Power transmission system and method for detecting overcurrent and faults

Abstract

A power delivery system includes a power sourcing equipment, a powered equipment, and a transmission line. When the power sourcing equipment is electrically connected to the powered equipment through the transmission line, the power sourcing equipment can use a current detection circuit to determine whether the powered equipment has an overcurrent. Meanwhile, the power sourcing equipment can determine whether the current detection circuit is failed according to a specific pin of the power sourcing equipment, and thus provide a single fault protection when the current detection circuit is determined to be failed.

Description

Technical Field

[0001] This invention relates to a power transmission system and related methods, and more particularly to a power transmission system and related methods capable of detecting overcurrent and faults. Background Technology

[0002] Power supplies are used to provide the power required for the operation of electronic devices. To prevent electronic devices from exceeding the power supply's safe load range due to excessive load, prior art power supplies typically incorporate overcurrent detection and protection circuits. When the detected load current exceeds the load limit, an overcurrent protection signal is output to notify the power supply to take appropriate protective measures (such as shutdown) to prevent instantaneous high current from damaging internal components or the load. However, when the current detection circuit malfunctions, it cannot monitor the load current value to provide protection. Therefore, a method and system for detecting overcurrent and faults are needed. Summary of the Invention

[0003] This invention provides a power transmission system capable of detecting overcurrent and faults, comprising a receiving device, a transmission line, and a supplying device. The supplying device includes a first pin, a second pin, a third pin, a power conversion circuit, a switching element, a device connection detection and identification circuit, a voltage extraction circuit, a current detection circuit, a current and fault judgment circuit, and a control circuit. The power conversion circuit supplies power to the receiving device through the second pin. The switching element selectively turns on or off the power supply path between the power conversion circuit and the second pin based on a switching control signal. The device connection detection and identification circuit determines whether the supplying device is electrically connected to the receiving device through the transmission line and outputs a corresponding first signal. The voltage extraction circuit records the initial voltage value of the third pin during a first period when the supplying device is electrically connected to the receiving device but not supplying power, and measures the current voltage value of the third pin during a second period when the power conversion circuit supplies power to the receiving device through the second pin. The detection circuit monitors the load current during the second period. The current and fault determination circuit is used to determine whether the current voltage value exceeds the initial voltage value and thus exceeds the voltage threshold during the second period, and outputs a corresponding second signal; and to determine whether the load current value is less than the current threshold during the second period, and outputs a corresponding third signal. The control circuit is coupled to the device, connecting the detection and identification circuit and the current and fault determination circuit to receive the first signal, the second signal, and the third signal. When the second signal determines that the current voltage value exceeds the initial voltage value and thus exceeds the voltage threshold, and the third signal determines that the load current value is less than the current threshold, the control circuit turns off the switching element to cut off the power supply path between the power conversion circuit and the second pin.

[0004] The present invention also provides a method for detecting overcurrent and faults in a power transmission system, comprising: determining whether a power supply device in the power transmission system is electrically connected to a power receiving device in the power transmission system; during a first period when the power supply device is electrically connected to the power receiving device but not supplying power to the power receiving device, recording the initial voltage value of a first pin in the power supply device; during a second period when the power conversion circuit supplies power to the power receiving device through a second pin, measuring the current voltage value of the first pin and monitoring the value of the load current; and when it is determined that the value of the load current is less than a current threshold and the current voltage value is greater than the initial voltage value exceeding the voltage threshold, the power supply device performs single fault protection to stop supplying power to the power receiving device. Attached Figure Description

[0005] Figure 1 This is a functional block diagram of a power transmission system according to an embodiment of the present invention.

[0006] Figure 2A and Figure 2B This is a schematic diagram of the existing USB Type-C standard transmission interface.

[0007] Figure 3 This is a schematic diagram of an embodiment of the power transmission system in this invention.

[0008] Figure 4 This is a schematic diagram of an embodiment of the power transmission system in this invention.

[0009] Figure 5 This is a schematic diagram of an embodiment of the power transmission system in this invention.

[0010] Figure 6 This is a schematic diagram of an embodiment of the power transmission system in this invention.

[0011] Figure 7 This is a flowchart illustrating the operation of the power transmission system in an embodiment of the present invention. Detailed Implementation

[0012] Figure 1 This is a functional block diagram of a power delivery (PD) system 100 according to an embodiment of the present invention. The power delivery system 100 includes a power supply device 10, a power receiving device 20, and a transmission line 30. The power supply device 10 includes a power conversion circuit 110, a switching element 120, a device connection detection and identification circuit 130, a current detection circuit 140, a voltage extraction circuit 150, a current and fault judgment circuit 160, and a control circuit 170. The power supply device 10 can be electrically connected to the power receiving device 20 through the transmission line 30 and supplies the power required for the operation of the power receiving device 20.

[0013] In embodiments of the present invention, the transmission line 30 may employ a transmission interface conforming to the Universal Serial Bus (USB) Type-C specification. Figure 2A and Figure 2B This is a schematic diagram of the existing USB Type-C standard transmission interface, in which... Figure 2A The pinout diagram of the USB Type-C female connector is shown, and Figure 2B The pinout diagram of the USB Type-C male connector is shown. To support reversible insertion, both the USB Type-C female and male connectors have two sets of symmetrical pins, designated A1-A12 and B1-B12 respectively. The differential signal transmission pairs TX1+ / TX1- / RX1+ / RX1- and TX2+ / TX2- / RX2+ / RX2- are used for data transmission. VBUS is the pin used for bus power supply, while VCONN is the pin used for powering the cable controller (located only on the USB Type-C male connector). The configuration channel pins CC1 / CC2 are used to detect reversibility, detect connection status, determine the downstream facing port (DFP) and upstream facing port (UFP), configure the power supply pins VBUS and VCONN, configure other modes (alternateor accessory mode), and perform other related power transmission communication operations. The D+ / D- pins are used to backward support the USB 2.0 specification, the SBU1 / SBU2 pins are used to transmit auxiliary signals, and GND is the ground pin. The power supply will only provide power through its power supply pin VBUS when a connected device is detected based on the configuration channel pins CC1 / CC2.

[0014] Figures 3 to 6 This is a schematic diagram illustrating an embodiment of the power transmission system 100 of the present invention. In this invention, the power supply device 10 and the power receiving device 20 each include pins conforming to a specific transmission specification (e.g., USB Type-C), and the transmission line 30 includes a source end 31 and a sink end 32. Depending on the type of power supply device 10 and power receiving device 20, the source end 31 and the sink end 32 may each be a USB Type-C female connector as shown in FIG. 2A or... Figure 2B The USB Type-C male connector is shown in Figure 3. For simplicity, see Figure 3 to... Figure 6 Only the configuration channel pins CC1 / CC2, configuration channel transmission line CC, power supply pins and transmission line VBUS, and ground pins and transmission line GND are shown, where the internal impedance of transmission line 30 is determined by R. GND To express.

[0015] exist Figures 3 to 6 In the power delivery system 100 shown, the power conversion circuit 110 supplies power to the load via the power supply pin VBUS. The control circuit 170 outputs a switching control signal V based on signals S1-S3. G The switching element 120 is selectively turned on or off, thereby selectively connecting or disconnecting the power supply path between the power conversion circuit 110 and the power supply pin VBUS: when the switching element 120 is off, the power supply terminal device 10 is in an externally unpowered state; when the switching element 120 is on, the power supply terminal device 10 is in an externally powered state. In this embodiment of the invention, the switching element 120 may be a bipolar junction transistor (BJT), a field-effect transistor (FET), or other similar switching elements. However, the type of switching element 120 does not limit the scope of this invention.

[0016] exist Figures 3 to 6 In the power transmission system 100 shown, the device connection detection and identification circuit 130 includes pull-up resistors RP1 and RP2, and an identification circuit 35. The configuration channel pin CC1 of the power supply device 10 is coupled to a positive bias voltage V+ via pull-up resistor RP1, and the configuration channel pin CC2 of the power supply device 10 is coupled to a positive bias voltage V+ via pull-up resistor RP2. Furthermore, the configuration channel pin CC1 of the powered device 20 is coupled to ground potential GND via pull-down resistor RD1, and the configuration channel pin CC2 of the powered device 20 is coupled to ground potential GND via pull-down resistor RD2. The identification circuit 35 can output a signal S1 related to the connection status based on the configuration channel pins CC1 and CC2 of the power supply device 10. Figure 3 and Figure 4 In the illustrated embodiment, the identification circuit 35 includes a comparator CP1, whose positive input is selectively coupled to either the configuration channel pin CC1 or CC2 of the power supply device 10, and whose negative input is coupled to the reference voltage V. REF1 The output terminal is coupled to the control circuit 170.

[0017] exist Figures 3 to 6 In the power transmission system 100 shown, the current detection circuit 140 includes a detection resistor Rs and an amplifier circuit 40, where Vs' represents the voltage across the detection resistor Rs, and Is represents the detection current Is flowing through the detection resistor Rs. The amplifier circuit 40 amplifies the voltage across the detection resistor Rs, Vs', and provides a corresponding detection voltage Vs. When the power supply device 10 and the power receiving device 20 are not yet connected to each other, the load current I... LOADThe value of Rs is 0, therefore the values ​​of the detection current Is and the detection voltage Vs are both 0. After the power supply device 10 is connected to the power receiving device 20, the values ​​of the voltage Vs' across the detection resistor Rs and the detection current Is are related to the load current I. LOAD The amplifier circuit 40 can amplify the voltage Vs' across the sensing resistor Rs to provide the relevant load current I. LOAD The value of the detection voltage Vs.

[0018] exist Figure 3 and Figure 5 In the illustrated embodiment, the current sensing circuit 140 is coupled between the power conversion circuit 110 and the ground pin GND of the source terminal 31, and can be used for low-side current sensing. Figure 4 and Figure 6 In the illustrated embodiment, the sensing resistor Rs is coupled between the power conversion circuit 110 and the switching circuit 120 and can be used for high-side current sensing. However, the implementation of the current sensing circuit 140 does not limit the scope of the present invention.

[0019] exist Figure 3 and Figure 4 In the power delivery system 100 shown, the voltage extraction circuit 150 can measure and store the voltage V on the configuration channel pin CC1 or CC2 of the power supply device 10. CC1 or V CC2 In one embodiment, the voltage extraction circuit 150 may include an analog-to-digital converter and a storage unit for recording the voltage V at different time points. CC1 or V CC2 The value of the voltage V, and the voltage V CC1 or V CC2 The value is converted into a digital signal. In another embodiment, the voltage extraction circuit 150 may include a sample-and-hold circuit and a storage unit for recording the voltage V at different time points. CC1 or V CC2 The value. However, the implementation of the voltage extraction circuit 150 does not limit the scope of the present invention.

[0020] exist Figure 5 and Figure 6 In the power transmission system 100 shown, the voltage extraction circuit 150 can measure and store the voltage V of the signal pin PS in the power supply terminal device 10 that receives external communication signals. DETThe aforementioned signal pin PS can be the D+ pin, D- pin, SBU1 pin, or SBU2 pin as defined in the USB Type-C specification, but is not limited to the scope of this invention. In one embodiment, the voltage extraction circuit 150 may include an analog-to-digital converter and a storage unit for recording the voltage V at different time points. DET The value of the voltage V, and the voltage V DET The value is converted into a digital signal. In another embodiment, the voltage extraction circuit 150 may include a sample-and-hold circuit and a storage unit for recording the voltage V at different time points. DET The value. However, the implementation of the voltage extraction circuit 150 does not limit the scope of the present invention.

[0021] exist Figures 3 to 6 In the power transmission system 100 shown, the current and fault judgment circuit 160 includes comparators CP2 and CP3. The positive input terminal of comparator CP2 is coupled to the output terminal of the voltage extraction circuit 150, and the negative input terminal is coupled to the reference voltage V. REF2 The output is coupled to control circuit 170. The positive input of comparator CP3 is coupled to the output of current detection circuit 140, and the negative input is coupled to reference voltage V. REF3 The output terminal is coupled to the control circuit 170. Based on the voltage V extracted by the voltage extraction circuit 150... CC1 / V CC2 / V DET and reference voltage V REF2 Based on the magnitude relationship, comparator CP2 can output a corresponding signal S2 to control circuit 170. This is based on the detection voltage Vs and reference voltage V provided by current detection circuit 140. REF3 Based on the magnitude relationship, comparator CP3 can output the corresponding signal S3 to control circuit 170.

[0022] exist Figures 3 to 6 In the power transmission system 100 shown, the control circuit 170 controls the operation of the power transmission system 100 according to signals S1-S3. Figure 7 The flowchart of the operation of the power transmission system 100 in this embodiment of the invention includes the following steps, wherein steps 510-540 are performed in the external power-off state (the switching element 120 is off), and steps 540-580 are performed in the external power-on state (the switching element 120 is on).

[0023] Step 510: Power supply device 10 supplies power to its configuration channel pins CC1 / CC2.

[0024] Step 520: Determine whether the power supply device 10 is electrically connected to the power receiving device 20; if yes, proceed to step 530; if no, proceed to step 520.

[0025] Step 530: Record the initial voltage value V1 of the configuration channel pin voltage or signal pin PS of the power supply device 10.

[0026] Step 540: Turn on the switching element 120 after the debounce threshold period.

[0027] Step 550: Measure the current voltage V2 of the configuration channel pin or signal pin PS of the power supply device 10, and monitor the load current I. LOAD The value of .

[0028] Step 560: Determine the load current I LOAD Is the value less than the current threshold? If yes, proceed to step 570; if no, proceed to step 550.

[0029] Step 570: Determine whether the current voltage value V2 of the configuration channel pin voltage or signal pin PS of the power supply device 10 is greater than the initial voltage value V1 and exceeds the voltage threshold ΔV; if yes, proceed to step 580; if no, proceed to step 550.

[0030] Step 580: Implement single fault protection.

[0031] In step 510, the power supply device 10 supplies power to its configuration channel pins CC1 / CC2. In one embodiment, the power supply device 10 can supply power to its configuration channel pins CC1 / CC2 via a voltage source and a resistor to pull the configuration channel pins CC1 / CC2 to a positive bias voltage V+. In another embodiment, the power supply device 10 can supply power to its configuration channel pins CC1 / CC2 via a current source to pull the configuration channel pins CC1 / CC2 to a positive bias voltage V+. However, the manner in which the power supply device 10 supplies power to its configuration channel pins CC1 / CC2 does not limit the scope of the present invention.

[0032] In step 520, the control circuit 170 determines whether the power supply device 10 is electrically connected to the power receiving device 20 based on the signal S1 provided by the device connection detection and identification circuit 130. When the power supply device 10 is not connected to any other device, its configuration channel pins CC1 / CC2 remain at a positive bias voltage V+. Once connected to the transmission line 30 or connected to the power receiving device 20 via the transmission line 30, the configuration channel pins CC1 / CC2 detect the resistor Ra and / or the pull-down resistors RD1 / RD2. Table 1 below shows a schematic diagram of how the power supply device 10 determines its connection status based on its configuration channel pins CC1 / CC2.

[0033]

[0034]

[0035] Table 1

[0036] Since there is only one CC line in transmission line 30, the power supply device 10 can distinguish which configuration channel pin detected the resistance and determine the connection status based on the voltage division on the configuration channel pin. When the power supply device 10 is connected to the power receiving device 20 in a positive insertion manner, the configuration channel pin CC1 of the source end 31 and the configuration channel pin CC2 of the sink end 32 will be connected, while the configuration channel pin CC2 of the source end 31 and the configuration channel pin CC2 of the sink end 32 will be connected. When the power supply device 10 is connected to the power receiving device 20 in a negative insertion manner, the configuration channel pin CC1 of the source end 31 and the configuration channel pin CC2 of the sink end 32 will be connected, while the configuration channel pin CC2 of the source end 31 and the configuration channel pin CC1 of the sink end 32 will be connected. For the sake of simplicity, the present invention will be described using the positive insertion method, while the negative insertion method is similar and will not be described in detail.

[0037] After determining that the power supply device 10 is electrically connected to the power receiving device 20, the current and fault judgment circuit 160 records the voltage V of the configuration channel pin CC1 of the power supply device 10 in step 530. CC1 Or the voltage V of the signal pin PS DET The initial voltage value V1.

[0038] In step 540, the control circuit 170 outputs a switch control signal V after the bounce threshold period has elapsed. G This, in turn, activates the switching element 120. The mechanism of including a bounce threshold period is to prevent connection misjudgments due to external interference; the value of the bounce threshold period can be set according to different applications. In one embodiment, the initial voltage value V1 can be the voltage value recorded at a specific time point within the bounce threshold period on the configuration channel pin CC1 or signal pin PS of the power supply device 10. In another embodiment, the initial voltage value V1 can be the average voltage of the configuration channel pin CC1 or signal pin PS of the power supply device 10 recorded at different time points within the bounce threshold period.

[0039] After the switching element 120 is turned on, the power supply device 10 begins to supply power to the external power receiving device 20 through its power supply pin VBUS. At this time, the current and fault judgment circuit 160 measures the voltage V of the configuration channel pin CC1 of the power supply device 10 in step 550. CC1 Or the voltage V of the signal pin PS DET The current sensing circuit 140 monitors the load current I. LOAD The value of .

[0040] In step 560, the current and fault judgment circuit 160 will determine the load current I. LOAD Is the value less than the current threshold? For example, when the value of the detected voltage Vs is less than the reference voltage V... REF3 When the current and fault judgment circuit 160 is in operation, the comparator CP3 will output a corresponding signal S3 to the control circuit 170 to inform the detection resistor Rs that a short circuit fault may have occurred.

[0041] When the detection current Is flowing through the detection resistor Rs is very small, it indicates that the load of the receiving device 20 is very small, or that the detection resistor Rs has a short circuit fault and cannot provide overcurrent detection. Therefore, in step 570, the present invention will determine which of the above conditions applies.

[0042] In step 570, the voltage V of the configuration channel pin CC1 of the power supply device 10 recorded in step 550 is... CC1 The current voltage V2 of the signal pin PS, and the current and fault judgment circuit 160 will determine whether the current voltage V2 is greater than the initial voltage V1 and exceeds the voltage threshold ΔV. Due to the losses caused by the cable 30, the current voltage V2 obtained under load (switch element 120 is on) will be greater than the initial voltage V1 obtained under no load (switch element 120 is off). The voltage threshold ΔV can reflect the losses caused by the cable 30.

[0043] When determining the load current I in step 560 LOAD When the value is less than the current threshold and it is determined in step 570 that the difference between the current voltage value V2 and the initial voltage value V1 does not exceed the voltage threshold ΔV, it represents the load current I. LOAD The reason for the small value is due to the small load. At this time, the present invention will execute step 550 again to continuously monitor the configuration channel pins CC1 / CC2 or signal pin PS of the power supply device 10.

[0044] When determining the load current I in step 560 LOAD When the value is less than the current threshold and it is determined in step 570 that the difference between the current voltage value V2 and the initial voltage value V1 exceeds the voltage threshold ΔV, it represents the load current I. LOAD The reason for the small value is that the detection resistor Rs has a short circuit fault. At this time, the present invention will perform step 580 to provide single fault protection, such as turning off the switching element 120 to cut off the external power output path of the power supply device 10, so as to avoid component damage caused by the failure of the current detection circuit 140 to detect overcurrent.

[0045] In one embodiment of the present invention, step 560 may be executed earlier than step 570; in another embodiment, step 570 may be executed earlier than step 560; in yet another embodiment, steps 560 and 570 may be executed simultaneously. However, the execution order of steps 560 and 570 does not limit the scope of the present invention.

[0046] In this embodiment of the invention, the negative input terminal of comparator CP3 in the current and fault judgment circuit 160 is coupled to the reference voltage V. REF3 The reference voltage V REF3 The value can be adjusted in different applications, thereby changing the basis for judging overcurrent protection and single fault protection.

[0047] In summary, the power transmission system of the present invention can use a detection circuit to determine whether an overcurrent has occurred in the powered device, thereby providing overcurrent protection. Simultaneously, the present invention can determine whether the current detection circuit has failed based on the configuration channel pins or any signal pins of the power supply device, thereby providing single-fault protection when the current detection circuit is determined to have failed.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

[0049] [Symbol Explanation]

[0050] 10: Power supply terminal device

[0051] 20: Power receiving device

[0052] 30: Transmission line

[0053] 31: Source

[0054] 32: Suction end

[0055] 35: Identification Circuit

[0056] 100: Power transmission system

[0057] 110: Power conversion circuit

[0058] 120: Switching element

[0059] 130: Device connected to detection and identification circuit

[0060] 140: Current detection circuit

[0061] 150: Voltage extraction circuit

[0062] 160: Current and Fault Diagnosis Circuit

[0063] 170: Control Circuit

[0064] 510-580: Steps

[0065] S1-S3: Signals

[0066] V G Switch control signal

[0067] RP1, RP2: Pull-up resistors

[0068] RD1, RD2: Pull-down resistors

[0069] R GND Resistance

[0070] Rs: Sensing resistor

[0071] Vs: Detection voltage

[0072] Vs': Transpressure

[0073] Is: Detected current

[0074] I LOAD Load current

[0075] V CC1 V CC2 V DET : Voltage

[0076] V+: Positive bias voltage

[0077] GND: Ground potential / pin

[0078] V REF1 V REF2 V REF3 Reference voltage

[0079] CP1, CP2, CP3: Comparators

[0080] VBUS: Power supply pins and transmission lines

[0081] VCONN: Cable controller power supply pin

[0082] CC1 / CC2: Configuration channel pins

[0083] CC: Configure channel transmission line

[0084] D+ / D-, SBU1, SBU2: Pins

[0085] TX1+ / TX1-, RX1+ / RX1-,

[0086] TX2+ / TX2-, RX2+ / RX2-: Data transmission pins

[0087] PS: Signal pins

Claims

1. A power transmission system capable of detecting overcurrent and faults, comprising: Power receiving device; Transmission lines; as well as The power supply device includes: First pin; Second pin; Third pin; power conversion circuit, used to supply power to the powered device through the second pin; A switching element is used to selectively turn on or off the power supply path between the power conversion circuit and the second pin according to a switching control signal; The device is connected to a detection and identification circuit to determine whether the power supply device is electrically connected to the power receiving device through the transmission line, and outputs a corresponding first signal. Voltage extraction circuit, used to: During the first period when the power supply device is electrically connected to the power receiving device but no power is supplied to the power receiving device, the initial voltage value of the third pin is recorded; as well as During a second period when the power conversion circuit supplies power to the power receiving device through the second pin, the current voltage value of the third pin is measured; A current sensing circuit is used to monitor the value of the load current during this second period; Current and fault diagnosis circuit, used to: During the second period, it is determined whether the current voltage value is greater than the sum of the initial voltage value and the voltage threshold, and a corresponding second signal is output; as well as During the second period, it is determined whether the value of the load current is less than the current threshold, and a corresponding third signal is output; as well as The control circuit, coupled to the device, connects to the detection and identification circuit and the current and fault judgment circuit to receive the first signal, the second signal, and the third signal, and is used to: When the second signal determines that the current voltage value is greater than the sum of the initial voltage value and the voltage threshold, and the third signal determines that the load current value is less than the current threshold, the switching element is turned off to cut off the power supply path between the power conversion circuit and the second pin.

2. The power transmission system according to claim 1, wherein the control circuit is further configured to: When the power supply device is determined to be electrically connected to the power receiving device based on the first signal, the switching element is turned on after the bounce threshold period, thereby connecting the power supply path between the power conversion circuit and the second pin.

3. The power transmission system according to claim 1, wherein the control circuit is further configured to: When the load current value is determined to be not less than the current threshold based on the third signal, the power conversion circuit is turned off.

4. The power transmission system according to claim 1, wherein the first pin and the third pin are the same pin.

5. The power delivery system according to claim 4, wherein the first pin and the third pin are configuration channel pin CC1 or configuration channel pin CC2 as defined by the Universal Serial Bus (USB) Type-C specification, and the second pin is power supply pin VBUS as defined by the USB Type-C specification.

6. The power delivery system according to claim 1, wherein the first pin is a configuration channel pin CC1 or a configuration channel pin CC2 as defined by the USB Type-C specification, the second pin is a power supply pin VBUS as defined by the USB Type-C specification, and the third pin is a D+ pin, a D- pin, an SBU1 pin, or an SBU2 pin as defined by the USB Type-C specification.

7. The power transmission system according to claim 1, wherein the voltage extraction circuit is further configured to: Multiple voltage values ​​of the third pin are recorded at multiple time points during the first period, and the average value of the multiple voltage values ​​is calculated as the initial voltage value.

8. A method for detecting overcurrent and faults in a power transmission system, comprising: Determine whether the power supply device in the power transmission system is electrically connected to the power receiving device in the power transmission system. During the first period when the power supply device is electrically connected to the power receiving device but no power is supplied to the power receiving device, the initial voltage value of the first pin in the power supply device is recorded; During the second period when the power conversion circuit supplies power to the power receiving device through the second pin, the current voltage value of the first pin and the value of the load current are measured and monitored. as well as When the load current is determined to be less than the current threshold and the current voltage is greater than the sum of the initial voltage and the voltage threshold, the power supply device performs single fault protection to stop supplying power to the power receiving device.

9. The method of claim 8, further comprising: When the third pin of the power supply device detects the fourth pin of the power receiving device, the switching element in the power supply device is turned on after the bounce threshold period, thereby connecting the power conversion circuit in the power supply device to the power supply path of the second pin to supply power to the power receiving device.

10. The method of claim 9, further comprising: When it is determined that the load current is less than the current threshold and the current voltage is greater than the sum of the initial voltage and the voltage threshold, the switching element is turned off to cut off the power supply path from the power conversion circuit to the second pin, thereby performing the single fault protection.

11. The method of claim 9, further comprising: When it is determined that the value of the load current is not less than the current threshold, the power conversion circuit is turned off.

12. The method of claim 9, wherein the first pin and the third pin are the same pin.

13. The method of claim 12, wherein the first pin and the third pin are configuration channel pin CC1 or configuration channel pin CC2 as defined by the Universal Serial Bus (USB) Type-C specification, and the second pin is power supply pin VBUS as defined by the USB Type-C specification.

14. The method of claim 9, wherein the first pin is a D+ pin, D- pin, SBU1 pin or SBU2 pin as defined in the USB Type-C specification, the second pin is a power supply pin VBUS as defined in the USB Type-C specification, and the third pin is a configuration channel pin CC1 or configuration channel pin CC2 as defined in the USB Type-C specification.

15. The method of claim 8, further comprising: Multiple voltage values ​​of the first pin are recorded at multiple time points during the first period, and the average value of the multiple voltage values ​​is calculated as the initial voltage value.

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