Power supply control circuit and load power supply device

Abstract

The utility model provides power supply control circuit and load power supply device, power supply control circuit includes: first power supply branch, second power supply branch and isolation switching module, first power supply input end of first power supply branch is configured as coupling DC power supply circuit, first power supply output end is coupled first power supply negative voltage end through first electric capacity, second power supply input end of second power supply branch is coupled second power supply negative voltage end through second electric capacity, and is configured as coupling POE power supply circuit, second power supply output end is coupled to first power supply negative voltage end through first electric capacity, and is configured as coupling to load device. When POE power supply is disconnected or network is dropped, isolation switching module cuts off POE ground wire immediately, and DC power supply circuit restores power supply path automatically, and load device keeps normal operation. This embodiment can realize automatic switching between POE power supply and DC power supply, avoids power supply interruption in switching moment, and ensures the continuous operation of load equipment.

Description

Technical Field

[0001] This utility model relates to the field of strobe light technology, and in particular to a power supply control circuit and a load power supply device. Background Technology

[0002] In some scenarios, the load device can be powered by either DC (Direct Current) or PoE (Power over Ethernet) power. However, a single power supply mode is highly susceptible to device shutdown during power outages, posing a significant reliability risk.

[0003] Even with a redundant design that uses both DC and PoE power supplies, the related technology still has the problem of brief power outages for the load equipment during the switching between the two power sources.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this utility model, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0005] In view of the problems in the prior art, the purpose of this utility model is to provide a power supply control circuit and a load power supply device, which overcomes the difficulties of the prior art and can solve the technical problem of temporary power loss of load equipment during the switching between two power sources.

[0006] The first aspect of this disclosure provides a power supply control circuit, which includes: a first power supply branch, a second power supply branch, and an isolation switching module; The first power supply branch has a first power supply input terminal and a first power supply output terminal. The first power supply input terminal is configured to be coupled to a DC power supply circuit, and the first power supply output terminal is coupled to a first power supply negative voltage terminal through a first capacitor and is configured to be coupled to a load device. The second power supply branch has a second power supply input terminal and a second power supply output terminal. The second power supply input terminal is coupled to the second power supply negative voltage terminal through a second capacitor and is configured to be coupled to the POE power supply circuit. The second power supply output terminal is coupled to the first power supply negative voltage terminal through a first capacitor and is configured to be coupled to the load device. The isolation switching module is coupled between the first negative power supply terminal and the second negative power supply terminal, and is configured as follows: The first level signal controls the cutoff, disconnecting the first and second negative voltage terminals of the power supply. The POE power supply circuit charges the second capacitor, and the DC power supply circuit supplies power through the first power supply branch. It is turned on by the second level signal, connecting the first negative voltage terminal and the second negative voltage terminal of the power supply. The POE power supply circuit is powered through the second power supply branch. When the POE power supply circuit is powered off, triggering the second level signal to change to the first level signal, it cuts off and switches to the DC power supply circuit, which supplies power through the first power supply branch.

[0007] Optionally, the first power supply branch includes a first diode, the positive terminal of which is coupled to the first power supply input terminal and the negative terminal is connected to the first power supply output terminal; The second power supply branch includes a second diode, the positive terminal of which is coupled to the first node between the second power supply input terminal and the second capacitor, and the negative terminal is coupled to the second power supply output terminal.

[0008] Optionally, the isolation switching module includes: a switching element, which is connected to a control signal terminal via a control terminal, coupled to a first negative power supply terminal via a first signal terminal, and coupled to a second negative power supply terminal via a second signal terminal.

[0009] Optionally, the switching element is a MOSFET, a thyristor, or a relay.

[0010] Optionally, the isolation switching module also includes: The third diode has its positive terminal connected to the second node and its negative terminal connected to the third node. The second node is located between the second power supply negative voltage terminal and the second signal terminal, and the third node is located between the control terminal and the control signal terminal.

[0011] Optionally, the isolation switching module also includes: An RC soft-start circuit is coupled between the control terminal and the first signal terminal.

[0012] A second aspect of this disclosure provides a load power supply device, comprising: DC power supply circuit; PoE power supply circuit; The power supply control circuit of any of the above embodiments; The output of the DC power supply circuit is coupled to the first power supply input, and the output of the POE power supply circuit is coupled to the second power supply input.

[0013] Optionally, the DC power supply circuit includes a DC soft-start circuit, configured to be coupled to the first power supply input terminal via the DC soft-start circuit.

[0014] Optionally, the PoE power supply circuit includes a PD control circuit, which is connected to the control terminal of the isolation switching module and is used to input a first-level signal and a second-level signal to the isolation switching module.

[0015] Optionally, surge protection units are respectively provided at the front end of the first power input terminal and the second power input terminal.

[0016] The power supply control circuit and load power supply device provided in this disclosure have the following beneficial effects: The isolation switching module is coupled between the first negative voltage terminal and the second negative voltage terminal and is configured to: be cut off by a first level signal, disconnecting the first negative voltage terminal and the second negative voltage terminal, allowing the POE power supply circuit to charge the second capacitor and the DC power supply circuit to be powered through the first power supply branch; be turned on by a second level signal, connecting the first negative voltage terminal and the second negative voltage terminal, allowing the POE power supply circuit to be powered through the second power supply branch; and be cut off when the POE power supply circuit is de-energized, triggering the second level signal to change to the first level signal, switching the DC power supply circuit to be powered through the first power supply branch.

[0017] During the operation of the load device, when both the DC power supply circuit and the PoE power supply circuit are connected simultaneously, the PoE power supply circuit typically has a higher output voltage, while the DC power supply circuit has a lower voltage. Therefore, under normal operating conditions, the PoE power supply circuit supplies power to the load device through the second power supply branch. When the PoE power supply is disconnected or the network goes offline, the isolation switching module immediately disconnects the PoE ground wire (the negative voltage terminal of the second power supply), and the DC power supply circuit automatically restores its power supply path, allowing the load device to continue operating normally.

[0018] Through the above technical solution, this embodiment can utilize the isolation switching module to control the connection between the first negative voltage terminal and the second negative voltage terminal of the power supply, and combine the coupling effect between the second capacitor and the second negative voltage terminal of the power supply to achieve electrical isolation and controlled connection between the DC power supply circuit and the POE power supply circuit during power-on and switching processes. Thus, when the POE power supply circuit completes the handshake to establish power supply or the DC power supply circuit is in an effective power supply state, automatic power supply switching between the two power sources can be achieved, avoiding power interruption at the moment of switching and ensuring the continuous operation of the load equipment.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0020] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0021] Figure 1 A schematic diagram of a power supply control circuit provided in this disclosure is shown. Figure 2 exhibit Figure 1 The topology diagram of the power supply control circuit is shown below. Figure 3 This invention discloses an architectural diagram of a load power supply device according to an embodiment of the present invention. Figure 4 exhibit Figure 3 The topology diagram of the DC power supply circuit in the load power supply device shown. Figure 5 exhibit Figure 3 The diagram shows the topology of the PoE power supply circuit in the load power supply device. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0023] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0024] Furthermore, the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to define the order of functions performed by these devices, modules or units or their interdependencies.

[0025] In related technologies, the power failure of load devices stems from voltage instability during the PoE protocol handshake phase or transient interference when DC power is connected, which in turn causes power outages to the load devices, affecting their operational stability. This is especially serious in high-reliability scenarios such as fire protection, power supply, and border areas.

[0026] This disclosure provides a technical solution that enables seamless, power-loss-free switching between DC and PoE power supplies to improve the operational robustness of load devices and system security.

[0027] Figure 1 This illustration shows a schematic diagram of a power supply control circuit according to an embodiment of the present disclosure, such as... Figure 1 As shown, the power supply control circuit includes a first power supply branch 110, a second power supply branch 120, and an isolation switching module 200.

[0028] The first power supply branch 110 has a first power supply input terminal IN1 and a first power supply output terminal OUT1. The first power supply input terminal IN1 is configured to be coupled to the DC power supply circuit 400 to receive DC power supply signals. The first power supply output terminal OUT1 is connected to the first negative power supply terminal DC_GND through the first capacitor C17 to provide potential buffering and filter transient interference during power supply. It is also configured to be coupled to the load device 300 to output a stable operating voltage to the load device 300.

[0029] The second power supply branch 120 has a second power supply input terminal IN2 and a second power supply output terminal OUT2. The second power supply input terminal IN2 is coupled to the second power supply negative voltage terminal POE_GND through a second capacitor C16, which is used for energy storage and potential stabilization. The second power supply input terminal IN2 is also configured to be coupled to the POE power supply circuit 500 for receiving Ethernet power supply signals. The second power supply output terminal OUT2 is coupled to the first power supply negative voltage terminal DC_GND through a first capacitor C17, thereby electrically isolating the potential between the first power supply branch 110 and the second power supply branch 120, and is also configured to be coupled to the load device 300.

[0030] The above structure enables independent coupling between the DC power supply path (first power supply branch 110) and the POE power supply path (second power supply branch 120), thus avoiding direct conflict or mutual interference between the two power supplies when switching power supplies.

[0031] The isolation switching module 200 is coupled between the first negative voltage terminal DC_GND and the second negative voltage terminal POE_GND. The isolation switching module 200 is configured to switch the on or off state between the first negative voltage terminal DC_GND and the second negative voltage terminal POE_GND under the control of different level signals, so as to realize the dynamic switching of the two power supplies.

[0032] When the isolation switching module 200 receives the first level signal, the first negative power supply terminal DC_GND and the second negative power supply terminal POE_GND are disconnected. At this time, the loop between the second power supply branch 120 and the load device 300 is not connected, the POE power supply circuit 500 does not provide power to the load, while the DC power supply circuit 400 continuously supplies power to the load through the first power supply branch 110. Simultaneously, the POE power supply circuit 500 charges the second capacitor C16 through the second power supply input terminal IN2 to complete the detection and handshake of the power supply protocol.

[0033] After the PoE power supply circuit 500 completes power supply negotiation, the first level signal changes to the second level signal. The isolation switching module 200 responds to the second level signal and turns on, connecting the first negative power supply terminal DC_GND with the second negative power supply terminal POE_GND. At this time, the second power supply branch 120 forms a complete power supply loop, and the PoE power supply circuit 500 supplies power to the load device 300 through this second power supply branch 120, realizing the switch from DC power supply mode to PoE power supply mode. During this switching process, the power supply voltage remains continuous, and the power supply process is smooth and uninterrupted.

[0034] When the PoE power supply circuit 500 loses power or detects a power supply abnormality, the control signal of the isolation switching module 200 changes from a second-level signal to a first-level signal. In response to the level change, the isolation switching module 200 disconnects the first negative power supply terminal DC_GND from the second negative power supply terminal POE_GND, thereby switching the DC power supply circuit 400 to continue supplying power to the load device 300 through the first power supply branch 110, ensuring a continuous and stable power supply to the load side.

[0035] During the operation of the load device 300, when the DC power supply circuit 400 and the PoE power supply circuit 500 are connected simultaneously, the PoE power supply circuit 500 typically has a higher output voltage (e.g., 48V), while the DC power supply circuit 400 has a lower voltage (e.g., 36V). Therefore, under normal operating conditions, the PoE power supply circuit 500 supplies power to the load device 300 through the second power supply branch 120. When the PoE power supply is disconnected or the network goes offline, the isolation switching module 200 immediately disconnects the PoE ground wire (the second power supply negative voltage terminal POE_GND), the DC power supply circuit 400 automatically restores its power supply path, and the load device 300 continues to operate normally.

[0036] Through the above technical solution, this embodiment can utilize the controlled connection between the first power supply negative voltage terminal DC_GND and the second power supply negative voltage terminal POE_GND by the isolation switching module 200, and combine the coupling effect between the second capacitor C16 and the second power supply negative voltage terminal POE_GND to achieve electrical isolation and controlled connection between the DC power supply circuit and the POE power supply circuit during power-on and switching processes. Thus, when the POE power supply circuit completes the handshake to establish power supply or the DC power supply circuit is in an effective power supply state, automatic power supply switching between the two power sources can be achieved, avoiding power interruption at the moment of switching and ensuring the continuous operation of the load equipment.

[0037] Therefore, this implementation eliminates the switching power failure problem in the POE and DC dual power supply redundancy design, improving the reliability and safety of video surveillance and fire protection equipment under abnormal power supply conditions.

[0038] Figure 2 exhibit Figure 1 The topology diagram of the power supply control circuit shown is as follows: Figure 2 As shown, diodes D15 and D16 are respectively installed in the first power supply branch 110 and the second power supply branch 120 to achieve unidirectional conduction.

[0039] like Figure 2 As shown, the first power supply branch 110 includes a first diode D15. The anode A of the first diode D15 is coupled to the first power supply input terminal IN1, and the cathode K is coupled to the first power supply output terminal OUT1. Through the first diode D15, it can be ensured that the electrical energy input from the DC power supply circuit 400 flows unidirectionally to the load device 300 only along the first power supply branch 110, preventing the voltage on the load device 300 side from flowing back to the DC power supply circuit 400.

[0040] The second power supply branch 120 includes a second diode D16. The anode A of the second diode D16 is coupled to the first node N1 between the second power supply input terminal IN2 and the second capacitor C16, and the cathode is coupled to the second power supply output terminal OUT2. Through the second diode D16, it can be ensured that the power output by the POE power supply circuit 500 flows unidirectionally to the load device 300 only along the second power supply branch 120, preventing the voltage on the load device 300 side from flowing back to the first node N1 and the POE power supply circuit 500.

[0041] By installing diodes D15 and D16 in the two power supply branches mentioned above, this implementation effectively controls the power supply direction, ensuring that electrical energy flows in only one direction during the switching between DC power supply and POE power supply, thereby preventing direct conflict between the two power sources. Combined with the control logic of the isolation switching module 200, the load device 300 can obtain a continuous and stable power supply when the isolation switching module 200 is turned on or off, with a smooth switching process without interruptions.

[0042] Optionally, the first diode D15 and the second diode D16 can be implemented using various unidirectional diodes (such as Schottky diodes, fast recovery diodes, etc.), and the specific type of diode does not constitute a limitation on the scope of protection of this disclosure.

[0043] In this disclosure, such as Figure 2 As shown, the isolation switching module 200 includes a switching element 21, which can be controlled by a MOSFET Q3 to achieve ground connection control. The control terminal G of Q3 is coupled to the control signal terminal CTRL, the first signal terminal D is coupled to the first negative voltage terminal DC_GND of the first power supply branch 110, and the second signal terminal S is coupled to the second negative voltage terminal POE_GND.

[0044] In this embodiment, when the control signal terminal CTRL outputs a first-level signal, Q3 is turned off, thereby disconnecting the conduction path between DC_GND and POE_GND; when the control signal terminal CTRL outputs a second-level signal, Q3 is turned on, and DC_GND and POE_GND are connected, realizing dynamic switching of the ground line.

[0045] This control method allows for automatic ground wire switching between DC and PoE power supplies without the need for external mechanical operation, thus ensuring a smooth and continuous power switching process.

[0046] This embodiment achieves ground isolation and dynamic switching by setting a switching element 21 in the isolation switching module 200, which controls the connection between the first power supply negative voltage terminal DC_GND and the second power supply negative voltage terminal POE_GND under a control signal. This structure can prevent ground return current between the DC ground terminal and the POE ground terminal, reduce ground loop interference, and ensure stable and reliable power supply switching of the system.

[0047] In one implementation, Q3 can be an N-channel MOSFET or a P-channel MOSFET. When Q3 is an N-channel MOSFET, the second level signal is high, Q3 is turned on, connecting DC_GND and POE_GND; the first level signal is low, Q3 is turned off, disconnecting them. When Q3 is a P-channel MOSFET, the control signal logic is reversed: when the control signal terminal CTRL outputs a low level signal, Q3 is turned on; when the control signal terminal CTRL outputs a high level signal, Q3 is turned off.

[0048] In one implementation, the control signal terminal CTRL can be controlled by the status signal output of the POE power supply circuit 500. For example, after the POE power supply circuit completes power supply negotiation, its internal PD control circuit outputs a valid signal (such as the POE_GOOD signal), which provides the input level for the control signal terminal CTRL, thereby driving Q3 to conduct and connecting DC_GND and POE_GND.

[0049] When the POE power supply circuit 500 is de-energized or the PD control circuit outputs a failure signal, the CTRL level of the control signal terminal returns to the default level, and Q3 is turned off, realizing the automatic switch from POE power supply mode back to DC power supply mode.

[0050] Through the aforementioned control relationship, the isolation switching module 200 can automatically adjust the ground connection status according to the PoE power supply status, ensuring ground isolation during the power-on handshake of the PoE terminal, and ground connection after the power supply negotiation is completed. This solution can achieve seamless switching between PoE and DC power supply modes, maintaining continuous power supply to the load device 300.

[0051] In this way, by linking the control signal with the 500 state of the PoE power supply circuit, the power supply state can be automatically determined and switched. During the PoE protocol handshake and power supply negotiation, the ground wire is isolated to prevent accidental power supply or voltage backflow, and to ensure continuous and stable power supply to the system.

[0052] In this embodiment, the switching element 21 can be a MOSFET Q3, or it can be a thyristor or a relay. When using a MOSFET Q3, its low on-resistance and fast response speed enable microsecond-level ground switching, making it suitable for high-speed communication and video surveillance equipment. When using a thyristor, it maintains strong surge protection in high-voltage, high-current applications; when using a relay, it provides electrical isolation and reliable conduction in low-frequency control systems.

[0053] Therefore, this embodiment allows for flexible implementation of the isolation switching module 200 in different scenarios by selecting replaceable switching element types. The circuit design can be optimized according to the power supply voltage, load current and equipment response requirements, thereby improving system compatibility and adaptability.

[0054] like Figure 2 As shown, the isolation switching module 200 also includes a third diode D17. The positive terminal of the third diode D17 is coupled to the second node N2, and the negative terminal is coupled to the third node N3. The second node N2 is located between the second negative power supply terminal POE_GND and the second signal terminal S, and the third node N3 is located between the control terminal G and the control signal terminal CTRL.

[0055] During the power-on process of the POE power supply circuit 500, the third diode D17 forms a controlled conduction path between the control terminal G and the second signal terminal S, so that the potential of the control terminal G can gradually establish a stable potential with the control signal output by the POE power supply circuit 500, thereby preventing the control terminal from being falsely triggered or drifting during the POE power-on handshake and ensuring a smooth transition of ground switching.

[0056] In this way, by setting the third diode D17, potential buffering can be achieved during the POE power-on and protocol negotiation phases, preventing malfunctions caused by sudden signal changes at the control terminal G, improving the anti-interference capability and stability of the isolation switching module 200, and further ensuring the seamlessness of power supply switching.

[0057] Optionally, the third diode D17 can be a unidirectional TVS diode (Transient Voltage Suppression Diode) to clamp the control terminal G under transient overvoltage conditions.

[0058] Of course, the type of the third diode D17 is not limited to a unidirectional TVS diode. Other diode devices with potential buffering and clamping functions, such as Zener diodes or Schottky diodes, can also be used.

[0059] In this disclosure, such as Figure 2 As shown, the isolation switching module 200 also includes an RC soft-start circuit 22. The RC soft-start circuit 22 includes a resistor R16 and a capacitor C15 connected in series and coupled between the control terminal G and the first signal terminal D.

[0060] During the initial stage of POE or DC power-on, the RC soft-start circuit 22 uses the charging and discharging characteristics of capacitor C15 to delay the rise or fall of the control signal, thereby making the turn-on or turn-off process of MOSFET Q3 smoother and avoiding voltage surges or current surges during ground switching.

[0061] In this way, the delay characteristics of the RC soft-start circuit 22 can effectively reduce the rate of change of ground potential during power switching, suppress surge current, and prevent the current surge caused by the charging of the energy storage capacitor inside the DC power supply circuit 400 or the POE power supply circuit 500, thereby further improving the electrical safety and power supply stability of the system.

[0062] Figure 3 This disclosure presents an architectural diagram of a load power supply device according to an embodiment of the present disclosure, such as... Figure 3 As shown, the load power supply device may include a DC power supply circuit 400, a POE power supply circuit 500, and a power supply control circuit as described in any of the foregoing embodiments.

[0063] The output of the DC power supply circuit 400 is electrically connected to the first power supply input IN1 of the power supply control circuit, and the output of the POE power supply circuit 500 is electrically connected to the second power supply input IN2 of the power supply control circuit.

[0064] The power supply control circuit can automatically switch the power path according to the working status and level signal of the two power supplies, thereby ensuring that the load device 300 can be stably powered by DC power when the POE power supply is interrupted or the power supply handshake is not established. When the POE power supply circuit 500 completes the power supply negotiation and outputs a valid level signal, the isolation switching module 200 automatically turns on, connecting the first power supply negative voltage terminal DC_GND with the second power supply negative voltage terminal POE_GND, thereby realizing seamless power supply switching of the load device.

[0065] Through the above design, the problem of brief power outages in traditional redundant power supply designs is avoided during the power switching process between POE and DC, and the power supply reliability is significantly improved.

[0066] Figure 4 exhibit Figure 3The circuit topology diagram of the DC power supply circuit 400 shown is as follows: Figure 4 As shown, the DC power supply circuit 400 includes a DC soft-start circuit 41, which is configured to be coupled to the first power supply input terminal IN1 (e.g., ...). Figure 3 As shown), the DC soft-start circuit 41 is used to limit transient current in the initial stage of DC power supply DC_IN power-on, to prevent voltage fluctuations or surge current caused by capacitor charging or sudden load increase, thereby ensuring stable output of DC power supply.

[0067] The DC soft-start circuit 41 consists of a power MOSFET Q1 and an RC control network between its gate G and source S, used to achieve a smooth rise in output current during the DC power-up phase. The source S of Q1 is connected to the node between F1 and the subsequent circuit, the drain D is connected to the output terminal VCC_DC of the DC power supply circuit, and the gate G is connected to DC_GND through resistors R2 and R5.

[0068] In this configuration, the source (S) of MOSFET Q1 is coupled to F1. The gate (G) is controlled by an RC network with capacitors C1-C3 and resistor R1 connected in parallel at the node between F1 and the source (S) and the positive terminal of diode D3. This network delays the establishment of the gate voltage, thus slowly turning on Q1. The negative terminal of D3 is connected to the gate (G) of Q1 through resistor R2, forming a unidirectional conduction path to ensure the gate control voltage is steadily established during power-up, preventing false triggering or drift.

[0069] Through the above structural design, when the DC power supply circuit 400 is powered on, the RC control network causes Q1 to turn on slowly, achieving a smooth rise in output current and avoiding transient impacts. D3 and R2 ensure the stability of the gate voltage during the power-on phase, preventing control terminal drift or malfunction. This DC soft-start circuit, together with the input current limiting of F1, surge absorption of D2, and the downstream filter capacitor, can effectively ensure a smooth connection of the DC terminal to the subsequent power supply circuit, improving the reliability of the system power supply.

[0070] like Figure 4 As shown, the DC power supply circuit 400 also includes a first surge protection unit 42, which includes a self-resetting fuse F1 connected in series at the input terminal to limit the inrush current and protect the downstream circuit when the power-on period is initially started or when the input current increases abnormally. F1 is a positive temperature coefficient (PTC) thermistor.

[0071] The first surge protection unit 42 also includes a surge suppression diode D2. D2 adopts a dual TVS (Transient Voltage Suppressor) structure, with the positive terminals of the two TVS diodes connected opposite each other, and their negative terminals connected to the node between F1 and Q1 and DC_GND respectively, forming a symmetrical clamping path.

[0072] This structure can simultaneously absorb transient high voltage spikes in both the forward and reverse directions at the input terminal. When a surge voltage or polarity change occurs at the DC input terminal, D2 releases energy through bidirectional conduction, preventing overvoltage from damaging the MOSFET Q1 and subsequent circuit components, thereby improving the overall circuit's surge protection capability and stability.

[0073] In addition, the other components in the DC power supply circuit 400 are all conventional designs in the field and will not be described in detail here.

[0074] In this disclosure, Figure 5 The circuit topology diagram of the PoE power supply circuit 500 is shown below. Figure 5 As shown, the PoE power supply circuit 500 includes a bridge rectifier circuit 51. The input terminal POE_POW_P of the bridge rectifier circuit 51 is coupled to the Ethernet power supply pairs POE_VA1, POE_VB1, POE_VA2, and POE_VB2. This bridge rectifier circuit 51 can achieve polarity self-adaptation of the differential pairs, ensuring that the output terminal provides a DC voltage of the correct polarity regardless of the Ethernet cable connection direction, thus providing a stable input for the subsequent PD control circuit.

[0075] The bridge rectifier circuit 51 includes eight diodes D4, D5, D6, D7, D11, D12, D13, and D14, which are used to eliminate the uncertainty of the PSE power supply polarity and ensure that the output DC voltage direction is consistent.

[0076] In one embodiment, the POE power supply circuit 500 further includes a second surge protection unit 52.

[0077] In the second surge protection unit 52, dual TVS diodes D9 are connected in parallel between POE_POW_P and POE_GND, and dual TVS diodes D8 and D10 connected in series are also connected in parallel between POE_POW_P and POE_GND. This is used to absorb high-amplitude transient voltage pulses and prevent input voltage spikes from damaging subsequent circuits.

[0078] The filter capacitor C13 is used to smooth the DC output and suppress high-frequency noise to ensure the stable operation of the subsequent power processing circuit.

[0079] In alternative embodiments, such as Figure 3 and Figure 5 As shown, the POE power supply circuit 500 also includes a PD control circuit 53.

[0080] The PD control circuit 53 is connected to the control terminal of the isolation switching module 200 of the power supply control circuit via a signal line. After the PoE power supply circuit 500 completes the standard handshake and power supply negotiation, the PD control circuit 53 can output a first-level signal or a second-level signal to the isolation switching module 200 to indicate the current PoE power supply status.

[0081] When the PD control circuit 53 outputs a first-level signal, it indicates that the POE power supply has not been established or has been disconnected. The isolation switching module 200 remains disconnected, and the load is supplied by the DC power supply circuit 400 (e.g., Figure 3 Power supply (as shown); When the PD control circuit 53 outputs the second level signal, it indicates that the POE power supply has completed the handshake and can provide stable power. The isolation switching module 200 responds to the second level signal and turns on, making DC_GND and POE_GND electrically connected, realizing the common ground switching of the two power supplies.

[0082] Through the above signal control relationship, the automatic power supply switching logic based on PD handshake state is realized, without the need for additional control MCU or software logic, and the circuit structure is simplified and highly reliable.

[0083] Among them, the PD control circuit PD control chip U1 outputs the POE_GOOD signal through resistor R10 at its PG terminal. This signal is connected to the isolation switching module 200 to determine the POE power supply status and start the power supply switching.

[0084] Furthermore, this structure can simultaneously absorb transient high-voltage spikes in both the forward and reverse directions at the input. When a surge voltage or polarity change occurs at the POE input, the dual TVS diodes release energy through bidirectional conduction, preventing overvoltage breakdown of the subsequent MOSFETs and related circuit components, thereby improving the overall circuit's surge protection and stability.

[0085] Other components in the PoE power supply circuit are standard design content in this field and will not be described in detail here.

[0086] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the utility models disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A power supply control circuit, characterized in that, include: The first power supply branch, the second power supply branch, and the isolation switching module; The first power supply branch has a first power supply input terminal and a first power supply output terminal. The first power supply input terminal is configured to be coupled to a DC power supply circuit, and the first power supply output terminal is coupled to a first negative power supply terminal through a first capacitor and is configured to be coupled to a load device. The second power supply branch has a second power supply input terminal and a second power supply output terminal. The second power supply input terminal is coupled to the second power supply negative voltage terminal through the second capacitor and is configured to be coupled to the POE power supply circuit. The second power supply output terminal is coupled to the first power supply negative voltage terminal through the first capacitor and is configured to be coupled to the load device. The isolation switching module is coupled between the first negative power supply terminal and the second negative power supply terminal, and is configured as follows: The first level signal controls the cutoff, disconnecting the first and second negative voltage terminals of the power supply. The POE power supply circuit charges the second capacitor, and the DC power supply circuit supplies power through the first power supply branch. It is turned on by the second level signal, and connects the first power supply negative voltage terminal and the second power supply negative voltage terminal. The POE power supply circuit is powered through the second power supply branch. When the POE power supply circuit is powered off, triggering the second level signal to change to the first level signal, the circuit is switched to power supply through the first power supply branch.

2. The power supply control circuit according to claim 1, characterized in that, The first power supply branch includes a first diode, the positive terminal of which is coupled to the first power supply input terminal and the negative terminal is connected to the first power supply output terminal; The second power supply branch includes a second diode, the positive terminal of which is coupled to a first node between the second power supply input terminal and the second capacitor, and the negative terminal is coupled to the second power supply output terminal.

3. The power supply control circuit according to claim 1, characterized in that, The isolation switching module includes: a switching element, which is connected to a control signal terminal via a control terminal, coupled to the first negative voltage supply terminal via a first signal terminal, and coupled to the second negative voltage supply terminal via a second signal terminal.

4. The power supply control circuit according to claim 3, characterized in that, The switching element is a MOSFET, a thyristor, or a relay.

5. The power supply control circuit according to claim 3, characterized in that, The isolation switching module also includes: The third diode has its positive terminal connected to the second node and its negative terminal connected to the third node. The second node is located between the second negative voltage supply terminal and the second signal terminal, and the third node is located between the control terminal and the control signal terminal.

6. The power supply control circuit according to claim 3, characterized in that, The isolation switching module also includes: An RC soft-start circuit is coupled between the control terminal and the first signal terminal.

7. A load power supply device, characterized in that, include: DC power supply circuit; PoE power supply circuit; The power supply control circuit according to any one of claims 1-6; The output terminal of the DC power supply circuit is coupled to the first power supply input terminal, and the output terminal of the POE power supply circuit is coupled to the second power supply input terminal.

8. The load power supply device according to claim 7, characterized in that, The DC power supply circuit includes a DC soft-start circuit, which is configured to be coupled to the first power supply input terminal via the DC soft-start circuit.

9. The load power supply device according to claim 7, characterized in that, The PoE power supply circuit includes a PD control circuit, which is connected to the control terminal of the isolation switching module and is used to input the first level signal and the second level signal to the isolation switching module.

10. The load power supply device according to claim 7, characterized in that, Surge protection units are respectively provided at the front end of the first power input terminal and the second power input terminal.

Images