Earphone charging circuit, earphone charging control method, chip and earphone charging box

Abstract

The application is suitable for the technical field of charging control, and provides an earphone charging circuit, an earphone charging control method, a chip and an earphone charging box. The earphone charging circuit comprises a voltage conversion module, a load switch and current detection module, a comparison module and a digital control module. The voltage conversion module, the load switch and current detection module and the comparison module are electrically connected with the digital control module. The load switch and current detection module is electrically connected with the voltage conversion module and the comparison module respectively. The load switch and current detection module is electrically connected with the earphone. The application directly completes the current threshold comparison through the comparison module, avoids the hardware requirements of analog-to-digital conversion, multi-bit signal transmission and complex digital operation in the prior art from the source, simplifies the overall hardware circuit structure, reduces the number of peripheral devices, reduces the occupation of internal digital resources of the chip, and reduces the hardware material and chip design cost.

Description

Technical Field

[0001] This application belongs to the field of charging control technology, and in particular relates to an earphone charging circuit, an earphone charging control method, a chip, and an earphone charging case. Background Technology

[0002] TWS (True Wireless Stereo) earbuds come with a charging case to replenish the earbuds' power. The earbuds typically integrate a linear charging circuit, whose losses are determined by the voltage difference between the charging case's output voltage and the earbud's battery voltage. A larger voltage difference leads to higher heat loss and lower charging efficiency. To address this, the industry has proposed a voltage-following charging solution. This solution dynamically adjusts the charging case's output voltage to be only slightly higher than the earbud's battery voltage, thus reducing voltage difference losses. Existing voltage-following charging solutions rely on charging current sampling feedback for voltage regulation. Compared to communication-based, purely analog loop solutions, this offers lower system complexity. However, these existing solutions require analog-to-digital conversion of the sampled charging current, multi-bit digital signal transmission and processing, necessitating the use of an ADC (Analog Converter). to Digital converters (Analog-to-Digital converters) have complex hardware circuit structures, including conversion circuits and multi-channel digital transmission lines. Summary of the Invention

[0003] This application provides an earphone charging circuit, an earphone charging control method, a chip, and an earphone charging case. It can solve the problem that voltage-following charging schemes require analog-to-digital conversion of the sampled charging current, multi-bit digital signal transmission and processing, and require matching ADC conversion circuits and multi-channel digital transmission lines, resulting in a cumbersome hardware circuit structure.

[0004] In a first aspect, embodiments of this application provide an earphone charging circuit, including a voltage conversion module, a load switch / current detection module, a comparison module, and a digital control module. The voltage conversion module, the load switch / current detection module, and the comparison module are all electrically connected to the digital control module. The load switch / current detection module is electrically connected to both the voltage conversion module and the comparison module. The load switch / current detection module is used to be electrically connected to the earphone. The voltage conversion module receives the battery voltage from the earphone charging case and converts it into a supply voltage according to the start signal and voltage setting signal output by the digital control module. The load switch and current detection module transmits the supply voltage to the earphones according to the switch signal output by the digital control module, while simultaneously collecting the charging current of the earphones and outputting a sampled current to the comparison module. The comparison module compares the sampled current with a preset threshold current output by the digital control module and outputs a low current signal when the sampled current is less than the preset threshold current. After receiving the low current signal, the digital control module determines the relationship between the current supply voltage output by the voltage conversion module and the preset maximum output voltage. When the current supply voltage output is equal to the preset maximum output voltage, the digital control module controls the voltage conversion module to maintain the preset maximum output voltage to continuously charge the earphones. When the current supply voltage output is less than the preset maximum output voltage, the digital control module sends a boost adjustment signal to the voltage conversion module to control the supply voltage to increase by a preset step size, so as to achieve voltage-following charging of the earphones.

[0005] In one possible implementation of the first aspect, the digital control module includes a preset option unit and a first digital control unit, the first digital control unit being electrically connected to the preset option unit, the voltage conversion module, the load switch / current detection module, and the comparison module, respectively; the voltage conversion module, the load switch / current detection module, the comparison module, the preset option unit, and the first digital control unit are all integrated into the same chip; The preset option unit is used to store the preset threshold current, the preset maximum output voltage, and the preset step size, and transmit the preset threshold current, the preset maximum output voltage, and the preset step size to the first digital control unit; the first digital control unit is used to receive the low current signal, output the start signal and the boost adjustment signal to the voltage conversion module, output the switching signal to the load switch and current detection module, and output the preset threshold current to the comparison module.

[0006] In one possible implementation of the first aspect, the digital control module includes a register array unit and a second digital control unit, wherein the register array unit is electrically connected to the second digital control unit, the voltage conversion module, the load switch and current detection module, and the comparison module, respectively; the voltage conversion module, the load switch and current detection module, the comparison module, and the register array unit are all integrated in the same chip, and the second digital control unit is disposed outside the chip; The second digital control unit interacts with the register array unit via a communication bus; the register array unit includes a status register and a control register, and the low current signal output by the comparison module is stored in the status register; the second digital control unit reads the low current signal in the status register and writes control instructions to the control register to configure the preset maximum output voltage, the preset threshold current, and the power supply voltage output by the voltage conversion module.

[0007] In one possible implementation of the first aspect, the voltage conversion module includes a BOOST boost circuit or a BUCK-BOOST buck-boost circuit; when the voltage conversion module uses a BOOST boost circuit and the supply voltage is less than the battery voltage, the BOOST boost circuit operates in pass-through mode.

[0008] In one possible implementation of the first aspect, the load switch and current detection module includes a load switch unit and a current detection unit, wherein the load switch unit is electrically connected to the current detection unit, the voltage conversion module, the digital control module, and the earphone, and the current detection unit is electrically connected to the comparison module. The load switch unit is used to turn on according to the switch signal, so that the power supply voltage is transmitted to the earphone; the current detection unit is used to collect the charging current of the earphone and output the sampled current to the comparison module.

[0009] In a second aspect, embodiments of this application provide a headphone charging control method, applied to the headphone charging circuit described in any one of the first aspects, executed by a digital control module in the headphone charging circuit, the method comprising: The digital control module establishes communication with the earphone to obtain the battery voltage of the earphone; based on the battery voltage of the earphone, it configures the initial power supply voltage parameters for the voltage conversion module to complete the charging initialization parameter settings. A start signal and a voltage setting signal are output to the voltage conversion module so that the voltage conversion module converts the battery voltage of the earphone charging case into the output power supply voltage according to the configured initial power supply voltage parameters. A switching signal is output to the load switch and current detection module to enable the load switch and current detection module and supply the power supply voltage to the earphone; A preset threshold current is output to the comparison module so that the comparison module can compare the sampled current collected by the load switch and current detection module with the preset threshold current. The comparison module receives a low current signal when the sampling current is less than the preset threshold current, and determines the relationship between the current power supply voltage output by the voltage conversion module and the preset maximum output voltage. When the current output supply voltage is equal to the preset maximum output voltage, the voltage conversion module is controlled to maintain the preset maximum output voltage to continuously charge the earphone; When the current output supply voltage is less than the preset maximum output voltage, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size, so as to realize voltage-following charging of the earphone.

[0010] In one possible implementation of the second aspect, when the digital control module fails to establish communication with the earphone, a no-communication initialization process is executed, the no-communication initialization process including: Set the initial power supply voltage of the voltage conversion module to a preset minimum output voltage; The low current signal output by the comparison module is read according to the preset polling cycle; If the low current signal is detected, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size, and the output of the comparison module is polled again until the low current signal is no longer detected, thus completing the charging initialization.

[0011] In one possible implementation of the second aspect, the preset polling period includes a first polling period and a second polling period. During the charging initialization process, the low current signal is polled and read according to the first polling period. After the charging initialization is completed, the polling period is switched to the second polling period to read the low current signal. The first polling period is shorter than the second polling period.

[0012] Thirdly, embodiments of this application provide a chip including a battery pin, a power pin, an output pin, a ground pin, and a voltage conversion module, a load switch / current detection module, and a comparison module in the headphone charging circuit described in any one of the first aspects. The battery pin is electrically connected to the input terminal of the voltage conversion module, the power pin is electrically connected to the output terminal of the voltage conversion module and the input terminal of the load switch / current detection module, and the output pin is electrically connected to the output terminal of the load switch / current detection module and the headphone.

[0013] Fourthly, embodiments of this application provide an earphone charging case, including a charging case battery and an earphone charging circuit as described in any one of the first aspects; the positive terminal of the charging case battery is electrically connected to the input terminal of a voltage conversion module, and the negative terminal of the charging case battery is grounded.

[0014] The beneficial effects of the embodiments in this application compared with the prior art are: This application provides an earphone charging circuit, which includes a voltage conversion module, a load switch / current detection module, a comparison module, and a digital control module. During operation, the voltage conversion module receives the battery voltage from the earphone charging case and converts it into a power supply voltage for the earphones based on the start signal and voltage setting signal output by the digital control module. The load switch / current detection module conducts upon receiving the switch signal from the digital control module, supplying the power supply voltage to the earphones. Simultaneously, it collects the charging current of the earphones in real time and outputs the collected sampled current to the comparison module. The comparison module receives the sampled current and compares it with a preset threshold current set by the digital control module. When the sampled current is less than the preset threshold current, it indicates insufficient voltage difference between the power supply voltage and the earphone battery, resulting in a low charging current for the earphones. In this case, the comparison module outputs a low current signal to the digital control module. This low current signal only represents the magnitude of the sampled current relative to the preset threshold current and is a single-bit logic signal. After receiving the low current signal, the digital control module further determines the relationship between the current supply voltage of the voltage conversion module and the preset maximum output voltage. If the current supply voltage has reached the preset maximum output voltage, the module controls the voltage conversion module to maintain the preset maximum output voltage to continuously charge the earphones. If the current supply voltage is still less than the preset maximum output voltage, indicating that the output voltage has not yet reached the boost limit, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size. This dynamically adjusts the output supply voltage to achieve voltage-following charging of the earphones, allowing the output voltage of the charging case to match the earphone battery voltage, reducing the voltage difference in the linear charging circuit inside the earphones, reducing heat loss during charging, and improving charging efficiency.

[0015] Therefore, it can be seen that the headphone charging circuit provided in this application, after the load switch and current detection module completes current sampling, does not send the analog sampled current to the ADC for analog-to-digital conversion. Instead, the comparison module directly performs current magnitude comparison, outputting only a single-bit low-current signal representing the current magnitude to the digital control module. The entire process eliminates the need for analog... In the digital conversion stage, there is no need to configure an ADC conversion circuit, transmit multi-bit current sampling data, or lay out multi-channel digital transmission lines. The digital control module does not need to process a large amount of sampled digital data; it can complete the voltage regulation decision based solely on a single-bit logic signal combined with the current output voltage. Therefore, the technical approach of this application, which directly performs current threshold comparison through a comparison module, avoids the hardware requirements of analog-to-digital conversion, multi-bit signal transmission, and complex digital calculations found in existing solutions. This simplifies the overall hardware circuit structure, reduces the number of external components, lowers the occupation of internal chip digital resources, reduces hardware material and chip design costs, and is more suitable for the miniaturized product design requirements of TWS earphone charging cases.

[0016] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic block diagram of an earphone charging circuit provided in one embodiment of this application; Figure 2 This is a schematic block diagram of an earphone charging circuit provided in another embodiment of this application; Figure 3 This is a schematic block diagram of an earphone charging circuit provided in another embodiment of this application; Figure 4 This is a schematic flowchart of an embodiment of the headphone charging control method provided in this application; Figure 5 This is a flowchart of a headphone charging control method for establishing communication with headphones according to an embodiment of this application; Figure 6 This is a flowchart of a communication-free initialization process provided in an embodiment of this application; Figure 7 This is a flowchart of a headphone charging control method provided in one embodiment of this application when communication with the headphone cannot be established.

[0019] In the diagram: 11. Voltage conversion module; 12. Load switch and current detection module; 13. Comparison module; 14. Digital control module; 141. Preset option unit; 142. First digital control unit; 143. Register array unit; 144. Second digital control unit. Detailed Implementation

[0020] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0021] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0022] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0024] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0026] TWS earbuds typically consist of the earbuds themselves and a charging case. The charging case contains a large-capacity battery. When the earbuds are low on power, placing them in the charging case allows the case to recharge them, thus improving the overall battery life of the wireless earbuds. Due to limitations such as small battery capacity, low charging current, and limited internal space, most TWS earbuds incorporate a linear charging circuit. According to the operating characteristics of this linear charging circuit, the voltage difference between the charging case's output voltage and the earbud's battery voltage is entirely converted into heat dissipation in the linear charging circuit. The larger the voltage difference, the greater the heat loss and the lower the charging efficiency. To improve charging efficiency, the industry has proposed a voltage-following charging strategy. This involves dynamically adjusting the charging case's output voltage so that it is only slightly higher than the earbud's battery voltage, thereby reducing the voltage difference in the linear charging circuit and minimizing heat loss. Currently, existing voltage-following charging solutions mainly fall into three categories: The first category relies on the periodic communication between the charging case and the earphones to obtain the real-time voltage of the earphone battery, thereby adjusting the output voltage of the charging case. However, the communication process requires interrupting charging, and frequent communication will reduce charging efficiency. It also requires the charging case and the earphone's main control protocol to be compatible. The second category is a pure analog circuit solution, which uses the characteristics of constant current load switches and the linear charging circuit of the earphones to achieve voltage following. However, multiple sets of feedback loops are nested, making the loop stability design difficult. The third category achieves voltage regulation by sampling the earphone charging current. Compared with the first two categories, the overall system complexity is lower and the design difficulty is less, with more prominent comprehensive advantages. However, the existing implementation of this type requires analog-to-digital conversion, multi-bit digital signal transmission, and computational processing of the sampled charging current. It requires the configuration of ADC conversion circuits and multi-channel digital transmission lines, resulting in a cumbersome hardware circuit architecture.

[0027] This application belongs to the third category of solutions mentioned above and provides an earphone charging circuit. The circuit includes a voltage conversion module, a load switch / current detection module, a comparison module, and a digital control module. During operation, the voltage conversion module receives the battery voltage from the earphone charging case and converts it into a power supply voltage for powering the earphones based on the start signal and voltage setting signal output by the digital control module. The load switch / current detection module conducts after receiving the switch signal from the digital control module, supplying the power supply voltage to the earphones. Simultaneously, it collects the charging current of the earphones in real time and outputs the collected sampled current to the comparison module. The comparison module receives the sampled current and compares it with a preset threshold current set by the digital control module. When the sampled current is less than the preset threshold current, it indicates insufficient voltage difference between the power supply voltage and the earphone battery, resulting in a low charging current for the earphones. In this case, the comparison module outputs a low current signal to the digital control module. This low current signal only represents the magnitude of the sampled current relative to the preset threshold current and is a single-bit logic signal. After receiving the low current signal, the digital control module further determines the relationship between the current supply voltage of the voltage conversion module and the preset maximum output voltage. If the current supply voltage has reached the preset maximum output voltage, the module controls the voltage conversion module to maintain the preset maximum output voltage to continuously charge the earphones. If the current supply voltage is still less than the preset maximum output voltage, indicating that the output voltage has not yet reached the boost limit, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size. This dynamically adjusts the output supply voltage to achieve voltage-following charging of the earphones, allowing the output voltage of the charging case to match the earphone battery voltage, reducing the voltage difference in the linear charging circuit inside the earphones, reducing heat loss during charging, and improving charging efficiency.

[0028] Therefore, it can be seen that the headphone charging circuit provided in this application, after the load switch and current detection module completes current sampling, does not send the analog sampled current to the ADC for analog-to-digital conversion. Instead, the comparison module directly performs current magnitude comparison, outputting only a single-bit low-current signal representing the current magnitude to the digital control module. The entire process eliminates the need for analog... In the digital conversion stage, there is no need to configure an ADC conversion circuit, transmit multi-bit current sampling data, or lay out multi-channel digital transmission lines. The digital control module does not need to process a large amount of sampled digital data; it can complete the voltage regulation decision based solely on a single-bit logic signal combined with the current output voltage. Therefore, the technical approach of this application, which directly performs current threshold comparison through a comparison module, avoids the hardware requirements of analog-to-digital conversion, multi-bit signal transmission, and complex digital calculations found in existing solutions. This simplifies the overall hardware circuit structure, reduces the number of external components, lowers the occupation of internal chip digital resources, reduces hardware material and chip design costs, and is more suitable for the miniaturized product design requirements of TWS earphone charging cases.

[0029] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0030] Figure 1 A schematic block diagram of an earphone charging circuit according to an embodiment of this application is shown. See also... Figure 1 As shown, the headphone charging circuit includes a voltage conversion module 11, a load switch / current detection module 12, a comparison module 13, and a digital control module 14. The voltage conversion module 11, the load switch / current detection module 12, and the comparison module 13 are all electrically connected to the digital control module 14. The load switch / current detection module 12 is electrically connected to both the voltage conversion module 11 and the comparison module 13. The load switch / current detection module 12 is used to electrically connect to the headphone.

[0031] Specifically, during circuit operation, the voltage conversion module 11 receives the battery voltage BAT from the earphone charging case and converts it into a power supply voltage for powering the earphones according to the start signal and voltage setting signal output by the digital control module 14. The load switch and current detection module 12 turns on after receiving the switch signal output by the digital control module 14, and delivers the power supply voltage to the earphones. At the same time, it collects the charging current of the earphones in real time and outputs the collected sampling current ICS to the comparison module 13. After receiving the sampling current ICS, the comparison module 13 compares it with the preset threshold current set by the digital control module 14. When the sampling current ICS is less than the preset threshold current, it indicates that the voltage difference between the power supply voltage and the earphone battery is insufficient and the charging current of the earphones is small. At this time, the comparison module 13 outputs a low current signal (i.e., an effective low current signal, ILow=1) to the digital control module 14. The low current signal only indicates the magnitude of the sampling current ICS relative to the preset threshold current and is a single-bit (1-bit) logic signal. After receiving the low current signal, the digital control module 14 further determines the relationship between the current power supply voltage output by the voltage conversion module 11 and the preset maximum output voltage. If the current power supply voltage has reached the preset maximum output voltage, the voltage conversion module 11 is controlled to maintain the preset maximum output voltage to continuously charge the earphones. If the current power supply voltage is still less than the preset maximum output voltage, it indicates that the output voltage has not yet reached the boost limit. At this time, a boost adjustment signal is sent to the voltage conversion module 11 to control the power supply voltage to increase by a preset step size, thereby dynamically adjusting the output power supply voltage to achieve voltage-following charging of the earphones. This allows the output voltage of the charging case to match the earphone battery voltage BAT, reducing the voltage difference in the linear charging circuit inside the earphones, reducing heat loss during charging, and improving charging efficiency.

[0032] Therefore, it can be seen that the headphone charging circuit provided in this application, after the load switch and current detection module 12 completes current sampling, does not send the analog sampled current ICS to the ADC for analog-to-digital conversion. Instead, the comparison module 13 directly performs current magnitude comparison and only outputs a single-bit low current signal representing the current magnitude to the digital control module 14. The entire process eliminates the need for analog... In the digital conversion stage, there is no need to configure an ADC conversion circuit, transmit multi-bit current sampling data, or lay out multi-channel digital transmission lines. The digital control module 14 does not need to process a large amount of sampled digital data; it can complete the voltage regulation decision based solely on a single-bit logic signal combined with the current output voltage. Therefore, the technical means of this application, which directly performs current threshold comparison through the comparison module 13, avoids the hardware requirements of analog-to-digital conversion, multi-bit signal transmission, and complex digital calculations in existing solutions from the source. This simplifies the overall hardware circuit structure, reduces the number of peripheral components, lowers the occupation of internal chip digital resources, reduces hardware material and chip design costs, and is more suitable for the miniaturized product design requirements of TWS earphone charging cases.

[0033] It should be noted that when the sampling current ICS is greater than or equal to the preset threshold current, it indicates that the voltage difference between the power supply voltage and the headphone battery is sufficient, and the headphone can maintain a sufficient charging current. At this time, the comparison module 13 outputs an invalid low current signal, i.e., ILow=0. After receiving this signal, the digital control module 14 determines that the current power supply voltage is suitable for the headphone charging requirements and does not perform boost adjustment on the output voltage of the voltage conversion module 11.

[0034] The following is combined with Figure 2 and Figure 3 The working principle of the headphone charging circuit is explained in detail.

[0035] In one embodiment of this application, such as Figure 2 As shown, the digital control module 14 includes a preset option unit 141 and a first digital control unit 142. The first digital control unit 142 is electrically connected to the preset option unit 141, the voltage conversion module 11, the load switch and current detection module 12, and the comparison module 13, respectively. The voltage conversion module 11, the load switch and current detection module 12, the comparison module 13, the preset option unit 141, and the first digital control unit 142 are all integrated into the same chip.

[0036] Specifically, the preset option unit 141 stores various parameters required for the operation of this solution, including preset threshold current, preset maximum output voltage, and preset step size, and outputs these parameters to the first digital control unit 142. The preset option unit 141 can employ fuse adjustment or OTP (One-to-One Protocol). Time-Programmable (TPM) is used to implement chip configuration parameters. It generally does not use erasable and rewritable memory. It is mainly used to store the chip's fixed configuration parameters. Most of these parameters are determined at the chip manufacturing stage, but some can be written by the user during use.

[0037] The first digital control unit 142, as the main digital logic unit inside the chip, receives the low current signal output by the comparison module 13 on the one hand; on the other hand, it outputs a start signal and a boost adjustment signal to the voltage conversion module 11, outputs a switch signal to the load switch and current detection module 12, and also outputs a preset threshold current provided by the preset option unit 141 to the comparison module 13 for the comparison module 13 to complete the current comparison.

[0038] The first digital control unit 142 can employ an application-specific integrated circuit (ASIC). It can be implemented using fixed logic units in the form of Specific Integrated Circuits (ASICs), or it can be implemented using simplified microcontroller units (MCUs) combined with OTPs or MTPs (Multiple Logic Adapters). The architecture uses memory such as Time Programmable Memory (TPM). Because this embodiment integrates analog circuitry (voltage conversion module 11, load switch / current detection module 12, and comparison module 13) with digital circuitry (preset option unit 141 and first digital control unit 142) onto a single chip (charging box management chip), the chip cannot use a process with excessively small linewidths due to limitations in analog circuit technology. Therefore, using Flash ROM memory would result in higher chip area and manufacturing costs. This solution is generally only used in the early stages of product development. For mass-produced mature products, ASIC or MCU+OTP / MTP implementations are preferred to control chip costs. However, these implementations have limited flexibility and are more suitable for mature products where functional iterations are complete and extensive customization is not required.

[0039] Furthermore, this embodiment integrates analog and digital circuits onto a single chip. The sampled current ICS acquired by the load switch and current detection module 12 is sent to the comparison module 13. The comparison module 13 compares the sampled current ICS with a preset threshold current from the first digital control unit 142 and outputs a low current signal to the first digital control unit 142. When the sampled current ICS is less than the preset threshold current, the low current signal is enabled. The chip has external BAT, PMID, VOUT, and GND pins. The BAT pin is used to connect the battery of the earphone charging case. The PMID pin is the output of the voltage conversion module 11 and also serves as the input of the load switch and current detection module 12. An external output capacitor is connected to the PMID pin and then to the ground of the earphone charging case. The VOUT pin is the power output pin of the load switch and current detection module 12 and is used to connect to the input of the wireless earphone. The GND pin is the chip ground pin and is connected to the ground of the earphone charging case.

[0040] In one embodiment of this application, such as Figure 3 As shown, the digital control module 14 includes a register array unit 143 and a second digital control unit 144. The register array unit 143 is electrically connected to the second digital control unit 144, the voltage conversion module 11, the load switch and current detection module 12, and the comparison module 13, respectively. The voltage conversion module 11, the load switch and current detection module 12, the comparison module 13, and the register array unit 143 are all integrated into the same chip, while the second digital control unit 144 is located outside the chip.

[0041] Specifically, the second digital control unit 144 communicates with the register array unit 143 via a communication bus. The register array unit 143 includes two types of registers: a status register and a control register. The low current signal output by the comparison module 13 is stored in the status register for external units to read. The second digital control unit 144 can read the low current signal stored in the status register and simultaneously write control instructions to the control register. Through the written control instructions, it configures the preset maximum output voltage and preset threshold current, and adjusts the power supply voltage output by the voltage conversion module 11.

[0042] In this embodiment, in addition to the register body, the register array unit 143 also integrates supporting digital logic circuits to complete the necessary logic processing inside the chip. The charging case management chip retains the same BAT pin, PMID pin, VOUT pin, and GND pin as in the previous embodiment; the BAT pin is used to connect the battery of the earphone charging case, the PMID pin is the output terminal of the voltage conversion module 11, and an external capacitor is connected to the ground of the earphone charging case; the VOUT pin serves as the power output pin of the load switch and current detection module 12, used to connect to the input terminal of the wireless earphone; the GND pin is the chip ground pin. The load switch and current detection module 12 outputs the sampled current ICS to the comparison module 13. The comparison module 13 compares the sampled current ICS with a preset threshold current and outputs a low current signal, which is then written into the status register inside the register array unit 143.

[0043] The external second digital control unit 144 is an independent circuit unit, which can be an MCU, DSP (Digital Signal Processor), or FPGA (Field Application FPGA). The second digital control unit 144 is implemented using devices such as Field-Programmable Gate Array (FPGA). The communication bus between the second digital control unit 144 and the internal register array unit 143 can use common communication protocols such as I2C or SPI. When using the I2C bus, the register array unit 143 needs to be configured with I2C slave logic to complete bus interaction. The second digital control unit 144 undertakes all the control logic for voltage-following charging. By reading and writing to the register array unit 143, it completes signal reading and parameter configuration, thereby realizing the voltage-following charging control method of this application.

[0044] Compared to the aforementioned solution that integrates the digital control unit on-chip, this embodiment places the main control functions outside the chip, which increases the overall material cost, but the solution is more flexible. The external second digital control unit 144 can be flexibly programmed to facilitate the realization of various customized functional requirements and adapt to more product development scenarios.

[0045] In summary, the two aforementioned embodiments correspond to two different architectural schemes: the monolithic integrated scheme with the digital control unit integrated inside the chip is more suitable for product manufacturers with limited system development capabilities. The chip design manufacturer completes the development of the core control functions, and the product manufacturer only needs to add a few peripheral components to realize the whole function; while the scheme with the digital control unit externally can flexibly customize the functions according to the actual needs of the product during the system development stage, but the hardware cost of the external independent control chip itself is high, and the cost of some selections may even be higher than that of the charging box management chip itself.

[0046] Next, the specific implementation schemes of the three modules, namely voltage conversion module 11, load switch and current detection module 12, and comparison module 13, will be described.

[0047] In one embodiment of this application, the voltage conversion module 11 may be a BOOST boost circuit or a BUCK circuit. The BOOST boost circuit, with voltage conversion module 11 taking the charging box battery voltage BAT as input, has its output supply voltage adjustable in real time by digital control module 14. When voltage conversion module 11 adopts the BOOST boost circuit architecture and the set supply voltage is less than the charging box battery voltage BAT, the BOOST boost circuit operates in pass-through mode.

[0048] In one embodiment of this application, the load switch and current detection module 12 includes a load switch unit and a current detection unit. The load switch unit is electrically connected to the current detection unit, the voltage conversion module 11, the digital control module 14, and the headphone, respectively. The current detection unit is electrically connected to the comparison module 13.

[0049] Specifically, the load switch unit can be turned on according to the switching signal output by the digital control module 14, supplying the power supply voltage output by the voltage conversion module 11 to the headphones. The load switch unit can include a load switch, the main body of which is a transistor that meets the requirements of a high current load, i.e., an analog switch, which is controlled by the digital control module 14 to enable and disable. The current detection unit is used to collect the charging current of the headphones and output the sampling current ICS to the comparison module 13. Furthermore, the load switch unit can also integrate overcurrent protection, short circuit protection and other protection functions to improve the operating safety of the headphone charging circuit.

[0050] In one embodiment of this application, the comparison module 13 receives the sampled current ICS output by the current detection unit, compares the sampled current ICS with the preset threshold current issued by the digital control module 14, and outputs a low current signal. At the analog integrated circuit implementation level, current signal comparison is generally not performed directly. Instead, a set of matching resistors is used to convert the sampled current ICS and the preset threshold current into corresponding voltage signals, and then the two voltage signals are compared to obtain a valid / invalid low current signal. When the sampled current ICS is less than the preset threshold current, the comparison module 13 outputs a valid low current signal, i.e., ILow=1; when the sampled current ICS is greater than or equal to the preset threshold current, the comparison module 13 outputs an invalid low current signal, i.e., ILow=0.

[0051] It should be noted that the voltage conversion module 11, the load switch and current detection module 12, and the comparison module 13, i.e., the specific hardware circuit topology of the above analog circuit, belong to the well-known technology in the field of analog integrated circuits, and this application will not further describe their specific circuit structure.

[0052] In conclusion, Figure 2 and Figure 3 The two embodiments shown illustrate two different hardware architectures for headphone charging circuits, implementing the voltage-following charging control method of this application through an on-chip integrated first digital control unit 142 and an externally mounted second digital control unit 144. The core control logic of this voltage-following charging control method is as follows: the charging current of the headphones is sampled, and the sampled current ICS is compared with a preset threshold current; when the sampled current ICS drops below the preset threshold current, it is determined that the voltage difference between the power supply voltage output by the headphone charging case and the headphone battery is insufficient, thereby controlling the voltage conversion module 11 to increase the output power supply voltage to maintain a follow-up charging voltage suitable for headphone charging. The voltage-following charging control method of this application can adapt to different working scenarios and has various specific execution processes. The headphone charging control method of this application will be further described below with reference to embodiments.

[0053] In one embodiment of this application, the headphone charging circuit applied to any of the above embodiments is executed by the digital control module 14 in the headphone charging circuit. The digital control module 14 can be either an on-chip integrated first digital control unit 142 or an externally located second digital control unit 144. This method is generally divided into an initialization phase, a normal charging phase, and a termination phase after reaching the preset maximum output voltage. It is suitable for product scenarios where the headphone charging case can establish communication and interaction with the headphones. Figure 4 As shown, the specific control method includes steps S101 to S107.

[0054] In step S101, the digital control module establishes communication with the earphone to obtain the earphone's battery voltage; based on the earphone's battery voltage, it configures the initial power supply voltage parameters for the voltage conversion module to complete the charging initialization parameter settings.

[0055] Specifically, when the earbuds are detected as being placed in the charging case and a charging start command is triggered, the digital control module establishes a communication link with the earbuds and directly reads the battery voltage information from the earbuds through communication. Based on the obtained earbud battery voltage, the initial power supply voltage parameters corresponding to the voltage conversion module are configured, completing the initialization parameter configuration for charging. This step, by directly obtaining the earbud battery voltage through communication, can quickly determine the initial power supply voltage and shorten the initialization time.

[0056] It should be noted that this embodiment only needs to communicate with the earphone during the initialization phase. After the initialization is completed, it no longer relies on the earphone for communication. This avoids the problem of reduced charging efficiency caused by repeated communication and frequent interruption of charging in the existing solution in order to continuously obtain voltage.

[0057] Step S102: Output a start signal and a voltage setting signal to the voltage conversion module so that the voltage conversion module converts the battery voltage of the earphone charging case into the output power supply voltage according to the configured initial power supply voltage parameters.

[0058] Specifically, after completing the initial parameter configuration, the digital control module sends a start signal and a voltage setting signal to the voltage conversion module. The voltage conversion module receives these signals, uses the charging case battery voltage as input, performs voltage conversion according to the initial power supply voltage parameters configured in S101, and outputs the power supply voltage for powering the earphones. BOOST boost circuit; when the BOOST boost circuit is used and the configured supply voltage is less than the charging box battery voltage, the BOOST boost circuit operates in pass-through mode.

[0059] Step S103: Output a switching signal to the load switch and current detection module to turn on the load switch and current detection module and supply the power supply voltage to the headphones.

[0060] Specifically, the digital control module outputs a switching signal to the load switch / current detection module. Upon receiving the switching signal, the load switch unit conducts, and the supply voltage output by the voltage conversion module is transmitted to the headphones via the conducting load switch unit, providing charging power to the headphones. The load switch unit can also integrate overcurrent protection and short-circuit protection functions to improve the safety of the charging circuit.

[0061] Step S104: Output a preset threshold current to the comparison module so that the comparison module can compare the sampled current collected by the load switch and current detection module with the preset threshold current.

[0062] Specifically, the digital control module outputs a preset threshold current to the comparison module; the current detection unit inside the load switch / current detection module collects the charging current of the earphones in real time and outputs a sampled current to the comparison module. The comparison module compares the sampled current with the preset threshold current. In analog integrated circuit implementations, the comparison module generally does not directly compare currents, but instead converts the two currents into voltage signals through a matching resistor series before performing a voltage comparison and outputting a single-bit low current signal.

[0063] It should be noted that the transmission method of the low current signal differs for the two hardware architectures mentioned above: if the digital control module is the first digital control unit integrated inside the chip, the low current signal can be transmitted directly through the signal lines inside the chip; if it is the second digital control unit externally, the low current signal is first written into the status register inside the chip, and the external digital control unit can read it after receiving the notification through an interrupt, or obtain the signal by periodically polling the register.

[0064] Step S105: Receive the low current signal output by the comparison module when the sampling current is less than the preset threshold current, and determine the relationship between the current power supply voltage output by the voltage conversion module and the preset maximum output voltage.

[0065] Specifically, the current detection and comparison process is continuously performed during charging. When the sampled current is less than the preset threshold current, it indicates that the voltage difference between the current output supply voltage of the charging case and the earphone battery is insufficient, causing a drop in the earphone charging current. The comparison module outputs a valid low current signal. After receiving this low current signal, the digital control module executes the voltage judgment logic, comparing the current actual output supply voltage of the voltage conversion module with the preset maximum output voltage to determine subsequent control actions.

[0066] If the digital control module does not receive a valid low current signal, i.e., the sampled current is greater than or equal to the preset threshold current, it indicates that the current supply voltage and the voltage difference between the headphone battery are sufficient, the charging current meets the requirements, there is no need to adjust the output voltage, and the existing supply voltage is maintained to continue charging.

[0067] Step S106: When the current output power supply voltage is equal to the preset maximum output voltage, control the voltage conversion module to maintain the preset maximum output voltage to continuously charge the headphones.

[0068] Specifically, after the judgment in step S105, if the current power supply voltage has reached the preset maximum output voltage, the boost operation will no longer be performed. The digital control module controls the voltage conversion module to maintain the preset maximum output voltage and continue to output, entering the final charging stage, to avoid the overvoltage damage to the headphone components caused by unlimited voltage rise, until the charging is completed.

[0069] Step S107: When the current output power supply voltage is less than the preset maximum output voltage, a boost adjustment signal is sent to the voltage conversion module to control the power supply voltage to increase by a preset step size, so as to realize voltage-following charging of the headphones.

[0070] Specifically, if the current supply voltage is determined to be lower than the preset maximum output voltage, it indicates that there is still a boost adjustment margin. The digital control module then sends a boost adjustment signal to the voltage conversion module, controlling the supply voltage to increase by a preset step size. After the boost is complete, the process returns to continuous detection and comparison of the charging current, repeatedly executing the above logic to dynamically adjust the output supply voltage. This ensures that the charging case's output voltage is maintained slightly higher than the earphone battery voltage, achieving voltage-following charging, reducing differential heat loss in the earphone's internal linear charging circuit, and improving charging efficiency.

[0071] Figure 5 A flowchart of the headphone charging control method during communication with the headphones is shown. The trigger condition for this embodiment is: the charging case management chip detects that the headphones are placed inside the charging case, generates and sends a headphone charging start command, and formally initiates the voltage-following charging process.

[0072] Initialization phase: The charging case management chip can establish communication with the earphones. The digital control module directly obtains the battery voltage information of the earphones through communication interaction, and sets the initial output voltage of the voltage conversion module based on this information, starts the voltage conversion module to work, and completes the initialization work of voltage following charging.

[0073] It should be noted that in actual use cases, there will be situations where the headphones are unplugged and plugged back in. In this case, the restart logic of the charging process needs to be considered: when the headphones are unplugged, the previously saved follow voltage cannot be used to continue charging, nor can the complete communication initialization be re-executed until charging is finished.

[0074] For TWS earbuds with dual earbud configurations, the voltage-following charging logic typically uses the earbud with the higher battery voltage as a reference. If either earbud is removed during charging, the initialization process needs to be re-executed to complete the voltage-following adaptation for the remaining earbuds. Similarly, when a new earbud is reinserted into the charging case, a re-initialization is triggered to complete the voltage-following search and configuration again.

[0075] Furthermore, the process switching after plugging and unplugging the headphones involves the interactive negotiation logic between the master and slave charging devices. The aforementioned embodiments of this application mainly describe the control scheme of voltage following charging itself, and will not elaborate on the more complex negotiation and interaction details between the master and slave devices.

[0076] Normal charging phase: 1. The internal load switch / current detection module and comparison module of the chip continuously detect the charging current of the earphones, compare the sampled current with a preset threshold current, generate a low current signal, and transmit it to the digital control module. This low current signal is a single-bit logic signal, and the signal transmission method varies depending on the hardware architecture of the digital control module. When the digital control module is the first digital control unit integrated inside the chip, the low current signal can be transmitted directly through the chip's internal signal lines. When the second digital control unit is located outside the chip, the low current signal is first written to the chip's internal status register. The external second digital control unit can either receive interrupt notifications to read the signal in the register, or periodically poll the status register to obtain the low current signal without an interrupt mechanism.

[0077] 2. When the digital control module detects a low current signal indicating that the sampling current is greater than or equal to the preset threshold current, it determines that the current charging output voltage is suitable for the headphone charging needs, and there is no need to adjust the output voltage of the voltage conversion module.

[0078] 3. When the digital control module detects a low current signal indicating that the sampled current is less than the preset threshold current, it determines that the current output power supply voltage is insufficient. It further determines whether the current output power supply voltage of the voltage conversion module has reached the preset maximum output voltage. If it has not reached the preset maximum output voltage, it controls the voltage conversion module to increase the output voltage according to the preset step size, and then returns to the current continuous detection step.

[0079] 4. If the current output power supply voltage has reached the preset maximum output voltage, the process will enter the final stage.

[0080] Final stage: The control voltage conversion module maintains the preset maximum output voltage continuously to charge the headphones until the charging process is complete.

[0081] In one embodiment of this application, when the digital control module cannot establish communication with the earphones, a no-communication initialization process is executed. This embodiment is particularly suitable for hardware scenarios where the digital control unit is external, the chip lacks interrupt output capability, and the digital control module needs to actively poll and read the status register. When the charging case management chip detects that the earphones are placed in the charging case and issues a charging start command, due to a communication link abnormality, the digital control module cannot obtain the earphone battery voltage, and therefore executes the no-communication initialization process. Figure 6 As shown, the no-communication initialization process includes steps S108 to S110.

[0082] Step S108: Set the initial power supply voltage of the voltage conversion module to a preset minimum output voltage.

[0083] Specifically, since the headphone battery voltage cannot be obtained via communication, and there is no usable battery voltage reference information, the digital control module first configures the initial supply voltage of the voltage conversion module to a preset minimum output voltage (for example, the preset minimum output voltage can be 3.6V). This preset minimum output voltage will be lower than the actual voltage of the headphone battery in most operating conditions, resulting in insufficient voltage differential in the headphone charging circuit and a drop in charging current. After configuration, the charging circuit is kept open, and the load switch / current detection module continuously collects the headphone charging current. The comparison module compares the sampled current with a preset threshold current in real time and outputs the resulting low current signal; in the case of an external digital control unit architecture, the low current signal is written to the chip's internal status register.

[0084] Step S109: Read the low current signal output by the comparison module according to the preset polling cycle.

[0085] Specifically, in this scenario, the chip lacks interrupt notification capabilities and cannot proactively notify the digital control module when the low current signal state changes. Therefore, the digital control module needs to periodically read the low current signal according to a preset polling cycle. The polling cycle used during the initialization phase is denoted as T0. To speed up the initialization search, T0 is typically short, such as tens of milliseconds. This polling cycle needs to be longer than the chip's internal low current signal refresh cycle to ensure that a stable and valid signal can be read.

[0086] In step S110, if a low current signal is read, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size, and the output of the comparison module is polled again until no low current signal is read, thus completing the charging initialization.

[0087] Specifically, when the initial power supply voltage is set to the preset minimum output voltage, if the output voltage is insufficient and the sampling current is less than the preset threshold current, the digital control module will read a valid low current signal; this signal indicates that the voltage difference between the current power supply voltage and the earphone battery voltage is insufficient. At this time, the digital control module sends a boost adjustment signal to the voltage conversion module to raise the power supply voltage by a preset step.

[0088] After the voltage boost is complete, the digital control module continues to repeatedly read the low current signal according to the preset polling cycle; it then continuously executes the "maintain charging" function. Polling to read signals The process is to "boost the voltage when a low current signal is detected".

[0089] As the power supply voltage continues to rise, when the voltage difference between the power supply voltage output by the charging case and the earphone battery is sufficient, and the sampling current increases to be greater than or equal to the preset threshold current, a valid low current signal will no longer be output. The digital control module will not be able to read the low current signal, which means that the output voltage can now enable the internal linear charging circuit of the earphone to reach the target charging current, find the appropriate initial following voltage, and the no-communication initialization process ends.

[0090] After initialization is complete, the normal charging phase begins. The normal charging phase uses a different polling period T1. Because the normal charging period is long, T1 is much longer than the polling period T0 of the initialization phase, typically several seconds or even more than ten seconds, to reduce the polling overhead of the digital control module.

[0091] During the normal charging phase, the digital control module periodically reads low current signals: If no low current signal is read, it means that the charging current meets the requirements and the current output voltage is appropriate. Keep the output voltage of the voltage conversion module unchanged. When a low current signal is read, it indicates that the charging current has dropped and the current output voltage is insufficient. Then, it is further determined whether the current supply voltage has reached the preset maximum output voltage. If the preset maximum output voltage has not been reached, the supply voltage is increased by a preset step size, and the detection continues in a loop. If the preset maximum output voltage has been reached, the process enters the final stage.

[0092] During the final stage, the control voltage conversion module maintains the preset maximum output voltage continuously until the headphones finish charging.

[0093] It should be noted that during the final stage of voltage-following charging, the circuit maintains a preset maximum output voltage to continuously charge the headphones. This application determines the full charge status of the headphone battery by the magnitude of the charging current. The specific principle is as follows: The headphones integrate a linear charging circuit. Based on the inherent characteristics of the linear charging circuit, when the headphone battery voltage approaches the full charge voltage, the headphone charging current will continuously decrease; when the battery is fully charged, the linear charging circuit on the headphone side will automatically turn off, and the charging current will approach zero.

[0094] To address this, this application can pre-set a charging end threshold current within the chip. This charging end threshold current is significantly smaller than the aforementioned preset threshold current used for voltage follower regulation (the threshold corresponding to ILow). During charging, the load switch / current detection module continuously samples the headphone charging current in real time, and the comparison module compares the sampled current with the charging end threshold current. When the sampled current continuously decreases and eventually falls below the charging end threshold current, it can be determined that the headphone battery is fully charged. The system recognizes the completion of the charging task, terminates the current voltage follower charging process, and realizes the charging end determination. The full charge determination method can reuse the inherent current sampling and hardware comparison link of this application, without the need for additional detection circuitry. Without increasing hardware costs, it accurately achieves full charge determination, ensuring a complete and reliable charging process.

[0095] Figure 7 This diagram illustrates a flowchart of a headphone charging control method when communication with the headphones fails. This process is applicable to product scenarios where the charging case management chip cannot communicate with the headphones, the digital control unit is external, and the charging case management chip lacks interrupt output capability, requiring an external digital control unit to actively poll and read the status register. The trigger condition for this process is: the charging case management chip detects that the headphones are placed inside the charging case, issues a headphone charging start command, and the process officially begins.

[0096] Initialization phase: 1. Because it cannot communicate with the earphone and cannot obtain the earphone's battery voltage, the digital control module configures the initial output power supply voltage of the voltage conversion module to the preset minimum output voltage (for example, the preset minimum output voltage can be 3.6V).

[0097] 2. Keep the headphone charging circuit in the open state. The load switch and current detection module and comparison module inside the chip continuously detect the charging current, compare the sampled current with the preset threshold current, output a low current signal, and write the low current signal into the status register.

[0098] 3. Because the charging case management chip lacks an interrupt mechanism and cannot proactively send notifications when the low current signal status changes, the external digital control unit needs to periodically read the low current signal in the status register according to a polling cycle T0. To speed up the initialization search, the polling cycle T0 is set to a short duration, such as tens of milliseconds; the value of T0 needs to be greater than the refresh cycle of the low current signal in the chip's internal status register to ensure that a stable and valid signal is read.

[0099] 4. When the initial power supply voltage is set to the preset minimum output voltage, this voltage is usually lower than the headphone battery voltage. The digital control unit will read a valid low current signal. At this time, the digital control unit controls the voltage conversion module to raise the output power supply voltage according to the preset step size and cyclically executes "maintain charging". Waiting polling period T0 Read low current signal The process of "raising the output voltage when a valid low current signal is detected" is called "the process of raising the output voltage".

[0100] 5. When the digital control unit reads an invalid low current signal, it indicates that the current output power supply voltage is sufficient to allow the internal charging circuit of the headphones to reach full current operation. The initial follow voltage search for the adaptation is completed, and the initialization phase ends.

[0101] Normal charging phase: 1. After entering the normal follow-up charging phase, execute "maintain charging". Waiting polling period T1 The main loop reads the low current signal. The polling period for this stage is T1. Since the normal charging time is relatively long, the polling period T1 is much longer than T0 in the initialization stage. It can generally be set to several seconds or even more than ten seconds to reduce the system's polling overhead.

[0102] 2. If an invalid low current signal is read, it means that the current output power supply voltage is sufficient and the headphone charging circuit can maintain full current charging without adjusting the output voltage of the voltage conversion module.

[0103] 3. If a valid low current signal is read, it means that the charging current has dropped below the threshold and the current output voltage following the charging is insufficient. Further determine whether the current output supply voltage has reached the preset maximum output voltage. If the preset maximum output voltage has not been reached, increase the output supply voltage according to the preset step size, and then return to step 1 of this stage to continue the loop detection.

[0104] 4. If the current output power supply voltage has reached the preset maximum output voltage, the process will jump to the final stage.

[0105] Final stage: The control voltage conversion module maintains the preset maximum output voltage continuously to charge the headphones until the charging process is complete.

[0106] It should be noted that in this application, the aforementioned preset threshold current, preset maximum output voltage, and preset minimum output voltage are all configurable parameters. The values ​​of each parameter need to be reasonably set in conjunction with the rated parameters of the TWS earphone's battery and charging circuit. The selection criteria and exemplary values ​​for each parameter are as follows: The preset threshold current is determined by the earphone's nominal maximum charging current. Currently, the maximum charging current of most TWS earphones on the market is generally between tens of milliamps and one or two hundred milliamps. This preset threshold current needs to be less than the earphone's maximum charging current. As a preferred implementation, the preset threshold current can be set to 60% of the earphone's maximum charging current. 70%.

[0107] The preset maximum output voltage needs to be higher than the full-charge voltage of the earphone's lithium battery. TWS earphones generally use lithium batteries, and the common full-charge voltages of lithium batteries include 4.2V, 4.35V, and 4.4V, which are determined by the earphone manufacturer based on the battery specifications used. The preset maximum output voltage of the charging case management chip generally needs to be at least 400mV higher than the full-charge voltage of the earphone battery to ensure that the charging circuit has a sufficient voltage difference.

[0108] For the preset minimum output voltage, the voltage of a lithium battery after deep discharge is generally not lower than 3.2V. As an example, the preset minimum output voltage is set to 3.6V in this solution.

[0109] The preset step size can be determined based on the voltage difference between the preset maximum output voltage and the preset minimum output voltage, as well as the desired total number of voltage adjustment levels. For example, if the digital control unit outputs a 5-bit control signal to control the voltage conversion module, it can provide a total of 32 voltage levels. When the preset minimum output voltage is 3.6V and the preset maximum output voltage is 5.15V, the corresponding preset step size is 50mV.

[0110] It should be noted that the preset step size is generally determined during the chip design phase and cannot be modified by the user after the chip leaves the factory; for chips using Buck... In voltage conversion modules based on Boost or Boost switching converter architectures, the voltage regulation step size is mostly determined by analog circuitry and is a fixed value, making it difficult to change via OTP or fuse adjustment. While a few solutions offer a configurable preset step size, this significantly increases circuit size and cost, and is therefore rarely used in practical products.

[0111] The chip offers a wide range of adjustable parameters, such as preset threshold current, preset maximum output voltage, and preset minimum output voltage, allowing headphone designers to configure and select settings according to their product specifications. For example, the chip's hardware design allows for an adjustable output voltage range of 3.6V. 5.1V, headphone manufacturers can choose 3.8V from it according to the actual needs of their products. The operating range is 4.6V, while the voltage adjustment step size remains unchanged from the chip's inherent configuration.

[0112] The voltage follower charging control method of this application has been described above in conjunction with two implementation processes. It should be noted that the voltage follower charging control method of this application is not limited to the two specific processes described above.

[0113] For example, Figure 7 In the corresponding implementation process, the initialization phase starts from the preset minimum output voltage and searches for the initial follower voltage using a step-by-step enumeration method, which has limited initialization search efficiency. As an optional improvement, a binary search and successive approximation algorithm can also be used to complete the search for the initialization voltage; alternatively, the initialization starting point can be set to the preset maximum output voltage, and then adjusted downwards to obtain a suitable initial follower voltage.

[0114] In summary, as long as the solution follows the core control concept of this application: sampling the headphone charging current and comparing it with a preset threshold current, and dynamically adjusting the output power supply voltage of the voltage conversion module based on the current comparison result to achieve voltage-following charging, it falls within the protection scope of this application.

[0115] This application also discloses a chip (charging case management chip), including a battery pin, a power pin, an output pin, a ground pin, and a voltage conversion module, a load switch / current detection module, and a comparator module from the earphone charging circuit provided in any of the above embodiments. The battery pin is electrically connected to the input terminal of the voltage conversion module, the power pin is electrically connected to the output terminal of the voltage conversion module and the input terminal of the load switch / current detection module, and the output pin is electrically connected to the output terminal of the load switch / current detection module and the earphone. The chip highly integrates analog functional modules such as the voltage conversion module, the load switch / current detection module, and the comparator module, eliminating the need for external ADC conversion circuits and multi-channel digital transmission lines, greatly simplifying the peripheral circuitry of the chip. Simultaneously, the chip only needs to transmit a single-bit current status signal, significantly reducing the internal digital resource usage and data transmission overhead. This chip is compatible with both on-chip integrated digital control units and external digital control units, and supports both communication initialization and non-communication adaptive initialization charging modes. It has strong versatility and adaptability, and can reduce the number of components, lower hardware costs, and reduce chip area while ensuring voltage following charging accuracy and charging efficiency, thus meeting the design requirements of miniaturization and lightweighting of TWS earphone charging cases.

[0116] This application also discloses an earphone charging case, including a charging case battery and the earphone charging circuit provided in any of the above embodiments; the positive terminal of the charging case battery is electrically connected to the input terminal of the voltage conversion module, and the negative terminal of the charging case battery is grounded. Based on the aforementioned optimized charging circuit architecture, the earphone charging case eliminates the analog-to-digital conversion, multi-bit data processing, and complex transmission lines required by traditional voltage-following schemes, resulting in a simple hardware structure and high operational stability. The earphone charging case can adaptively switch between two initialization charging modes according to the communication status with the earphones. When communication is normal, it quickly matches the earphone battery voltage to complete charging initialization; when communication is abnormal, it achieves adaptive voltage-following charging through autonomous voltage search, effectively avoiding problems such as low charging efficiency and poor loop stability caused by communication interruptions in traditional schemes. During charging, the output voltage can be dynamically adjusted to always maintain a charging voltage slightly higher than the earphone battery voltage, significantly reducing the voltage difference heat loss of the linear charging circuit inside the earphones and significantly improving charging efficiency. At the same time, a maximum voltage clamping mechanism ensures charging safety, effectively improving the overall battery life and charging reliability of TWS earphones.

[0117] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0118] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A headphone charging circuit, characterized in that, It includes a voltage conversion module, a load switch / current detection module, a comparison module, and a digital control module. The voltage conversion module, the load switch / current detection module, and the comparison module are all electrically connected to the digital control module. The load switch / current detection module is electrically connected to both the voltage conversion module and the comparison module. The load switch / current detection module is used for electrical connection with the headphones. The voltage conversion module receives the battery voltage from the earphone charging case and converts the battery voltage into a power supply voltage according to the start signal and voltage setting signal output by the digital control module. The load switch and current detection module is used to transmit the power supply voltage to the earphone according to the switch signal output by the digital control module, and simultaneously collect the charging current of the earphone and output a sampled current to the comparison module. The comparison module is used to compare the sampled current with a preset threshold current output by the digital control module, and output a low current signal when the sampled current is less than the preset threshold current. Upon receiving the low current signal, the digital control module determines the relationship between the current output voltage of the voltage conversion module and the preset maximum output voltage. When the current output voltage equals the preset maximum output voltage, the module controls the voltage conversion module to maintain the preset maximum output voltage and continuously charge the earphones. When the current output voltage is less than the preset maximum output voltage, the module sends a boost adjustment signal to the voltage conversion module to control the supply voltage to increase by a preset step size, thereby achieving voltage-following charging of the earphones.

2. The headphone charging circuit according to claim 1, characterized in that, The digital control module includes a preset option unit and a first digital control unit. The first digital control unit is electrically connected to the preset option unit, the voltage conversion module, the load switch and current detection module, and the comparison module. The voltage conversion module, the load switch and current detection module, the comparison module, the preset option unit, and the first digital control unit are all integrated into the same chip. The preset option unit is used to store the preset threshold current, the preset maximum output voltage, and the preset step size, and transmit the preset threshold current, the preset maximum output voltage, and the preset step size to the first digital control unit; the first digital control unit is used to receive the low current signal, output the start signal and the boost adjustment signal to the voltage conversion module, output the switching signal to the load switch and current detection module, and output the preset threshold current to the comparison module.

3. The headphone charging circuit according to claim 1, characterized in that, The digital control module includes a register array unit and a second digital control unit. The register array unit is electrically connected to the second digital control unit, the voltage conversion module, the load switch and current detection module, and the comparison module, respectively. The voltage conversion module, the load switch and current detection module, the comparison module, and the register array unit are all integrated into the same chip, while the second digital control unit is located outside the chip. The second digital control unit interacts with the register array unit via a communication bus; the register array unit includes a status register and a control register, and the low current signal output by the comparison module is stored in the status register; the second digital control unit reads the low current signal in the status register and writes control instructions to the control register to configure the preset maximum output voltage, the preset threshold current, and the power supply voltage output by the voltage conversion module.

4. The headphone charging circuit according to claim 1, characterized in that, The voltage conversion module includes a BOOST boost circuit or a BUCK-BOOST buck-boost circuit; when the voltage conversion module uses a BOOST boost circuit and the supply voltage is less than the battery voltage, the BOOST boost circuit operates in pass-through mode.

5. The headphone charging circuit according to claim 1, characterized in that, The load switch and current detection module includes a load switch unit and a current detection unit. The load switch unit is electrically connected to the current detection unit, the voltage conversion module, the digital control module, and the earphone, respectively. The current detection unit is electrically connected to the comparison module. The load switch unit is used to turn on according to the switch signal, so that the power supply voltage is transmitted to the earphone; The current detection unit is used to collect the charging current of the earphone and output the sampled current to the comparison module.

6. A method for controlling headphone charging, characterized in that, Applied to the headphone charging circuit according to any one of claims 1-5, and executed by the digital control module in the headphone charging circuit, the method includes: The digital control module establishes communication with the earphone to obtain the battery voltage of the earphone; based on the battery voltage of the earphone, it configures the initial power supply voltage parameters for the voltage conversion module to complete the charging initialization parameter settings. A start signal and a voltage setting signal are output to the voltage conversion module so that the voltage conversion module converts the battery voltage of the earphone charging case into the output power supply voltage according to the configured initial power supply voltage parameters. A switching signal is output to the load switch and current detection module to enable the load switch and current detection module and supply the power supply voltage to the earphone; A preset threshold current is output to the comparison module so that the comparison module can compare the sampled current collected by the load switch and current detection module with the preset threshold current. The comparison module receives a low current signal when the sampling current is less than the preset threshold current, and determines the relationship between the current power supply voltage output by the voltage conversion module and the preset maximum output voltage. When the current output supply voltage is equal to the preset maximum output voltage, the voltage conversion module is controlled to maintain the preset maximum output voltage to continuously charge the earphone; When the current output supply voltage is less than the preset maximum output voltage, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size, so as to realize voltage-following charging of the earphone.

7. The headphone charging control method according to claim 6, characterized in that, When the digital control module fails to establish communication with the earphone, a no-communication initialization process is executed, which includes: Set the initial power supply voltage of the voltage conversion module to a preset minimum output voltage; The low current signal output by the comparison module is read according to the preset polling cycle; If the low current signal is detected, a boost adjustment signal is sent to the voltage conversion module to control the supply voltage to increase by a preset step size, and the output of the comparison module is polled again until the low current signal is no longer detected, thus completing the charging initialization.

8. The headphone charging control method according to claim 7, characterized in that, The preset polling period includes a first polling period and a second polling period. During the charging initialization process, the low current signal is polled and read according to the first polling period. After the charging initialization is completed, the polling period is switched to the second polling period to read the low current signal. The first polling period is shorter than the second polling period.

9. A chip, characterized in that, The device includes a battery pin, a power pin, an output pin, a ground pin, and a voltage conversion module, a load switch / current detection module, and a comparison module as described in any one of claims 1-5 for headphone charging circuits. The battery pin is electrically connected to the input terminal of the voltage conversion module, the power pin is electrically connected to the output terminal of the voltage conversion module and the input terminal of the load switch / current detection module, and the output pin is electrically connected to the output terminal of the load switch / current detection module and the headphone.

10. An earphone charging case, characterized in that, It includes a charging case battery and the headphone charging circuit according to any one of claims 1-5; the positive terminal of the charging case battery is electrically connected to the input terminal of the voltage conversion module, and the negative terminal of the charging case battery is grounded.

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