Constant current control circuit, fast charging chip, fast charging device and constant current control method

Abstract

The embodiment of the invention discloses a constant current control circuit, a fast charging chip, fast charging equipment and a constant current control method, the circuit comprises a current comparison module, a control module and a voltage loop module, the current comparison module is used for outputting a first control signal when the output current of the fast charging equipment is greater than a preset reference current, and the control module is used for outputting a second control signal when the output current of the fast charging equipment is greater than the preset reference current; when the output current is smaller than the reference current, a second control signal is output; the voltage loop module responds to the output voltage and adjusts the feedback voltage to be equal to the reference voltage when the feedback voltage is larger than or smaller than the preset reference voltage; the control module responds to the first control signal or the second signal and correspondingly adjusts the reference voltage or the feedback voltage so that the output current can be kept within the preset current range. According to the embodiment of the invention, the control module is arranged, the reference voltage or the feedback voltage is adjusted according to the output current, and then the output voltage is controlled, so that constant-current output is realized, the design of a current loop can be omitted, and the circuit is simplified.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of fast charging technology, and in particular to a constant current control circuit, a fast charging chip, a fast charging device, and a constant current control method. Background Art

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

[0003] The traditional USB is a commonly used interface with only 4 wires, two power wires and two signal wires. The signal is transmitted serially, and the speed can reach 480Mbps, 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] As mobile devices have increasingly stringent requirements for transmission speed, charging power, and interface size, a new generation of USB interface USB Type-C has emerged. USB Type-C, referred to as Type-C, is a hardware interface specification for the Universal Serial Bus (USB). The highlights of Type-C are its slimmer design, faster transmission speed (up to 40Gbps), and more powerful power transmission (up to 100W). Type-C supports double-sided insertion of the USB interface, solving the global problem of "USB can never be inserted correctly", and can be inserted from the front or back. At the same time, the USB data cable used with it must also be thinner and lighter.

[0005] In order to support higher output power, various fast charging protocols such as PD, QC, AFC, FCP, SCP, UFCS, etc. were subsequently launched. However, under some protocols, the adapter is required to support constant current mode. Currently, it is basically necessary to add a complex constant current loop to achieve the constant current function, which additionally increases the development cost of the protocol chip and the chip peripheral circuit is also more complicated. Summary of the invention

[0006] The main technical problem solved by the embodiments of the present invention is to provide a constant current control circuit, a fast charging device and a constant current control method, which can solve the problem that the power adapter needs to add a complex constant current loop to achieve the constant current function.

[0007] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: to provide a constant current control circuit, applied to a fast charging device, including: a current comparison module, a control module and a voltage loop module, the control module is respectively connected to the current comparison module and the voltage loop module; the current comparison module is used to output a first control signal when the output current of the fast charging device is greater than a preset reference current, and to output a second control signal when the output current is less than the reference current; the voltage loop module generates a feedback signal in response to the output voltage of the fast charging device or the switching power supply, and is used to adjust the feedback voltage to be equal to the reference voltage when the feedback voltage is greater than or less than a preset reference voltage; the control module adjusts the reference voltage or the feedback voltage accordingly in response to the first control signal or the second signal to keep the output current within a preset current range.

[0008] In some embodiments, when the control module receives the first control signal, after a preset delay time, the control module gradually reduces the reference voltage with a preset voltage threshold as a step value until the output current is less than the reference current; when the control module receives the second control signal, after a preset delay time, the control module gradually increases the reference voltage with the voltage threshold as a step value until the output current is greater than the reference current or the reference voltage increases to the initial value.

[0009] In some embodiments, when the control module receives the first control signal, after a preset delay time, the control module gradually increases the injection current or decreases the extraction current with a preset current threshold as a step value to adjust the feedback signal until the output current is less than the reference current; when the control module receives the second control signal, after a preset delay time, the control module reduces the injection current or increases the extraction current with a preset current threshold as a step value to adjust the feedback signal until the output current is greater than the reference current.

[0010] In some embodiments, the fast charging device includes a current acquisition module, the current comparison module includes an operational amplifier U1 and an operational amplifier U2, the non-inverting input terminal and the inverting input terminal of the operational amplifier U1 are respectively connected to the current acquisition module, the output terminal of the operational amplifier U1 is connected to the non-inverting input terminal of the operational amplifier U2, the inverting input terminal of the operational amplifier U2 receives the reference current, and the output terminal of the operational amplifier U2 is connected to the control module.

[0011] In some embodiments, the charging device includes a power input module and a voltage feedback module, the voltage loop module includes an operational amplifier U3, a resistor R1, a resistor R2 and a switch tube M1, the non-inverting input terminal of the operational amplifier U3 is respectively connected to the voltage feedback module, the second end of the resistor R1 and the first end of the resistor R2, the first end of the resistor R1 is connected to the power input module, and the second end of the resistor R2 is grounded; the inverting input terminal of the operational amplifier U3 is used to receive the reference voltage, the output terminal of the operational amplifier U3 is connected to the gate of the switch tube M1, the drain of the switch tube M1 is connected to the voltage feedback module, and the source of the switch tube M1 is grounded; the output terminal of the control module is connected to the non-inverting input terminal or the reverse input terminal of the operational amplifier U3.

[0012] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: to provide a fast charging chip, including: the constant current control circuit as described above.

[0013] To solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: to provide a charging device, including: a power input module; a current sampling module; a voltage feedback module; and the fast charging chip as described above; the power input module is respectively connected to an external power supply, the current sampling module, the voltage feedback module and the fast charging chip, and the fast charging chip is also respectively connected to the current sampling module and the voltage feedback module.

[0014] To solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: to provide a constant current control method, applied to the control module in the constant current control circuit as described above, including: receiving a control signal: delaying a preset delay time; according to the control signal, adjusting the reference voltage or feedback voltage accordingly to keep the output current within a preset current range.

[0015] In some embodiments, the reference voltage is adjusted so that the output current is maintained within a preset current range, including: determining whether the received signal is a first control signal or a second control signal; if the received signal is the first control signal, gradually reducing the reference voltage with a preset voltage threshold as a step value until the output current is less than the reference current; if the received signal is the second control signal, gradually increasing the reference voltage with the voltage threshold as a step value until the output current is greater than the reference current or the reference voltage increases to the initial value.

[0016] In some embodiments, the feedback voltage is adjusted so that the output current is maintained within a preset current range, including: determining whether the received signal is a first control signal or a second control signal; if the received signal is the first control signal, then using a preset current threshold as a step value, gradually increasing the injection current or decreasing the extraction current to adjust the feedback voltage until the output current is less than the reference current; if the received signal is the second control signal, then using a preset current threshold as a step value, gradually decreasing the injection current or increasing the extraction current to adjust the feedback voltage until the output current is greater than the reference current.

[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 achieve constant current output by setting a control module to adjust the reference voltage or feedback voltage according to the output current, thereby controlling the output voltage. This can eliminate the need for current loop design, simplify the circuit structure, reduce the number of chip pins, reduce chip development costs and packaging costs, and reduce peripheral devices in the chip application circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a circuit structure of a fast charging protocol chip;

[0019] Figure 2 It is a structural schematic diagram of a constant current control circuit provided by an embodiment of the present invention;

[0020] Figure 3 is a circuit structure diagram of a constant current control circuit provided in an embodiment of the present invention;

[0021] Figure 4 is a circuit structure diagram of another constant current control circuit provided in an embodiment of the present invention;

[0022] Figure 5 is a schematic structural diagram of a charging device provided by an embodiment of the present invention;

[0023] Figure 6 It is a flow chart of a constant current control method provided by an embodiment of the present invention;

[0024] Figure 7 yes Figure 6 A schematic diagram of a sub-process of step S300 in the constant current control method shown;

[0025] Figure 8 yes Figure 6 Another sub-process diagram of step S300 in the constant current control method is shown. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" and the like used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, 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 on the present application. In addition, the terms "first", "second", "third" and the like are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0028] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0029] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0030] Existing technologies mainly achieve the function of constant current charging by setting a current loop. Generally, the fast charging protocol chip has two control loops, namely the voltage loop and the current loop. The control loop of the fast charging protocol chip is used to adjust the AC / DC power supply or DC / DC power supply to achieve constant voltage and constant current control. Figure 1 The circuit structure of a fast charging protocol chip is shown, taking the loop control of an AC / DC power supply as an example, wherein a transformer T1, a diode D2 and a capacitor C1 constitute a power module for converting the input voltage of an external power supply into an output voltage; the resistor Rs is a sampling resistor, which is arranged between the power module and the subsequent load and is used to collect the output current of the power supply.

[0031] When the collected output current does not exceed the reference current IREF, the voltage loop takes effect, the power adapter works in constant voltage mode, and outputs a constant voltage to charge the subsequent load; when the collected output current exceeds the reference current IREF, the current loop takes effect, the power adapter works in constant current mode, and outputs a constant current to charge the subsequent load.

[0032] In order to realize constant current power supply, the above circuit structure needs to set up a complex current loop, which will undoubtedly increase the hardware cost. In addition, after setting up the current loop, external current compensation needs to be set up, which requires an additional current feedback pin IFB, that is, the integrated fast charging protocol chip needs to add a pin, and two peripheral devices need to be added in the application, namely Figure 1 The resistor R5 and capacitor C3 shown in the figure further complicate the peripheral circuit; if internal compensation is used, the resistor R5 and capacitor C3 need to be integrated into the fast charging protocol chip, which will also increase the hardware cost and packaging cost of the chip.

[0033] To solve the above problems, the present invention provides a constant current control circuit, the structural diagram of which is shown in FIG. Figure 2 As shown, the constant current control circuit includes a current comparison module 110 , a control module 120 and a voltage loop module 130 .

[0034] The first input end of the control module 120 is connected to the output end of the current comparison module 110, the second input end of the control module 120 is connected to the output end of the voltage feedback module 230 of the fast charging device, and the output end of the control module 120 is connected to the input end of the voltage loop module 130; the input end of the current comparison module 110 is connected to the output end of the current sampling module 220 of the fast charging device, the input end of the current sampling module 220 is connected to the output end of the power input module 210, and the output end of the power input module 210 is connected to the input end of the voltage feedback module 230 and the power input end of the voltage loop module 130.

[0035] The current comparison module 110 is used to output a first control signal when the output current of the fast charging device, that is, the output current collected by the current sampling module 220, is greater than a preset reference current, and to output a second control signal when the output current is less than the reference current.

[0036] As an example but not limitation, the first control signal is a high-level voltage signal, and the second control signal is a low-level voltage signal.

[0037] It should be noted that the reference current may be a preset fixed value, or may be an adjustable value dynamically adjusted by the control module according to preset conditions.

[0038] The voltage loop module 130 generates a feedback signal in response to the output voltage of the fast charging device or the switching power supply, and is used to adjust the feedback voltage to be equal to the reference voltage when the feedback voltage, that is, the voltage collected by the voltage feedback module 230, is greater than or less than the initial value of the preset reference voltage.

[0039] It should be noted that the regulation of the feedback voltage is actually the regulation of the output voltage. During the regulation of the output voltage, the output voltage is in a state of continuous fluctuation. Even if the output voltage is adjusted to be equal to the reference voltage, the output voltage may become larger or smaller at the next moment, and thus not equal to the reference voltage. Therefore, the voltage loop module 130 continuously regulates the output voltage, with the aim of making the output voltage approach the reference voltage, or in other words, making the output voltage fluctuate around the reference voltage.

[0040] The control module 120 adjusts the reference voltage or the feedback voltage accordingly in response to the first control signal or the second signal, so as to keep the output current within a preset current range.

[0041] In some embodiments of the present application, when the control module receives a first control signal, after a preset delay time, the control module gradually reduces the reference voltage with a preset voltage threshold as a step value until the output current is less than the reference current; when the control module receives a second control signal, after a preset delay time, the control module gradually increases the reference voltage with a voltage threshold as a step value until the output current is greater than the reference current or the reference voltage increases to an initial value.

[0042] In other embodiments of the present application, when the control module receives a first control signal, after a preset delay time, the control module gradually increases the injection current or decreases the extraction current with a preset current threshold as a step value to adjust the feedback voltage until the output current is less than a reference current; when the control module receives a second control signal, after a preset delay time, the control module gradually decreases the injection current or increases the extraction current with a preset current threshold as a step value to adjust the feedback voltage until the output current is greater than the reference current.

[0043] When the output voltage decreases, the output current will decrease accordingly, so the output voltage can be adjusted to keep the output current within a current range. It should be noted that after adjusting the output current to be less than the reference current, the current comparison module will instead output the second control signal, that is, during the constant current control process, the current comparison module will alternately output the first control signal and the second control signal.

[0044] It should be noted that the delay time is set to de-jitter the first control signal or the second control signal to ensure that the first control signal or the second control signal is valid.

[0045] Figure 3 The circuit structure of a constant current control circuit provided by an embodiment of the present invention is shown, wherein the current comparison module 110 includes an operational amplifier U1 and an operational amplifier U2, and the voltage loop module 130 includes an operational amplifier U3, a resistor R1, a resistor R2 and a switch tube M1.

[0046] The non-inverting input terminal of the operational amplifier U1 is connected to the first end of the sampling resistor Rs, and the inverting input terminal of the operational amplifier U1 is respectively connected to the second end of the sampling resistor Rs; the output terminal of the operational amplifier U1 is connected to the non-inverting input terminal of the operational amplifier U2, the inverting input terminal of the operational amplifier U2 receives the reference current IREF, and the output terminal of the operational amplifier U2 is connected to the control module 120.

[0047] The non-inverting input terminal of the operational amplifier U3 is respectively connected to the second end of the capacitor C2, the second end of the resistor R1 and the first end of the resistor R2. The first end of the resistor R1 is connected to the first end of the capacitor C1. The second end of the resistor R2 is grounded.

[0048] The inverting input terminal of the operational amplifier U3 is used to receive the reference voltage VREF, the output terminal of the operational amplifier U3 is connected to the gate of the switch tube M1, the drain of the switch tube M1 is connected to the cathode of the diode D1, and the source of the switch tube M1 is grounded.

[0049] The current acquisition module 220 includes a sampling resistor Rs, a resistor R3, a resistor R4, a diode D1 and a capacitor C2 constitute a voltage feedback module 230, and a transformer T1, a diode D2 and a capacitor C1 constitute a power input module 210. The control module 120 is connected to the reverse input terminal of the operational amplifier U3, and the control module 120 adjusts the reference voltage with a preset voltage threshold.

[0050] A first end of the secondary side of the transformer T1 is connected to an anode of a diode D2, a cathode of the diode D2 is connected to a first end of a capacitor C1 and a first end of a resistor R3, a second end of the secondary side of the transformer T1 and a second end of the capacitor C1 are grounded; a second end of the resistor R3 is connected to an anode of the diode D1, a cathode of the diode D1 is connected to a first end of a resistor R4, and a second end of the resistor R4 is connected to a first end of the capacitor C2.

[0051] Specifically, if the current comparison module outputs the second control signal in the initial state, it means that the current flowing through the sampling resistor Rs is small. At this time, it is a constant voltage control, and the reference voltage VREF=V0, where V0 is the initial value.

[0052] As the current flowing through the sampling resistor Rs increases, when the first control signal is detected, it means that the output current exceeds the reference current IREF and constant current control needs to be implemented; at this time, the reference voltage VREF needs to be gradually reduced, and the Vstep is reduced each time according to the pre-set voltage threshold as the step value until the output current is less than the reference current IREF, which is marked as the current comparison module outputting the second control signal. In this process, when the reference voltage VREF decreases, the corresponding output voltage will also decrease, so the output current will also decrease. When the output voltage decreases to a certain value, the current comparison module switches to outputting the second control signal 0.

[0053] After the current comparison module outputs the second control signal, the reference voltage VREF needs to be gradually increased, with a preset voltage threshold as the step value, and Vstep is increased each time until the current comparison module switches to outputting the first control signal or the reference voltage VREF is adjusted to the initial value V0.

[0054] When in constant current mode control, the current comparison module will alternately output the first control signal and the second control signal to achieve a balanced state according to the load condition.

[0055] Figure 4 The circuit structure of another constant current control circuit provided by an embodiment of the present invention is shown, wherein the current comparison module 110 includes an operational amplifier U1 and an operational amplifier U2, and the voltage loop module 130 includes an operational amplifier U3, a resistor R1, a resistor R2 and a switch tube M1.

[0056] The non-inverting input terminal of the operational amplifier U1 is connected to the first end of the sampling resistor Rs, and the inverting input terminal of the operational amplifier U1 is respectively connected to the second end of the sampling resistor Rs; the output terminal of the operational amplifier U1 is connected to the non-inverting input terminal of the operational amplifier U2, the inverting input terminal of the operational amplifier U2 receives the reference current IREF, and the output terminal of the operational amplifier U2 is connected to the control module 120.

[0057] The non-inverting input terminal of the operational amplifier U3 is respectively connected to the second end of the capacitor C2, the second end of the resistor R1 and the first end of the resistor R2. The first end of the resistor R1 is connected to the first end of the capacitor C1. The second end of the resistor R2 is grounded.

[0058] The inverting input terminal of the operational amplifier U3 is used to receive the reference voltage VREF, the output terminal of the operational amplifier U3 is connected to the gate of the switch tube M1, the drain of the switch tube M1 is connected to the cathode of the diode D1, and the source of the switch tube M1 is grounded.

[0059] The current acquisition module 220 includes a sampling resistor Rs, a resistor R3, a resistor R4, a diode D1 and a capacitor C2 constitute a voltage feedback module 230, and a transformer T1, a diode D2 and a capacitor C1 constitute a power input module 210. The control module 120 is connected to the same-direction input terminal of the operational amplifier U3, and the control module 120 adjusts the feedback signal with a preset voltage threshold.

[0060] A first end of the secondary side of the transformer T1 is connected to an anode of a diode D2, a cathode of the diode D2 is connected to a first end of a capacitor C1 and a first end of a resistor R3, a second end of the secondary side of the transformer T1 and a second end of the capacitor C1 are grounded; a second end of the resistor R3 is connected to an anode of the diode D1, a cathode of the diode D1 is connected to a first end of a resistor R4, and a second end of the resistor R4 is connected to a first end of the capacitor C2.

[0061] Specifically, if the current comparison module outputs the second control signal in the initial state, it means that the current flowing through the sampling resistor Rs is small. At this time, it is a constant voltage control, and the reference voltage VREF=V0, where V0 is the initial value.

[0062] As the current flowing through the sampling resistor Rs increases, when the first control signal is detected, it means that the output current exceeds the reference current IREF, and constant current control needs to be implemented; at this time, it is necessary to gradually increase the current injection or decrease the current extraction of the feedback voltage VFB, and increase Istep each time according to the pre-set current threshold as the step value until the output current is less than the reference current IREF, which indicates that the current comparison module outputs the second control signal. In this process, when the current injection or extraction of the feedback voltage VFB is increased, the corresponding output voltage will also decrease, so the output current will also decrease. When the output voltage decreases to a certain value, the current comparison module switches to outputting the second control signal 0.

[0063] After the current comparison module outputs the second control signal, it is necessary to gradually reduce the current input or increase the current extraction of the feedback voltage VFB, and reduce Istep each time according to the preset current threshold as the step value until the current comparison module switches to outputting the first control signal.

[0064] When in constant current mode control, the current comparison module will alternately output the first control signal and the second control signal to achieve a balanced state according to the load condition.

[0065] Different from the prior art, the implementation mode of the present invention realizes constant current output by setting a control module to adjust the reference voltage or feedback voltage according to the output current, thereby controlling the output voltage. This can eliminate the design of the current loop, simplify the circuit structure, reduce the number of chip pins, reduce the chip development cost and packaging cost, and reduce the peripheral devices of the chip application circuit.

[0066] Based on the constant current control circuit provided in the above embodiment, the embodiment of the present invention further provides a fast charging chip, which includes the constant current control circuit described in the above embodiment.

[0067] Based on the fast charging chip provided in the above embodiment, the embodiment of the present invention also provides a fast charging device, and the result schematic diagram is as follows Figure 5 As shown, the fast charging device includes a power input module 210, a current sampling module 220, a voltage feedback module 230 and the fast charging chip 300 as described in the previous embodiment.

[0068] The output end of the power input module 210 is respectively connected to the input end of the current sampling module 220, the input end of the voltage feedback module 230 and the power input end of the fast charging chip 300, the first signal input end of the fast charging chip 300 is connected to the output end of the current sampling module 220, and the first signal input end of the fast charging chip 300 is connected to the output end of the voltage feedback module 230.

[0069] Based on the constant current control circuit provided in the above embodiment, the embodiment of the present invention provides a constant current control method, which is applied to the control module of the constant current control circuit, and its flow chart is as follows: Figure 6 As shown, the method specifically comprises the following steps:

[0070] Step S100: receiving a control signal.

[0071] In the embodiment of the present application, the control signal includes a first control signal and a second control signal.

[0072] Step S200: delay for a preset delay time.

[0073] It should be noted that the delay time is set to de-jitter the first control signal or the second control signal to ensure that the first control signal or the second control signal is valid. Only when the first control signal or the second control signal is stable for a preset time can the control signal be considered valid.

[0074] Step S300: According to the control signal, the reference voltage or the feedback signal is adjusted accordingly to keep the output current within a preset current range.

[0075] In some embodiments of the present application, step S300 specifically includes the following steps, and its flowchart is as follows: Figure 7 As shown:

[0076] Step S310: Determine whether the received signal is the first control signal or the second control signal.

[0077] If the received signal is the first control signal, step S320 is executed; if the received signal is the second control signal, step S330 is executed.

[0078] Step S320: using the preset voltage threshold as a step value, gradually reducing the reference voltage until the output current is less than the reference current.

[0079] Step S330: using the voltage threshold as a step value, gradually increasing the reference voltage until the output current is greater than the reference current or the reference voltage increases to an initial value.

[0080] In other embodiments of the present application, step S300 specifically includes the following steps, and its flowchart is as follows: Figure 8 As shown:

[0081] Step S310: Determine whether the received signal is the first control signal or the second control signal.

[0082] If the received signal is the first control signal, step S320 is executed; if the received signal is the second control signal, step S330 is executed.

[0083] Step S320: using the preset current threshold as a step value, gradually increasing the sink current or decreasing the draw current to adjust the feedback voltage until the output current is less than the reference current.

[0084] Step S330: using the preset current threshold as a step value, gradually reducing the sinking current or increasing the draining current to adjust the feedback voltage until the output current is greater than the reference current.

[0085] Different from the prior art, the implementation of the present invention adjusts the reference voltage or feedback voltage according to the output current, and then controls the output voltage, thereby achieving constant current output, which can avoid the design of the current loop and simplify the control logic.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A constant current control circuit, applied to a fast charging device or a switching power supply, characterized in that: include: A current comparison module, a control module and a voltage loop module, wherein the control module is connected to the current comparison module and the voltage loop module respectively; The current comparison module is used to output a first control signal when the output current of the fast charging device is greater than a preset reference current, and to output a second control signal when the output current is less than the reference current; The voltage loop module generates a feedback voltage in response to the output voltage of the fast charging device or the switching power supply, and is used to adjust the feedback voltage to be equal to the reference voltage when the feedback voltage is greater than or less than a preset reference voltage; The control module adjusts the reference voltage or the feedback voltage accordingly in response to the first control signal or the second signal, so as to keep the output current within a preset current range.

2. The circuit according to claim 1, characterized in that After the control module receives the first control signal and a preset delay time has passed, the control module gradually reduces the reference voltage by taking a preset voltage threshold as a step value until the output current is less than the reference current; After the control module receives the second control signal and a preset delay time has passed, the control module gradually increases the reference voltage with the voltage threshold as a step value until the output current is greater than the reference current or the reference voltage increases to the initial value.

3. The circuit according to claim 1, characterized in that After the control module receives the first control signal and a preset delay time has passed, the control module gradually increases the sink current or decreases the draw current with a preset current threshold as a step value to adjust the feedback voltage until the output current is less than the reference current; After the control module receives the second control signal and a preset delay time has passed, the control module gradually reduces the injection current or increases the extraction current with a preset current threshold as a step value to adjust the feedback voltage until the output current is greater than the reference current.

4. The circuit according to claim 1, wherein the fast charging device comprises a current acquisition module, characterized in that: The current comparison module includes an operational amplifier U1 and an operational amplifier U2. The non-inverting input terminal and the inverting input terminal of the operational amplifier U1 are respectively connected to the current acquisition module, the output terminal of the operational amplifier U1 is connected to the non-inverting input terminal of the operational amplifier U2, the inverting input terminal of the operational amplifier U2 receives the reference current, and the output terminal of the operational amplifier U2 is connected to the control module.

5. The circuit according to claim 1, wherein the charging device comprises a power input module and a voltage feedback module, wherein: The voltage loop module includes an operational amplifier U3, a resistor R1, a resistor R2 and a switch tube M1. The non-inverting input terminal of the operational amplifier U3 is respectively connected to the voltage feedback module, the second end of the resistor R1 and the first end of the resistor R2, the first end of the resistor R1 is connected to the power input module, and the second end of the resistor R2 is grounded; The inverting input terminal of the operational amplifier U3 is used to receive the reference voltage, the output terminal of the operational amplifier U3 is connected to the gate of the switch tube M1, the drain of the switch tube M1 is connected to the voltage feedback module, and the source of the switch tube M1 is grounded; The control module is connected to the non-inverting input terminal or the inverting input terminal of the operational amplifier U3.

6. A fast charging chip, characterized in that: include: A constant current control circuit as described in any one of claims 1 to 5.

7. A charging device, characterized in that: include: Power input module; Current sampling module; Voltage feedback module; And the fast charging chip as claimed in claim 6; The power input module is respectively connected to an external power supply, the current sampling module, the voltage feedback module and the fast charging chip, and the fast charging chip is also respectively connected to the current sampling module and the voltage feedback module.

8. A constant current control method, applied to a control module in a constant current control circuit as claimed in any one of claims 1 to 5, characterized in that: include: Receive control signal: Delay the preset delay time; According to the control signal, the reference voltage or the feedback voltage is adjusted accordingly to keep the output current within a preset current range.

9. The method according to claim 8, characterized in that By adjusting the reference voltage, the output current is kept within a preset current range, including: Determining whether the received signal is a first control signal or a second control signal; If the received signal is the first control signal, the reference voltage is gradually reduced with a preset voltage threshold as a step value until the output current is less than the reference current; If the received signal is the second control signal, the reference voltage is gradually increased with the voltage threshold as a step value until the output current is greater than the reference current or the reference voltage increases to the initial value.

10. The method according to claim 8, characterized in that By adjusting the feedback voltage, the output current is kept within a preset current range, including: Determining whether the received signal is a first control signal or a second control signal; If the received signal is the first control signal, the sink current is gradually increased or the draw current is gradually decreased with a preset current threshold as a step value, so as to adjust the feedback voltage until the output current is less than the reference current; If the received signal is the second control signal, the input current is gradually reduced or the draw current is gradually increased with the preset current threshold as the step value, so as to adjust the feedback voltage until the output current is greater than the reference current.

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