Multiple output voltage supply system and control circuit, electronic package and method

Abstract

The application provides a multi-output voltage power supply system, a control circuit thereof, an electronic package and a multi-output control method. In an embodiment, the control circuit comprises a turn-on control circuit and a turn-off control circuit for controlling an energy distribution switch in a first output circuit. In a switching cycle, when a secondary side is powered, a second output circuit is powered first, the energy distribution switch is turned on to power the first output circuit when the turn-on control circuit detects that a first condition is met, and an input end of the turn-off control circuit is coupled to a secondary side winding, the energy distribution switch is turned off when the turn-off control circuit detects that a second condition is met based on a signal on the secondary side winding. The application is used to solve the stability problem of multi-output and can be applied to different working modes and working frequencies.

Description

Technical Field

[0001] This invention relates to the field of electronics, specifically but not limited to a multi-output voltage power supply system and its control circuit, electronic package, and multi-output control method. Background Technology

[0002] In electronic power supply systems, different power supplies are often required for different loads. For example, in the home appliance industry, different components such as motors and processing units require different power supplies. A traditional approach is to provide separate power supplies for each load, but this method has low integration and high system power costs. To improve the integration of power supply systems and reduce power supply costs, there is a demand for multi-output power supply systems.

[0003] Isolated power supply systems are widely used to power household appliances due to their reliability and safety. One method of power supply is to set up two output circuits on the secondary side of the isolated power supply; however, due to feedback issues, only the output voltage of one of the circuits can be controlled. Figure 1 An isolated dual-output power supply system is illustrated. This system includes a first output circuit providing a first output voltage V1 and a second output circuit providing a second output voltage V2. Voltage V2 is fed back to the primary side via devices such as optocouplers to control the primary-side switch, thereby controlling the second output voltage V2. Voltage V1 is regulated by controlling a switching transistor Q1, etc. In one embodiment, the energy supplied to the secondary side is controlled by controlling the total charging time of the first and second output circuits, achieving the regulation function. This time can be adjusted by selecting the parameters of external components. However, this control method is prone to uneven energy distribution between the two outputs when load changes occur. In some cases, when the switching transistor Q1 is turned off, the remaining energy continues to power the second output circuit, resulting in excess energy in the second output circuit and loop oscillation. Especially when the second load is light, overcharging of the second output voltage V2 is more likely to occur. Therefore, unreasonable energy distribution can lead to problems including steady-state system oscillation, abnormal dynamic response, and undervoltage during startup, with significant drawbacks.

[0004] In view of this, there is a need to provide a new structure or control method in order to solve at least some of the above problems. Summary of the Invention

[0005] In response to at least one or more of the problems in the background art, the present invention provides a control circuit, electronic package, and multi-output control method for a multi-output voltage power supply system.

[0006] According to one aspect of the present invention, a control circuit for a voltage conversion circuit with multiple outputs is provided. The voltage conversion circuit includes a transformer with a secondary winding and a first output circuit and a second output circuit coupled to the secondary winding. The first output circuit includes an energy distribution switch. The control circuit includes: a turn-on control circuit, which, in one switching cycle, when the voltage conversion circuit supplies power to the secondary side of the transformer, first supplies power to the second output circuit; when the turn-on control circuit detects that a first condition is met, the turn-on control circuit outputs a valid turn-on control signal to turn on the energy distribution switch to supply power to the first output circuit; and a turn-off control circuit, the input of which is coupled to the secondary winding; when the turn-off control circuit detects that a second condition is met based on the secondary winding signal state at its input, the turn-off control circuit outputs a valid turn-off control signal to turn off the energy distribution switch.

[0007] Optionally, the second condition includes the primary-side switch of the voltage conversion circuit being turned on.

[0008] Optionally, the second condition includes demagnetizing the secondary winding.

[0009] Optionally, the shutdown control circuit includes an OR gate, the first input of which receives a signal reflecting the primary-side switch of the voltage conversion circuit being turned on, and the second input of which receives a signal reflecting the secondary-side winding being demagnetized.

[0010] Optionally, the shutdown control circuit includes a first comparator circuit, the first input terminal of which is coupled to the secondary winding for receiving the secondary winding terminal voltage, the second input terminal of which is coupled to a threshold signal, and the output terminal of which provides a shutdown control signal.

[0011] Optionally, the conduction detection circuit includes a second comparison circuit, which is coupled to the output terminal of the first output circuit. The first condition includes the first output voltage of the first output circuit being lower than a preset voltage.

[0012] Optionally, the voltage conversion circuit includes a flyback voltage conversion circuit.

[0013] Optionally, the control circuit further includes: a trigger circuit, the first input terminal of which is coupled to the output terminal of the turn-on control circuit, and the second input terminal of which is coupled to the output terminal of the turn-off control circuit; and a drive circuit, the input terminal of which is coupled to the output terminal of the trigger circuit, and the output terminal of which is coupled to the control terminal of the energy distribution switch.

[0014] According to another aspect of the present invention, a control circuit for a voltage conversion circuit with multiple outputs is provided. The voltage conversion circuit includes a secondary winding on the secondary side and a first output circuit and a second output circuit coupled to the secondary winding. The first output circuit includes an energy distribution switch. The control circuit is characterized in that it is coupled to the secondary winding and determines whether a preset condition is met based on a signal from the secondary winding. When the preset condition is detected, the energy distribution switch is switched from a first state to a second state. The preset condition includes demagnetizing the secondary winding or turning on the primary switch of the voltage conversion circuit.

[0015] Optionally, the first state of the energy distribution switch is the off state, and the second state of the energy distribution switch is the on state. The control circuit includes: a shutdown control circuit, including a comparator circuit, which, in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, first supplies power to the first output circuit. When the comparator circuit detects that the second output voltage of the second output circuit is lower than a preset value, the shutdown control circuit outputs a valid shutdown control signal to shut down the energy distribution switch so as to supply power to the second output circuit; and an on control circuit, the input of which is coupled to the secondary winding. When the on control circuit detects that a preset condition is met based on the secondary winding signal state at the input, the on control circuit outputs a valid on control signal to turn on the energy distribution switch.

[0016] Optionally, the control circuit has a detection terminal coupled to: the upper terminal of the secondary winding; or the near-reference ground terminal of the secondary winding, opposite to the upper terminal, wherein the near-reference ground terminal of the secondary winding is coupled to the secondary reference ground through a detection resistor.

[0017] According to another aspect of the invention, an electronic package is provided, comprising a control circuit and an energy distribution switch as described in any of the above embodiments.

[0018] According to another aspect of the present invention, a multi-output voltage power supply system is provided, the voltage power supply system comprising a primary-side switch, a transformer and an electronic package as described above, wherein the primary-side switch is coupled to the primary winding of the transformer, and the electronic package has a detection pin coupled to the secondary winding of the transformer.

[0019] Optionally, the above-mentioned voltage power supply system includes a flyback voltage converter circuit.

[0020] Optionally, the voltage supply system further includes a first diode, a second diode, a first output capacitor located in the first output circuit, and a second output capacitor located in the second output circuit, wherein a first terminal of the energy distribution switch is coupled to the cathode of the first diode, a second terminal of the energy distribution switch is coupled to the first output capacitor to provide a first output voltage, the anode of the first diode is coupled to the secondary winding, the anode of the second diode is coupled to the cathode of the first diode, and the cathode of the second diode is coupled to the second output capacitor to provide a second output voltage.

[0021] Optionally, the voltage supply system further includes an optocoupler that transmits a feedback signal reflecting the second output voltage of the second output circuit to the primary side of the voltage conversion circuit for controlling the primary-side switching to control the energy transferred from the primary side to the secondary side.

[0022] According to another aspect of the present invention, a control circuit for a voltage conversion circuit with multiple outputs is provided. The voltage conversion circuit includes a transformer with a secondary winding and a first output circuit and a second output circuit coupled to the secondary winding for supplying power to two loads respectively. The first output circuit includes an energy distribution switch. The control circuit is characterized by comprising: a turn-on control circuit, which, in a switching cycle, supplies power to the second output circuit first when the voltage conversion circuit supplies power to the secondary side; and a turn-off control circuit, whose input is coupled to the secondary winding, which turns off the energy distribution switch based on the detection of demagnetization of the secondary winding or the primary side switch being turned on.

[0023] According to another aspect of the present invention, a multi-output control method for a multi-output voltage power supply system is proposed. The control method includes: connecting an energy distribution switch in series in a first output circuit to control a first output voltage of the first output circuit and a second output voltage of the second output circuit; detecting a voltage signal on the secondary winding of a voltage conversion circuit or a current signal flowing through the secondary winding, and determining whether a preset condition is met based on the secondary winding signal; when the preset condition is detected, switching the energy distribution switch from a first state to a second state, wherein the preset condition includes demagnetizing the secondary winding or turning on the primary switch of the voltage conversion circuit.

[0024] Optionally, in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, it first supplies power to the second output circuit; when the first output voltage of the first output circuit is detected to be lower than a first preset value, it turns on the energy distribution switch to supply power to the first output circuit; and when a preset condition is detected, it turns off the energy distribution switch; or in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, it first supplies power to the first output circuit; when the second output voltage of the second output circuit is detected to be lower than a second preset value, it turns off the energy distribution switch to supply power to the second output circuit; and when a preset condition is detected, it turns on the energy distribution switch.

[0025] The multi-output voltage power supply system, its control circuit, electronic package, and multi-output control method proposed in this invention can prevent overcharging, solve the voltage stability problem of multi-output, and are applicable to different working modes and frequencies. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and, together with the description, serve to explain embodiments of the invention, but do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 An isolated dual-output power supply system is shown;

[0028] Figure 2 A control circuit 10 for a voltage conversion circuit with multiple outputs according to an embodiment of the present invention is shown;

[0029] Figure 3 An embodiment of a shutdown control circuit according to an embodiment of the present invention is shown;

[0030] Figure 4 A voltage power supply system according to an embodiment of the present invention is shown;

[0031] Figure 5 A voltage power supply system including an electronic package 50 is shown according to an embodiment of the present invention;

[0032] Figure 6 A voltage power supply system employing different rectifier tube configurations is shown according to another embodiment of the present invention;

[0033] Figure 7 A voltage power supply system with a different connection method for the detection pins according to another embodiment of the present invention is shown;

[0034] Figure 8 A voltage power supply system employing different control logic is shown according to another embodiment of the present invention. Detailed Implementation

[0035] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0036] The description in this section pertains to only a few typical embodiments, and the present invention is not limited to the scope of the embodiments described. Combinations of different embodiments, substitution of some technical features in different embodiments, and substitution of similar or identical prior art with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0037] The terms "coupled" or "connected" in this specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection through an electrically conductive medium like a conductor, which may contain parasitic inductance or capacitance. It can also be a connection through intermediate circuits or components described in the embodiments of this specification. Indirect connections may also include connections through other active or passive devices that achieve the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, or other circuits or components. "Multiple" or "more" indicates two or more.

[0038] This invention proposes a voltage conversion circuit with multiple outputs and its control circuit. The voltage conversion circuit includes a transformer with a secondary winding and a first output circuit and a second output circuit coupled to the secondary winding. The first output circuit includes an energy distribution switch. The control circuit is coupled to the secondary winding and determines whether a preset condition is met based on the secondary winding signal. When the preset condition is met, the energy distribution switch is switched from a first state to a second state to distribute energy between the first and second output circuits, preventing overcharging of the second output circuit. Preferably, the preset condition determined based on the secondary winding signal includes detecting demagnetization of the secondary winding or the primary-side switch of the voltage conversion circuit being turned on. The secondary winding signal can be a voltage signal at any end or both ends of the secondary winding, or a current signal flowing through the secondary winding.

[0039] Figure 2A control circuit 10 for a voltage conversion circuit with multiple outputs according to an embodiment of the present invention is shown. In the illustrated embodiment, the voltage conversion circuit includes a flyback voltage conversion circuit. Of course, the voltage conversion circuit can also have other forms, such as a forward voltage conversion circuit, an LLC circuit, etc., or may include other circuit structures. The voltage conversion circuit includes a primary circuit and a secondary circuit, separated by a transformer T. The secondary side of the voltage conversion circuit on the transformer T includes a secondary winding Ls and a first output circuit and a second output circuit coupled to the secondary winding Ls. The first output circuit and the second output circuit are respectively used to provide a first output voltage V1 and a second output voltage V2, which are respectively used to power a first load and a second load. The primary circuit and the secondary circuit can be isolated and use different reference grounds. Of course, the primary circuit and the secondary circuit can also not be isolated and share a reference ground. The first output circuit includes an energy distribution switch Q1, which is used to distribute the energy of the first output circuit and the second output circuit. The second output voltage V2 feeds back the secondary-side feedback signal to the primary-side circuit via optocouplers and other devices, controlling the energy supplied by the primary-side circuit to the secondary-side circuit. Control circuit 10 controls energy distribution switch Q1. Control circuit 10 includes a turn-on control circuit 11 and a turn-off control circuit 12, where turn-on control circuit 11 controls the turn-on of energy distribution switch Q1, and turn-off control circuit 12 controls the turn-off of energy distribution switch Q1. Turn-off control circuit 12 is coupled to the secondary-side winding Ls and controls the turn-off time of energy distribution switch Q1 based on the secondary-side winding signal. The secondary-side winding signal may include a voltage signal or a current signal on the secondary-side winding. In the illustrated embodiment, control circuit 10 has a detection terminal DEM, and turn-off control circuit 12 is coupled to one end of the secondary-side winding Ls through the detection terminal DEM of control circuit 10. This end of the secondary-side winding is the end closest to the positive output, where the positive output is opposite to the secondary-side reference ground. During one switching cycle, when the voltage at the same-name terminal of the secondary winding Ls rises, rectifier diode D2 turns on, and the voltage conversion circuit begins to supply power to the secondary side. At this time, energy distribution switch Q1 is in the off state, and the system first supplies power to the second output circuit, causing the second output voltage V2 to rise. (Of course, the same-name terminal here is relative to the same-name terminal shown on the primary winding; for the other end of the primary winding, this winding end closer to the positive output terminal is the opposite-name terminal.) When the turn-on control circuit 11 detects that the first condition is met, the turn-on control circuit 11 outputs a valid turn-on control signal ON, such as a high-level pulse, to turn on the energy distribution switch Q1 to supply power to the first output circuit, causing the first output voltage V1 to rise. When the turn-off control circuit 12 detects that the second condition is met, the turn-off control circuit 12 outputs a valid turn-off control signal OFF to turn off the energy distribution switch Q1. The valid state can be a high-level pulse or other forms. Preferably, the second output voltage V2 is higher than the first output voltage V1.In one embodiment, the first condition includes a first output voltage V1 being lower than a preset voltage. Specifically, in one switching cycle, the second output circuit is first charged. When the first output voltage V1 provided by the first output circuit is lower than the preset value, the energy distribution switch Q1 is turned on to supply power to the first output circuit. In one embodiment, the second condition includes demagnetization of the secondary winding Ls. Specifically, the moment when the current flowing through the secondary winding Ls or through the energy distribution switch Q1 decreases to zero is detected. When demagnetization of the secondary winding Ls is detected, or after a predetermined time following demagnetization, the energy distribution switch Q1 is turned off. In another embodiment, the second condition includes detecting the on-time of the primary switch by detecting the voltage signal on the secondary winding. When the primary switch is detected to be on, or after a predetermined time following its on-time, the energy distribution switch Q1 is turned off. In one embodiment, the voltage conversion circuit operates in discontinuous current mode. When the current flowing through the secondary winding gradually decreases to zero, the energy distribution switch Q1 is turned off, preventing excess energy from flowing into the second output voltage and eliminating the drawback of overvoltage in the second output voltage V2. In one embodiment, the voltage conversion circuit operates in discontinuous current mode. When the primary-side switch is detected to be on, the energy distribution switch Q1 is turned off. At this time, the secondary-side current is zero, and there is no overcharging of the second output voltage V2. In another embodiment, the voltage conversion circuit operates in continuous current mode. When the on-time of the primary-side switch is detected by detecting the voltage on the secondary winding Ls, the energy distribution switch Q1 is turned off. At this time, the voltage on the secondary winding Ls is negative, no current flows, and there is no overcharging of the second output voltage V2. Through such control, the first and second output voltages can be controlled simultaneously, and it can be ensured that the energy distribution switch Q1 is turned off when the current in the secondary circuit is zero, avoiding the problem of overvoltage of the second output voltage.

[0040] Figure 3An embodiment of a turn-off control circuit according to an embodiment of the present invention is shown. The turn-off control circuit includes a primary-side circuit state detection circuit 31, a demagnetization detection circuit 32, and an OR gate 33. Both the primary-side circuit state detection circuit 31 and the demagnetization detection circuit 32 are coupled to the secondary winding and are used to acquire a signal S1 indicating the primary-side switch of the voltage conversion circuit is on and a signal S2 indicating the secondary winding is demagnetized, respectively. In one embodiment, when the primary-side circuit state detection circuit 31 detects that the primary-side switch is on, signal S1 outputs a high-level pulse. In another embodiment, when the demagnetization detection circuit 32 detects that the secondary current has decreased to zero, signal S2 outputs a high-level pulse. The primary-side circuit state detection circuit 31 and the demagnetization detection circuit 32 can be implemented using any suitable circuit. The first input of the OR gate 33 receives the signal S1 indicating the primary-side switch of the voltage conversion circuit is on, the second input of the OR gate receives the signal S2 indicating the secondary winding is demagnetized, and the output of the OR gate 33 provides a turn-off control signal OFF. In this way, whether the demagnetization state of the secondary winding or the conduction state of the primary switch is detected, the shutdown control circuit can output a valid shutdown control signal OFF. Thus, regardless of whether the voltage conversion circuit operates in discontinuous current mode, continuous current mode, or quasi-resonant current mode, it can shut down the energy distribution switch Q1 when the secondary current flowing through the secondary winding is zero, effectively distributing energy and preventing excess energy from being allocated to the second output circuit, thus preventing overcharging of the second output voltage V2 and improving the stability of system control. This method can effectively improve the stability of the system in terms of start-up, steady-state, dynamic, and cross-regulation. Furthermore, the main control chip can adapt to different operating frequencies for different primary switches, eliminating the need for window time modulation and simplifying design and workflow.

[0041] Figure 4 A voltage power supply system according to an embodiment of the present invention is illustrated. The voltage power supply system includes a voltage conversion circuit and a control circuit 20. In the illustrated embodiment, the voltage conversion circuit is a flyback voltage conversion circuit, including a primary-side switch Qp, a transformer T1, a first rectifier D1, a second rectifier D2, and an energy distribution switch Q1. The transformer T1 includes a primary-side winding Lp and a secondary-side winding Ls. One end of the primary-side winding Lp is coupled to the input voltage, and the other end is coupled to the primary-side switch Qp. The secondary-side circuit includes a first output circuit and a second output circuit. In the illustrated embodiment, the first output circuit includes the first rectifier D1, the energy distribution switch Q1, and a first output capacitor C1, for providing a first output voltage V1. The second output circuit includes the second rectifier D2 and the second output capacitor C2, for providing a second output voltage V2.

[0042] In the illustrated embodiment, the energy distribution switch Q1 is an N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Its drain is coupled to the secondary winding Ls through the first rectifier diode D1, its source is coupled to the first output capacitor C1 and the output terminal of the first output circuit, and its controller is coupled to the output terminal of the control circuit 20. In other embodiments, the energy distribution switch can also use other switching devices, such as JFET (Junction Field-Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor).

[0043] The voltage power supply system further includes an optocoupler OC, which transmits the secondary-side feedback signal reflecting the second output voltage V2 of the second output circuit to the primary side of the voltage conversion circuit to control the primary-side switch Qp, thereby controlling the energy transferred from the primary-side circuit to the secondary-side circuit.

[0044] In another embodiment, the first condition for turning on the energy distribution switch includes the second output voltage V2 rising to a preset value. The optocoupler OC transmits the secondary-side feedback signal reflecting the first output voltage V1 to the primary side to control the primary-side switch Qp, thereby controlling the energy transferred from the primary-side circuit to the secondary-side circuit.

[0045] The control circuit 20 includes a first comparator circuit 21, a second comparator circuit 22, a trigger circuit 23, and a drive circuit 24. The first comparator circuit 21 constitutes the turn-off detection circuit itself or is part of the turn-off detection circuit; that is, the turn-off detection circuit includes the first comparator circuit 21. The first input terminal of the first comparator circuit 21 is coupled to the secondary winding Ls through the detection terminal DEM of the control circuit 20. The second input terminal of the first comparator circuit 21 is coupled to a threshold signal Vref1. The output terminal of the first comparator circuit provides a turn-off control signal OFF. The turn-on detection circuit includes the second comparator circuit 22. In the illustrated embodiment, the first input terminal of the second comparator circuit 22 is coupled to the output terminal of the first output circuit to receive a feedback signal of the first output voltage V1. The second input terminal of the second comparator circuit 22 receives a reference signal Vref2. The output terminal of the second comparator circuit 22 provides a turn-on control signal ON. The first input terminal of the trigger circuit 23 is coupled to the output terminal of the turn-on control circuit, the second input terminal of the trigger circuit 23 is coupled to the output terminal of the turn-off control circuit, the output terminal of the trigger circuit 23 is coupled to the input terminal of the drive circuit 24, and the output terminal of the drive circuit 24 is coupled to the control terminal of the energy distribution switch Q1. The first comparator circuit 21 is used to detect the conduction of the primary-side switch. When the terminal voltage of the secondary winding Ls is lower than the preset threshold signal Vref1, it indicates that the primary-side switch Qp is detected to be on. The turn-off control signal OFF output by the first comparator circuit 21 is valid and is used to make the trigger circuit 23 output an invalid value (such as a low-level logic signal), which is then controlled by the drive circuit 24 to turn off the energy distribution switch Q1. At this time, the energy distribution switch Q1 is turned off. Since the primary-side switch Qp is already on, the voltage on the secondary winding LS causes the secondary rectifier to be cut off. No current flows through the secondary winding, and there is no more excess energy to charge the capacitor in the second output circuit. Therefore, the second voltage will not be overcharged, the energy distribution mode is stable, and the cross-regulation rate is effectively adjusted. When the first output voltage V1 is less than the preset threshold represented by Vref2, the ON control signal output by the second comparator circuit 22 is valid and is used to make the trigger circuit 23 output a valid value (such as a high-level logic signal), which is amplified by the drive circuit 24 to control the energy distribution switch Q1 to turn on.

[0046] In one embodiment, the control circuit 20 is fabricated on a semiconductor substrate to form a semiconductor wafer. In another embodiment, the control circuit 20 is fabricated in an electronic package. In yet another embodiment, the semiconductor wafer on which the control circuit 20 is fabricated and the power distribution switch Q1 are fabricated in the same electronic package.

[0047] Figure 5A voltage power supply system according to an embodiment of the present invention is shown. The voltage power supply system includes a primary circuit, a transformer T1, a secondary circuit, and an electronic package 50. The primary circuit includes a primary switch Qp coupled to the primary winding Lp of the transformer T1. The secondary circuit includes a first diode D1, a second diode D2, a first output capacitor C1 located in a first output circuit, a second output capacitor C2 located in a second output circuit, an optocoupler OC, and the electronic package 50. The electronic package 50 includes a control circuit and an energy distribution switch as described in any of the above embodiments. The first terminal of the energy distribution switch is coupled to the cathode of the first diode D1, and the second terminal of the energy distribution switch is coupled to the first output capacitor C1 to provide a first output voltage V1. The anode of the first diode D1 is coupled to the anode of the second diode D2 and the secondary winding Ls, and the cathode of the second diode D2 is coupled to the second output capacitor C2 to provide a second output voltage V2.

[0048] The first rectifier diode D1 and the second rectifier diode D2 can also adopt a synchronous rectification method different from that of diodes.

[0049] The first rectifier tube D1 and the second rectifier tube D2 can also be positioned in different ways, such as using Figure 6 The settings.

[0050] Figure 6 A voltage power supply system employing different rectifier diode configurations according to another embodiment of the present invention is shown, wherein the anode of the second diode D2 is coupled to the cathode of the first diode D1. Specifically, the secondary circuit of the voltage power supply system includes a control circuit 60, an energy distribution switch Q1, a first diode D1, a second diode D2, a first output capacitor C1 located in the first output circuit, a second output capacitor C2 located in the second output circuit, and an optocoupler OC, etc. The first terminal of the energy distribution switch Q1 is coupled to the cathode of the first diode D1, and the second terminal of the energy distribution switch Q1 is coupled to the first output capacitor C1 to provide a first output voltage V1. The anode of the first diode D1 is coupled to the secondary winding Ls. The anode of the second diode D2 is coupled to the cathode of the first diode D1, and the cathode of the second diode D2 is coupled to the second output capacitor C2 to provide a second output voltage V2. In this manner, the second diode D2 can be a common non-voltage-resistant diode, reducing manufacturing costs.

[0051] In another embodiment, it can be Figure 5 The second diode D2 is positioned between the secondary ground GND and the opposite terminal of the secondary winding Ls.

[0052] In one embodiment, the secondary circuit includes, for example, Figure 5The second diode D2 is used, excluding the first diode D1. When the electronic package 50 detects demagnetization of the secondary winding, it promptly shuts off the energy distribution switch to prevent the first output circuit on the secondary side from discharging through the secondary winding Ls. During the charging process of the second output circuit, it turns on the energy distribution switch when the first condition is met. This approach further reduces external components and lowers the system size.

[0053] continue Figure 5 The electronic package 50 has a detection pin DEM for coupling to the secondary winding of transformer T1. Based on the detection pin DEM, the on-time of the primary switch or the demagnetization state of the secondary winding is detected. Furthermore, based on the signal state on the secondary winding, the off-time of the energy distribution switch is controlled to optimize energy distribution and cross-regulation, eliminating overcharging of the second output voltage V1.

[0054] The electronic package 50 may further include a ground pin GND, a voltage input pin DRAIN, an output pin VO, and a feedback pin FB. The ground pin GND is used to couple to the secondary reference ground. The voltage input pin DRAIN is externally coupled to the cathode of the diode D1 and internally coupled to the first terminal of the energy distribution switch. The second terminal of the energy distribution switch is coupled to the output pin VO. The feedback pin FB is used to input the feedback signal of the first output voltage V1 into the control circuit.

[0055] The electronic package 50 may further include a power supply pin VDD for coupling to a second output circuit and receiving a second output voltage V2 for powering the control circuit.

[0056] The electronic package 50 may further include a compensation pin COMP and a reference pin VREF for coupling the optocoupler OC of the secondary circuit to adjust the compensation amount of the feedback loop.

[0057] During one switching cycle, the primary-side switch Qp is turned on, increasing the current in the primary-side winding Lp. The secondary-side winding Ls is turned off due to the reverse bias of rectifier diodes D1 and D2, and the energy distribution switch on the secondary side is turned off. When the primary-side switch Qp switches from on to off, diode D2 turns on, and the voltage conversion circuit supplies power to the secondary side. Since the energy distribution switch is off, the secondary-side current flows through diode D2 to first supply power to the second output circuit, causing voltage V2 to rise. When the first condition is met, such as the first output voltage V1 being lower than a preset threshold, the energy distribution switch is turned on to supply power to the first output circuit, causing the first output voltage V1 to rise. The voltage or current signal on the secondary-side winding Ls of the voltage conversion circuit is detected, and the energy distribution switch is turned off when the second condition is met. In one embodiment, the second condition includes detecting that the primary-side switch of the voltage conversion circuit is turned on. When the voltage at the upper terminal of the secondary winding Ls (connected to the detection pin DEM of the electronic package 50) is lower than a preset threshold, if it is lower than the secondary reference ground voltage, it indicates that the primary-side switch Qp is turned on and the energy distribution switch is turned off. At this time, turning off the energy distribution switch will ensure that no current flows through the diode D2 to charge the second output capacitor C2, preventing the second output voltage V2 from being overcharged.

[0058] In another implementation, the second condition includes detecting demagnetization of the secondary winding, and turning off the energy distribution switch when the current flowing through the secondary winding Ls is detected to drop to zero.

[0059] In one embodiment, the energy distribution switch is promptly shut off upon detection of any of the aforementioned states to accommodate various situations.

[0060] In another embodiment, the energy distribution switch is turned off after a predetermined time delay following detection of demagnetization of the secondary winding.

[0061] Through the above control methods and settings, the system can be used to optimize energy distribution, eliminate overcharging of the second output voltage V2, improve cross regulation, and the system has a simplified structure and simple control.

[0062] Figure 7 A voltage power supply system according to another embodiment of the present invention is shown. Relative to... Figure 5 In one embodiment, the secondary side of the voltage-powered system includes a sensing resistor Rs coupled between the secondary ground GND and the secondary winding Ls. The sensing pin DEM of the packaged electronics 70 is coupled to the near-reference ground terminal of the secondary winding Ls of transformer T1 to obtain the voltage across the sensing resistor Rs. This voltage reflects the current flowing through the secondary winding Ls and can be used to determine the demagnetization time of the secondary winding Ls, thereby controlling the switching time of the energy distribution switch and controlling the energy distribution between the two output circuits.

[0063] The above embodiments provide a multi-output control method for a multi-output voltage power supply system, including, in one step, connecting an energy distribution switch in series in a first output circuit to control the first output voltage of the first output circuit and the second output voltage of the second output circuit; and in another step, detecting the voltage signal on the secondary winding of the voltage conversion circuit or the current signal flowing through the secondary winding, and determining whether a preset condition is met based on the secondary winding signal; when the preset condition is detected, switching the energy distribution switch from an on state to an off state, wherein the preset condition includes demagnetizing the secondary winding or turning on the primary switch of the voltage conversion circuit.

[0064] Figure 8 A voltage power supply system according to another embodiment of the present invention is shown. In this embodiment, during a switching cycle, when the voltage conversion circuit supplies power to the secondary side, it first supplies power to the first output circuit. When it is detected that the second output voltage of the second output circuit is lower than a second preset value, the energy distribution switch is turned off to supply power to the second output circuit, and when a preset condition is detected, the energy distribution switch is switched from the off state to the on state. Figure 8As shown, the voltage power supply system includes a voltage conversion circuit with multiple outputs and a control circuit 80. The voltage conversion circuit includes a secondary winding Ls on the secondary side, and a first output circuit and a second output circuit coupled to the secondary winding Ls. The first output circuit provides a first output voltage V1, and the second output circuit provides a second output voltage V2. The first output circuit includes an energy distribution switch Q1. The voltage conversion circuit includes an optocoupler OC, used to feed back the secondary side feedback signal reflecting the first output voltage V1 to the primary side, controlling the primary side switch Qp, thereby controlling the energy output to the secondary side and controlling the first output voltage V1. The control circuit 80 is coupled to the secondary winding Ls and determines whether a preset condition is met based on the secondary winding Ls signal. When the preset condition is detected, the energy distribution switch Q1 is switched from the off state to the on state. Similar to the above embodiment, the preset condition includes demagnetizing the secondary winding or turning on the primary side switch of the voltage conversion circuit. Specifically, the control circuit 80 includes a turn-off control circuit and a turn-on control circuit 82. The turn-off control circuit includes a comparator circuit 81. In one switching cycle, when the voltage conversion circuit supplies power to the secondary side, the energy distribution switch is in the on state, initially supplying power to the first output circuit. When the comparator circuit detects that the second output voltage V2 of the second output circuit is lower than the preset value Vref3, the turn-off control circuit outputs a valid turn-off control signal OFF to turn off the energy distribution switch Q1, so as to supply power to the second output circuit. The input terminal of the turn-on control circuit 82 is coupled to the secondary winding Ls. When the turn-on control circuit 82 detects that a preset condition is met based on the signal state of its input terminal, such as the voltage at the upper terminal (opposite to the near-ground terminal of the secondary winding Ls) being lower than the preset value Vref1, the turn-on control circuit 82 outputs a valid turn-on control signal ON to turn on the energy distribution switch Q1. This method can prevent the remaining energy from continuing to flow to the first output voltage V1 when the energy distribution switch is turned on early under the condition that the off time of the energy distribution switch is fixed, which would cause the first output voltage V1 to be overcharged and cause system control instability.

[0065] Those skilled in the art should know that the logic controls such as "high level" and "low level", "set" and "reset", "AND gate" and "OR gate", "non-inverting input" and "inverting input" in the logic control involved in the specification or drawings can be interchanged or changed, and the same function or purpose as the above embodiment can be achieved by adjusting the subsequent logic control.

[0066] The description and application of the present invention herein are illustrative and not intended to limit the scope of the invention to the embodiments described above. The effects or advantages described in the specification may not be apparent in actual experimental cases due to uncertainties in specific conditions or other factors, and such descriptions are not intended to limit the scope of the invention. Variations and modifications to the embodiments disclosed herein are possible, and various substitutions and equivalents of the components in the embodiments are well known to those skilled in the art. It should be understood by those skilled in the art that the invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of the invention. Other variations and modifications can be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A control circuit for a voltage conversion circuit with multiple outputs, the voltage conversion circuit comprising a transformer with a secondary winding and a first output circuit and a second output circuit coupled to the secondary winding, wherein the first output circuit includes an energy distribution switch and a first diode, the control circuit has a detection terminal, the secondary winding is coupled to the detection terminal of the control circuit and the anode of the first diode, and a first terminal of the energy distribution switch is coupled to the cathode of the first diode, characterized in that, The control circuit includes: In one switching cycle, when the voltage conversion circuit supplies power to the secondary side of the transformer, it first supplies power to the second output circuit. When the conduction control circuit detects that a first condition is met, it outputs a valid conduction control signal to turn on the energy distribution switch to supply power to the first output circuit. The shutdown control circuit has its input terminal coupled to the secondary winding through the detection terminal of the control circuit. When the shutdown control circuit detects that the second condition is met based on the signal of the secondary winding, the shutdown control circuit outputs a valid shutdown control signal to shut down the energy distribution switch. The second condition includes demagnetization of the secondary winding.

2. The control circuit as claimed in claim 1, wherein the shutdown control circuit includes a first comparator circuit, a first input terminal of the first comparator circuit is coupled to a secondary winding for receiving the secondary winding terminal voltage, a second input terminal of the first comparator circuit is coupled to a threshold signal, and the output terminal of the first comparator circuit provides a shutdown control signal.

3. The control circuit as claimed in claim 1, wherein the shutdown control circuit includes an OR gate, the first input terminal of the OR gate receiving a signal reflecting the primary-side switch of the voltage conversion circuit being turned on, and the second input terminal of the OR gate receiving a signal reflecting the secondary-side winding being demagnetized.

4. The control circuit as described in claim 1, wherein the conduction detection circuit includes a second comparison circuit, the second comparison circuit being coupled to the output terminal of the first output circuit, and the first condition including the first output voltage of the first output circuit being lower than a preset voltage.

5. The control circuit as described in claim 1, further comprising: The trigger circuit has its first input terminal coupled to the output terminal of the turn-on control circuit, and its second input terminal coupled to the output terminal of the turn-off control circuit. as well as The input terminal of the drive circuit is coupled to the output terminal of the trigger circuit, and the output terminal of the drive circuit is coupled to the control terminal of the energy distribution switch.

6. A control circuit for a voltage conversion circuit with multiple outputs, the voltage conversion circuit comprising a transformer with a secondary winding and a first output circuit and a second output circuit coupled to the secondary winding, wherein the first output circuit includes an energy distribution switch and a first diode, the control circuit has a detection terminal, the secondary winding is coupled to the detection terminal of the control circuit and the anode of the first diode, and a first terminal of the energy distribution switch is coupled to the cathode of the first diode, characterized in that, The control circuit is coupled to the secondary winding through the detection terminal of the control circuit, and determines whether the preset conditions are met based on the signal of the secondary winding. When the preset conditions are detected, the energy distribution switch is switched from the first state to the second state, wherein the preset conditions include demagnetization of the secondary winding.

7. The control circuit as described in claim 6, wherein the first state of the energy distribution switch is an off state, the second state of the energy distribution switch is an on state, and the control circuit comprises: The shutdown control circuit, including the comparator circuit, in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, first supplies power to the first output circuit. When the comparator circuit detects that the second output voltage of the second output circuit is lower than the preset value, the shutdown control circuit outputs a valid shutdown control signal to shut down the energy distribution switch so as to supply power to the second output circuit. as well as The conduction control circuit has its input terminal coupled to the secondary winding. When the conduction control circuit detects that the preset conditions are met based on the signal from the secondary winding, it outputs a valid conduction control signal to turn on the energy distribution switch.

8. The control circuit as described in claim 6, wherein the detection terminal is coupled to: The upper terminal of the secondary winding; or The near-reference ground terminal of the secondary winding is opposite to the upper terminal, and the near-reference ground terminal of the secondary winding is coupled to the secondary reference ground through a sensing resistor.

9. An electronic package comprising a control circuit and an energy distribution switch as claimed in any one of claims 1-8.

10. A multi-output voltage power supply system, comprising a primary-side switch, a transformer, and an electronic package as described in claim 9, wherein the primary-side switch is coupled to the primary winding of the transformer, and the electronic package has a detection pin coupled to the secondary winding of the transformer.

11. The voltage power supply system as claimed in claim 10, comprising a flyback voltage converter circuit.

12. The voltage power supply system of claim 10, further comprising a second diode, a first output capacitor located in the first output circuit, and a second output capacitor located in the second output circuit, wherein the second terminal of the energy distribution switch is coupled to the first output capacitor to provide a first output voltage, the anode of the first diode is coupled to the secondary winding, the anode of the second diode is coupled to the cathode of the first diode, and the cathode of the second diode is coupled to the second output capacitor to provide a second output voltage.

13. The voltage power supply system of claim 10, further comprising an optocoupler, wherein the optocoupler transmits the secondary-side feedback signal to the primary side of the voltage conversion circuit for controlling the primary-side switching, thereby controlling the energy transmitted from the primary side to the secondary side.

14. A multi-output control method for a multi-output voltage power supply system, comprising: An energy distribution switch is connected in series in the first output circuit to control the first output voltage of the first output circuit and the second output voltage of the second output circuit. The first output circuit includes an energy distribution switch and a first diode. The secondary winding is coupled to the detection terminal of the control circuit and the anode of the first diode. The first terminal of the energy distribution switch is coupled to the cathode of the first diode. as well as The voltage signal on the secondary winding of the voltage conversion circuit or the current signal flowing through the secondary winding is detected by the detection terminal of the control circuit, and it is determined whether the preset conditions are met based on the secondary winding signal. When the preset conditions are detected, the energy distribution switch is switched from the first state to the second state, wherein the preset conditions include demagnetization of the secondary winding.

15. The control method as described in claim 14, wherein in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, the second output circuit is supplied first; when the first output voltage of the first output circuit is detected to be lower than a first preset value, the energy distribution switch is turned on to supply power to the first output circuit; when the preset condition is met, the energy distribution switch is turned off.

16. The control method as described in claim 14, wherein in one switching cycle, when the voltage conversion circuit supplies power to the secondary side, the first output circuit is supplied first; when the second output voltage of the second output circuit is detected to be lower than the second preset value, the energy distribution switch is turned off to supply power to the second output circuit; when the preset condition is met, the energy distribution switch is turned on.

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