Switching power supply control circuit and switching power supply equipment

Abstract

The utility model relates to the technical field of electronic control, in particular to a control circuit of a switching power supply and switching power supply equipment, and the control circuit of the switching power supply comprises a first power supply circuit, a second power supply circuit, a current detection circuit and a comparison circuit, the current detection circuit is used for detecting the first power supply circuit and transmitting a detection result to the comparison circuit, the comparison circuit compares the detection result and outputs a control signal of the first switching circuit, and on and off of the second power supply circuit are controlled by controlling the first switching circuit. According to the control circuit of the switching power supply, the power supply of the load can be controlled according to the detection result by detecting the first power supply circuit, complex logic does not need to be concentrated in a control chip, the research and development cost of the switching power supply is reduced, the switching power supply is convenient to debug and maintain, and the service life of the switching power supply is prolonged. And the stability and the reliability of the circuit are greatly improved.

Description

Technical Field

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

[0002] A switching power supply is a power conversion circuit that adjusts the output voltage and current by controlling the on-time ratio of semiconductor switching elements. It is widely used in computers, communication equipment, home appliances, battery chargers, LED lighting, and industrial automation.

[0003] In order to control the power supply of the power supply to the load, the switching power supply in the prior art is usually provided with a control circuit, and a special auxiliary power supply is provided to control the control circuit. The control chip of the control circuit controls the power supply to the load according to the actual application situation. However, this control method requires the integration of complex logic in the control chip, which greatly increases the research and development cost of the switching power supply. Utility Model Content

[0004] The embodiments of the utility model provide a control circuit of a switching power supply and a switching power supply device to solve the problem that the switching power supply in the prior art integrates complex logic in the control chip in order to control the power supply to the load, which greatly increases the research and development cost of the switching power supply.

[0005] In a first aspect, the utility model provides a control circuit of a switching power supply, comprising: a first power supply circuit, a second power supply circuit, a current detection circuit and a comparison circuit, wherein:

[0006] The input end of the first power supply circuit is used to connect to a first power supply, the output end of the first power supply circuit is used to connect to a first load, the input end of the second power supply circuit is used to connect to a second power supply, the output end of the second power supply circuit is used to connect to a second load, a sampling branch is serially connected in the first power supply circuit, and a first switch circuit is serially connected in the second power supply circuit;

[0007] The first input end of the current detection circuit is connected to one end of the sampling branch, the second input end of the current detection circuit is connected to the other end of the sampling branch, the output end of the current detection circuit is connected to the first input end of the comparison circuit, the output end of the comparison circuit is electrically connected to the control end of the first switch circuit, and the comparison circuit is used to control the conduction and shutdown of the first switch circuit according to the signal output by the output end of the current detection circuit.

[0008] In one embodiment, the control circuit of the switching power supply further includes: a third power supply circuit, wherein the input end of the third power supply circuit is used to connect to a third power supply, the output end of the third power supply circuit is used to connect to a third load, and the third power supply circuit is serially connected with a second switch circuit;

[0009] The output end of the comparison circuit is electrically connected to the control end of the second switch circuit. The comparison circuit is also used to control the conduction and disconnection of the second switch circuit according to the signal output by the output end of the current detection circuit.

[0010] In one embodiment, the control circuit of the switching power supply further includes: a controller, wherein an input end of the controller is connected to an output end of the comparison circuit, an output end of the controller is connected to a control end of the first switching circuit and a control end of the second switching circuit, and the controller is used to control the conduction and disconnection of the first switching circuit and the second switching circuit according to a signal output from the output end of the comparison circuit.

[0011] In one embodiment, the current detection circuit includes: a first detection branch, a second detection branch, an operational amplifier and a feedback branch, one end of the first detection branch is connected to one end of the sampling branch, the other end of the first detection branch is connected to the same-direction input end of the operational amplifier, one end of the second detection branch is connected to the other end of the sampling branch, the other end of the second detection branch is connected to the reverse input end of the operational amplifier, the output end of the operational amplifier is connected to the first input end of the comparison circuit, one end of the feedback branch is connected to the reverse input end of the operational amplifier, and the other end of the feedback branch is connected to the output end of the operational amplifier.

[0012] In one embodiment, the comparison circuit includes: a comparator and a reference signal branch, the same-direction input end of the comparator is connected to the output end of the current detection circuit, the reverse input end of the comparator is connected to the first output end of the reference signal branch, the output end of the comparator is electrically connected to the control end of the first switching circuit, the input end of the reference signal branch is used to connect to the first power supply, and the second output end of the reference signal branch is grounded.

[0013] In one embodiment, the reference signal branch includes: a first reference resistor and a second reference resistor, one end of the first reference resistor is connected to a first power supply, the other end of the first reference resistor is connected to one end of the second reference resistor, the other end of the first reference resistor is connected to the inverting input end of the comparator, and the other end of the second reference resistor is grounded.

[0014] In one embodiment, the first switching circuit includes: an optocoupler, wherein the anode input terminal of the optocoupler is connected to the output terminal of the comparison circuit, the cathode input terminal of the optocoupler is grounded, the collector input terminal of the optocoupler is used to connect to the second power supply, and the emitter output terminal of the optocoupler is used to connect to the second load.

[0015] In one embodiment, the first switch circuit includes: a switch tube, a control end of the switch tube is connected to the output end of the comparison circuit, an input end of the switch tube is used to connect to the second power supply, and an output end of the switch tube is used to connect to the second load.

[0016] In one implementation, the sampling branch includes a sampling resistor, one end of the sampling resistor is connected to the negative terminal of the first load, and the other end of the sampling resistor is connected to the negative terminal of the first power supply.

[0017] In a second aspect, the present embodiment provides a switching power supply device, the switching power supply device comprising a housing and a circuit board arranged in the housing, the circuit board being provided with a control circuit of the switching power supply as described in the first aspect and its improvement.

[0018] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0019] The control circuit of the switching power supply of the utility model comprises a first power supply circuit, a second power supply circuit, a current detection circuit and a comparison circuit. The first power supply circuit is detected by the current detection circuit, and the detection result is transmitted to the comparison circuit. The comparison circuit outputs a control signal of the first switch circuit after comparison. The on and off of the second power supply circuit are controlled by controlling the first switch circuit. The control circuit of the switching power supply of the utility model can control the power supply of the load according to the detection result by detecting the first power supply circuit, and does not need to concentrate complex logic in the control chip. While reducing the research and development cost of the switching power supply, the switching power supply is easy to debug and maintain, which greatly improves the stability and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 It is a schematic diagram of the module structure of a control circuit of a switching power supply provided in one embodiment of the utility model;

[0022] Figure 2 This is a circuit connection diagram of a current detection circuit provided by an embodiment of the utility model;

[0023] Figure 3 It is a circuit connection diagram of a comparison circuit provided by an embodiment of the utility model;

[0024] Figure 4 This is a circuit connection diagram of a first switch circuit provided in one embodiment of the utility model;

[0025] Figure 5 This is a circuit connection diagram of a first switch circuit provided in one embodiment of the utility model;

[0026] Figure 6 It is a circuit connection diagram of a sampling circuit provided in one embodiment of the utility model;

[0027] Among them, 1. first power supply circuit, 2. second power supply circuit, 3. current detection circuit, 4. comparison circuit, 5. first load, 6. second load, 7. third power supply circuit, 8. third load, 11. sampling branch, 21. first switch circuit, 31. first detection branch, 32. second detection branch, 33. feedback branch, 71. second switch circuit. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0029] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention 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 invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] 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.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. It will be further understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0033] like Figure 1 As shown, a schematic diagram of the module structure of a control circuit of a switching power supply is provided.

[0034] In one embodiment, if Figure 1 As shown, the control circuit of the switching power supply includes: a first power supply circuit 1, a second power supply circuit 2, a current detection circuit 3 and a comparison circuit 4, wherein:

[0035] The input end of the first power supply circuit 1 is used to connect to the first power supply, the output end of the first power supply circuit 1 is used to connect to the first load 5, the input end of the second power supply circuit 2 is used to connect to the second power supply, the output end of the second power supply circuit 2 is used to connect to the second load 6, the first power supply circuit 1 is serially provided with a sampling branch 11, and the second power supply circuit 2 is serially provided with a first switch circuit 21;

[0036] The first input end of the current detection circuit 3 is connected to one end of the sampling branch 11, the second input end of the current detection circuit 3 is connected to the other end of the sampling branch 11, the output end of the current detection circuit 3 is connected to the first input end of the comparison circuit 4, the output end of the comparison circuit 4 is electrically connected to the control end of the first switch circuit 21, and the comparison circuit 4 is used to control the conduction and shutdown of the first switch circuit 21 according to the signal output by the output end of the current detection circuit 3.

[0037] It is understandable that the first power supply can be a 220V AC power supply, and the first power supply can also use a converter to convert the AC power supply to a signal. Preferably, the first power supply is a signal converted by the AC / DC converter. The first load 5 includes a control chip. When the control chip is in standby mode, it forms a loop with the first unit to maintain the lowest power consumption state. At this time, the current in the first power supply circuit 1 is relatively small; when the control chip is in working mode, the current in the first power supply circuit 1 is relatively large.

[0038] The second power supply can be a 220V AC power supply, or a signal obtained by converting the AC power supply using a converter. Preferably, the second power supply is a signal obtained by converting the AC power supply through an AC / DC converter. The AC / DC converter connected to the second power supply can be an AC / DC converter of the same specification as the AC / DC converter connected to the first power supply, or the AC / DC converter connected to the second power supply can be an AC / DC converter of a different specification from the AC / DC converter connected to the first power supply.

[0039] Only a sampling branch 11 may be provided in the first power supply circuit 1, a protection circuit may be provided in the first power supply circuit 1, a filtering circuit may be provided in the first power supply circuit 1, any circuit may be provided in the first power supply circuit 1 according to actual application conditions, only one sampling resistor may be provided in the sampling branch 11, or the sampling branch 11 may be provided with multiple sampling internal resistors.

[0040] Only the first switch circuit 21 may be provided in the second power supply circuit 2, a protection circuit may also be provided in the second power supply circuit 2, a filter circuit may also be provided in the second power supply circuit 2, and any circuit may be provided in the second power supply circuit 2 according to actual application conditions. The first switch circuit 21 may be any switch circuit, a switch tube may be provided in the first switch circuit 21, and the power supply to the second load 6 may be controlled by turning on and off the switch tube; an optocoupler may also be provided in the first switch circuit 21, and the power supply to the second load 6 may be controlled by turning on and off the optocoupler, and a relay may also be provided in the first switch circuit 21, and the power supply to the second load 6 may be controlled by turning on and off the relay.

[0041] The current detection circuit 3 may only include a protection resistor, and the current detection circuit 3 may also include an amplifier to amplify the collected signal.

[0042] The working process of the control circuit of the above-mentioned switching power supply is: the control chip is powered by the first power supply, and the current detection circuit 3 detects the signals at both ends of the sampling branch 11. When the control chip is in the standby state, the signal detected by the current detection circuit 3 is small. When the comparison circuit 4 obtains a small signal, it outputs a shutdown signal of the first switch circuit 21, and the second power supply cannot supply power to the second load 6 through the second power supply circuit 2. When the control chip is in the working state, the signal detected by the current detection circuit 3 is large. When the comparison circuit 4 obtains a large signal, it outputs a conduction signal of the first switch circuit 21, and the second power supply supplies power to the second load 6 through the second power supply circuit 2.

[0043] The control circuit of the switching power supply of the present embodiment comprises a first power supply circuit 1, a second power supply circuit 2, a current detection circuit 3 and a comparison circuit 4. The current detection circuit 3 is used to detect the first power supply circuit 1, and the detection result is transmitted to the comparison circuit 4. The comparison circuit 4 outputs a control signal of the first switch circuit 21 after comparison. By controlling the first switch circuit 21, the conduction and shutdown of the second power supply circuit 2 are controlled. The control circuit of the switching power supply of the present utility model can control the power supply of the load according to the detection result by detecting the first power supply circuit 1, and does not need to concentrate complex logic in the control chip. While reducing the R&D cost of the switching power supply, the switching power supply is easy to debug and maintain, which greatly improves the stability and reliability of the circuit.

[0044] In one embodiment, if Figure 1 As shown, on the basis of the above embodiment, the control circuit of the switching power supply further includes: a third power supply circuit 7, the input end of the third power supply circuit 7 is used to connect the third power supply, the output end of the third power supply circuit 7 is used to connect the third load 8, and the third power supply circuit 7 is provided with a second switch circuit 71 in series;

[0045] The output end of the comparison circuit 4 is electrically connected to the control end of the second switch circuit 71 . The comparison circuit 4 is also used to control the on and off of the second switch circuit 71 according to the signal output by the output end of the current detection circuit 3 .

[0046] The third power supply can be a 220V AC power supply, and the third power supply can also use a converter to convert the AC power supply to a signal. Preferably, the third power supply is a signal converted by the AC / DC converter. Only the second switch circuit 71 can be set in the third power supply circuit 7, and a protection circuit can also be set in the third power supply circuit 7. A filter circuit can also be set in the third power supply circuit 7. Any circuit can be set in the third power supply circuit 7 according to actual application conditions. The second switch circuit 71 can be the same as the first switch circuit 21. When the first switch circuit 21 is turned on, the second switch circuit 71 is also turned on; the second switch circuit 71 can also be different from the first switch circuit 21. When the first switch circuit 21 is turned on, the second switch circuit 71 is turned off, and when the first switch circuit 21 is turned off, the second switch circuit 71 is turned on. It can be set according to actual application conditions.

[0047] It is understandable that if power supply is required for multiple loads, a fourth power supply circuit and a fifth power supply circuit may be provided as required.

[0048] The working process of the control circuit of the above-mentioned switching power supply is: the control chip is powered by the first power supply, and the current detection circuit 3 detects the signals at both ends of the sampling branch 11. When the control chip is in the standby state, the signal detected by the current detection circuit 3 is small. When the comparison circuit 4 obtains a small signal, it outputs the shutdown signal of the first switch circuit 21 and the second switch circuit 71, and the second power supply cannot supply power to the second load 6 through the second power supply circuit 2, and the third power supply cannot supply power to the third load 8 through the third power supply circuit 7; when the control chip is in the working state, the signal detected by the current detection circuit 3 is large. When the comparison circuit 4 obtains a large signal, it outputs the conduction signal of the first switch circuit 21 and the second switch circuit 71, and the second power supply supplies power to the second load 6 through the second power supply circuit 2, and the third power supply supplies power to the third load 8 through the third power supply circuit 7.

[0049] The control circuit of the switching power supply of this embodiment is provided with a third power supply circuit 7. By controlling the second switch circuit 71 in the third power supply circuit 7, the third power supply is controlled to charge the third load 8. The circuit structure is simple, and the switching power supply can meet more application scenarios while reducing the cost of the circuit.

[0050] In one embodiment, if Figure 1As shown, based on the above embodiment, the control circuit of the switching power supply further includes: a controller 9, the input end of the controller 9 is connected to the output end of the comparison circuit 4, the output end of the controller 9 is connected to the control end of the first switch circuit 21 and the control end of the second switch circuit 71, and the controller 9 is used to control the conduction and shutdown of the first switch circuit 21 and the second switch circuit 71 according to the signal output by the output end of the comparison circuit 4.

[0051] It is understandable that the controller 9 can be a single-chip microcomputer, the controller 9 can only control the first switch circuit 21, the controller 9 can only control the second switch circuit 71, the controller 9 can also control both the first switch circuit 21 and the second switch circuit 71. As another embodiment, the controller 9 can also be a control circuit.

[0052] The working process of the control circuit of the above-mentioned switching power supply is as follows: when the comparison circuit 4 obtains a smaller signal, it outputs a low-level signal to the controller 9, and the controller 9 generates a shutdown signal of the first switch circuit 21 and the second switch circuit 71 according to the low-level signal at its input end, so that the second power supply cannot supply power to the second load 6 through the second power supply circuit 2, and the third power supply cannot supply power to the third load 8 through the third power supply circuit 7; when the comparator obtains a larger signal, it outputs a high-level signal to the controller 9, and the controller 9 generates a turn-on signal of the first switch circuit 21 and the second switch circuit 71 according to the high-level signal at its input end, and the second power supply supplies power to the second load 6 through the second power supply circuit 2, and the third power supply supplies power to the third load 8 through the third power supply circuit 7.

[0053] In the control circuit of the switching power supply of this embodiment, a controller 9 is arranged between the comparison circuit 4 and the switching circuit, so that the control of the circuit is more precise, and the accuracy and stability of the circuit are further improved.

[0054] In one embodiment, if Figure 2 As shown, a circuit connection diagram of a current detection circuit 3 is provided. On the basis of the above embodiment, the current detection circuit 3 includes: a first detection branch 31, a second detection branch 32, an operational amplifier U1 and a feedback branch 33. One end of the first detection branch 31 is connected to one end of the sampling branch 11, and the other end of the first detection branch 31 is connected to the same-direction input end of the operational amplifier U1. One end of the second detection branch 32 is connected to the other end of the sampling branch 11, and the other end of the second detection branch 32 is connected to the reverse input end of the operational amplifier U1. The output end of the operational amplifier U1 is connected to the first input end of the comparison circuit 4, one end of the feedback branch 33 is connected to the reverse input end of the operational amplifier U1, and the other end of the feedback branch 33 is connected to the output end of the operational amplifier U1.

[0055] The parameters of the resistors in the feedback branch 33, the first detection branch 31 and the second detection branch 32 can be set according to actual application conditions, so that the operational amplifier U1 can accurately amplify the signal at its input end while reducing signal loss.

[0056] The working process of the control circuit of the above-mentioned switching power supply is: the signals at both ends of the sampling branch 11 flow to the operational amplifier U1 through the first detection branch 31 and the second detection branch 32, and the operational amplifier U1 forms negative feedback through the feedback branch 33 to amplify the signals at both ends of the sampling branch 11.

[0057] The control circuit of the switching power supply of this embodiment sets an operational amplifier U1 in the current detection circuit 3 for differential amplification, which is beneficial for the comparison circuit 4 at the rear stage to compare the signal and further ensures the stability of the circuit.

[0058] like Figure 3 As shown, a circuit connection diagram of a comparison circuit 4 is provided.

[0059] In one embodiment, if Figure 3 As shown, on the basis of the above embodiment, the comparison circuit 4 includes: a comparator IC2 and a reference signal branch 41, the same-direction input end of the comparator IC2 is connected to the output end of the current detection circuit 3, the reverse input end of the comparator IC2 is connected to the first output end of the reference signal branch 41, the output end of the comparator IC2 is electrically connected to the control end of the first switch circuit 21, the input end of the reference signal branch 41 is used to connect to the first power supply, and the second output end of the reference signal branch 41 is grounded.

[0060] The working process of the control circuit of the above-mentioned switching power supply is: after the comparator IC2 receives the signal of the current detection circuit 3, it compares the signal at the output end of the current detection circuit 3 with the reference signal provided by the reference signal branch 41. If the signal at the output end of the current detection circuit 3 is greater than the reference signal, a high-level signal is output to control the switch circuit to be turned on. If the signal at the output end of the current detection circuit 3 is less than the reference signal, a low-level signal is output to control the switch circuit to be turned off.

[0061] The control circuit of the switching power supply of this embodiment sets a comparator IC2 and a reference signal branch 41 in the comparison circuit 4, and uses the reference signal branch 41 to provide a reference signal. The reference signal branch 41 can provide a very stable and accurate reference voltage or current, which enables the comparator IC2 to perform signal comparison based on this accurate reference value, thereby improving the accuracy and reliability of the comparison circuit 4.

[0062] In one embodiment, if Figure 3As shown, based on the above embodiment, the reference signal branch 41 includes: a first reference resistor R1 and a second reference resistor R2, one end of the first reference resistor R1 is connected to a first power supply, the other end of the first reference resistor R1 is connected to one end of the second reference resistor R2, the other end of the first reference resistor R1 is connected to the reverse input end of the comparator IC2, and the other end of the second reference resistor R2 is grounded.

[0063] In the control circuit of the switching power supply of this embodiment, the first reference resistor R1 and the second reference resistor R2 form a voltage divider circuit, and the voltage division of the resistors is used to provide a reference signal for the comparator IC2. It is easy to implement and low-cost, and is applicable to various voltage levels and signal ranges, so that the same circuit can adapt to different application requirements.

[0064] In one embodiment, if Figure 4 As shown, a circuit connection diagram of a first switch circuit 21 is provided. On the basis of the above embodiment, the first switch circuit 21 includes: an optocoupler U2, the anode input terminal of the optocoupler U2 is connected to the output terminal of the comparison circuit 4, the cathode input terminal of the optocoupler U2 is grounded, the collector input terminal of the optocoupler U2 is used to connect to the second power supply, and the emitter output terminal of the optocoupler U2 is used to connect to the second load 6.

[0065] In the control circuit of the switching power supply of this embodiment, an optocoupler U2 is arranged in the switching circuit to control the on and off of the first power supply circuit 1. The optocoupler U2 transmits messages between the input side and the output side through optical signals to achieve true electrical isolation, which can effectively prevent high voltage or interference signals from being transmitted from one side to the other side, and can better protect the controller 9.

[0066] In one embodiment, if Figure 5 As shown, a circuit connection diagram of a first switch circuit 21 is provided. On the basis of the above embodiment, the first switch circuit 21 includes: a switch tube Q2, the control end of the switch tube Q2 is connected to the output end of the comparison circuit 4, the input end of the switch tube Q2 is used to connect the second power supply, and the output end of the switch tube Q2 is used to connect the second load 6.

[0067] It is understandable that the switch tube Q2 can be any type of switch tube. The switch tube Q2 can be a MOS tube, a triode, or a field effect tube. Preferably, the switch tube Q2 is a MOS tube.

[0068] The control circuit of the switching power supply of this embodiment sets a switching tube in the switching circuit to control the conduction and shutdown of the first power supply circuit 1. The control precision of the switching tube is high, the response speed is fast, and the cost of the switching tube is low, which further reduces the cost of the switching power supply.

[0069] In one embodiment, if Figure 6 As shown, a circuit connection diagram of a sampling branch 11 is provided. Based on the above embodiment, the sampling branch 11 includes a sampling resistor R1, one end of the sampling resistor R1 is connected to the negative terminal of the first load 5, and the other end of the sampling resistor R1 is connected to the negative terminal of the first power supply.

[0070] The control circuit of the switching power supply of this embodiment is provided with a sampling resistor R1 in the sampling branch 11, which can convert the current into a measurable voltage drop, thereby realizing indirect measurement of the current.

[0071] In one embodiment, a switching power supply device is provided. The switching power supply device includes a housing and a circuit board arranged in the housing. The circuit board is provided with a control circuit of the switching power supply mentioned in any of the above embodiments.

[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 control circuit of a switching power supply, characterized in that: include: A first power supply circuit, a second power supply circuit, a current detection circuit and a comparison circuit, wherein: The input end of the first power supply circuit is used to connect to a first power supply, the output end of the first power supply circuit is used to connect to a first load, the input end of the second power supply circuit is used to connect to a second power supply, the output end of the second power supply circuit is used to connect to a second load, a sampling branch is serially connected in the first power supply circuit, and a first switch circuit is serially connected in the second power supply circuit; The first input end of the current detection circuit is connected to one end of the sampling branch, the second input end of the current detection circuit is connected to the other end of the sampling branch, the output end of the current detection circuit is connected to the first input end of the comparison circuit, the output end of the comparison circuit is electrically connected to the control end of the first switch circuit, and the comparison circuit is used to control the conduction and shutdown of the first switch circuit according to the signal output by the output end of the current detection circuit.

2. The control circuit of the switching power supply according to claim 1, characterized in that: The control circuit of the switching power supply further includes: a third power supply circuit, wherein the input end of the third power supply circuit is used to connect to a third power supply, the output end of the third power supply circuit is used to connect to a third load, and a second switch circuit is serially connected in the third power supply circuit; The output end of the comparison circuit is electrically connected to the control end of the second switch circuit. The comparison circuit is also used to control the conduction and disconnection of the second switch circuit according to the signal output by the output end of the current detection circuit.

3. The control circuit of the switching power supply according to claim 2, characterized in that: The control circuit of the switching power supply also includes: a controller, wherein the input end of the controller is connected to the output end of the comparison circuit, the output end of the controller is connected to the control end of the first switching circuit and the control end of the second switching circuit, and the controller is used to control the conduction and shutdown of the first switching circuit and the second switching circuit according to the signal output by the output end of the comparison circuit.

4. The control circuit of the switching power supply according to claim 1, characterized in that: The current detection circuit includes: a first detection branch, a second detection branch, an operational amplifier and a feedback branch, one end of the first detection branch is connected to one end of the sampling branch, the other end of the first detection branch is connected to the same-direction input end of the operational amplifier, one end of the second detection branch is connected to the other end of the sampling branch, the other end of the second detection branch is connected to the reverse input end of the operational amplifier, the output end of the operational amplifier is connected to the first input end of the comparison circuit, one end of the feedback branch is connected to the reverse input end of the operational amplifier, and the other end of the feedback branch is connected to the output end of the operational amplifier.

5. The control circuit of the switching power supply according to claim 1, characterized in that: The comparison circuit includes: a comparator and a reference signal branch, the same-direction input end of the comparator is connected to the output end of the current detection circuit, the reverse input end of the comparator is connected to the first output end of the reference signal branch, the output end of the comparator is electrically connected to the control end of the first switch circuit, the input end of the reference signal branch is used to connect to the first power supply, and the second output end of the reference signal branch is grounded.

6. The control circuit of the switching power supply according to claim 5, characterized in that: The reference signal branch includes: a first reference resistor and a second reference resistor, one end of the first reference resistor is connected to a first power supply, the other end of the first reference resistor is connected to one end of the second reference resistor, the other end of the first reference resistor is connected to the inverting input end of the comparator, and the other end of the second reference resistor is grounded.

7. The control circuit of the switching power supply according to claim 1, characterized in that: The first switching circuit includes: an optocoupler, wherein the anode input terminal of the optocoupler is connected to the output terminal of the comparison circuit, the cathode input terminal of the optocoupler is grounded, the collector input terminal of the optocoupler is used to connect to the second power supply, and the emitter output terminal of the optocoupler is used to connect to the second load.

8. The control circuit of the switching power supply according to claim 1, characterized in that: The first switch circuit includes: a switch tube, a control end of the switch tube is connected to the output end of the comparison circuit, an input end of the switch tube is used to connect to the second power supply, and an output end of the switch tube is used to connect to the second load.

9. The control circuit of the switching power supply according to claim 2, characterized in that: The sampling branch includes a sampling resistor, one end of the sampling resistor is connected to the negative terminal of the first load, and the other end of the sampling resistor is connected to the negative terminal of the first power supply.

10. A switching power supply device, characterized in that: The switching power supply device comprises a housing and a circuit board arranged in the housing, wherein the control circuit of the switching power supply according to any one of claims 1 to 9 is arranged in the circuit board.

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