Multi-output flyback conversion circuit, chip and electronic equipment

Abstract

The present application relates to the field of switching power supply technology, and in particular to a multi-channel output flyback converter circuit, chip and electronic device. The multi-channel output flyback converter circuit 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. When only one electronic device is connected to the multi-channel discharge branch, that is, when the multi-channel output flyback converter circuit is a single-channel output, the voltage of the remaining unloaded discharge branches is adjusted to 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 conducting 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 converter circuit.

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, chip, and electronic equipment. Background Art

[0002] With the advancement of electronic technology, various types of electronic devices have emerged one after another. Different types of electronic devices may have different charging interface types. To meet the charging needs of electronic devices with different interface types, power adapters can usually be equipped with two or more different charging interfaces, each of which corresponds to a discharge branch. This allows electronic devices with different charging interfaces to be charged simultaneously. Different electronic devices have different loads, so when multiple electronic devices are charged simultaneously, the charging voltages output by each discharge branch will generally differ. To meet the charging needs of multiple electronic devices simultaneously, the flyback multi-output converter has emerged, 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 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-output flyback conversion circuit, chip and electronic device to solve the technical problem of short working life of flyback converters in related technologies.

[0005] In a first aspect, the present application provides a multi-output flyback converter circuit, comprising: 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 a 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 a 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 switching circuit to be turned on and off;

[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 a load is 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 configured to determine, based on the load detection result and the voltage sampling result, whether, when only one target discharge branch among all the discharge branches is connected to a load, the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch, 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 configured to determine, based on the load detection result and the voltage sampling result, whether, when only one target discharge branch among all the discharge branches is connected to a load, the voltage values ​​of the remaining discharge branches are higher than the voltage value of the target discharge branch; 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 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;

[0015] The secondary control circuit is further 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 further 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 further used to control all discharge branches to be turned on.

[0016] In one possible design, the discharge branch further includes a load switch; a first end of the load switch is connected to the 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 configured 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 switching 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 one possible design, the voltage regulation circuit is further configured to output a third regulation signal to the secondary control circuit when determining, based on the load detection result and the voltage sampling result, that a load is connected to the output ends of at least two discharge branches;

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

[0024] In one possible design, after the secondary control circuit controls all 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 comprising the 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-output flyback converter 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 transformer's primary winding is used to receive a 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 transformer's secondary winding 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 a discharge voltage. Wherein, 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 conduction and shutdown of the switch circuit; the sampling end of the load detection circuit and the voltage sampling circuit are both connected to the output end of the discharge branch, and the output end 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 configured to sample the voltage value at the output end of each discharge branch and output the voltage sampling result to the voltage regulation circuit; the voltage regulation circuit is configured 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 configured to first regulate the voltage values ​​of the remaining discharge branches to the same value as that of 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 converter circuit provided in the present application, when only one electronic device is connected to the multi-channel discharge branch, that is, when the multi-channel output flyback converter circuit has a single 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 conductive state, the capacitors on the multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress on the switching devices and capacitors on the discharge branches, avoiding damage to the switching devices and capacitors due to excessive stress, and ensuring the service life of the multi-channel output flyback converter circuit.

[0028] The beneficial effects provided in the above-mentioned second aspect and the various possible designs of the above-mentioned second aspect can be referred to the beneficial effects brought about by the above-mentioned first aspect and the 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 related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. 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 converter circuit provided in the related art;

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

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

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

[0034] Figure 5 A schematic diagram of the structure of the protocol chip provided in an 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" refers to one or more, and "plurality" refers to 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: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the objects associated 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 or plural items. For example, at least one of a alone, b alone, or c alone can represent: a alone, b alone, c alone, a and b in combination, a and c in combination, b and c in combination, or a, b, and c in combination, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to 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. Therefore, they should not be understood as limiting the present application.

[0038] The terms "connected" and "connect" should be interpreted broadly. For example, "connected" or "connected" in a circuit structure can refer not only to a physical connection, but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as the circuit is interconnected. It can also refer to internal connectivity between two components. Signal connection can refer not only to signal connection through circuits but also to signal connection through media, such as radio waves. Those skilled in the art will understand the specific meanings of the above terms in this application on a case-by-case basis.

[0039] The transistor in this application is a three-terminal transistor, whose 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 have become an issue that people are most 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 compatible with 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, thereby controlling the switching power supply circuit to operate in different charging modes to meet the charging needs of various scenarios.

[0041] Currently, different types of electronic devices on the market may have different charging interface types. In order to meet the charging needs of electronic devices with different interface types, power adapters can usually be set with two or more different charging interfaces, each of which corresponds to a discharge branch. This can meet the simultaneous charging of electronic devices with different charging interfaces. For example, a fast charging adapter can achieve 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. The two outputs can charge two electronic devices at the same time without affecting each other. Among them, different electronic devices include different loads. Therefore, when multiple electronic devices are charged simultaneously, the charging voltage output by each discharge branch will generally be different.

[0042] Figure 1 For the structural diagram of the dual-output flyback conversion circuit provided by 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-name terminal of the primary winding, the source of the primary switch tube M1 is grounded GND, and the control electrode of the primary switch tube M1 is connected to the primary control unit, which is used to control the conduction or shutdown of the primary switch tube M1. The same-name terminal of the secondary winding of the first transformer T1 is respectively connected to the input terminal of the two charging output branches, and the output terminal of the charging output branch is used to connect to the load to charge the load.

[0043] Please continue to see Figure 1The dual-output flyback converter circuit provided by this related art includes two charging output terminals, namely 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 terminal and is connected to the first charging output terminal Vo1 and the second charging output terminal Vo2, respectively. The opposite-name end of the secondary winding is connected to the cathode of the secondary diode D10, and the anode of the secondary diode D10 is grounded to GND. Furthermore, the first charging output terminal Vo1 is grounded to GND via a third capacitor C1, and the second charging output terminal Vo2 is grounded to GND via a fourth capacitor C2. Furthermore, a first switch S11 is 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 connected in series between the same-name end of the secondary winding loop and the second charging output terminal Vo2. The control terminals 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 be turned on or off 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 achieving regulation of the two charging outputs without affecting each other.

[0044] In a related art dual-output flyback converter circuit, when one of the discharge branches is unloaded, the flyback converter becomes a single-output circuit. At this point, the circuit load is entirely borne by the discharge branch, resulting in a high load factor for the discharge branch. This increases the stress on the switching and energy storage devices in the discharge branch, affecting their lifespan and, consequently, shortening the flyback converter's lifespan. Furthermore, when the flyback converter is single-output, if the capacitance of the energy storage capacitor on the discharge branch is small, it cannot meet the needs of some electronic devices requiring high charging power, thus affecting the output power quality.

[0045] For example, when Figure 1 In the dual-output flyback converter circuit shown, when only the first charging output terminal Vo1 is connected to a load and the second charging output terminal Vo2 is not, the entire circuit load is borne by the first charging output terminal Vo1. This results in high voltage and current at the first charging output terminal Vo1, which in turn places high voltage and current stress on the first switch S11 and the third capacitor C1 at the first charging output terminal Vo1. This can easily damage the first switch S11 and the third capacitor C1 over long periods of operation, shortening the flyback converter's operating life. Furthermore, when the flyback converter has a single output, the relatively small capacitance of the third capacitor C1 at the first charging output terminal Vo1 makes it unsuitable for some electronic devices requiring high charging power. Furthermore, when the capacitance of the third capacitor C1 at the first charging output terminal Vo1 is relatively small, the voltage ripple outputted by the first charging output terminal Vo1 is relatively large, affecting 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 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 discharge branches are in the on state. According to the multi-channel output flyback converter circuit provided in the present application, when the multi-channel output flyback converter circuit is connected to only one electronic device, that is, when the multi-channel output flyback converter circuit has a single 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 conductive state, the capacitors on the multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress on the switching devices and capacitors on the discharge branches, avoiding damage to the switching devices and capacitors due to excessive stress, and ensuring the service life of the multi-channel output flyback converter 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.

[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 This is one of the schematic diagrams of the dual-output flyback conversion circuit structure provided in the embodiment of the present application, see 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, a first end of the primary winding Np of the transformer T2 is used to receive the power supply voltage Vin, a second end of the primary winding Np is connected to the first electrode of the primary transistor Q10, a second electrode of the first transistor Q10 is grounded GND, and a 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] The first end of the secondary winding Ns of the transformer T2 is connected to the input end of the first discharge branch Vo3 and the input end of the second discharge branch Vo4, respectively. The second end of the secondary winding Ns is connected to the cathode of the first diode D20, the anode of the first diode D20 being grounded GND. The output end of the first discharge branch Vo3 is configured to output a first discharge voltage, and the output end of the second discharge branch Vo4 is configured to output a second discharge voltage. In actual application scenarios, the output ends of the multiple discharge branches can be configured with the same or different types of charging interfaces. For example, the output end of the first discharge branch Vo3 can be configured with a USB-A interface, and the output end of the second discharge branch Vo4 can be configured with a USB-C interface. In this way, the two interfaces can simultaneously charge electronic devices with two interface types. Alternatively, the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 can both be configured with USB-C interfaces. This allows two electronic devices with USB-C interfaces to be charged simultaneously. Specifically, the number of discharge branches and the interface type of each discharge branch output can be adjusted according to the actual application scenario and will not be further described here.

[0052] It should be noted that, in this embodiment, the first end of the primary winding Np of the transformer T2 is an opposite-name end, and its second end is a like-name end, and the first end of the secondary winding Ns is a like-name end, and its second end is an opposite-name end; in other embodiments, the first end of the primary winding Np of the transformer T2 can be a like-name end, and its second end can be an opposite-name end, and the first end of the secondary winding Ns can be an opposite-name end, and its second end can 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 and output ends 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 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 connected to the switch circuits of the two discharge branches respectively. 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 and output terminals of the first discharge branch Vo3, thereby controlling the conduction and shutoff 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 and output terminals of the second discharge branch Vo4, thereby controlling the conduction and shutoff of the second discharge branch Vo4. The control terminals 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 conduction and shutoff of the first switch circuit 27 and the second switch circuit 28, thereby controlling the conduction or shutoff 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 connected to the same-name terminal of the secondary winding Ns of the transformer T2, a second end of the first switch circuit 27 connected to the first end of the first capacitor C11, and a ground connection GND of the first capacitor C11. Correspondingly, the second discharge branch Vo4 includes a second capacitor C12, a first end of a second switch circuit 28 connected to the same-name terminal of the secondary winding Ns of the transformer T2, a second end of the second switch circuit 28 connected to the first end of the second capacitor C12, and a ground connection GND of the second capacitor C12.

[0056] The sampling terminals of the load detection circuit 24 and the voltage sampling circuit 25 are both connected to the output terminals of all discharge branches, and the output terminals of the load detection circuit 24 and the voltage sampling circuit 25 are both connected to the voltage regulation circuit 26. The load detection circuit 24 is used to detect whether a load is connected to the output terminal 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 at the output terminal 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 discharge branches is connected to a load. If so, the voltage regulation circuit 26 outputs a first regulation signal to the secondary control circuit 23. The secondary control circuit 23 is used to first regulate the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch based on the first regulation signal, and then control the switch circuit to conduct so that all discharge branches are in a conducting 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 no electronic device is connected to the output end of the first discharge branch Vo3, that is, when no load is connected to the output end of the first discharge branch Vo3, the impedance of the output end of the first discharge branch Vo3 is larger.

[0058] The voltage sampling circuit 25 is configured to sample the output voltage of the first discharge branch Vo3 and transmit the sampled output voltage of the first discharge branch Vo3 to the voltage regulation circuit 26. Accordingly, the output of the second discharge branch Vo4 in this embodiment is also connected to the sampling terminals 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 of the second discharge branch Vo4 by sampling the impedance change at the output of the second discharge branch Vo4. When an electronic device is connected to the output of the second discharge branch Vo4, that is, when a load is connected to the output of the second discharge branch Vo4, the impedance of the output of the second discharge branch Vo4 decreases. Conversely, when no electronic device is connected to the output of the second discharge branch Vo4, the impedance of the output of the second discharge branch Vo4 increases. The voltage sampling circuit 25 is configured to sample the output voltage of the second discharge branch Vo4 and transmit the sampled output voltage of the second discharge branch Vo4 to the voltage regulation 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 loads are currently 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 result and voltage sampling result. 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 initially both the first discharge branch Vo3 and the second discharge branch Vo4 have loads connected, 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 regulation 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 a first regulation signal PAR1 to the secondary control circuit 23. After receiving the first regulation signal PAR1, the secondary control circuit 23 first regulates the voltage value of 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 dual-output flyback converter 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 they jointly bear 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, damage to the first switch circuit 27 and the first capacitor C11 due to excessive stress can be avoided, thereby ensuring the service life of the dual-output flyback converter circuit.

[0062] Moreover, before the secondary control circuit 23 controls the first discharge branch Vo3 and the second discharge branch Vo4 to be in the normally conducting 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. This makes the voltage values ​​at the output ends of the first discharge branch Vo3 and the second discharge branch Vo4 the same, which can reduce voltage shock and further ensure the working life of the circuit.

[0063] 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, and 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-mentioned effect can also be achieved when only a load is connected to the second discharge branch Vo4, which is not further described here.

[0065] It can be understood that, based on the dual-output flyback conversion circuit provided in the above embodiment, since the discharge branches are parallel structures, and the structures of the discharge branches and the connection relationships 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 converter circuit includes multiple output branches. The sampling terminals of a load detection circuit 24 and a voltage sampling circuit 25 are both connected to the output terminal of each discharge branch, and the output terminals of the load detection circuit 24 and the voltage sampling circuit 25 are both connected to a voltage regulation circuit 26. The load detection circuit 24 is configured to detect whether a load is connected to the output terminal of each discharge branch and output the load detection result to the voltage regulation circuit 26. The voltage sampling circuit 25 is configured to sample the voltage value of the output terminal of each discharge branch and output the voltage sampling result to the voltage regulation circuit 26. The voltage regulation circuit 26 is configured 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 a load. If so, the voltage regulation circuit 26 outputs a first regulation signal to the secondary control circuit 23. The secondary control circuit 23 is configured to first raise the voltage values ​​of the remaining discharge branches to the same value as the target discharge branch based on the first regulation signal and then control all switching circuits to conduct so that all discharge branches are in a normally on state.

[0067] According to the multi-output flyback converter circuit provided in this embodiment, when the multi-output flyback converter circuit is connected to only one electronic device, that is, when the multi-output flyback converter circuit has a single 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 conductive state, the capacitors on the multiple discharge branches are connected in parallel to jointly bear the load energy, thereby reducing the stress on the switching devices and capacitors on the discharge branches, avoiding damage to the switching devices and capacitors due to excessive stress, and ensuring the service life of the multi-output flyback converter circuit.

[0068] In one embodiment, each discharge branch further includes a voltage-lowering branch, the input of which is connected to the output of the discharge branch, and the output of which is grounded to GND; and a voltage-pull-down circuit configured to receive a control signal to lower the voltage on the discharge branch to a preset value. It is understood that the voltage-pull-down circuit is primarily configured to lower the voltage on the positive electrode of the discharge branch, and thus can also be understood as a current discharge path. Typically, a switch and a resistor are connected in series to form a current discharge path, thereby lowering 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. 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, and the second end of the first switch S1 is connected to the first end of the first resistor R1. The second end of the first resistor R1 is grounded GND. When the first switch S1 is closed, it and the first resistor R1 can form a current discharge path 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. 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 both 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. This reduces the stress on the switching devices and capacitors on the discharge branch, avoids damage to the switching devices and capacitors due to excessive stress, and ensures the working life of the multi-channel output flyback conversion circuit.

[0074] In this embodiment, when only the first discharge branch Vo3 in the dual-output flyback conversion circuit has a load connected, when the voltage regulation 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 the higher output voltage to the same value as the discharge branch currently connected to the load. Then, the secondary control circuit 23 controls the second discharge branch Vo4 to also turn 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 they jointly bear 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. This can avoid damage to the first switch circuit 27 and the first capacitor C11 due to excessive stress, thereby ensuring the service life of the dual-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, and there are voltage values ​​in the remaining discharge branches that are higher than the voltage value of the target discharge branch and voltage values ​​that are lower than the voltage value of the target discharge branch; the secondary control circuit 23 is further 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, the voltage of the remaining unloaded discharge branches is first adjusted to the same value as the voltage of the branch connected to the load, thereby reducing the voltage impact on the discharge branch; in addition, when all the discharge branches are in the normally conductive state, the capacitors on multiple discharge branches are connected in parallel to jointly bear the load energy, thereby increasing the maximum output power of a single port, reducing the low output voltage ripple, and the stress on the switching devices and capacitors on the discharge branches, thereby avoiding damage to the switching devices and capacitors due to excessive stress, and ensuring the service life of the multi-output flyback converter circuit.

[0076] For example, 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. 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. After receiving the second regulation signal, the voltage lowering branch is turned on 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 outputs a second regulation signal to the voltage lowering branch. 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. This makes the output voltages on the three discharge branches 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 and share the load energy. This reduces the stress on the switching devices and capacitors on the discharge branches, avoids damage to the switching devices and capacitors due to excessive stress, and ensures the service life of the multi-output flyback converter circuit.

[0077] In one embodiment, each discharge branch of this embodiment further includes a load switch; a first end of the load switch is connected to the first end of the first capacitor, a second end of the load switch is the output end of the discharge branch, and a control end of the load switch is connected to the voltage regulation circuit 26; the voltage regulation circuit 26 is further configured to control the load switch to turn on when a load is detected to be connected to the output end of the discharge branch, and to control the load switch to turn off when no load is detected to be connected to the output end of the discharge branch. It is understood that the load switch is disposed on a circuit near the output end of each discharge branch, and the turning on or off of the load switch does not affect whether the first capacitor on the switch branch is connected. When the output end of the discharge branch is detected to be not connected to a load, the load switch is controlled to turn off to prevent the output end from being charged, thereby improving the safety of the circuit.

[0078] In one embodiment, each 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. 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 be an NMOS (N-Metal-Oxide-Semiconductor) tube. In other embodiments, the first load switch Q3 can also be a PMOS (P-Metal-Oxide-Semiconductor) tube. For example, when the first load switch Q3 is an NMOS tube, its first electrode is the drain, its second electrode is the source, and its control electrode is the 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 the voltage output end, and the source of the first load switch Q3 is connected to the first end of the third capacitor C13. The second end of the third capacitor C13 is grounded GND. The third capacitor C13 acts as a filter in the first discharge branch Vo3, mainly used to filter out high-frequency signals in the voltage signal.

[0080] The second discharge branch Vo4 includes a second load switch Q4 and a fourth capacitor C14. The second load switch Q4 can be an NMOS (N-Metal-Oxide-Semiconductor) tube. In other embodiments, the second load switch Q4 can also be a PMOS (P-Metal-Oxide-Semiconductor) tube. For example, when the second load switch Q4 is an NMOS tube, its first electrode is a drain, its second electrode is a source, and its control electrode 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 end, and the source of the second load switch Q4 is connected to the first end of the fourth capacitor C14. The second end of the fourth capacitor C14 is grounded GND. The fourth capacitor C14 acts as a filter in the second discharge branch Vo4, mainly for filtering 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 each 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 described in detail here.

[0082] The voltage sampling circuit 25 of this embodiment can employ a common voltage sampling circuit structure in the field of sampling circuits. For example, in some embodiments, a voltage sampling circuit consisting of a sampling resistor and an amplifier can be employed. The sampling resistor converts the voltage signal into a current signal, which is then amplified by the amplifier to meet the input voltage range requirements of the microcontroller. The specific circuit design includes the use of a resistor divider and an operational amplifier to calculate the voltage amplification gain. In other embodiments, a Hall sensor circuit can be employed to implement voltage sampling. The Hall sensor can directly measure high voltage signals and convert them into voltage signals.

[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 determine whether there is a load connected to each discharge branch, and at the same time, it can determine the voltage value at the output end of each discharge branch, and then determine whether the two meet the preset judgment logic, and output the corresponding trigger signal 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 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 switching 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 injected into each other. 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. Therefore, the first switching circuit 27 and the second switching circuit 28 need to be able to withstand bidirectional voltage. Therefore, when the first switching circuit 27 and the second switching circuit 28 of this embodiment are implemented using MOS tubes, due to the body diode, the first switching circuit 28 and the second switching circuit 28 both require two back-to-back MOS tubes, and the MOS tube can specifically be other types of power devices such as MOSFET tubes, GaN tubes, SiC tubes, etc.

[0087] For details, please refer to Figure 2 and Figure 3As shown, in this embodiment, the first switching 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 switching 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] In this embodiment, the first transistor Q11, the second transistor Q12, the third transistor Q21, and the fourth transistor Q22 can be NMOS (N-Metal-Oxide-Semiconductor) transistors, specifically MOSFET transistors, GaN transistors, or SiC transistors. In other embodiments, the first transistor Q11, the second transistor Q12, the third transistor Q21, and the fourth transistor Q22 can also be PMOS (P-Metal-Oxide-Semiconductor) transistors. For example, when the first transistor Q11, the second transistor Q12, the third transistor Q21, and the fourth transistor Q22 in this embodiment are NMOS transistors, their first electrode is the drain, their second electrode is the source, and their control electrode 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 fed into each other.

[0090] In one embodiment, the voltage regulation circuit 26 is further configured to output a third regulation signal to the secondary control circuit 23 when determining, 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 configured to control, based on the third regulation signal, the conduction time ratio of the switch circuit on the discharge branch to which the load is connected, so as 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, when the voltage regulation circuit 26 determines, based on the load detection results and voltage sampling results, that a load is connected to the output ends of both the first discharge branch Vo3 and the second discharge branch Vo4, it outputs a third regulation signal to the secondary control circuit 23. The secondary control circuit 23 is configured to control the on-time ratio of the switch circuits in the first discharge branch Vo3 and the second discharge branch Vo4 based on the third regulation signal and the energy ratio required by the loads at the output ends of the first discharge branch Vo3 and the second discharge branch Vo4, thereby adjusting the discharge power at the output ends of each discharge branch. Specifically, the switch circuit with a greater energy requirement corresponds to a longer on-time. This allows dual-output to simultaneously charge electronic devices.

[0092] In one application scenario, after the secondary control circuit 23 controls all discharge branches to be in an on state, the primary control circuit 21 is further configured to control the on-time ratio of the primary transistor Q10 to control the discharge power output by the discharge branch. Specifically, after a load is stably connected to the output terminal of the secondary of the circuit, 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, voltage sampling circuit 25, and voltage regulation circuit 26 in the above-mentioned embodiments can be integrated into a protocol chip 40 to facilitate the actual layout of the circuit. For example, the protocol chip 40 includes multiple sampling pins and signal output pins. Each sampling pin is connected to the output end of each discharge branch to sample whether the output end of each discharge branch is connected to a load and to sample the voltage value of the output end of each discharge branch. The signal output pins are used to output the above-mentioned regulation signal and switch control signal.

[0094] Figure 5 For the 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 aforementioned 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 includes at least 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-output flyback conversion circuit further 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 mains 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 converter circuit further includes an isolated communication circuit 22, through which the primary control circuit 21 is electrically connected to the secondary control circuit 23. It will be appreciated that during circuit operation, the isolated communication circuit 23 primarily provides security, stability, and noise isolation to ensure stable circuit operation, and will not be further elaborated herein.

[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-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. Further, the voltage regulating circuit 26 determines whether the voltage values ​​at the output ends of the two discharge branches are the same. If different, the corresponding regulating signal is output to pull up or lower the voltage value on the corresponding discharge branch; if 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 by 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-output mode, FB = k(COMP1 + COMP2), where k is a constant less than 1. When the circuit has a single-port output, FB = COMP1 or FB = COMP2. To meet the single-port output power requirement, the ratio k does not need to be added.

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

[0099] An embodiment of the present application further provides an electronic device comprising the multi-output flyback converter circuit described above; or comprising the chip described above. It is understood that the electronic device may be a power adapter having multiple output terminals, or may be a portable power bank having multiple output terminals, etc.

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

Claims

1. A multi-output flyback converter 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 regulation circuit, and at least two discharge branches; The first end of the primary winding of the transformer is used to receive a supply voltage, the second end of the primary winding is connected to the first electrode of the first 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 a 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 switching circuit to be turned on and off; 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; The voltage regulating circuit is configured to determine, based on the load detection result and the voltage sampling result, whether, when only one target discharge branch among all the discharge branches is connected to a load, the voltage values ​​of the remaining discharge branches are lower than the voltage value of the target discharge branch, 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 includes 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 configured to determine, based on the load detection result and the voltage sampling result, whether, when only one target discharge branch among all the discharge branches is connected to a load, the voltage values ​​of the remaining discharge branches are higher than the voltage value of the target discharge branch; 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 2, wherein: 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 further 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 further 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 further 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 the first end of the first capacitor, a second end of the load switch is the output end of the discharge branch, and a control end of the load switch is connected to the voltage regulation circuit; The voltage regulating circuit is further configured 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 configured to output a third regulating signal to the secondary control circuit when it is determined, based on the load detection result and the voltage sampling result, that a load is connected to the output ends of at least two discharge branches; The secondary control circuit is further configured to control the on-time ratio of the switch circuit on the discharge branch connected to the load according to the third adjustment signal, so as to adjust the discharge power at 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 according to any one of claims 1 to 8.

10. An electronic device, characterized in that: The invention comprises the multi-output flyback converter circuit according to any one of claims 1 to 8; or comprises the chip according to claim 9.

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