Feedback control circuit, switching power supply circuit and charger

Abstract

The utility model discloses a feedback control circuit, a switching power supply circuit and a charger. The feedback control circuit comprises a current acquisition circuit, a distance sensing circuit and an error amplification circuit. The first end of the current acquisition circuit is used for being connected with the output end of a current output circuit, the second end of the current acquisition circuit is connected with the first end of the error amplification circuit, and the current acquisition circuit is used for outputting sampling voltage to the error amplification circuit according to the output current of the current output circuit; and the distance sensing circuit is connected with the second end of the error amplifying circuit and is used for outputting reference voltage to the error amplifying circuit according to the sensing distance of the target object. The feedback control circuit can change the output current of the current output circuit according to the sensing distance of the sensed target object so as to adjust the electromagnetic radiation of the current output circuit and prevent the electromagnetic radiation from influencing the target object.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to a feedback control circuit, a switching power supply circuit and a charger. Background Art

[0002] Currently, high-power charging devices and chargers are widely used in people's daily lives, greatly improving the charging efficiency of electronic devices and providing convenience.

[0003] However, high-power charging devices, especially chargers for mobile phones or other devices, are often placed very close to the human body due to their frequent use. Such high-power chargers usually have a higher charging current when charging, so they will inevitably produce higher electromagnetic radiation, which will affect human health to a certain extent. Users will also have concerns about health problems when using them, which brings inconvenience. Utility Model Content

[0004] The embodiments of the utility model provide a feedback control circuit, a switching power supply circuit and a charger to solve the problem that strong electromagnetic radiation during charging of a device affects human health.

[0005] The embodiment of the utility model provides a feedback control circuit, including a current acquisition circuit, a distance sensing circuit and an error amplification circuit;

[0006] The first end of the current acquisition circuit is used to be connected to the output end of the current output circuit, and the second end of the current acquisition circuit is connected to the first end of the error amplifier circuit, and is used to output a sampling voltage to the error amplifier circuit according to the output current of the current output circuit;

[0007] The distance sensing circuit is connected to the second end of the error amplifying circuit and is used to output a reference voltage to the error amplifying circuit according to the sensing distance of the target object;

[0008] The third terminal of the error amplifier circuit is used to connect to the feedback terminal of the current output circuit, and is used to output a feedback current to the current output circuit according to the sampling voltage and the reference voltage.

[0009] Preferably, the distance sensing circuit comprises a sensor module and a voltage output module;

[0010] The sensor module is used to output a sensing signal according to the sensing distance of the target object;

[0011] The voltage output module is connected to the sensor module and the first end of the error amplifier circuit, and is used to output a sampling voltage to the error amplifier circuit according to the sensing signal.

[0012] Preferably, the sensor module comprises a radar detection module;

[0013] The output end of the radar detection module is connected to the voltage output module, and is used to output a first sensing signal to the voltage output module when the sensing distance of the target object is less than a preset distance, or output a second sensing signal to the voltage output module when the sensing distance of the target object is not less than the preset distance;

[0014] a voltage output module, configured to output a first reference voltage to the error amplifying circuit according to the first sensing signal, or to output a second reference voltage to the error amplifying circuit according to the second sensing signal;

[0015] The error amplifier circuit is used to output a first feedback current to the current output circuit according to the first reference voltage and the sampling voltage, or to output a second feedback current to the current output circuit according to the second reference voltage and the sampling voltage.

[0016] Preferably, the voltage output module includes a first voltage dividing unit and a second voltage dividing unit;

[0017] A first end of the first voltage dividing unit is connected to a voltage source, and a second end of the first voltage dividing unit is connected to the error amplifying circuit;

[0018] The second voltage-dividing unit is connected in parallel with the first voltage-dividing unit, and a control end of the second voltage-dividing unit is connected to the sensor module, and is used for being turned on under the control of the first sensing signal, and together with the first voltage-dividing unit, forming a voltage-dividing effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit is the first reference voltage, or being turned off under the control of the second sensing signal, so that the first voltage-dividing unit forms a voltage-dividing effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit is the second reference voltage.

[0019] Preferably, the first voltage dividing unit comprises a first resistor and a second resistor;

[0020] The first resistor and the second resistor are connected in series between the voltage source and the ground, and the error amplifier circuit is connected to a connection node between the first resistor and the second resistor.

[0021] Preferably, the second voltage dividing unit includes a third resistor, a fourth resistor and a control tube;

[0022] The first end of the third resistor is connected to the connection node between the first resistor and the second resistor, and the second end of the third resistor is connected to the first end of the control tube;

[0023] The second end of the control tube is connected to the output end of the radar detection module through the fourth resistor, and the third end of the control tube is grounded, and is used to be turned on under the control of the first sensing signal, or turned off under the control of the second sensing signal.

[0024] Preferably, the second voltage dividing unit further includes a first capacitor;

[0025] The first end of the first capacitor is connected to the second end of the third resistor, and the second end of the first capacitor is connected to the third end of the control tube.

[0026] Preferably, an optical coupler feedback module is further provided between the error amplification circuit and the current output circuit;

[0027] The first end of the optocoupler feedback module is connected to the third end of the error amplifier circuit, and the second end of the optocoupler feedback module is used to be connected to the feedback end of the current output circuit, and is used to output feedback current to the current output circuit under the control of the error amplifier circuit.

[0028] The embodiment of the utility model further provides a switching power supply circuit, comprising a current output circuit and the above-mentioned feedback control circuit;

[0029] The current output circuit includes a primary rectification and filtering module, a primary chip, a transformer module, and a secondary rectification and filtering module;

[0030] The input end of the primary rectifier and filter module is used to connect to the mains circuit, the output end of the primary rectifier and filter module is connected to the primary end of the transformer module, the secondary end of the transformer module is connected to the input end of the secondary rectifier and filter module, and the output end of the secondary rectifier and filter module is used to connect to an external load;

[0031] The primary chip is connected to the primary end of the transformer module and is used to output a PWM signal to the transformer module;

[0032] In the feedback control circuit, the input end of the current acquisition circuit is connected to the negative output end of the secondary rectifier and filter module, and the third end of the error amplifier circuit is connected to the feedback end of the primary chip, which is used to output feedback current to the primary chip, so that the primary chip adjusts the PWM signal according to the feedback current control to adjust the output current of the transformer module.

[0033] An embodiment of the utility model further provides a charger, comprising the above-mentioned switching power supply circuit.

[0034] The feedback control circuit, switching power supply circuit and charger provided by the embodiments of the utility model set a distance sensing circuit in the feedback control circuit to sense the sensing distance to a target object, such as a human body, and output a reference voltage accordingly, so that the operational amplifier performs feedback control on the output current of the current output circuit according to the reference voltage. The output current of the current output circuit can be changed according to the sensing distance of the sensed target object to adjust the electromagnetic radiation of the current output circuit and prevent the electromagnetic radiation from affecting the target object. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a circuit structure diagram of a feedback control circuit in one embodiment of the utility model;

[0037] Figure 2 It is a block diagram of a switching power supply circuit in one embodiment of the utility model.

[0038] In the figure: 1. Current acquisition circuit; 2. Distance sensing circuit; 21. Sensor module; 22. Voltage output module; 221. First voltage divider unit; 222. Second voltage divider unit; 3. Error amplification circuit; 4. Current output circuit; 41. Primary rectifier and filter module; 42. Primary IC; 43. Transformer module; 44. Secondary rectifier and filter module; 5. Optocoupler feedback module. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] It should be understood that the utility model can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and fully convey the scope of the utility model to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0041] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. On the contrary, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0042] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0043] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising" when used in this specification determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0044] In order to thoroughly understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0045] The utility model embodiment provides a feedback control circuit, such as Figure 1 As shown, it includes a current acquisition circuit 1, a distance sensing circuit 2 and an error amplifier circuit 3; the first end of the current acquisition circuit 1 is used to be connected to the output end of the current output circuit 4, and the second end of the current acquisition circuit 1 is connected to the first end of the error amplifier circuit 3, and is used to output a sampling voltage to the error amplifier circuit 3 according to the output current Io of the current output circuit 4; the distance sensing circuit 2 is connected to the second end of the error amplifier circuit 3, and is used to output a reference voltage to the error amplifier circuit 3 according to the sensing distance of the target object; the third end of the error amplifier circuit 3 is used to be connected to the feedback end of the current output circuit 4, and is used to output a feedback current to the current output circuit 4 according to the sampling voltage and the reference voltage.

[0046] As an example, the feedback control circuit is used to provide feedback control for the output current of the current output circuit 4, and includes a current acquisition circuit 1, a distance sensing circuit 2 and an error amplification circuit 3. Figure 2 As shown, the error amplifier circuit 3 may include an operational amplifier U1U1, a first end of the error amplifier circuit 3 is also the non-inverting input end of the operational amplifier U1, a second end of the error amplifier circuit 3 is also the inverting input end of the operational amplifier U1, and a third end of the error amplifier circuit 3 is also the output end of the operational amplifier U1. The first end of the current acquisition circuit 1 is used to connect the output end of the current output circuit 4, and the second end of the current acquisition circuit 1 is connected to the non-inverting input end of the operational amplifier U1 in the error amplifier circuit 3. The distance sensing circuit 2 is connected to the inverting input end of the operational amplifier U1 in the error amplifier circuit 3. In the error amplifier circuit 3, the output end of the operational amplifier U1 is connected to the feedback end of the current output circuit 4.

[0047] During the operation of the circuit, the current acquisition circuit 1 acquires the output current Io of the current output circuit 4, and converts the current into a sampling voltage through a sampling resistor, and inputs it to the non-inverting input terminal of the operational amplifier U1. The distance sensing circuit 2 outputs a reference voltage to the inverting input terminal of the operational amplifier U1 according to the current sensing distance with the target object, such as the human body. For example, when the sensing distance is less than the preset distance, the first reference voltage is output, and when the sensing distance is not less than the preset distance, the second reference voltage is output, wherein the voltage value of the first reference voltage is less than the voltage value of the second reference voltage; or, a positive proportional relationship between the sensing distance and the reference voltage is set, and a corresponding reference voltage is output according to the sensing distance. The operational amplifier U1 compares the reference voltage with the sampling voltage. If the current sampling voltage is different from the reference voltage, the corresponding feedback current is output to the feedback terminal of the current output circuit 4, and the output current Io of the current output circuit 4 is feedback-controlled.

[0048] In this example, by sensing the sensing distance between the target object, such as the human body, a reference voltage is output accordingly, so that the operational amplifier U1 performs feedback control on the output current of the current output circuit 4 according to the reference voltage. The output current of the current output circuit 4 can be changed according to the sensing distance of the sensed target object to adjust the electromagnetic radiation of the current output circuit 4 and prevent the electromagnetic radiation from affecting the target object.

[0049] In one embodiment, the distance sensing circuit 2 includes a sensor module 21 and a voltage output module 22; the sensor module 21 is used to output a sensing signal according to the sensing distance of the target object; the voltage output module 22 is connected to the sensor module 21 and the first end of the error amplification circuit 3, and is used to output a sampling voltage to the error amplification circuit 3 according to the sensing signal.

[0050] As an example, the distance sensing circuit 2 includes a sensor module 21 and a voltage output module 22. The sensor module 21 is connected to the voltage output module 22, and the voltage output module 22 is connected to the inverting input terminal of the operational amplifier U1 in the error amplifier circuit 3. During the operation of the circuit, the sensor module 21 outputs a sensing signal to the voltage output module 22 according to the sensing distance between the sensor module 21 and the target object, and the voltage output module 22 outputs a reference voltage to the inverting input terminal of the operational amplifier U1 according to the sensing signal.

[0051] In another embodiment, the distance sensing circuit 2 may also include a sensor module 21 and an MCU, wherein the sensor module 21 is connected to the MCU, and the MCU is connected to the inverting input terminal of the operational amplifier U1 in the error amplifier circuit 3. During the operation of the circuit, the sensor module 21 outputs a sensing signal to the MCU according to the sensing distance between the sensor module 21 and the target object, and the MCU outputs a reference voltage to the inverting input terminal of the operational amplifier U1 according to the sensing signal.

[0052] In one embodiment, the sensor module 21 includes a radar detection module; the output end of the radar detection module is connected to the voltage output module 22, and is used to output a first sensing signal to the voltage output module 22 when the sensing distance of the target object is less than a preset distance, or, when the sensing distance of the target object is not less than the preset distance, output a second sensing signal to the voltage output module 22; the voltage output module 22 is used to output a first reference voltage to the error amplifier circuit 3 according to the first sensing signal, or, according to the second sensing signal, output a second reference voltage to the error amplifier circuit 3; the error amplifier circuit 3 is used to output a first feedback current to the current output circuit 4 according to the first reference voltage and the sampling voltage, or, according to the second reference voltage and the sampling voltage, output a second feedback current to the current output circuit 4.

[0053] As an example, the sensor module 21 includes a radar detection module. The radar detection module may include a radar sensor, such as an AT60L2AA11-1211 radar sensor. The radar sensor may emit frequency modulated microwaves. When a human body appears within the range of the radar sensor, the microwaves will be scattered and reflected by the human body and transmitted back to the radar sensor. The radar sensor processes and measures the received microwaves, and may obtain the current distance between the human body and the radar sensor, and output a level signal according to the distance. The output end of the radar detection module is connected to the voltage output module 22.

[0054] During the operation of the circuit, when the sensing distance between the target object and the preset distance is less than the preset distance, the radar detection module can output a first sensing signal, such as a high-level signal, to the voltage output module 22. The voltage output module 22 outputs a first reference voltage to the inverting input terminal of the operational amplifier U1 according to the first sensing signal. The operational amplifier U1 outputs a first feedback current to the current output circuit 4 according to the first reference voltage and the sampling voltage. When the sensing distance between the target object and the preset distance is less than the preset distance, the radar detection module can output a second sensing signal, such as a low-level signal, to the voltage output module 22. The voltage output module 22 outputs a second reference voltage to the inverting input terminal of the operational amplifier U1 according to the second sensing signal. The operational amplifier U1 outputs a second feedback current to the current output circuit 4 according to the second reference voltage and the sampling voltage.

[0055] In one embodiment, the voltage output module 22 includes a first voltage divider unit 221 and a second voltage divider unit 222; the first end of the first voltage divider unit 221 is connected to the voltage source, and the second end of the first voltage divider unit 221 is connected to the error amplifier circuit 3; the second voltage divider unit 222 is connected in parallel with the first voltage divider unit 221, and the control end of the second voltage divider unit 222 is connected to the sensor module 21, and is used to be turned on under the control of the first sensing signal, and together with the first voltage divider unit 221, form a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 is the first reference voltage, or, under the control of the second sensing signal, turned off, so that the first voltage divider unit 221 forms a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 is the second reference voltage.

[0056] As an example, the voltage output module 22 includes a first voltage dividing unit 221 and a second voltage dividing unit 222. The first end of the first voltage dividing unit 221 is connected to a +5V voltage source, and the second end of the first voltage dividing unit 221 is connected to the error amplifier circuit 3; the second voltage dividing unit 222 is connected in parallel with the first voltage dividing unit 221, and the control end of the second voltage dividing unit 222 is connected to the sensor module 21.

[0057] When the sensing distance between the sensor module 21 and the target object is less than the preset distance, the sensor module 21 can output a first sensing signal to the second voltage divider unit 222, and the second voltage divider unit 222 can be turned on under the control of the first sensing signal, and together with the first voltage divider unit 221, form a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 can be the first reference voltage; when the sensing distance between the sensor module 21 and the target object is not less than the preset distance, the sensor module 21 can output a second sensing signal to the second voltage divider unit 222, and the second voltage divider unit 222 is turned off under the control of the second sensing signal. At this time, only the first voltage divider unit 221 forms a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 can be the second reference voltage.

[0058] In one embodiment, the first voltage dividing unit 221 includes a first resistor R1 and a second resistor R2; the first resistor R1 and the second resistor R2 are connected in series between a voltage source and ground, and the error amplifier circuit 3 is connected to a connection node between the first resistor R1 and the second resistor R2.

[0059] As an example, the first voltage divider unit 221 includes a first resistor R1 and a second resistor R2, which are connected in series between a voltage source and a ground, and the error amplifier circuit 3 is connected to a connection node between the first resistor R1 and the second resistor R2. When the second voltage divider unit 222 is turned off under the control of a second sensing signal, the first resistor R1 forms a voltage divider on the voltage output by the +5V voltage source, so that the voltage input to the error amplifier circuit 3 is equal to the voltage across the second resistor R2, and the first resistor R1 and the second resistor R2 also play a current limiting role on the current flowing into the error amplifier circuit 3.

[0060] In one embodiment, the second voltage dividing unit 222 includes a third resistor R3, a fourth resistor R4 and a control tube Q1; the first end of the third resistor R3 is connected to the connection node between the first resistor R1 and the second resistor R2, and the second end of the third resistor R3 is connected to the first end of the control tube Q1; the second end of the control tube Q1 is connected to the output end of the radar detection module through the fourth resistor R4, and the third end of the control tube Q1 is grounded, and is used to be turned on under the control of the first sensing signal, or turned off under the control of the second sensing signal.

[0061] As an example, the second voltage divider unit 222 includes a third resistor R3, a fourth resistor R4 and a control tube Q1. The control tube Q1 can be an NMOS tube, the first end of the control tube Q1 is the drain of the NMOS tube, the second end of the control tube Q1 is the gate of the NMOS tube, and the third end of the control tube Q1 is the source of the NMOS tube. The first end of the third resistor R3 is connected to the connection node between the first resistor R1 and the second resistor R2, and the second end of the third resistor R3 is connected to the first end of the control tube Q1; the second end of the control tube Q1 is connected to the output end of the radar detection module through the fourth resistor R4, and the third end of the control tube Q1 is grounded, so that the second voltage divider unit 222 and the second resistor R2 form a parallel structure.

[0062] When the sensing distance between the sensor module 21 and the target object is less than the preset distance, the sensor module 21 can output a first sensing signal, such as a high-level signal, to the control tube Q1, so that the control tube Q1 is turned on, so the second voltage divider unit 222 is turned on, and together with the first voltage divider unit 221, it forms a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 is the first reference voltage; when the sensing distance between the sensor module 21 and the target object is not less than the preset distance, the sensor module 21 can output a second sensing signal, such as a low-level signal, to the control tube Q1, so that the control tube Q1 is turned off, so the second voltage divider unit 222 is turned off, at this time, only the first voltage divider unit 221 forms a voltage divider effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit 3 can be the second reference voltage.

[0063] In one embodiment, the second voltage dividing unit 222 further includes a first capacitor C1; a first end of the first capacitor C1 is connected to a second end of the third resistor R3, and a second end of the first capacitor C1 is connected to a third end of the control tube Q1.

[0064] As an example, the second voltage dividing unit 222 further includes a first capacitor C1. Two ends of the first capacitor C1 are respectively connected to the second end of the third resistor R3 and the third end of the control tube Q1, for filtering out noise signals.

[0065] In one embodiment, an optocoupler feedback module 5 is further provided between the error amplifier circuit 3 and the current output circuit 4; the first end of the optocoupler feedback module 5 is connected to the third end of the error amplifier circuit 3, and the second end of the optocoupler feedback module 5 is used to be connected to the feedback end of the current output circuit 4, and is used to output a feedback current to the current output circuit 4 under the control of the error amplifier circuit 3.

[0066] As an example, an optocoupler feedback module 5 is further provided between the error amplifier circuit 3 and the current output circuit 4. The first end of the optocoupler feedback module 5 is connected to the third end of the error amplifier circuit 3, and the second end of the optocoupler feedback module 5 is used to be connected to the feedback end of the current output circuit 4. The optocoupler feedback module 5 is used to isolate the current output circuit 4 from the error amplifier circuit 3, and output the first feedback current or the second feedback current to the current output circuit 4 according to the current output by the error amplifier circuit 3.

[0067] The utility model also provides a switching power supply circuit. Figure 2 As shown, it includes a current output circuit 4 and a feedback control circuit in any of the above embodiments; the current output circuit 4 includes a primary rectifier and filter module 41, a primary chip 42, a transformer module 43, and a secondary rectifier and filter module 44; the input end of the primary rectifier and filter module 41 is used to connect to the mains circuit, the output end of the primary rectifier and filter module 41 is connected to the primary end of the transformer module 43, the secondary end of the transformer module 43 is connected to the input end of the secondary rectifier and filter module 44, and the output end of the secondary rectifier and filter module 44 is used to connect to an external load; the primary chip 42 is connected to the primary end of the transformer module 43, and is used to output a PWM signal to the transformer module 43; in the feedback control circuit, the input end of the current acquisition circuit 1 is connected to the negative output end of the secondary rectifier and filter module 44, and the third end of the error amplifier circuit 3 is connected to the feedback end of the primary chip 42, and is used to output a feedback current to the primary chip 42, so that the primary chip 42 adjusts the PWM signal according to the feedback current control to adjust the output current of the transformer module 43.

[0068] As an example, the switching power supply circuit includes a current output circuit 4 and a feedback control circuit in any of the above embodiments. The input end of the current output circuit 4 is used to connect to the mains circuit, and the output end is used to connect to an external load, and is used to convert the alternating current output by the mains circuit into direct current available to the external load, and to supply power to the external load. Specifically, it may include a primary rectifier and filter module 41, a primary chip 42, a transformer module 43, and a secondary rectifier and filter module 44. The input end of the primary rectifier and filter module 41 is used to connect to the mains circuit, the output end of the primary rectifier and filter module 41 is connected to the primary end of the transformer module 43, the secondary end of the transformer module 43 is connected to the input end of the secondary rectifier and filter module 44, and the output end of the secondary rectifier and filter module 44 is used to connect to the external load. The primary chip 42 is connected to the primary end of the transformer module 43, and is used to output a PWM signal to the transformer module 43, control the flow direction of the current in the primary winding of the transformer module 43, and use electromagnetic induction to transfer the energy stored in the primary winding of the transformer module 43 to the secondary winding. In the feedback control circuit, the input end of the current acquisition circuit 1 is connected to the negative output end of the secondary rectifier filter module 44, and is used to collect the output current Io of the current output circuit 4 in real time and convert it into a sampling voltage. The second end of the error amplifier circuit 3 is used to obtain the reference voltage generated by the distance sensing circuit 2 according to the sensing distance of the target object. The third end of the error amplifier circuit 3 is connected to the feedback end of the primary chip 42, and is used to output a feedback current to the primary chip 42 according to the comparison result of the reference voltage and the sampling voltage, so that the primary chip 42 controls and adjusts the PWM signal according to the feedback current to adjust the output current of the transformer module 43.

[0069] In this example, a distance sensing circuit 2 is set in the feedback control circuit to sense the sensing distance to the target object, such as the human body, and a reference voltage is output accordingly, so that the operational amplifier U1 performs feedback control on the output current of the current output circuit 4 according to the reference voltage. The output current of the current output circuit 4 can be changed according to the sensing distance of the sensed target object to adjust the electromagnetic radiation of the current output circuit 4 and prevent the electromagnetic radiation from affecting the target object.

[0070] An embodiment of the utility model further provides a charger, comprising the switching power supply circuit in the above embodiment.

[0071] As an example, the charger includes the switching power supply circuit in the above example. In this example, a distance sensing circuit 2 is set in the feedback control circuit to sense the sensing distance to the target object, such as the human body, and a reference voltage is output accordingly, so that the operational amplifier U1 performs feedback control on the output current of the current output circuit 4 according to the reference voltage. The output current of the current output circuit 4 can be changed according to the sensing distance of the sensed target object to adjust the electromagnetic radiation of the current output circuit 4 to prevent the electromagnetic radiation from affecting the target object.

[0072] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A feedback control circuit, characterized in that: It includes a current acquisition circuit, a distance sensing circuit and an error amplification circuit; The first end of the current acquisition circuit is used to be connected to the output end of the current output circuit, and the second end of the current acquisition circuit is connected to the first end of the error amplifier circuit, and is used to output a sampling voltage to the error amplifier circuit according to the output current of the current output circuit; The distance sensing circuit is connected to the second end of the error amplifying circuit and is used to output a reference voltage to the error amplifying circuit according to the sensing distance of the target object; The third terminal of the error amplifier circuit is used to connect to the feedback terminal of the current output circuit, and is used to output a feedback current to the current output circuit according to the sampling voltage and the reference voltage.

2. The feedback control circuit according to claim 1, characterized in that: The distance sensing circuit includes a sensor module and a voltage output module; The sensor module is used to output a sensing signal according to the sensing distance of the target object; The voltage output module is connected to the sensor module and the first end of the error amplifier circuit, and is used to output a sampling voltage to the error amplifier circuit according to the sensing signal.

3. The feedback control circuit according to claim 2, characterized in that: The sensor module includes a radar detection module; The output end of the radar detection module is connected to the voltage output module, and is used to output a first sensing signal to the voltage output module when the sensing distance of the target object is less than a preset distance, or output a second sensing signal to the voltage output module when the sensing distance of the target object is not less than the preset distance; a voltage output module, configured to output a first reference voltage to the error amplifying circuit according to the first sensing signal, or to output a second reference voltage to the error amplifying circuit according to the second sensing signal; The error amplifier circuit is used to output a first feedback current to the current output circuit according to the first reference voltage and the sampling voltage, or to output a second feedback current to the current output circuit according to the second reference voltage and the sampling voltage.

4. The feedback control circuit according to claim 3, characterized in that: The voltage output module includes a first voltage dividing unit and a second voltage dividing unit; A first end of the first voltage dividing unit is connected to a voltage source, and a second end of the first voltage dividing unit is connected to the error amplifying circuit; The second voltage-dividing unit is connected in parallel with the first voltage-dividing unit, and a control end of the second voltage-dividing unit is connected to the sensor module, and is used for being turned on under the control of the first sensing signal, and together with the first voltage-dividing unit, forming a voltage-dividing effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit is the first reference voltage, or being turned off under the control of the second sensing signal, so that the first voltage-dividing unit forms a voltage-dividing effect on the voltage output by the voltage source, so that the voltage input to the error amplifier circuit is the second reference voltage.

5. The feedback control circuit according to claim 4, characterized in that: The first voltage dividing unit includes a first resistor and a second resistor; The first resistor and the second resistor are connected in series between the voltage source and the ground, and the error amplifier circuit is connected to a connection node between the first resistor and the second resistor.

6. The feedback control circuit according to claim 5, characterized in that: The second voltage dividing unit includes a third resistor, a fourth resistor and a control tube; The first end of the third resistor is connected to the connection node between the first resistor and the second resistor, and the second end of the third resistor is connected to the first end of the control tube; The second end of the control tube is connected to the output end of the radar detection module through the fourth resistor, and the third end of the control tube is grounded, and is used to be turned on under the control of the first sensing signal, or turned off under the control of the second sensing signal.

7. The feedback control circuit according to claim 6, characterized in that: The second voltage dividing unit further includes a first capacitor; The first end of the first capacitor is connected to the second end of the third resistor, and the second end of the first capacitor is connected to the third end of the control tube.

8. The feedback control circuit according to claim 1, characterized in that: An optical coupler feedback module is also provided between the error amplification circuit and the current output circuit; The first end of the optocoupler feedback module is connected to the third end of the error amplifier circuit, and the second end of the optocoupler feedback module is used to be connected to the feedback end of the current output circuit, and is used to output feedback current to the current output circuit under the control of the error amplifier circuit.

9. A switching power supply circuit, characterized in that: comprising a current output circuit and a feedback control circuit according to any one of claims 1 to 8; The current output circuit includes a primary rectification and filtering module, a primary chip, a transformer module, and a secondary rectification and filtering module; The input end of the primary rectifier and filter module is used to connect to the mains circuit, the output end of the primary rectifier and filter module is connected to the primary end of the transformer module, the secondary end of the transformer module is connected to the input end of the secondary rectifier and filter module, and the output end of the secondary rectifier and filter module is used to connect to an external load; The primary chip is connected to the primary end of the transformer module and is used to output a PWM signal to the transformer module; In the feedback control circuit, the input end of the current acquisition circuit is connected to the negative output end of the secondary rectifier and filter module, and the third end of the error amplifier circuit is connected to the feedback end of the primary chip, which is used to output feedback current to the primary chip, so that the primary chip adjusts the PWM signal according to the feedback current control to adjust the output current of the transformer module.

10. A charger, characterized in that: Includes the switching power supply circuit as claimed in claim 9.

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