Multipath output circuit and switching power supply

Abstract

The invention belongs to the technical field of power supply circuits, and particularly discloses a multi-path output circuit and a switching power supply. The transformer comprises a primary winding and a secondary winding which are mutually coupled, the primary winding is used for inputting voltage and is grounded through the switch unit, the secondary winding comprises a first output node and at least one second output node, the output voltage of the first output node is smaller than that of the second output node, and the first output node is connected to a common node; the second output node is connected to the common node through the step-down circuit, the first feedback circuit is connected with the common node and used for outputting a feedback signal based on the voltage of the common node, and the controller is connected with the first feedback circuit and the switch unit and used for driving the switch unit based on the feedback signal. According to the multi-path output circuit, the first output node and the second output node share the first feedback circuit to realize voltage stabilization control, so that the complexity of the multi-path output circuit is reduced, and the circuit structure is simplified.

Description

Technical Field

[0001] This application relates to the field of power supply circuit technology, and in particular to a multi-output circuit and a switching power supply. Background Technology

[0002] In electronic systems, all integrated circuits and components require a stable and clean supply voltage to function properly. Voltage fluctuations can lead to degraded performance, malfunctions, or even damage. Voltage regulation is an automatic adjustment system used to maintain a constant output voltage when the input voltage and load current change.

[0003] In related technologies, when a power supply system provides multiple different voltages, such as +12V for fans and motors, and +5V for logic circuits, there are usually multiple voltage regulation control circuits, which leads to circuit complexity. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a multi-output circuit and a switching power supply, enabling the first output node and the second output node to share a first feedback circuit for voltage regulation control, thereby reducing the complexity of the multi-output circuit and simplifying the circuit structure.

[0005] The multi-output circuit of this application embodiment includes: A transformer includes a primary winding and a secondary winding coupled to each other. The primary winding is used for input voltage and grounded through a switching unit. The secondary winding includes a first output node and at least one second output node. The output voltage of the first output node is less than the output voltage of the second output node. The first output node is connected to a common node, and the second output node is connected to the common node through a step-down circuit. A first feedback circuit, connected to the common node, is used to output a feedback signal based on the voltage of the common node; The controller is connected to the first feedback circuit and the switching unit, and is used to drive the switching unit based on the feedback signal.

[0006] In some embodiments, the first feedback circuit includes: A first voltage sampling circuit is connected to the common node; The first comparator includes a first input terminal, a second input terminal, and a first output terminal. The first input terminal is connected to the first voltage sampling circuit, and the second input terminal is used to input a first reference voltage. The optocoupler includes a first input side, a second input side, a first output side, and a second output side. The first input side is connected to the first output node of the secondary winding, the second input side is connected to the first output terminal, the first output side is grounded, and the second output side is connected to the controller.

[0007] In some embodiments, the first voltage sampling circuit includes a first resistor and a second resistor, a first end of the first resistor is connected to the common node, a second end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is grounded, and the first input terminal is connected between the first resistor and the second resistor.

[0008] In some embodiments, the first feedback circuit further includes a first diode, the anode of which is connected to the second input side, and the cathode of which is connected to the first output terminal.

[0009] In some embodiments, the step-down circuit includes: A reference voltage circuit is connected between the second output node and the common node; A voltage regulator, comprising a reference terminal, an anode terminal, and a cathode terminal, wherein the reference terminal is connected to the reference voltage circuit, the anode terminal is connected to the common node, and the cathode terminal is connected to the second output node.

[0010] In some embodiments, the reference voltage circuit includes a third resistor and a fourth resistor, one end of the third resistor is connected to the second output node, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to the common node, and the reference terminal of the regulator is connected between the third resistor and the fourth resistor.

[0011] In some embodiments, the multiplexed output circuit further includes a second feedback circuit, the second feedback circuit comprising: The second voltage sampling circuit is connected to the first output node and the second output node and grounded; The second comparator includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the second voltage sampling circuit, and the fourth input terminal is used to input a second reference voltage. The second output terminal is connected to the cathode of the first diode.

[0012] In some embodiments, the second voltage sampling circuit includes a fifth resistor and a sixth resistor. One end of the fifth resistor is connected to the first output node and the second output node, and the other end of the fifth resistor is grounded. One end of the sixth resistor is connected between the fifth resistor and the first output node and the second output node, and the other end of the sixth resistor is connected to the third input terminal.

[0013] In some embodiments, the output voltage of the first output node is 5V, and there are three second output nodes, with the output voltages of the three second output nodes being 9V, 12V, and 15V, respectively.

[0014] The switching power supply of this application includes the multi-output circuit described in any of the above embodiments.

[0015] In this embodiment of the multi-output circuit, the first feedback circuit is connected to a common node, and the controller controls the switching unit to adjust the input voltage of the primary winding. This ensures that the output voltages of the first and second output nodes remain constant due to the influence of the input voltage, thereby achieving voltage feedback regulation of the multi-output circuit and achieving voltage stabilization. The buck circuit reduces the output voltage of at least one second output node to match the output voltage of the first output node, unifying the voltage of the common node. Then, the first feedback circuit is shared to achieve voltage stabilization control. This reduces the number of first feedback circuits required, lowers the complexity of the multi-output circuit, simplifies the circuit structure, and saves costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a multi-output circuit according to an embodiment of this application.

[0018] Figure 2 This is a circuit example diagram of a multi-output circuit according to an embodiment of this application. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] The following is combined Figure 1 and Figure 2 This application describes a multi-output circuit and a switching power supply according to embodiments of the present application.

[0021] refer to Figure 1This application provides a multi-output circuit. The multi-output circuit has a step-down circuit 40, which can reduce the output voltage of the second output node 20 to be consistent with the output voltage of the first output node 10, so as to facilitate the use of the first feedback circuit 50 to achieve voltage regulation control, thereby reducing the complexity of the multi-output circuit.

[0022] The multi-output circuit includes a transformer T, a first feedback circuit 50, and a controller 60.

[0023] The transformer T includes a primary winding Na and a secondary winding Ns, which are coupled together. The primary winding Na is used for the input voltage and is grounded through the switching unit 70. In this embodiment, the switching unit 70 can be a MOSFET, which controls the magnitude of the input voltage to the primary winding Na. For example, when the duty cycle of the MOSFET increases, the input voltage increases; when the duty cycle of the MOSFET decreases, the input voltage decreases.

[0024] The secondary winding Ns includes a first output node 10 and at least one second output node 20, wherein the output voltage of the first output node 10 is less than the output voltage of the second output node 20.

[0025] In this embodiment, the first output node 10 outputs 5V, and there are three second output nodes 20, with output voltages of 9V, 12V, and 15V respectively. It can be understood that a 5V output voltage can power devices such as logic chips, USB ports, and solid-state drives on the motherboard. A 9V output voltage can power devices such as radios, walkie-talkies, multimeters, and guitar effects pedals. A 12V output voltage can power devices such as CPUs, GPUs, hard drive motors, and chassis fans. A 15V output voltage can power devices such as analog-to-digital converters and operational amplifiers. Different output voltages are suitable for different electrical devices, achieving multi-output and multi-power supply.

[0026] The first output node 10 is connected to the common node 30, and the second output node 20 is connected to the common node 30 through a step-down circuit 40. The step-down circuit 40 is used to reduce the output voltage of the second output node 20 to be the same as the output voltage of the first output node 10, that is, the voltage on the common node 30 is uniform, both being 5V.

[0027] The first feedback circuit 50 is connected to the common node 30 and is used to output a feedback signal based on the voltage of the common node 30. In practical applications, the feedback signal can be a voltage signal.

[0028] The controller 60 is connected to the first feedback circuit 50 and the switching unit 70, and is used to drive the switching unit 70 based on the feedback signal.

[0029] The controller 60 can directly use a PWM chip. The controller 60 is used to drive the switching unit 70, i.e., the MOSFET, based on the feedback signal to adjust the input voltage of the primary winding Na, thereby keeping the output voltage of the first output node 10 and the second output node 20 constant. This achieves voltage regulation control of the multi-output circuit.

[0030] In this embodiment of the multi-output circuit, the first feedback circuit 50 is connected to the common node 30, and the controller 60 controls the switching unit 70 to adjust the input voltage of the primary winding Na. This ensures that the output voltages of the first output node 10 and the second output node 20 remain constant due to the influence of the input voltage, thereby achieving voltage feedback regulation of the multi-output circuit and achieving voltage stabilization. The buck circuit 40 reduces the output voltage of at least one second output node 20 to match the output voltage of the first output node 10, unifying the voltage of the common node 30. Then, the first feedback circuit 50 is shared to achieve voltage stabilization control. This reduces the number of first feedback circuits 50, lowers the complexity of the multi-output circuit, simplifies the circuit structure, and saves costs.

[0031] refer to Figure 2 In some embodiments, the first feedback circuit 50 includes a first voltage sampling circuit, a first comparator U1, and an optocoupler U3.

[0032] The first voltage sampling circuit is connected to a common node 30. In some embodiments, the first voltage sampling circuit includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the common node 30, the second end of the first resistor R1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is grounded.

[0033] The first comparator U1 includes a first input terminal 11, a second input terminal 12, and a first output terminal 13. The first input terminal 11 is connected to a first voltage sampling circuit, for example, the first input terminal 11 is connected between a first resistor R1 and a second resistor R2. The second input terminal 12 is used to input a first reference voltage. In one example, the first reference voltage can be 2.5V.

[0034] In practical applications, the first comparator U1 also includes a power supply terminal 14 and a ground terminal 15. The power supply terminal 14 is used to input the power supply voltage. For example, the power supply terminal 14 is connected to the common node 30 through a resistor R7. Resistor R7 has a voltage reduction function, which can reduce the voltage of the common node 30 to the power supply voltage required by the first comparator U1. Resistor R7 also limits the current, preventing excessive current from damaging the first comparator U1. The ground terminal 15 is grounded.

[0035] Optocoupler U3 includes a first input side, a second input side, a first output side, and a second output side. In practical applications, optocoupler U3 includes a light-emitting diode (LED) and a phototransistor, which are coupled to each other to realize the transmission and conversion of optical signals and electrical signals. The first and second input sides are located at the two ends of the LED, and the first and second output sides are located at the two ends of the phototransistor.

[0036] The first input side is the positive terminal of the LED, and is connected to the first output node 10 of the secondary winding Ns. The second input side is the negative terminal of the LED, and is connected to the first output terminal 13 of the first comparator U1. The first output side can be the emitter of a phototransistor, and is grounded. The second output side can be the collector of a phototransistor, and is connected to the controller 60.

[0037] refer to Figure 2 In some embodiments, the first feedback circuit 50 further includes a first diode D1, the anode of which is connected to the second input side. The cathode of the first diode D1 is connected to the first output terminal 13. In this embodiment, the first diode D1 is a common anode diode with two cathodes, one of which is connected to the first output terminal 13. The second input side of the optocoupler U3 is connected to the first output terminal 13 of the first comparator U1 through the first diode D1.

[0038] refer to Figure 2 In some embodiments, the buck circuit 40 includes a reference voltage circuit and a voltage regulator D4.

[0039] The reference voltage circuit is connected between the second output node 20 and the common node 30. In practical applications, the reference voltage circuit includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is connected to the second output node 20, the other end of the third resistor R3 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the common node 30.

[0040] The voltage regulator D4 includes a reference terminal 41, an anode terminal 42, and a cathode terminal 43. The reference terminal 41 is connected to a reference voltage circuit, for example, between the third resistor R3 and the fourth resistor R4. The anode terminal 42 is connected to a common node 30. The cathode terminal 43 is connected to the second output node 20. In this embodiment, the voltage regulator D4 can be a TL431. The voltage regulator D4, through comparison and judgment, reduces the output voltage of the second output node 20 to match the output voltage of the first output node 10, and then outputs it to the common node 30.

[0041] refer to Figure 2In some embodiments, the multiple output circuit further includes a second feedback circuit, which includes a second voltage sampling circuit and a second comparator U2.

[0042] The second voltage sampling circuit is connected to and grounded by the first output node 10 and the second output node 20. In practical applications, the second voltage sampling circuit includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is connected to the first output node 10 and the second output node 20. Notably, the first output node 10 and the second output node 20 form a common terminal downstream of the secondary winding Ns, and one end of the fifth resistor R5 is connected to this common terminal. The other end of the fifth resistor R5 is grounded. One end of the sixth resistor R6 is connected between the fifth resistor R5 and the first output node 10 and the second output node 20; in other words, one end of the sixth resistor R6 is connected between the fifth resistor R5 and the aforementioned common terminal.

[0043] The second comparator U2 includes a third input terminal 21, a fourth input terminal 22, and a second output terminal 23. The third input terminal 21 is connected to a second voltage sampling circuit, for example, it is connected to the other end of a sixth resistor R6. The fourth input terminal 22 is used to input a second reference voltage. In one example, the second reference voltage is 2.5V. The second output terminal 23 is connected to the other cathode of the first diode D1. The second output terminal 23 of the second comparator U2 is connected to the optocoupler U3 through the first diode D1.

[0044] refer to Figure 2 In some embodiments, the multiplexed output circuit further includes a second diode D2 and a third diode D3.

[0045] The second diode D2 is connected in series between the first output node 10 and the secondary winding Ns. Specifically, the anode of the second diode D2 is connected to the secondary winding Ns, and the cathode of the second diode D2 is connected to the first output node 10.

[0046] The third diode D3 is connected in series between the second output node 20 and the secondary winding Ns. Specifically, the anode of the third diode D3 is connected to the secondary winding Ns, and the cathode of the third diode D3 is connected to the second output node 20. It can be understood that when there are multiple second output nodes 20, the number of third diodes D3 is equal to the number of second output nodes 20 and they correspond one-to-one.

[0047] refer to Figure 1 and Figure 2 The working principle of the multi-output circuit in this application embodiment is as follows: When the output voltage of the first output node 10 increases, for example, above the set voltage of 5V, the voltage after the voltage division by the first resistor R1 and the second resistor R2 is higher than 2.5V. That is, the voltage at the first input terminal 11 is higher than 2.5V, which is higher than the first reference voltage at the second input terminal 12. The first output terminal 13 outputs a low voltage, equivalent to grounding. The conduction current of the light-emitting diode (LED) increases, and the light intensity of the LED increases. Under the influence of the light intensity of the LED, the photocurrent of the phototransistor also increases. The phototransistor lowers the feedback pin voltage of the PWM chip, and the PWM chip controls the MOSFET to reduce the duty cycle, thereby reducing the input voltage of the primary winding Na, and consequently reducing the output voltage of the first output node 10 of the secondary winding Ns. This keeps the output voltage of the first output node 10 stable at the set voltage.

[0048] Conversely, when the output voltage of the first output node 10 decreases, for example, when it is lower than the set voltage of 5V, the above process is reversed, eventually causing the output voltage of the first output node 10 to rise and stabilize at the set voltage.

[0049] Therefore, the above process can achieve voltage regulation control of the output voltage of the first output node 10.

[0050] When the output voltage of the second output node 20 increases, for example, above the set voltage, it should be noted that when there are multiple second output nodes 20, their output voltages are different, and the corresponding set voltages are also different. When the output voltage is higher than the corresponding set voltage, the output voltage is first stepped down by the buck circuit 40, and at the common node 30, it is kept basically consistent with the output voltage of the first output node 10. Then, consistent with the feedback path of the output voltage of the first output node 10, the MOSFET is finally controlled to reduce the duty cycle, so that the input voltage of the primary winding Na decreases, thereby causing the output voltage of the second output node 20 to fall back and stabilize at the corresponding set voltage.

[0051] Conversely, when the output voltage of the second output node 20 decreases, for example, when it falls below the corresponding set voltage, the above process reverses, eventually causing the output voltage of the second output node 20 to rise and stabilize at the corresponding set voltage.

[0052] Therefore, the above process can achieve voltage regulation control of the output voltage of the second output node 20.

[0053] Therefore, the multi-output circuit of this application embodiment reduces the output voltage of at least one second output node 20 to be consistent with the output voltage of the first output node 10 through the step-down circuit 40, and then uses the first feedback circuit 50 to achieve voltage regulation control, thereby reducing the complexity of the multi-output circuit, simplifying the circuit structure, and saving costs.

[0054] Based on the second feedback circuit, when the output voltage of the first output node 10 and / or the second output node 20 is higher than the set voltage, the output current increases. The voltage drop across the fifth resistor R5 increases accordingly, and the voltage at the third input terminal 21 of the second comparator U2 also increases. When the voltage at the third input terminal 21 is higher than the second reference voltage, the second output terminal 23 outputs a low voltage, equivalent to grounding. Simultaneously, the first output terminal 13 of the first comparator U1 also outputs a low voltage, equivalent to grounding. At this time, the conduction current of the LED is greater, the light intensity of the LED is greater, and the photocurrent of the phototransistor is also greater. This reduces the duty cycle of the MOSFET controlled by the PWM chip, thereby reducing the input voltage of the primary winding Na and the output voltage of the secondary winding Ns. Thus, when the output current increases, the output voltage decreases, limiting the output power of the multi-output circuit and achieving a power limiting effect.

[0055] If the voltage at the third input terminal 21 of the second comparator U2 is lower than the second reference voltage, the second output terminal 23 outputs a high voltage. Due to the unidirectional conductivity of the first diode D1, the feedback process of the optocoupler U3 is not controlled by the second feedback circuit.

[0056] refer to Figure 1 This application also proposes a switching power supply, including the multi-output circuit of any of the above embodiments.

[0057] The technical advantages of the switching power supply in this application embodiment are the same as those of the multi-output circuit in this application embodiment, and will not be repeated here.

[0058] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0059] It should be noted that, in the embodiments of this application, "electrical connection" can be a direct connection between two electrical components or an indirect connection. For example, the electrical connection between A and B can be achieved by A and B being directly connected, or by A and B being indirectly connected through one or more other electrical components.

[0060] The multi-output circuit and switching power supply provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A multiple output circuit, characterized by comprising: include: A transformer includes a primary winding and a secondary winding coupled to each other. The primary winding is used for input voltage and grounded through a switching unit. The secondary winding includes a first output node and at least one second output node. The output voltage of the first output node is less than the output voltage of the second output node. The first output node is connected to a common node, and the second output node is connected to the common node through a step-down circuit. A first feedback circuit, connected to the common node, is used to output a feedback signal based on the voltage of the common node; The controller is connected to the first feedback circuit and the switching unit, and is used to drive the switching unit based on the feedback signal.

2. The multiple output circuit of claim 1, wherein, The first feedback circuit includes: A first voltage sampling circuit is connected to the common node; The first comparator includes a first input terminal, a second input terminal, and a first output terminal. The first input terminal is connected to the first voltage sampling circuit, and the second input terminal is used to input a first reference voltage. The optocoupler includes a first input side, a second input side, a first output side, and a second output side. The first input side is connected to the first output node of the secondary winding, the second input side is connected to the first output terminal, the first output side is grounded, and the second output side is connected to the controller.

3. The multiple output circuit of claim 2, wherein, The first voltage sampling circuit includes a first resistor and a second resistor. The first end of the first resistor is connected to the common node, the second end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is grounded, and the first input terminal is connected between the first resistor and the second resistor.

4. The multiple output circuit of claim 2, wherein, The first feedback circuit further includes a first diode, the anode of which is connected to the second input side, and the cathode of which is connected to the first output terminal.

5. The multiple output circuit according to any one of claims 1 to 4, wherein The step-down circuit includes: A reference voltage circuit is connected between the second output node and the common node; A voltage regulator, comprising a reference terminal, an anode terminal, and a cathode terminal, wherein the reference terminal is connected to the reference voltage circuit, the anode terminal is connected to the common node, and the cathode terminal is connected to the second output node.

6. The multiple output circuit of claim 5, wherein, The reference voltage circuit includes a third resistor and a fourth resistor. One end of the third resistor is connected to the second output node, and the other end of the third resistor is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to the common node. The reference terminal of the voltage regulator is connected between the third resistor and the fourth resistor.

7. The multiple output circuit of claim 2, wherein, It also includes a second feedback circuit, which includes: The second voltage sampling circuit is connected to the first output node and the second output node and grounded; The second comparator includes a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal is connected to the second voltage sampling circuit, and the fourth input terminal is used to input a second reference voltage. The second output terminal is connected to the cathode of the first diode.

8. The multiple output circuit of claim 7, wherein, The second voltage sampling circuit includes a fifth resistor and a sixth resistor. One end of the fifth resistor is connected to the first output node and the second output node, and the other end of the fifth resistor is grounded. One end of the sixth resistor is connected between the fifth resistor and the first output node and the second output node, and the other end of the sixth resistor is connected to the third input terminal.

9. The multiple output circuit according to any one of claims 1 to 4, wherein The first output node has an output voltage of 5V, and there are three second output nodes, with output voltages of 9V, 12V, and 15V respectively.

10. A switching power supply, characterized in that, Includes the multi-output circuit as described in any one of claims 1 to 9.

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