Double-transistor flyback switching power supply

Abstract

The invention relates to the technical field of switching power supplies, in particular to a double-transistor flyback switching power supply, a PFC (Power Factor Correction) module consists of a PFC chip U1 and a peripheral circuit thereof, the peripheral circuit of the PFC chip U1 is provided with a quick start circuit, and the quick start circuit is integrally packaged in the PFC chip U1; the auxiliary driving module is composed of a double-tube driving chip U2 and a peripheral circuit thereof, and a double-tube circuit is integrated and packaged in the double-tube driving chip U2; the main driving module is composed of a single-tube driving chip U3 and a peripheral circuit thereof, the single-tube driving chip U3 is additionally provided with a switching signal end, and the switching signal end is electrically connected with the input end of the double-tube driving chip U2; the problem that control is difficult when a single chip drives double tubes is solved, and the problems that the number of peripheral circuit discrete components of multiple chips in a switching power supply is large, the space of a circuit board is occupied, and the production efficiency is low are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, in particular to a dual-tube flyback switching power supply. Background Art

[0002] Currently, to achieve ultra-high efficiency in switching power supplies for LED drivers, a PFC+dual-switch flyback (i.e., dual-switch quasi-resonant flyback) solution has been proposed. This power conversion topology doubles the power consumption, improving the switching power supply's performance in terms of energy efficiency, EMC, and temperature rise. This significantly broadens its application scope and significantly alleviates customers' concerns about power limitations. More importantly, the PFC+dual-switch flyback solution offers higher power density than the PFC+LLC or PFC+single-switch flyback solutions.

[0003] However, existing dual-switch flyback switching power supplies typically utilize a KP2202B + KP85405 chip combination framework, with both the upper and lower switches controlled by the KP85405 chip. This results in complex dual-switch control logic and concentrated heat. Furthermore, the peripheral circuitry of existing switching power supplies utilizes discrete components, which consumes significant circuit board space. Furthermore, the manufacturing process for the switching power supply circuit boards requires constant insertion, installation, and soldering of discrete components, resulting in low production efficiency. Summary of the Invention

[0004] In view of the above-mentioned defects, the purpose of the present invention is to propose a dual-switch flyback switching power supply, which solves the problem of difficulty in controlling dual-switch drives with a single chip, as well as the problem that the peripheral circuits of multiple chips in the switching power supply have many discrete components, occupy circuit board space, and have low production efficiency.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A dual-switch flyback switching power supply, comprising a PFC module, an auxiliary drive module, a main drive module, a dual-switch circuit, and a transformer T1; the PFC module is electrically connected to the auxiliary drive module and the main drive module, respectively; the auxiliary drive module is electrically connected to the primary winding of the transformer T1 via the dual-switch circuit; and the main drive module is electrically connected to the primary winding of the transformer T1;

[0007] The PFC module is composed of a PFC chip U1 and its peripheral circuits. The peripheral circuits of the PFC chip U1 are provided with a fast start-up circuit, which is integrated and packaged in the PFC chip U1.

[0008] The auxiliary drive module is composed of a dual-tube drive chip U2 and its peripheral circuits, and the dual-tube circuits are integrated and packaged in the dual-tube drive chip U2;

[0009] The main driving module is composed of a single-tube driving chip U3 and its peripheral circuits. The single-tube driving chip U3 is additionally provided with a switch signal terminal, and the switch signal terminal is electrically connected to the input terminal of the dual-tube driving chip U2.

[0010] Furthermore, the fast startup circuit includes a MOS transistor Q1, a resistor R1, a resistor R2, a voltage regulator DZ1, and a diode D10; one end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R1 and the gate of the MOS transistor Q1 are electrically connected to the cathode of the voltage regulator DZ1, the anode of the voltage regulator DZ1 is grounded, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is electrically connected to the anode of the diode D10, and the cathode of the diode D10 is electrically connected to the power supply terminal of the PFC chip U1;

[0011] One end of the resistor R1 is used as a new pin HV end of the PFC chip U1, which is used to be electrically connected to the VBUS power supply bus.

[0012] Furthermore, the model of the PFC chip U1 is OB3674.

[0013] Furthermore, the dual-tube circuit includes a resistor R20, a resistor R21, a resistor R22, a resistor R23, a MOS transistor Q3, and a MOS transistor Q4; one end of the resistor R22 is electrically connected to the high-order output terminal of the dual-tube driver chip U2, the other end of the resistor R22 and one end of the resistor R23 are both electrically connected to the gate of the MOS transistor Q4, the other end of the resistor R23 and the source of the MOS transistor Q4 are both electrically connected to the drain of the MOS transistor Q3, the gate of the MOS transistor Q3 and one end of the resistor R21 are both electrically connected to one end of the resistor R20, the other end of the resistor R21 and the source of the MOS transistor Q3 are both grounded, and the other end of the resistor R20 is electrically connected to the low-order output terminal of the dual-tube driver chip U2;

[0014] The low-order output pin of the dual-tube driver chip U2 is canceled, the drain of the MOS tube Q4 replaces the high-order output pin of the dual-tube driver chip U2 as a pin, and the source of the MOS tube Q4 replaces the high-voltage floating power supply terminal of the dual-tube driver chip U2 as a pin.

[0015] Furthermore, the model of the dual-tube driver chip U2 is BP6914.

[0016] Furthermore, the gate of the built-in MOS tube of the single-tube driver chip U3 is led out to serve as the switch signal terminal.

[0017] Furthermore, the model of the single-tube driver chip U3 is BP3187.

[0018] Furthermore, it also includes a synchronous rectification module; the secondary winding of the transformer T1 is electrically connected to the synchronous rectification module;

[0019] The synchronous rectification module is formed by integrating and packaging the synchronous rectification chip U4 and its peripheral circuits.

[0020] Furthermore, the model of the synchronous rectification chip U4 is KP4050.

[0021] The technical solution provided by the present invention can include the following beneficial effects: the dual-tube flyback circuit architecture is mainly composed of an auxiliary drive module, a main drive module and a dual-tube circuit, the auxiliary drive module controls the upper switch tube (such as a MOS tube) of the dual-tube circuit, and the main drive module controls the lower switch tube of the dual-tube circuit. The advantage of independently controlling the upper and lower tubes is that the voltage stress of the switch tube is reduced, the efficiency of the power supply is improved, the control logic design is easy, the heat is more dispersed, and the switching power supply with the same parameters can be expanded to design a higher power. Based on this, the auxiliary drive module and the main drive module preferably use a dual-tube driver chip U2 and a single-tube driver chip U3 respectively. The dual-tube driver chip U2 can drive two switch tubes, and the single-tube driver chip U3 can link the dual-tube driver chip U2 to control the two switch tubes separately by adding a switch signal terminal.

[0022] At the same time, in order to reduce the number of discrete components and the space occupied by the circuit board and improve production efficiency, the quick start circuit of the PFC chip U1 peripheral circuit is integrated and packaged into the PFC chip U1 to form a new PFC chip U1; the dual-tube circuit directly driven by the dual-tube driver chip U2 is integrated and packaged into the dual-tube driver chip U2 to form a new dual-tube driver chip U2; so that in the future, when producing switching power supplies, the new PFC chip U1 and the new dual-tube driver chip U2 can be directly used without adjusting the inherent functional circuits of the chip periphery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a circuit of a dual-tube flyback switching power supply according to one embodiment of the present invention. Figure 1 .

[0024] Figure 2 Yes Figure 1 The circuit diagram shown is before the PFC chip U1 integrates the fast startup circuit.

[0025] Figure 3 Yes Figure 1 The circuit diagram shown is before the dual-tube driver chip U2 is integrated into the dual-tube circuit.

[0026] Figure 4 Yes Figure 1 The internal circuit diagram of the PFC chip U1 after integrating the fast startup circuit is shown.

[0027] Figure 5 Yes Figure 1 The internal circuit diagram of the dual-tube driver chip U2 before integrating the dual-tube circuit is shown.

[0028] Figure 6 Yes Figure 1 The internal circuit diagram of the dual-tube driver chip U2 after integrating the dual-tube circuit is shown.

[0029] Figure 7 Yes Figure 1 The internal circuit diagram of the single-tube driver chip U3 after adding a switch signal terminal.

[0030] Figure 8 Yes Figure 1 The circuit of a dual-tube flyback switching power supply is shown Figure 2 .

[0031] Among them: PFC module 1, auxiliary drive module 2, main drive module 3, dual-tube circuit 4, transformer T1, PFC chip U1, fast start circuit 1, dual-tube drive chip U2, single-tube drive chip U3, switch signal terminal 31, MOS tube Q1, resistor R1, resistor R2, voltage regulator DZ1, diode D10, resistor R20, resistor R21, resistor R22, resistor R23, MOS tube Q3, MOS tube Q4, synchronous rectifier module 5, synchronous rectifier chip U4. DETAILED DESCRIPTION

[0032] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0033] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically specified.

[0034] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal communication between two components or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0035] The following combination Figures 1 to 8 , describing a dual-switch flyback switching power supply according to an embodiment of the present invention.

[0036] A dual-switch flyback switching power supply includes a PFC module 1, an auxiliary drive module 2, a main drive module 3, a dual-switch circuit 4, and a transformer T1. The PFC module 1 is electrically connected to the auxiliary drive module 2 and the main drive module 3, respectively. The auxiliary drive module 2 is electrically connected to the primary winding of the transformer T1 via the dual-switch circuit 4. The main drive module 3 is electrically connected to the primary winding of the transformer T1.

[0037] The PFC module 1 is composed of a PFC chip U1 and its peripheral circuits. The peripheral circuits of the PFC chip U1 are provided with a fast start-up circuit 1, which is integrated and packaged in the PFC chip U1.

[0038] The auxiliary drive module 2 is composed of a dual-tube drive chip U2 and its peripheral circuits, and the dual-tube circuit 4 is integrated and packaged in the dual-tube drive chip U2;

[0039] The main driving module 3 is composed of a single-transistor driving chip U3 and its peripheral circuits. The single-transistor driving chip U3 is additionally provided with a switch signal terminal 31 , which is electrically connected to the input terminal of the dual-transistor driving chip U2 .

[0040] The present invention proposes a preferred embodiment of a dual-tube flyback switching power supply, such as Figure 1 As shown, the dual-tube flyback circuit architecture is mainly composed of an auxiliary drive module 2, a main drive module 3 and a dual-tube circuit 4. The auxiliary drive module 2 controls the upper switch tube (such as a MOS tube) of the dual-tube circuit 4, and the main drive module 3 controls the lower switch tube of the dual-tube circuit 4. The advantage of independent control of the upper and lower tubes is that it reduces the voltage stress of the switch tube, improves the efficiency of the power supply, facilitates control logic design, and disperses heat. The switching power supply with the same parameters can be expanded to design a higher power. Based on this, the auxiliary drive module 2 and the main drive module 3 preferably use a dual-tube driver chip U2 and a single-tube driver chip U3 respectively. The dual-tube driver chip U2 can drive two switch tubes. The single-tube driver chip U3 can link the dual-tube driver chip U2 to control the two switch tubes respectively by adding a switch signal terminal 31.

[0041] At the same time, in order to reduce the number of discrete components and the space occupied by the circuit board, and improve production efficiency, the fast start circuit 1 of the PFC chip U1 peripheral circuit is integrated and packaged into the PFC chip U1 to form a new PFC chip U1 (before integration, the connection relationship between the fast start circuit 1 and the PFC chip U1 is as follows: Figure 2 The dual-tube circuit 4 directly driven by the dual-tube driver chip U2 is integrated and packaged in the dual-tube driver chip U2 to form a new dual-tube driver chip U2 (before integration, the connection relationship between the dual-tube circuit 4 and the dual-tube driver chip U2 is as follows); Figure 3 As shown); Therefore, in the future, when producing switching power supplies, the new PFC chip U1 and the new dual-tube driver chip U2 can be directly used without adjusting the inherent functional circuits around the chip.

[0042] Furthermore, the fast start circuit 1 includes a MOS transistor Q1, a resistor R1, a resistor R2, a voltage regulator DZ1, and a diode D10; one end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R1 and the gate of the MOS transistor Q1 are electrically connected to the cathode of the voltage regulator DZ1, the anode of the voltage regulator DZ1 is grounded, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is electrically connected to the anode of the diode D10, and the cathode of the diode D10 is electrically connected to the power supply terminal of the PFC chip U1;

[0043] One end of the resistor R1 is used as a new pin HV end of the PFC chip U1 for being electrically connected to the VBUS power supply bus.

[0044] In this embodiment, Figure 4 As shown, when the fast start circuit 1 is integrated into the PFC chip U1, it is preferred that the resistor R4 and the resistor R5 are replaced by the MOS tube Q1, the resistor R1, the resistor R2, the voltage regulator DZ1 and the diode D10 (as shown in FIG. Figure 4 The part in the red frame is integrated into the PFC chip U1; the MOS tube Q1 is used as the core for the fast startup circuit 1, which has a faster startup speed and less loss than the resistor.

[0045] Furthermore, the model of the PFC chip U1 is OB3674.

[0046] In this embodiment, the PFC chip U1 only needs to have a power supply terminal (ie, VDD) to integrate the fast startup circuit 1 inside the chip. For example, the PFC chip U1 of model OB3674 has stable performance and is often selected as the PFC chip U1. Figure 4 The area outside the red box is the original internal circuit of the OB3674 chip.

[0047] Furthermore, the dual-tube circuit 4 includes a resistor R20, a resistor R21, a resistor R22, a resistor R23, a MOS transistor Q3, and a MOS transistor Q4; one end of the resistor R22 is electrically connected to the high-order output terminal of the dual-tube driver chip U2, the other end of the resistor R22 and one end of the resistor R23 are electrically connected to the gate of the MOS transistor Q4, the other end of the resistor R23 and the source of the MOS transistor Q4 are electrically connected to the drain of the MOS transistor Q3, the gate of the MOS transistor Q3 and one end of the resistor R21 are electrically connected to one end of the resistor R20, the other end of the resistor R21 and the source of the MOS transistor Q3 are grounded, and the other end of the resistor R20 is electrically connected to the low-order output terminal of the dual-tube driver chip U2;

[0048] The low-order output pin of the dual-tube driver chip U2 is canceled, the drain of the MOS tube Q4 replaces the high-order output pin of the dual-tube driver chip U2 as the pin, and the source of the MOS tube Q4 replaces the high-voltage floating power supply pin of the dual-tube driver chip U2 as the pin.

[0049] In this embodiment, Figure 5 This is the original internal circuit of the dual-tube driver chip U2, such as Figure 6 In order to integrate the dual-tube circuit 4 into the internal circuit of the dual-tube driver chip U2, the low-order output terminal (LO) pin of the dual-tube driver chip U2 is cancelled after the integration, and the drain of the MOS tube Q4 replaces the high-order output terminal (HO) of the dual-tube driver chip U2 as the pin (HV), and the source of the MOS tube Q4 replaces the high-voltage floating power supply terminal of the dual-tube driver chip U2 as the pin (VS), thereby forming a new dual-tube driver chip U2.

[0050] Furthermore, the model of the dual-tube driver chip U2 is BP6914.

[0051] In this embodiment, the model of the dual-tube driver chip U2 is preferably BP6914, which has dual MOS tubes built in, and has a high-level output terminal (HO), a high-voltage floating power supply terminal (VS) and a low-level output terminal (LO), and has the conditions for integrating the dual-tube circuit 4.

[0052] Furthermore, the gate of the built-in MOS transistor of the single-tube driver chip U3 is led out to serve as a switch signal terminal 31 .

[0053] Furthermore, the model of the single-tube driver chip U3 is BP3187.

[0054] In this embodiment, the model of the single-tube driver chip U3 is preferably BP3187, and its internal circuit is as follows: Figure 7 As shown, the single-tube driver chip U3 controls the switch tube through the built-in MOS tube. When the single-tube driver chip U3 is linked with the dual-tube driver chip U2, the gate of the built-in MOS tube of the single-tube driver chip U3 can be brought out and used as the switch signal terminal 31 (SIGNAL).

[0055] Furthermore, it also includes a synchronous rectification module 5; the secondary winding of the transformer T1 is electrically connected to the synchronous rectification module 5;

[0056] The synchronous rectification module 5 is formed by integrating and packaging the synchronous rectification chip U4 and its peripheral circuits.

[0057] Furthermore, the model of the synchronous rectification chip U4 is KP4050.

[0058] In this embodiment, Figure 8 As shown, the model of the synchronous rectifier chip U4 is preferably KP4050, which is commonly used to drive the MOS tube Q6 to achieve synchronous rectification. The function of this module is single. When the output end of the switching power supply adopts synchronous rectification, the synchronous rectifier chip U4 and its peripheral circuits can be integrated and packaged into a synchronous rectifier module 5, which can be directly connected in series with the secondary winding of the transformer T1 to improve the production efficiency of the switching power supply.

[0059] Other structures and operations of a dual-switch flyback switching power supply according to an embodiment of the present invention are well known to those skilled in the art and will not be described in detail here.

[0060] Throughout this specification, reference to terms such as "embodiment" or "example" indicates that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A dual-switch flyback switching power supply, characterized in that: The invention comprises a PFC module, an auxiliary drive module, a main drive module, a dual-tube circuit and a transformer T1; the PFC module is electrically connected to the auxiliary drive module and the main drive module respectively, the auxiliary drive module is electrically connected to the primary winding of the transformer T1 via the dual-tube circuit, and the main drive module is electrically connected to the primary winding of the transformer T1; The PFC module is composed of a PFC chip U1 and its peripheral circuits. The peripheral circuits of the PFC chip U1 are provided with a fast start-up circuit, which is integrated and packaged in the PFC chip U1. The auxiliary drive module is composed of a dual-tube drive chip U2 and its peripheral circuits, and the dual-tube circuits are integrated and packaged in the dual-tube drive chip U2; The main driving module is composed of a single-tube driving chip U3 and its peripheral circuits. The single-tube driving chip U3 is additionally provided with a switch signal terminal, and the switch signal terminal is electrically connected to the input terminal of the dual-tube driving chip U2.

2. The dual-switch flyback switching power supply according to claim 1, characterized in that: The fast startup circuit includes a MOS transistor Q1, a resistor R1, a resistor R2, a voltage regulator DZ1, and a diode D10; one end of the resistor R1 is electrically connected to one end of the resistor R2, the other end of the resistor R1 and the gate of the MOS transistor Q1 are electrically connected to the cathode of the voltage regulator DZ1, the anode of the voltage regulator DZ1 is grounded, the other end of the resistor R2 is electrically connected to the drain of the MOS transistor Q1, the source of the MOS transistor Q1 is electrically connected to the anode of the diode D10, and the cathode of the diode D10 is electrically connected to the power supply terminal of the PFC chip U1; One end of the resistor R1 is used as a new pin HV end of the PFC chip U1, which is used to be electrically connected to the VBUS power supply bus.

3. The dual-switch flyback switching power supply according to claim 1, wherein: The model of the PFC chip U1 is OB3674.

4. The dual-switch flyback switching power supply according to claim 1, wherein: The dual-tube circuit includes a resistor R20, a resistor R21, a resistor R22, a resistor R23, a MOS transistor Q3, and a MOS transistor Q4; one end of the resistor R22 is electrically connected to the high-order output terminal of the dual-tube driver chip U2, the other end of the resistor R22 and one end of the resistor R23 are both electrically connected to the gate of the MOS transistor Q4, the other end of the resistor R23 and the source of the MOS transistor Q4 are both electrically connected to the drain of the MOS transistor Q3, the gate of the MOS transistor Q3 and one end of the resistor R21 are both electrically connected to one end of the resistor R20, the other end of the resistor R21 and the source of the MOS transistor Q3 are both grounded, and the other end of the resistor R20 is electrically connected to the low-order output terminal of the dual-tube driver chip U2; The low-order output pin of the dual-tube driver chip U2 is canceled, the drain of the MOS tube Q4 replaces the high-order output pin of the dual-tube driver chip U2 as a pin, and the source of the MOS tube Q4 replaces the high-voltage floating power supply terminal of the dual-tube driver chip U2 as a pin.

5. The dual-switch flyback switching power supply according to claim 1, characterized in that: The model of the dual-tube driver chip U2 is BP6914.

6. The dual-switch flyback switching power supply according to claim 1, characterized in that: The gate of the built-in MOS tube of the single-tube driver chip U3 is led out to serve as the switch signal terminal.

7. The dual-switch flyback switching power supply according to claim 1, characterized in that: The model of the single-tube driver chip U3 is BP3187.

8. The dual-switch flyback switching power supply according to claim 1, characterized in that: It also includes a synchronous rectification module; the secondary winding of the transformer T1 is electrically connected to the synchronous rectification module; The synchronous rectification module is formed by integrating and packaging the synchronous rectification chip U4 and its peripheral circuits.

9. The dual-switch flyback switching power supply according to claim 8, characterized in that: The model of the synchronous rectification chip U4 is KP4050.

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