A power supply circuit

Abstract

This application provides a power supply circuit, relating to the field of circuit electronics, comprising: a first and second input terminal of a rectifier bridge unit connected to the corresponding wire core of the network port; a third and fourth input terminal of the rectifier bridge unit connected to the positive and negative terminals of an external DC terminal, respectively; and a fifth and sixth input terminal of the rectifier bridge unit connected to the corresponding center tap of the network transformer, respectively. The output terminals of the rectifier bridge unit are connected to a PD control unit and a power-on delay unit, respectively. An overcurrent protection unit is placed between the PD control unit and the power-on delay unit. The overall power supply unit is placed after the power-on delay unit. The power supply circuit is compatible with standard PoE power supply, non-standard PoE power supply, and direct power supply from external DC terminals. The addition of an overcurrent protection unit ensures normal operation of the overcurrent protection in the power supply circuit, while the addition of a power-on delay unit ensures that the filter capacitor in the power supply circuit does not affect the protocol signal.

Description

Technical Field

[0001] This application relates to the field of circuit electronics technology, specifically to a power supply circuit. Background Technology

[0002] Power over Ethernet (PoE) is a technology based on standard Ethernet cabling that provides DC power to devices connected to the other end of a standard Ethernet cable while transmitting data. A standard Ethernet cable has eight wires, four of which (1, 2, 3, and 6) are used for data transmission. PoE cleverly utilizes the unused wires 4 / 5 and 7 / 8, or the data wires (1, 2, 3, and 6), to transmit DC power simultaneously. Because DC power and data signals operate at different frequencies, they do not interfere with data transmission.

[0003] With the continuous development and progress of technology, the customer needs for various electronic products are also becoming more diverse. For electronic products such as civilian security and intelligent buildings, there will be many different power supply requirements depending on the on-site construction conditions, cost requirements, and performance requirements. Enterprises' production and management costs also require products to be compatible with all needs, so that a single solution can meet all scenarios and avoid the increased management costs caused by multiple versions.

[0004] Generally, electronic products are powered in three ways: standard PoE power supply, non-standard PoE power supply, and direct power supply from external DC terminals. In the process of developing this application, the inventors discovered that both standard and non-standard PoE power supplies use 4 / 5 and 7 / 8 wire pairs. Because they use the same wire pairs, the standard and non-standard PoE power supplies in the power supply circuit are incompatible. Utility Model Content

[0005] In response to this, this application provides a power supply circuit to solve the problem that existing non-standard PoE power supplies and standard PoE power supplies use the same wire pairs, resulting in incompatibility between standard PoE power supplies and non-standard PoE power supplies in the power supply circuit.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] This application discloses a power supply circuit, including: a rectifier bridge unit, a PD control unit, a power-on delay unit, a whole power supply unit, an overcurrent protection unit, and a network transformer;

[0008] The first and second input terminals of the rectifier bridge unit are connected to the corresponding wire cores of the network port. The third and fourth input terminals of the rectifier bridge unit are respectively connected to the positive and negative terminals of the external DC terminal. The fifth and sixth input terminals of the rectifier bridge unit are respectively connected to the center taps of the network transformer.

[0009] The output terminals of the rectifier bridge unit are respectively connected to the PD control unit and the power-on delay unit;

[0010] The overcurrent protection unit is located between the PD control unit and the power-on delay unit;

[0011] The power supply unit is located after the power-on delay unit.

[0012] Optionally, in the power supply circuit described above, the rectifier bridge unit includes: a first rectifier bridge, a second rectifier bridge, a third rectifier bridge, and a fourth rectifier bridge;

[0013] The first AC input terminal of the first rectifier bridge is connected to the first AC input terminal of the second rectifier bridge, and the connection point serves as the first input terminal of the rectifier bridge unit, which is connected to the 4-core and 5-core of the network port.

[0014] The second AC input terminal of the first rectifier bridge is connected to the second AC input terminal of the second rectifier bridge. The connection point serves as the second input terminal of the rectifier bridge unit and is connected to the 7-core and 8-core of the network port.

[0015] The first AC input terminal of the third rectifier bridge serves as the third input terminal of the rectifier bridge unit and is connected to the positive terminal of the external DC terminal.

[0016] The second AC input terminal of the third rectifier bridge serves as the fourth input terminal of the rectifier bridge unit and is connected to the negative terminal of the external DC terminal.

[0017] The first AC input terminal of the fourth rectifier bridge serves as the fifth input terminal of the rectifier bridge unit and is connected to the center tap of the transmission channel of the network transformer.

[0018] The second AC input terminal of the fourth rectifier bridge serves as the sixth input terminal of the rectifier bridge unit and is connected to the center tap of the receiving channel of the network transformer.

[0019] The DC positive output terminal of the first rectifier bridge, the DC positive output terminal of the second rectifier bridge, the DC positive output terminal of the third rectifier bridge, and the DC positive output terminal of the fourth rectifier bridge are connected, and the connection point serves as the output terminal of the rectifier bridge unit.

[0020] The DC negative output terminal of the first rectifier bridge and the DC negative output terminal of the third rectifier bridge are respectively connected to the network ground terminal;

[0021] The negative DC output terminal of the second rectifier bridge and the negative DC output terminal of the fourth rectifier bridge are respectively connected to the external DC terminal grounding terminal.

[0022] Optionally, in the power supply circuit described above, the first rectifier bridge is a silicon rectifier bridge.

[0023] Optionally, in the power supply circuit described above, the second rectifier bridge is a Schottky rectifier bridge.

[0024] Optionally, in the power supply circuit described above, the PD control unit includes: a PD protocol module, power supply control logic and current detection module, a first resistor and a first switching transistor;

[0025] The control port of the PD protocol module is connected to the control port of the power supply control logic and the current detection module. The connection point serves as the positive power supply voltage input terminal of the PD control unit and is connected to the output terminal of the rectifier bridge unit.

[0026] The first port of the power supply control logic and current detection module is connected to one end of the first resistor, and the connection point serves as the power ground port of the PD control unit.

[0027] The second port of the power supply control logic and current detection module is connected to the other end of the first resistor and the source of the first switching transistor;

[0028] The third port of the power supply control logic and current detection module is connected to the gate of the first switching transistor;

[0029] The drain of the first switching transistor serves as the signal ground port of the PD control unit.

[0030] Optionally, in the power supply circuit described above, the first switching transistor is a MOSFET.

[0031] Optionally, in the power supply circuit described above, the power-on delay unit includes: a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a Zener diode, a second switching transistor, and a driver;

[0032] One end of the second resistor is connected to one end of the third resistor, one end of the fourth resistor, and the source of the second switching transistor. The connection point serves as the first port of the power-on delay unit and is connected to the output terminal of the rectifier bridge unit.

[0033] The other end of the second resistor is connected to the cathode of the Zener diode, one end of the fifth resistor, and one end of the first capacitor, respectively, and the connection point is connected to the EN pin of the driver; the anode of the Zener diode is connected to the other end of the fifth resistor and the other end of the first capacitor, and the connection point is connected to the network ground terminal.

[0034] The other end of the third resistor is connected to the VIN pin of the driver;

[0035] The other end of the fourth resistor is connected to the gate of the second switch and one end of the sixth resistor;

[0036] The drain of the second switching transistor serves as the second port of the power-on delay unit and is connected to the first terminal of the power supply unit of the whole machine.

[0037] The other end of the sixth resistor is connected to the PG pin of the driver;

[0038] The GND pin of the driver serves as the third port of the power-on delay unit, and is connected to the input of the overcurrent protection unit and the second terminal of the power supply unit.

[0039] Optionally, in the power supply circuit described above, the second switching transistor is a MOSFET.

[0040] Optionally, in the power supply circuit described above, the overcurrent protection unit includes: a first diode and a second diode;

[0041] The anode of the first diode is connected to the anode of the second diode, and the connection point serves as the input terminal of the overcurrent protection unit.

[0042] The cathode of the first diode serves as the output terminal of the overcurrent protection unit;

[0043] The cathode of the second diode is connected to the ground terminal of the network port.

[0044] Optionally, in the above power supply circuit, the overall power supply unit includes: a second capacitor, a DC-DC power supply, and a CPU circuit;

[0045] One end of the second capacitor is connected to the first end of the DC-DC power supply, and the connection point serves as the first end of the overall power supply unit.

[0046] The other end of the second capacitor is connected to the second end of the DC-DC power supply, and the connection point serves as the second end of the overall power supply unit.

[0047] The control terminal of the DC-DC power supply is connected to the CPU circuit.

[0048] The power supply circuit provided in this application includes: a rectifier bridge unit, a PD control unit, a power-on delay unit, a complete power supply unit, an overcurrent protection unit, and a network transformer. The first and second input terminals of the rectifier bridge unit are connected to the corresponding wire cores of the network port. The third and fourth input terminals of the rectifier bridge unit are respectively connected to the positive and negative terminals of the external DC terminal. The fifth and sixth input terminals of the rectifier bridge unit are respectively connected to the corresponding center taps of the network transformer. The output terminals of the rectifier bridge unit are respectively connected to the PD control unit and the power-on delay unit. The overcurrent protection unit is located between the PD control unit and the power-on delay unit. The complete power supply unit is located after the power-on delay unit. The power supply circuit is compatible with standard PoE power supply, non-standard PoE power supply, and direct power supply from the external DC terminal. By adding an overcurrent protection unit, the normal operation of the overcurrent protection of the power supply circuit can be ensured. By adding a power-on delay unit, the influence of the filter capacitor in the power supply circuit on the protocol signal can be ensured. This solves the problem that existing non-standard PoE power supply and standard PoE power supply use the same wire pairs, resulting in incompatibility between standard PoE power supply and non-standard PoE power supply in the power supply circuit. Attached Figure Description

[0049] 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, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 This application provides a schematic diagram of the external terminal structure of a power supply circuit according to an embodiment of the present application.

[0051] Figure 2 This is a schematic diagram of a power supply circuit provided in an embodiment of this application;

[0052] Figure 3 A circuit diagram of a power supply circuit provided in an embodiment of this application;

[0053] Figure 4 This is a schematic diagram of a low-dropout linear regulator provided in an embodiment of this application;

[0054] Figure 5 A schematic diagram of the POE handshake signal current loop of a power supply circuit provided in an embodiment of this application;

[0055] Figure 6 A schematic diagram of a standard PoE power supply current loop for a power supply circuit provided in an embodiment of this application;

[0056] Figure 7A schematic diagram of a non-standard POE power supply current loop is provided for an embodiment of this application.

[0057] Figure 8 A handshake signal waveform diagram of a power supply circuit provided in an embodiment of this application;

[0058] Figure 9 A circuit diagram of another power supply circuit provided in an embodiment of this application. Detailed Implementation

[0059] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] First of all, it should be noted that, in combination Figure 1 The network cable is plugged into the RJ45 terminal for standard PoE power supply or non-standard PoE power supply; an external power supply is used via the DC terminal, such as... Figure 1 It is powered by the DC24V terminal.

[0061] There are three standard PoE power supply wiring sequences: data pair power supply (Alternative A), idle pair power supply (Alternative B), and mixed pair power supply (Alternative A + Alternative B). The operating conditions of each power supply wiring sequence are shown in Table 1-1:

[0062] Table 1-1 Standard PoE Power Supply Wiring Sequence and Operation Table

[0063]

[0064] Non-standard PoE power supply uses only 4 / 5 pairs or 7 / 8 pairs, and any pair can be + or -.

[0065] The advantages and disadvantages of standard PoE power supply, non-standard PoE power supply, and direct power supply from external DC terminals are shown in Table 1-2:

[0066] Table 1-2 Advantages and disadvantages of standard PoE power supply, non-standard PoE power supply, and direct power supply from external DC terminals.

[0067]

[0068] The inventors discovered that if the power supply circuit is compatible with the above three power supply methods, the following problems will be encountered: both non-standard PoE power supply and standard PoE power supply will use 4 / 5 pairs and 7 / 8 pairs for idle line pairs. If no processing is done, there will be incompatibility, that is, only one of the non-standard PoE power supply and standard PoE power supply idle line pairs can work normally.

[0069] In response to this, this application provides a power supply circuit to solve the problem that existing non-standard PoE power supplies and standard PoE power supplies use the same wire pairs, resulting in incompatibility between standard PoE power supplies and non-standard PoE power supplies in the power supply circuit.

[0070] First of all, it should be noted that the power supply circuit provided in this application is a power supply structure for the network port and DC power socket commonly used in electronic products. Its main purpose is to solve the problem of incompatibility between standard PoE power supply and non-standard PoE power supply.

[0071] Please see Figure 2 The power supply circuit mainly includes: rectifier bridge unit 101, PD control unit 102, power-on delay unit 103, whole machine power supply unit 104, overcurrent protection unit 105 and network transformer TI.

[0072] The first and second input terminals of the rectifier bridge unit 101 are connected to the corresponding wire cores of the network port. The third and fourth input terminals of the rectifier bridge unit 101 are connected to the positive and negative terminals of the external DC terminal, respectively. The fifth and sixth input terminals of the rectifier bridge unit 101 are connected to the center taps of the network transformer TI, respectively. The output terminals of the rectifier bridge unit 101 are connected to the PD control unit 102 and the power-on delay unit 103, respectively. The overcurrent protection unit 105 is placed between the PD control unit 102 and the power-on delay unit 103. The power supply unit 104 is placed after the power-on delay unit 103.

[0073] In practical applications, a network port is the port of an Ethernet cable, which consists of 8 wires, named 1 to 8. The network port can be connected to an Ethernet cable via an RJ45 connector or other existing standardized physical network interface connectors, all of which are within the scope of this application.

[0074] The external DC terminal can be powered by connecting to an external power source. Specifically, the positive terminal of the external DC terminal is connected to the positive terminal of the external power source, and the negative terminal is connected to the negative terminal of the external DC terminal. For example, the external DC terminal can be... Figure 1 DC24V terminal.

[0075] In some embodiments, such as Figure 3 As shown, the rectifier bridge unit 101 mainly includes: a first rectifier bridge D3, a second rectifier bridge D4, a third rectifier bridge D5, and a fourth rectifier bridge D6.

[0076] The first AC input terminal of the first rectifier bridge D3 is connected to the first AC input terminal of the second rectifier bridge D4. This connection point serves as the first input terminal of rectifier bridge unit 101, connecting to wires 4 and 5 of the network port. The second AC input terminal of the first rectifier bridge D3 is connected to the second AC input terminal of the second rectifier bridge D4. This connection point serves as the second input terminal of rectifier bridge unit 101, connecting to wires 7 and 8 of the network port. The first AC input terminal of the third rectifier bridge D5 serves as the third input terminal of rectifier bridge unit 101, connecting to the positive terminal of an external DC terminal. The second AC input terminal of the third rectifier bridge D5 serves as the fourth input terminal of rectifier bridge unit 101, connecting to the negative terminal of an external DC terminal. The first AC input terminal of the fourth rectifier bridge D6 serves as the fifth input terminal of rectifier bridge unit 101. The input terminal is connected to the center tap A of the transmitting channel of the network transformer TI; the second AC input terminal of the fourth rectifier bridge D6 serves as the sixth input terminal of the rectifier bridge unit 101 and is connected to the center tap B of the receiving channel of the network transformer TI; the DC positive output terminals of the first rectifier bridge D3, the second rectifier bridge D4, the third rectifier bridge D5, and the fourth rectifier bridge D6 are connected, and the connection point serves as the output terminal of the rectifier bridge unit 101; the DC negative output terminals of the first rectifier bridge D3 and the third rectifier bridge D5 are respectively connected to the network port ground terminal GND1; the DC negative output terminals of the second rectifier bridge D4 and the fourth rectifier bridge D6 are respectively connected to the external DC terminal ground terminal GND2.

[0077] In practical applications, the first rectifier bridge D3 can be a silicon rectifier bridge, and the second rectifier bridge D4 can be a Schottky rectifier bridge.

[0078] In some embodiments, such as Figure 3 As shown, the PD control unit 102 mainly includes: a PD protocol module, a power supply control logic and current detection module, a first resistor R0 and a first switching transistor K0.

[0079] The control port of the PD protocol module is connected to the control port of the power supply control logic and the current detection module. The connection point serves as the positive power supply voltage input terminal of the PD control unit 102 and is connected to the output terminal of the rectifier bridge unit 101. The first port of the power supply control logic and the current detection module is connected to one end of the first resistor R0, and the connection point serves as the power ground port GND_o of the PD control unit 102. The second port of the power supply control logic and the current detection module is connected to the other end of the first resistor R0 and the source of the first switching transistor K0. The third port of the power supply control logic and the current detection module is connected to the gate of the first switching transistor K0. The drain of the first switching transistor K0 serves as the signal ground port GND_i of the PD control unit 102.

[0080] In practical applications, the first switching transistor K0 can be a MOSFET; of course, it is not limited to this and can also be other existing types of switching transistors. This application does not make specific limitations on them, and they are all within the protection scope of this application.

[0081] In a PoE power supply system, the entire power supply system consists of: Power Sourcing Equipment (PSE), Powered Devices (PDs), links, and related detection modules. Power Sourcing Equipment, such as PoE switches and PoE injectors, is responsible for providing power to the network cable. Powered Devices are devices that receive power, such as wireless access points (APs), network cameras, IP phones, and IoT devices. Links refer to Ethernet cables (twisted pairs). Related detection modules include power control logic and current detection modules.

[0082] The PD protocol module is an independent circuit module in a PoE power supply system. It is usually integrated into the device that requires PoE power, and its main functions are:

[0083] ①Detection and Classification: "Handshake" with the power supply equipment to confirm that it is a standard PD device and inform the other party of its required power level.

[0084] ② Rectification and voltage regulation: Receive DC power from the 4 or 2 twisted pairs of the network cable and convert it into the low voltage required by the internal circuitry of the device (such as the motherboard and chips).

[0085] ③ Isolation and protection: Ensure that data signals and power supply are isolated from each other to prevent interference, and provide overcurrent and overvoltage protection.

[0086] The power supply control logic and current detection module is an independent circuit module in the PoE power supply system. Its main function is to control the power supply logic and output current detection of the PoE power supply system.

[0087] It should be noted that in practice, the PD protocol module, power supply control logic and current detection module, first resistor R0 and first switch K0 can be integrated into a single IC. An example is the general-purpose PD control IC, model MP8001.

[0088] In some embodiments, such as Figure 3 As shown, the power-on delay unit 103 mainly includes: a second resistor R1, a third resistor R2, a fourth resistor R3, a fifth resistor R5, a sixth resistor R4, a first capacitor C1, a Zener diode ZD2, a second switching transistor K1, and a driver LDO.

[0089] One end of the second resistor R1 is connected to one end of the third resistor R2, one end of the fourth resistor R3, and the source of the second switching transistor K1. This connection point serves as the first port of the power-on delay unit 103, which is connected to the output terminal of the rectifier bridge unit 101. The other end of the second resistor R1 is connected to the cathode of the Zener diode ZD2, one end of the fifth resistor R5, and one end of the first capacitor C1. This connection point is connected to the EN pin of the driver LDO. The anode of the Zener diode ZD2 is connected to the other end of the fifth resistor R5 and the other end of the first capacitor C1. This connection point is connected to the network ground terminal GND. 1; The other end of the third resistor R2 is connected to the VIN pin of the driver LDO; the other end of the fourth resistor R3 is connected to the gate of the second switch K1 and one end of the sixth resistor R4; the drain of the second switch K1 serves as the second port of the power-on delay unit 103 and is connected to the first end of the power supply unit 104; the other end of the sixth resistor R4 is connected to the PG pin of the driver LDO; the GND pin of the driver LDO serves as the third port of the power-on delay unit 103 and is connected to the input of the overcurrent protection unit 105 and the second end of the power supply unit 104.

[0090] In practical applications, the second switch K1 can be a MOSFET; of course, it is not limited to this and can also be other existing types of switch transistors. This application does not make specific limitations on them, and they are all within the protection scope of this application.

[0091] The driver LDO can be a low-dropout regulator (LDO) with high voltage and low quiescent current. For example, it could be... Figure 4 The model shown is NDP6802, a low dropout linear regulator. When the EN pin of the low dropout linear regulator is turned off, the quiescent current is <1.5uA, the operating voltage is up to 85V, and it can meet the POE48V withstand voltage requirement.

[0092] The power-on delay unit 103 consists of a second resistor R1, a third resistor R2, a fourth resistor R3, a fifth resistor R5, a sixth resistor R4, a first capacitor C1, a Zener diode ZD2, a second switching transistor K1, and a driver LDO. The threshold of the EN pin of the driver LDO is 3.5V. The second resistor R1 can be a megohm-level resistor. By selecting appropriate values ​​for the fifth resistor R5 and the first capacitor C1, the delay parameters that match the power supply circuit can be obtained. The control terminal of the driver LDO is output through the PG pin, which directly controls the on / off state of the second switching transistor K1. The Zener diode ZD2 is used for voltage limiting protection of the EN pin of the driver LDO.

[0093] In some embodiments, such as Figure 3 As shown, the overcurrent protection unit 105 mainly includes: a first diode D1 and a second diode D2.

[0094] The anode of the first diode D1 is connected to the anode of the second diode D2, and the connection point serves as the input terminal of the overcurrent protection unit 105; the cathode of the first diode D1 serves as the output terminal of the overcurrent protection unit 105; and the cathode of the second diode D2 is connected to the network ground terminal GND1.

[0095] In practical applications, the first diode D1 and the second diode D2 are the same type of diode. This ensures that during standard PoE power supply, the current return path passes through the first diode D1 back to the first switch K0 and the first resistor R0 in the PD control unit 102, thereby ensuring the normal operation of the overcurrent protection function of the PD control unit 102. For example, the first diode D1 and the second diode D2 can be silicon diodes.

[0096] Specifically, the first diode D1 is the protection diode of the PD control unit 102. The current can be selected to flow back from either the first diode D1 or the second diode D2. In order to ensure that the current flows back from the first diode D1 in certain situations, a second diode D2 of the same type is added to balance the voltage drop.

[0097] In some embodiments, such as Figure 3 As shown, the power supply unit 104 mainly includes: a second capacitor C2, a DC-DC power supply, and a CPU circuit;

[0098] One end of the second capacitor C2 is connected to the first terminal of the DC-DC power supply, and the connection point serves as the first terminal of the power supply unit 104; the other end of the second capacitor C2 is connected to the second terminal of the DC-DC power supply, and the connection point serves as the second terminal of the power supply unit 104; the control terminal of the DC-DC power supply is connected to the CPU circuit.

[0099] In practical applications, the output of the DC-DC power supply is controlled by the CPU circuit, and the second capacitor C2 is a filter capacitor.

[0100] In the Power over Ethernet (PoE) standard, electronic devices plugged into the PoE switch's network port request power from the PoE switch via protocol signals. To avoid the filter capacitors in the power supply unit 104 affecting the protocol signals, a power-on delay unit 103 can be designed before the power supply unit 104 to ensure the PoE protocol completes its operation. Alternatively, the power-on delay unit 103 can be designed for ultra-low power consumption to avoid interfering with the 10mA signal emitted by the power supply end to detect whether the powered end supports PoE.

[0101] based on Figure 3 The power supply circuit shown operates as follows when used to implement standard PoE power supply:

[0102] For power supply of data pairs, power supply of idle pairs, and power supply of mixed pairs, there are two circuit loops: the POE handshake signal current loop and the standard POE power supply current loop.

[0103] For the PoE handshake signal current loop, after initial power-on, it converges through the second rectifier bridge D4 and the fourth rectifier bridge D6 before reaching the PD control unit 102 (the first switch K0 in the PD control unit 102 is off during the initial power-on phase). Figure 5 As shown.

[0104] For standard PoE power supply current loops, such as Figure 6 As shown, the second rectifier bridge D4 can be a Schottky rectifier bridge, and the fourth rectifier bridge D6 can be a Schottky or silicon rectifier bridge (in the non-standard POE power supply current loop, the first rectifier bridge D3 is a silicon rectifier bridge, and the voltage drops produced by the two are different. For example, in the datasheet of the Schottky rectifier bridge KMB220F, the voltage drop of 1A is 0.7V, and in the datasheet of the silicon rectifier bridge MB2S, the voltage drop of 1A is 1.1V. The current will select the loop with the smaller voltage drop, that is, the standard POE power supply current loop returns to the first diode D1, and through the first switching transistor K0 and the first resistor R0 in the PD control unit 102, the overcurrent protection is ensured to work normally.

[0105] If the second rectifier bridge D4 and the fourth rectifier bridge D6 are of the same type, the current will be diverted from the non-standard POE power supply current loop, and the current protection function in the PD control unit 102 will fail.

[0106] based on Figure 3 The power supply circuit shown operates as follows when used to implement non-standard PoE power supply:

[0107] After initial power-on, the current flows through the first rectifier bridge D3 to the power-on delay unit 103, then through the second diode D2 back to the ground terminal of the RJ45 interface, forming a non-standard PoE power supply current loop. Figure 7 As shown.

[0108] against Figure 6 The DC power supply is provided by the 4 / 5 and 7 / 8 pairs of the RJ45 terminal. After passing through the third rectifier bridge D5, the power-on delay unit 103, and the power supply unit 104, it returns to the network ground terminal GND1 through the second diode D2. At this time, the VCC pin and GND_i pin of the PD control unit 102 are connected to the power supply. It was found that without the protection of the first diode D1, the current would flow into the VCC pin and out of the GND_i pin, causing the PD control unit 102 to generate abnormal heat.

[0109] Combination Figure 5 and Figure 7After initial power-on, the PoE switch sends a handshake signal via 1 / 2-pair, 3 / 6-pair, or 4 / 5-pair, 7 / 8-pair (the waveform of the handshake signal is shown in Figure 1). Figure 8 As shown in the figure, the horizontal axis represents the total signal time, and the vertical axis represents the signal voltage. The signal reaches the PD control unit 102. Since wire pairs 4 / 5 and 7 / 8 also belong to the non-standard PoE power supply current loop, the handshake signal will also reach the power-on delay unit 103 on the non-standard PoE power supply current loop. By selecting appropriate second resistor R1 and first capacitor C1, the delay time of the delay switch unit can be made greater than... Figure 8 The total time of the signal waveform shown is such that the second switch K1 is turned off during the delay time; because during the detection phase, the PoE switch sends a test voltage signal to the device connected to the port ( Figure 8 During the Detection Period phase, the system detects the presence of a specific common-mode resistance (typically 24.9kΩ). Therefore, the power-on delay unit 103 is designed to be low-power, equivalent to a high-impedance load connected in parallel with the common-mode resistance, ensuring that the error caused by the detected common-mode resistance is within acceptable limits. When communication is complete (i.e., ...), the system... Figure 8 After a successful handshake (signal waveform), the PoE switch outputs 48V power through parallel connections of wire pairs 1 / 2, 3 / 6 and 4 / 5, 7 / 8. The first switch K0 in the general-purpose control PD control unit 102 is turned on, and the current loop is completed. Since wire pairs 4 / 5 and 7 / 8 belong to both the non-standard PoE power supply current loop and the third current loop, the current will select the loop with the smaller voltage drop.

[0110] based on Figure 3 The power supply circuit shown operates as follows when it is used to directly supply power from an external DC power supply terminal:

[0111] The DC power supply is input from the external power supply DC terminal, and returns to the network ground terminal GND1 through the third rectifier bridge D5, the power-on delay unit 103, the whole power supply unit 104 and the second diode D2 in the overcurrent protection unit 105.

[0112] The power supply circuit provided in this embodiment includes: a rectifier bridge unit 101, a PD control unit 102, a power-on delay unit 103, a power supply unit 104, an overcurrent protection unit 105, and a network transformer TI; the first and second input terminals of the rectifier bridge unit 101 are connected to the corresponding wire cores of the network port, the third and fourth input terminals of the rectifier bridge unit 101 are respectively connected to the positive and negative terminals of the external DC terminal, and the fifth and sixth input terminals of the rectifier bridge unit 101 are respectively connected to the center taps of the network transformer TI; the output terminals of the rectifier bridge unit 101 are respectively connected to the PD control unit 102 and the power-on delay unit 103; the overcurrent protection unit 105 is placed between the PD control unit 102 and the power-on delay unit 103; and the power supply unit 104 is placed after the power-on delay unit 103. The power supply circuit is compatible with standard PoE power supply, non-standard PoE power supply and direct power supply from external DC terminals. The addition of overcurrent protection unit 105 ensures normal operation of overcurrent protection in the power supply circuit, while the addition of power-on delay unit 103 ensures the effect of filter capacitor in power supply circuit on protocol signal. This solves the problem that existing non-standard PoE power supply and standard PoE power supply use the same wire pairs, resulting in incompatibility between standard PoE power supply and non-standard PoE power supply in the power supply circuit.

[0113] It should be noted that when the power supply circuit only supports standard PoE power supply and non-standard PoE power supply, the corresponding circuit diagram is as follows: Figure 9 As shown. Among them, the power-on delay unit 103 can be composed of the second switching transistor K1 and the power-on delay circuit, and the power supply unit 104 can be composed of the second capacitor C2 and the main circuit.

[0114] It is worth noting that the power supply circuit provided in this application supports standard PoE power supply, non-standard PoE power supply, and direct power supply from external DC terminals. It can meet the needs of customers for various electronic products, as well as electronic products for civilian security and intelligent buildings. It can also meet the different power supply needs that may arise from on-site construction conditions, cost requirements, and performance requirements. This achieves the goal of ensuring that the product can be compatible with all needs in order to meet the production and management cost requirements of enterprises, so that one solution can meet all scenarios and avoid the problem of increased management costs caused by multiple versions.

[0115] The features described in the various embodiments of this specification can be substituted for or combined with each other. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0116] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0117] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0118] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A power supply circuit, characterized in that, include: The system includes a rectifier bridge unit, a PD control unit, a power-on delay unit, a power supply unit, an overcurrent protection unit, and a network transformer. The first and second input terminals of the rectifier bridge unit are connected to the corresponding wire cores of the network port. The third and fourth input terminals of the rectifier bridge unit are respectively connected to the positive and negative terminals of the external DC terminal. The fifth and sixth input terminals of the rectifier bridge unit are respectively connected to the center taps of the network transformer. The output terminals of the rectifier bridge unit are respectively connected to the PD control unit and the power-on delay unit; The overcurrent protection unit is located between the PD control unit and the power-on delay unit; The power supply unit is located after the power-on delay unit.

2. The power supply circuit according to claim 1, characterized in that, The rectifier bridge unit includes: a first rectifier bridge, a second rectifier bridge, a third rectifier bridge, and a fourth rectifier bridge; The first AC input terminal of the first rectifier bridge is connected to the first AC input terminal of the second rectifier bridge, and the connection point serves as the first input terminal of the rectifier bridge unit, which is connected to the 4-core and 5-core of the network port. The second AC input terminal of the first rectifier bridge is connected to the second AC input terminal of the second rectifier bridge. The connection point serves as the second input terminal of the rectifier bridge unit and is connected to the 7-core and 8-core of the network port. The first AC input terminal of the third rectifier bridge serves as the third input terminal of the rectifier bridge unit and is connected to the positive terminal of the external DC terminal. The second AC input terminal of the third rectifier bridge serves as the fourth input terminal of the rectifier bridge unit and is connected to the negative terminal of the external DC terminal. The first AC input terminal of the fourth rectifier bridge serves as the fifth input terminal of the rectifier bridge unit and is connected to the center tap of the transmission channel of the network transformer. The second AC input terminal of the fourth rectifier bridge serves as the sixth input terminal of the rectifier bridge unit and is connected to the center tap of the receiving channel of the network transformer. The DC positive output terminal of the first rectifier bridge, the DC positive output terminal of the second rectifier bridge, the DC positive output terminal of the third rectifier bridge, and the DC positive output terminal of the fourth rectifier bridge are connected, and the connection point serves as the output terminal of the rectifier bridge unit. The DC negative output terminal of the first rectifier bridge and the DC negative output terminal of the third rectifier bridge are respectively connected to the network ground terminal; The negative DC output terminal of the second rectifier bridge and the negative DC output terminal of the fourth rectifier bridge are respectively connected to the external DC terminal grounding terminal.

3. The power supply circuit according to claim 2, characterized in that, The first rectifier bridge is a silicon rectifier bridge.

4. The power supply circuit according to claim 2, characterized in that, The second rectifier bridge is a Schottky rectifier bridge.

5. The power supply circuit according to claim 1, characterized in that, The PD control unit includes: a PD protocol module, a power supply control logic and current detection module, a first resistor and a first switching transistor; The control port of the PD protocol module is connected to the control port of the power supply control logic and the current detection module. The connection point serves as the positive power supply voltage input terminal of the PD control unit and is connected to the output terminal of the rectifier bridge unit. The first port of the power supply control logic and current detection module is connected to one end of the first resistor, and the connection point serves as the power ground port of the PD control unit. The second port of the power supply control logic and current detection module is connected to the other end of the first resistor and the source of the first switching transistor; The third port of the power supply control logic and current detection module is connected to the gate of the first switching transistor; The drain of the first switching transistor serves as the signal ground port of the PD control unit.

6. The power supply circuit according to claim 5, characterized in that, The first switching transistor is a MOSFET.

7. The power supply circuit according to claim 1, characterized in that, The power-on delay unit includes: a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a Zener diode, a second switching transistor, and a driver; One end of the second resistor is connected to one end of the third resistor, one end of the fourth resistor, and the source of the second switching transistor. The connection point serves as the first port of the power-on delay unit and is connected to the output terminal of the rectifier bridge unit. The other end of the second resistor is connected to the cathode of the Zener diode, one end of the fifth resistor, and one end of the first capacitor, respectively, and the connection point is connected to the EN pin of the driver; the anode of the Zener diode is connected to the other end of the fifth resistor and the other end of the first capacitor, and the connection point is connected to the network ground terminal. The other end of the third resistor is connected to the VIN pin of the overcurrent protection power supply driver; The other end of the fourth resistor is connected to the gate of the second switch and one end of the sixth resistor; The drain of the second switching transistor serves as the second port of the power-on delay unit and is connected to the first terminal of the power supply unit of the whole machine. The other end of the sixth resistor is connected to the PG pin of the driver; The GND pin of the driver serves as the third port of the power-on delay unit, and is connected to the input of the overcurrent protection unit and the second terminal of the power supply unit.

8. The power supply circuit according to claim 7, characterized in that, The second switch is a MOSFET.

9. The power supply circuit according to claim 1, characterized in that, The overcurrent protection unit includes: a first diode and a second diode; The anode of the first diode is connected to the anode of the second diode, and the connection point serves as the input terminal of the overcurrent protection unit. The cathode of the first diode serves as the output terminal of the overcurrent protection unit; The cathode of the second diode is connected to the ground terminal of the network port.

10. The power supply circuit according to claim 1, characterized in that, The power supply unit of the whole machine includes: a second capacitor, a DC-DC power supply and a CPU circuit; One end of the second capacitor is connected to the first end of the DC-DC power supply, and the connection point serves as the first end of the overall power supply unit. The other end of the second capacitor is connected to the second end of the DC-DC power supply, and the connection point serves as the second end of the overall power supply unit. The control terminal of the DC-DC power supply is connected to the CPU circuit.

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