A multi-output voltage sampling feedback circuit, method and switching power supply

Abstract

The application discloses a multi-output voltage sampling feedback circuit, a method and a switching power supply, and the circuit comprises a first switch module, a second switch module, a main feedback sampling module, a voltage reduction module, at least one secondary feedback sampling module, a voltage stabilizing module and an output module; the first switch module is connected with a standby control signal, and is used for controlling the second switch module to be turned on or turned off, and controlling the main feedback sampling module and the voltage reduction module to be turned on or turned off; the second switch module is used for controlling the secondary feedback sampling module and the voltage stabilizing module to be turned on or turned off; the main feedback sampling module is used for collecting a main output voltage; the secondary feedback sampling module is used for collecting a secondary output voltage; the voltage reduction module is used for reducing the value of the main output voltage; the output module is used for outputting a sampling signal; and the voltage stabilizing module is used for stabilizing the size of the sampling signal. The application can turn off the secondary feedback sampling module while reducing the main output voltage, so as to turn off the unnecessary output voltage sampling feedback circuit, and then reduce standby power consumption.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to a multi-channel output voltage sampling feedback circuit, method, and switching power supply. Background Technology

[0002] For a transformer-output line with multiple voltage outputs, to achieve good cross-regulation of the multiple output voltages, all output voltages are sampled and fed back. The output voltage with the highest voltage ripple requirement constitutes the majority of the total feedback, and is considered the primary output voltage. The others are considered secondary output voltages. During normal operation, both the primary and secondary output voltages require sampling and feedback.

[0003] However, in standby mode, usually only one output voltage is needed to power the load (main output voltage), but the voltages of the other output paths will still participate in voltage feedback regulation, which will generate additional power consumption, thus increasing standby power consumption.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a multi-channel output voltage sampling feedback circuit, method and switching power supply to solve the problem of increased standby power consumption in the existing multi-channel output voltage sampling feedback circuit of transformer.

[0006] The technical solution of the present invention is as follows:

[0007] A multi-channel output voltage sampling feedback circuit includes: a first switching module, a second switching module, a main feedback sampling module, a step-down module, at least one secondary feedback sampling module, a voltage regulator module, and an output module.

[0008] The first switch module receives a standby control signal and is connected to the second switch module, the main feedback sampling module, the step-down module, and the voltage regulator module respectively. The first switch module is used to control the second switch module to turn on or off, and to control the main feedback sampling module and the step-down module to be connected and disconnected.

[0009] The second switching module is connected to the first switching module, the main feedback sampling module, the step-down module, the secondary feedback sampling module, the voltage regulator module, and the output module, respectively. The second switching module is used to control the on / off connection between the secondary feedback sampling module and the voltage regulator module.

[0010] The main feedback sampling module is used to acquire the main output voltage; the secondary feedback sampling module is used to acquire the secondary output voltage.

[0011] The step-down module is connected to the main output voltage and is connected to the first switching module. The step-down module is used to reduce the value of the main output voltage.

[0012] The output module is connected to the main feedback sampling module and the voltage regulation module respectively, and the output module is used to output the sampling signal;

[0013] The voltage regulator module is connected to the main feedback sampling module, the first switch module, the second switch module and the output module respectively, and the voltage regulator module is used to stabilize the magnitude of the sampling signal.

[0014] In a further embodiment of the present invention, the first switching module includes: a first resistor, a second resistor, a first transistor, and a second transistor; wherein,

[0015] One end of the first resistor is connected to the standby control signal, and the other end of the first resistor is connected to one end of the second resistor and the base of the first transistor;

[0016] The other end of the second resistor is grounded;

[0017] The collector of the first transistor is connected to the base of the second transistor, and the emitter of the first transistor is grounded.

[0018] The collector of the second transistor is connected to the second switching module and the buck module, respectively, and the emitter of the second transistor is connected to the main feedback sampling module and the voltage regulator module, respectively.

[0019] In a further embodiment of the present invention, the second switching module includes: a third transistor; wherein,

[0020] The base of the third transistor is connected to the collector of the second transistor and the step-down module, the collector of the third transistor is connected to the secondary feedback sampling module, and the emitter of the third transistor is connected to the main feedback sampling module and the voltage regulator module.

[0021] In a further embodiment of the present invention, the second switching module includes: a fourth transistor and a diode; wherein,

[0022] The base of the fourth transistor is connected to the collector of the second transistor and the step-down module, the collector of the fourth transistor is connected to the cathode of the diode, and the emitter of the fourth transistor is connected to the main feedback sampling module and the voltage regulation module.

[0023] The anode of the diode is connected to the secondary feedback sampling module.

[0024] In a further embodiment of the present invention, the main feedback sampling module includes: a third resistor and a fourth resistor; wherein,

[0025] One end of the third resistor is connected to the main output voltage and to the output module, and the other end of the third resistor is connected to the voltage regulator module and one end of the fourth resistor, respectively.

[0026] The other end of the fourth resistor is grounded;

[0027] The step-down module includes: a fifth resistor; wherein...

[0028] One end of the fifth resistor is connected to the main output voltage, and the other end of the fifth resistor is connected to the collector of the second transistor.

[0029] In a further embodiment of the present invention, the secondary feedback sampling module includes: a sixth resistor; wherein,

[0030] One end of the sixth resistor is connected to the secondary output voltage, and the other end of the sixth resistor is connected to the collector of the third transistor.

[0031] In a further embodiment of the present invention, the output module includes: a seventh resistor, an eighth resistor, and an optocoupler; wherein,

[0032] One end of the seventh resistor is connected to the main output voltage, and the other end of the seventh resistor is connected to the first pin of the optocoupler and one end of the eighth resistor, respectively.

[0033] The other end of the eighth resistor is connected to the second pin of the optocoupler;

[0034] The second pin of the optocoupler is also connected to the voltage regulator module, the third pin of the optocoupler is connected to the ground pin of the control chip, and the fourth pin of the optocoupler is connected to the feedback pin of the control chip.

[0035] In a further embodiment of the present invention, the voltage regulator module includes: a three-terminal voltage regulator, a ninth resistor, a first capacitor, and a second capacitor; wherein,

[0036] The cathode of the three-terminal voltage regulator is connected to the second pin of the optocoupler;

[0037] The ninth resistor is connected in series with the first capacitor and then in parallel between the cathode and the reference terminal of the three-terminal voltage regulator.

[0038] The second capacitor is connected in parallel between the cathode and the reference terminal of the three-terminal regulator;

[0039] The anode of the three-terminal voltage regulator is grounded.

[0040] Based on the same inventive concept, the present invention also provides a switching power supply, which includes a control chip, a transformer for outputting multiple output voltages, and a multi-output voltage sampling feedback circuit as described above; wherein,

[0041] The multi-output voltage feedback circuit is connected to the control chip and is used to collect the multi-output voltage output by the transformer.

[0042] The control chip is connected to the multi-channel output voltage sampling feedback circuit and the transformer, respectively, and is used to adjust the output voltage of the transformer according to the sampling signal fed back by the multi-channel output voltage feedback circuit.

[0043] Based on the same inventive concept, the present invention also provides a multi-output voltage sampling feedback method applied to the above-described multi-output voltage sampling feedback circuit, comprising:

[0044] When the standby control signal is a high-level signal, the first switch module controls the second switch module to turn on, and both the main feedback sampling module and the secondary feedback sampling module participate in the feedback sampling of the output voltage.

[0045] When the standby control signal is a low level signal, the first switch module controls the second switch module to turn off and connect the buck module and the main feedback sampling module, so as to reduce the main output voltage and disconnect the secondary feedback sampling module at the same time.

[0046] This invention provides a multi-channel output voltage sampling feedback circuit, method, and switching power supply. The circuit includes: a first switching module, a second switching module, a main feedback sampling module, a buck module, at least one secondary feedback sampling module, a voltage regulator module, and an output module. The first switching module receives a standby control signal and is connected to the second switching module, the main feedback sampling module, the buck module, and the voltage regulator module, respectively. The first switching module controls the second switching module to turn on or off, and controls the connection and disconnection of the main feedback sampling module and the buck module. The second switching module is connected to the first switching module, the main feedback sampling module, the buck module, and the secondary feedback sampling module, respectively. The system includes a voltage regulator module connected to the main feedback sampling module, a second switching module controlling the connection between the secondary feedback sampling module and the voltage regulator module, a main feedback sampling module for acquiring the main output voltage, a secondary feedback sampling module for acquiring the secondary output voltage, a buck module connected to the first switching module, the buck module receiving the main output voltage and reducing its value, an output module connected to both the main feedback sampling module and the voltage regulator module, and an output module for outputting a sampling signal, and a voltage regulator module connected to the main feedback sampling module, the first switching module, the second switching module, and the output module, and a voltage regulator module for stabilizing the magnitude of the sampling signal. This invention, by setting a second switching module between the output module and the first switching module, allows the second switching module to disconnect when the standby control signal is low, controlling the buck module to connect to the main feedback sampling module. This disconnects the secondary feedback sampling module while reducing the main output voltage, thereby eliminating unnecessary output voltage sampling feedback lines and reducing standby power consumption. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0048] Figure 1 This is a functional module architecture diagram of the multi-output voltage sampling feedback circuit in this invention.

[0049] Figure 2 This is a circuit diagram of a multi-channel output voltage sampling feedback circuit in one embodiment of the present invention.

[0050] Figure 3 This is a circuit diagram of a multi-output voltage sampling feedback circuit in another embodiment of the present invention.

[0051] Figure 4 This is a circuit diagram of a multi-channel output voltage sampling feedback circuit in another embodiment of the present invention.

[0052] Figure 5 This is a flowchart illustrating the multi-channel output voltage sampling feedback method in this invention.

[0053] The markings in the attached diagram are as follows: 100, first switching module; 200, second switching module; 300, main feedback sampling module; 400, step-down module; 500, secondary feedback sampling module; 600, voltage regulator module; 700, output module. Detailed Implementation

[0054] This invention provides a multi-channel output voltage sampling feedback circuit, method, and switching power supply. The multi-channel output voltage sampling feedback circuit can be used in switching power supplies and LED driver circuits. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0055] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0056] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0057] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0058] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0059] The inventors discovered that for a transformer-output multi-voltage line, the multi-output voltage sampling feedback circuit exhibits significant standby power consumption in standby mode. To address this, existing solutions reduce the main output voltage to a lower value than the normal operating voltage, and the secondary output voltage is also reduced to a lower value than the normal operating voltage due to the transformer turns ratio. This reduces losses at the main output voltage input and power consumption caused by leakage current in the sampling circuit and capacitors at the secondary output voltage input, resulting in low power consumption in standby mode. However, in standby mode, typically only one output voltage (the main output voltage) supplies power to the load, but the voltages of the other output paths still participate in voltage feedback regulation. This causes additional power consumption in the sampling resistors of these feedback regulation paths, thus increasing standby power consumption.

[0060] To address the aforementioned technical problems, this invention provides a multi-channel output voltage sampling feedback circuit, method, and switching power supply. By setting a second switching module between the output module and the first switching module, when the standby control signal is a low-level signal, the first switching module controls the second switching module to disconnect, and the buck module is connected to the main feedback sampling module. In this way, the secondary feedback sampling module can be disconnected while reducing the main output voltage, thereby disconnecting unnecessary output voltage sampling feedback loops and reducing standby power consumption.

[0061] Please also refer to Figures 1 to 4 The present invention provides a preferred embodiment of a switching power supply.

[0062] This invention provides a switching power supply, comprising a control chip, a transformer for outputting multiple output voltages, and a multi-output voltage sampling feedback circuit as described above. The multi-output voltage feedback circuit is connected to the control chip and is used to acquire the multiple output voltages output by the transformer. The control chip is connected to both the multi-output voltage sampling feedback circuit and the transformer, and is used to adjust the magnitude of the transformer's output voltage based on the sampling signals fed back by the multi-output voltage feedback circuit.

[0063] Specifically, the control chip is a PWM control chip, and the sampling signal is a signal fed back to the control chip by multiple output voltages in different proportions. The control chip is connected to the transformer through a MOSFET, and adjusts the driving frequency or duty cycle according to the sampling signal fed back by the multiple output voltage sampling feedback circuit, thereby adjusting the magnitude of the transformer's output voltage.

[0064] like Figure 1 As shown, in some embodiments, the multi-channel output voltage sampling feedback circuit includes: a first switching module 100, a second switching module 200, a main feedback sampling module 300, a step-down module 400, at least one secondary feedback sampling module 500, a voltage regulator module 600, and an output module 700. The first switching module 100 receives a standby control signal and is connected to the second switching module 200, the main feedback sampling module 300, the step-down module 400, and the voltage regulator module 600, respectively. The first switching module 100 controls the second switching module 200 to turn on or off, and controls the conduction and disconnection of the main feedback sampling module 300 and the step-down module 400. The second switching module 200 is connected to the first switching module 100, the main feedback sampling module 300, the step-down module 400, the secondary feedback sampling module 500, and the voltage regulator module 600, respectively. The second switching module 200 controls the secondary feedback sampling module 500 and the voltage regulator module 600, respectively. The circuit consists of a main feedback sampling module 300 and a secondary feedback sampling module 500. The main feedback sampling module 300 is used to acquire the main output voltage. The secondary feedback sampling module 500 is used to acquire the secondary output voltage. The step-down module 400 is connected to the main output voltage and to the first switch module 100, and is used to reduce the value of the main output voltage. The output module 700 is connected to both the main feedback sampling module 300 and the voltage regulator module 600, and is used to output the sampling signal. The voltage regulator module 600 is connected to the main feedback sampling module 300, the first switch module 100, the second switch module 200, and the output module 700, and is used to stabilize the magnitude of the sampling signal.

[0065] Specifically, the main feedback sampling module 300 collects the main output voltage (main feedback voltage), and the secondary feedback sampling module 500 collects the secondary output voltage (secondary feedback voltage). The feedback amount of the main output voltage accounts for the majority of the total feedback amount. The number of secondary feedback sampling modules 500 is set according to the number of output voltage channels of the transformer. When the product is in standby mode, only one output voltage is needed to power the product load. The voltages collected by the main feedback sampling module 300 and the secondary feedback sampling module are output to the control chip through the output module 700 using the same sampling signal. The voltage regulator module 600 serves to stabilize the voltage.

[0066] When the standby signal is a high-level signal, the product operates normally. The first switch module 100 controls the second switch module 200 to open according to the standby control signal. The main feedback sampling module 300 and the secondary feedback sampling module 500 perform sampling normally. Both the main feedback sampling module 300 and the secondary feedback sampling module 500 participate in the feedback. The step-down module 400 does not participate in the feedback of the main feedback sampling module 300. The output voltages of each channel are in a good cross-adjustment state.

[0067] When the device enters standby mode, the standby control signal is low. The first switch module 100 controls the second switch module 200 to disconnect. The step-down module 400 is connected to the main feedback sampling module 300 to reduce the main output voltage. Due to the turns ratio of the transformer, the secondary output voltage will also decrease, thereby reducing losses. At the same time, the secondary feedback sampling module 500 can be disconnected, thereby disconnecting unnecessary output voltage sampling feedback loops, reducing the losses of the secondary feedback sampling module 500, and thus reducing standby power consumption.

[0068] Please see Figure 2 In some embodiments, the first switching module 100 includes: a first resistor R1, a second resistor R2, a first transistor V1, and a second transistor V2. One end of the first resistor R1 is connected to the standby control signal; the other end of the first resistor R1 is connected to one end of the second resistor R2 and the base of the first transistor V1; the other end of the second resistor R2 is grounded; the collector of the first transistor V1 is connected to the base of the second transistor V2, and the emitter of the first transistor V1 is grounded; the collector of the second transistor V2 is connected to the second switching module 200 and the buck module 400, respectively, and the emitter of the second transistor V2 is connected to the main feedback sampling module 300 and the voltage regulator module 600, respectively.

[0069] Furthermore, the second switching module 200 includes a third transistor; wherein the base of the third transistor is connected to the collector of the second transistor V2 and the step-down module 400, the collector of the third transistor V3 is connected to the secondary feedback sampling module 500, and the emitter of the third transistor is connected to the main feedback sampling module 300 and the voltage regulator module 600.

[0070] Specifically, both the first transistor V1 and the second transistor V2 are N-type transistors. When the standby control signal is a high-level signal, the first transistor V1 is turned on, pulling down the base voltage of the second transistor V2, causing the second transistor V2 to be in a turned-off state. At this time, the third transistor is turned on, and both the main feedback sampling module 300 and the secondary feedback sampling module 500 normally perform the output voltage feedback operation.

[0071] When the standby control signal is low, the first transistor is off, and the base voltage of the second transistor V2 is the main output voltage, causing the first transistor V1 to be on. The buck module 400 is connected to the main feedback sampling module 300. Furthermore, at this time, the base-emitter voltage Ube of the third transistor V3 is equal to the collector-emitter voltage Uce of the second transistor V2, i.e., Ube = Uce. Because the collector-emitter voltage Uce of the second transistor V2 is less than the base-emitter on-state voltage of the third transistor, the third transistor is off, and the secondary feedback sampling module 500 does not participate in the feedback operation. Therefore, when the device is in standby mode, the secondary feedback sampling module 500 does not operate, thus reducing power consumption. Because the step-down module 400 participates in the sampling of the main feedback sampling module 300, the main output voltage is reduced, and the voltage value of the sampling signal fed back to the control chip is reduced, thereby reducing the voltage values ​​of the main output voltage and the secondary output voltage, and thus reducing standby power consumption.

[0072] Please see Figure 1 and Figure 2 In a further embodiment of one example, the main feedback sampling module 300 includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is connected to the main output voltage and to the output module 700; the other end of the third resistor R3 is connected to the voltage regulator module 600 and one end of the fourth resistor R4; the other end of the fourth resistor R4 is grounded.

[0073] Furthermore, the step-down module 400 includes a fifth resistor R5; wherein one end of the fifth resistor R5 is connected to the main output voltage, and the other end of the fifth resistor R5 is connected to the collector of the second transistor V2.

[0074] The secondary feedback sampling module 500 includes a sixth resistor; wherein one end of the sixth resistor is connected to the secondary output voltage, and the other end of the sixth resistor is connected to the collector of the third transistor.

[0075] Specifically, when the standby control signal is high, the device is working normally. The fifth resistor R5 does not participate in the feedback, while the third resistor R4, the fourth resistor R5, and the sixth resistor participate in the feedback of the output voltage. At this time, both the main output voltage and the secondary output voltage are at normal operating voltage and participate in the feedback. The output voltages of the transformer are in a good cross-adjustment state.

[0076] When the standby control signal is low, the second transistor V2 is turned on, the third switch V3 is turned off, and the fifth resistor R5 participates in the sampling of the main output voltage. The feedback resistor of the main output voltage is the resistance value of the third resistor R3 and the fifth resistor R5 connected in parallel. The sixth resistor does not participate in the sampling of the secondary output voltage, that is, it does not sample the secondary output voltage. Therefore, it can shut down part of the output voltage sampling feedback line and reduce the standby output voltage, thereby achieving the purpose of reducing standby power consumption.

[0077] Please continue reading. Figure 1 and Figure 2 In a further embodiment of one example, the output module 700 includes: a seventh resistor R7, an eighth resistor R8, and an optocoupler N2; wherein, one end of the seventh resistor R7 is connected to the main output voltage, and the other end of the seventh resistor R7 is connected to the first pin of the optocoupler N2 and one end of the eighth resistor R8; the other end of the eighth resistor R8 is connected to the second pin of the optocoupler N2; the second pin of the optocoupler N2 is also connected to the voltage regulator module 600, the third pin of the optocoupler N2 is connected to the ground pin of the control chip, and the fourth pin of the optocoupler N2 is connected to the feedback pin of the control chip.

[0078] Further, the voltage regulator module 600 includes: a three-terminal voltage regulator N1, a ninth resistor R9, a first capacitor C1, and a second capacitor C2. The cathode of the three-terminal voltage regulator N1 is connected to the second pin of the optocoupler N2; the ninth resistor R9 and the first capacitor C1 are connected in series and then in parallel between the cathode and the reference terminal of the three-terminal voltage regulator N1; the second capacitor C2 is connected in parallel between the cathode and the reference terminal of the three-terminal voltage regulator N1; and the anode of the three-terminal voltage regulator N1 is grounded.

[0079] Specifically, the three-terminal regulator N1 is a three-terminal regulator integrated circuit. In one implementation, a TL431 three-terminal regulator can be used. Pin 1 of this three-terminal regulator is the reference terminal, and pin 1 is connected to a constant voltage Vref. The seventh resistor R7 is connected to the main output voltage and serves as a current-limiting resistor. The eighth resistor R8 is a voltage divider resistor. The ninth resistor R9, the first capacitor C1, and the second capacitor C2 form a second-order network, a compensation feedback loop, which provides the feedback network with higher gain margin and phase margin, resulting in a more stable output.

[0080] When the output voltage increases, the voltage across the reference input terminal (internally equivalent to the inverting input terminal of an error amplifier) ​​of the three-terminal regulator N1, after being divided by the third resistor R3, the sixth resistor, and the fourth resistor R4, increases. This voltage is compared with the internal reference voltage of 2.5V of the three-terminal regulator N1, causing the voltage between the anode and cathode of the three-terminal regulator N1 to decrease. Consequently, the current in the optocoupler diode (pins 1 and 2) of the optocoupler N2 increases, thus reducing the dynamic resistance between the collector and emitter of the optocoupler diode and lowering the voltage between the collector and emitter (pins 3 and 4). This results in a lower level at the feedback pin of the PWM control chip. The PWM chip adjusts the frequency or duty cycle of the switching circuit drive, thereby regulating the magnitude of the secondary output voltage (main output voltage and secondary output voltage) of the transformer.

[0081] Since the number of the secondary feedback sampling modules 500 corresponds to the number of secondary output voltage channels of the transformer, the number of the sixth resistors also corresponds to the number of secondary output voltage channels of the transformer.

[0082] For example, if there are two output voltages, then two sixth resistors can be set, denoted as resistor R61 and resistor R62 respectively. Resistor R61 samples the first output voltage, and resistor R62 samples the second output voltage. Two third transistors are also set, denoted as V31 and V32, as follows: Figure 2 As shown. When the standby control signal is a low-level signal, the base-to-emitter voltage Ube of transistors V31 and V32 is equal to the collector-to-emitter voltage Uce of the second transistor, i.e., Ube = Uce. Because the collector-to-emitter voltage Uce of the second transistor V2 is less than the base-to-emitter turn-on voltage of the third transistor, transistors V31 and V32 are in the off state. Resistors R61 and R62 do not participate in the secondary output voltage sampling feedback, thus reducing the losses of resistors R61 and R62. The reduced losses can be calculated using the following formula:

[0083] (secondary output voltage 1 - Vref)2 / R61 + (secondary output voltage 2 - Vref)2 / R62;

[0084] It is evident that a higher output voltage can significantly reduce standby power consumption.

[0085] Please see Figure 1 and Figure 3 In some embodiments, the second switching module 200 includes: a fourth transistor V4 and a diode; wherein the base of the fourth transistor V4 is connected to the collector of the second transistor V2 and the step-down module 400, the collector of the fourth transistor V4 is connected to the cathode of the diode, and the emitter of the fourth transistor V4 is connected to the main feedback sampling module and the voltage regulator module 600; the anode of the diode is connected to the secondary feedback sampling module 500.

[0086] Specifically, the secondary feedback sampling module 500 can be connected to the fourth transistor via the diode, so that when the fourth transistor V4 is turned off in standby mode, the secondary output voltage sampling line is disconnected. Replacing the transistor with a diode reduces the circuit board layout area, thereby reducing costs. Figure 3 As shown, resistors R61 and R62 are connected via diodes D1 and D2, respectively.

[0087] Please see Figure 4 In some embodiments, multiple diodes can be packaged together to form diode D3. This reduces the number of devices and the layout area of ​​the traces when outputting multiple voltages, thereby reducing costs.

[0088] Please see Figure 5 In some embodiments, the present invention also provides a multi-output voltage sampling feedback method applied to the multi-output voltage sampling feedback circuit described above, which includes the following steps:

[0089] S100. When the standby control signal is a high-level signal, the first switching module controls the second switching module to turn on, and both the main feedback sampling module and the secondary feedback sampling module participate in the feedback sampling of the output voltage; as described in an embodiment of a switching power supply, it will not be repeated here.

[0090] S200. When the standby control signal is a low-level signal, the first switching module controls the second switching module to turn off and connect the buck module and the main feedback sampling module, so as to reduce the main output voltage and disconnect the secondary feedback sampling module at the same time. This is specifically described in an embodiment of a switching power supply, and will not be repeated here.

[0091] In summary, the multi-channel output voltage sampling feedback circuit, method, and switching power supply provided by this invention, by setting a second switching module between the output module and the first switching module, when the standby control signal is a low-level signal, the second switching module is controlled to open by the first switching module, and the buck module is connected to the main feedback sampling module. In this way, the secondary feedback sampling module can be disconnected while reducing the main output voltage, thereby disconnecting the unnecessary output voltage sampling feedback loop and thus reducing standby power consumption.

[0092] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A multi-channel output voltage sampling feedback circuit, characterized in that, include: The system comprises a first switching module, a second switching module, a main feedback sampling module, a step-down module, at least one secondary feedback sampling module, a voltage regulator module, and an output module; wherein... The first switch module receives a standby control signal and is connected to the second switch module, the main feedback sampling module, the step-down module, and the voltage regulator module respectively. The first switch module is used to control the second switch module to turn on or off, and to control the main feedback sampling module and the step-down module to be connected and disconnected. The second switching module is connected to the first switching module, the main feedback sampling module, the step-down module, the secondary feedback sampling module, and the voltage regulator module, respectively. The second switching module is used to control the on / off connection between the secondary feedback sampling module and the voltage regulator module. The main feedback sampling module is used to acquire the main output voltage; the secondary feedback sampling module is used to acquire the secondary output voltage. The step-down module is connected to the main output voltage and is connected to the first switching module. The step-down module is used to reduce the value of the main output voltage. The output module is connected to the main feedback sampling module and the voltage regulation module respectively, and the output module is used to output the sampling signal; The voltage regulator module is connected to the main feedback sampling module, the first switch module, the second switch module and the output module respectively, and the voltage regulator module is used to stabilize the magnitude of the sampling signal.

2. The multi-channel output voltage sampling feedback circuit according to claim 1, characterized in that, The first switching module includes: a first resistor, a second resistor, a first transistor, and a second transistor; wherein, One end of the first resistor is connected to the standby control signal, and the other end of the first resistor is connected to one end of the second resistor and the base of the first transistor; The other end of the second resistor is grounded; The collector of the first transistor is connected to the base of the second transistor, and the emitter of the first transistor is grounded. The collector of the second transistor is connected to the second switching module and the buck module, respectively, and the emitter of the second transistor is connected to the main feedback sampling module and the voltage regulator module, respectively.

3. The multi-channel output voltage sampling feedback circuit according to claim 2, characterized in that, The second switching module includes: a third transistor; wherein, The base of the third transistor is connected to the collector of the second transistor and the step-down module, the collector of the third transistor is connected to the secondary feedback sampling module, and the emitter of the third transistor is connected to the main feedback sampling module and the voltage regulator module.

4. The multi-channel output voltage sampling feedback circuit according to claim 2, characterized in that, The second switching module includes: a fourth transistor and a diode; wherein, The base of the fourth transistor is connected to the collector of the second transistor and the step-down module, the collector of the fourth transistor is connected to the cathode of the diode, and the emitter of the fourth transistor is connected to the main feedback sampling module and the voltage regulation module. The anode of the diode is connected to the secondary feedback sampling module.

5. The multi-channel output voltage sampling feedback circuit according to claim 2, characterized in that, The main feedback sampling module includes: a third resistor and a fourth resistor; wherein... One end of the third resistor is connected to the main output voltage and to the output module, and the other end of the third resistor is connected to the voltage regulator module and one end of the fourth resistor, respectively. The other end of the fourth resistor is grounded; The step-down module includes: a fifth resistor; wherein... One end of the fifth resistor is connected to the main output voltage, and the other end of the fifth resistor is connected to the collector of the second transistor.

6. The multi-channel output voltage sampling feedback circuit according to claim 3, characterized in that, The secondary feedback sampling module includes: a sixth resistor; wherein... One end of the sixth resistor is connected to the secondary output voltage, and the other end of the sixth resistor is connected to the collector of the third transistor.

7. The multi-channel output voltage sampling feedback circuit according to claim 1, characterized in that, The output module includes: a seventh resistor, an eighth resistor, and an optocoupler; wherein... One end of the seventh resistor is connected to the main output voltage, and the other end of the seventh resistor is connected to the first pin of the optocoupler and one end of the eighth resistor, respectively. The other end of the eighth resistor is connected to the second pin of the optocoupler; The second pin of the optocoupler is also connected to the voltage regulator module, the third pin of the optocoupler is connected to the ground pin of the control chip, and the fourth pin of the optocoupler is connected to the feedback pin of the control chip.

8. The multi-channel output voltage sampling feedback circuit according to claim 7, characterized in that, The voltage regulator module includes: a three-terminal voltage regulator, a ninth resistor, a first capacitor, and a second capacitor; wherein... The cathode of the three-terminal voltage regulator is connected to the second pin of the optocoupler; The ninth resistor is connected in series with the first capacitor and then in parallel between the cathode and the reference terminal of the three-terminal voltage regulator. The second capacitor is connected in parallel between the cathode and the reference terminal of the three-terminal regulator; The anode of the three-terminal voltage regulator is grounded.

9. A switching power supply, characterized in that, It includes a control chip, a transformer for outputting multiple output voltages, and a multiple output voltage sampling feedback circuit as described in any one of claims 1-8; wherein, The multi-output voltage feedback circuit is connected to the control chip and is used to collect the multi-output voltage output by the transformer. The control chip is connected to the multi-channel output voltage sampling feedback circuit and the transformer, respectively, and is used to adjust the output voltage of the transformer according to the sampling signal fed back by the multi-channel output voltage feedback circuit.

10. A multi-channel output voltage sampling feedback method applied to the multi-channel output voltage sampling feedback circuit according to any one of claims 1-8, characterized in that, include: When the standby control signal is a high-level signal, the first switch module controls the second switch module to turn on, and both the main feedback sampling module and the secondary feedback sampling module participate in the feedback sampling of the output voltage. When the standby control signal is a low level signal, the first switch module controls the second switch module to turn off and connect the buck module and the main feedback sampling module, so as to reduce the main output voltage and disconnect the secondary feedback sampling module at the same time.

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