Mini PCIe interface-based domestic and foreign 4G and 5G module compatible circuit

Abstract

The application discloses a domestic and foreign 4G and 5G module compatible circuit based on a Mini PCIe interface, which comprises a power supply voltage switching circuit, a DCDC enable control circuit, a USB communication selection circuit, an I2S audio communication selection circuit and a Mini PCIe interface connection end. The power supply switching circuit adopts a NPN triode and a resistor to form a DCDC feedback circuit, 3.3V / 3.8V voltage switching is realized through GPIO control, and the power supply demand of domestic and foreign modules is adapted; the enable control circuit controls the start and stop of the DCDC through GPIO, and solves the abnormal problem of the module after voltage misconnection; the USB communication selection circuit realizes USB2.0 / 3.2 protocol switching through element selection. The application realizes low-cost compatibility with discrete devices, does not need high-priced chips, has voltage intelligent switching, communication flexible adaptation and abnormal recovery functions, improves product applicability and reliability, and reduces production and use costs.

Description

Technical Field

[0001] This invention relates to the field of 4G and 5G module compatible circuit technology based on Mini PCIe interface, and in particular to a domestic and foreign 4G and 5G module compatible circuit based on Mini PCIe interface. Background Technology

[0002] As an industry-standardized physical connection interface, the Mini PCIe interface provides a convenient basis for the insertion, removal, and interchangeability of 4G / 5G communication modules, and has been widely used in various smart terminals, industrial control equipment, and communication terminal products. However, despite the unified interface definition, there is a key difference in power supply between domestic and international Mini PCIe 4G / 5G modules: domestic versions generally use a 3.8V power supply standard, while international versions uniformly use a 3.3V power supply standard. This core difference means that existing products often only support a single version of the module, failing to achieve compatibility between domestic and international modules. Furthermore, designs that simultaneously support both 4G and 5G modules are extremely rare in the current market, further limiting the product's adaptability and application scope.

[0003] The aforementioned compatibility issues have caused numerous problems for manufacturing, product promotion, and user operation: For manufacturers, it necessitates developing product models with differentiated power supply circuits for different regions, increasing R&D costs and material management complexity; for users, mistakenly connecting a 3.8V domestic module to a 3.3V power supply circuit, or vice versa, can not only prevent the module from starting but may also cause hardware burnout, posing a high risk of failure. Furthermore, with the widespread adoption of 5G technology, some 5G modules already support the USB 3.2 high-speed communication protocol, while traditional 4G modules and entry-level 5G modules still only support the USB 2.0 protocol. Moreover, 4G modules vary in their support for I2S audio, and existing circuits are mostly designed for a single communication protocol, further exacerbating the difficulty of adapting 4G and 5G modules for mixed use.

[0004] To address the aforementioned issues, existing solutions often have significant limitations: some solutions design dedicated power supply circuits for single-version modules, resulting in products that can only be adapted to specific domestic or foreign modules, exhibiting extremely poor versatility; while a few compatibility solutions attempt to solve the voltage compatibility problem, they often ignore the differences in communication protocols between 4G and 5G modules, and their implementation is complex and costly. Therefore, developing a circuit solution that can simultaneously solve power supply voltage switching, communication protocol adaptation, and 4G / 5G module compatibility has become a key requirement for overcoming current technological bottlenecks. Summary of the Invention

[0005] The purpose of this invention is to provide a domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A circuit compatible with domestic and international 4G and 5G modules based on a Mini PCIe interface, comprising a power supply voltage switching circuit, a DC-DC enable control circuit, a Mini PCIe interface connection terminal, a DC-DC chip, an inductor, and a filter capacitor bank; the power supply voltage switching circuit is connected to the feedback pin of the DC-DC chip and is used to output a power supply voltage adapted to domestic and international 4G / 5G modules to the Mini PCIe interface connection terminal; the DC-DC enable control circuit is connected to the enable pin of the DC-DC chip and is used to control the voltage output state of the DC-DC chip; the Mini PCIe interface connection terminal is used to interface with domestic and international 4G / 5G modules.

[0007] Preferably, the power supply voltage switching circuit includes a first NPN transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; the feedback pin of the DC-DC chip is connected to one end of the first resistor and one end of the second resistor, respectively, and the other end of the second resistor is grounded; the other end of the first resistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the collector of the first NPN transistor; the base of the first NPN transistor is connected to the first GPIO control terminal through the fourth resistor, and the base is also connected to one end of the fifth resistor, which is a pull-down resistor, and its other end is grounded; the emitter of the first NPN transistor is directly grounded.

[0008] Preferably, when the first GPIO control terminal outputs a low level, the first NPN transistor is turned off, and the second resistor forms a voltage divider network with the first resistor alone, so that the DC-DC chip outputs a power supply voltage compatible with foreign 4G / 5G modules; when the first GPIO control terminal outputs a high level, the first NPN transistor is turned on, and the second resistor and the third resistor are connected in parallel and then form a voltage divider network with the first resistor, so that the DC-DC chip outputs a power supply voltage compatible with domestic 4G / 5G modules.

[0009] Preferably, the DC-DC enable control circuit includes a second NPN transistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor; the enable pin of the DC-DC chip is connected to the collector of the second NPN transistor, one end of the sixth resistor, and one end of the eighth resistor, respectively, and the other end of the eighth resistor is connected to the power supply; the base of the second NPN transistor is connected to the second GPIO control terminal through the seventh resistor, and the base is also connected to one end of the ninth resistor, and the other end of the ninth resistor is connected to the power supply.

[0010] Preferably, the enable pin of the DC-DC chip has a lower voltage threshold and an upper voltage threshold; when the voltage of the enable pin is less than the lower voltage threshold, the DC-DC chip stops outputting voltage; when the voltage of the enable pin is greater than the upper voltage threshold, the DC-DC chip starts outputting voltage; and by controlling the enable of the DC-DC through the second GPIO control terminal, the DC-DC power supply can be restarted to adapt to different version modules.

[0011] Preferably, the DC-DC chip is a wide voltage regulation DC-DC converter chip, with its power input pin connected to a first power supply voltage and a second power supply voltage, the switch output pin connected to the output terminal through an inductor, the output terminal connected in parallel with a first filter capacitor bank, and the power input pin output terminal also connected in parallel with a second filter capacitor bank.

[0012] Preferably, it also includes a USB communication selection circuit, which is connected to the USB communication pin of the Mini PCIe interface connection terminal and is used to switch between USB 2.0 and USB 3.2 bus communication modes. Preferably, the USB communication selection circuit includes a first capacitor, a second capacitor, a tenth resistor, an eleventh resistor, and a twelfth resistor; the USB differential signal receiving pin of the Mini PCIe interface connection is connected to one end of the eleventh resistor, and the USB differential signal transmitting pin is connected to one end of the tenth resistor; the other end of the eleventh resistor is connected to the PERn0 pin, and the other end of the tenth resistor is connected to the PERp0 pin; one end of the twelfth resistor is connected to the RESET INn pin, and the other end is connected to the PETp0 pin; the USB differential signal receiving pin of the Mini PCIe interface connection is connected to one end of the first capacitor, and the USB differential signal transmitting pin is connected to one end of the second capacitor; the other end of the first capacitor is connected to the PETn0 pin, and the other end of the second capacitor is connected to the PETp0 pin.

[0013] Preferably, it also includes an I2S bus audio communication selection circuit, which includes four selectable resistors. One end of each selectable resistor is connected to one of the four reserved pins of the onboard CPU chip, and the other end is connected to the onboard CPU. By selecting whether the preset selectable resistors are installed or not, the audio communication function between the 4G module and the I2S bus can be enabled or disabled.

[0014] Beneficial effects: This invention addresses the power supply differences between domestic and international modules (3.3V / 3.8V) through a power supply voltage switching function, adapts to the USB 2.0 / 3.2 protocol differences between 4G / 5G modules through a USB communication selection function, and meets differentiated audio requirements through an I2S bus audio communication selection function. These three functions work collaboratively on a unified Mini PCIe interface, enabling the circuit to adapt to various combinations of scenarios, such as domestic 4G, USB 2.0, no audio, audio, and domestic / international 5G with USB 3.2, including combinations like (domestic 4G, no audio, USB 2.0) and (international 4G, no audio, USB 2.0). The compatibility has expanded from 2-3 scenarios with a single function to full-scenario adaptation covering multiple fields such as consumer electronics and industrial control, completely breaking through the technical bottleneck of existing circuits' single-dimensional adaptability.

[0015] All functional circuits in this invention employ discrete component designs using resistors, capacitors, and NPN transistors, coupled with a wide-voltage adjustable general-purpose DC-DC chip, eliminating the need for expensive integrated chips. This modular design eliminates the need to develop multiple differentiated circuits for different combinations of power supply standards, communication protocols, and audio requirements; a single PCB board is sufficient, allowing for flexible adaptation to all scenarios through component selection and software configuration. Compared to traditional multi-version circuit solutions, this significantly reduces R&D costs and the number of material types, resulting in a substantial increase in yield during mass production and achieving a cost-optimal solution that covers all needs with a single solution.

[0016] All functional circuits in this invention are associated with the Mini PCIe interface. Products do not require redesigning circuits due to 4G to 5G module upgrades, regional adjustments for domestic re-export, or changes in audio functions. Adaptation can be achieved simply by switching GPIO levels or selecting components via software, significantly shortening the iteration cycle. The DC-DC enable control circuit can restart the power supply. Combined with the voltage divider network design of the power supply voltage switching circuit, a collaborative protection mechanism is formed where communication / audio functions are not activated when the power supply is not adapted, and are subsequently restored via a restart, greatly reducing the risk of module damage. Simultaneously, the unified hardware architecture allows troubleshooting to be based on the same set of circuit logic, improving maintenance efficiency by 50% and significantly outperforming single-function adaptation solutions in terms of reliability. Attached Figure Description

[0017] Figure 1 The schematic diagram of the power supply voltage switching circuit and the DC-DC enable control circuit provided for this invention; Figure 2 The schematic diagrams of the USB communication selection circuit and the I2S bus audio communication selection circuit provided by the present invention. Detailed Implementation

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] like Figures 1 to 2 As shown, the domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface disclosed in this invention includes a power supply voltage switching circuit, a DC-DC enable control circuit, a USB communication selection circuit, a Mini PCIe interface connection terminal (CON6), a first NPN transistor (Q21), a second NPN transistor (Q19), a DC-DC chip (U37), a first resistor (R312), a second resistor (R315), a third resistor (R231), a fourth resistor (R187), a fifth resistor (R214), a sixth resistor (R316), a seventh resistor (R318), an eighth resistor (R416), a ninth resistor (R425), a tenth resistor (R175), an eleventh resistor (R176), a twelfth resistor (R305), a first capacitor (C562), a second capacitor (C563), an inductor (L23), a first filter capacitor group (C459, C460, C461), and a second filter capacitor group (C456, C457, C458).

[0020] The DC-DC chip U37, model ETA8145FT2G, has its switch output pin (SW) connected to the output terminal (VDDADJ4G) via inductor L23. The output terminal is connected in parallel with the first filter capacitor group (C459, C460, C461). The power input pin (VIN) of U37 is connected to a second power supply voltage (VDD-8V5-MAIN) via a first supply voltage (VDD-3V3-MAIN). The second supply voltage (VDD-8V5-MAIN) is input... A second filter capacitor bank (C456, C457, C458) is connected in parallel at the output end; the inductor L23 is 3.3uH and rated current not less than 4A, used to realize the current freewheeling function; in the filter capacitor bank, C459 and C460 are both 22uF and the voltage rating is not less than 10V, C457 is 1uF and the voltage rating is not less than 25V, C456 is 22uF and the voltage rating is not less than 25V, and C461 and C458 are both 100nF and the voltage rating is not less than 25V, used to filter out the output voltage ripple.

[0021] The power supply voltage switching circuit is connected to the feedback pin (FB) of the DC-DC chip U37 to output a power supply voltage compatible with domestic and international 4G / 5G modules to the Mini PCIe interface connection terminal (CON6). Figure 1In this circuit, the first NPN transistor (Q21, model MMBT3904) and five resistors (R187, R214, R231, R312, R315) are used to form the external feedback circuit of the DC-DC converter. The first NPN transistor (Q21) is turned off or on by software program through one GPIO (1E7 / GPIO3_D7_d) to control the voltage output of the DC-DC converter to 3.3V or 3.8V, thereby enabling the power supply voltage of the 4G / 5G module to be switched to 3.3V or 3.8V. The specific connection is as follows: the feedback pin (FB) of the DC-DC chip U37 is connected to one end of the first resistor (R312) and one end of the second resistor (R315), respectively, and the other end of the second resistor (R315) is grounded; the other end of the first resistor (R312) is connected to one end of the third resistor (R231), the other end of the third resistor (R231) is marked as DNP (not mounted), and is connected to the collector of the first NPN transistor (Q21); the base of the first NPN transistor (Q21) is connected through... The fourth resistor (R187) is connected to the first GPIO control terminal (1E7 / GPIO3_D7_d), and its base is also connected to one end of the fifth resistor (R214). The fifth resistor (R214) is a pull-down resistor, and its other end is grounded. The emitter of the first NPN transistor (Q21) is directly grounded. One end of the auxiliary capacitor C455 (15pF / 50V) is connected to the feedback pin (FB) of U37, and the other end is connected to the output terminal (VDDADJ4G) to filter out high-frequency noise from the input power supply. Its working mechanism is as follows: (1) When the software program controls the GPIO (1E7 / GPIO3_D7_d) signal to be low (the hardware default pull-down resistor is 10K (the fifth resistor R214), which is low), the first NPN transistor (Q21) is in the off state, and the voltage divider resistance of the FB external feedback circuit is 10.5KΩ of the second resistor R315. By forming a voltage divider feedback with the first resistor R312 (34.8KΩ), the DC-DC output voltage is 3.3V, thereby realizing the 3.3V power supply to the foreign version 4G / 5G module; (2) When the software program controls the GPIO (1E7 / GPIO3_D7_d) signal to be high, The first NPN transistor (Q21) is in the conducting state. The voltage divider resistor value of the FB external feedback circuit is 8.814KΩ after R315 (10.5KΩ) and R231 (54.9KΩ) are connected in parallel. It forms a voltage divider feedback to the DC-DC through the first resistor R312 (34.8KΩ), thereby realizing the DC-DC output voltage of 3.8V, and thus realizing the 3.8V power supply to the domestic version of 4G / 5G module. Among them, the first resistor (R312) has a resistance of 34.8KΩ, the second resistor (R315) has a resistance of 10.5KΩ, the third resistor (R231) has a resistance of 54.9KΩ, the fourth resistor (R187) has a resistance of 1KΩ, and the fifth resistor (R214) has a resistance of 10KΩ.This solution uses GPIO software to control the on / off state of the NPN transistor, enabling intelligent switching between 3.3V and 3.8V DC-DC output voltages. It perfectly matches Mini PCIe 4G / 5G modules with different power supply standards at home and abroad, solving the communication compatibility problem between 4G and 5G modules. It truly achieves "one circuit compatible with multiple types of modules", greatly improving the product's applicable scenarios and market coverage.

[0022] The DC-DC enable control circuit is connected to the enable pin (EN) of the DC-DC chip U37 to control the voltage output state of the DC-DC chip U37. This circuit uses a GPIO (1D23 / GPIO1_B3_u) to control the turn-on or turn-off of the second NPN transistor (Q19) via software, thus controlling the voltage output of the DC-DC chip. Specifically, the connection is as follows: the enable pin (EN, pin 5) of the DC-DC chip U37 is connected to the collector of the second NPN transistor (Q19), one end of the sixth resistor (R316), and one end of the eighth resistor (R416), with the other end of the eighth resistor (R416) connected to the power supply; the base of the second NPN transistor (Q19) is connected to the second GPIO control terminal (1D23 / GPIO1_B3_u) through the seventh resistor (R318), and the base is also connected to one end of the ninth resistor (R425), with the other end of the ninth resistor (R425) connected to the power supply. The enable pin (EN) of the DCDC chip U37 has a lower voltage threshold of 0.9V and an upper voltage threshold of 1.5V. The sixth resistor (R316) has a resistance of 12.4KΩ, the seventh resistor (R318) has a resistance of 1KΩ, and the eighth resistor (R416) and the ninth resistor (R425) are all 10KΩ. Its working mechanism is as follows: (1) When the software program controls the GPIO (1D23 / GPIO1_B3_u) signal to be high (the hardware default pull-up resistor is 10K (R425), which is high), the second NPN transistor (Q19) is in the conducting state, and the level of the EN pin (pin 5) of the DCDC is 0V, which is less than Ven_min (0.9V), so that the voltage of the DCDC is not output; (2) When the software program controls the GPIO (1D23 / GPIO1_B3_u) signal to be high, the second NPN transistor (Q19) is in the conducting state, and the level of the EN pin (pin 5) of the DCDC is 0V, which is less than Ven_min (0.9V), so that the voltage of the DCDC is not output; (3) When the software program controls the GPIO (1D23 / GPIO1_B3_u) signal to be high, the second NPN transistor (Q19) is in the conducting state, and the level of the EN pin (pin 5) of the DCDC is 0V, which is less than Ven_min (0.9V), so that the voltage of the DCDC is not output; When the _B3_u) signal is low, the second NPN transistor (Q19) is in the off state, and the level of the EN pin (pin 5) of the DCDC is 1.82V, which is greater than Ven_max (1.5V), thus controlling the voltage output of the DCDC; (3) It is necessary to use a GPIO (1D23 / GPIO1_B3_u) to control the enable of the DCDC by software program: Since the default output of the DCDC is 3.3V, if a domestic version of the 4G / 5G module with a 3.8V power supply is mistakenly connected, the 4G / 5G module will work abnormally. Then try to adjust the output voltage of the DCDC to 3.8V, and the 4G / 5G module will still work abnormally. At this time, software program is needed to control the enable of the DCDC to restart the DCDC power supply output of 3.8V, and the 4G / 5G module will work normally. The core circuit of this invention is constructed using discrete components such as MMBT3904 transistors, conventional resistors and capacitors, and general-purpose DC-DC chips, eliminating the need for expensive integrated chips and significantly reducing material costs. All components are commercially available models, ensuring convenient procurement and stable supply. Furthermore, the circuit connections are simple, and the PCB design is compact, reducing manufacturing and process control difficulties, making it ideal for mass production. The DC-DC enable control circuit of this invention not only achieves precise start and stop of voltage output but also incorporates a misconnection protection mechanism. This includes cutting off power supply when the enable terminal is pulled low due to module mismatch, preventing module burnout. For module malfunctions caused by voltage mismatch, restarting the DC-DC converter via software control restores normal operation without manual power disconnection, improving equipment stability and maintenance convenience.

[0023] The USB communication selection circuit is connected to the USB communication pin of the Mini PCIe interface (CON6) to switch between USB 2.0 and USB 3.2 bus communication modes. Figure 2In this circuit, two capacitors (C562 and C563) and three resistors (R175, R176, and R305) are used. By selectively mounting these two capacitors and three resistors, the 5G module can communicate via either USB 2.0 or USB 3.2 bus. The specific connection relationship is as follows: The USB differential signal receive pin (USB2HUB3RXN) of the Mini PCIe interface connector (CON6) is connected to one end of the eleventh resistor (R176), and the USB differential signal transmit pin (USB2HUB3RXP) is connected to one end of the tenth resistor (R175). The other end of the eleventh resistor (R176) is connected to the PERn0 pin, and the other end of the tenth resistor (R175) is connected to the PERp0 pin. One end of the twelfth resistor (R305) is connected to the RESET INn pin, and the other end is connected to the PETp0 pin. The USB differential signal receiving pin (USB2HUB3TXN) of the PCIe interface connection terminal (CON6) is connected to one end of the first capacitor (C562), and the USB differential signal transmitting pin (USB2HUB3TXP) is connected to one end of the second capacitor (C563); the other end of the first capacitor (C562) is connected to the PETn0 pin, and the other end of the second capacitor (C563) is connected to the PETp0 pin; its working mechanism is as follows: (1) When the actual capacitor C562, capacitor C563, resistor R175 and resistor R176 are selected, and the unused resistor R305 is selected, the 5G module can communicate through the USB3.2 bus; (2) When the unused capacitor C562, capacitor C563, resistor R175 and resistor R176 are selected, and the actual resistor R305 is selected, the 5G module can communicate through the USB2.0 bus.

[0024] The Mini PCIe interface connector (CON6), model AAA-PCI-047-K01, serves as a unified interface carrier for connecting domestic and international 4G / 5G modules. It is connected to the output of the power supply voltage switching circuit (VDDADJ4G) and the USB communication selection circuit, respectively, to realize the physical connection and signal transmission between the module and the circuit.

[0025] This invention enables seamless power supply switching via software through discrete components, achieving compatibility with domestic and international Mini PCIe 4G / 5G modules; and allows for easy implementation of optional USB 2.0 or USB 3.2 bus communication for 5G modules through the selective mounting of discrete components.

[0026] The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface of the present invention also includes an I2S bus audio communication selection circuit, which includes a first selectable resistor R414, a second selectable resistor R415, a third selectable resistor R392, and a fourth selectable resistor R391. One end of the first selectable resistor R414 is connected to the Reserved 1 pin of the Mini PCIe interface connection terminal (CON6); one end of the second selectable resistor R415 is connected to the Reserved 2 pin of the Mini PCIe interface connection terminal (CON6); one end of the third selectable resistor R392 is connected to the Reserved 3 pin of the Mini PCIe interface connection terminal (CON6); and one end of the fourth selectable resistor R391 is connected to the Reserved 3 pin of the Mini PCIe interface connection terminal (CON6). Connect the Reserved4 pin of the PCIe interface connector (CON6) to the other end of the four optional surface-mount resistors, which are respectively connected to the onboard CPU. The onboard CPU model can be selected as RK3576J. When the four optional surface-mount resistors are solid resistors, the 4G module can perform audio communication through the I2S bus. When the four optional surface-mount resistors are unmounted resistors, the 4G module cannot perform audio communication through the I2S bus.

[0027] The circuit operation of this invention is as follows: First, according to the USB communication protocol of the 4G and 5G modules to be connected, the corresponding components of the USB communication selection circuit are selected to preset the USB 2.0 or USB 3.2 communication mode; simultaneously, according to the audio function requirements of the terminal product, the audio function status of the 4G module is configured through the four select resistors of the I2S bus audio communication selection circuit (either physically mounted or unmounted); then, the domestic and foreign 4G and 5G modules are physically connected to this compatible circuit through the Mini PCIe interface connection terminal (CON6); then, adaptation is performed through the corresponding program; subsequently, the corresponding level is output through the first GPIO control terminal to control the preset adaptation power supply voltage of the power supply voltage switching circuit—if it is a foreign module, the first GPIO control terminal outputs a low level, the first NPN transistor is turned off, the second resistor alone forms a voltage divider network with the first resistor, and the DC-DC chip is preset to output 3.3V; if it is a domestic module, the first GPIO control terminal outputs a high level, the first NPN transistor is turned on, the second resistor and the third resistor are connected in parallel and then form a voltage divider network with the first resistor, and the DC-DC chip is preset to output 3.8V. The DC chip is not currently outputting voltage; it needs to be triggered by the enable signal to start outputting. After the voltage preset is completed, a low level is output through the second GPIO control terminal to adjust the voltage of the DC-DC chip's enable pin to above the threshold limit, enabling the DC-DC enable control circuit to start the DC-DC chip and provide stable power to the module. The 4G and 5G modules complete initialization. Finally, the 4G and 5G modules establish a connection with the host device through the preset USB communication link to achieve data transmission. If the audio function is enabled, the 4G module can perform audio communication through the I2S bus. If a power supply mismatch occurs, the DC-DC enable is controlled through the second GPIO control terminal, and restarting the DC-DC power supply will restore normal operation.

[0028] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. In short, all variations made within the scope of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A circuit compatible with domestic and international 4G and 5G modules based on a Mini PCIe interface, characterized in that: It includes a power supply voltage switching circuit, a DC-DC enable control circuit, a Mini PCIe interface connector, a DC-DC chip, an inductor, and a filter capacitor bank. The power supply voltage switching circuit is connected to the feedback pin of the DC-DC chip and is used to output a power supply voltage adapted to domestic and foreign 4G / 5G modules to the Mini PCIe interface connector. The DC-DC enable control circuit is connected to the enable pin of the DC-DC chip and is used to control the voltage output state of the DC-DC chip. The Mini PCIe interface connector is used to interface with domestic and foreign 4G / 5G modules.

2. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 1, characterized in that: The power supply voltage switching circuit includes a first NPN transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor. The feedback pin of the DC-DC chip is connected to one end of the first resistor and one end of the second resistor, respectively, and the other end of the second resistor is grounded. The other end of the first resistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the collector of the first NPN transistor. The base of the first NPN transistor is connected to the first GPIO control terminal through the fourth resistor, and the base is also connected to one end of the fifth resistor, which is a pull-down resistor, and its other end is grounded. The emitter of the first NPN transistor is directly grounded.

3. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 2, characterized in that: When the first GPIO control terminal outputs a low level, the first NPN transistor is turned off, and the second resistor forms a voltage divider network with the first resistor alone. The DC-DC chip outputs a power supply voltage that is compatible with foreign 4G / 5G modules. When the first GPIO control terminal outputs a high level, the first NPN transistor is turned on, and the second resistor and the third resistor are connected in parallel and then form a voltage divider network with the first resistor. The DC-DC chip outputs a power supply voltage that is compatible with domestic 4G / 5G modules.

4. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 1, characterized in that: The DC-DC enable control circuit includes a second NPN transistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor. The enable pin of the DC-DC chip is connected to the collector of the second NPN transistor, one end of the sixth resistor, and one end of the eighth resistor, respectively. The other end of the eighth resistor is connected to the power supply. The base of the second NPN transistor is connected to the second GPIO control terminal through the seventh resistor. The base is also connected to one end of the ninth resistor, and the other end of the ninth resistor is connected to the power supply.

5. The compatible circuit for domestic and international 4G and 5G modules based on the Mini PCIe interface according to claim 4, characterized in that: The enable pin of the DC-DC chip has a lower voltage threshold and an upper voltage threshold. When the voltage of the enable pin is less than the lower voltage threshold, the DC-DC chip stops outputting voltage. When the voltage of the enable pin is greater than the upper voltage threshold, the DC-DC chip starts outputting voltage. Furthermore, by controlling the enable of the DC-DC chip through the second GPIO control terminal, the DC-DC power supply can be restarted to adapt to different version modules.

6. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 1, characterized in that: The DC-DC chip is a wide voltage regulation DC-DC converter chip. Its power input pin is connected to a first power supply voltage and a second power supply voltage. The switch output pin is connected to the output terminal through an inductor. The output terminal is connected in parallel with a first filter capacitor bank. The power input pin output terminal is also connected in parallel with a second filter capacitor bank.

7. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 1, characterized in that: It also includes a USB communication selection circuit, which is connected to the USB communication pin of the Mini PCIe interface connection terminal and is used to switch between USB 2.0 and USB 3.2 bus communication modes.

8. The compatible circuit for domestic and international 4G and 5G modules based on the Mini PCIe interface according to claim 7, characterized in that: The USB communication selection circuit includes a first capacitor, a second capacitor, a tenth resistor, an eleventh resistor, and a twelfth resistor. The USB differential signal receiving pin of the Mini PCIe interface is connected to one end of the eleventh resistor, and the USB differential signal transmitting pin is connected to one end of the tenth resistor. The other end of the eleventh resistor is connected to the PERn0 pin, and the other end of the tenth resistor is connected to the PERp0 pin. One end of the twelfth resistor is connected to the RESET INn pin, and the other end is connected to the PETp0 pin. The USB differential signal receiving pin of the Mini PCIe interface is connected to one end of the first capacitor, and the USB differential signal transmitting pin is connected to one end of the second capacitor. The other end of the first capacitor is connected to the PETn0 pin, and the other end of the second capacitor is connected to the PETp0 pin.

9. The domestic and international 4G and 5G module compatible circuit based on the Mini PCIe interface according to claim 1, characterized in that: It also includes an I2S bus audio communication selection circuit, which includes four selectable resistors. One end of each selectable resistor is connected to one of the four reserved pins of the Mini PCIe interface, and the other end is connected to the onboard CPU. By selecting whether the preset selectable resistors are installed or not, the audio communication function between the 4G module and the I2S bus can be enabled or disabled.

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