Dumb protection circuit and method for type-c charging port of device with base charging

Abstract

The application belongs to the field of electronic equipment charging and relates to a foolproof protection circuit and method for a TypeC charging port of a device with a base, comprising: a TypeC interface module for connecting an external TypeC device; a POGO interface module for connecting a charging base and receiving power signals and communication signals input by the base; a power path switching module for controlling the charging power path to switch between a TypeC path and a POGO path; a USB signal switching module electrically connected with the TypeC interface module, the POGO interface module and a master CPU respectively, for controlling a USB signal path to switch between a TypeC path and a POGO path; a CC protocol identification module electrically connected with the TypeC interface module; and a power supply module for providing working power for the USB signal switching module and the CC protocol identification module. The circuit is automatically foolproof and has high safety.

Description

Technical Field

[0001] This invention relates to the field of electronic device charging technology, and more specifically, to a foolproof protection circuit and method for a Type-C charging port of a device with a charging dock. Background Technology

[0002] With the widespread use of electronic devices and the continuous development of charging technology, users are demanding increasingly higher levels of convenience and efficiency in charging their devices. Currently, most handheld devices on the market, such as POS terminals, only support conventional slow charging, and their charging interfaces are limited to a single type: DC, USB, or a charging dock. This results in not only low charging efficiency but also the need for frequent plugging and unplugging of the charging cable, making the process cumbersome.

[0003] In real-world applications of devices such as POS machines, these devices are frequently used and typically placed on a charging dock for recharging when idle. Existing charging solutions struggle to balance ease of use with battery life requirements. Some devices attempt to integrate a Type-C port and dock charging functionality, but this presents a critical issue: when the device is charging at 9V via the dock, the Type-C port remains powered. If an external device (such as a USB flash drive or mobile phone) is connected to the Type-C port at this time, the high voltage from the dock may be reversed through the Type-C port, potentially damaging the external device.

[0004] To address the aforementioned issues, existing technologies often employ additional foolproof structures (such as mechanical foolproof slots or irregularly shaped interfaces) to achieve foolproof functionality. However, these solutions frequently require alterations to the product's appearance, increasing design complexity and impacting aesthetics and user experience. Furthermore, mechanical foolproof structures are susceptible to wear and tear after prolonged use, resulting in limited reliability.

[0005] Therefore, there is an urgent need in this field for a Type-C charging port foolproof protection solution that can automatically implement foolproof protection at the circuit level, without modifying the product appearance, and has high reliability. Summary of the Invention

[0006] To address the aforementioned deficiencies in the prior art, this invention provides a foolproof protection circuit for the Type-C charging port of a device with a charging dock, comprising: The Type-C interface module is used to connect external Type-C devices and supports Type-C protocol communication and PD charging protocol. The POGO interface module is used to connect to the charging dock and receive power and communication signals input from the dock. The power path switching module is electrically connected to the Type-C interface module and the POGO interface module respectively, and is used to control the switching of the charging power path between the Type-C path and the POGO path. The USB signal switching module is electrically connected to the Type-C interface module, the POGO interface module and the main control CPU respectively, and is used to control the switching of the USB signal path between the Type-C path and the POGO path. The CC protocol identification module is electrically connected to the Type-C interface module and is used to identify the type of device inserted into the Type-C interface and the PD charging protocol. The power supply module is electrically connected to the USB signal switching module and the CC protocol identification module respectively, and is used to provide working power to the USB signal switching module and the CC protocol identification module; The main control CPU is electrically connected to the power path switching module, the USB signal switching module and the POGO interface module respectively. Based on the dock insertion detection signal of the POGO interface module, it controls the power path switching module and the USB signal switching module to perform path switching.

[0007] Preferably, the power path switching module includes: The overvoltage protection chip U100 has its input terminal connected to the VBUS pin of the Type-C interface to monitor the Type-C power input voltage. When the input voltage exceeds the preset protection threshold, the power path is cut off. The first PMOS transistor Q100 and the second PMOS transistor Q101 are connected. The source of the first PMOS transistor Q100 is connected to the output terminal of the overvoltage protection chip U100, the drain is connected to the main power supply terminal VBUS of the device, and the gate is connected to the drain of the second PMOS transistor Q101. The source of the second PMOS transistor Q101 is connected to the output terminal of the overvoltage protection chip U100, and the gate is connected to the OTG_POWER_EN control signal terminal of the main control CPU and the POGO_IDDIG signal terminal of the POGO interface module (20), respectively. The first bias resistor R100 is connected between the gate and source of the second PMOS transistor Q101 to provide the gate bias voltage. The first voltage divider resistor R101 and the second voltage divider resistor R103 are connected in series between the voltage setting terminal of the overvoltage protection chip U100 and ground, and are used to set the overvoltage protection threshold voltage.

[0008] Preferably, the overvoltage protection threshold voltage of the overvoltage protection chip U100 is set by the following formula: ; in, This is the overvoltage protection threshold voltage. This is the internal reference voltage of the overvoltage protection chip U100. The resistance value of the first voltage divider resistor is... The resistance value of the second voltage divider resistor; The resistance values ​​of the first voltage divider resistor R101 and the second voltage divider resistor R103 are configured such that the overvoltage protection threshold voltage is 10.5V to match the PD 9V / 2A charging specification.

[0009] Preferably, the first PMOS transistor Q100 has a parasitic body diode, the positive terminal of which is connected to the source of the first PMOS transistor Q100, and the negative terminal is connected to the drain of the first PMOS transistor Q100. When the first PMOS transistor Q100 is in the off state, the parasitic diode forms a unidirectional conductive path, allowing current to flow from the Type-C interface to the device's main power supply terminal VBUS, while blocking the reverse current path.

[0010] Preferably, when the OTG_POWER_EN signal terminal of the main control CPU outputs a high level, the second PMOS transistor Q101 is turned on, thereby driving the first PMOS transistor Q100 to be turned on, so that the Type C power path is connected. When the OTG_POWER_EN signal terminal of the main control CPU outputs a low level, the second PMOS transistor Q101 is turned off, the first PMOS transistor Q100 is turned off, and the Type C power path is turned off.

[0011] Preferably, the POGO interface module includes: The POGO power input terminal POGO_VBUS is used to connect to the base power output; The POGO interrupt signal terminal POGO_INT is connected to the interrupt input terminal of the main control CPU and is used to send a low-level insertion detection signal to the main control CPU when the device is placed in the base. The POGO identification signal terminal POGO_IDDIG is connected to the power path switching module and is used to hardware-shut down the power path switching module by a low-level signal when the device is placed in the base. The common-mode inductor L200 is connected in the POGO data signal path to suppress common-mode interference; The first electrostatic discharge protection tube group T200, T201, T202, and T203 are respectively connected between the POGO data signal line and ground for electrostatic discharge protection; The surge protection tube D200 is connected between the POGO power input terminal and ground for surge protection. The filter capacitor C200 is connected in parallel between the POGO power input terminal and ground for power filtering. The self-resetting fuse resistor R202 is connected in series with the POGO power input terminal for overcurrent protection.

[0012] Preferably, the USB signal switching module includes a USB signal switching chip, whose first signal path is connected to the USB signal terminal of the Type-C interface module, the second signal path is connected to the USB signal terminal of the POGO interface module, and the common signal terminal is connected to the USB signal terminal of the main control CPU. The channel selection control terminal of the USB signal switching chip is connected to the USB_SIGNAL_SW control signal terminal of the main control CPU. When the main control CPU detects that the dock is inserted, the USB_SIGNAL_SW control signal terminal outputs a low level, controlling the USB signal switching chip to switch the USB signal path from the Type C path to the POGO path.

[0013] Preferably, the Type-C interface module includes: The Type-C socket has its VBUS pin connected to the power path switching module, its CC1 and CC2 pins connected to the CC protocol identification module, and its D+ and D- pins connected to the USB signal switching module. The second electrostatic discharge protection tube group T300, T301, T302, and T303 are connected between the Type-C data signal line and ground, respectively, for electrostatic discharge protection. The surge protector D300 is connected between the VBUS pin of the Type-C connector and ground for surge protection. The filter capacitor C300 is connected in parallel between the VBUS pin of the Type-C circuit and ground for power supply filtering. The common-mode inductor L300 is connected in series in the Type-C data signal path to suppress common-mode interference.

[0014] Preferably, the CC protocol identification module includes a CC protocol chip, wherein the CC1 terminal and the CC2 terminal of the CC protocol chip are respectively connected to the CC1 pin and the CC2 pin of the Type-C interface module; The CC protocol chip is used to identify the type of device connected to the Type-C interface, including OTG devices, PD charging devices and C-to-C data devices, and transmits the identification result to the main control CPU through the communication interface.

[0015] On the other hand, the present invention also provides a method for preventing the mistakenly connected circuit of the Type-C charging port using the above-mentioned charging device with a charging dock, comprising the following steps: Step S1: When the device is in standby mode, the Type C power path and POGO power path of the power path switching module are both in the default off state. The parasitic diode of the Type C interface module (30) forms a unidirectional conductive path, enabling the Type C interface to send a USB insertion detection signal to the main control CPU. Step S2: When a Type-C device is inserted, the main control CPU detects the USB insertion signal and outputs an OTG_POWER_EN high-level enable signal to the power path switching module, driving the first PMOS transistor Q100 and the second PMOS transistor Q101 to conduct, connecting the Type-C power path, so that power flows from the Type-C interface to the device's main power terminal VBUS. Step S3: When the device is placed in the charging dock, the POGO_INT signal terminal of the POGO interface module is pulled low by the dock. The main control CPU detects this low-level signal and determines that the device has been placed in the dock. Step S4: The main control CPU pulls the OTG_POWER_EN signal from high level to low level, which turns off the first PMOS transistor Q100 and the second PMOS transistor Q101, shutting down the Type C power path. At the same time, the POGO_IDDIG signal is pulled low, and the hardware forces the second PMOS transistor Q101 to shut down, forming a dual protection of hardware and software. Step S5: Power flows from the POGO_VBUS input terminal of the POGO interface module to the main power terminal VBUS of the device to charge the device. At the same time, the Type C power path is cut off to prevent the 9V voltage of the base from being output in reverse to the external device through the Type C interface. Step S6: The main control CPU controls the USB signal switching module through the USB_SIGNAL_SW control signal terminal to switch the USB signal path from the Type C path to the POGO path, so that the dock's USB peripheral can be connected to the device. Step S7: When the device leaves the dock, the POGO_INT signal returns to a high level. The main control CPU detects this state change, controls the USB signal switching module to restore the USB signal path to the Type C path, and waits for the Type C device to be inserted to reconnect the Type C power path.

[0016] The foolproof protection circuit for the Type-C charging port in the device with charging dock of the present invention has the following advantages: (1) Automatic error prevention and high safety: The PMOS switching network of the power path switching module 10, together with the software control of the main control CPU and the hardware control of POGO_IDDIG, realizes a dual redundant shutdown mechanism for the Type C power path. When the device is placed in the dock, even if the control signal of the main control CPU is abnormal due to software failure, the hardware control signal of POGO_IDDIG can still independently shut down the power path, ensuring that there is absolutely no voltage output from the Type C interface, fundamentally avoiding the risk of the 9V voltage of the dock burning out the Type C external device.

[0017] (2) No need to modify the product appearance, maintaining aesthetics: In the prior art, the error prevention function is mostly achieved through mechanical error prevention structure, which requires changes to the product appearance and increases design complexity. The present invention achieves error prevention protection through pure circuit design, without any changes to the overall appearance of the machine, and the original appearance and aesthetics of the product are completely preserved. Moreover, the relevant circuit structure is hidden inside the device, with good concealment and does not affect the user experience.

[0018] (3) Supports full-function standard Type-C with good compatibility: The Type-C interface module 30 supports the standard Type-C protocol and PD charging protocol. Users can use a standard Type-C port charger to charge the device, insert it into a computer to transfer data, and use a Type-C USB flash drive. The CC protocol identification module 50 supports the identification of various device types such as OTG devices, PD charging devices, and C-to-C data devices, and has good compatibility.

[0019] (4) Automatic dual-path switching for ease of use: Automatic identification and switching between the Type-C charging path and the dock charging path are realized. After the user places the device on the dock, the charging path automatically switches to the dock, and the USB signal path automatically switches to the dock peripheral, without the need for manual operation by the user, thus improving the ease of use.

[0020] (5) Simple circuit structure and controllable cost: By using discrete components, there is no need to customize dedicated chips. The components are widely available and the cost is controllable. At the same time, the circuit structure is relatively simple and easy to integrate into the motherboard of existing equipment, with good manufacturability and scalability. Attached Figure Description

[0021] 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 the structures shown in these drawings without creative effort. The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings: Figure 1 This is a schematic diagram of the module configuration of the foolproof protection circuit for the Type-C charging port of the device with charging base of the present invention. Figure 2 This is a circuit diagram of the power path switching module 10 in the foolproof protection circuit for the Type-C charging port of the device with charging base of the present invention. Figure 3 This is a circuit diagram of the POGO interface module 20 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 4 This is a circuit diagram of the TypeC interface module 30 in the foolproof protection circuit for the TypeC charging port of the device with charging dock of the present invention. Figure 5 This is a circuit diagram of the USB signal switching module 40 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 6 This is a circuit diagram of the CC protocol identification module 50 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 7 This is a circuit diagram of the power supply module 60 in the foolproof protection circuit for the Type-C charging port of the device with charging base of the present invention.

[0022] In the diagram, 10 is the power path switching module, 20 is the POGO interface module, 30 is the Type-C interface module, 40 is the USB signal switching module, 50 is the CC protocol identification module, and 60 is the power supply module. Detailed Implementation

[0023] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0025] POGO refers to POGO Pin (spring-loaded pin / probe connector), a precision connector consisting of a spring-loaded pin and contacts. Its name comes from the English word "Pogo," which vividly describes the elastic physical characteristic of the spring inside the pin.

[0026] In the following embodiments, the POGO interface module refers to the metal contact interface through which the device connects to the charging dock via magnetic attraction or snap-fit. Its main features include: Physical characteristics: The POGO Pin consists of a needle, a spring, and a tube, and has excellent electrical contact performance and shock resistance.

[0027] Charging applications: POGO interfaces are commonly used in dock-based charging scenarios. When a device is placed on the dock, an electrical connection for power and signal is established through the POGO contacts, enabling "placing and charging".

[0028] The difference between Type-C and POGO: Type-C is a universal pluggable interface, while POGO is a custom contact interface specifically designed for dock charging. When a device has both, a circuit is needed to prevent the Type-C port from outputting reverse voltage when the dock is charging. This is the core problem that this invention solves.

[0029] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0030] Example 1 Please see Figure 1 This is a schematic diagram of the module configuration of the foolproof protection circuit for the Type-C charging port of the device with a charging dock according to the present invention. Figure 1 As shown, the foolproof protection circuit for the Type-C charging port of the device with charging dock provided in the first embodiment of the present invention includes at least a Type-C interface module 30, which is used to connect to an external Type-C device and supports Type-C protocol communication and PD charging protocol. POGO interface module 20 is used to connect to the charging dock and receive power signals and communication signals input from the dock; The power path switching module 10 is electrically connected to the TypeC interface module 30 and the POGO interface module 20 respectively, and is used to control the switching of the charging power path between the TypeC path and the POGO path. The USB signal switching module 40 is electrically connected to the TypeC interface module 30, the POGO interface module 20 and the main control CPU respectively, and is used to control the switching of the USB signal path between the TypeC path and the POGO path. The CC protocol identification module 50 is electrically connected to the Type-C interface module 30 and is used to identify the type of device inserted into the Type-C interface and the PD charging protocol. The power supply module 60 is electrically connected to the USB signal switching module 40 and the CC protocol identification module 50 respectively, and is used to provide working power to the USB signal switching module 40 and the CC protocol identification module 50. The main control CPU is electrically connected to the power path switching module 10, the USB signal switching module 40 and the POGO interface module 20 respectively. Based on the base insertion detection signal of the POGO interface module 20, it controls the power path switching module 10 and the USB signal switching module 40 to perform path switching.

[0031] Figure 2 This is a circuit diagram of the power path switching module 10 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 2 As shown, the power path switching module 10 includes: (1) Overvoltage protection chip U100: The commercially available OVP (Over Voltage Protection) chip is used, which integrates a voltage comparator, a reference voltage source and a power switch. The input terminal IN of U100 is connected to the VBUS pin of the TypeC interface to monitor the TypeC power input voltage. When the input voltage exceeds the preset protection threshold, the power path is cut off. The output terminal OUT of U100 is connected to the subsequent PMOS transistor circuit, the enable terminal EN is connected to the corresponding control pin of the device's main control CPU, and the voltage setting terminal VSET is connected to the voltage divider resistor network.

[0032] (2) The first PMOS transistor Q100 is a P-channel enhancement-mode MOSFET. Its source S is connected to the output terminal of the overvoltage protection chip U100, its drain D is connected to the main power supply terminal VBUS of the device, and its gate G is connected to the drain of the second PMOS transistor Q101. There is a parasitic diode D_Q100 inside Q100, whose positive terminal is connected to the source and its negative terminal is connected to the drain.

[0033] (3) The second PMOS transistor Q101 is a P-channel enhancement-type MOSFET. Its source S is connected to the output terminal of the overvoltage protection chip U100, and its drain D is connected to the gate of Q100. The gate G is connected to the source through the first bias resistor R100, to the OTG_POWER_EN control terminal of the main control CPU through the signal line, and to the POGO_IDDIG terminal of the POGO interface module through the signal line.

[0034] (4) First bias resistor R100: connected between the gate and source of Q101 to provide gate bias voltage for Q101, so that Q101 remains in the off state when there is no control signal.

[0035] (5) First voltage divider resistor R101 and second voltage divider resistor R103: connected in series between the voltage setting terminal VSET of the overvoltage protection chip U100 and ground to form a voltage divider network, which is used to set the overvoltage protection threshold voltage.

[0036] (6) First filter capacitor C103 and second filter capacitor C105: respectively connected between the input terminal and ground of the overvoltage protection chip U100 and between the output terminal and ground, to filter out power supply ripple and ensure stable chip operation.

[0037] The input terminal IN of the overvoltage protection chip U100 is electrically connected to the VBUS pin of the Type-C interface module 30; The output terminal OUT of the overvoltage protection chip U100 is electrically connected to the source of Q100 and the source of Q101, respectively. The voltage setting terminal VSET of the overvoltage protection chip U100 is electrically connected to one end of the voltage divider resistor R101; The other end of the first voltage divider resistor R101 is electrically connected to one end of the second voltage divider resistor R103, and the other end of R103 is grounded. The source of Q100 is connected to the source of Q101, the gate of Q100 is connected to the drain of Q101, and the drain of Q100 is connected to the main power supply terminal VBUS of the device. The gate of Q101 is connected to the source of Q101 through R100, and is also connected to the OTG_POWER_EN output terminal of the main control CPU and the POGO_IDDIG terminal of the POGO interface module. The first filter capacitor C103 is connected between the input terminal of U100 and ground, and the second filter capacitor C105 is connected between the output terminal of U100 and ground.

[0038] The overvoltage protection principle is: The overvoltage protection threshold voltage of the overvoltage protection chip U100 is set by external voltage divider resistors R101 and R103. Its setting principle is based on the resistor voltage divider formula: .

[0039] When the internal reference voltage of the chip is At that time, the overvoltage protection threshold is: .

[0040] in: The overvoltage protection threshold voltage is expressed in volts (V). The internal reference voltage of the overvoltage protection chip U100 is determined by the chip datasheet and is measured in volts (V). The resistance value of the first voltage divider resistor is expressed in ohms (Ω). The resistance value of the second voltage divider resistor is expressed in ohms (Ω).

[0041] In this invention, to match the PD 9V / 2A charging specification, the overvoltage protection threshold voltage is set to 10.5V. By selecting appropriate values ​​for R101 and R103, when the Type-C input voltage exceeds 10.5V, the internal comparator of U100 flips, controlling the internal power switch to turn off, cutting off the power supply path, and protecting the subsequent circuitry from damage due to excessive voltage.

[0042] The first PMOS transistor Q100 has a parasitic body diode. The positive terminal of the parasitic body diode is connected to the source of the first PMOS transistor Q100, and the negative terminal is connected to the drain of the first PMOS transistor Q100. When the first PMOS transistor Q100 is in the off state, the parasitic diode forms a unidirectional conductive path, allowing current to flow from the Type-C interface to the device's main power supply terminal VBUS, while blocking the reverse current path.

[0043] When the main control CPU outputs a high level at the OTG_POWER_EN signal terminal, the second PMOS transistor Q101 is turned on, which in turn drives the first PMOS transistor Q100 to be turned on, thus connecting the Type C power path. When the main control CPU outputs a low level at the OTG_POWER_EN signal terminal, the second PMOS transistor Q101 is turned off, the first PMOS transistor Q100 is turned off, and the Type C power path is turned off.

[0044] Q100 and Q101 constitute the core switching network for power path on / off control. The principle of power path on / off control is: (1) Default state: R100 biases the gate of Q101 to a high level (equal potential to the source), making Q101 in the off state. The gate of Q100 is at a high level through the path between the drain and source of Q101, and Q100 is also in the off state. At this time, the Type C power path is in the off state.

[0045] (2) USB device insertion detection: When a USB device (such as a charger, USB flash drive, etc.) is inserted into the Type-C interface, due to the parasitic diode D_Q100 inside Q100, its positive terminal (source) is connected to the Type-C power input terminal, and its negative terminal (drain) is connected to the device's main power terminal VBUS. When Q100 is not conducting, relying on the unidirectional conductivity of this parasitic diode, power can flow from the Type-C input terminal to the VBUS terminal, providing detection power to the main control CPU, enabling the main control CPU to detect the USB insertion signal.

[0046] The unidirectional conductivity characteristic of a parasitic diode can be expressed as: .

[0047] in: The forward current flowing through the diode is expressed in amperes (A). The reverse saturation current is expressed in amperes (A). This is the voltage across the diode, in volts (V). The ideal factor (usually between 1 and 2); Thermoelectric voltage, ,in Boltzmann constant ( ), Absolute temperature (unit: Kelvin, K). electron charge ( ), at room temperature .

[0048] This parasitic diode ensures that when Q100 is off, current can only flow from the Type C input to VBUS (forward), and cannot flow from VBUS to the Type C input in reverse (reverse cutoff), thus guaranteeing unidirectional safety of the power path under default conditions.

[0049] (3) Type-C power path is on: After the main control CPU detects the USB insertion signal, it outputs a high-level enable signal through the OTG_POWER_EN output terminal. This high-level signal is applied to the gate of Q101, causing the gate-source voltage of Q101 to... The conduction condition is met: .

[0050] in This is the turn-on threshold voltage (negative) of the PMOS transistor. When Less than At that time, Q101 is turned on.

[0051] When Q101 is turned on, its drain is pulled low, which in turn biases the gate of Q100, turning Q100 on. After Q100 is turned on, its drain-source resistance... With power reduced to the milliohm level, power can flow from the Type-C input to the VBUS input with a low-loss path, providing charging power to the main device.

[0052] (4) Path switching during charging on the charging dock: When the device is placed on the charging dock, the POGO_INT signal terminal of the POGO interface module is pulled low by the grounding contact inside the dock. The main control CPU detects this low-level signal and determines that the device has been placed on the dock. Subsequently, the main control CPU executes the following two control actions: Action 1: Pull the OTG_POWER_EN signal from high to low, thus reducing the gate-source voltage of Q101. As the voltage approaches zero, Q101 turns off, and consequently, the gate of Q100 loses its low-level bias, causing Q100 to turn off and the Type-C power path to be shut off.

[0053] Action 2: The POGO_IDDIG signal is also pulled low by the socket, directly affecting the gate of Q101, forcibly cutting off Q101 at the hardware level. Even if the OTG_POWER_EN signal of the main control CPU fails to be pulled low correctly due to an anomaly, Q101 cannot be turned on. This dual redundancy design (software control + hardware control) ensures the absolute reliability of the Type-C power path shutdown.

[0054] After the Type-C power path is turned off, the device charging power flows from the POGO_VBUS input terminal of the POGO interface module to the device main power terminal VBUS. At the same time, due to the reverse cutoff characteristic of the parasitic diode of Q100, the power cannot flow from VBUS to the Type-C output terminal in reverse, thus protecting the device connected to the Type-C port from being damaged by the 9V voltage of the base.

[0055] The POGO interface module 20 is the physical interface for connecting to the charging dock. It is responsible for receiving power and communication signals from the dock and providing dock insertion detection signals to the main control CPU. Figure 3 This is a circuit diagram of the POGO interface module 20 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 3 As shown, the POGO interface module 20 includes: POGO interface module 20 includes: POGO connector: includes POGO_VBUS power input contact, POGO_DP and POGO_DM differential data contacts, POGO_INT interrupt signal contact, POGO_IDDIG identification signal contact, and ground contact.

[0056] Common-mode inductor L200: Connected in series in the differential signal paths of POGO_DP and POGO_DM to suppress common-mode interference signals.

[0057] The first electrostatic discharge protection tube group, T200, T201, T202, and T203, are connected between each signal line and ground for electrostatic discharge protection.

[0058] Surge protection tube D200: Connects between the POGO_VBUS power line and ground for surge protection.

[0059] Filter capacitor C200: Connected in parallel between the POGO_VBUS power line and ground to filter out power ripple.

[0060] Self-resetting fuse resistor R202: Connected in series in the POGO_VBUS power path for overcurrent protection.

[0061] Signal resistor (not shown in the figure): connected between the POGO_DP and POGO_DM signal lines and ground, working with the electrostatic discharge tube to achieve ESD protection.

[0062] The POGO_VBUS terminal is connected to the power output contact of the base, and is also connected to the main power supply terminal VBUS of the device and one end of the filter capacitor C200. The other end of C200 is grounded; D200 is connected in parallel between POGO_VBUS and ground; R202 is connected in series in the POGO_VBUS path; The POGO_DP terminal is connected to the first input terminal of the common mode inductor L200, and the first output terminal of L200 is connected to the USB signal switching module 40. The POGO_DM terminal is connected to the second input terminal of the common mode inductor L200, and the second output terminal of L200 is connected to the USB signal switching module 40; T200 and T201 are connected between the POGO_DP signal line and ground, and between the POGO_DM signal line and ground, respectively; The POGO_INT pin is connected to the interrupt input pin of the main control CPU, and is also connected to the positive power supply through a pull-up resistor; The POGO_IDDIG terminal is connected to the gate of Q101 in the power path switching module 10; T202 is connected between the POGO_INT signal line and ground; T203 is connected between the POGO_IDDIG signal line and ground.

[0063] The working principle of POGO interface module 20 is as follows: When the device is placed in the charging dock, the contacts of the POGO connector establish an electrical connection with the corresponding POGO probes on the dock. Specifically: The 9V / 2A charging power provided by the POGO_VBUS contact receiver base is delivered to the main power supply terminal VBUS of the device after passing through R202 current limiting protection, C200 filtering, and D200 surge protection.

[0064] The POGO_INT contact is connected to the internal ground terminal of the base and is pulled low from a high level. The main control CPU detects this falling edge interrupt signal and determines that the device has been placed in the base.

[0065] The POGO_IDDIG contact is also pulled low, and this low-level signal is directly applied to the gate of Q101, making the gate-source voltage of Q101 0V, ensuring that Q101 is in the off state. This hardware control path is independent of the CPU's software control, forming a dual-redundancy foolproof protection mechanism.

[0066] The POGO_DP and POGO_DM contacts establish a USB data communication connection, and USB peripherals on the dock (such as USB hubs, card readers, etc.) interact with the device through this differential signal path.

[0067] The common-mode inductor L200 presents high impedance to the common-mode component of a differential signal and low impedance to the differential-mode component. Its common-mode rejection principle can be expressed as: .

[0068] in: Common-mode impedance, in ohms (Ω); Angular frequency, , in radians per second (rad / s); This is the common-mode inductance, expressed in Henry (H).

[0069] Common-mode inductors improve the quality and reliability of USB signal transmission by suppressing common-mode interference signals.

[0070] The TypeC interface module 30 is a standard TypeC physical interface used to connect external TypeC devices, supporting TypeC protocol communication, PD charging protocol, OTG function, and C-to-C data transmission function. Figure 4 This is a circuit diagram of the Type-C interface module 30 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 4 As shown, the Type-C interface module 30 includes: Type-C Socket: A standard USB Type-C socket containing VBUS power pins, CC1 and CC2 configuration channel pins, D+ and D- data pins, SBU1 and SBU2 sideband pins, and a ground pin.

[0071] The second electrostatic discharge protection tube group T300, T301, T302, and T303 are connected between each data signal line and ground for electrostatic discharge protection.

[0072] Surge protection diode D300: Connected between the VBUS pin of Type-C and ground for surge protection.

[0073] Filter capacitor C300: Connected in parallel between the VBUS pin of Type C and ground for power supply filtering.

[0074] Common-mode inductor L300: Connected in series in the D+ and D- data signal paths of Type-C to suppress common-mode interference.

[0075] The VBUS pin of the Type-C socket is connected to the input terminal of the overvoltage protection chip U100 in the power path switching module 10; The CC1 and CC2 pins of the Type-C socket are connected to the corresponding input terminals of the CC protocol identification module 50; The D+ and D- pins of the Type-C socket are connected to the input of the common-mode inductor L300, and the output of L300 is connected to the USB signal switching module 40. T300 is connected between the CC1 signal line and ground, and T301 is connected between the CC2 signal line and ground; T302 is connected between the D+ signal line and ground, and T303 is connected between the D- signal line and ground; D300 is connected between the VBUS pin and ground; C300 is connected between the VBUS pin and ground.

[0076] The working principle of TypeC interface module 30 is as follows: The Type-C interface module 30 is the physical channel through which the device connects and communicates with external Type-C devices (such as PD chargers, Type-C flash drives, Type-C to USB adapters, and other Type-C devices).

[0077] When a Type-C device is inserted, the CC1 and CC2 pins establish a configuration channel connection with the external device. The CC protocol identification module 50 identifies the type of inserted device by detecting the voltage and resistance network on the CC pins, including DFP (Downstream Facing Port), UFP (Upstream Facing Port), or DRP (Dual Role Port). Simultaneously, the CC protocol chip is also responsible for negotiating the PD charging protocol and determining the voltage and current transmission parameters.

[0078] The VBUS pin of the Type-C device is connected to the device's power system through the power path switching module 10. When Q100 in the power path switching module 10 is turned on, external Type-C power can flow into the device to charge it or power an inserted OTG device.

[0079] The T300-T303 electrostatic discharge (ESD) protection assembly discharges ESD energy to ground, protecting downstream circuitry. The ESD protection principle is based on the avalanche breakdown effect. .

[0080] When electrostatic voltage Exceeding the breakdown voltage of the protection tube At that time, the protective pipe quickly enters the avalanche breakdown state, releasing the high voltage energy to the ground, thereby limiting the clamping voltage to a safe range.

[0081] The USB signal switching module 40 is the core component for switching USB signal paths, responsible for switching the USB signal path between the Type-C interface and the POGO dock interface. Figure 5 This is a circuit diagram of the USB signal switching module 40 in the foolproof protection circuit for the Type-C charging port of the device with a charging dock according to the present invention. Figure 5 As shown, the USB signal switching module 40 includes: USB signal switching chip: It is a double-pole double-throw (DPDT) or dual-channel single-pole double-throw analog switch with two sets of differential signal channels, supporting the switching of high-speed USB signals (480Mbps).

[0082] Decoupling capacitor: Connected between the chip's power supply pin and ground to filter out power supply noise.

[0083] The first differential input terminal of the USB signal switching chip is connected to the D+ and D- signal lines of the Type-C interface module 30; The second differential input terminal of the USB signal switching chip is connected to the POGO_DP and POGO_DM signal lines of the POGO interface module 20; The common differential output terminal of the USB signal switching chip is connected to the USB signal input terminal of the main control CPU; The channel selection control terminal (SEL) of the USB signal switching chip is connected to the USB_SIGNAL_SW control signal terminal of the main control CPU. The power supply terminal (VCC) of the USB signal switching chip is connected to the output terminal of the power supply module 60; The decoupling capacitor is connected between the power supply terminal and ground.

[0084] The working principle of the USB signal switching module 40 is as follows: The USB signal switching chip routes the USB signal from the Type-C interface to the main control CPU by default. At this time, the SEL control terminal is in a high-level state or the default state.

[0085] When the main control CPU detects that the dock is inserted (POGO_INT is pulled low), the main control CPU outputs a low level at the USB_SIGNAL_SW control signal terminal. This low-level signal is applied to the SEL terminal of the USB signal switching chip, and the internal switch of the control chip switches the common output terminal from the first differential input terminal (Type C path) to the second differential input terminal (POGO path).

[0086] At this point, the USB peripherals on the dock (such as USB keyboards, USB card readers, USB printers, etc. extended through the dock) establish a data connection with the main control CPU, and users can interact with data through the peripherals on the dock, improving the ease of use of the device in dock scenarios.

[0087] On-resistance of USB signal switching switch and bandwidth It is a key parameter affecting signal quality. Signal attenuation can be expressed as: .

[0088] in: This represents the signal attenuation, expressed in decibels (dB). The load resistance is expressed in ohms (Ω). The on-resistance of the switch is expressed in ohms (Ω).

[0089] The USB signal switching switch selected in this embodiment has low on-resistance (typical value <5Ω) and high bandwidth (>500MHz), which can meet the transmission requirements of USB 2.0 high-speed signals.

[0090] The CC protocol identification module 50 is the core component for Type-C protocol identification, responsible for identifying the type of device connected to the Type-C interface and negotiating the PD charging protocol. For example... Figure 6As shown, the CC protocol identification module 50 includes: CC Protocol Chip: A dedicated chip that supports the USB Type-C standard protocol and the PD (Power Delivery) protocol. It integrates a CC logic detection circuit, a PD protocol engine, a BMC (Biphase Mark Coding) codec, and a communication interface.

[0091] Peripheral circuits include power supply decoupling capacitors, clock circuits, etc.

[0092] The CC1 terminal of the CC protocol chip is connected to the CC1 pin of the Type-C interface module 30; The CC2 terminal of the CC protocol chip is connected to the CC2 pin of the Type-C interface module 30; The communication interface (I2C or UART) of the CC protocol chip is connected to the corresponding communication port of the main control CPU. The power supply terminal (VDD) of the CC protocol chip is connected to the output terminal of the power supply module 60.

[0093] The working principle of the CC protocol identification module 50 is as follows: The CC protocol chip determines the device connection status and type on the Type-C interface by detecting the voltage on the CC1 and CC2 pins and the pull-up / pull-down resistor network.

[0094] In the Type-C protocol specification, the device type is indicated by the voltage on the CC pin. To identify: .

[0095] in: Voltage detected at the CC pin, in volts (V). This is the supply voltage, measured in volts (V). The pull-up and pull-down resistors at the device end are measured in ohms (Ω). The terminating resistance of the Type-C cable or the device at the other end, in ohms (Ω).

[0096] The CC protocol chip determines the device based on the detected voltage value: if Rd (5.1kΩ pull-down resistor) is detected, it indicates a UFP device; if Rp (pull-up resistor) is detected, it indicates a DFP device; if Ra (22kΩ pull-up resistor) is detected, it indicates a Type-C active cable is connected.

[0097] During the PD charging protocol negotiation process, the CC protocol chip and the peer device communicate via the CC pin using BMC encoding to negotiate voltage and current parameters. The negotiation process is based on the following power formula: .

[0098] in: Charging power, measured in watts (W). The negotiated bus voltage is in volts (V). The negotiated bus current is in amperes (A).

[0099] In this embodiment, the CC protocol chip supports negotiating the PD 9V / 2A charging specification, i.e., the maximum charging power is 18W. The CC protocol chip reports the negotiation results and connection status to the main control CPU through the communication interface, providing a basis for the CPU to make power path switching decisions.

[0100] The power supply module 60 is an auxiliary power supply unit responsible for providing operating power to the USB signal switching module 40 and the CC protocol identification module 50. Figure 7 This is a circuit diagram of the power supply module 60 in the foolproof protection circuit for the Type-C charging port of the device with charging dock of the present invention. Figure 7 As shown, the power supply module 60 includes: Low dropout linear regulator (LDO): Converts the main power supply VBUS of the equipment to a stable low voltage to power each module.

[0101] Filter capacitor: Connected between the input terminal and the output terminal and ground, used for power supply decoupling.

[0102] The input of the LDO is connected to the device's main power supply terminal VBUS; The output of the LDO is connected to the power supply of the USB signal switching module 40 and the power supply of the CC protocol identification module 50, respectively. The filter capacitor is connected between the LDO input terminal and ground, and between the output terminal and ground.

[0103] The working principle of power supply module 60 is as follows: The power supply module 60 converts the device's main power supply VBUS (typically 5V or 9V) to a low voltage (typically 3.3V), providing a stable operating power supply for the USB signal switching chip and the CC protocol chip. The LDO's voltage regulation principle is based on the following formula: .

[0104] in: The output voltage of the LDO is expressed in volts (V). This is the internal reference voltage of the LDO, in volts (V). and For feedback voltage divider resistors, the unit is ohms (Ω).

[0105] The following describes the working principle of the foolproof protection circuit for the Type-C charging port of the device with charging dock of this invention, combined with different usage scenarios: (1) Standby mode: When the device is in standby mode, no device is plugged into the Type-C port, and the device is not placed in the charging dock. At this time: In the power path switching module 10, both Q100 and Q101 are in the default off state, and the Type C power path is turned off. The main control CPU outputs a low level at the OTG_POWER_EN signal terminal; The POGO_INT signal is at a high level (pulled up by a pull-up resistor); By default, the USB signal switching module 40 routes the USB signal from the Type-C interface to the main control CPU; The entire circuit is in a low-power standby state.

[0106] (2) Type-C device insertion status: When a user inserts a Type-C device (such as a PD charger, Type-C USB flash drive, etc.) into the device's Type-C port: The VBUS pin of the TypeC interface module 30 provides a unidirectional current path to the main power supply terminal VBUS of the device through the parasitic diode inside Q100, and provides detection power to the main control CPU. The main control CPU detects an increase in VBUS voltage and determines that a Type-C device has been inserted. The CC protocol identification module 50 detects the device type and negotiates the charging protocol (such as PD 9V / 2A) through the CC1 / CC2 pins. The main control CPU outputs a high-level enable signal through the OTG_POWER_EN terminal; Q101 is turned on, which in turn turns on Q100, thus connecting the Type-C power path; An external power source supplies power to the device via a Type-C interface, or the device supplies power to an external OTG device via a Type-C interface. The USB signal switching module 40 maintains the Type-C path state, and the Type-C device establishes USB data communication with the main control CPU.

[0107] (3) Equipment placed in the base: When the user places the device in the charging dock: Each contact of the POGO interface module 20 establishes an electrical connection with the base probe; The POGO_INT signal was pulled low by the base, and the main control CPU detected a falling edge interrupt signal; The POGO_IDDIG signal was also pulled low, and the hardware directly shut down Q101; The main control CPU pulls the OTG_POWER_EN signal low, and Q101 is shut down by software. The dual protection mechanism ensures that Q101 is reliably shut down, and Q100 is subsequently shut down, thus completely cutting off the Type-C power path. The 9V power supply from the base flows into the device through the POGO_VBUS terminal, and after passing through R202, D200, and C200, it is delivered to VBUS to charge the device. The parasitic diode of Q100 is reverse-biased to prevent the VBUS voltage from being output to the Type-C interface in reverse. The main control CPU controls the USB signal switching module 40 through the USB_SIGNAL_SW terminal to switch the USB signal path from the Type C path to the POGO path. The USB peripherals on the base establish a data connection with the main control CPU.

[0108] In the above process, the switching relationship between the Type-C power path and the POGO power path can be expressed as: .

[0109] This switching logic ensures that the Type-C power path is completely shut off when the dock is charging, avoiding the risk of the 9V voltage from the dock damaging Type-C external devices.

[0110] (4) Equipment detached from base: When the user removes the device from the charging dock: POGO interface module 20 is electrically disconnected from the base probe; When the POGO_INT signal returns to a high level, the main control CPU detects the rising edge state change. The POGO_IDDIG signal returns to a high level, releasing the hardware shutdown of Q101; The main control CPU controls the USB_SIGNAL_SW terminal to return to a high level, and the USB signal switching module 40 restores the USB signal path to the Type C path. The main control CPU keeps the OTG_POWER_EN signal low, waiting for the next Type-C device to be inserted.

[0111] Example 2 In this embodiment, the foolproof protection circuit of the present invention is integrated into the main board of the POS terminal and applied to the POS terminal device. The POS terminal is also equipped with a Type-C interface (located at the bottom or side of the device) and POGO charging contacts (located on the back of the device).

[0112] Use case 1: Type-C charging.

[0113] Users connect a Type-C charger that supports the PD protocol to the Type-C interface of the POS terminal. The overvoltage protection chip U100 detects the input voltage; when the input voltage is within the normal range (5V or 9V), U100 conducts. The main control CPU detects the insertion of the PD charger through the CC protocol chip, outputting a high level OTG_POWER_EN, driving Q100 and Q101 to conduct, connecting the Type-C power path, and charging the POS terminal. At this time, the charging power can reach 18W (9V / 2A), meeting the fast charging requirements of the POS terminal.

[0114] Use case 2: Type-C data transmission.

[0115] Users connect the POS terminal to their computer using a Type-C data cable. The main control CPU detects the insertion of the DFP device (computer) via the CC protocol chip and controls the power path to be turned on. At the same time, the USB signal switching module 40 maintains the Type-C path, establishing a USB data connection between the POS terminal and the computer, allowing users to manage POS terminal files via the computer.

[0116] Use case 3: Base charging and foolproof protection.

[0117] The user places the POS terminal into the charging dock. The POGO_INT signal is pulled low. Upon detecting this signal, the main control CPU pulls the OTG_POWER_EN signal low, and simultaneously hardware-shuts down Q101 for the POGO_IDDIG signal. The Type-C power path is doubly shut down. The dock provides 9V / 2A charging power to the POS terminal via POGO_VBUS. At this time, even if a Type-C USB flash drive is still plugged into the Type-C interface, the flash drive will not be damaged by the 9V voltage because the Type-C VBUS pin has been completely disconnected internally by Q100 and U100, and the parasitic diode of Q100 is reverse-biased.

[0118] At the same time, the USB_SIGNAL_SW signal controls the USB signal switching module 40 to switch the USB signal path to the POGO path, and the USB keyboard or USB card reader on the base establishes a connection with the POS terminal, making it convenient for cashiers to operate.

[0119] Implementation Three In this embodiment, the foolproof protection circuit of the present invention is applied to an industrial-grade handheld data terminal. This data terminal is used in scenarios such as warehouse management and logistics distribution, where the device needs to be frequently accessed and placed on a charging dock.

[0120] System parameter settings: In this embodiment, the overvoltage protection threshold of the overvoltage protection chip U100 is set to 10.5V. The selection of voltage divider resistors R101 and R103 must meet the following requirements: .

[0121] Assuming the internal reference voltage of U100 ,but: ; .

[0122] If R103 = 10kΩ is selected, then R101 = 77.5kΩ, and a standard resistance value of 75kΩ can be selected for calibration.

[0123] By properly configuring the voltage divider resistors, the overvoltage protection threshold is ensured to be accurately 10.5V. When the Type-C input voltage abnormally rises above 10.5V, the U100 immediately cuts off the power path to protect the downstream circuitry.

[0124] Verification of foolproof protection effectiveness: When the handheld data terminal was placed in the charging dock, the voltage of the VBUS pin of the Type-C interface to ground was measured with a multimeter. The measured value was approximately 0V (the actual measured value may be in the millivolt range due to leakage current). This indicates that the Type-C power path was completely cut off. Simultaneously, the Type-C VBUS voltage waveform was monitored with an oscilloscope at the moment the dock was inserted. No voltage spikes or transient pulses were observed, proving that the power path switching process was smooth and reliable.

[0125] Anti-interference performance: In industrial environments, the POGO_INT signal line of the POGO interface is susceptible to electromagnetic interference, which can cause false triggering. This invention employs a dual hardware and software confirmation mechanism for anti-interference design: when POGO_INT is pulled low, the main control CPU will sample it three times consecutively (with a sampling interval of 10ms). Only after the confirmation signal remains low for more than 20ms will it be considered a valid dock insertion, effectively avoiding false triggering caused by electromagnetic interference.

[0126] Example 4 This embodiment provides a foolproof protection method for the Type-C charging port's foolproof protection circuit using the above-mentioned charging device with a charging dock, including the following steps: Step S1: When the device is in standby mode, the Type C power path and POGO power path of the power path switching module 10 are both in the default off state, and the parasitic diode of the Type C interface module 30 forms a unidirectional conductive path, enabling the Type C interface to send a USB insertion detection signal to the main control CPU. Step S2: When a Type-C device is inserted, the main control CPU detects the USB insertion signal and outputs an OTG_POWER_EN high-level enable signal to the power path switching module 10, driving the first PMOS transistor Q100 and the second PMOS transistor Q101 to conduct, connecting the Type-C power path, so that power flows from the Type-C interface to the device's main power terminal VBUS. Step S3: When the device is placed in the charging dock, the POGO_INT signal terminal of the POGO interface module 20 is pulled low by the dock. The main control CPU detects this low-level signal and determines that the device has been placed in the dock. Step S4: The main control CPU pulls the OTG_POWER_EN signal from high level to low level, which turns off the first PMOS transistor Q100 and the second PMOS transistor Q101, shutting down the Type C power path. At the same time, the POGO_IDDIG signal is pulled low, and the hardware forces the second PMOS transistor Q101 to shut down, forming a dual protection of hardware and software. Step S5: Power flows from the POGO_VBUS input terminal of the POGO interface module 20 to the main power terminal VBUS of the device to charge the device. At the same time, the Type C power path is cut off to prevent the 9V voltage of the base from being output to the external device in reverse through the Type C interface. Step S6: The main control CPU controls the USB signal switching module 40 through the USB_SIGNAL_SW control signal terminal to switch the USB signal path from the Type C path to the POGO path, so that the dock's USB peripheral can be connected to the device. Step S7: When the device leaves the base, the POGO_INT signal returns to a high level. The main control CPU detects this state change, controls the USB signal switching module 40 to restore the USB signal path to the Type C path, and waits for the Type C device to be inserted to reconnect the Type C power path.

[0127] The foolproof protection circuit and method for the Type-C charging port of the device with dock charging provided by this invention can be widely used in various electronic devices that require both a Type-C interface and dock charging, including but not limited to: POS terminal equipment and payment terminal equipment; Handheld data collection terminals and barcode scanning devices; Tablet computers and portable computers; Medical monitoring equipment and handheld testing instruments; Industrial control terminals and human-machine interaction devices.

[0128] The circuit structure of this invention is simple, and the components are widely available, making it suitable for mass production and demonstrating good industrial applicability. Furthermore, the method flow of this invention can be implemented through software programming, facilitating functional upgrades and deployment on existing hardware platforms.

[0129] The beneficial effects of the present invention, through the design of the above embodiments, are as follows: (1) Automatic error prevention and high safety: The PMOS switching network of the power path switching module 10, together with the software control of the main control CPU and the hardware control of POGO_IDDIG, realizes a dual redundant shutdown mechanism for the Type C power path. When the device is placed in the dock, even if the control signal of the main control CPU is abnormal due to software failure, the hardware control signal of POGO_IDDIG can still independently shut down the power path, ensuring that there is absolutely no voltage output from the Type C interface, fundamentally avoiding the risk of the 9V voltage of the dock burning out the Type C external device.

[0130] (2) No need to modify the product appearance, maintaining aesthetics: In the prior art, the error prevention function is mostly achieved through mechanical error prevention structure, which requires changes to the product appearance and increases design complexity. The present invention achieves error prevention protection through pure circuit design, without any changes to the overall appearance of the machine, and the original appearance and aesthetics of the product are completely preserved. Moreover, the relevant circuit structure is hidden inside the device, with good concealment and does not affect the user experience.

[0131] (3) Supports full-function standard Type-C with good compatibility: The Type-C interface module 30 supports the standard Type-C protocol and PD charging protocol. Users can use a standard Type-C port charger to charge the device, insert it into a computer to transfer data, and use a Type-C USB flash drive. The CC protocol identification module 50 supports the identification of various device types such as OTG devices, PD charging devices, and C-to-C data devices, and has good compatibility.

[0132] (4) Automatic dual-path switching for ease of use: Automatic identification and switching between the Type-C charging path and the dock charging path are realized. After the user places the device on the dock, the charging path automatically switches to the dock, and the USB signal path automatically switches to the dock peripheral, without the need for manual operation by the user, thus improving the ease of use.

[0133] (5) Simple circuit structure and controllable cost: By using discrete components, there is no need to customize dedicated chips. The components are widely available and the cost is controllable. At the same time, the circuit structure is relatively simple and easy to integrate into the motherboard of existing equipment, with good manufacturability and scalability.

[0134] This invention has been described with reference to specific embodiments, but those skilled in the art will understand that various changes and equivalent substitutions can be made without departing from the scope of the invention. Furthermore, numerous modifications can be made to this invention to suit specific applications without departing from its protection scope. Therefore, this invention is not limited to the specific embodiments disclosed herein, but includes all embodiments falling within the scope of the claims.

Claims

1. A foolproof protection circuit for the Type-C charging port of a device with a charging dock, characterized in that, include: The TypeC interface module (30) is used to connect to external TypeC devices and supports TypeC protocol communication and PD charging protocol. The POGO interface module (20) is used to connect to the charging dock and receive power signals and communication signals input from the dock; The power path switching module (10) is electrically connected to the TypeC interface module (30) and the POGO interface module (20) respectively, and is used to control the switching of the charging power path between the TypeC path and the POGO path; The USB signal switching module (40) is electrically connected to the TypeC interface module (30), the POGO interface module (20) and the main control CPU respectively, and is used to control the USB signal path to switch between the TypeC path and the POGO path; The CC protocol identification module (50) is electrically connected to the Type C interface module (30) and is used to identify the type of device inserted into the Type C interface and the PD charging protocol. The power supply module (60) is electrically connected to the USB signal switching module (40) and the CC protocol identification module (50) respectively, and is used to provide working power to the USB signal switching module (40) and the CC protocol identification module (50); The main control CPU is electrically connected to the power path switching module (10), the USB signal switching module (40) and the POGO interface module (20) respectively. According to the dock insertion detection signal of the POGO interface module (20), the CPU controls the power path switching module (10) and the USB signal switching module (40) to perform path switching.

2. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 1, characterized in that, The power path switching module (10) includes: The overvoltage protection chip U100 has its input terminal connected to the VBUS pin of the Type-C interface to monitor the Type-C power input voltage. When the input voltage exceeds the preset protection threshold, the power path is cut off. The first PMOS transistor Q100 and the second PMOS transistor Q101 are connected. The source of the first PMOS transistor Q100 is connected to the output terminal of the overvoltage protection chip U100, the drain is connected to the main power supply terminal VBUS of the device, and the gate is connected to the drain of the second PMOS transistor Q101. The source of the second PMOS transistor Q101 is connected to the output terminal of the overvoltage protection chip U100, and the gate is connected to the OTG_POWER_EN control signal terminal of the main control CPU and the POGO_IDDIG signal terminal of the POGO interface module (20), respectively. The first bias resistor R100 is connected between the gate and source of the second PMOS transistor Q101 to provide the gate bias voltage. The first voltage divider resistor R101 and the second voltage divider resistor R103 are connected in series between the voltage setting terminal of the overvoltage protection chip U100 and ground, and are used to set the overvoltage protection threshold voltage.

3. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 2, characterized in that, The overvoltage protection threshold voltage of the overvoltage protection chip U100 is set by the following formula: ; in, This is the overvoltage protection threshold voltage. This is the internal reference voltage of the overvoltage protection chip U100. The resistance value of the first voltage divider resistor is... The resistance value of the second voltage divider resistor; The resistance values ​​of the first voltage divider resistor R101 and the second voltage divider resistor R103 are configured such that the overvoltage protection threshold voltage is 10.5V to match the PD 9V / 2A charging specification.

4. The foolproof protection circuit for the Type-C charging port of the device with charging dock according to claim 2, characterized in that, The first PMOS transistor Q100 has a parasitic body diode, the positive terminal of which is connected to the source of the first PMOS transistor Q100, and the negative terminal is connected to the drain of the first PMOS transistor Q100. When the first PMOS transistor Q100 is in the off state, the parasitic diode forms a unidirectional conductive path, allowing current to flow from the Type-C interface to the device's main power supply terminal VBUS, while blocking the reverse current path.

5. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 2, characterized in that, When the main control CPU outputs a high level at the OTG_POWER_EN signal terminal, the second PMOS transistor Q101 is turned on, which in turn drives the first PMOS transistor Q100 to be turned on, thus connecting the Type C power path. When the OTG_POWER_EN signal terminal of the main control CPU outputs a low level, the second PMOS transistor Q101 is turned off, the first PMOS transistor Q100 is turned off, and the Type C power path is turned off.

6. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 1, characterized in that, The POGO interface module (20) includes: The POGO power input terminal POGO_VBUS is used to connect to the base power output; The POGO interrupt signal terminal POGO_INT is connected to the interrupt input terminal of the main control CPU and is used to send a low-level insertion detection signal to the main control CPU when the device is placed in the base. The POGO identification signal terminal POGO_IDDIG is connected to the power path switching module (10) and is used to hardware turn off the power path switching module (10) by a low-level signal when the device is placed in the base. The common-mode inductor L200 is connected in the POGO data signal path to suppress common-mode interference; The first electrostatic discharge protection tube group T200, T201, T202, and T203 are respectively connected between the POGO data signal line and ground for electrostatic discharge protection; The surge protection tube D200 is connected between the POGO power input terminal and ground for surge protection. The filter capacitor C200 is connected in parallel between the POGO power input terminal and ground for power filtering. The self-resetting fuse resistor R202 is connected in series with the POGO power input terminal for overcurrent protection.

7. The foolproof protection circuit for the Type-C charging port of the device with charging dock according to claim 1, characterized in that, The USB signal switching module (40) includes a USB signal switching chip, whose first signal path is connected to the USB signal terminal of the Type-C interface module (30), the second signal path is connected to the USB signal terminal of the POGO interface module (20), and the common signal terminal is connected to the USB signal terminal of the main control CPU. The channel selection control terminal of the USB signal switching chip is connected to the USB_SIGNAL_SW control signal terminal of the main control CPU. When the main control CPU detects that the dock is inserted, the USB_SIGNAL_SW control signal terminal outputs a low level, controlling the USB signal switching chip to switch the USB signal path from the Type C path to the POGO path.

8. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 1, characterized in that, The TypeC interface module (30) includes: The Type-C socket has its VBUS pin connected to the power path switching module (10), its CC1 and CC2 pins connected to the CC protocol identification module (50), and its D+ and D- pins connected to the USB signal switching module (40). The second electrostatic discharge protection tube group T300, T301, T302, and T303 are connected between the Type-C data signal line and ground, respectively, for electrostatic discharge protection. The surge protector D300 is connected between the VBUS pin of the Type-C connector and ground for surge protection. The filter capacitor C300 is connected in parallel between the VBUS pin of the Type-C circuit and ground for power supply filtering. The common-mode inductor L300 is connected in series in the Type-C data signal path to suppress common-mode interference.

9. The foolproof protection circuit for the Type-C charging port of the device with a charging dock according to claim 1, characterized in that, The CC protocol identification module (50) includes a CC protocol chip, and the CC1 and CC2 terminals of the CC protocol chip are respectively connected to the CC1 and CC2 pins of the Type C interface module (30); The CC protocol chip is used to identify the type of device connected to the Type-C interface, including OTG devices, PD charging devices and C-to-C data devices, and transmits the identification result to the main control CPU through the communication interface.

10. A foolproof protection method for a Type-C charging port of a device using a charging dock as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: When the device is in standby mode, the Type C power path and POGO power path of the power path switching module (10) are both in the default off state. The parasitic diode of the Type C interface module (30) forms a unidirectional conductive path, enabling the Type C interface to send a USB insertion detection signal to the main control CPU. Step S2: When the Type C device is inserted, the main control CPU detects the USB insertion signal and outputs the OTG_POWER_EN high-level enable signal to the power path switching module (10), driving the first PMOS transistor Q100 and the second PMOS transistor Q101 to turn on, connecting the Type C power path, so that the power flows from the Type C interface to the device's main power terminal VBUS. Step S3: When the device is placed in the charging dock, the POGO_INT signal terminal of the POGO interface module (20) is pulled low by the dock. The main control CPU detects the low-level signal and determines that the device has been placed in the dock. Step S4: The main control CPU pulls the OTG_POWER_EN signal from high level to low level, which turns off the first PMOS transistor Q100 and the second PMOS transistor Q101, shutting down the Type C power path. At the same time, the POGO_IDDIG signal is pulled low, and the hardware forces the second PMOS transistor Q101 to shut down, forming a dual protection of hardware and software. Step S5: Power flows from the POGO_VBUS input terminal of the POGO interface module (20) to the main power terminal VBUS of the device to charge the device. At the same time, the Type C power path is cut off to prevent the 9V voltage of the base from being output to the external device in reverse through the Type C interface. Step S6: The main control CPU controls the USB signal switching module (40) through the USB_SIGNAL_SW control signal terminal to switch the USB signal path from the Type C path to the POGO path, so that the dock USB peripheral can be connected to the device; Step S7: When the device leaves the base, the POGO_INT signal returns to a high level. The main control CPU detects this state change, controls the USB signal switching module (40) to restore the USB signal path to the Type C path, and waits for the Type C device to be inserted to reconnect the Type C power path.

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