Multipath output flyback conversion circuit, chip and electronic equipment

Abstract

The invention relates to the technical field of switching power supplies, in particular to a multi-output flyback conversion circuit, a chip and electronic equipment. The multi-output flyback conversion circuit comprises a primary control circuit, a secondary control circuit, a transformer, a primary transistor, a load detection circuit, a voltage sampling circuit, a voltage regulation circuit and at least two discharge branches. When only one electronic device is connected into the multiple discharge branches, namely the multiple output flyback conversion circuit is in a single output mode, the voltage of the other no-load discharge branches is adjusted to be the same as the voltage of the branch connected into the load, and therefore the voltage impact on the discharge branches can be reduced; besides, when all the discharge branches are in a normally-on state, the capacitors on the discharge branches are connected in parallel and bear load energy together, so that the stress of the switching devices and the capacitors on the discharge branches is reduced, the switching devices and the capacitors are prevented from being damaged due to overlarge stress, and the service life of the multi-path output flyback conversion circuit is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a multi-channel output flyback conversion circuit, a chip and an electronic device. Background Art

[0002] With the development of electronic technology, various types of electronic devices emerge in an endless stream. Different types of electronic devices may have different types of charging interfaces. In order to meet the charging needs of electronic devices with different interface types, the power adapter can usually be set with two or more different charging interfaces, and each charging interface corresponds to a discharge branch, so that electronic devices with different charging interfaces can be charged at the same time. Among them, different electronic devices include different loads, so when multiple electronic devices are charged at the same time, the charging voltage output by each discharge branch will generally be different. In order to meet the charging needs of multiple electronic devices at the same time, the flyback multi-output converter came into being, which has the advantages of small size and low cost.

[0003] The dual-output flyback converter in the related art usually includes two discharge branches. When one of the discharge branches is in a no-load state, the flyback converter becomes a single-output. At this time, the load of the circuit is entirely borne by one discharge branch, resulting in a large load rate of the discharge branch. This will increase the stress of the switching devices and energy storage devices in the discharge branch, affecting the working life of the switching devices and the energy storage devices, thereby resulting in a shorter working life of the flyback converter. Summary of the invention

[0004] The present application provides a multi-channel output flyback conversion circuit, a chip and an electronic device to solve the technical problem of a short working life of a flyback converter in the related art.

[0005] In a first aspect, the present application provides a multi-output flyback conversion circuit, including: a primary control circuit, a secondary control circuit, a transformer, a primary transistor, a load detection circuit, a voltage sampling circuit, a voltage regulation circuit, and at least two discharge branches;

[0006] The first end of the primary winding of the transformer is used to receive the supply voltage, the second end of the primary winding is connected to the first electrode of the primary transistor, the second electrode of the first transistor is grounded, and the control electrode of the first transistor is connected to the primary control circuit; the first end of the secondary winding of the transformer is connected to the input end of the discharge branch, the second end of the secondary winding is grounded, and the output end of the discharge branch is used to output the discharge voltage;

[0007] The discharge branch includes a switch circuit and a first capacitor, wherein the switch circuit is arranged between an input end and an output end of the discharge branch, a first end of the first capacitor is connected to the discharge branch, and a second end of the first capacitor is grounded; the secondary control circuit is connected to the switch circuit and is used to control the on and off of the switch circuit;

[0008] The sampling ends of the load detection circuit and the voltage sampling circuit are both connected to the output end of the discharge branch. The load detection circuit is used to detect whether there is a load connected to the output end of the discharge branch, and output the load detection result to the voltage regulation circuit; the voltage sampling circuit is used to sample the voltage value of the output end of each discharge branch, and output the voltage sampling result to the voltage regulation circuit;

[0009] The voltage regulating circuit is used to determine, according to the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a first regulating signal to the secondary control circuit;

[0010] The secondary control circuit is used to first adjust the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch according to the first adjustment signal, and then control the switch circuit to be turned on so that all discharge branches are in the on state.

[0011] In a possible design, the discharge branch further includes a voltage-lowering branch, an input end of the voltage-lowering branch is connected to an output end of the discharge branch, and an output end of the voltage-lowering branch is grounded;

[0012] The voltage regulating circuit is further used to determine, based on the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are higher than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a second regulating signal to the corresponding voltage lowering branch;

[0013] The voltage lowering branch is used to lower the voltage value on the corresponding discharge branch to the same value as that of the target discharge branch according to the second adjustment signal.

[0014] In a possible design, when only one target discharge branch among all the discharge branches is connected to the load, and a voltage value of the remaining discharge branches is higher than the voltage value of the target discharge branch, and a voltage value of the remaining discharge branches is lower than the voltage value of the target discharge branch;

[0015] The secondary control circuit is also used to first increase the voltage value of the corresponding discharge branch to the same value as the voltage value of the target discharge branch according to the first adjustment signal; the voltage lowering branch is also used to first lower the voltage value on the corresponding discharge branch to the same value as the target discharge branch according to the second adjustment signal, and then the secondary control circuit is also used to control all discharge branches to be turned on.

[0016] In a possible design, the discharge branch further includes a load switch; a first end of the load switch is connected to a first end of the first capacitor, a second end of the load switch is an output end of the discharge branch, and a control end of the load switch is connected to a voltage regulation circuit;

[0017] The voltage regulating circuit is further used to control the load switch to turn on when it is detected that a load is connected to the output end of the discharge branch, and to control the load switch to turn off when it is detected that no load is connected to the output end of the discharge branch.

[0018] In a possible design, the discharge branch further includes a third capacitor, a first end of the third capacitor is connected to the second end of the load switch, and a second end of the third capacitor is grounded.

[0019] In one possible design, the switch circuit includes a first transistor and a second transistor;

[0020] The first electrode of the first transistor is connected to the first end of the secondary winding, the second electrode of the first transistor is connected to the second electrode of the second transistor, and the first electrode of the second transistor is connected to the first end of the first capacitor; the control electrodes of the first transistor and the second transistor are both connected to the secondary control circuit;

[0021] The secondary control circuit is used to control the on and off of the first transistor and the second transistor.

[0022] In a possible design, the voltage regulating circuit is further used to output a third regulating signal to the secondary control circuit when it is determined that a load is connected to the output ends of at least two discharge branches according to the load detection result and the voltage sampling result;

[0023] The secondary control circuit is further used to control the conduction time ratio of the switch circuit on the discharge branch with load access according to the third adjustment signal, so as to adjust the discharge power of the output end of each discharge branch.

[0024] In a possible design, after the secondary control circuit controls all the discharge branches to be in an on state, the primary control circuit is further used to control the on-time ratio of the primary transistor to control the discharge power output by the discharge branch.

[0025] In a second aspect, the present application provides a chip, which includes a multi-output flyback conversion circuit as described in any one of the above items.

[0026] In a third aspect, the present application provides an electronic device, which includes the multi-output flyback conversion circuit as described in any one of the above items; or includes the chip as described above.

[0027] The multi-channel output flyback conversion circuit provided by the first aspect above includes: a primary control circuit, a secondary control circuit, a transformer, a primary transistor, a load detection circuit, a voltage sampling circuit, a voltage regulation circuit, and at least two discharge branches. The first end of the primary winding of the transformer is used to receive the power supply voltage, the second end of the primary winding is connected to the first electrode of the primary transistor, the second electrode of the first transistor is grounded, and the control electrode of the first transistor is connected to the primary control circuit; the first end of the secondary winding of the transformer is connected to the input end of the discharge branch, the second end of the secondary winding is grounded, and the output end of the discharge branch is used to output the discharge voltage. Each discharge branch includes a switch circuit and a first capacitor, the switch circuit is arranged between the input end and the output end of the discharge branch, the first end of the first capacitor is connected to the discharge branch, and the second end of the first capacitor is grounded; the secondary control circuit is connected to the switch circuit, and is used to control the on and off of the switch circuit; the sampling ends of the load detection circuit and the voltage sampling circuit are both connected to the output end of the discharge branch, and the output ends of the load detection circuit and the voltage sampling circuit are both connected to the voltage regulation circuit; the load detection circuit is used to detect whether there is a load connected to the output end of the discharge branch, and output the load detection result to the voltage regulation circuit; the voltage sampling circuit The secondary control circuit is used to sample the voltage value of the output end of each discharge branch and output the voltage sampling result to the voltage regulation circuit; the voltage regulation circuit is used to determine whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load according to the load detection result and the voltage sampling result, and if so, output a first regulation signal to the secondary control circuit; the secondary control circuit is used to firstly adjust the voltage value of the remaining discharge branches to the same value as the target discharge branch according to the first regulation signal, and then control the switch circuit to be turned on, so that all the discharge branches are in the on state. According to the multi-channel output flyback conversion circuit provided by the present application, when only one electronic device is connected to the multi-channel discharge branches, that is, when the multi-channel output flyback conversion circuit is a single-channel output, the voltage of the remaining unloaded discharge branches is adjusted to be the same as that of the branch connected to the load, thereby reducing the voltage impact on the discharge branch; in addition, when all discharge branches are in a normally on state, the capacitors on the multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress of the switch devices and capacitors on the discharge branches, avoiding damage to the switch devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0028] The beneficial effects provided in the above-mentioned second aspect and various possible designs of the above-mentioned second aspect can refer to the beneficial effects brought about by the above-mentioned first aspect and various possible implementation methods of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0030] Figure 1 A schematic diagram of a dual-output flyback conversion circuit provided for related technologies;

[0031] Figure 2 One of the schematic diagrams of the dual-output flyback conversion circuit structure provided in the embodiment of the present application;

[0032] Figure 3 The second schematic diagram of the dual-output flyback conversion circuit structure provided in the embodiment of the present application;

[0033] Figure 4 The third schematic diagram of the dual-output flyback conversion circuit structure provided in the embodiment of the present application;

[0034] Figure 5 A schematic diagram of the structure of the protocol chip provided in the embodiment of the present application;

[0035] Figure 6 A schematic diagram of the working process of the dual-output flyback conversion circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] In this application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c alone can represent: a, b, c, a and b, a and c, or a, b, and c, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0037] The directions or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0038] The terms "connected" and "connected" should be understood in a broad sense. For example, the "connected" or "connected" of a circuit structure can refer to not only physical connection, but also electrical connection or signal connection. For example, it can be directly connected, that is, physically connected, or indirectly connected through at least one intermediate element, as long as the circuit is connected, or it can be the internal connection of two elements; signal connection can refer to signal connection through a circuit or through a media medium, such as radio waves. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] The transistor in the present application is a three-terminal transistor, and its three terminals are a control electrode, a first electrode, and a second electrode. The transistor can be a bipolar transistor or a field effect transistor, etc. For example, when the transistor is a bipolar transistor, its control electrode refers to the base of the bipolar transistor, the first electrode can be the collector or emitter of the bipolar transistor, and the corresponding second electrode can be the emitter or collector of the bipolar transistor; when the transistor is a field effect transistor, its control electrode refers to the gate of the field effect transistor, the first electrode can be the drain or source of the field effect transistor, and the corresponding second electrode can be the source or drain of the field effect transistor.

[0040] With the development of electronic technology, the charging efficiency and charging safety of electronic devices are an issue that people are concerned about. In the related art, the switching power supply circuit for fast charging of electronic devices usually includes a transformer, a primary switch tube, a secondary switch tube, a primary control unit and a secondary control unit. Among them, the primary switch tube is arranged in the primary winding loop of the transformer, and the secondary switch tube is arranged in the secondary winding loop of the transformer. The transformer is used to convert the input power supply voltage, and then make the secondary winding output a charging voltage that is adapted to the electronic device. The primary control unit and the secondary control unit are respectively used to control the conduction or shutdown of the primary switch tube and the secondary switch tube, so as to control the switching power supply circuit to work in different charging modes to meet the charging needs of various scenarios.

[0041] At present, different types of electronic devices on the market may have different types of charging interfaces. In order to meet the charging needs of electronic devices with different interface types, the power adapter can usually be set with two or more different charging interfaces, and each charging interface corresponds to a discharge branch, so that electronic devices with different charging interfaces can be charged at the same time. For example, a fast charging adapter can realize two outputs at the same time, one output can power an electronic device with a USB Type-C interface, and the other output can charge an electronic device with a USB Type-A interface, and the two outputs can charge two electronic devices at the same time without affecting each other. Among them, different electronic devices include different loads, so when multiple electronic devices are charged at the same time, the charging voltages output by each discharge branch will generally be different.

[0042] Figure 1 For the structural diagram of the dual-output flyback conversion circuit provided for the related technology, please refer to Figure 1 As shown, the switching power supply circuit includes a first transformer T1, a primary switch tube M1 and two charging output branches. The primary switch tube M1 is arranged in the primary winding loop of the first transformer T1. Specifically, the primary switch tube M1 can be an NMOS (N-Metal-Oxide-Semiconductor) tube. The drain of the primary switch tube M1 is connected to the opposite end of the primary winding. The source of the primary switch tube M1 is grounded GND. The control electrode of the primary switch tube M1 is connected to the primary control unit. The primary control unit is used to control the conduction or shutdown of the primary switch tube M1. The same-name end of the secondary winding of the first transformer T1 is respectively connected to the input end of the two charging output branches, and the output end of the charging output branch is used to connect the load to charge the load.

[0043] Please continue to see Figure 1The dual-output flyback conversion circuit provided by the related technology includes two charging output terminals, which are respectively a first charging output terminal Vo1 and a second charging output terminal Vo2. The same-name end of the secondary winding loop of the first transformer T1 is a high-voltage end, and the same-name end of the secondary winding loop is respectively connected to the first charging output terminal Vo1 and the second charging output terminal Vo2; the opposite-name end of the secondary winding is connected to the negative electrode of the secondary diode D10, and the positive electrode of the secondary diode D10 is grounded GND. In addition, the first charging output terminal Vo1 is grounded GND through the third capacitor C1, and the second charging output terminal Vo2 is grounded GND through the fourth capacitor C2. In addition, a first switch S11 is also connected in series between the same-name end of the secondary winding loop and the first charging output terminal Vo1, and a second switch S12 is also connected in series between the same-name end of the secondary winding loop and the second charging output terminal Vo2, and the control ends of the first switch S11 and the second switch S12 are both connected to the secondary control unit. During operation, the secondary control unit controls the first switch S11 and the second switch S12 to turn on or off respectively according to the duty cycle signal, thereby controlling the energy proportion of the first charging output terminal Vo1 and the second charging output terminal Vo2, and adjusting the two charging outputs without affecting each other.

[0044] In the dual-output flyback converter circuit in the related art, when one of the discharge branches is in an unloaded state, the flyback converter becomes a single-output. At this time, the load of the circuit is entirely borne by one discharge branch, resulting in a large load rate of the discharge branch, which will increase the stress of the switch device and the energy storage device in the discharge branch, affecting the working life of the switch device and the energy storage device, thereby resulting in a shorter working life of the flyback converter. In addition, when the flyback converter becomes a single-output, when the capacitance value of the energy storage capacitor on the discharge branch is small, it cannot meet the needs of some electronic devices that require a large charging power, affecting the output power quality.

[0045] For example, when Figure 1 In the dual-output flyback converter circuit shown, only the first charging output terminal Vo1 is connected to a load, and the second charging output terminal Vo2 is not connected to a load. At this time, the entire load of the circuit is borne by the first charging output terminal Vo1. In this way, the voltage and current on the first charging output terminal Vo1 are relatively large, and the voltage and current stresses on the first switch S11 and the third capacitor C1 on the first charging output terminal Vo1 are relatively large. Long-term operation is likely to damage the first switch S11 and the third capacitor C1, resulting in a short working life of the flyback converter. In addition, when the flyback converter is a single-channel output, due to the small capacitance value of the third capacitor C1 on the first charging output terminal Vo1, it cannot meet the needs of some electronic devices that require a large charging power. And when the capacitance value of the third capacitor C1 on the first charging output terminal Vo1 is relatively small, the voltage ripple output by the first charging output terminal Vo1 is relatively large, affecting the charging stability.

[0046] In order to overcome the defects in the above-mentioned related technologies, the present application provides a multi-output flyback conversion circuit, which includes a primary control circuit, a secondary control circuit, a transformer, a primary transistor, a load detection circuit, a voltage sampling circuit, a voltage regulation circuit and at least two discharge branches. Among them, the sampling ends of the load detection circuit and the voltage sampling circuit are both connected to the output end of the discharge branch, and the output ends of the load detection circuit and the voltage sampling circuit are both connected to the voltage regulation circuit; the load detection circuit is used to detect whether there is a load connected to the output end of the discharge branch, and output the load detection result to the voltage regulation circuit; the voltage sampling circuit is used to sample the voltage value of the output end of each discharge branch, and output the voltage sampling result to the voltage regulation circuit; the voltage regulation circuit is used to determine, based on the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a first regulation signal to the secondary control circuit; the secondary control circuit is used to first adjust the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch according to the first regulation signal, and then control the switch circuit to be turned on, so that all the discharge branches are in a conducting state. According to the multi-channel output flyback conversion circuit provided by the present application, when the multi-channel output flyback conversion circuit is connected to only one electronic device, that is, when the multi-channel output flyback conversion circuit is a single-channel output, the voltage of the remaining unloaded discharge branches is adjusted to be the same as that of the branch connected to the load, thereby reducing the voltage impact on the discharge branch; in addition, when all discharge branches are in a normally on state, the capacitors on multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress of the switch devices and capacitors on the discharge branch, avoiding damage to the switch devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0047] The multi-output flyback conversion circuit provided in the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods of the specification.

[0048] It can be understood that the multi-channel output flyback conversion circuit provided by the present application can specifically include two or more discharge branches, so that multiple charging ports with different interfaces can be set to meet the charging needs of electronic devices with different interface types. In order for technical personnel to better understand the multi-channel output flyback conversion circuit provided by the present application, the multi-channel output flyback conversion circuit of the present application is explained below using a dual-channel output flyback conversion circuit as an example.

[0049] Figure 2 One of the schematic diagrams of the dual-output flyback conversion circuit structure provided in the embodiment of the present application is shown in FIG. Figure 2As shown, the dual-output flyback conversion circuit includes: a primary control circuit 21, a secondary control circuit 23, a transformer T2, a primary transistor Q10, a load detection circuit 24, a voltage sampling circuit 25, a voltage regulation circuit 26 and two discharge branches; specifically, the two discharge branches in this embodiment are a first discharge branch Vo3 and a second discharge branch Vo4.

[0050] Among them, the first end of the primary winding Np of the transformer T2 is used to receive the power supply voltage Vin, the second end of the primary winding Np is connected to the first electrode of the primary transistor Q10, the second electrode of the first transistor Q10 is grounded GND, and the control electrode of the first transistor Q10 is connected to the primary control circuit 21. The primary control circuit 21 is used to control the conduction and shutdown of the first transistor Q10, thereby controlling the output energy of the transformer T2.

[0051] Among them, the first end of the secondary winding Ns of the transformer T2 is respectively connected to the input end of the first discharge branch Vo3 and the input end of the second discharge branch Vo4, the second end of the secondary winding Ns is connected to the negative electrode of the first diode D20, the positive electrode of the first diode D20 is grounded GND, the output end of the first discharge branch Vo3 is used to output the first discharge voltage, and the output end of the second discharge branch Vo4 is used to output the second discharge voltage. In actual application scenarios, the output ends of multiple discharge branches can be set with the same or different types of charging interfaces. For example, the output end of the first discharge branch Vo3 can be set with a USB-A interface, and the output end of the second discharge branch Vo4 can be set with a USB-C interface, so that the two interfaces can charge electronic devices of two interface types at the same time. Alternatively, the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 are both set with USB-C interfaces, so that two electronic devices with USB-C interfaces can also be charged at the same time. Specifically, the number of discharge branch settings and the setting of the interface type of each discharge branch output can be adjusted according to the actual application scenario, which will not be repeated here.

[0052] It should be noted that, in the present embodiment, the first end of the primary winding Np of the transformer T2 is an opposite-name end, and the second end thereof is a like-name end, and the first end of the secondary winding Ns is a like-name end, and the second end thereof is an opposite-name end; in other embodiments, the first end of the primary winding Np of the transformer T2 may be a like-name end, and the second end thereof may be an opposite-name end, and the first end of the secondary winding Ns may be an opposite-name end, and the second end thereof may be a like-name end.

[0053] Each discharge branch includes a switch circuit and a first capacitor, the switch circuit is arranged between the input end and the output end of the discharge branch, the first end of the first capacitor is connected to the discharge branch, the second end of the first capacitor is grounded, and the first capacitor is used to store energy during the discharge process of the discharge branch to the external electronic device. The secondary control circuit 23 is respectively connected to the switch circuits on the two discharge branches, and the secondary control circuit 23 is used to control the conduction and shutdown of each switch circuit, thereby controlling the conduction or shutdown of the corresponding discharge branch.

[0054] For details, please refer to Figure 2 As shown, in this embodiment, the first discharge branch Vo3 is provided with a first switch circuit 27, which is connected in series between the input end and the output end of the first discharge branch Vo3, so as to control the on and off of the first discharge branch Vo3; the second discharge branch Vo4 is provided with a second switch circuit 28, which is connected in series between the input end and the output end of the second discharge branch Vo4, so as to control the on and off of the second discharge branch Vo4. Among them, the control ends of the first switch circuit 27 and the second switch circuit 28 are both connected to the secondary control circuit 23, so that the secondary control circuit 23 can output corresponding control signals to control the on and off of the first switch circuit 27 and the second switch circuit 28, so as to control the on or off of the first discharge branch Vo3 and the second discharge branch Vo4.

[0055] For details, please refer to Figure 2 As shown, in this embodiment, the first discharge branch Vo3 includes a first capacitor C11, a first end of a first switch circuit 27 is connected to the same-name end of the secondary winding Ns of the transformer T2, a second end of the first switch circuit 27 is connected to the first end of the first capacitor C11, and the first capacitor C11 is grounded GND. Correspondingly, the second discharge branch Vo4 includes a second capacitor C12, a first end of a second switch circuit 28 is connected to the same-name end of the secondary winding Ns of the transformer T2, a second end of the second switch circuit 28 is connected to the first end of the second capacitor C12, and the second capacitor C12 is grounded GND.

[0056] The sampling ends of the load detection circuit 24 and the voltage sampling circuit 25 are connected to the output ends of all the discharge branches, and the output ends of the load detection circuit 24 and the voltage sampling circuit 25 are connected to the voltage regulation circuit 26. The load detection circuit 24 is used to detect whether there is a load connected to the output end of each discharge branch, and output the load detection result to the voltage regulation circuit 26; the voltage sampling circuit 25 is used to sample the voltage value of the output end of each discharge branch, and output the voltage sampling result to the voltage regulation circuit 26; the voltage regulation circuit 26 is used to determine whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch is connected to the load among all the discharge branches according to the load detection result and the voltage sampling result, and if so, output a first regulation signal to the secondary control circuit 23; the secondary control circuit 23 is used to first adjust the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch according to the first regulation signal, and then control the switch circuit to turn on, so that all the discharge branches are in the on state.

[0057] For details, please refer to Figure 2 As shown, in this embodiment, the output end of the first discharge branch Vo3 is connected to the sampling ends of the load detection circuit 24 and the voltage sampling circuit 25 respectively. The load detection circuit 24 can determine whether an electronic device is connected to the output end of the first discharge branch Vo3 by sampling the impedance change of the output end of the first discharge branch Vo3. When an electronic device is connected to the output end of the first discharge branch Vo3, the impedance of the output end of the first discharge branch Vo3 will become smaller. Conversely, when the output end of the first discharge branch Vo3 is not connected to an electronic device, that is, when the output end of the first discharge branch Vo3 is not connected to a load, the impedance of the output end of the first discharge branch Vo3 is relatively large.

[0058] The voltage sampling circuit 25 is used to sample the output voltage value of the first discharge branch Vo3, and send the sampled output voltage value of the first discharge branch Vo3 to the voltage regulating circuit 26. Correspondingly, the output end of the second discharge branch Vo4 of this embodiment is also connected to the sampling end of the load detection circuit 24 and the voltage sampling circuit 25 respectively. The load detection circuit 24 can determine whether an electronic device is connected to the output end of the second discharge branch Vo4 by sampling the impedance change of the output end of the second discharge branch Vo4. When an electronic device is connected to the output end of the second discharge branch Vo4, that is, when a load is connected to the output end of the second discharge branch Vo4, the impedance of the output end of the second discharge branch Vo4 will become smaller. On the contrary, when the output end of the second discharge branch Vo4 is not connected to an electronic device, the impedance of the output end of the second discharge branch Vo4 is larger. The voltage sampling circuit 25 is used to sample the output voltage value of the second discharge branch Vo4, and send the sampled output voltage value of the second discharge branch Vo4 to the voltage regulating circuit 26.

[0059] The voltage regulating circuit 26 of this embodiment can determine whether a load is connected to each discharge branch according to the received load detection result and voltage sampling result, and can also determine the voltage value of the output end of each discharge branch.

[0060] Specifically, in this embodiment, the voltage regulation circuit 26 determines whether there are loads connected to the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 at the same time based on the received load detection results and voltage sampling results. If only one discharge branch has a load connected, for example, the voltage regulation circuit 26 determines that only the first discharge branch Vo3 has a load connected, or both the first discharge branch Vo3 and the second discharge branch Vo4 are connected to loads at the initial moment, but at a certain moment the load on the second discharge branch Vo4 is disconnected, then only the first discharge branch Vo3 is currently connected to the load, and at this time the first discharge branch Vo3 is considered to be the target discharge branch. When the voltage regulating circuit 26 determines that only the first discharge branch Vo3 is connected to a load, it first determines whether the voltage value of the second discharge branch Vo4 is lower than the voltage value of the target discharge branch. If so, it outputs the first regulating signal PAR1 to the secondary control circuit 23. After receiving the first regulating signal PAR1, the secondary control circuit 23 first regulates the voltage value on the second discharge branch Vo4 to the same value as that of the first discharge branch Vo3, and then controls the first discharge branch Vo3 and the second discharge branch Vo4 to be in a normally on state.

[0061] In this embodiment, when only the first discharge branch Vo3 in the two-way output flyback conversion circuit has a load connected, the secondary control circuit 23 controls the second discharge branch Vo4 to also be turned on. At this time, the second capacitor C12 on the second discharge branch Vo4 is equivalent to being connected in parallel with the first capacitor C11 on the first discharge branch Vo3, and jointly bears the energy of the load at the output end of the first discharge branch Vo3. At the same time, the stress of the first switch circuit 27 on the first discharge branch Vo3 is also reduced. In this way, the first switch circuit 27 and the first capacitor C11 can be avoided from being damaged due to excessive stress, thereby ensuring the working life of the dual-way output flyback conversion circuit.

[0062] Moreover, before the secondary control circuit 23 controls the first discharge branch Vo3 and the second discharge branch Vo4 to be in a normally on state, the secondary control circuit 23 first raises the voltage value at the output end of the second discharge branch Vo4 to the same value as that of the first discharge branch Vo3, so that the voltage values ​​at the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 are the same, which can reduce voltage shock and further ensure the working life of the circuit.

[0063] Among them, when the voltage value at the output end of the second discharge branch Vo4 is lower than the voltage value at the output end of the first discharge branch Vo3, the secondary control circuit 23 can control the second switch circuit 28 on the second discharge branch Vo4 to turn on, charge the second capacitor C12 on the second discharge branch Vo4, so as to increase the voltage value on the second discharge branch Vo4 to the same as the voltage value on the first discharge branch Vo3.

[0064] It can be understood that, for the dual-output flyback conversion circuit of this embodiment, since the first discharge branch Vo3 and the second discharge branch Vo4 are two output branches arranged in parallel, the above effect can also be achieved when only a load is connected to the second discharge branch Vo4, which will not be repeated here.

[0065] It can be understood that, based on the dual-output flyback conversion circuit provided in the above embodiment, since each discharge branch is a parallel structure, and the structure of each discharge branch and the connection relationship with the secondary winding Ns are the same, therefore, in actual application scenarios, the output branches in the multi-output flyback conversion circuit can be increased to three or four discharge branches as needed.

[0066] In one embodiment, the flyback conversion circuit includes multiple output branches, the sampling ends of the load detection circuit 24 and the voltage sampling circuit 25 are connected to the output end of each discharge branch, and the output ends of the load detection circuit 24 and the voltage sampling circuit 25 are connected to the voltage regulation circuit 26; the load detection circuit 24 is used to detect whether there is a load connected to the output end of each discharge branch, and output the load detection result to the voltage regulation circuit 26; the voltage sampling circuit 25 is used to sample the voltage value of the output end of each discharge branch, and output the voltage sampling result to the voltage regulation circuit 26; the voltage regulation circuit 26 is used to determine, based on the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a first regulation signal to the secondary control circuit 23; the secondary control circuit 23 is used to first increase the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch according to the first regulation signal, and then control all switch circuits to be turned on, so that all discharge branches are in a normally on state.

[0067] According to the multi-channel output flyback conversion circuit provided in this embodiment, when the multi-channel output flyback conversion circuit is connected to only one electronic device, that is, when the multi-channel output flyback conversion circuit is a single-channel output, the voltage of the remaining unloaded discharge branches is adjusted to be the same as that of the branch connected to the load, thereby reducing the voltage impact on the discharge branch; in addition, when all discharge branches are in a normally on state, the capacitors on the multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress of the switch devices and capacitors on the discharge branch, avoiding damage to the switch devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0068] In one embodiment, each discharge branch further includes a voltage pull-down branch, the input end of the voltage pull-down branch is connected to the output end of the discharge branch, and the output end of the voltage pull-down branch is grounded GND; a voltage pull-down circuit is used to receive a control signal to pull down the voltage value on the discharge branch to a preset value. It can be understood that the voltage pull-down circuit is mainly used to pull down the voltage on the positive electrode of the discharge branch, so it can also be understood as a current discharge path. A switch and a resistor can be commonly used in series to form a current discharge path, so as to achieve the purpose of pulling down the voltage on the positive electrode of the discharge branch.

[0069] Figure 3 For the second schematic diagram of the dual-output flyback conversion circuit structure provided in the embodiment of the present application, please refer to Figure 3 As shown, in this embodiment, a first voltage pull-down circuit 29 is provided on the first discharge branch Vo3, and the first voltage pull-down circuit 29 includes a first switch S1 and a first resistor R1. The first end of the first switch S1 is connected to the first end of the first capacitor C11, the second end of the first switch S1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is grounded GND. When the first switch S1 is closed, it can form a current discharge path with the first resistor R1 to lower the voltage on the first end of the first capacitor C11, thereby achieving the purpose of lowering the voltage on the first discharge branch Vo3. Correspondingly, a second voltage pull-down circuit 30 is provided on the second discharge branch Vo4, and the second voltage pull-down circuit 30 includes a second switch S2 and a second resistor R2. The first end of the second switch S2 is connected to the first end of the second capacitor C12, the second end of the second switch S2 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded GND. When the second switch S2 is closed, it can form a current discharge path with the second resistor R2 to lower the voltage on the first end of the second capacitor C12, thereby achieving the purpose of lowering the voltage on the second discharge branch Vo4.

[0070] In one application scenario, the voltage regulation circuit 26 is also used to determine, based on the load detection results and the voltage sampling results, whether the voltage values ​​of the remaining discharge branches are higher than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load. If so, a second regulation signal is output to the corresponding voltage lowering branch; the voltage lowering branch is used to lower the voltage value on the corresponding discharge branch to the same value as the target discharge branch according to the second regulation signal.

[0071] Specifically, in this embodiment, the control ends of the first switch S1 and the second switch S2 are connected to the voltage regulation circuit 26. The voltage regulation circuit 26 can output a control signal to control the first switch S1 or the second switch S2 to be turned on, so that the corresponding voltage pull-down circuit forms a current discharge path to lower the voltage value on the corresponding discharge branch.

[0072] It can be understood that the first switch S1 and the second switch S2 in this embodiment can be switch tubes commonly used in the sampling circuit field. The two ends of the switch tube are connected in series in the circuit, and the control end of the switch tube is connected to the voltage regulation circuit 26 to receive the on-off control signal output by the voltage regulation circuit 26, thereby controlling the conduction and shutdown of the switch tube.

[0073] In this way, when the circuit changes from a multi-channel load to a single-channel load, the voltage-lowering branch is first controlled to lower the voltage of the branch with a higher output voltage to the same value as the discharge branch currently connected to the load, so that the voltage of the remaining unloaded discharge branches is adjusted to the same value as the branch connected to the load, thereby reducing the voltage impact on the discharge branch and allowing the capacitors on multiple discharge branches to be connected in parallel to jointly bear the load energy, thereby reducing the stress on the switching devices and capacitors on the discharge branch, avoiding damage to the switching devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0074] In this embodiment, when only the first discharge branch Vo3 in the two-way output flyback conversion circuit has a load connected, when the voltage regulating circuit 26 determines that the voltage on the second discharge branch Vo4 is higher than the voltage on the first discharge branch Vo3, the voltage lowering branch is controlled to lower the voltage of the branch with a higher output voltage to the same value as the discharge branch currently connected to the load, and then the secondary control circuit 23 controls the second discharge branch Vo4 to also be turned on. At this time, the second capacitor C12 on the second discharge branch Vo4 is equivalent to being connected in parallel with the first capacitor C11 on the first discharge branch Vo3, and jointly bears the energy of the load at the output end of the first discharge branch Vo3, and at the same time, the stress of the first switch circuit 27 on the first discharge branch Vo3 is also reduced, so that the first switch circuit 27 and the first capacitor C11 can be avoided from being damaged due to excessive stress, thereby ensuring the working life of the dual-way output flyback conversion circuit.

[0075] In one embodiment, when only one target discharge branch among all the discharge branches in the multi-output flyback conversion circuit is connected to the load, there are voltage values ​​higher than the voltage value of the target discharge branch and voltage values ​​lower than the voltage value of the target discharge branch in the remaining discharge branches; the secondary control circuit 23 is also used to first increase the voltage value of the corresponding discharge branch to the same value as the voltage value of the target discharge branch according to the first adjustment signal PAR1; the voltage lowering branch is also used to first lower the voltage value on the corresponding discharge branch to the same value as the target discharge branch according to the second adjustment signal, and then the secondary control circuit 23 is also used to control all the discharge branches to be turned on. In this way, firstly, the voltage of the remaining unloaded discharge branches is adjusted to the same voltage value as the branch connected to the load, so as to reduce the voltage impact on the discharge branch; in addition, when all the discharge branches are in the normally on state, the capacitors on multiple discharge branches are connected in parallel to jointly bear the load energy, thereby improving the maximum power output of a single port, reducing the low output voltage ripple, and the stress of the switch devices and capacitors on the discharge branch, avoiding damage to the switch devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0076] Exemplarily, in a three-way output flyback conversion circuit, the three outputs are the first discharge branch Vo3, the second discharge branch Vo4 and the third discharge branch, and only the first discharge branch Vo3 is connected to a load, the voltage on the second discharge branch Vo4 is higher than the voltage on the first discharge branch Vo3, and the voltage value on the third discharge branch is lower than the voltage value on the first discharge branch Vo3, then after the voltage regulation circuit 26 obtains the load detection result and the voltage sampling result, it outputs a second regulation signal to the voltage lowering branch, and the voltage lowering branch is turned on after receiving the second regulation signal to lower the voltage value on the second discharge branch Vo4 to the same value as the first discharge branch Vo3; at the same time, the voltage regulation circuit 26 The voltage regulation circuit 26 also outputs a first regulation signal PAR1 to the secondary control circuit 23. After receiving the first regulation signal PAR1, the secondary control circuit 23 raises the voltage value on the third discharge branch to the same value as that of the first discharge branch Vo3, so that the output voltages on the three discharge branches are the same, thereby reducing the voltage impact on the discharge branches; finally, the secondary control circuit 23 also controls the three discharge branches to be in the on state, so that the capacitors on the three discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress of the switch devices and capacitors on the discharge branches, avoiding damage to the switch devices and capacitors due to excessive stress, and ensuring the working life of the multi-channel output flyback conversion circuit.

[0077] In one embodiment, each discharge branch of this embodiment further includes a load switch; the first end of the load switch is connected to the first end of the first capacitor, the second end of the load switch is the output end of the discharge branch, and the control end of the load switch is connected to the voltage regulating circuit 26; the voltage regulating circuit 26 is also used to control the load switch to turn on when it is detected that a load is connected to the output end of the discharge branch, and to control the load switch to turn off when it is detected that the output end of the discharge branch is not connected to the load. It can be understood that the load switch is set on the line close to the output end of each discharge branch, and the conduction or shutdown of the load switch will not affect whether the first capacitor on the switch branch is connected. When it is detected that the output end of the discharge branch is not connected to the load, the load switch is controlled to turn off to avoid the output end being charged, thereby improving the safety of the circuit.

[0078] In one embodiment, each discharge branch also includes a third capacitor, a first end of the third capacitor is connected to the second end of the load switch, and a second end of the third capacitor is grounded. The third capacitor is used to filter the voltage signal output by the discharge branch to filter out high-frequency signals in the voltage signal.

[0079] For details, please refer to Figure 2 As shown, the first discharge branch Vo3 includes a first load switch Q3 and a third capacitor C13. The first load switch Q3 can adopt an NMOS (N-Metal-Oxide-Semiconductor) tube. In other embodiments, the first load switch Q3 can also adopt a PMOS (P-Metal-Oxide-Semiconductor) tube. For example, when the first load switch Q3 adopts an NMOS tube, its first pole is a drain, its second pole is a source, and its control pole is a gate. The drain of the first load switch Q3 is connected to the first end of the first capacitor C11, the source of the first load switch Q3 is a voltage output terminal, and the source of the first load switch Q3 is connected to the first end of the third capacitor C13, and the second end of the third capacitor C13 is grounded GND. The third capacitor C13 plays a filtering role in the first discharge branch Vo3, which is mainly used to filter out high-frequency signals in the voltage signal.

[0080] Among them, the second discharge branch Vo4 includes a second load switch Q4 and a fourth capacitor C14, and the second load switch Q4 can adopt an NMOS (N-Metal-Oxide-Semiconductor) tube. In other embodiments, the second load switch Q4 can also adopt a PMOS (P-Metal-Oxide-Semiconductor) tube. For example, when the second load switch Q4 adopts an NMOS tube, its first pole is a drain, its second pole is a source, and its control pole is a gate. The drain of the second load switch Q4 is connected to the first end of the fourth capacitor C14, the source of the second load switch Q4 is a voltage output terminal, and the source of the second load switch Q4 is connected to the first end of the fourth capacitor C14, and the second end of the fourth capacitor C14 is grounded GND. The fourth capacitor C14 plays a filtering role in the second discharge branch Vo4, which is mainly used to filter out high-frequency signals in the voltage signal.

[0081] Among them, the load detection circuit 24 in this embodiment is mainly used to determine whether there is a load connected to the output end of the discharge branch by detecting the size of the impedance of the output end of each discharge branch. Since the load detection circuit 24 is a commonly used and mature functional circuit in the circuit field, it is easy to implement for technicians in the circuit field and will not be repeated here.

[0082] Among them, the voltage sampling circuit 25 of this embodiment can adopt the voltage sampling circuit structure commonly used in the field of sampling circuits. For example, in some embodiments, a voltage sampling circuit composed of a sampling resistor and an amplifier can be used to convert the voltage signal into a current signal through the sampling resistor, and then amplify it through the amplifier to meet the input voltage range requirements of the single-chip microcomputer. The specific circuit design includes using a resistor divider and an operational amplifier to calculate the voltage amplification gain. In other embodiments, a Hall sensor circuit can also be used to implement voltage sampling. The Hall sensor can directly measure the high voltage signal and convert it into a voltage signal.

[0083] Among them, the voltage regulation circuit of this embodiment is essentially a logic processing circuit, that is, based on the received load detection results and voltage sampling results, it can be determined whether there is a load connected to each discharge branch, and at the same time, the voltage value at the output end of each discharge branch can be determined, and then it can be determined whether the two meet the preset judgment logic, and the corresponding trigger signal is output according to the determination result to trigger the secondary control circuit 23 or the voltage pull-down branch to work.

[0084] It should be noted that, in a flyback conversion circuit with multiple outputs, in order to enable the load detection circuit 24 to detect whether the output end of each discharge branch is connected to the load, the load detection circuit 24 has multiple groups of sampling ends, each group of sampling ends is respectively connected to the output end of one discharge branch, or the load detection circuit 24 includes multiple load detection sub-circuits, each load detection sub-circuit can detect whether one discharge branch is connected to the load, so that the load detection circuit 24 can detect whether the output end of each discharge branch is connected to the load.

[0085] It should be noted that, in a flyback conversion circuit with multiple outputs, in order to enable the voltage sampling circuit 25 to sample the voltage value at the output end of each discharge branch, the voltage sampling circuit 25 has multiple groups of sampling ends, each group of sampling ends is respectively connected to the output end of one discharge branch, or the voltage sampling circuit 25 includes multiple voltage sampling sub-circuits, each voltage sampling sub-circuit can sample the voltage at the output end of one discharge branch, so that the voltage sampling circuit 25 can sample the voltage at the output end of each discharge branch.

[0086] In one embodiment, the switch circuit includes a group of two transistors arranged back to back, and the transistors arranged back to back can prevent the output energy from being mutually injected. In the PD (Power Delivery) application scenario, since the voltage output by the first discharge branch Vo3 and the second discharge branch Vo4 needs to be adjustable, the relative magnitude of the voltage output on the first discharge branch Vo3 and the second discharge branch Vo4 will change, so the first switch circuit 27 and the second switch circuit 28 need to be able to withstand bidirectional withstand voltage. Therefore, when the first switch circuit 27 and the second switch circuit 28 of this embodiment are implemented using MOS tubes, due to the body diode, the first switch circuit 28 and the second switch circuit 28 both require two back-to-back MOS tubes, and the MOS tube can specifically use other types of power devices such as MOSFET tubes, GaN tubes, and SiC tubes.

[0087] For details, please refer to Figure 2 and Figure 3As shown, in this embodiment, the first switch circuit 27 includes a first transistor Q11 and a second transistor Q12; the first electrode of the first transistor Q11 is connected to the first end of the secondary winding of the transformer T2, the second electrode of the first transistor Q11 is connected to the second electrode of the second transistor Q12, and the first electrode of the second transistor Q12 is connected to the first end of the first capacitor C11; the control electrodes of the first transistor Q11 and the second transistor Q12 are both connected to the secondary control circuit 23; the secondary control circuit 23 is used to control the conduction and shutdown of the first transistor Q11 and the second transistor Q12. Among them, the second switch circuit 28 includes a third transistor Q21 and a fourth transistor Q22; the first electrode of the third transistor Q21 is connected to the first end of the secondary winding of the transformer T2, the second electrode of the third transistor Q21 is connected to the second electrode of the fourth transistor Q22, and the first electrode of the fourth transistor Q22 is connected to the first end of the second capacitor C12; the control electrodes of the third transistor Q21 and the fourth transistor Q22 are both connected to the secondary control circuit 23; the secondary control circuit 23 is used to control the conduction and shutdown of the third transistor Q21 and the fourth transistor Q22. Specifically, the secondary control circuit 23 includes four drive terminals, namely a first drive terminal D11, a second drive terminal D12, a third drive terminal D21 and a fourth drive terminal D22. The first drive terminal D11 is connected to the control electrode of the first transistor Q11, the second drive terminal D12 is connected to the control electrode of the second transistor Q12, the third drive terminal D21 is connected to the control electrode of the third transistor Q21, and the fourth drive terminal D22 is connected to the control electrode of the fourth transistor Q22.

[0088] Among them, the first transistor Q11, the second transistor Q12, the third transistor Q21 and the fourth transistor Q22 of this embodiment can adopt NMOS (N-Metal-Oxide-Semiconductor) tubes, specifically MOSFET tubes, GaN tubes, and SiC tubes; in other embodiments, the first transistor Q11, the second transistor Q12, the third transistor Q21 and the fourth transistor Q22 can also adopt PMOS (P-Metal-Oxide-Semiconductor) tubes. For example, when the first transistor Q11, the second transistor Q12, the third transistor Q21 and the fourth transistor Q22 of this embodiment adopt NMOS tubes, their first pole is the drain, their second pole is the source, and their control pole is the gate.

[0089] In other embodiments, the two back-to-back transistors in the first switch circuit 27 and the second switch circuit 28 may be replaced by a bidirectional switch, which can also prevent the output energy from being injected into each other.

[0090] In one embodiment, the voltage regulation circuit 26 is further used to output a third regulation signal to the secondary control circuit 23 when it is determined, based on the load detection result and the voltage sampling result, that a load is connected to the output end of at least two of the multiple discharge branches; the secondary control circuit 23 is further used to control the conduction time ratio of the switch circuit on the discharge branch with the load connected according to the third regulation signal to adjust the discharge power at the output end of each discharge branch.

[0091] For details, please refer to Figure 2 and Figure 3 As shown, the voltage regulating circuit 26 determines that the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 are both connected to the load according to the load detection result and the voltage sampling result, and then outputs a third regulating signal to the secondary control circuit 23; the secondary control circuit 23 is used to control the conduction time ratio of the switch circuits on the first discharge branch Vo3 and the second discharge branch Vo4 according to the third regulating signal and the energy ratio required by the load on the output ends of the first discharge branch Vo3 and the second discharge branch Vo4, so as to adjust the discharge power of the output ends of each discharge branch. Specifically, the conduction time of the corresponding switch circuit is longer when the energy required by the load on the discharge branch is larger, so that dual-channel output can be realized to charge the electronic device at the same time.

[0092] In one application scenario, after the secondary control circuit 23 controls all the discharge branches to be in the on state, the primary control circuit 21 is also used to control the on-time ratio of the primary transistor Q10 to control the discharge power output by the discharge branch. That is, after the load on the secondary output end of the circuit is stably connected, the total discharge power output by the discharge branch can be controlled by controlling the on-time ratio of the primary transistor Q10.

[0093] Figure 4 The third schematic diagram of the dual-output flyback conversion circuit structure provided in the embodiment of the present application is shown in FIG. Figure 4 As shown, in some embodiments, the load detection circuit 24, the voltage sampling circuit 25, and the voltage regulation circuit 26 in the above embodiments can be integrated into a protocol chip 40 to facilitate the actual layout of the circuit. For example, the protocol chip 40 includes a plurality of sampling pins and signal output pins, each sampling pin is respectively connected to the output end of each discharge branch to sample whether the output end of each discharge branch is connected to the load and to sample the voltage value of the output end of each discharge branch, and the signal output pin is used to output the above regulation signal and switch control signal.

[0094] Figure 5 For a schematic diagram of the protocol chip structure provided in the embodiment of this application, please refer to Figure 5As shown, the protocol chip 40 includes the above-mentioned load detection circuit 24, voltage sampling circuit 25 and voltage regulation circuit 26. The input end of the protocol chip 40 is respectively connected to the output end of the first discharge branch Vo3 and the second discharge branch Vo4. The protocol chip 40 at least includes signal output pins, wherein the first signal output pin L1 is connected to the secondary control circuit 23 to output the first voltage regulation signal and the third voltage regulation signal to the secondary control circuit 23; the second signal output pin L2 and the third signal output pin L3 are respectively connected to the control electrodes of the switches of the two voltage pull-down circuits. The fourth signal output pin L4 and the fifth signal output pin L5 are respectively connected to the control electrodes of the load switches on the two discharge branches.

[0095] Please continue to see Figure 2 As shown, in one embodiment, the multi-channel output flyback conversion circuit also includes a rectifier D1, and a voltage-stabilizing capacitor Cin is connected in parallel to the output end of the rectifier D1. The rectifier D1 can rectify the AC power into direct current, and then the voltage is adjusted by the transformer T2 to charge the electronic device.

[0096] In one embodiment, see Figure 2 and Figure 3 As shown, the dual-output flyback conversion circuit further includes an isolation communication circuit 22, and the primary control circuit 21 is electrically connected to the secondary control circuit 23 via the isolation communication circuit 22. It can be understood that during the operation of the circuit, the isolation communication circuit 23 mainly plays the role of safety, stability and noise isolation to ensure stable operation of the circuit, which will not be repeated here.

[0097] Figure 6 For a schematic diagram of the working process of the dual-output flyback conversion circuit provided in the embodiment of the present application, please refer to Figure 6 As shown, the working process of the dual-channel output flyback conversion circuit mainly includes: the circuit is powered on, and then the voltage regulating circuit 26 determines whether the circuit is currently a single-channel output or a dual-channel output. If it is determined that the circuit is currently a single-channel output, a parallel signal is output to the secondary control circuit 23. The parallel signal is used to instruct the secondary control circuit 23 to control the discharge branch that is not connected to the load to be temporarily turned on. The voltage regulating circuit 26 further determines whether the voltage values ​​at the output ends of the two discharge branches are the same. If they are different, the corresponding adjustment signal is output to pull up or lower the voltage value on the corresponding discharge branch; if they are the same, the secondary control circuit 23 controls the two discharge branches to be in a normally on state to achieve the purpose of current sharing of capacitors in parallel. If it is determined that the circuit is currently a dual-channel output, there is no need to output a parallel signal to the secondary control circuit 23, and then the two discharge branches are controlled to be complementary to each other to charge the load, and at the same time, the conduction time ratio of the two discharge branches is controlled according to the energy ratio required by the load on the two discharge branches. Among them, Figure 6FB is the control signal output to the primary transistor Q10, COMP1 and COMP2 can represent the power required by the first load and the second load respectively. In dual-channel output, FB=k(COMP1+COMP2), k is a constant less than 1; when the circuit is a single-port output, FB=COMP1 or FB=COMP2. In order to meet the single-port output power, there is no need to add the ratio k.

[0098] An embodiment of the present application further provides a chip, which includes the multi-output flyback conversion circuit as described above.

[0099] The embodiment of the present application also provides an electronic device, which includes the multi-channel output flyback conversion circuit as described above; or includes the chip as described above. It is understandable that the electronic device can be a power adapter with multi-channel output terminals, or the electronic device can also be a portable power bank with multi-channel output terminals.

[0100] It should be noted that the above embodiments are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A multi-output flyback conversion circuit, characterized in that: include: A primary control circuit, a secondary control circuit, a transformer, a primary transistor, a load detection circuit, a voltage sampling circuit, a voltage regulating circuit and at least two discharge branches; The first end of the primary winding of the transformer is used to receive the supply voltage, the second end of the primary winding is connected to the first electrode of the primary transistor, the second electrode of the first transistor is grounded, and the control electrode of the first transistor is connected to the primary control circuit; the first end of the secondary winding of the transformer is connected to the input end of the discharge branch, the second end of the secondary winding is grounded, and the output end of the discharge branch is used to output the discharge voltage; The discharge branch includes a switch circuit and a first capacitor, wherein the switch circuit is arranged between an input end and an output end of the discharge branch, a first end of the first capacitor is connected to the discharge branch, and a second end of the first capacitor is grounded; the secondary control circuit is connected to the switch circuit and is used to control the on and off of the switch circuit; The sampling ends of the load detection circuit and the voltage sampling circuit are both connected to the output end of the discharge branch, and the load detection circuit is used to detect whether there is a load connected to the output end of the discharge branch, and output the load detection result to the voltage regulation circuit; The voltage sampling circuit is used to sample the voltage value of the output end of each discharge branch and output the voltage sampling result to the voltage regulating circuit; The voltage regulating circuit is used to determine, according to the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a first regulating signal to the secondary control circuit; The secondary control circuit is used to first adjust the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch according to the first adjustment signal, and then control the switch circuit to be turned on so that all discharge branches are in the on state.

2. The multi-output flyback converter circuit according to claim 1, characterized in that: The discharge branch further comprises a voltage-lowering branch, the input end of the voltage-lowering branch is connected to the output end of the discharge branch, and the output end of the voltage-lowering branch is grounded; The voltage regulating circuit is further used to determine, based on the load detection result and the voltage sampling result, whether the voltage values ​​of the remaining discharge branches are higher than the voltage value of the target discharge branch when only one target discharge branch among all the discharge branches is connected to the load, and if so, output a second regulating signal to the corresponding voltage lowering branch; The voltage lowering branch is used to lower the voltage value on the corresponding discharge branch to the same value as that of the target discharge branch according to the second adjustment signal.

3. The multi-output flyback converter circuit according to claim 1 or 2, characterized in that: When only one target discharge branch among all the discharge branches is connected to the load, and among the remaining discharge branches, there are voltage values ​​higher than the voltage value of the target discharge branch, and there are voltage values ​​lower than the voltage value of the target discharge branch; The secondary control circuit is also used to first increase the voltage value of the corresponding discharge branch to the same value as the voltage value of the target discharge branch according to the first adjustment signal; the voltage lowering branch is also used to first lower the voltage value on the corresponding discharge branch to the same value as the target discharge branch according to the second adjustment signal, and then the secondary control circuit is also used to control all discharge branches to be turned on.

4. The multi-output flyback converter circuit according to claim 1 or 2, characterized in that: The discharge branch further includes a load switch; a first end of the load switch is connected to a first end of the first capacitor, a second end of the load switch is an output end of the discharge branch, and a control end of the load switch is connected to a voltage regulating circuit; The voltage regulating circuit is further used to control the load switch to turn on when it is detected that a load is connected to the output end of the discharge branch, and to control the load switch to turn off when it is detected that no load is connected to the output end of the discharge branch.

5. The multi-output flyback converter circuit according to claim 4, characterized in that: The discharge branch further includes a third capacitor, a first end of the third capacitor is connected to the second end of the load switch, and a second end of the third capacitor is grounded.

6. The multi-output flyback converter circuit according to claim 1 or 2, characterized in that: The switch circuit includes a first transistor and a second transistor; The first electrode of the first transistor is connected to the first end of the secondary winding, the second electrode of the first transistor is connected to the second electrode of the second transistor, and the first electrode of the second transistor is connected to the first end of the first capacitor; the control electrodes of the first transistor and the second transistor are both connected to the secondary control circuit; The secondary control circuit is used to control the on and off of the first transistor and the second transistor.

7. The multi-output flyback converter circuit according to claim 4, characterized in that: The voltage regulating circuit is further used to output a third regulating signal to the secondary control circuit when it is determined that a load is connected to the output ends of at least two discharge branches according to the load detection result and the voltage sampling result; The secondary control circuit is further used to control the conduction time ratio of the switch circuit on the discharge branch with load access according to the third adjustment signal, so as to adjust the discharge power of the output end of each discharge branch.

8. The multi-output flyback converter circuit according to claim 1 or 2, characterized in that: After the secondary control circuit controls all the discharge branches to be in the on state, the primary control circuit is further used to control the on-time ratio of the primary transistor to control the discharge power output by the discharge branch.

9. A chip, characterized in that: It comprises the multi-output flyback conversion circuit as described in any one of claims 1 to 10.

10. An electronic device, characterized in that: It comprises the multi-output flyback conversion circuit as described in any one of claims 1 to 10; or it comprises the chip as described in claim 9.

Images