An overvoltage protection circuit, a charging interface, a charging cable, and a charging device and a power receiving device

Abstract

An overvoltage protection circuit, charging interface, charging cable, charging device, and power receiving device are disclosed. The overvoltage protection circuit includes a main control chip Type-C interface, the interface including at least one CC pin; a current-limiting resistor, one end of which is connected to the CC pin and the other end to the main control chip; and a voltage regulator module connected in parallel between the current-limiting resistor and the main control chip, one end of which is connected to the connection point between the current-limiting resistor and the main control chip, and the other end is grounded. The voltage regulator module is used to discharge overvoltage current exceeding a preset safety value to ground. In this embodiment of the invention, when leakage or short circuit occurs between the CC pin and VBUS, the voltage of the CC pin can be effectively limited, preventing damage to the main control chip due to overvoltage. Simultaneously, this invention also solves the problems of high cost, large size, and insufficient transient response of existing overvoltage protection chips.

Description

Technical Field

[0001] This invention relates to the field of charging technology, specifically to an overvoltage protection circuit, a charging interface, a charging cable, a charging device, and a power receiving device. Background Technology

[0002] The Type-C interface has become the standard interface for mobile devices such as laptops, smartphones, and tablets because it supports high-power charging, data transmission, and video output. The VBUS power pin of the Type-C interface can withstand voltages of 2.7V-20V or even up to 48V, while the CC communication pin is used to complete device identification, voltage and current negotiation, and is an essential signal channel in the interface. Due to the small size of the Type-C interface and the pin spacing of only 0.25mm, frequent plugging and unplugging of devices during use, as well as the influence of sweat or micro-water droplets, can easily cause leakage or short circuits in the VBUS and CC pins, thereby threatening the safety of the main control chip and the interface.

[0003] In existing technologies, dedicated overvoltage protection chips or parallel voltage regulators are typically used to protect the CC pin from overvoltage. For example, TI's TPD8S300 chip provides reliable overvoltage protection by disconnecting the CC pin in series. Other existing solutions involve adding a TVS, ESD, or Zener diode in parallel between the CC pin and GND for protection. However, these existing solutions suffer from high cost, large size, and insufficient response capability of some devices under high current or high voltage transients, making it difficult to meet the requirements of cost-sensitive products.

[0004] In addition, some parallel schemes have large VBUS capacitors and high current output, which can easily damage the voltage regulator during short circuits, making it impossible to guarantee the stability of the CC signal. Summary of the Invention

[0005] The purpose of this invention is to address the deficiencies and shortcomings of existing technologies by providing an overvoltage protection circuit, a charging interface, a charging cable, and a charging device.

[0006] The technical solution is as follows: In a first aspect, the present invention provides an overvoltage protection circuit, comprising: Main control chip; A Type-C interface, the interface including at least one CC pin; A current-limiting resistor, one end of which is connected to the CC pin, and the other end of which is connected to the main control chip; A voltage regulator module is connected in parallel between the current-limiting resistor and the main control chip. One end of the module is connected to the connection point between the current-limiting resistor and the main control chip, and the other end is grounded. The voltage regulator module is used to discharge overvoltage current exceeding a preset safety value to ground.

[0007] In one embodiment, the voltage regulator module includes a voltage regulator unit, which is at least one of a light-emitting diode, a Zener diode, a discharge diode, a trigger diode, and a parallel voltage regulator.

[0008] In one embodiment, a bypass capacitor is further included, which is connected in parallel with the current-limiting resistor.

[0009] In one embodiment, the bypass capacitor has a capacitance of 1nF-100uF and a voltage rating of 6.3V-50V.

[0010] In one embodiment, the current-limiting resistor has a resistance value of 10R-470R.

[0011] In one embodiment, the voltage regulator unit is a 3.3V discharge diode.

[0012] Secondly, the present invention provides a Type-C charging interface, including a charging interface body and an overvoltage protection circuit as described above, wherein the charging interface body is a male or female connector.

[0013] Furthermore, when the charging interface body is a female connector, the present invention also includes a bypass diode, wherein the anode of the bypass diode is connected to the other end of the current limiting resistor and the main control chip, and the cathode of the bypass diode is connected to the CC pin of the Type-C interface.

[0014] Thirdly, the present invention provides a charging cable including the overvoltage protection circuit described above.

[0015] Fourthly, the present invention provides a charging device including the overvoltage protection circuit described above.

[0016] Fifthly, the present invention provides a power receiving device, including the overvoltage protection circuit described above.

[0017] This invention discloses an overvoltage current exceeding a preset safety value by connecting a current-limiting resistor in series between the CC pin of the Type-C interface and the main control chip, and a voltage regulator module in parallel between the current-limiting resistor and the main control chip. This effectively limits the voltage of the CC pin when leakage or short circuit occurs between the CC pin and VBUS, thus preventing the main control chip from being damaged by overvoltage.

[0018] Meanwhile, the present invention has a simple structure, consisting only of a main control chip, a CC pin, a current limiting resistor, and a voltage regulator module. It does not require the use of a dedicated overvoltage protection chip or a large-volume voltage regulator, which saves costs and reduces circuit size. It is suitable for use in cost-sensitive and space-constrained devices. It can solve the problems of high cost, large size and insufficient transient response of overvoltage protection chips in the prior art, while ensuring the safety and stability of the CC signal and improving the reliability of the Type-C interface in frequent plugging and unplugging and humid environments. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the female connector pinout of the Type-C interface; Figure 2 This is a circuit block diagram of an embodiment of the present invention; Figure 3 This is a circuit block diagram of another embodiment of the present invention; Figure 4 This is a circuit block diagram of another embodiment of the present invention; Figure 5 This invention relates to the test circuit and measured waveforms when VBUS and CC are short-circuited at 20V.

[0021] Figure label: 100. Type-C interface; 200. Main control chip; 300. Voltage regulator module; R1, current-limiting resistor; C1, bypass capacitor; D1, bypass diode; Z1, Discharge diode. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] Reference Figure 1 The female connector pinout of the USB-C interface consists of two rows of symmetrical pins, labeled as group A (A1-A12) and group B (B1-B12). The pins and their functions relevant to this invention are described below: VBUS (A4, A9, B4, B9 pins) are power supply pins that provide a voltage output from 5V to -48V to power connected devices.

[0027] CC1 (pin A5) and CC2 (pin B5) are important pins in the USB-C interface used for power delivery negotiation (USB Power Delivery, PD) and fast charging protocol identification. The CC switching circuit of this invention is connected to these two pins respectively to realize the switching and transmission of CC signals.

[0028] It should be noted that although the above description only mentions the pin distribution of the female connector of the USB-C interface, the design of the present invention is also applicable to the male connector of the USB-C interface. The male and female connectors of the USB-C interface have the same pin functions and arrangement, only the connection method is different.

[0029] The Type-C interface includes 12 pins on both the A and B sides. A4, A9, B4, and B9 are VBUS power pins, with a maximum voltage of 20V under the PD2.0 specification and supporting up to 48V under the PD3.1 specification. A5 and B5 are communication pins, namely Configuration Channel (CC). A5 is defined as CC1, and B5 as CC2. These two pins are essential in all applications of the Type-C interface, used for negotiating and configuring voltage, current, USB 3.2 data stream, and DP Altmode video stream. The maximum supported voltage is generally 5.5V~6V. In the Type-C interface, the center-to-center spacing between pins is 0.5mm, the pin width itself is 0.25mm, and the insulation spacing between pins is only 0.25mm.

[0030] In daily use, because the Type-C interface simultaneously handles charging, data transfer, audio, and video functions, and mobile devices such as smartphones, tablets, and laptops are frequently carried and plugged in and out, foreign objects, sweat, or trace amounts of water may enter the interface, potentially causing leakage between the VBUS pin and the adjacent CC pin. Furthermore, friction during insertion and removal may generate metal particles on the pin surface, leading to a decrease in insulation; or lateral stress caused by misalignment during insertion or removal may accumulate over time, increasing the interface gap and causing slight deformation of the pin or casing. All of these factors can potentially cause a short circuit between the VBUS pin and the CC pin.

[0031] If leakage occurs between the VBUS and CC pins and the current reaches the mA level, it may damage the main control chip connected to the CC pin, thus harming the device. To address this issue, the TPD8S300 chip released by Texas Instruments in 2016 can protect the CC pin in series, quickly disconnecting it when an overvoltage is detected, providing reliable protection. Other existing solutions use parallel voltage regulators, adding a TVS or Zener diode between the CC pin and GND for protection. However, these solutions typically suffer from high cost, large size, and insufficient response under high current or transient overvoltage conditions, making them unsuitable for cost-sensitive or space-constrained products. Furthermore, some parallel solutions are prone to damaging the voltage regulator when the VBUS current is large and the power supply capacitance is high, failing to guarantee the stability of the CC signal.

[0032] When the PD power supply outputs 20V and has a 2200uF or larger capacitor at the output, the voltage across the capacitor can drop below 6.5V within 50 nanoseconds during discharge. For this transient high-current and rapid discharge scenario, existing voltage regulators are expensive (e.g., over 1 RMB) and bulky, making them unsuitable for cost-sensitive applications.

[0033] For example, the commercially available, high-performance TI TVS0500 device has strong surge suppression capabilities, with a dynamic internal resistance far lower than that of conventional large-volume SMA or SMB series TVS devices. However, when a short circuit occurs between the CC pin and VBUS and is used for parallel protection, the device may still fail to withstand transient overvoltages due to the large capacitance of the PD power supply output capacitor, continuous current output, and the combined effects of the switching circuit power supply, posing a risk of damage. Therefore, it is evident that existing devices struggle to balance cost and reliability under high capacitance and high current transient conditions, limiting their application in low-cost mobile devices.

[0034] Reference Figure 2 To address the shortcomings of existing technologies, this invention provides an overvoltage protection circuit, comprising: Main control chip 200; Type-C interface 100, the interface including at least one CC pin; The current-limiting resistor R1 has one end connected to the CC pin and the other end connected to the main control chip 200. A voltage regulator module 300 is connected in parallel between the current limiting resistor R1 and the main control chip 200. One end of the module is connected to the connection point between the current limiting resistor R1 and the main control chip 200, and the other end is grounded. The voltage regulator module 300 is used to discharge overvoltage current exceeding a preset safety value to ground.

[0035] In this embodiment, when the CC pin at the Type-C interface 100 receives a high-voltage input, the high-voltage current is first limited by the current-limiting resistor R1 and then sent to the voltage regulator module 300. It presents extremely low impedance to currents exceeding its voltage limit, discharging the overvoltage current to ground, thereby ensuring that the voltage across both ends remains within a safe range and preventing damage to the CC pin of the connected main control chip 200 due to overvoltage. As a PD source, when it detects that the CC pin voltage is much higher than the normal handshake voltage, the PD source identifies this CC voltage as a sink disconnection and adjusts the output voltage to 5V within a maximum of 275 milliseconds according to the PD2.0 specification. Therefore, this embodiment ensures that when leakage or a short circuit occurs between the CC pin and VBUS, the CC pin on the main control chip 200 side will not continuously bear high voltage, thus achieving overvoltage protection for the CC pin.

[0036] In one embodiment, the voltage regulator module 300 includes a voltage regulator unit, which is at least one of a light-emitting diode, a Zener diode, a discharge diode, a trigger diode, and a parallel voltage regulator.

[0037] Preferred, refer to Figure 3 The voltage regulator unit is a 3.3V discharge diode in a metric DFN1006 package.

[0038] Reference Figure 4 In one embodiment, a bypass capacitor C1 is also included. The bypass capacitor C1 is connected in parallel with the current-limiting resistor R1. When VBUS and CC are short-circuited, a large current flows through the bypass capacitor C1 to the voltage regulator unit. If ordinary voltage regulator devices are used, they may not be able to withstand this transient current, resulting in insufficient voltage regulation performance. Therefore, the voltage regulator unit needs to have a low clamping voltage under high current conditions to ensure that the CC pin and the main control chip 200 are not damaged by overvoltage. The voltage regulator unit also needs to have low dynamic impedance so that the bypass capacitor C1 can quickly complete charging, allowing the clamping voltage to return to a safe value in a timely manner.

[0039] Preferably, when the bypass capacitor C1 is present, an ESD device with a clamping voltage Vc of 5V~6V and VRWM>2.7V can be used to ensure the safety of the CC pin during transient overvoltage. It should be noted that the bypass capacitor C1 is used when the current-limiting resistor R1 has a relatively large resistance (when the size of the current-limiting resistor R1 is limited, a larger resistance should be chosen) to prevent it from affecting signal stability. C1 provides a low-impedance bypass path for the signal, so the bypass capacitor C1 is not essential. If needed, its capacitance value is recommended to be between 10nF and 0.1uF, and its voltage rating between 6.3V and 50V. In one embodiment, the resistance value of the current-limiting resistor R1 is typically between 10Ω and 470Ω to ensure that when the VBUS of the Type-C interface 100 is directly short-circuited to the CC pin, the voltage regulator can stabilize the voltage below the maximum allowable voltage of the CC pin of the PD chip, and ensure that the resistance value of the current-limiting resistor R1 changes by less than 20% when the VBUS is at its maximum voltage and short-circuited to CC for 0.5 seconds. When a higher resistance value of the current-limiting resistor R1 is selected, its lifespan under maximum overvoltage input conditions can be improved, but an excessively high resistance value may affect the communication stability of the CC signal. With the resistance value unchanged, increasing the rated power of the current-limiting resistor R1 can extend its lifespan in overvoltage protection, but increasing the rated power usually occupies more PCB space. If a smaller current-limiting resistor R1 is desired under normal voltage conditions, while a longer lifespan is desired under overvoltage conditions, there seems to be a contradiction. This can be resolved by using a PTC type fuse. When the CC pin voltage is within the normal range, the PTC fuse has a smaller resistance; when the voltage is too high and the current reaches the threshold, the PTC resistance increases significantly, and under the action of the voltage regulator, the protected CC pin voltage is kept within a safe range.

[0040] Reference Figure 4 Secondly, the present invention provides a Type-C interface 100 (not distinguishing between charging device and receiving device), including an interface body and an overvoltage protection circuit as described above, wherein the interface body is a male or female connector.

[0041] Furthermore, when the interface body is a female connector, the present invention also includes a bypass diode D1, the anode of the bypass diode D1 is connected to the other end of the current limiting resistor R1 and the main control chip 200, and the cathode of the bypass diode D1 is connected to the CC pin of the Type-C interface 100.

[0042] It should be noted that the bypass diode D1 is an optional component, used only when the Type-C interface 100 is the female connector and this interface can be used as a PD source to power the host. In this case, the corresponding CC pin needs to act as Vconn to power the cable. When the Type-C female connector may be connected to an Active Cable with signal resetting function, a Schottky diode with a rated current of 300mA or higher should be selected. If signal resetting function is not required, a general-purpose diode can be used. When the CC pin is used as Vconn to power a regular cable, the resistance of R1 can be appropriately reduced to about 47Ω. In this case, the bypass diode D1 can be omitted. The selection of the current-limiting resistor R1 and the voltage regulator unit are mutually restrictive. In practical applications, the most suitable combination should be selected according to the product's tolerance for performance, cost, and PCB space. This is done to achieve circuit miniaturization and a cost of less than 0.05 RMB.

[0043] Preferably, the current-limiting resistor R1 is a 100Ω imperial 0603 chip resistor, the bypass capacitor C1 is a 47nF 10V 0201 chip capacitor, and the discharge diode Z1 is a metric DFN1006 packaged ESD device with a VBR of approximately 3.3V and Vc < 5.5V @ 0.3A.

[0044] Reference Figure 5 This embodiment demonstrates an actual test of the overvoltage protection circuit for the 100 CC pin of the Type-C interface. The test environment is as follows: The PD source voltage is 20V, the output current is 5A, and the output terminal Cout capacitor is 2200uF; The current-limiting resistor R1 and the bypass capacitor C1 are respectively selected as 100Ω surface mount resistor and 0.1µF surface mount capacitor (L0.5mm×W0.25mm) in 0201 package. The voltage regulator unit Z1 uses a 3.3V ESD device in a metric DFN1006 package, with Vc=5.5V (1A) and VRWM=3.3V; The female bypass diode D1 is not in use; The total component cost of R1, C1, and Z1 is less than 0.05 RMB.

[0045] Furthermore, during the test, when 20V VBUS and CC are short-circuited, the waveform changes as follows: a)t0: VBUS and CC are short-circuited, and the voltage of CC pin starts to rise. However, due to the limitations of the short-circuit contact resistance and the filter capacitor between CC and GND, and combined with the voltage regulation effect of C1 and Z1, the voltage of CC pin does not rise directly to 20V. b)t1: During the high-current charging process, the voltage change of C1 is limited. At the same time, the high current flows through C1 to the input terminal of Z1. Due to the increase in current, the voltage of Z1 rises briefly to about 7V, but the duration in the range of 6V~7V is very short (<50 nanoseconds). c)t2: C1 is fully charged, and the current no longer flows into Z1. The voltage of Z1 drops rapidly to the regulated voltage Vc under microcurrent conditions. d)t3: The CC pin of the interface remains shorted to VBUS, but there is almost no current flowing through C1, and the voltage of Z1 remains at about 5V. e)t4: About 14 milliseconds after VBUS and CC are short-circuited, the PD power controller detects that the voltage on the CC pin is higher than 2.7V, identifies this state as the CC interface being unplugged, and shuts off the VBUS voltage output; f) At this point, the overvoltage protection process of the CC pin is complete, ensuring the safety of the main control chip 200 and the connecting circuit.

[0046] As can be seen from this embodiment, the CC pin overvoltage protection circuit provided by the present invention can stably limit the CC voltage under high current, large capacitance and short-circuit transient conditions, ensuring safe and reliable operation.

[0047] Thirdly, the present invention provides a charging cable including the overvoltage protection circuit as described above. The overvoltage protection circuit is arranged at the CC pin end of the charging cable and can provide overvoltage protection for the CC pin of the connected PD main control chip 200, thereby ensuring the safety of the charging cable and the connected device when leakage or short circuit occurs between the CC pin and VBUS.

[0048] Fourthly, the present invention provides a charging device and a receiving device, characterized in that it includes the overvoltage protection circuit described above. The charging device can be a PD power adapter, a power bank, or other power supply device with a Type-C interface 100, and the receiving device can receive power through the Type-C interface 100. By integrating this overvoltage protection circuit, when an abnormal high voltage or short circuit occurs between the CC pin and VBUS, the voltage of the CC pin can be quickly limited, preventing damage to the downstream main control chip 200 and circuits, and improving the safety and reliability of the charging device.

[0049] The above is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. An overvoltage protection circuit, characterized in that, include: Main control chip (200); A Type-C interface, the interface including at least one CC pin; A current-limiting resistor (R1) is connected at one end to the CC pin and at the other end to the main control chip (200). A voltage regulator module (300) is connected in parallel between the current limiting resistor (R1) and the main control chip (200). One end of the module is connected to the connection point between the current limiting resistor (R1) and the main control chip (200), and the other end is grounded. The voltage regulator module (300) is used to discharge overvoltage current exceeding a preset safety value to ground.

2. The overvoltage protection circuit according to claim 1, characterized in that, The voltage regulator module (300) includes a voltage regulator unit, which is at least one of a light-emitting diode, a Zener diode, a discharge diode, a trigger diode, and a parallel voltage regulator.

3. The overvoltage protection circuit according to claim 1, characterized in that, It also includes a bypass capacitor (C1), which is connected in parallel with the current-limiting resistor (R1).

4. The overvoltage protection circuit according to claim 3, characterized in that, The bypass capacitor (C1) has a capacitance of 1nF-100uF and a voltage rating of 6.3V-50V.

5. The overvoltage protection circuit according to claim 1, characterized in that, The current-limiting resistor (R1) has a resistance value of 10R-470R.

6. The overvoltage protection circuit according to claim 2, characterized in that, The voltage regulator unit is a 3.3V Zener diode.

7. A Type-C charging interface, characterized in that, It includes a charging interface body and an overvoltage protection circuit as described in any one of claims 1-6, wherein the charging interface body is a male or female connector.

8. The Type-C charging interface according to claim 7, characterized in that, When the charging interface body is a female connector, it also includes a bypass diode (D1). The anode of the bypass diode (D1) is connected to the other end of the current limiting resistor (R1) and the main control chip (200), and the cathode of the bypass diode (D1) is connected to the CC pin of the Type-C interface.

9. A charging cable, characterized in that, Includes the overvoltage protection circuit as described in any one of claims 1-6.

10. A charging device, characterized in that, Includes the overvoltage protection circuit as described in any one of claims 1-6.

11. A power receiving device, characterized in that, Includes the overvoltage protection circuit as described in any one of claims 1-6.

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