terminal and the ground terminal can be 36-57V.

[0035] In another specific embodiment of the present application, Figure 2 As shown, the control circuit also includes a protection unit, which includes a first diode 18. The cathode of the first diode 18 is connected to the first input terminal of the control circuit, and the anode of the first diode 18 is connected to the connecting branch between the first switching device and the first voltage divider unit. In the above circuit, the first diode functions to form a blocking circuit. The forward conduction and reverse blocking characteristics of the first diode can block the return current path. In addition, the multiple POE power supplies maintain independent operation. If a power outage occurs on one port, the other ports can still be powered normally, thus achieving power-off protection.

[0036] To further simplify the circuit, in another specific embodiment of the present application, the first switching device is a PNP transistor, the base of the PNP transistor is the control terminal of the first switching device, the emitter of the PNP transistor is the first terminal of the first switching device, the collector of the PNP transistor is the second terminal of the first switching device, the second switching device is a first PMOS transistor, the gate of the first PMOS transistor is the control terminal of the second switching device, the drain of the first PMOS transistor is the first terminal of the second switching device, and the source of the first PMOS transistor is the second terminal of the second switching device. The first voltage divider unit includes at least one voltage divider resistor, and the second voltage divider unit includes at least one voltage divider resistor. The total resistance of the second voltage divider unit can be 5k ohms. The above circuit uses common components such as transistors, MOS transistors, and resistors to construct a logic circuit, which can further reduce the complexity of the power supply control circuit. The above first switching device can also be replaced by an NPN transistor or a MOS transistor. If an NPN transistor is used, the collector of the NPN transistor is the first terminal of the first switching device, and the base of the NPN transistor is the control terminal of the first switching device. If a MOS transistor is used, the gate of the MOS transistor is the control terminal of the first switch device, and the drain and source are the first terminal and the second terminal of the first switch device respectively.

[0037] In another specific embodiment of the present application, the fourth switching device is an NMOS transistor, the gate of the NMOS transistor serves as the control terminal of the fourth switching device, the source of the NMOS transistor serves as the first terminal of the fourth switching device, and the drain of the NMOS transistor serves as the second terminal of the fourth switching device. By constructing a logic circuit using MOS transistors, the above circuit can further reduce the complexity of the power supply control circuit.

[0038] The embodiment of the present application also provides a POE power supply circuit. Figure 3 1 is a circuit diagram of a POE power supply circuit according to an embodiment of the present application. Figure 3 As shown, it includes: at least one power supply end; at least one network port 20, the power supply end is connected to the network port 20; at least one power receiving end 22, the power receiving end 22 is connected to the network port 20; at least one control circuit 23 of any type, the output end of the power receiving end 22 is connected to the first input end and the second input end of the control circuit 23, and the two ends of the control circuit 23 are respectively connected to the power receiving end 22 and the DC power supply end; a conversion circuit 25, a first end of the conversion circuit 25 is connected to the DC power supply end, and a second end of the conversion circuit 25 is connected to the ground end, and the conversion circuit 25 is used to reduce the voltage output by the control circuit 23.

[0039] In practice, the power supply and receiving end are connected via an RJ45 network port. The power supply can transmit a 44V-57V voltage to the receiving end via a twisted pair cable (the network port). The receiving end is then connected to a step-down circuit to convert the output DC power to the required voltage. This POE power supply circuit can be applied to different types of power supply systems, such as those with passive POE function or those with DC-Jack function.

[0040] The control circuit of the above-mentioned power supply includes a first switching device, a second switching device, a first voltage divider unit and a second voltage divider unit. The working state of the first switching device is controlled by inputting a control signal to the first switching device. Since the first switching device is electrically connected to the second switching device, the control signal indirectly controls the operation of the second switching device. By controlling the working state of the second switching device, the operation of the second voltage divider unit is controlled. In this way, when the circuit is applied to the POE power supply circuit, since the second voltage divider unit is in the on state (working state), when the power supply end tests whether the line has a power supply demand, the power supply demand can be detected, so that the line can be controlled to not lose power.

[0041] In a specific embodiment of the present application, Figure 3 As shown, the POE power supply circuit also includes: at least one second diode 24, the anode of the second diode 24 is connected to the control circuit 23, and the cathode of the second diode 24 is connected to the DC power supply terminal. In the above circuit, the role of the second diode is to ensure that each port can work independently.

[0042] In another specific embodiment of the present application, Figure 3 As shown, the POE power supply circuit further includes: at least one rectifier circuit 21, which is connected between the network port 20 and the power receiving end 22. In the above circuit, the rectifier circuit can reduce the power consumption of the POE power supply circuit. The above rectifier circuit can be a diode bridge or a MOS tube bridge.

[0043] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0044] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the above-mentioned units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0045] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0046] 1) The control circuit of the power supply of the present application includes a control unit, which includes a first switching device, a second switching device, a first voltage divider unit and a second voltage divider unit. The working state of the first switching device is controlled by inputting a control signal to the first switching device. Since the first switching device is electrically connected to the second switching device, the control signal indirectly controls the operation of the second switching device. By controlling the working state of the second switching device, the operation of the second voltage divider unit is controlled. In this way, when the circuit is applied to the POE power supply circuit, since the second voltage divider unit is in the on state (working state), when the power supply end tests whether the circuit has a power supply demand, the power supply demand can be detected, so that the circuit can be controlled to not lose power.

[0047] 2) The POE power supply circuit of the present application includes at least one power supply end, at least one network port, at least one power receiving end, at least one control circuit of any type, and a conversion circuit. In the control circuit, a control signal is input to the first switching device to control the working state of the first switching device. Since the first switching device is electrically connected to the second switching device, the control signal indirectly controls the operation of the second switching device. By controlling the working state of the second switching device, the operation of the second voltage divider unit is controlled. In this way, when the circuit is applied to the POE power supply circuit, since the second voltage divider unit is in the on state (working state), when the power supply end tests whether the circuit has a power supply demand, the power supply demand can be detected, thereby controlling the circuit to not lose power.

[0048] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A power supply control circuit, characterized in that: The control unit includes a first switching device, a second switching device, a first voltage dividing unit and a second voltage dividing unit, the control end of the first switching device is used to input a control signal, the first end of the first switching device is connected to the first input end of the control circuit, the second end of the first switching device is connected to the control end of the second switching device, the first end of the second switching device is connected between the first end of the first voltage dividing unit and the DC power supply end, the second end of the second switching device is connected to the first end of the second voltage dividing unit, the second end of the second voltage dividing unit is connected to the first end of the first switching device, the first end of the first voltage dividing unit is connected to the connection branch between the second switching device and the second input end of the control circuit, and the second end of the first voltage dividing unit is connected to the first end of the first switching device. The two ends are connected to the connection branch between the second voltage dividing unit and the first switching device, and the operation of the second switching device is controlled by the control signal. The control circuit also includes a third switching device, a third voltage dividing unit and a fourth voltage dividing unit. The control end of the third switching device is connected to the first end of the third voltage dividing unit, the first end of the third switching device is connected to the second input end of the control circuit, the second end of the third switching device is connected to the DC power supply end, the second end of the third voltage dividing unit is connected between the first end of the third switching device and the second input end of the control circuit, the first end of the fourth voltage dividing unit is connected to the first end of the third voltage dividing unit, and the second end of the fourth voltage dividing unit is connected between the first input end of the control circuit and the ground end.

2. The control circuit according to claim 1, wherein: The third switching device is a second PMOS tube, the gate of the second PMOS tube is the control end of the third switching device, the drain of the second PMOS tube is the first end of the third switching device, and the source of the second PMOS tube is the second end of the third switching device. The third voltage dividing unit is at least one voltage dividing resistor, and the fourth voltage dividing unit includes a first voltage dividing sub-unit and a second voltage dividing sub-unit. The two ends of the first voltage dividing sub-unit are respectively connected to the first end of the third voltage dividing unit and the first end of the second voltage dividing sub-unit, and the second end of the second voltage dividing sub-unit is connected to the connection branch between the fourth voltage dividing unit and the first end of the control circuit.

3. The control circuit according to claim 2, characterized in that: The control circuit further includes: A fourth switching device, wherein the control end of the fourth switching device is connected between the first voltage dividing subunit and the second voltage dividing subunit, the first end of the fourth switching device is connected to the second end of the second voltage dividing subunit, and the second end of the fourth switching device is connected to the ground end.

4. The control circuit according to claim 1, wherein: The control circuit further includes: The protection unit includes a first diode, a cathode of the first diode is connected to the first input end of the control circuit, and an anode of the first diode is connected to a connection branch between the first switching device and the first voltage dividing unit.

5. The control circuit according to claim 1, wherein: The first switching device is a PNP transistor, the base of the PNP transistor is the control end of the first switching device, the emitter of the PNP transistor is the first end of the first switching device, and the collector of the PNP transistor is the second end of the first switching device. The second switching device is a first PMOS transistor, the gate of the first PMOS transistor is the control end of the second switching device, the drain of the first PMOS transistor is the first end of the second switching device, and the source of the first PMOS transistor is the second end of the second switching device. The first voltage dividing unit includes at least one voltage dividing resistor, and the second voltage dividing unit includes at least one voltage dividing resistor.

6. The control circuit according to claim 3, characterized in that: The fourth switching device is an NMOS tube, the gate of the NMOS tube is the control end of the fourth switching device, the source of the NMOS tube is the first end of the fourth switching device, and the drain of the NMOS tube is the second end of the fourth switching device.

7. A POE power supply circuit, characterized in that: include: at least one power supply terminal; At least one network port, the power supply end being connected to the network port; at least one power receiving end, the power receiving end being connected to the network port; At least one control circuit according to any one of claims 1 to 6, wherein the output terminal of the power receiving terminal is connected to the first input terminal and the second input terminal of the control circuit, and the two ends of the control circuit are respectively connected to the power receiving terminal and the DC power supply terminal; A conversion circuit, wherein a first end of the conversion circuit is connected to the DC power supply end, a second end of the conversion circuit is connected to the ground end, and the conversion circuit is used to reduce the voltage output by the control circuit.

8. The POE power supply circuit according to claim 7, characterized in that: The POE power supply circuit also includes: At least one second diode, wherein the anode of the second diode is connected to the control circuit, and the cathode of the second diode is connected to the DC power supply terminal.

9. The POE power supply circuit according to claim 7, characterized in that: The POE power supply circuit also includes: At least one rectifier circuit, one of the rectifier circuits is connected between the network port and the power receiving end.

Images