Switching power supply circuit, circuit board and electrical equipment

Abstract

The invention belongs to the technical field of switching power supply circuits, and particularly relates to a switching power supply circuit, a circuit board and electrical equipment, and the switching power supply circuit comprises a transformer unit, a first drive control unit and a second drive control unit. The transformer unit comprises a transformer, a first power switch module, a second power switch module, a third power switch module, a first signal transmission end and a second signal transmission end. The output end of the switching power supply realizes synchronous rectification through the second power switch module and the third power switch module, and relatively low power loss is ensured by utilizing the low internal resistance characteristics of the second power switch module and the third power switch module, so that the efficiency and the performance of the switching power supply can be greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of switching power supply circuits, and in particular relates to a switching power supply circuit, a circuit board and an electrical device. Background Art

[0002] A switching power supply is a power supply that uses modern power electronics technology to maintain a stable output voltage by controlling the on-time ratio of the switch tube.

[0003] At present, the output rectification part of the switching power supply often adopts the Schottky rectification method, which uses the unidirectional conductivity of the Schottky diode to realize the process of converting AC into DC. However, the forward voltage drop of the Schottky diode is relatively large, usually between 0.3 and 0.7V. When the current is rectified through the Schottky diode, the forward voltage drop will cause a certain power loss. For example, on the secondary side of a switching power supply with an output current of 10A, if a Schottky diode with a forward voltage drop of 0.5V is used for rectification, the power loss on the diode alone will reach 5W. This greatly reduces the efficiency and performance of the switching power supply. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a switching power supply circuit, a circuit board and an electrical device to fundamentally solve the problem that the output rectification part of the existing switching power supply adopts a Schottky rectification method, resulting in low efficiency and poor performance.

[0005] The embodiment of the present invention is implemented by providing a switching power supply circuit, including: A transformer unit, comprising a transformer, a first power switch module, a second power switch module, a third power switch module, a first signal transmission end and a second signal transmission end, wherein a primary first pin of the transformer is connected to a power supply end, a primary second pin is connected to the first power switch module, a secondary third pin is connected to the second power switch module and the first signal transmission end, a secondary fourth pin is connected to the third power switch module and the second signal transmission end, and the first power switch module is also connected to a signal input end; A first driving control unit, connected to the second power switch module; A second driving control unit, connected to the third power switch module; Among them, when the signal input end inputs a high level, the first power switch module is turned on, the first signal transmission end outputs a low level, the first drive control unit outputs a high level, the second power switch module is turned on, the second signal transmission end outputs a high level, the second drive control unit outputs a low level, the third power switch module is turned off, and the energy of the transformer flows back to the secondary third pin through the second power switch module; when the signal input end inputs a low level, the first power switch module is turned off, the first signal transmission end outputs a high level, the first drive control unit outputs a low level, the second power switch module is turned off, the second signal transmission end outputs a low level, the second drive control unit outputs a high level, the third power switch module is turned on, and the energy of the transformer flows back to the secondary fourth pin through the third power switch module.

[0006] In some embodiments, the first power switch module includes a first MOS tube, a first resistor, a second resistor and a third resistor, the gate of the first MOS tube is respectively connected to one end of the first resistor and one end of the second resistor, the source of the first MOS tube is connected to one end of the third resistor, the drain of the first MOS tube is connected to the primary second pin, the other end of the first resistor is connected to the signal input end, and the other end of the second resistor is connected to the other end of the third resistor and the input ground end.

[0007] In some embodiments, the second power switch module includes a second MOS tube, a fourth resistor and a fifth resistor, the gate of the second MOS tube is connected to one end of the fourth resistor, the source of the second MOS tube is connected to one end of the fifth resistor, the drain of the second MOS tube is connected to the secondary third pin and the first signal transmission end, and the other end of the fourth resistor is respectively connected to the other end of the fifth resistor and the first drive control unit.

[0008] In some embodiments, the third power switch module includes a third MOS tube, a sixth resistor and a seventh resistor, the gate of the third MOS tube is respectively connected to one end of the sixth resistor and one end of the seventh resistor, the source of the third MOS tube is connected to the other end of the seventh resistor, the drain of the third MOS tube is connected to the secondary fourth pin and the second signal transmission end, and the other end of the sixth resistor is connected to the second drive control unit.

[0009] In some embodiments, the transformer unit further includes a first capacitor, and the first capacitor is respectively connected to the power supply end, the primary first pin and the input ground end.

[0010] In some embodiments, the transformer unit also includes a second capacitor and a first inductor, one end of the second capacitor is respectively connected to the third power switch module and the output ground, the other end of the second capacitor is connected to one end of the first inductor, and the other end of the first inductor is respectively connected to the third power switch module.

[0011] In some embodiments, the first drive control unit includes a first drive control chip, a first transistor, a second transistor, a first diode, a second diode, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor, the base of the first transistor is connected to one end of the eighth resistor, the emitter of the first transistor is connected to the anode of the first diode, the collector of the first transistor is respectively connected to one end of the ninth resistor and the base of the second transistor, the other end of the eighth resistor is connected to the other end of the ninth resistor, the cathode of the first diode is connected to the first signal transmission end, the emitter of the second transistor is connected to the anode of the second diode, the collector of the second transistor is respectively connected to one end of the tenth resistor and one end of the eleventh resistor, the other end of the tenth resistor and the other end of the eleventh resistor are both connected to the first drive control chip, the cathode of the second diode is connected to the output ground end, and the first drive control chip is also connected to the second power switch module.

[0012] In some embodiments, the second drive control unit includes a second drive control chip, a third triode, a fourth triode, a third diode, a fourth diode, a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a fifteenth resistor, the base of the third triode is connected to one end of the twelfth resistor, the emitter of the third triode is connected to the anode of the third diode, the collector of the third triode is respectively connected to one end of the thirteenth resistor and the base of the fourth triode, the other end of the twelfth resistor is connected to the other end of the thirteenth resistor, the cathode of the third diode is connected to the second signal transmission end, the emitter of the fourth triode is connected to the anode of the fourth diode, the collector of the fourth triode is respectively connected to one end of the fourteenth resistor and one end of the fifteenth resistor, the other end of the fourteenth resistor and the other end of the fifteenth resistor are both connected to the second drive control chip, the cathode of the fourth diode is connected to the output ground end, and the second drive control chip is also connected to the third power switch module.

[0013] Another embodiment of the present invention further provides a circuit board, comprising the switching power supply circuit as described in any one of the above items.

[0014] Another embodiment of the present invention further provides an electrical device, comprising the circuit board as described above.

[0015] A switching power supply circuit, a circuit board and an electrical device provided by an embodiment of the present invention, wherein the switching power supply circuit comprises a transformer unit, a first drive control unit and a second drive control unit, wherein the transformer unit comprises a transformer, a first power switch module, a second power switch module, a third power switch module, a first signal transmission end and a second signal transmission end, wherein when a high level is input to the signal input end, the first power switch module is turned on, the first signal transmission end outputs a low level, the first drive control unit outputs a high level, the second power switch module is turned on, the second signal transmission end outputs a high level, the second drive control unit outputs a low level, the third power switch module is turned off, and the energy of the transformer flows back to the secondary third pin through the second power switch module; when a low level is input to the signal input end, the first power switch module is turned off, the first signal transmission end outputs a high level, the first drive control unit outputs a low level, the second power switch module is turned off, the second signal transmission end outputs a low level, the second drive control unit outputs a high level, the third power switch module is turned on, and the energy of the transformer flows back to the secondary fourth pin through the third power switch module. The output end of the switching power supply realizes synchronous rectification through the second power switch module and the third power switch module, and utilizes the low internal resistance characteristics of the second power switch module and the third power switch module to ensure low power loss, thereby greatly improving the efficiency and performance of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural block diagram of a switching power supply circuit provided in an embodiment of the present invention; Figure 2 is a circuit diagram of a transformer unit provided in an embodiment of the present invention; Figure 3 is a circuit diagram of a first driving control unit provided in an embodiment of the present invention; Figure 4 is a circuit diagram of a second driving control unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. 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 with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0022] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0023] refer to Figure 1 , an embodiment of the present invention provides a switching power supply circuit, comprising: The transformer unit 10 comprises a transformer T1, a first power switch module, a second power switch module, a third power switch module, a first signal transmission terminal D1 and a second signal transmission terminal D2, wherein the primary first pin of the transformer T1 is connected to the power supply terminal 40, the primary second pin is connected to the first power switch module, the secondary third pin is connected to the second power switch module and the first signal transmission terminal D1, the secondary fourth pin is connected to the third power switch module and the second signal transmission terminal D2, and the first power switch module is also connected to the signal input terminal 50; A first driving control unit 20, connected to the second power switch module; A second driving control unit 30, connected to the third power switch module; Among them, when the signal input terminal 50 inputs a high level, the first power switch module is turned on, the first signal transmission terminal D1 outputs a low level, the first drive control unit 20 outputs a high level, the second power switch module is turned on, the second signal transmission terminal D2 outputs a high level, the second drive control unit 30 outputs a low level, the third power switch module is turned off, and the energy of the transformer T1 flows back to the secondary third pin through the second power switch module; when the signal input terminal 50 inputs a low level, the first power switch module is turned off, the first signal transmission terminal D1 outputs a high level, the first drive control unit 20 outputs a low level, the second power switch module is turned off, the second signal transmission terminal D2 outputs a low level, the second drive control unit 30 outputs a high level, the third power switch module is turned on, and the energy of the transformer T1 flows back to the secondary fourth pin through the third power switch module.

[0024] Transformer T1 consists of an iron core or a magnetic core and a coil, and the coil has two or more windings, such as Figure 2As shown, the first pin 1 and the second pin 2 of the transformer T1 are connected to the power supply terminal 40, which are the primary winding, and the remaining third pin 3 and fourth pin 4 are the secondary windings. The first pin is defined as the primary first pin, the second pin is the primary second pin, the third pin is the secondary third pin, and the fourth pin is the secondary fourth pin.

[0025] The signal input terminal 50 is a PWM signal input terminal 50, which receives an externally input PWM signal.

[0026] The power supply terminal 40 is a high-voltage power supply terminal 40, which is used to connect to an external high-voltage power supply.

[0027] In this embodiment, the primary first pin of the transformer T1 is connected to the power supply terminal 40. When the signal input terminal 50 inputs a high level, the first power switch module is turned on. At this time, the power supply terminal 40 inputs current to the primary first pin and the primary second pin of the transformer T1. The voltage polarity of the primary first pin and the primary second pin is 1+ / 2-. Energy is transferred to the secondary third pin and the secondary fourth pin through the primary first pin and the primary second pin. The voltage polarity of the secondary third pin and the secondary fourth pin is 4+ / 3-. The first signal transmission terminal D1 outputs a low level, the DRV1 port of the first drive control unit 20 outputs a high level, the second power switch module is turned on, and the energy of the transformer T1 flows back to the secondary third pin through the second power switch module, forming a complete current loop, and realizing the transmission and processing of energy in the secondary winding of the transformer T1. The second signal transmission terminal D2 outputs a high level, the DRV2 port of the second drive control unit 30 outputs a low level, and the third power switch module is turned off, preventing energy from flowing back to the secondary fourth pin, thereby avoiding the formation of an undesirable current loop.

[0028] In this embodiment, when the signal input terminal 50 inputs a low level, the first power switch module is turned off, and the current path of the primary first pin and the primary second pin of the transformer T1 is cut off, the voltage polarity of the primary first pin and the primary second pin is 1- / 2+, and the energy is transferred to the secondary third pin and the secondary fourth pin through the primary first pin and the primary second pin, and the voltage polarity of the secondary third pin and the secondary fourth pin is 4- / 3+. The first signal transmission terminal D1 outputs a high level, the DRV1 port of the first drive control unit 20 outputs a low level, and the second power switch module is turned off to prevent energy from flowing back to the secondary third pin, thereby avoiding the formation of an undesirable current loop. The second signal transmission terminal D2 outputs a low level, the DRV2 port of the second drive control unit 30 outputs a high level, and the third power switch module is turned on. The energy of the transformer T1 flows back to the secondary fourth pin through the third power switch, forming a complete current loop, and realizing the transmission and processing of energy in the secondary winding of the transformer T1.

[0029] The above process is repeated continuously in countless switching cycles. When the PWM signal inputted by the signal input terminal 50 switches periodically between high level and low level, the voltage polarity of the primary winding and the secondary winding of the transformer T1 and the on and off states of the first power switch module, the second power switch module, the third power switch module, the first drive control unit 20, and the second drive control unit 30 also change periodically accordingly, realizing the storage and transmission of energy in the transformer T1 and the synchronous rectification processing at the secondary side, thereby providing a stable power output at the output end of the switching power supply to meet the power demand of the load end. In addition, the output end of the switching power supply realizes synchronous rectification through the second power switch module and the third power switch module. Compared with the Schottky rectification mode, the present invention utilizes the low internal resistance characteristics of the second power switch module and the third power switch module to ensure lower power loss, thereby greatly improving the efficiency and performance of the switching power supply.

[0030] refer to Figure 2 In some specific embodiments of the present invention, the first power switch module includes a first MOS tube Q1, a first resistor R1, a second resistor R2 and a third resistor R3, the gate of the first MOS tube Q1 is respectively connected to one end of the first resistor R1 and one end of the second resistor R2, the source of the first MOS tube Q1 is connected to one end of the third resistor R3, the drain of the first MOS tube Q1 is connected to the primary second pin, the other end of the first resistor R1 is connected to the signal input terminal 50, and the other end of the second resistor R2 is connected to the other end of the third resistor R3 and the input ground terminal PGND.

[0031] When a high level is input to the signal input terminal 50, the first MOS transistor Q1 is turned on. When a low level is input to the signal input terminal 50, the first MOS transistor Q1 is turned off. The first resistor R1 is connected between the signal input terminal 50 and the gate of the first MOS transistor Q1, and its main function is to limit the current flowing into the gate of the first MOS transistor Q1. When the level of the signal input terminal 50 changes, the first resistor R1 can prevent an instantaneous excessive current from being input into the gate of the first MOS transistor Q1, reduce the switching speed of the first MOS transistor Q1, and thus reduce the probability of damage to the first MOS transistor Q1. One end of the second resistor R2 is connected to the gate of the first MOS transistor Q1, and the other end is connected to the input ground terminal PGND, which plays the role of a pull-down resistor. When a low level is input to the signal input terminal 50 or the signal is uncertain, the second resistor R2 can ensure that the gate voltage of the first MOS transistor Q1 is pulled down, so that the first MOS transistor Q1 is reliably in the off state, and prevent the first MOS transistor Q1 from malfunctioning and being damaged by electrostatics. The third resistor R3 is connected in parallel with the second resistor R2 and connected between the source of the first MOS tube Q1 and the input ground terminal PGND, so as to limit the current flowing through the first MOS tube Q1. The parallel connection of multiple pull-down resistors can reduce the equivalent resistance value and increase the current flowing through the first MOS tube Q1.

[0032] refer to Figure 2 In some specific embodiments of the present invention, the second power switch module includes a second MOS tube Q2, a fourth resistor R4 and a fifth resistor R5, the gate of the second MOS tube Q2 is connected to one end of the fourth resistor R4, the source of the second MOS tube Q2 is connected to one end of the fifth resistor R5, the drain of the second MOS tube Q2 is connected to the secondary third pin and the first signal transmission end D1, and the other end of the fourth resistor R4 is respectively connected to the other end of the fifth resistor R5 and the first driving control unit 20.

[0033] When the DRV1 port of the first drive control unit 20 outputs a high level, the second MOS tube Q2 is turned on, and the energy of the transformer T1 flows from the source of the second MOS tube Q2 through the drain and back to the secondary third pin. When the DRV1 port of the first drive control unit 20 outputs a low level, the second MOS tube Q2 is turned off. The fourth resistor R4 is connected between the DRV1 port of the first drive control unit 20 and the gate of the second MOS tube Q2. The main function is to limit the current flowing into the gate of the second MOS tube Q2. When the level of the DRV1 port changes, the fourth resistor R4 can prevent the instantaneous excessive current from being input into the gate of the second MOS tube Q2, reduce the switching speed of the second MOS tube Q2, and thus reduce the probability of damage to the second MOS tube Q2. The fifth resistor R5 is connected between the source of the second MOS tube Q2 and the DRV1 port of the first drive control unit 20. The main function is to prevent the second MOS tube Q2 from malfunctioning and electrostatic damage, and further improve the protection of the second MOS tube Q2.

[0034] refer to Figure 2 In some specific embodiments of the present invention, the third power switch module includes a third MOS tube Q3, a sixth resistor R6 and a seventh resistor R7, the gate of the third MOS tube Q3 is respectively connected to one end of the sixth resistor R6 and one end of the seventh resistor R7, the source of the third MOS tube Q3 is connected to the other end of the seventh resistor R7, the drain of the third MOS tube Q3 is connected to the secondary fourth pin and the second signal transmission end D2, and the other end of the sixth resistor R6 is connected to the second driving control unit 30.

[0035] When the DRV2 port of the second drive control unit 30 outputs a high level, the third MOS tube Q3 is turned on, and the energy of the transformer T1 flows from the source of the third MOS tube Q3 through the drain and back to the secondary fourth pin. When the DRV2 port of the second drive control unit 30 outputs a low level, the third MOS tube Q3 is turned off. The sixth resistor R6 is connected between the DRV2 port of the second drive control unit 30 and the gate of the third MOS tube Q3, and its main function is to limit the current flowing into the gate of the third MOS tube Q3. When the level of the DRV2 port changes, the sixth resistor R6 can prevent the instantaneous excessive current from being input into the gate of the third MOS tube Q3, reduce the switching speed of the third MOS tube Q3, and thus reduce the probability of damage to the third MOS tube Q3. The seventh resistor R7 is connected between the gate and the source of the third MOS tube Q3, and its main function is to prevent the third MOS tube Q3 from malfunctioning and being damaged by electrostatics, and further improve the protection of the third MOS tube Q3.

[0036] refer to Figure 2 In some specific embodiments of the present invention, the transformer unit 10 further includes a first capacitor C1, which is connected to the power supply terminal 40, the primary first pin and the input ground terminal PGND respectively. The first capacitor C1 mainly plays a filtering role. When the power supply terminal 40 inputs power, the first capacitor C1 removes the clutter in the power supply to make the input voltage more stable.

[0037] refer to Figure 2 In some specific embodiments of the present invention, the transformer unit 10 further includes a second capacitor C2 and a first inductor L1, one end of the second capacitor C2 is respectively connected to the third power switch module and the output ground GND, the other end of the second capacitor C2 is connected to one end of the first inductor L1, and the other end of the first inductor L1 is respectively connected to the third power switch module. The second capacitor C2 and the first inductor L1 form an LC filter circuit, which can filter out high-frequency noise and interference and make the output voltage smoother. For example, at the output end of the switching power supply of this embodiment, the LC filter circuit composed of the second capacitor C2 and the first inductor L1 can effectively reduce the ripple caused by the switching frequency.

[0038] refer to Figure 3In some specific embodiments of the present invention, the first driving control unit 20 includes a first driving control chip U1, a first transistor Q4, a second transistor Q5, a first diode D1, a second diode D2, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11, the base of the first transistor Q4 is connected to one end of the eighth resistor R8, the emitter of the first transistor Q4 is connected to the anode of the first diode D1, the collector of the first transistor Q4 is connected to one end of the ninth resistor R9 and the base of the second transistor Q5, and the eighth resistor R8 is connected to the emitter of the first transistor Q4. The other end of R8 is connected to the other end of the ninth resistor R9, the cathode of the first diode D1 is connected to the first signal transmission end D1, the emitter of the second transistor Q5 is connected to the anode of the second diode D2, the collector of the second transistor Q5 is respectively connected to one end of the tenth resistor R10 and one end of the eleventh resistor R11, the other end of the tenth resistor R10 and the other end of the eleventh resistor R11 are both connected to the first drive control chip U1, the cathode of the second diode D2 is connected to the output ground end GND, and the first drive control chip U1 is also connected to the second power switch module.

[0039] When the first signal transmission terminal D1 outputs a low level, the first transistor Q4 is turned on, the second transistor Q5 is turned off, the eleventh resistor R11 and the IN+ pin and IN- pin of the first drive control chip U1 are high levels, and the DRV1 port of the first drive control chip U1 outputs a high level, so that the second power switch module is turned on. When the first signal transmission terminal D1 outputs a high level, the first transistor Q4 is turned off, the second transistor Q5 is turned on, the eleventh resistor R11 and the IN+ pin and IN- pin of the first drive control chip U1 are low levels, and the DRV1 port of the first drive control chip U1 outputs a low level, so that the second power switch module is turned off. The first diode D1 protects the first transistor Q4 from reverse electromotive force damage when it is turned off, and plays a protective role. The second diode D2 protects the second transistor Q5 from reverse electromotive force damage when it is turned off, and plays a protective role. The eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 play a current limiting role.

[0040] refer to Figure 4In some specific embodiments of the present invention, the second driving control unit 30 includes a second driving control chip U2, a third transistor Q6, a fourth transistor Q7, a third diode D3, a fourth diode D4, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a fifteenth resistor R15, the base of the third transistor Q6 is connected to one end of the twelfth resistor R12, the emitter of the third transistor Q6 is connected to the anode of the third diode D3, the collector of the third transistor Q6 is respectively connected to one end of the thirteenth resistor R13 and the base of the fourth transistor Q7, the twelfth resistor R14 is connected to the emitter of the third transistor Q6, and the collector of the third transistor Q6 is respectively connected to one end of the thirteenth resistor R13 and the base of the fourth transistor Q7. The other end of the resistor R12 is connected to the other end of the thirteenth resistor R13, the cathode of the third diode D3 is connected to the second signal transmission end D2, the emitter of the fourth transistor Q7 is connected to the anode of the fourth diode D4, the collector of the fourth transistor Q7 is respectively connected to one end of the fourteenth resistor R14 and one end of the fifteenth resistor R15, the other end of the fourteenth resistor R14 and the other end of the fifteenth resistor R15 are both connected to the second drive control chip U2, the cathode of the fourth diode D4 is connected to the output ground end GND, and the second drive control chip U2 is also connected to the third power switch module.

[0041] When the second signal transmission terminal D2 outputs a low level, the third transistor Q6 is turned on, the fourth transistor Q7 is turned off, the fifteenth resistor R15 and the IN+ pin and IN- pin of the second drive control chip U2 are high level, and the DRV2 port of the second drive control chip U2 outputs a high level, so that the third power switch module is turned on. When the second signal transmission terminal D2 outputs a high level, the third transistor Q6 is turned off, the fourth transistor Q7 is turned on, the fifteenth resistor R15 and the IN+ pin and IN- pin of the second drive control chip U2 are low level, and the DRV2 port of the second drive control chip U2 outputs a low level, so that the third power switch module is turned off. The third diode D3 protects the third transistor Q6 from reverse electromotive force damage when it is turned off, and plays a protective role. The fourth diode D4 protects the fourth transistor Q7 from reverse electromotive force damage when it is turned off, and plays a protective role. The twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 play a current limiting role.

[0042] An embodiment of the present invention further provides a circuit board, comprising the switching power supply circuit as described in any one of the above embodiments. The switching power supply circuit includes a transformer unit 10, a first driving control unit 20 and a second driving control unit 30. The transformer unit 10 includes a transformer T1, a first power switch module, a second power switch module, a third power switch module, a first signal transmission terminal D1 and a second signal transmission terminal D2. When a high level is input to the signal input terminal 50, the first power switch module is turned on, the first signal transmission terminal D1 outputs a low level, the first driving control unit 20 outputs a high level, the second power switch module is turned on, the second signal transmission terminal D2 outputs a high level, the second driving control unit 30 outputs a low level, the third power switch module is turned off, and the energy of the transformer T1 flows back to the secondary third pin through the second power switch module; when a low level is input to the signal input terminal 50, the first power switch module is turned off, the first signal transmission terminal D1 outputs a high level, the first driving control unit 20 outputs a low level, the second power switch module is turned off, the second signal transmission terminal D2 outputs a low level, the second driving control unit 30 outputs a high level, the third power switch module is turned on, and the energy of the transformer T1 flows back to the secondary fourth pin through the third power switch module. The output end of the switching power supply realizes synchronous rectification through the second power switch module and the third power switch module. Compared with the Schottky rectification method, the present invention utilizes the low internal resistance characteristics of the second power switch module and the third power switch module to ensure lower power loss, thereby greatly improving the efficiency and performance of the switching power supply.

[0043] An embodiment of the present invention further provides an electrical device, comprising the circuit board as described above. The circuit board comprises the switching power supply circuit as described in any one of the above embodiments. The switching power supply circuit includes a transformer unit 10, a first driving control unit 20 and a second driving control unit 30. The transformer unit 10 includes a transformer T1, a first power switch module, a second power switch module, a third power switch module, a first signal transmission terminal D1 and a second signal transmission terminal D2. When a high level is input to the signal input terminal 50, the first power switch module is turned on, the first signal transmission terminal D1 outputs a low level, the first driving control unit 20 outputs a high level, the second power switch module is turned on, the second signal transmission terminal D2 outputs a high level, the second driving control unit 30 outputs a low level, the third power switch module is turned off, and the energy of the transformer T1 flows back to the secondary third pin through the second power switch module; when a low level is input to the signal input terminal 50, the first power switch module is turned off, the first signal transmission terminal D1 outputs a high level, the first driving control unit 20 outputs a low level, the second power switch module is turned off, the second signal transmission terminal D2 outputs a low level, the second driving control unit 30 outputs a high level, the third power switch module is turned on, and the energy of the transformer T1 flows back to the secondary fourth pin through the third power switch module. The output end of the switching power supply realizes synchronous rectification through the second power switch module and the third power switch module. Compared with the Schottky rectification method, the present invention utilizes the low internal resistance characteristics of the second power switch module and the third power switch module to ensure lower power loss, thereby greatly improving the efficiency and performance of the switching power supply.

[0044] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A switching power supply circuit, characterized in that: include: A transformer unit, comprising a transformer, a first power switch module, a second power switch module, a third power switch module, a first signal transmission end and a second signal transmission end, wherein a primary first pin of the transformer is connected to a power supply end, a primary second pin is connected to the first power switch module, a secondary third pin is connected to the second power switch module and the first signal transmission end, a secondary fourth pin is connected to the third power switch module and the second signal transmission end, and the first power switch module is also connected to a signal input end; A first driving control unit, connected to the second power switch module; A second driving control unit, connected to the third power switch module; Among them, when the signal input end inputs a high level, the first power switch module is turned on, the first signal transmission end outputs a low level, the first drive control unit outputs a high level, the second power switch module is turned on, the second signal transmission end outputs a high level, the second drive control unit outputs a low level, the third power switch module is turned off, and the energy of the transformer flows back to the secondary third pin through the second power switch module; when the signal input end inputs a low level, the first power switch module is turned off, the first signal transmission end outputs a high level, the first drive control unit outputs a low level, the second power switch module is turned off, the second signal transmission end outputs a low level, the second drive control unit outputs a high level, the third power switch module is turned on, and the energy of the transformer flows back to the secondary fourth pin through the third power switch module.

2. The switching power supply circuit according to claim 1, characterized in that: The first power switch module includes a first MOS tube, a first resistor, a second resistor and a third resistor, the gate of the first MOS tube is respectively connected to one end of the first resistor and one end of the second resistor, the source of the first MOS tube is connected to one end of the third resistor, the drain of the first MOS tube is connected to the primary second pin, the other end of the first resistor is connected to the signal input end, and the other end of the second resistor is connected to the other end of the third resistor and the input ground end.

3. The switching power supply circuit according to claim 1, characterized in that: The second power switch module includes a second MOS tube, a fourth resistor and a fifth resistor, the gate of the second MOS tube is connected to one end of the fourth resistor, the source of the second MOS tube is connected to one end of the fifth resistor, the drain of the second MOS tube is connected to the secondary third pin and the first signal transmission end, and the other end of the fourth resistor is respectively connected to the other end of the fifth resistor and the first drive control unit.

4. The switching power supply circuit according to claim 1, characterized in that: The third power switch module includes a third MOS tube, a sixth resistor and a seventh resistor, the gate of the third MOS tube is respectively connected to one end of the sixth resistor and one end of the seventh resistor, the source of the third MOS tube is connected to the other end of the seventh resistor, the drain of the third MOS tube is connected to the secondary fourth pin and the second signal transmission end, and the other end of the sixth resistor is connected to the second drive control unit.

5. The switching power supply circuit according to claim 1, characterized in that: The transformer unit further includes a first capacitor, which is respectively connected to the power supply end, the primary first pin and the input ground end.

6. The switching power supply circuit according to claim 1, characterized in that: The transformer unit also includes a second capacitor and a first inductor, one end of the second capacitor is respectively connected to the third power switch module and the output ground, the other end of the second capacitor is connected to one end of the first inductor, and the other end of the first inductor is respectively connected to the third power switch module.

7. The switching power supply circuit according to any one of claims 1 to 6, characterized in that: The first driving control unit includes a first driving control chip, a first triode, a second triode, a first diode, a second diode, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor. The base of the first triode is connected to one end of the eighth resistor, the emitter of the first triode is connected to the anode of the first diode, the collector of the first triode is respectively connected to one end of the ninth resistor and the base of the second triode, the other end of the eighth resistor is connected to the other end of the ninth resistor, the cathode of the first diode is connected to the first signal transmission end, the emitter of the second triode is connected to the anode of the second diode, the collector of the second triode is respectively connected to one end of the tenth resistor and one end of the eleventh resistor, the other end of the tenth resistor and the other end of the eleventh resistor are both connected to the first driving control chip, the cathode of the second diode is connected to the output ground end, and the first driving control chip is also connected to the second power switch module.

8. The switching power supply circuit according to any one of claims 1 to 6, characterized in that: The second drive control unit includes a second drive control chip, a third triode, a fourth triode, a third diode, a fourth diode, a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a fifteenth resistor. The base of the third triode is connected to one end of the twelfth resistor, the emitter of the third triode is connected to the anode of the third diode, the collector of the third triode is respectively connected to one end of the thirteenth resistor and the base of the fourth triode, the other end of the twelfth resistor is connected to the other end of the thirteenth resistor, the cathode of the third diode is connected to the second signal transmission end, the emitter of the fourth triode is connected to the anode of the fourth diode, the collector of the fourth triode is respectively connected to one end of the fourteenth resistor and one end of the fifteenth resistor, the other end of the fourteenth resistor and the other end of the fifteenth resistor are both connected to the second drive control chip, the cathode of the fourth diode is connected to the output ground end, and the second drive control chip is also connected to the third power switch module.

9. A circuit board, characterized in that: The invention comprises a switching power supply circuit as claimed in any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising the circuit board as claimed in claim 9.

Images