Sampling circuit, fast charging chip and sampling control method thereof

Abstract

The embodiment of the invention discloses a sampling circuit, a fast charging chip and a sampling control method thereof, and the circuit comprises a current conversion module which is used for converting a charging current outputted by a current sampling module into a sampling voltage, and is used for comparing the sampling voltage with a conversion voltage corresponding to a preset reference current, the current comparison module is used for outputting a first detection signal, the voltage division module is used for outputting a feedback voltage in response to a charging voltage, the voltage comparison module is used for comparing the feedback voltage with a preset first reference voltage and outputting a second detection signal, and the voltage comparison module is used for adjusting a reference current and the first reference voltage. And the computing control module is used for calculating charging current and charging voltage according to the states of the first detection signal and the second detection signal. According to the embodiment of the invention, the method can avoid the use of an ADC circuit, reduces the development cost, and shortens the development time.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of electronic technologies, and in particular, to a sampling circuit, a fast charging chip, and a sampling control method thereof. Background Art

[0002] Universal Serial Bus (USB) is a serial bus standard for connecting computer systems to external devices, and also a technical specification for an input / output interface. It is widely used in information communication products such as personal computers and mobile devices, and has been extended to other related fields such as photographic equipment, digital TVs (set-top boxes), and game consoles.

[0003] Traditional USB is a commonly used interface. It has only 4 wires, two power lines and two signal lines. The signals are transmitted serially, and the speed can reach 480 Mbps, which can meet various industrial and civilian needs. At the same time, the maximum output voltage and current of the traditional USB interface are: 5V / 1.5A.

[0004] With the increasingly stringent requirements of mobile devices for transmission rate, charging power, and interface size, the new generation of USB interface, USB Type-C, has emerged. USB Type-C, abbreviated as Type-C, is a hardware interface specification for the Universal Serial Bus (USB). The highlights of the new version of the interface are a thinner design, faster transmission speed (up to 40 Gbps), and more powerful power transmission (up to 100W). Type-C supports double-sided insertion of the USB interface, officially solving the worldwide problem of "USB is always inserted inaccurately", and it can be inserted casually on either side. At the same time, the USB data cable used in conjunction with it must also be thinner and more portable.

[0005] In order to support higher output power, various fast charging protocols, such as PD, QC, AFC, FCP, SCP, UFCS, etc., have been subsequently introduced. However, under some protocols, such as PPS, SCP, UFCS, etc., the adapter is required to report the current charging voltage and current. Existing technical solutions mainly use an ADC circuit to sample the voltage and current. An ADC circuit and a channel selection circuit need to be designed. The ADC converts the charging voltage and current into digital signals and transmits them to the digital circuit for analysis to obtain the voltage and current values. The complex ADC circuit inevitably increases the development time and development cost. Summary of the Invention

[0006] The main technical problem to be solved by the embodiments of the present invention is to provide a sampling circuit, a fast charging chip, and a sampling control method thereof, which can solve some problems existing in the current and voltage sampling of existing fast charging chips.

[0007] To solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: to provide a sampling circuit, which is applied to a fast charging device and includes: a current conversion module, the current conversion module is connected to the current sampling module of the fast charging device, and the current conversion module is configured to convert the charging current output by the current sampling module into a sampling voltage; a current comparison module, the current comparison module is connected to the current conversion module, and the current comparison module is configured to compare the sampling voltage with the conversion voltage corresponding to a preset reference current, and combine a constant current detection circuit to output a first detection signal; a voltage division module, the voltage division module is configured to output a feedback voltage in response to the charging voltage; a voltage comparison module, the voltage comparison module is connected to the voltage division module, and the voltage comparison module is configured to compare the feedback voltage with a preset first reference voltage and output a second detection signal; an arithmetic control module, the arithmetic control module is connected to the current comparison module and the voltage comparison module, and the arithmetic control module is used to adjust the reference current and the first reference voltage, and calculate the charging current and the charging voltage according to the states of the first detection signal and the second detection signal.

[0008] In some embodiments, the current comparison module is configured to output the first detection signal with a high level when the sampling voltage is higher than the conversion voltage; and output the first detection signal with a low level when the sampling voltage is lower than the conversion voltage.

[0009] In some embodiments, the voltage comparison module is configured to output the second detection signal with a low level when the feedback voltage is higher than the reference voltage; and output the second detection signal with a high level when the feedback voltage is lower than the reference voltage.

[0010] In some embodiments, when the first detection signal is at a low level, the arithmetic control module decreases the reference current to the first detection signal being at a high level according to a preset current step value, and calculates the charging current according to the reference current at this time; when the first detection signal is at a high level, the arithmetic control module calculates the charging current according to the reference current.

[0011] In some embodiments, when the first detection signal is at a low level, the operation control module calculates the charging voltage based on the second reference voltage; the first reference voltage is the product of the second reference voltage and a preset constant; when the first detection signal is at a high level and the second detection signal is at a high level, the operation control module decreases the second reference voltage by a preset voltage step value until the second detection signal is at a low level, and calculates the charging current based on the second reference voltage at this time; when the first detection signal is at a high level and the second detection signal is at a low level, the operation control module increases the second reference voltage by a preset voltage step value until the second detection signal is at a high level, and calculates the charging current based on the second reference voltage at this time.

[0012] To solve the above technical problem, another technical solution adopted in the embodiments of the present invention is: to provide a fast charging chip, including: a sampling circuit as described above.

[0013] To solve the above technical problem, another technical solution adopted in the embodiments of the present invention is: to provide a sampling control method, applied to the sampling circuit as described above, including: obtaining a charging current and converting the charging current into a sampling voltage; comparing the sampling voltage with a conversion voltage and outputting a first detection signal; the conversion voltage is obtained from a preset reference current; after a first preset time, determining whether the first detection signal is at a high level; if not, adjusting the reference current by a preset current step value until the first detection signal is at a high level; calculating the charging current based on the reference current at this time, and restoring the reference current to an initial current value.

[0014] In some embodiments, the sampling control method further includes: obtaining a charging voltage and outputting a feedback voltage according to a preset voltage division coefficient; comparing the feedback voltage with a preset first reference voltage and outputting a second detection signal; the first reference voltage is the product of a preset second reference voltage and a preset constant; after a first preset time, determining whether the first detection signal is at a high level; if so, calculating the charging voltage based on the second reference voltage at this time; if the first detection signal is at a low level, adjusting the second reference voltage by a preset voltage step value until the second detection signal changes; calculating the charging voltage based on the second reference voltage at this time, and restoring the second reference voltage to an initial voltage value.

[0015] In some embodiments, the adjusting the reference current by a preset current step value until the first detection signal is at a high level includes: decreasing the reference current by a preset current step value until the first detection signal jumps to a high level.

[0016] In some embodiments, adjusting the second reference voltage according to a preset voltage step value until the second detection signal jumps includes: after a second preset time, determining whether the second detection signal is at a high level; if so, reducing the second reference voltage according to the voltage step value until the second detection signal is at a low level; if not, increasing the second reference voltage according to the voltage step value until the second detection signal is at a high level.

[0017] The beneficial effects of the embodiments of the present invention are as follows: Different from the prior art, the embodiments of the present invention can avoid the use of an ADC circuit, reduce the development cost and shorten the development time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a sampling circuit provided by an embodiment of the present invention;

[0019] Figure 2 is a schematic circuit diagram of a sampling circuit provided by an embodiment of the present invention;

[0020] Figure 3 is a schematic flowchart of a sampling control method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To facilitate the understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is expressed as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is expressed as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "upper", "lower", "inner", "outer", "bottom", etc. used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0022] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in this specification in the description of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0023] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] The technical solutions in the present application will be described below in conjunction with the accompanying drawings.

[0025] The present invention provides a sampling circuit, and its structural schematic diagram is as Figure 1 shown. The sampling circuit includes a current conversion module 110, a current comparison module 120, a voltage division module 130, a voltage comparison module 140, and an operation control module 150.

[0026] Among them, first, the current conversion module 110 is connected to the current sampling module 210 of the fast charging device. The current sampling module 210 is used to collect the charging current signal, and the current conversion module 110 converts the charging current into a corresponding sampling voltage.

[0027] The current comparison module 120 is connected to the current conversion module 110. The current comparison module 120 is used to compare the sampling voltage with the conversion voltage corresponding to the preset reference current and output a corresponding first detection signal. Specifically, when the charging current is greater than the reference current, that is, the charging current is constant current at this time, the sampling voltage is higher than the conversion voltage, and the current comparison module 120 outputs a first detection signal with a high level; conversely, when the charging current is less than the reference current, that is, the sampling voltage is lower than the conversion voltage, a first detection signal with a low level is output to monitor the change of the charging current in real time.

[0028] The main function of the voltage division module 130 is to perform voltage division processing on the charging voltage. Through the voltage division operation, the feedback voltage is output according to the preset voltage division ratio. At the same time, the voltage comparison module 140 compares the feedback voltage with the preset first reference voltage. When the feedback voltage is higher than the first reference voltage, the voltage comparison module 140 outputs a second detection signal with a low level; when the feedback voltage is lower than the reference voltage, a second detection signal with a high level is output.

[0029] The operation control module 150 is the core control unit of the entire sampling circuit and is connected to the current comparison module 120 and the voltage comparison module 140. The operation control module 150 is responsible for adjusting the reference current and the first reference voltage, and calculating the actual charging current and charging voltage according to the states of the first detection signal and the second detection signal.

[0030] When the first detection signal is at a low level, the operation control module 150 will gradually decrease the reference current according to the preset current step value until the first detection signal becomes high level. At this time, the system calculates the actual charging current according to the current reference current value. When the first detection signal itself is at a high level, that is, it means that the charging current is constant current at this time, the operation control module 150 directly uses the current reference current for calculation.

[0031] For voltage sampling, when the first detection signal is at a low level, the operation control module 150 calculates the charging voltage using the second reference voltage, where the first reference voltage is equal to the product of the second reference voltage and a preset constant. When using the second reference voltage for reference comparison, by introducing the product relationship of the preset constant, a buffer interval can be set for the voltage comparison process, which helps to prevent misjudgment or oscillation phenomena during the voltage comparison process; in addition, by adjusting the magnitude of the preset constant, the trigger threshold of the voltage comparison can be flexibly set, making the voltage sampling and control process have better adaptability and stability.

[0032] Specifically, when the first detection signal is at a high level and the second detection signal is at a high level, the operation control module 150 decreases the second reference voltage according to a preset voltage step value until the second detection signal becomes a low level, and then calculates the charging voltage based on the second reference voltage at this time; when the first detection signal is at a high level and the second detection signal is at a low level, the operation control module 150 increases the second reference voltage according to a preset voltage step value until the second detection signal becomes a high level, and then calculates the charging voltage based on the second reference voltage at this time.

[0033] Figure 2 FIG. is the circuit schematic diagram of the sampling circuit described in the above embodiment, where the current sampling module 210 collects the charging current through the sampling resistor Rs. When the charging current flows through the sampling resistor Rs, a voltage difference will be generated across the sampling resistor Rs, and the voltage difference signal is input to the current conversion module 110 through two ports CS+ and CS-.

[0034] The core of the current conversion module 110 is an operational amplifier U1, and the operational amplifier U1 converts and amplifies the voltage difference across the sampling resistor Rs into a single-ended sampling voltage signal, so that a small current change can be converted into a relatively large and easy-to-process voltage signal.

[0035] The core structure of the current comparison module 120 includes an operational amplifier U2, a current reference IREF, and a constant current detection unit 121. One input terminal of the operational amplifier U2 is connected to the sampling voltage from the current conversion module 110, and the other input terminal is connected to the conversion voltage generated by the reference current IREF.

[0036] When the sampling voltage is higher than the conversion voltage, the current comparison module 120 outputs a first detection signal at a high level (CC_FLAG = 1); when the sampling voltage is lower than the conversion voltage, the current comparison module 120 outputs a first detection signal at a low level (CC_FLAG = 0) to accurately judge the magnitude relationship between the charging current and the reference current.

[0037] The voltage division module 130 consists of a voltage division network composed of resistor R1 and resistor R2. The voltage division network divides the charging voltage VIN according to a specific ratio and outputs the feedback voltage VFB. The purpose of the voltage division design is to convert a potentially high charging voltage into a voltage level suitable for processing by the voltage comparison module 140.

[0038] The core structure of the voltage comparison module 140 includes a comparator U4. One input terminal of the comparator is connected to the feedback voltage VFB from the voltage division module 130, and the other input terminal is connected to a preset first reference voltage (K * VREF), where K is a preset constant and K can take any value less than 1. When the feedback voltage is higher than the reference voltage, the comparator U4 outputs a low-level second detection signal (VIN_DET_FLAG = 0); when the feedback voltage is lower than the reference voltage, it outputs a high-level second detection signal (VIN_DET_FLAG = 1).

[0039] The operation control module 150, as the core control unit of the sampling circuit, is responsible for adjusting the current reference IREF and the second reference voltage VREF, and calculating the charging current and charging voltage according to the states of the first detection signal and the second detection signal.

[0040] According to Figure 2 As shown, the operation control module 150 receives the first detection signal (CC_FLAG) from the current comparison module 120 and the second detection signal (VIN_DET_FLAG) from the voltage comparison module 140. The operation control module 150 processes these signals through an internal digital control circuit (Digital Control) and outputs the adjustment control of the reference current IREF and the second reference voltage VREF.

[0041] The specific control strategy is as follows: when the first detection signal is at a low level (CC_FLAG = 0), the operation control module 150 gradually reduces the reference current IREF according to a preset current step value until the first detection signal becomes high, then calculates the actual charging current based on the reference current at this time, and restores the reference current to the initial current value. When the first detection signal is at a high level (CC_FLAG = 1), it means that the charging current is constant at this time, and the charging current can be directly calculated based on the reference current.

[0042] For voltage control, when the first detection signal is at a low level (CC_FLAG = 0), the operation control module 150 calculates the charging voltage using the second reference voltage VREF, VIN = VREF * (R1 + R2) / R2. In the case where the first detection signal is at a high level (CC_FLAG = 1), the module will accurately calculate the charging voltage by adjusting the second reference voltage according to the state of the second detection signal.

[0043] Specifically, if the first detection signal is at a high level (CC_FLAG = 1), then it is determined whether the second detection signal VIN_DET_FLAG is 1. If the second detection signal VIN_DET_FLAG is 1, the second reference voltage VREF is gradually decreased according to a preset voltage step value. Each time the voltage step value Vstep is decreased, the second reference voltage VREF = VREF - Vstep until the second detection signal VIN_DET_FLAG = 0. If the second detection signal VIN_DET_FLAG is 0, the second reference voltage VREF is gradually increased according to a preset voltage step value. Each time the voltage step value Vstep is increased, the second reference voltage VREF = VREF + Vstep until the second detection signal VIN_DET_FLAG = 1. When the second detection signal VIN_DET_FLAG jumps, the charging voltage is calculated through the second reference voltage VREF at this time, VIN = K * VREF * (R1 + R2) / R2, and the second reference voltage VREF is restored to the initial voltage value.

[0044] It should be noted that when adjusting the second reference voltage VREF, an upper voltage limit value and a lower voltage limit value can be set to cope with abnormal situations caused by too high or too low voltage that may occur during the adjustment of the second reference voltage VREF.

[0045] Different from the traditional ADC sampling scheme, this implementation method avoids the complex ADC circuit design, significantly reduces the development cost and shortens the development cycle.

[0046] Based on the sampling circuit provided by the above implementation method, the present invention also provides a fast charging chip, which includes the sampling circuit provided by the above implementation method.

[0047] Based on the sampling circuit provided by the above implementation method, the present invention also provides a sampling control method, and its flowchart is as Figure 3 shown. The sampling control method specifically includes the following steps:

[0048] Step S110: Obtain the charging current and convert the charging current into a sampling voltage.

[0049] In a specific implementation, the charging current is first collected by the current sampling module 210. As Figure 2 shown, when the charging current flows through the sampling resistor Rs, a voltage difference signal will be generated. The voltage difference signal is input into the operational amplifier U1 in the current conversion module 110 through two ports CS+ and CS-. The operational amplifier U1 converts and amplifies the differential voltage signal into a single-ended sampling voltage signal.

[0050] Step S120: Compare the sampled voltage and the converted voltage, and output a first detection signal.

[0051] As Figure 2 shown, the current comparison module 120 uses the operational amplifier U2 and the constant current detection unit 121 to complete this function. One input terminal of the operational amplifier U2 receives the sampled voltage signal from the current conversion module 110, and the other input terminal is connected to the converted voltage generated by the preset reference current IREF. When the sampled voltage is higher than the converted voltage, the constant current detection unit 121 outputs a first detection signal with a high level; when the sampled voltage is lower than the converted voltage, the constant current detection unit 121 outputs a first detection signal with a low level, so as to accurately judge the magnitude relationship between the charging current and the reference current.

[0052] Step S130: After a first preset time, judge whether the first detection signal is at a high level.

[0053] After receiving the first detection signal, if it is found that the first detection signal changes, a debounce delay of a first preset time needs to be performed on the first detection signal to ensure that the first detection signal is stable and reliable. Then judge whether the first detection signal is at a high level. If so, execute step S150; if not, execute step S140.

[0054] Step S140: Adjust the reference current according to the preset current step value until the first detection signal is at a high level.

[0055] Gradually reduce the reference current IREF according to the preset current step value until the first detection signal becomes at a high level.

[0056] Step S150: Calculate the charging current according to the reference current at this time.

[0057] Based on the gain relationship between the sampling resistor Rs in the circuit and the operational amplifier U1, calculate the charging current according to the reference current at this time, and restore the reference current to the initial current value.

[0058] Step S210: Obtain the charging voltage and output a feedback voltage according to the preset voltage division coefficient.

[0059] As Figure 2 shown, the voltage division module 130 uses the resistors R1 and R2 to form a voltage division network to divide the charging voltage VIN according to a specific ratio and output the feedback voltage VFB.

[0060] Step S220: Compare the feedback voltage with a preset first reference voltage and output a second detection signal.

[0061] The voltage comparison module 140 accomplishes this function using the comparator U4. One input terminal of the comparator U4 receives the feedback voltage VFB from the voltage division module 130, and the other input terminal is connected to a preset first reference voltage. By comparing the feedback voltage VFB with the first reference voltage, the comparator U4 outputs a corresponding second detection signal. Specifically, when the feedback voltage is higher than the reference voltage, a low-level signal is output; when the feedback voltage is lower than the reference voltage, a high-level signal is output.

[0062] Step S230: After a first preset time, determine whether the first detection signal is at a high level.

[0063] After receiving the first detection signal, if it is found that the first detection signal has changed, a debounce delay of a first preset time needs to be performed on the first detection signal to ensure that the first detection signal is stable and reliable. Subsequently, determine whether the first detection signal is at a high level. If so, execute step S240; if not, execute step S250.

[0064] Step S240: Adjust the second reference voltage according to a preset voltage step value until the second detection signal undergoes a jump.

[0065] Adjust the second reference voltage using a preset voltage step value until the second detection signal undergoes a jump.

[0066] Step S250: Calculate the charging voltage based on the second reference voltage at this time.

[0067] Using the finally determined second reference voltage VREF and combining with the parameter relationship of the voltage division network, calculate the actual charging voltage. Specifically, when the first detection signal is at a low level, the charging voltage is calculated using the following formula: VIN = VREF * (R1 + R2) / R2; when the first detection signal is at a high level 1, the formula VIN = KVREF(R1 + R2) / R2 is used, where K is a preset constant. It should be noted that after the voltage calculation is completed, the second reference voltage will be restored to the initial voltage value.

[0068] In some embodiments of the present application, step S250 includes the following steps:

[0069] Step S251: After a second preset time, determine whether the second detection signal is at a high level.

[0070] After receiving the second detection signal, if it is found that the second detection signal has changed, a debounce delay of a second preset time needs to be performed on the second detection signal to ensure that the second detection signal is stable and reliable. Subsequently, determine whether the second detection signal is at a high level. If so, execute step S252; if not, execute step S253.

[0071] Step S252: Decrease the second reference voltage according to the voltage step value until the second detection signal becomes low level.

[0072] Gradually decrease the second reference voltage according to the preset voltage step value. After each adjustment, check the state of the second detection signal until the signal becomes low level. This adjustment process is actually to find a critical point, that is, the position where the feedback voltage just starts to be greater than the reference voltage, and then calculate the charging voltage according to this critical point.

[0073] Step S253: Increase the second reference voltage according to the voltage step value until the second detection signal becomes high level.

[0074] Similarly, gradually increase the second reference voltage using the preset voltage step value. After each adjustment, check the state of the second detection signal until the signal becomes high level. This adjustment process is actually to find a critical point, that is, the position where the feedback voltage just starts to be less than the reference voltage, and then calculate the charging voltage according to this critical point.

[0075] It should be noted that when adjusting the second reference voltage, an upper voltage limit value and a lower voltage limit value can be set to cope with abnormal situations caused by too high or too low voltage that may occur during the adjustment of the second reference voltage.

[0076] Different from the traditional ADC sampling scheme, this implementation method avoids the complex ADC circuit design, significantly reduces the development cost and shortens the development cycle.

[0077] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present application as above. For the sake of brevity, they are not provided in detail; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A sampling circuit, applied to a fast charging device, characterized in that: include: A current conversion module, the current conversion module is connected to the current sampling module of the fast charging device, and the current conversion module is configured to convert the charging current output by the current sampling module into a sampling voltage; A current comparison module, the current comparison module is connected to the current conversion module, the current comparison module is configured to compare the sampled voltage with a conversion voltage corresponding to a preset reference current, and output a first detection signal in combination with a constant current detection unit; A voltage dividing module, wherein the voltage dividing module is configured to output a feedback voltage in response to a charging voltage; A voltage comparison module, the voltage comparison module is connected to the voltage dividing module, and the voltage comparison module is configured to compare the feedback voltage with a preset first reference voltage and output a second detection signal; An operation control module, wherein the operation control module is connected to the current comparison module and the voltage comparison module, and the operation control module is used to adjust the reference current and the first reference voltage, and calculate the charging current and the charging voltage according to the states of the first detection signal and the second detection signal.

2. The circuit according to claim 1, characterized in that The current comparison module is used to output the first detection signal of a high level when the sampling voltage is higher than the conversion voltage; and to output the first detection signal of a low level when the sampling voltage is lower than the conversion voltage.

3. The circuit according to claim 1, characterized in that The voltage comparison module is used to output the second detection signal of a low level when the feedback voltage is higher than the reference voltage; and to output the second detection signal of a high level when the feedback voltage is lower than the reference voltage.

4. The circuit according to claim 1, characterized in that When the first detection signal is at a low level, the operation control module reduces the reference current according to a preset current step value until the first detection signal is at a high level, and calculates the charging current according to the reference current at this time; When the first detection signal is at a high level, the operation control module calculates the charging current according to the reference current.

5. The circuit according to claim 1, characterized in that When the first detection signal is at a low level, the operation control module calculates the charging voltage according to a second reference voltage; the first reference voltage is the product of the second reference voltage and a preset constant; When the first detection signal is at a high level and the second detection signal is at a high level, the operation control module reduces the second reference voltage according to a preset voltage step value until the second detection signal is at a low level, and calculates the charging current according to the second reference voltage at this time; When the first detection signal is at a high level and the second detection signal is at a low level, the operation control module increases the second reference voltage according to a preset voltage step value until the second detection signal is at a high level, and calculates the charging current according to the second reference voltage at this time.

6. A fast charging chip, characterized in that: include: A sampling circuit as claimed in any one of claims 1 to 5.

7. A sampling control method, applied to the sampling circuit according to any one of claims 1 to 5, characterized in that: include: Acquiring a charging current and converting the charging current into a sampling voltage; Comparing the sampled voltage and the converted voltage, and outputting a first detection signal; the converted voltage is obtained by a preset reference current; After a first preset time, determining whether the first detection signal is at a high level; If not, adjusting the reference current according to a preset current step value until the first detection signal is at a high level; The charging current is calculated according to the reference current at this time, and the reference current is restored to an initial current value.

8. The method according to claim 7, characterized in that Also includes: Obtain the charging voltage and output the feedback voltage according to the preset voltage division coefficient; Comparing the feedback voltage with a preset first reference voltage, and outputting a second detection signal; the first reference voltage is the product of a preset second reference voltage and a preset constant; After a first preset time, determining whether the first detection signal is at a high level; If yes, calculating the charging voltage according to the second reference voltage at this time; If the first detection signal is at a low level, adjusting the second reference voltage according to a preset voltage step value until the second detection signal jumps; The charging voltage is calculated according to the second reference voltage at this time, and the second reference voltage is restored to an initial voltage value.

9. The method according to claim 7, characterized in that: The step of adjusting the reference current according to a preset current step value until the first detection signal is at a high level includes: The reference current is reduced according to a preset current step value until the first detection signal jumps to a high level.

10. The method according to claim 8, characterized in that The step of adjusting the second reference voltage according to a preset voltage step value until the second detection signal changes, comprises: After a second preset time, determining whether the second detection signal is at a high level; If yes, reducing the second reference voltage according to the voltage step value until the second detection signal is at a low level; If not, the second reference voltage is increased according to the voltage step value until the second detection signal is at a high level.

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