A surge protection circuit and PoE power supply system

Abstract

The application discloses a surge protection circuit and a PoE power supply system, and relates to the technical field of surge protection. The surge protection circuit comprises a differential mode protection circuit and a first common mode protection circuit. The differential mode protection circuit is directly connected in parallel with a power supply path of a PD chip, can quickly respond to and absorb differential mode surges generated by a PoE network port and a direct current power supply. The first common mode protection circuit can effectively absorb common mode surges generated by the PoE network port and / or the direct current power supply by establishing a discharge path between a key node of a non-isolated power supply module input end and a PD chip grounding pin, and can also be realized when no protection ground is connected. The two are combined to form a complete protection system covering various surge types, which can effectively prevent various surges from damaging internal circuits due to a non-isolated common ground architecture.

Description

Technical Field

[0001] This application relates to the field of surge protection technology, and in particular to a surge protection circuit and a PoE power receiving system. Background Technology

[0002] During the application of communication products, overvoltage and overcurrent caused by lightning strikes and other reasons can damage the device ports. For dual-powered products that support both Power over Ethernet (PoE) and DC power supply, the network cable and DC power cable, as external cables, are easily used as input ports for lightning surges.

[0003] In existing technologies, a power module with isolation function is usually set up between the PoE power supply and the DC power supply for coupling, separating the ground of the PoE power supply from the ground of the DC power supply, so that most of the surges can be isolated outside the system.

[0004] The industry is gradually replacing the aforementioned isolated design with non-isolated designs. For systems that use non-isolated power modules for electrical coupling, the PoE power supply ground, DC power supply ground, and system operating ground are directly connected, allowing surges input from the DC power supply port or PoE power supply port to be conducted unimpeded within the system. This makes it difficult to effectively protect against both common-mode and differential-mode surges using the traditional technologies mentioned above. Utility Model Content

[0005] The main objective of this application is to provide a surge protection circuit and a PoE power receiving system, aiming to solve the technical problem of how to improve the surge protection capability of a PoE power receiving system with a non-isolated power module.

[0006] To achieve the above objectives, this application provides a surge protection circuit for a PoE power receiving system. The PoE power receiving system includes a rectifier module, a PD chip, and a non-isolated power module. The power input pin of the PD chip is connected to the positive output terminal of the rectifier module and the positive input terminal of the non-isolated power module, respectively. The ground pin of the PD chip is connected to the negative output terminal of the rectifier module and a reference ground, respectively. The power return pin of the PD chip is connected to the negative input terminal of the non-isolated power module and a power ground. The input terminal of the rectifier module is used to connect to the PoE network port, and the non-isolated power module is used to connect to the load in parallel with a DC power supply. The surge protection circuit includes: a differential mode protection circuit and a first common mode protection circuit; The first terminal of the differential mode protection circuit is connected to the power input pin of the PD chip, the second terminal of the differential mode protection circuit is connected to the reference ground, the third terminal of the differential mode protection circuit is connected to the positive terminal of the DC power supply, the fourth terminal of the differential mode protection circuit is used to connect to the positive output terminal of the non-isolated power module, and the fifth terminal of the differential mode protection circuit is connected to the power ground, which is used to absorb the differential mode surge generated by the PoE port and / or the DC power supply. The first terminal of the first common-mode protection circuit is connected to the positive input terminal of the non-isolated power module, the second terminal of the first common-mode protection circuit is connected to the negative input terminal of the non-isolated power module, and the third terminal of the first common-mode protection circuit is connected to the ground pin of the PD chip, for absorbing common-mode surges generated by the PoE port and / or the DC power supply.

[0007] In one embodiment, the differential mode protection circuit includes: a first TVS diode and a second TVS diode; The first end of the first TVS diode is connected to the positive terminal of the DC power supply, and the second end of the first TVS diode is connected to the power supply ground. The first end of the second TVS diode is connected to the power input pin of the PD chip, and the second end of the second TVS diode is connected to the ground pin of the PD chip.

[0008] In one embodiment, the differential mode protection circuit includes: a first diode; The anode of the first diode is connected to the first terminal of the first TVS diode, and the cathode of the first diode is used to connect to the positive output terminal of the non-isolated power supply module.

[0009] In one embodiment, the first common-mode protection circuit includes: a third TVS diode and a second diode; The first end of the third TVS diode is connected to the positive input terminal of the non-isolated power module, and the second end of the third TVS diode is connected to the negative input terminal of the non-isolated power module and the cathode of the second diode, respectively. The anode of the second diode is connected to the ground pin of the PD chip.

[0010] In one embodiment, the surge protection circuit further includes: a second common-mode protection circuit; The first terminal of the second common-mode protection circuit is connected to the input terminal of the rectifier module, the second terminal of the second common-mode protection circuit is connected to the protective ground, the third terminal of the second common-mode protection circuit is connected to the positive terminal of the DC power supply, and the fourth terminal of the second common-mode protection circuit is connected to the power supply ground. The second common-mode protection circuit is used to discharge the common-mode surge generated by the PoE port and / or the DC power supply to the protective ground.

[0011] In one embodiment, the second common-mode protection circuit includes: a fourth TVS diode to a ninth TVS diode; The input terminals of the rectifier module include a first positive input port, a second positive input port, a first negative input port, and a second negative input port; The first end of the fourth TVS diode is connected to the first positive input port of the rectifier module, the first end of the fifth TVS diode is connected to the first negative input port of the rectifier module, the first end of the sixth TVS diode is connected to the second positive input port of the rectifier module, the first end of the seventh TVS diode is connected to the second negative input port of the rectifier module, the first end of the eighth TVS diode is connected to the positive terminal of the DC power supply, and the first end of the ninth TVS diode is connected to the power ground; the second ends of the fourth TVS diode, the fifth TVS diode, the sixth TVS diode, the seventh TVS diode, the eighth TVS diode, and the ninth TVS diode are connected to the protective ground.

[0012] In one embodiment, the non-isolated power module includes: a BUCK circuit and a third diode; When the DC power supply is connected to the positive output terminal of the BUCK circuit, the positive input terminal of the BUCK circuit is connected to the power input pin of the PD chip, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the power ground, the positive output terminal of the BUCK circuit is the anode of the third diode, and the cathode of the third diode is connected to the load.

[0013] In one embodiment, when the DC power supply is connected to the positive input terminal of the BUCK circuit, the positive input terminal of the BUCK circuit is connected to the cathode of the third diode, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the power ground, and the positive output terminal of the BUCK circuit is connected to the load; the anode of the third diode is connected to the power input pin of the PD chip.

[0014] In one embodiment, the rectifier module includes: a fourth diode to an eleventh diode; The cathode of the fourth diode and the anode of the fifth diode are connected to the first positive output port of the PoE network port, the cathode of the sixth diode and the anode of the seventh diode are connected to the first negative output port of the PoE network port, the cathode of the eighth diode and the anode of the ninth diode are connected to the second positive output port of the PoE network port, and the cathode of the tenth diode and the anode of the eleventh diode are connected to the second positive output port of the PoE network port. The anodes of the fourth diode, the sixth diode, the eighth diode, and the tenth diode are connected to the ground pin of the PD chip, and the cathodes of the fifth diode, the seventh diode, the ninth diode, and the eleventh diode are connected to the power input pin of the PD chip.

[0015] To achieve the above objectives, this application also proposes a PoE power receiving system, which employs the surge protection circuit described above.

[0016] This application provides a surge protection circuit and a PoE power receiving system. The surge protection circuit includes a differential mode protection circuit and a first common mode protection circuit. The first terminal of the differential mode protection circuit is connected to the power input pin of the PD chip, the second terminal of the differential mode protection circuit is connected to a reference ground, the third terminal of the differential mode protection circuit is connected to the positive terminal of the DC power supply, the fourth terminal of the differential mode protection circuit is connected to the positive output terminal of the non-isolated power module, and the fifth terminal of the differential mode protection circuit is connected to the power ground, for absorbing differential mode surges generated by the PoE port and / or the DC power supply. The first terminal of the first common mode protection circuit is connected to the positive input terminal of the non-isolated power module, the second terminal of the first common mode protection circuit is connected to the negative input terminal of the non-isolated power module, and the third terminal of the first common mode protection circuit is connected to the ground pin of the PD chip, for absorbing common mode surges generated by the PoE port and / or the DC power supply.

[0017] The differential-mode protection circuit is directly connected in parallel to the power path of the PD chip, enabling it to quickly respond to and absorb differential-mode surges generated by the PoE port and DC power supply. Meanwhile, the first common-mode protection circuit effectively absorbs common-mode surges generated by the PoE port and / or DC power supply by establishing a discharge path between the input terminal of the non-isolated power module and the critical node of the PD chip's ground pin, and this protection is also effective when no protective ground is connected. Together, these two circuits form a complete protection system covering multiple surge types, effectively preventing damage to internal circuits caused by various surges due to the non-isolated common-ground architecture. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the surge protection circuit provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the surge protection circuit provided in Embodiment 2 of this application; Figure 3 A schematic diagram of a surge protection circuit according to Embodiment 3 of this application; Figure 4 This is another structural schematic diagram provided for embodiment three of the surge protection circuit of this application.

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0024] This application presents a surge protection circuit according to a first embodiment. Please refer to [link / reference]. Figure 1 This is applied to a PoE power receiving system, which includes a rectifier module 11, a PD chip 12, and a non-isolated power module 13. The power input pin of the PD chip 12 is connected to the positive output terminal of the rectifier module 11 and the positive input terminal of the non-isolated power module 13, respectively. The ground pin of the PD chip 12 is connected to the negative output terminal of the rectifier module 11 and the reference ground, respectively. The power return pin of the PD chip 12 is connected to the negative input terminal of the non-isolated power module 13 and the power ground. The input terminal of the rectifier module 11 is used to connect to the PoE network port 21, and the non-isolated power module 13 is used to connect to the load 23 in parallel with the DC power supply 22. The surge protection circuit includes: a differential mode protection circuit 31 and a first common mode protection circuit 32; The first terminal of the differential mode protection circuit 31 is connected to the power input pin of the PD chip 12, the second terminal of the differential mode protection circuit 31 is connected to the reference ground, the third terminal of the differential mode protection circuit 31 is connected to the positive terminal of the DC power supply 22, the fourth terminal of the differential mode protection circuit 31 is used to connect to the positive output terminal of the non-isolated power module 13, and the fifth terminal of the differential mode protection circuit 31 is connected to the power ground, which is used to absorb the differential mode surge generated by the PoE port 21 and / or the DC power supply 22. The first end of the first common-mode protection circuit 32 is connected to the positive input terminal of the non-isolated power module 13, the second end of the first common-mode protection circuit 32 is connected to the negative input terminal of the non-isolated power module 13, and the third end of the first common-mode protection circuit 32 is connected to the ground pin of the PD chip 12, for absorbing the common-mode surge generated by the PoE port 21 and / or the DC power supply 22.

[0025] It should be understood that, in this embodiment, the surge protection circuit proposed in this embodiment is mainly applied to a PoE power receiving system that supports simultaneous power supply from PoE and DC power supply 22. The PoE power receiving system includes a rectifier module 11, a PD chip 12, and a non-isolated power supply module 13. Specifically, the rectifier module 11 can be a bridge rectifier circuit composed of several diodes, used to rectify the PoE power supply into a DC power supply of fixed polarity; the PD chip 12 refers to a power receiving device controller chip conforming to the IEEE 802.3af / at / bt standard, which is responsible for executing power negotiation logic such as detection, classification, and soft start; the non-isolated power supply module 13 refers to a DC-DC converter using a non-isolated topology, whose input ground and output ground are directly connected, which can step down the voltage on the high-voltage side of the input, thereby outputting a lower operating voltage to the load 23.

[0026] There are two ways to connect the non-isolated power supply module 13 and the DC power supply 22 in parallel. When the DC power supply voltage is suitable (low enough), the output side of the non-isolated power supply module 13 can be connected in parallel with the DC power supply 22 to the load 23. In this case, the non-isolated power supply module 13 only performs voltage reduction processing on the PoE power supply. When the DC power supply voltage is too high, the input side of the non-isolated power supply module 13 can be connected in parallel with the DC power supply 22 to the load. In this case, the non-isolated power supply module 13 can perform voltage reduction processing on both the PoE power supply and the DC power supply. Figure 1 Only the output side of the non-isolated power module 13 is shown connected in parallel with the DC power supply 22.

[0027] It should be noted that, in this embodiment, the PD chip 12 integrates a high-voltage MOSFET switch. Externally, it has at least a power input pin for detecting the input voltage, a ground pin serving as a PoE reference ground and connected to the source of the MOSFET switch within the PD chip 12, and a power return pin for providing a current return path and connected to the drain of the MOSFET switch within the PD chip 12. The two ends of the current transmission path of the high-voltage MOSFET switch within the PD chip 12 are connected to the power return pin and the ground pin, respectively.

[0028] As is readily understood, in this embodiment, DC power supply 22 refers to a power source that can provide a stable DC voltage, specifically a power adapter, whose positive terminal can be directly or indirectly connected to load 23, and whose negative terminal is connected to power ground. PoE port 21 refers to an Ethernet cable interface, which has the functions of data transmission and power delivery, and its output end has four output interfaces, through which AC power can be transmitted.

[0029] It should be noted that in this embodiment, "reference ground" refers to the reference ground corresponding to the PoE port 21, that is, the return path of the PoE input power; "power ground" refers to the working reference ground of the power conversion part; the load 23 can be a device, equipment or system that needs to consume electrical energy and needs the PoE power receiving system to provide low voltage power supply in order to work normally.

[0030] It should be understood that a common-mode surge refers to an overvoltage occurring simultaneously between each power transmission line and the protective ground, while a differential-mode surge refers to an overvoltage occurring between any two power transmission lines. In the PoE power receiving system proposed in this embodiment, common-mode surges and / or differential-mode surges may occur, typically caused by lightning strikes at the power ports (including the PoE network port 21 and the power port of the DC power supply 22). Among these, the common-mode surge is mainly an overvoltage occurring between the DC power supply 22 and the protective ground PE, which can be understood as a common-mode surge at the power port. In some extreme scenarios of actual use (e.g., the external network cable of the prototype hangs down to the soil on the ground, or the external PoE switch of the prototype is damaged, causing the PoE network port 21 to be short-circuited with the protective ground PE), the reference ground of the prototype will be directly short-circuited with the protective ground PE through the diode of the rectifier module 11, so that the common-mode surge can be discharged through the devices inside the prototype. The first common-mode protection circuit 32 and other related circuits with common-mode protection functions proposed in this embodiment are mainly for protection against the above-mentioned situations.

[0031] It is worth noting that, in addition, common-mode surges may also exist in actual situations, namely surges through the PoE port 21 transmission line to the protective earth (PE). When a circuit structure with isolation functionality is configured, both the power port common-mode surge and the network port common-mode surge can be protected by the isolated circuit structure. In this embodiment, since there is no circuit structure with isolation functionality, an additional common-mode protection circuit is required to protect against the aforementioned common-mode surges. Among them, the common-mode surge of the power port includes positive common-mode surge and negative common-mode surge. In the above extreme scenario, the positive common-mode surge can be regarded as entering from the power port of DC power supply 22, flowing to the reference ground first, then through the diode in the rectifier module 11 to the PoE network port 21, and being discharged to the protective ground. The negative common-mode surge can be regarded as entering from the PoE network port 21 (the protective ground of the network port), then through the positive input terminal of PD chip 12, through the electronic components set between the positive and negative input terminals of non-isolated power module 13 to the power ground, and flowing to the power port of DC power supply 22. In this embodiment, since a non-isolated power module 13 is used, its negative input and negative output terminals share a common ground (both connected to the power ground). Therefore, when the differential mode protection circuit 31 and the first common mode protection circuit 32 are not connected, the positive surge can be specifically regarded as being discharged through the transmission path of "power ground of DC power supply 22 - power return pin of PD chip 12 - MOSFET switch inside PD chip 12 - ground pin of PD chip 12 - PoE port 21". The negative surge can be equivalently regarded as being discharged through the transmission path of "PoE port 21 - positive input terminal of PD chip 12 - non-isolated power module 13 (breakdown) - power ground of DC power supply 22". When the positive surge is discharged through the above discharge path, the MOSFET switch inside PD chip 12 will be broken down by the positive surge, thereby damaging PD chip 12.

[0032] It is easy to understand that in this embodiment, the differential mode protection circuit 31 is connected in parallel on the main power transmission path, such as between the positive terminal and the negative terminal (power ground) of the DC power supply 22, and between the power input pin and the ground pin of the PD chip 12. It can limit the overvoltage between lines and absorb differential mode surges generated from the DC power supply 22 or the PoE network port 21 in a timely manner to prevent differential mode surges from damaging the electronic components inside the system. The first common mode protection circuit 32 is connected across the critical nodes inside the system, such as between the positive input terminal and the negative input terminal of the non-isolated power module 13, and between the power return pin and the ground pin of the PD chip 12. It can provide a low-impedance internal discharge path for common mode surges to prevent common mode surges from breaking down the electronic components inside the PD chip 12 or the non-isolated power module 13.

[0033] It should be noted that special circumstances may arise during the actual construction of a PoE powered system, such as the user not connecting to the power ground, a loose power ground, incomplete grounding, or the prototype lacking a grounding wire design. In this embodiment, the internal discharge circuit composed of the first common-mode protection circuit 32 can effectively absorb the common-mode surge transmitted in the system when it is not connected to the "protective ground," and is suitable for a PoE and DC dual-power supply system topology with a non-isolated design.

[0034] It is easy to understand that, in this embodiment, based on the cooperation of the differential mode protection circuit 31 and the first common mode protection circuit 32, various types of surge impacts can be addressed. When a differential mode surge occurs, the differential mode protection circuit 31 acts as the first line of defense, quickly absorbing energy. When a common mode surge occurs and the equipment is not grounded, the first common mode protection circuit 32 immediately activates as the final safeguard, effectively absorbing the common mode surge current that is about to damage the PD chip 12 and the non-isolated power module 13 through the breakdown and conduction of its internal components (such as TVS diodes), thereby achieving a highly efficient, reliable protection effect that can cope with various types of surge impacts.

[0035] This application provides a surge protection circuit, which includes a differential mode protection circuit and a first common mode protection circuit. The differential mode protection circuit is directly connected in parallel to the power path of the PD chip, and can quickly respond to and absorb differential mode surges generated by the PoE port and / or DC power supply. The first common mode protection circuit effectively absorbs common mode surges generated by the PoE port and DC power supply by establishing a discharge path between the key nodes of the non-isolated power module input terminal and the PD chip ground pin, and can also achieve this even when no protective ground is connected. The combination of the two constitutes a complete protection system covering multiple surge types, which can effectively prevent various surges caused by non-isolated common ground architecture from damaging the internal circuits.

[0036] Based on the first embodiment of the surge protection circuit of this application, in the second embodiment of the surge protection circuit of this application, the contents that are the same as or similar to those in the first embodiment of the surge protection circuit described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 2 In this embodiment, the differential mode protection circuit 31 includes: a first TVS transistor Qt1 and a second TVS transistor Qt2; The first end of the first TVS diode Qt1 is connected to the positive terminal of the DC power supply 22, and the second end of the first TVS diode Qt1 is connected to the power supply ground. The first end of the second TVS transistor Qt2 is connected to the power input pin of the PD chip 12, and the second end of the second TVS transistor Qt2 is connected to the ground pin of the PD chip 12.

[0037] It should be noted that in this embodiment, the first TVS diode Qt1 is connected in parallel between the positive and negative terminals (power ground) of the DC power supply 22. Its breakdown voltage must be greater than the voltage provided by the DC power supply 22 (e.g., 12V), and its clamping voltage must be less than the maximum withstand voltage of the non-isolated power module 13 connected in the subsequent stage. It can be used to absorb differential-mode surges generated at the DC power supply 22. The second TVS diode Qt2 is connected in parallel on one side of the PoE port 21, specifically between the power input pin and the ground pin of the PD chip 12 connected after passing through the rectifier module 11. Its breakdown voltage must be greater than the maximum voltage that the PoE port 21 can provide (e.g., 57V), and its clamping voltage must be less than the maximum withstand voltage of the PD chip 12 (usually 100V). It can be used to absorb differential-mode surges from the PoE port 21.

[0038] Furthermore, in this embodiment, the differential mode protection circuit 31 includes: a first diode D1; The anode of the first diode D1 is connected to the first terminal of the first TVS transistor Qt1, and the cathode of the first diode D1 is used to connect to the positive output terminal of the non-isolated power supply module 13.

[0039] It should be noted that in this embodiment, the first diode D1 is a reverse connection protection diode, connected in series in the current transmission path of the positive terminal of the DC power supply 22. It can be used to prevent the DC power supply 22 from being mistakenly connected and burning out subsequent circuits. Simultaneously, it can also assist in the absorption of differential-mode surges. When a differential-mode surge occurs, it can block the reverse current path, forcing the negative differential-mode surge to flow to the aforementioned first TVS diode Qt1 for effective absorption.

[0040] Furthermore, in this embodiment, the first common-mode protection circuit 32 includes: a third TVS diode Qt3 and a second diode D2; The first end of the third TVS transistor Qt3 is connected to the positive input terminal of the non-isolated power module 13, and the second end of the third TVS transistor Qt3 is connected to the negative input terminal of the non-isolated power module 13 and the cathode of the second diode D2, respectively. The anode of the second diode D2 is connected to the ground pin of the PD chip 12.

[0041] It should be noted that in this embodiment, the third TVS diode Qt3 is connected in parallel between the positive and negative input terminals of the non-isolated power module 13. Its breakdown voltage is designed to be low (lower than the breakdown voltage of the second TVS diode Qt2), which ensures that it conducts before receiving a high-voltage common-mode surge, providing a discharge path for the common-mode surge. The second diode D2 can be a unidirectional TVS diode or a fast recovery diode, connected in parallel between the ground pin and the power return pin of the PD chip 12, that is, connected in parallel across the current transmission path of the internal MOSFET switch. It can prevent the MOSFET switch inside the PD chip 12 from receiving reverse surge voltage impact. In the above extreme case, since the protective ground and the reference ground, and the positive input terminal of the PD chip 12 are connected only by the diode in the rectifier module 11, the common-mode surge is discharged through the prototype. At this time, the third TVS diode Qt3 and the second diode D2 cooperate to provide a discharge path, thereby protecting the electronic components inside the system from damage due to the common-mode surge impact.

[0042] Furthermore, in this embodiment, the surge protection circuit further includes: a second common-mode protection circuit 33; The first terminal of the second common-mode protection circuit 33 is connected to the input terminal of the rectifier module 11, the second terminal of the second common-mode protection circuit 33 is connected to the protective ground, the third terminal of the second common-mode protection circuit 33 is connected to the positive terminal of the DC power supply 22, and the fourth terminal of the second common-mode protection circuit 33 is connected to the power supply ground. The second common-mode protection circuit 33 is used to discharge the common-mode surge generated by the PoE port 21 and / or the DC power supply 22 to the protective ground.

[0043] It should be noted that the protective ground is the PE line in the PoE power receiving system. In this embodiment, the second common-mode protection circuit 33 is a circuit structure that provides a transmission channel for common-mode surges to the protective ground. Working in conjunction with the first common-mode protection circuit 32, it can better protect against the impact of common-mode surges. When the system is successfully connected to the protective ground, the second common-mode protection circuit 33 acts as the primary discharger of common-mode surges; when the system is not connected or not fully connected to the protective ground, the first common-mode protection circuit 32 functions as a backup circuit, absorbing common-mode surges.

[0044] Furthermore, in this embodiment, the second common-mode protection circuit 33 includes: the fourth TVS transistor Qt4 to the ninth TVS transistor Qt9; The input terminals of the rectifier module 11 include a first positive input port, a second positive input port, a first negative input port, and a second negative input port; The first end of the fourth TVS diode Qt4 is connected to the first positive input port of the rectifier module 11, the first end of the fifth TVS diode Qt5 is connected to the first negative input port of the rectifier module 11, the first end of the sixth TVS diode Qt6 is connected to the second positive input port of the rectifier module 11, the first end of the seventh TVS diode Qt7 is connected to the second negative input port of the rectifier module 11, the first end of the eighth TVS diode Qt8 is connected to the positive terminal of the DC power supply 22, and the first end of the ninth TVS diode Qt9 is connected to the power ground; the second ends of the fourth TVS diode Qt4, the fifth TVS diode Qt5, the sixth TVS diode Qt6, the seventh TVS diode Qt7, the eighth TVS diode Qt8, and the ninth TVS diode Qt9 are connected to the protective ground.

[0045] It should be noted that in this embodiment, the fourth TVS diode Qt4, the fifth TVS diode Qt5, the sixth TVS diode Qt6, and the seventh TVS diode Qt7 are connected in parallel between the four input ports (four output ports of the PoE network port 21) of the rectifier module 11 and the protective ground, forming a common-mode protection array for the PoE network port 21. This array can absorb common-mode surges transmitted from the PoE network cable between the wire pair and the reference ground through breakdown. The eighth TVS diode Qt8 and the ninth TVS diode Qt9 are connected in parallel between the positive and negative terminals of the DC power supply 22, forming common-mode protection for the power port of the DC power supply 22. This array can absorb common-mode surges transmitted from the DC power supply 22 through breakdown.

[0046] Based on the first and / or second embodiments of the surge protection circuit of this application, in the third embodiment of the surge protection circuit of this application, the content that is the same as or similar to the first and second embodiments of the surge protection circuit described above can be referred to the above description and will not be repeated hereafter. Based on this, please refer to... Figure 3 as well as Figure 4 In this embodiment, the non-isolated power module 13 includes: a BUCK circuit 131 and a third diode D3; When the DC power supply 22 is connected to the positive output terminal of the BUCK circuit 131, the positive input terminal of the BUCK circuit 131 is connected to the power input pin of the PD chip 12, the negative input terminal and the negative output terminal of the BUCK circuit 131 are connected to the power ground, the positive output terminal of the BUCK circuit 131 is the anode of the third diode D3, and the cathode of the third diode D3 is connected to the load 23.

[0047] It should be noted that specific details can be found by referring to [the relevant source]. Figure 3In the connection shown, the output terminal (positive) of the DC power supply 22 is connected to the load 23 in parallel with the positive output terminal of the BUCK circuit 131 through the first diode D1 of the differential mode protection circuit 31. In this embodiment, the BUCK circuit 131 can specifically be a non-isolated DC-DC buck converter, which can convert the higher input voltage (the voltage provided by the PoE port 21) to the lower operating voltage required by the load 23. The third diode D3 can act as a reverse protection diode. When the DC power supply 22 is supplying power, the third diode D3 enters the cutoff state to prevent the voltage of the DC power supply 22 from flowing in reverse through the BUCK circuit 131 to the PoE power supply side.

[0048] In this embodiment, as Figure 3 The connection method shown is for cases where the voltage provided by the DC power supply 22 is low. In this case, the DC power supply 22 can directly supply power to the load 23 connected to the downstream stage through the first diode D1, while the PoE power supply can first be stepped down by the non-isolated power module 13, and then provide appropriate power to the load 23 through the third diode D3.

[0049] Furthermore, in this embodiment, when the DC power supply 22 is connected to the positive input terminal of the BUCK circuit 131, the positive input terminal of the BUCK circuit 131 is connected to the cathode of the third diode D3, the negative input terminal and the negative output terminal of the BUCK circuit 131 are connected to the power supply ground, and the positive output terminal of the BUCK circuit 131 is connected to the load 23; the anode of the third diode D3 is connected to the power input pin of the PD chip 12.

[0050] It should be noted that, in this embodiment, specific details can be found by referring to... Figure 4 The connection shown describes a scenario where the DC power supply 22 provides a higher voltage and is not synchronously connected to the PoE port 21. In this case, the output terminal (positive terminal) of the DC power supply 22 is connected to the positive input terminal of the BUCK circuit 131 through the first diode D1. After being stepped down by the BUCK circuit 131, the lower operating voltage required by the load 23 is output. In this embodiment, under the above conditions, the third diode D3 can also act as a reverse protection diode. When the PoE power supply is normal (connected solely to the PoE port 21), the third diode D3 enters the conducting state, and the BUCK circuit 131 steps down the power supply provided by the PoE port 21 to supply power to the load 23. When the DC power supply is normal (connected solely to the DC power supply 22), the third diode D3 enters the cutoff state to prevent the voltage provided by the DC power supply 22 from flowing back to the PoE power supply side. The BUCK circuit 131 steps down the power supply provided by the DC power supply 22 to supply power to the load 23. In this embodiment, as Figure 4 The connection method shown is mainly for situations where the voltage provided by DC power supply 22 is too high to directly power the load 23, thus achieving compatibility between high-voltage DC power supply and PoE power supply.

[0051] Furthermore, in this embodiment, the rectifier module 11 includes: a fourth diode D4 to an eleventh diode D11; The cathode of the fourth diode D4 and the anode of the fifth diode D5 are connected to the first positive output port of the PoE network port 21, the cathode of the sixth diode D6 and the anode of the seventh diode D7 are connected to the first negative output port of the PoE network port 21, the cathode of the eighth diode D8 and the anode of the ninth diode D9 are connected to the second positive output port of the PoE network port 21, and the cathode of the tenth diode D10 and the anode of the eleventh diode D11 are connected to the second positive output port of the PoE network port 21. The anodes of the fourth diode D4, the sixth diode D6, the eighth diode D8, and the tenth diode D10 are connected to the ground pin of the PD chip 12, and the cathodes of the fifth diode D5, the seventh diode D7, the ninth diode D9, and the eleventh diode D11 are connected to the power input pin of the PD chip 12.

[0052] It is easy to understand that in this embodiment, the fourth diode D4 to the eleventh diode D11 together form a bridge rectifier circuit, which can convert the four AC power provided by the PoE network port 21 into a set of differential DC power, so as to provide DC power to the PD chip 12 and the non-isolated power module 13 connected to the downstream stage.

[0053] In addition, to achieve the above objectives, embodiments of this application also provide a PoE power receiving system, wherein the PoE power receiving system employs the surge protection circuit described above.

[0054] The PoE power receiving system provided in this application adopts the surge protection circuit in the above embodiments. Compared with the prior art, the beneficial effects of the PoE power receiving system provided in this application are the same as the beneficial effects of the surge protection circuit provided in the above embodiments. Moreover, the other technical features of the PoE power receiving system are the same as the features disclosed in the methods of the above embodiments, and will not be repeated here.

[0055] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. A surge protection circuit, characterized in that, This invention is applied to a PoE power receiving system, which includes a rectifier module, a PD chip, and a non-isolated power module. The power input pin of the PD chip is connected to the positive output terminal of the rectifier module and the positive input terminal of the non-isolated power module, respectively. The ground pin of the PD chip is connected to the negative output terminal of the rectifier module and the reference ground, respectively. The power return pin of the PD chip is connected to the negative input terminal of the non-isolated power module and the power ground. The input terminal of the rectifier module is used to connect to the PoE network port, and the non-isolated power module is used to connect to the load in parallel with a DC power supply. The surge protection circuit includes: a differential mode protection circuit and a first common mode protection circuit; The first terminal of the differential mode protection circuit is connected to the power input pin of the PD chip, the second terminal of the differential mode protection circuit is connected to the reference ground, the third terminal of the differential mode protection circuit is connected to the positive terminal of the DC power supply, the fourth terminal of the differential mode protection circuit is used to connect to the positive output terminal of the non-isolated power module, and the fifth terminal of the differential mode protection circuit is connected to the power ground, which is used to absorb the differential mode surge generated by the PoE port and / or the DC power supply. The first terminal of the first common-mode protection circuit is connected to the positive input terminal of the non-isolated power module, the second terminal of the first common-mode protection circuit is connected to the negative input terminal of the non-isolated power module, and the third terminal of the first common-mode protection circuit is connected to the ground pin of the PD chip, for absorbing common-mode surges generated by the PoE port and / or the DC power supply.

2. The surge protection circuit as described in claim 1, characterized in that, The differential mode protection circuit includes: a first TVS diode and a second TVS diode; The first end of the first TVS diode is connected to the positive terminal of the DC power supply, and the second end of the first TVS diode is connected to the power supply ground. The first end of the second TVS diode is connected to the power input pin of the PD chip, and the second end of the second TVS diode is connected to the ground pin of the PD chip.

3. The surge protection circuit as described in claim 2, characterized in that, The differential mode protection circuit includes: a first diode; The anode of the first diode is connected to the first terminal of the first TVS diode, and the cathode of the first diode is used to connect to the positive output terminal of the non-isolated power supply module.

4. The surge protection circuit as described in claim 1, characterized in that, The first common-mode protection circuit includes: a third TVS diode and a second diode; The first end of the third TVS diode is connected to the positive input terminal of the non-isolated power module, and the second end of the third TVS diode is connected to the negative input terminal of the non-isolated power module and the cathode of the second diode, respectively. The anode of the second diode is connected to the ground pin of the PD chip.

5. The surge protection circuit as described in claim 1, characterized in that, The surge protection circuit also includes: a second common-mode protection circuit; The first terminal of the second common-mode protection circuit is connected to the input terminal of the rectifier module, the second terminal of the second common-mode protection circuit is connected to the protective ground, the third terminal of the second common-mode protection circuit is connected to the positive terminal of the DC power supply, and the fourth terminal of the second common-mode protection circuit is connected to the power supply ground. The second common-mode protection circuit is used to discharge the common-mode surge generated by the PoE port and / or the DC power supply to the protective ground.

6. The surge protection circuit as described in claim 5, characterized in that, The second common-mode protection circuit includes: the fourth TVS diode to the ninth TVS diode; The input terminals of the rectifier module include a first positive input port, a second positive input port, a first negative input port, and a second negative input port; The first end of the fourth TVS diode is connected to the first positive input port of the rectifier module, the first end of the fifth TVS diode is connected to the first negative input port of the rectifier module, the first end of the sixth TVS diode is connected to the second positive input port of the rectifier module, the first end of the seventh TVS diode is connected to the second negative input port of the rectifier module, the first end of the eighth TVS diode is connected to the positive terminal of the DC power supply, and the first end of the ninth TVS diode is connected to the power ground; the second ends of the fourth TVS diode, the fifth TVS diode, the sixth TVS diode, the seventh TVS diode, the eighth TVS diode, and the ninth TVS diode are connected to the protective ground.

7. The surge protection circuit as described in claim 1, characterized in that, The non-isolated power module includes: a BUCK circuit and a third diode; When the DC power supply is connected to the positive output terminal of the BUCK circuit, the positive input terminal of the BUCK circuit is connected to the power input pin of the PD chip, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the power ground, the positive output terminal of the BUCK circuit is the anode of the third diode, and the cathode of the third diode is connected to the load.

8. The surge protection circuit as described in claim 7, characterized in that, When the DC power supply is connected to the positive input terminal of the BUCK circuit, the positive input terminal of the BUCK circuit is connected to the cathode of the third diode, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the power ground, and the positive output terminal of the BUCK circuit is connected to the load; the anode of the third diode is connected to the power input pin of the PD chip.

9. The surge protection circuit as described in claim 1, characterized in that, The rectifier module includes: the fourth diode to the eleventh diode; The cathode of the fourth diode and the anode of the fifth diode are connected to the first positive output port of the PoE network port, the cathode of the sixth diode and the anode of the seventh diode are connected to the first negative output port of the PoE network port, the cathode of the eighth diode and the anode of the ninth diode are connected to the second positive output port of the PoE network port, and the cathode of the tenth diode and the anode of the eleventh diode are connected to the second positive output port of the PoE network port. The anodes of the fourth diode, the sixth diode, the eighth diode, and the tenth diode are connected to the ground pin of the PD chip, and the cathodes of the fifth diode, the seventh diode, the ninth diode, and the eleventh diode are connected to the power input pin of the PD chip.

10. A PoE power receiving system, characterized in that, The PoE power receiving system employs a surge protection circuit as described in any one of claims 1 to 9.

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