Power supply control method and USB power supply system

Abstract

The application discloses a power supply control method and a USB power supply system. When a second device is detected to be ready to be unplugged from a first device, the power supply control method sends a power-off preparation instruction to the second device, and when it is determined that the voltage on a VBUS power supply bus is less than or equal to a preset safety threshold, a switching element on the VBUS power supply bus is turned off.

Description

Technical Field

[0001] This application relates to the field of USB interface hot-plug protection technology, specifically to a power supply control method and a USB power supply system. Background Technology

[0002] In a USB Type-C hot-plug control scheme, the first device typically shuts off the switch on the VBUS path immediately upon detecting a disconnect signal.

[0003] However, since the second device cannot sense this impending physical disconnection event, its VBUS output voltage remains at a high voltage level at the moment of contact separation, causing severe arcing between the contacts under high voltage differential. Long-term accumulation can lead to interface erosion, black spots, and even fire hazards. Furthermore, the single-ended control mode cannot eliminate the time difference blind spot caused by the asynchronous response between the second and first devices. Summary of the Invention

[0004] This application provides a power supply control method and a USB power supply system to alleviate the aforementioned technical problems.

[0005] In a first aspect, this application provides a power supply control method applied to a first device. The power supply control method includes: sending a power-off preparation command to the second device in response to detecting a pull-out signal indicating that the second device is ready to be unplugged from the first device; and turning off the switching elements on the VBUS power bus when it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

[0006] Secondly, this application also provides a power supply control method applied to a second device. The power supply control method includes: in response to receiving a power-off preparation command sent by a first device, reducing the voltage on the VBUS power bus, wherein the power-off preparation command is issued by the first device in response to detecting that the second device is ready to be unplugged; and when the voltage on the VBUS power bus is less than or equal to a preset safety threshold, sending an acknowledgment signal to the first device, wherein the acknowledgment signal is used to instruct the first device to turn off the switching elements on the VBUS power bus.

[0007] Thirdly, this application also provides a power supply control method applied to a USB power supply system. The power supply control method includes: when a first device detects a disconnect signal indicating that a second device is ready to be disconnected, sending a power-off preparation command to the second device; when the power-off preparation command is received, the second device reduces the voltage on the VBUS power bus; when the voltage on the VBUS power bus is less than or equal to a preset safety threshold, the second device sends an acknowledgment signal to the first device; when the acknowledgment signal is received from the second device and / or the voltage on the VBUS power bus is detected to be less than or equal to the preset safety threshold, the second device turns off the switching elements on the VBUS power bus.

[0008] Fourthly, this application also provides a USB power supply system, which includes a first device, the first device including a switching element for controlling the on / off state of the VBUS power bus, the first device being configured to: send a power-off preparation command to the second device in response to detecting a disconnection signal of the second device being ready to be disconnected; and turn off the switching element when it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

[0009] Fifthly, this application also provides a USB power supply system, which includes a second device. The second device is configured to: reduce the voltage on the VBUS power bus in response to receiving a power-off preparation command sent by a first device, wherein the power-off preparation command is issued by the first device in response to detecting that the second device is ready to be unplugged; and send an acknowledgment signal to the first device when the voltage on the VBUS power bus is less than or equal to a preset safety threshold, wherein the acknowledgment signal is used to instruct the first device to turn off the switching elements on the VBUS power bus.

[0010] Sixthly, this application also provides a USB power supply system, which includes a first device and a second device. The first device includes a switching element on / off for controlling the VBUS power bus. The first device is configured to send a power-off preparation command to the second device when a disconnection signal is detected. The second device is configured to reduce the voltage on the VBUS power bus when it receives the power-off preparation command. When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, the first device sends an acknowledgment signal to the first device. The first device is further configured to turn off the switching element on the VBUS power bus when it receives the acknowledgment signal from the second device and / or detects that the voltage on the VBUS power bus is less than or equal to the preset safety threshold. Attached Figure Description

[0011] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0012] Figure 1 This is a schematic block diagram of a USB power supply system provided in an embodiment of this application.

[0013] Figure 2 This is a schematic diagram of a first power supply control method provided in an embodiment of this application.

[0014] Figure 3 This is a second flowchart illustrating the power supply control method provided in an embodiment of this application.

[0015] Figure 4 This is a schematic diagram of a third power supply control method provided in an embodiment of this application.

[0016] Figure 5 This is a schematic diagram of the fourth power supply control method provided in the embodiments of this application.

[0017] Figure label: 100. First device; 110. Switching element; 120. Female connector; 130. Detection and control module; 131. Detection circuit; 132. Control chip; 140. Drive module; 150. First controller; 160. Output capacitor; 170. Back-end load system; 200. Second device; 210. Voltage conversion circuit; 220. Male connector; 230. PD controller; 240. Second controller; 300. USB power supply system. Detailed Implementation

[0018] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more unless otherwise explicitly specified.

[0020] The USB Type-C interface has been widely used due to its reversible insertion convenience and high power transmission capabilities. However, during hot-swapping (especially hot-plugging), the VBUS power pins often still carry a high load current at the moment the contacts separate. Due to the air gap breakdown effect between the contacts, high-temperature arcs can easily be generated, leading to the burning of the gold plating layer of the interface, increased contact resistance, and consequently, intermittent charging, blackening of the interface, and even fire hazards, seriously affecting user experience and device safety.

[0021] To address the above problems, existing technologies mainly employ the following two types of arc suppression schemes: One approach is a single-point shutdown scheme at the device end, which triggers the MOSFET on the VBUS path to turn off by monitoring changes in the CC pin voltage. However, there is an inherent response delay (typically on the order of tens to hundreds of microseconds) from the detection of a voltage drop at the CC pin to the complete shutdown of the MOSFET. Within this delay window, the physical contacts have begun to separate but are still conducting electricity, and arcing is still unavoidable.

[0022] The second approach is a one-way voltage reduction scheme at the source, which reduces the output voltage when an anomaly is detected. However, this scheme also faces the problem of delayed voltage reduction response, and the source cannot know the physical connection status and power-off preparation status of the device, making it difficult to match the timing of voltage reduction with the contact separation time.

[0023] In summary, the core flaw of existing technologies lies in the unidirectional and asynchronous nature of control actions. Whether it's device-side shutdown or source-side voltage reduction, there's a lack of a closed-loop interaction mechanism of "advance notification—status confirmation—coordinated execution." This time lag between the actions at both ends is the fundamental reason why the arc cannot be completely eliminated when the device is pulled out.

[0024] This application aims to solve the arcing problem caused by single-end control during hot-plugging of existing USB TYPE-C interfaces. It provides a pull-out arc suppression scheme based on two-end handshake, which is deeply compatible with the existing CC pin detection and VBUS power path architecture. It does not require changes to the hardware topology or the addition of physical pins. Cooperative control can be achieved simply by upgrading the firmware logic of the source and device ends and the USB PD protocol interaction strategy.

[0025] The core concept of this solution lies in breaking the limitations of traditional single-ended decision-making and constructing a closed-loop collaborative mechanism that first notifies, then reduces voltage, and finally shuts down. Specifically, when the device detects an intention to unplug, it does not immediately shut down the switching elements on the VBUS path. Instead, it sends a power-off preparation command to the source end through the PD communication link carried by the CC pin. In response to this command, the source end actively reduces the VBUS output voltage to below a safe threshold (e.g., 1V). Only after the device confirms that the VBUS voltage is in a safe state or receives a confirmation signal from the source end that the voltage reduction is complete, does it perform the MOSFET shutdown operation.

[0026] The above two-way handshake process ensures that the physical contacts are in a state of zero voltage or microcurrent at the moment of separation, thereby fundamentally eliminating the physical conditions for the generation of electric arc.

[0027] like Figure 1 As shown, this embodiment provides a USB power supply system 300, which includes a first device 100. The first device 100 includes a switching element 110 for controlling the on / off state of the VBUS power bus. The first device 100 is configured to: send a power-off preparation command to the second device 200 in response to detecting a disconnection signal of the second device 200; and turn off the switching element 110 when it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

[0028] It is understood that the USB power supply system 300 provided in this embodiment sends a power-off preparation command to the second device 200 before the first device 100 turns off the switching element 110, forcing the second device 200 to actively reduce the VBUS voltage. Then, the first device 100 turns off the switching element 110 only when it confirms that the VBUS voltage is less than or equal to a preset safety threshold. This ensures that the VBUS voltage difference between the first device 100 and the second device 200 is extremely small when the physical contacts are separated, eliminating the energy conditions for arc generation from the root, significantly improving the service life of the interface and power safety, and does not require any changes to the physical hardware architecture of the USB interface, but can be achieved only through firmware upgrades.

[0029] It should be noted that the first device 100 is the power receiving device (power receiving end / device end) in the USB power supply system 300. When the first device 100 is working, the first controller 150 monitors the voltage change of the CC pin of the TYPE-C female connector 120 in real time through the detection control module 130. After recognizing the signal that the second device 200 is about to be unplugged, it will not immediately turn off the switching element 110. Instead, it will send a power-off preparation command to the second device 200 through the CC communication link. Only after the ADC detects that the VBUS voltage is ≤ the preset safety threshold, or after receiving the voltage reduction confirmation signal from the second device 200, will the driver module 140 turn off the switching element 110 to ensure that the VBUS voltage difference is less than 1V when the physical contacts are separated, thus suppressing the hot-plugging arc from the root.

[0030] The second device 200 is the power supply side device (power supply end / source end) in the USB power supply system 300. When the second device 200 is working, the second controller 240 receives the power-off preparation command sent by the first device 100 through the CC pin of the TYPE-C male connector 220 via the PD controller 230. Then, it adjusts the voltage conversion circuit 210 to reduce the VBUS output voltage to a preset safety threshold below 1V. After the voltage reduction is completed, it sends an acknowledgment signal to the first device 100 through the PD controller 230. This cooperates with the first device 100 to achieve coordinated voltage reduction before unplugging, fills the time difference blind spot of single-end control, and eliminates the energy conditions for arc generation from the power supply side.

[0031] like Figure 1 As shown, this embodiment also provides a USB power supply system 300, which includes a second device 200. The second device 200 is configured to: reduce the voltage on the VBUS power bus in response to receiving a power-off preparation command sent by a first device 100, wherein the power-off preparation command is issued by the first device 100 in response to detecting that the second device 200 is ready to be unplugged; and send an acknowledgment signal to the first device 100 when the voltage on the VBUS power bus is less than or equal to a preset safety threshold, wherein the acknowledgment signal is used to instruct the first device 100 to turn off the switching element 110 on the VBUS power bus.

[0032] It is understood that the USB power supply system 300 provided in this embodiment effectively fills the time gap blind spot of the existing single-end control scheme by transforming the second device 200 from a traditional passive power-off to an active collaborative voltage reduction executor. After receiving the power-off preparation command from the first device 100, the second device 200 actively reduces the VBUS voltage below the safety threshold and sends a confirmation signal back to the first device 100. This mechanism not only ensures that the VBUS voltage reaches a safe state without electric arc before the physical contacts separate, but also constructs a closed-loop control logic of request, response, and confirmation, enabling the actions of the second device 200 and the first device 100 to achieve precise synchronization within a millisecond time window. This fundamentally eliminates the energy source of contact arcing, significantly improves interface lifespan and the safety of high-power hot-plugging, and is fully compatible with the existing USB PD protocol architecture without the need for hardware modifications.

[0033] like Figure 1 As shown, this embodiment also provides a USB power supply system 300, which includes a first device 100 and a second device 200. The first device 100 includes a switching element 110 for controlling the on / off state of the VBUS power bus. The first device 100 is configured to send a power-off preparation command to the second device 200 when it detects a signal indicating that the second device 200 is ready to be unplugged. The second device 200 is configured to reduce the voltage on the VBUS power bus upon receiving the power-off preparation command. When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, it sends an acknowledgment signal to the first device 100. The first device 100 is further configured to turn off the switching element 110 on the VBUS power bus when it receives the acknowledgment signal from the second device 200 and / or detects that the voltage on the VBUS power bus is less than or equal to the preset safety threshold.

[0034] It is understood that the USB power supply system 300 provided in this embodiment constructs a closed-loop collaborative mechanism spanning the entire link between the first device 100 and the second device 200, completely overcoming the time difference blind spot of single-end control. By introducing a bidirectional handshake sequence during the unplugging process—the first device 100 requesting, the second device 200 stepping down, the second device 200 confirming, and the first device 100 executing—it ensures that the VBUS voltage has dropped to a safe threshold before the physical contacts separate, so that the contact is in a zero-voltage or micro-current state at the moment of current interruption, thus eliminating the energy conditions for arc generation at the root. Compared with the defects of isolated actions and lack of synchronization at both ends, this solution achieves precise matching of actions at both ends within a millisecond-level time window, significantly improving the interface lifespan and hot-plug safety in high-power USB PD scenarios, and fully reuses the existing CC communication and VBUS hardware architecture, possessing extremely high compatibility and feasibility.

[0035] It should be noted that the power-off preparation command refers to the command sent by the first device 100 to the second device 200 through the USB PD protocol carried by the CC pin after detecting the unplug signal, which is used to request a reduction in the VBUS voltage.

[0036] The preset safety threshold refers to a pre-set upper limit value of the voltage used to determine whether the VBUS voltage is in a state without the risk of arcing. In a preferred embodiment of this application, the range of the preset safety threshold is exemplarily 0V~1V, such as 0V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, or 1V, to ensure that the voltage difference is minimal when the contacts separate, thus eliminating arcing energy.

[0037] The confirmation signal is a feedback signal sent by the second device 200 to the first device 100 through the CC pin after reducing the VBUS voltage to below a preset safety threshold. It is used to indicate that the second device 200 has completed the voltage reduction operation and allows the first device 100 to perform the shutdown action.

[0038] Switching element 110 refers to a semiconductor switching device disposed on the VBUS power bus path of the first device 100 for controlled switching on or off of power supply. Switching element 110 may be exemplarily a P-MOSFET (P-channel metal-oxide-semiconductor field-effect transistor) or a MOSFET control circuit.

[0039] The second device 200 is ready to unplug when the USB TYPE-C male connector 220 of the second device 200 and the USB TYPE-C female connector 120 of the first device 100 are physically beginning to separate but not yet completely separated.

[0040] VBUS power bus refers to the conductor path in the USB TYPE-C interface specifically used for transmitting power supply voltage.

[0041] In some embodiments, such as Figure 1 As shown, the first device 100 also includes a TYPE-C female connector 120, a detection and control module 130, a drive module 140, and a first controller 150. The detection and control module 130 is connected to the CC pin of the TYPE-C female connector 120 and the first controller 150. The TYPE-C female connector 120 is connected to the VBUS power bus. The drive module 140 is connected to the first controller 150 and the switching element 110.

[0042] When the first controller 150 detects a voltage change on the CC pin through the detection control module 130, it determines that a pull-out signal has been detected, sends a power-off preparation command to the second device 200 through the communication link, and detects the voltage on the VBUS power bus. When it receives an acknowledgment signal from the second device 200 and / or detects that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, it shuts off the switching element 110.

[0043] It should be noted that the TYPE-C female connector 120 is used to physically connect to the TYPE-C male connector 220 of the second device 200. The TYPE-C female connector 120 is equipped with a VBUS pin (connecting to the VBUS power bus), CC1 / CC2 pins (configuration channel pins), and a ground pin, and is the physical carrier for realizing power transmission and communication link establishment.

[0044] The detection and control module 130 refers to the functional module integrated within the first device 100, which is used to sense the connection status and voltage parameters.

[0045] The drive module 140 refers to the power drive circuit within the first device 100 that is controlled by the first controller 150. Its function is to convert the logic level signal output by the first controller 150 into a drive voltage sufficient to drive the switching element 110 (such as a P-MOSFET) to turn on and off, thereby ensuring the reliable operation of the switching element 110.

[0046] The first controller 150 refers to the core logic control unit of the first device 100, which integrates a USB PD protocol stack and is configured to: obtain the CC pin status through the detection control module 130, make a decision and issue a power-off preparation command, monitor the VBUS voltage or receive an acknowledgment signal, and finally output a shutdown signal to the driver module 140.

[0047] During normal system operation, the first controller 150 monitors the voltage status of the CC pin on the TYPE-C female connector 120 in real time through the detection control module 130. When a drop or jump in the voltage of the CC pin is detected (i.e., a voltage change that meets the characteristics of being unplugged), the first controller 150 determines that the second device 200 is ready to be unplugged, and then sends a power-off preparation command to the second device 200 through the communication link formed by the CC pin. At the same time, the first controller 150 continuously monitors the voltage on the VBUS power bus or receives the confirmation signal sent by the second device 200 through the PD protocol. When it is confirmed that the VBUS voltage has dropped below the preset safety threshold, or when a confirmation signal is received that the second device 200 has completed the voltage reduction, the first controller 150 outputs a high-level signal through the drive module 140 to turn off the switching element 110 on the VBUS path and complete the safe power-off.

[0048] In this embodiment, the close cooperation between the first controller 150 and the detection control module 130 quickly converts the physical state change of the CC pin into a digital logic signal, solving the response delay problem in the traditional solution. At the same time, the drive module 140 is used to achieve precise control of the switching element 110, ensuring that the main circuit is cut off only when the VBUS voltage is extremely low (micro-current state).

[0049] This integrated design of detection, communication, confirmation, and driving enables the first device 100 to form a closed-loop collaboration with the step-down action of the second device 200 within a millisecond-level time window before physical contact separation. This eliminates the voltage and current conditions required for contact arcing at the source, significantly improving the hot-plug safety and contact life of high-power USB PD interfaces.

[0050] In some embodiments, such as Figure 1 As shown, the TYPE-C female connector 120 is used to connect the first device 100. The detection control module 130 includes a control chip 132 and a detection circuit 131. The detection circuit 131 is used to detect the voltage on the CC pin. The control chip 132 is connected to the detection circuit 131 and the first controller 150.

[0051] It should be noted that the control chip 132 refers to the embedded processing unit or interface management chip in the detection control module 130. In this application, its main function is to receive the CC pin voltage data collected by the detection circuit 131, perform preliminary judgment and debouncing processing, and transmit the processed pull-out signal to the first controller 150, acting as a communication bridge between the detection circuit 131 and the first controller 150.

[0052] The detection circuit 131 refers to the analog front-end circuit in the detection control module 130. Its input is directly connected to the CC pin of the TYPE-C female connector 120, and its output is connected to the control chip 132. Its core function is to sample, level-convert, or compare the analog voltage on the CC pin in real time, and convert the electrical changes of the physical layer into digital or analog signals that can be recognized by the control chip 132.

[0053] During system operation, the detection circuit 131 monitors the voltage on the CC pin of the TYPE-C female connector 120 in real time. When a pull-out operation occurs, as the contact area between the plug and the socket decreases, the impedance of the voltage divider circuit of the CC pin changes, causing the detection circuit 131 to capture the characteristic drop or fluctuation of the CC voltage. The detection circuit 131 transmits this analog change to the control chip 132. After the control chip 132 confirms that the change matches the characteristics of the pull-out signal through a preset debouncing algorithm, it sends a high-confidence pull-out interruption or status signal to the first controller 150 through the internal interface, thereby triggering the subsequent power-off preparation command sending process.

[0054] This embodiment significantly improves the accuracy and anti-interference capability of unplugging event detection by decoupling the detection function into a two-level architecture of detection circuit 131 (analog sensing) and control chip 132 (digital processing). Detection circuit 131 focuses on high-sensitivity voltage capture, while control chip 132 focuses on logic confirmation and filtering. This division of labor not only speeds up the response from physical change to logic signal and effectively shortens the response delay, but also relieves the real-time sampling load of the first controller 150, allowing it to focus more on the processing of the PD protocol stack and system scheduling. This ensures that the dual-end collaborative buck mechanism is reliably triggered within a millisecond time window, eliminating the generation of electric arcs at the source.

[0055] In some embodiments, such as Figure 1 As shown, the first device 100 also includes an output capacitor 160 and a back-end load system 170, both of which are connected to the back end of the switching element 110.

[0056] It should be noted that the output capacitor 160 refers to the energy storage filter element connected to the VBUS power bus of the first device 100. It is located at the rear end (load side) of the switching element 110 and is used to maintain the stability of the rear voltage at the moment the switching element 110 is turned off and to absorb the ripple generated by the sudden change in load current.

[0057] The back-end load system 170 refers to the functional module in the first device 100 that actually consumes electrical energy. It is connected to the back end of the switching element 110 and is powered by the VBUS power bus. For example, it can be the core processing system and peripheral circuits of a mobile phone motherboard, a laptop motherboard, or other portable electronic devices.

[0058] When the first controller 150 of the first device 100 performs a shutdown action, the second device 200 has reduced the VBUS voltage to below a preset safety threshold through communication coordination. At the instant that the switching element 110 completely cuts off the VBUS input path, the output capacitor 160 releases its stored charge to maintain the power supply continuity of the back-end load system 170 for a very short time and to smooth out voltage fluctuations caused by the switching action or the voltage reduction of the second device 200.

[0059] The presence of output capacitor 160 ensures that the power supply voltage of the downstream load system 170 will not drop sharply or be interrupted at the moment the switching element 110 is turned off, avoiding system reset, data loss, or logic abnormalities caused by power interruption. Simultaneously, in conjunction with the front-end cooperative buck mechanism, it minimizes the energy of the VBUS bus during contact separation, further suppressing the possibility of arcing and improving the smoothness and reliability of the system power-off process.

[0060] As the core functional unit of the first device 100, the back-end load system 170 continuously draws current from the VBUS power bus when plugged in. After detecting the unplug signal and initiating the coordinated power-off process, under the management of the first controller 150, it can selectively enter a low-power or safe shutdown sequence; throughout the process, it always draws power through the VBUS bus until the switching element 110 is turned off and the VBUS voltage drops below the safe threshold.

[0061] This embodiment employs a two-end handshake coordination mechanism, ensuring that the backend load system 170 remains in a controlled and stable power supply environment until physical disconnection is complete. This completely avoids the risks of power rail spikes, surges, or instantaneous overloads caused by arcing in traditional single-end shutdown schemes. This not only protects the safety of precision chips in the backend load system 170 but also eliminates the risk of interface burn-out caused by high arc temperatures, significantly extending the overall lifespan of the equipment and improving hot-swapping safety.

[0062] In some embodiments, such as Figure 1 As shown, the second device 200 includes a voltage conversion circuit 210, a TYPE-C male connector 220, a PD controller 230, and a second controller 240. The input side of the voltage conversion circuit 210 is used to connect to mains power, and the output side of the voltage conversion circuit 210 is connected to the VBUS pin of the TYPE-C male connector 220. The control side of the voltage conversion circuit 210 is connected to the output side of the second controller 240. The PD controller 230 is connected to the input side of the second controller 240 and the CC pin of the TYPE-C male connector 220. The TYPE-C male connector 220 is used to connect to the first device 100. When a power-off preparation command is received, the second controller 240 controls the voltage conversion circuit 210 to reduce the voltage on the VBUS power bus. When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, it sends an acknowledgment signal to the first device 100.

[0063] It should be noted that voltage conversion circuit 210 refers to the controllable power conversion device within the second device 200 that converts input AC power into DC power. The input side of voltage conversion circuit 210 is connected to AC power or an adapter input, the output side is connected to the VBUS pin of TYPE-C male connector 220, and the control side is regulated by the second controller 240, configured to dynamically adjust the VBUS output voltage according to instructions.

[0064] The TYPE-C male connector 220 serves as a physical connector, and it is equipped with a VBUS power pin, a CC configuration channel pin, and a ground pin. It is used to insert into the TYPE-C female connector 120 of the first device 100 to establish a physical connection for power transmission and communication links.

[0065] PD controller 230 refers to the integrated circuit within the second device 200 that specifically handles the physical and data link layer functions of the USB Power Delivery protocol. PD controller 230 is connected to the CC pin of the TYPE-C male connector 220 to monitor communication signals, and is connected to the second controller 240, responsible for the BMC signal encoding and decoding of the CC pin and the relay of PD message transmission and reception.

[0066] The second controller 240 refers to the core logic decision unit of the second device 200. It receives the power-off preparation command from the first device 100 through the PD controller 230, parses the command and outputs PWM or I2C control signals to the voltage conversion circuit 210 to perform the step-down operation. After confirming that the VBUS voltage meets the standard, it sends a confirmation signal to the first device 100 through the PD controller 230.

[0067] During normal system operation, the voltage conversion circuit 210 converts the input AC power into a set DC voltage (e.g., 20V) and supplies power to the first device 100 through the TYPE-C male connector 220. When the PD controller 230 receives the power-off preparation command from the first device 100 through the CC pin, it transmits the power-off preparation command to the second controller 240. The second controller 240 parses the command and then outputs a step-down signal through the control side to drive the voltage conversion circuit 210 to quickly reduce the VBUS output voltage below the preset safety threshold. After that, the second controller 240 sends an acknowledgment signal (e.g., PS_RDY) to the first device 100 through the PD controller 230, instructing the first device 100 to perform a shutdown operation.

[0068] The architecture of the second device 200 separates protocol processing (PD controller 230) from policy decision-making (second controller 240), enabling rapid response and precise execution of power-off preparation commands. Under the direct control of the second controller 240, the voltage conversion circuit 210 can pull the high voltage VBUS down to a safe threshold within milliseconds, effectively eliminating the arc energy during contact separation. At the same time, the closed-loop feedback mechanism (acknowledgment signal) constructed by the PD controller 230 ensures millisecond-level synchronization between the voltage reduction action of the second device 200 and the shutdown action of the first device 100, completely solving the time difference blind spot of traditional single-end control and significantly improving the hot-plug safety and interface lifespan of high-power USB PD interfaces.

[0069] like Figure 2 As shown, this embodiment also provides a power supply control method applied to a first device 100. The power supply control method includes the following steps: Step S11: In response to detecting a pull-out signal that the second device is ready to be unplugged from the first device, a power-off preparation command is sent to the second device.

[0070] Step S12: When it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, turn off the switching elements on the VBUS power bus.

[0071] It is understood that the power supply control method provided in this embodiment sends a power-off preparation command to the second device before the first device shuts off the switching element, forcing the second device to actively reduce the VBUS voltage. Then, the first device shuts off the switching element only when it confirms that the VBUS voltage is less than or equal to a preset safety threshold. This ensures that the VBUS voltage difference between the first and second devices is extremely small when the physical contacts are separated, eliminating the energy conditions for arc generation from the root, significantly improving the service life of the interface and power safety. Moreover, it does not require any changes to the physical hardware architecture of the USB interface and can be achieved only through firmware upgrades.

[0072] like Figure 3 As shown, this embodiment also provides a power supply control method applied to a second device 200. The power supply control method includes the following steps: Step S21: In response to receiving a power-off preparation command sent by the first device, reduce the voltage on the VBUS power bus. The power-off preparation command is issued by the first device in response to detecting that the second device is ready to be unplugged.

[0073] Step S22: When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, an acknowledgment signal is sent to the first device. The acknowledgment signal is used to instruct the first device to turn off the switching elements on the VBUS power bus.

[0074] It is understandable that the power supply control method provided in this embodiment effectively fills the time lag blind spot of existing single-end control schemes by transforming the second device from a traditional passive power-off device to an active collaborative voltage reduction executor. After receiving the power-off preparation command from the first device, the second device actively reduces the VBUS voltage below the safety threshold and sends a confirmation signal back to the first device. This mechanism not only ensures that the VBUS voltage reaches a safe state without electric arc before the physical contacts separate, but also constructs a closed-loop control logic of request, response, and confirmation, enabling the actions of the second device and the first device to achieve precise synchronization within a millisecond time window. This fundamentally eliminates the energy source of contact arcing, significantly improves interface lifespan and the safety of high-power hot-plugging, and is fully compatible with the existing USB PD protocol architecture without requiring hardware modifications.

[0075] like Figure 4 As shown, this embodiment also provides a power supply control method applied to a USB power supply system 300. The power supply control method includes the following steps: Step S31: When the first device detects the unplug signal of the second device preparing to unplug, it sends a power-off preparation command to the second device.

[0076] Step S32: When a power-off preparation command is received, the second device reduces the voltage on the VBUS power bus.

[0077] Step S33: When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, the second device sends an acknowledgment signal to the first device.

[0078] Step S34: When an acknowledgment signal is received from the second device and / or the voltage on the VBUS power bus is detected to be less than or equal to a preset safety threshold, the first device turns off the switching element on the VBUS power bus.

[0079] It is understandable that the power supply control method provided in this embodiment constructs a closed-loop collaborative mechanism spanning the entire link between the first and second devices, completely overcoming the time difference blind spot of single-end control. By introducing a bidirectional handshake sequence of first device request, second device voltage reduction, second device confirmation, and first device execution during the unplugging process, it ensures that the VBUS voltage has dropped to a safe threshold before the physical contacts separate, so that the contact is in a zero voltage or micro-current state at the moment of current interruption, eliminating the energy conditions for arc generation from the root. Compared with the defects of isolated actions and lack of synchronization at both ends, this solution achieves precise matching of actions at both ends within a millisecond-level time window, significantly improving the interface life and hot-plug safety in high-power USB PD scenarios, and fully reuses the existing CC communication and VBUS hardware architecture, possessing extremely high compatibility and feasibility.

[0080] In some embodiments, such as Figure 5 As shown, in response to detecting a signal indicating that the second device is preparing to be unplugged from the first device, a power-off preparation command is sent to the second device, including the following steps: Step S41: Detect the voltage of the CC pin of the first device.

[0081] Step S42: When the voltage of the CC pin of the first device changes, it is determined that a pull-out signal has been detected.

[0082] It should be noted that detecting the voltage of the CC pin of the first device refers to the operation of real-time sampling and monitoring of the analog voltage of the CC pin on the TYPE-C female connector through the detection circuit in the detection control module of the first device. In this application, the voltage of the CC pin is a stable level generated by a voltage divider circuit composed of the pull-up resistor / current source of the second device and the pull-down resistor (5.1kΩ) of the first device.

[0083] The voltage change of the CC pin of the first device refers to the electrical phenomenon that, during the physical removal process, due to the reduction of the contact area of ​​the contact point, the voltage divider circuit impedance of the CC pin no longer maintains a precise 5.1kΩ, thereby causing the CC pin voltage to deviate from the normal operating range (0.4V~2.2V) and drift towards the open circuit level (~3.3V).

[0084] During normal system operation, the detection circuit of the first device monitors the voltage of the CC pin in real time. This voltage is stabilized in a specific operating range (such as 0.41V, 0.92V, or 1.68V) by a voltage divider circuit formed by the pull-up resistor of the second device and the pull-down resistor of the first device. When a pull-out operation occurs, as the contacts of the TYPE-C male and female connectors physically separate, the contact impedance increases sharply, disrupting the original voltage divider balance, causing the CC pin voltage to drop or rise characteristically. After the detection circuit captures this change in analog quantity, it transmits it to the control chip. The control chip (after filtering out mechanical jitter interference through a preset debouncing algorithm) confirms that the voltage change conforms to the electrical characteristics of "the second device is ready to be pulled out", thereby generating a pull-out signal and sending it to the first controller, thus triggering the subsequent power-off preparation command sending process.

[0085] This embodiment significantly improves the sensitivity and anti-interference capability of unplugging event detection by decoupling voltage sampling and logic judgment into a two-level architecture where the detection circuit and control chip work together. The detection circuit focuses on high-precision analog signal capture, while the control chip focuses on digital domain debouncing and status confirmation. This division of labor not only quickly converts physical layer changes into reliable logic signals, effectively shortening the delay from contact loosening to system response, but also relieves the real-time sampling load of the first controller, allowing it to focus more on PD protocol stack processing. This mechanism ensures reliable triggering of the dual-end collaborative bucking process within a millisecond time window, gaining valuable prediction time for completely eliminating arcing, and is a key front-end link in solving the blind spot of single-end control time difference.

[0086] In some embodiments, when it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, turning off the switching elements on the VBUS power bus includes: When an acknowledgment signal is received from the second device and / or the voltage on the VBUS power bus is detected to be less than or equal to a preset safety threshold, the switching element on the VBUS power bus is turned off. The acknowledgment signal is used to indicate that the second device has reduced the voltage on the VBUS power bus to below the preset safety threshold.

[0087] It should be noted that at the end of the coordinated power-off process, the first controller of the first device is in a waiting execution state: it monitors the shutdown conditions through two parallel paths: one is to listen to the CC line through the PD controller to determine whether it has received the acknowledgment signal (PS_RDY) sent by the second device; the other is to continuously monitor the actual voltage on the VBUS power bus through the ADC sampling circuit. When the first controller receives the acknowledgment signal and / or detects that the VBUS voltage is less than or equal to 1V, it determines that the physical contacts are in a safe micro-current or zero-voltage state, and then outputs a high-level signal through the drive module to turn off the switching elements on the VBUS path and completely cut off the power supply circuit.

[0088] This embodiment can construct a dual-condition redundancy triggering mechanism of communication confirmation and local detection, which greatly improves the reliability and security of system shutdown: on the one hand, the confirmation signal of the second device ensures the protocol-level synchronization of the actions of both ends; on the other hand, local voltage detection provides hardware-level fallback protection, so that even if the communication link is abnormal, it can be safely shut down based on the measured voltage.

[0089] This dual-insurance mechanism completely eliminates the blind spot of single-end control in response delay, ensuring that the VBUS voltage difference is suppressed to a level that cannot generate an electric arc at the last moment before the physical contacts are completely separated. This fundamentally solves the interface burn-out and safety hazards, and can be achieved without changing the existing hardware architecture, only through firmware logic optimization.

[0090] In some embodiments, the power outage preparation instruction includes at least one of a vendor-defined message, a hard reset message, and a power role swap message.

[0091] It should be noted that Vendor Defined Messages (VDMs) refer to non-standardized proprietary commands based on the USB PD protocol extension. Specifically, they refer to messages constructed by the first controller of the first device, carrying a specific Vendor Identifier (VID) and a "reduce voltage to a preset safety threshold" command payload, sent to the second device via the CC pin. This is used to achieve private handshake collaboration between the two devices without interfering with standard power supply negotiation. An example of a Vendor Defined Message could be "Preparing to unplug, please reduce output voltage".

[0092] A Hard Reset message refers to a mandatory reset control message defined by the USB PD protocol. It is reused as a degradation trigger mechanism: when the first device sends this message, it forces the second device to pull the VBUS voltage below the specified threshold of 0V~0.8V, and uses the voltage drop generated by this standard action to achieve arc suppression, without relying on the second device's ability to resolve proprietary VDM.

[0093] The Power Role Swap message (PR_Swap) refers to the standardized data message in the USB PD protocol used to negotiate the switching of power supply direction. As an alternative standard protocol borrowing scheme, the first device initiates this message to trigger the VBUS reconfiguration process of the second device. By taking advantage of the power loss and rebuild gap that VBUS inevitably experiences during the role switching process, the voltage at which the contacts separate can be reduced.

[0094] Upon detecting the unplug signal, the first controller prioritizes the vendor-defined message (VDM) as the power-off preparation instruction: it fills the message with its own VID and the target step-down value (such as 1V) and sends it to the second device via the CC pin; if the second device's PD controller recognizes the VID and parses it successfully, it immediately performs the step-down.

[0095] If no response is received within the timeout period (indicating that the second device does not support the private command), the first controller triggers a Hard Reset message, forcing the second device to perform a VBUS hardware reset at the protocol level.

[0096] In extreme compatibility scenarios, a power role swap message (PR_Swap) can also be sent to assist in voltage reduction by utilizing the forced power-down phase of VBUS in the standard role switching process. This ensures that regardless of whether the second device supports the proprietary protocol, the PD specification features can be used to gain a time window for low-voltage disconnection.

[0097] This solution perfectly balances the precision of collaborative control with the robustness of system compatibility by constructing a three-tiered instruction system with proprietary instructions as the primary approach and standard instructions as a fallback. The application of VDM instructions enables devices within the same brand ecosystem to achieve millisecond-level precise voltage reduction and seamless switching, completely eliminating arcing. Meanwhile, the reuse strategy of Hard Reset and PR_Swap provides an effective degradation protection path for non-standard accessories or non-smart chargers, ensuring that the VBUS contacts are at the lowest possible voltage state the moment of disconnection in any connection scenario.

[0098] This design maximizes the coverage of second devices of different grades and protocols without changing the USB Type-C hardware architecture, solving the pain point of insufficient compatibility of a single solution.

[0099] In summary, the power supply control method proposed in this application upgrades the traditional single-end shutdown to a closed-loop control process of first notifying, then stepping down the voltage, and finally shutting down by constructing a two-way handshake coordination mechanism between the second and first devices. The specific implementation process includes the following four stages: The first controller of the first device monitors the voltage change of the CC pin of the TYPE-C female connector in real time through the detection control module (including control chip and detection circuit). When the voltage of the CC pin deviates from the normal connection range (0.4V~2.2V) and meets the characteristics of being unplugged, the first controller determines that "the second device is ready to be unplugged". The existing detection logic is used in this stage, but the first controller does not immediately trigger the switching element to turn off, but activates the coordinated power-off process.

[0100] After determining the intention to unplug, the first controller immediately sends a power-off preparation command to the second device through the communication link formed by the CC pin. This command preferentially uses a vendor-defined message (VDM) carrying proprietary commands, requiring the second device to reduce the VBUS output voltage to below 1V within milliseconds. If the second device does not support VDM, it reuses the Hard Reset message or Power Role Swap message (PR_Swap) in the standard PD protocol as a degradation triggering method, using the characteristics of the standard protocol to force or indirectly achieve VBUS voltage reduction.

[0101] After receiving the power-off preparation command through the PD controller, the second controller of the second device immediately regulates the voltage conversion circuit to reduce the VBUS output voltage. When the VBUS voltage drops below a preset safety threshold (e.g., 1V), the second controller sends an acknowledgment signal (e.g., PS_RDY message or VDM ACK) to the first device through the PD controller, indicating that the voltage reduction operation is complete. If the second device cannot recognize the command, it automatically reverts to the existing single-ended shutdown scheme to ensure compatibility.

[0102] After sending a command, the first controller of the first device continuously monitors the VBUS voltage and the communication link. When the VBUS voltage is detected to be ≤1V via the ADC, and / or an acknowledgment signal is received from the second device, the first controller turns off the P-MOSFET switching element on the VBUS path via the drive module. At this time, the physical contacts are not completely separated, but the voltage difference between VBUS and GND is extremely small (<1V), and the residual current cannot form a high-temperature arc, fundamentally eliminating interface erosion and safety hazards.

[0103] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0104] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A power supply control method, characterized in that, Applied to the first device, the power supply control method includes: In response to detecting a pull-out signal that the second device is preparing to be pulled out of the first device, a power-off preparation command is sent to the second device; When it is determined that the voltage on the VBUS power bus is less than or equal to a safety threshold, the switching elements on the VBUS power bus are turned off.

2. The power supply control method according to claim 1, characterized in that, The step of sending a power-off preparation command to the second device in response to detecting a signal indicating that the second device is preparing to be unplugged from the first device includes: Detect the voltage at the CC pin of the first device; When the voltage of the CC pin of the first device changes, it is determined that the pull-out signal has been detected.

3. The power supply control method according to claim 1, characterized in that, The power outage preparation instruction includes at least one of a vendor-defined message, a hard reset message, and a power role swap message.

4. The power supply control method according to any one of claims 1-3, characterized in that, The step of turning off the switching elements of the VBUS power bus when it is determined that the voltage on the VBUS power bus is less than or equal to a preset safety threshold includes: When an acknowledgment signal is received from the second device and / or the voltage on the VBUS power bus is detected to be less than or equal to a preset safety threshold, the switching element on the VBUS power bus is turned off. The acknowledgment signal is used to indicate that the second device has reduced the voltage on the VBUS power bus to below the preset safety threshold.

5. A power supply control method, characterized in that, Applied to a second device, the power supply control method includes: In response to receiving a power-off preparation command sent by a first device, the voltage on the VBUS power bus is reduced, the power-off preparation command being sent by the first device in response to detecting that the second device is ready to be unplugged; When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, an acknowledgment signal is sent to the first device. The acknowledgment signal is used to instruct the first device to turn off the switching elements on the VBUS power bus.

6. The power supply control method according to claim 5, characterized in that, The power outage preparation instruction includes at least one of a vendor-defined message, a hard reset message, and a power role swap message.

7. A power supply control method, characterized in that, The power supply control method, applied to a USB power supply system, includes: When the first device detects the pull-out signal of the second device preparing to pull out, it sends a power-off preparation command to the second device. When the power-off preparation command is received, the second device reduces the voltage on the VBUS power bus; When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, the second device sends an acknowledgment signal to the first device. When the second device receives an acknowledgment signal from the second device and / or detects that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, the second device shuts off the switching elements on the VBUS power bus.

8. The power supply control method according to claim 7, characterized in that, When the first device detects a signal indicating that the second device is about to be unplugged, it sends a power-off preparation command to the second device, including: Detect the voltage at the CC pin of the first device; When the voltage of the CC pin of the first device changes, it is determined that the pull-out signal has been detected.

9. The power supply control method according to claim 7, characterized in that, The power outage preparation instruction includes at least one of a vendor-defined message, a hard reset message, and a power role swap message.

10. A USB power supply system, characterized in that, The USB power supply system includes a first device, the first device including a switching element for controlling the on / off state of the VBUS power bus, the first device being used for: In response to detecting a pull-out signal indicating that the second device is ready to be unplugged, a power-off preparation command is sent to the second device; When the voltage on the VBUS power bus is determined to be less than or equal to a preset safety threshold, the switching element is turned off.

11. The USB power supply system according to claim 10, characterized in that, The first device also includes a TYPE-C female connector, a detection and control module, a drive module, and a first controller. The detection and control module is connected to the CC pin of the TYPE-C female connector and the first controller. The TYPE-C female connector is connected to the VBUS power bus. The drive module is connected to the first controller and the switching element. When the first controller detects a voltage change in the CC pin through the detection control module, it determines that the pull-out signal has been detected, sends a power-off preparation command to the second device through the communication link, and detects the voltage on the VBUS power bus. When it receives an acknowledgment signal from the second device and / or detects that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, it shuts off the switching element.

12. The USB power supply system according to claim 11, characterized in that, The TYPE-C female connector is used to connect to the first device. The detection and control module includes a control chip and a detection circuit. The detection circuit is used to detect the voltage on the CC pin. The control chip is connected to the detection circuit and the first controller.

13. A USB power supply system, characterized in that, The USB power supply system includes a second device, the second device being used for: In response to receiving a power-off preparation command sent by a first device, the voltage on the VBUS power bus is reduced, the power-off preparation command being issued by the first device in response to detecting that the second device is ready to be unplugged; When the voltage on the VBUS power bus is less than or equal to a preset safety threshold, an acknowledgment signal is sent to the first device. The acknowledgment signal is used to instruct the first device to turn off the switching elements on the VBUS power bus.

14. The USB power supply system according to claim 13, characterized in that, The second device includes a voltage conversion circuit, a TYPE-C male connector, a PD controller, and a second controller. The input side of the voltage conversion circuit is used to connect to mains power. The output side of the voltage conversion circuit is connected to the VBUS pin of the TYPE-C male connector. The control side of the voltage conversion circuit is connected to the output side of the second controller. The PD controller is connected to the input side of the second controller and the CC pin of the TYPE-C male connector. The TYPE-C male connector is used to connect to the first device. The second controller is used to control the voltage conversion circuit to reduce the voltage on the VBUS power bus when it receives the power-off preparation command, and to send the confirmation signal to the first device when the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

15. A USB power supply system, characterized in that, The USB power supply system includes a first device and a second device, wherein the first device includes a switching element for controlling the on / off state of the VBUS power bus. The first device is used to send a power-off preparation command to the second device when it detects a signal that the second device is ready to be unplugged. The second device is used to reduce the voltage on the VBUS power bus when it receives the power-off preparation command; and to send an acknowledgment signal to the first device when the voltage on the VBUS power bus is less than or equal to a preset safety threshold. The first device is further configured to turn off the switching elements on the VBUS power bus when it receives the acknowledgment signal from the second device and / or detects that the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

16. The USB power supply system according to claim 15, characterized in that, The first device also includes a TYPE-C female connector, a detection and control module, a drive module, and a first controller. The detection and control module is connected to the CC pin of the TYPE-C female connector and the first controller. The TYPE-C female connector is connected to the VBUS power bus. The drive module is connected to the first controller and the switching element. When the first controller detects a voltage change in the CC pin through the detection control module, it determines that the pull-out signal has been detected, sends a power-off preparation command to the second device through the communication link, and detects the voltage on the VBUS power bus. When it receives an acknowledgment signal from the second device and / or detects that the voltage on the VBUS power bus is less than or equal to a preset safety threshold, it shuts off the switching element.

17. The USB power supply system according to claim 16, characterized in that, The TYPE-C female connector is used to connect to the first device. The detection and control module includes a control chip and a detection circuit. The detection circuit is used to detect the voltage on the CC pin. The control chip is connected to the detection circuit and the first controller.

18. The USB power supply system according to claim 15, characterized in that, The second device includes a voltage conversion circuit, a TYPE-C male connector, a PD controller, and a second controller. The input side of the voltage conversion circuit is used to connect to mains power. The output side of the voltage conversion circuit is connected to the VBUS pin of the TYPE-C male connector. The control side of the voltage conversion circuit is connected to the output side of the second controller. The PD controller is connected to the input side of the second controller and the CC pin of the TYPE-C male connector. The TYPE-C male connector is used to connect to the first device. The second controller is used to control the voltage conversion circuit to reduce the voltage on the VBUS power bus when it receives the power-off preparation command, and to send the confirmation signal to the first device when the voltage on the VBUS power bus is less than or equal to a preset safety threshold.

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