A high-precision switching power supply

Abstract

The application relates to the technical field of switching power supplies, in particular to a high-precision switching power supply which comprises a PFC module and a transformer T4, and further comprises an LLC control module, a mutual inductor T1 and a switching tube module; the PFC module and the switching tube module are electrically connected, the PFC module outputs a VBUS voltage to the switching tube module, the switching tube module and a first winding of the primary side of the transformer T4 are electrically connected; the driving end of the LLC control module and the input end of the mutual inductor T1 are electrically connected, the mutual inductor end of the mutual inductor T1 and the switching tube module are electrically connected; the LLC control module drives the upper and lower tubes of the switching tube module to be turned on or turned off through the mutual inductor T1; the current sampling end of the LLC control module and the switching tube module are electrically connected, and the current sampling end is used for enabling the LLC control module to drive the upper and lower tube state of the switching tube module to be turned over; the problems that the existing high-precision switching power supply has a large maintenance current, high power consumption and easy precision decline are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a high-precision switching power supply. BACKGROUND

[0002] The high-precision switching power supply is usually extremely sensitive to temperature, when the overall power consumption of the switching power supply is large, it will cause the overall temperature rise to be large, resulting in the parameter drift of integrated devices, so as to reduce the precision. Especially the LLC module of the switching power supply, the mains passes through the amplitude limiting module to the PFC module, the PFC module outputs the VBUS voltage to the LLC module, and the LLC module (for example, composed of two SY59515 chips and its peripheral circuit) drives (direct drive type) the built-in MOS tube to be turned on or closed by itself, and a large working current is required during work. The working current is usually maintained at more than mA level, the power consumption is difficult to reduce, and the performance of the high-precision switching power supply is seriously affected. SUMMARY

[0003] In view of the above defects, the purpose of the present application is to provide a high-precision switching power supply, which solves the problem of large holding current, high power consumption and easy precision reduction of the existing high-precision switching power supply.

[0004] In order to achieve this purpose, the technical scheme adopted by the present application is as follows:

[0005] A high-precision switching power supply, comprising a PFC module and a transformer T4, further comprising an LLC control module, a mutual inductor T1 and a switch tube module; the PFC module and the switch tube module are electrically connected, the PFC module outputs a VBUS voltage to the switch tube module, and the switch tube module and the primary side first winding of the transformer T4 are electrically connected;

[0006] The driving end of the LLC control module and the input end of the mutual inductor T1 are electrically connected, and the mutual inductive end of the mutual inductor T1 and the switch tube module are electrically connected; the switch tube module comprises upper and lower tubes, and the upper and lower tubes refer to two switch tubes in the switch tube module; the LLC control module drives the upper and lower tubes of the switch tube module to be turned on or turned off through the mutual inductor T1;

[0007] The current sampling end of the LLC control module and the switch tube module are electrically connected, for enabling the LLC control module to drive the upper and lower tubes of the switch tube module to flip.

[0008] Further, the switch tube module comprises a diode D4, a diode D5, a capacitor C9, a capacitor CB3, a sampling resistor RCS1, a sampling resistor RCS2, a sampling resistor RCS3 and a triode chip Q1; the triode chip Q1 comprises upper and lower triodes, which are two triodes in the triode chip Q1; the upper and lower triodes of the triode chip Q1 are used as the upper and lower tubes of the switch tube module respectively;

[0009] The collector of the upper triode of the triode chip Q1 and the cathode of the diode D4 are connected to the VBUS voltage, the emitter of the upper triode of the triode chip Q1 and the collector of the lower triode of the triode chip Q1 are electrically connected, the base of the upper triode of the triode chip Q1, the base of the lower triode of the triode chip Q1, the emitter of the upper triode of the triode chip Q1 and the anode of the diode D4 are electrically connected to the mutual inductance end of the transformer T1;

[0010] The same name end of the primary side first winding of the transformer T4, the anode of the diode D4 and one end of the capacitor C9 are electrically connected to the cathode of the diode D5, the other end of the capacitor C9, the anode of the diode D5, one end of the sampling resistor RCS1 and one end of the sampling resistor RCS2 are connected to the GND ground end, the different name end of the primary side first winding of the transformer T4 and one end of the capacitor CB3 are electrically connected, the other end of the capacitor CB3, the other end of the sampling resistor RCS1 and the other end of the sampling resistor RCS2 are electrically connected to one end of the sampling resistor RCS3, the other end of the sampling resistor RCS3 and the current sampling end of the LLC control module are electrically connected.

[0011] Further, it further comprises a resistor R3 and a resistor R4; the secondary side first winding of the transformer T1 is used as the input end of the transformer T1; the different name end of the secondary side second winding of the transformer T1, the primary side first winding and the second winding of the transformer T1 are used as the mutual inductance end of the transformer T1;

[0012] The same name end of the secondary side second winding of the transformer T1 is connected to the GND ground end, the different name end of the secondary side second winding of the transformer T1 is electrically connected to the base of the lower triode of the triode chip Q1 through the resistor R4, the same name end of the primary side first winding of the transformer T1 is electrically connected to the base of the upper triode of the triode chip Q1 through the resistor R3, the different name end of the primary side first winding of the transformer T1 and the same name end of the primary side second winding of the transformer T1 are electrically connected to the emitter of the upper triode of the triode chip Q1, and the different name end of the primary side second winding of the transformer T1 and the anode of the diode D4 are electrically connected.

[0013] Further, the turns ratio of the primary side second winding W4, the primary side first winding W3, the secondary side first winding W2 and the secondary side second winding W1 of the transformer T1 is:

[0014] W1:W2:W3:W4=5:15:5:1.

[0015] Further, the transformer T1 is a PCB transformer, and the PCB transformer is divided into six layers, wherein:

[0016] The first layer of the PCB transformer prints the coil of the secondary side first winding W2 of the transformer T1, and the number of turns is five turns.

[0017] The second layer of the PCB transformer prints the coil of the secondary side second winding W1 of the transformer T1, and the number of turns is five turns.

[0018] The third layer of the PCB transformer prints the coil of the secondary side first winding W2 of the transformer T1, and the number of turns is five turns.

[0019] The fourth layer of the PCB transformer prints the coil of the primary side first winding W3 of the transformer T1, and the number of turns is five turns.

[0020] The fifth layer of the PCB transformer prints the coil of the secondary side first winding W2 of the transformer T1, and the number of turns is five turns.

[0021] The sixth layer of the PCB transformer prints the coil of the primary side second winding W4 of the transformer T1, and the number of turns is one turn.

[0022] The first layer, the third layer and the fifth layer of the PCB transformer are connected in series.

[0023] Further, it further comprises a transformer T3, a signal processing module and an output module electrically connected to the secondary side of the transformer T4; the first winding of the transformer T3 is connected in series to the positive electrode of the output module, one end of the second winding of the transformer T3 is connected to the GND ground end, and the other end of the second winding of the transformer T3 is electrically connected to the signal feedback end of the LLC control module through the signal processing module.

[0024] Further, the turns ratio of the first winding and the second winding of the transformer T3 is 1:100, and the first winding of the transformer T3 is only wound with one coil.

[0025] Further, the LLC control module comprises a diode D18, a diode D22, a resistor R16, a resistor R18, a capacitor C16, a capacitor C10, a capacitor C12 and an LLC control chip U2; a first output end and a second output end of the LLC control chip U2 are used as driving ends of the LLC control module, a current sampling end of the LLC control chip U2 is used as a current sampling end of the LLC control module, and a signal feedback end of the LLC control chip U2 is used as a signal feedback end of the LLC control module;

[0026] An anode of the diode D18 and a same-named end of a primary side second winding of the transformer T4 are electrically connected, an opposite-named end of the primary side second winding of the transformer T4 is connected to a GND ground end, a cathode of the diode D18 and one end of the resistor R18 are electrically connected, the other end of the resistor R18, one end of the resistor R16 and one end of the capacitor C12 are electrically connected to a voltage feedback end of the LLC control chip U2, and the other end of the resistor R16 and the other end of the capacitor C12 are both connected to the GND ground end;

[0027] An anode of the diode D22 and the anode of the diode D18 are electrically connected, one end of the capacitor C16 and the cathode of the diode D18 are electrically connected, a cathode of the diode D22 and one end of the capacitor C10 are electrically connected, the other end of the capacitor C10 and the other end of the capacitor C16 are both connected to the GND ground end, and the cathode of the diode D22 and the common connection point of one end of the capacitor C10 are used for externally connecting a protection signal.

[0028] Further, the signal processing module comprises a diode D21, a capacitor C14, a resistor R60, a resistor R61, a resistor R57 and a capacitor C13; the other end of the second winding of the transformer T3 and the anode of the diode D21 are electrically connected, the cathode of the diode D21, one end of the capacitor C14, one end of the resistor R60, one end of the resistor R61 and one end of the resistor R57 are electrically connected, the other end of the resistor R57 and one end of the capacitor C13 are electrically connected, the other end of the capacitor C14, the other end of the resistor R60, the other end of the resistor R61 and the other end of the capacitor C13 are all connected to the ground, and the other end of the resistor R57 is also electrically connected to the signal feedback end of the LLC control module.

[0029] The technical scheme provided by the application can have the following beneficial effects: the LLC part in the switching power supply is changed to an LLC control module, which drives the upper and lower tubes of the switching tube module to be turned on or turned off through the mutual inductor T1, instead of the original LLC main power module, so that the LLC control module only needs to provide a pulse current (within 8 mA) to the mutual inductor T1 to turn on the switching tube of the switching tube module at the starting moment, and the mutual inductor T1 maintains the switching tube to be turned on through the inductive loop current after the switching tube is turned on, the working current of the LLC control module is maintained at 140 mu A or even 50 mu A, and no additional current needs to be provided to drive the switching tube to work; when the LLC control module detects that the switching tube turning-on timing ends through the current sampling end (CS), the driving signals (TX1 and TX2) output by the LLC control module to the mutual inductor T1 are periodically reversed, the LLC control module drives the corresponding windings of the mutual inductor T1 to be short-circuited to the ground, the mutual inductor T1 discharges energy, and the switching tube is turned off (that is, the upper and lower tube states are reversed). It can be seen that the working current is reduced from the mA level to the mu A level, the power consumption is greatly reduced, and the precision of the high-precision switching power supply is avoided to be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a circuit schematic diagram of a high-precision switching power supply according to one embodiment of the application.

[0031] Figure 2 is a winding schematic diagram of the mutual inductor T1 as shown in Figure 1 .

[0032] Figure 3 is a PCB structure schematic diagram of the mutual inductor T1 as shown in Figure 1 .

[0033] Figure 4 is a circuit diagram of the LLC control module and the signal processing module as shown in Figure 1 .

[0034] Figure 5 is an internal circuit diagram of the triode chip Q1 according to one embodiment as shown in Figure 1 .

[0035] PFC module 1, LLC control module 2, mutual inductor T1, switching tube module 3, transformer T4, diode D4, diode D5, capacitor C9, capacitor CB3, sampling resistor RCS1, sampling resistor RCS2, sampling resistor RCS3, triode chip Q1, resistor R3, resistor R4, mutual inductor T3, signal processing module 5, output module 4, diode D18, diode D22, resistor R16, resistor R18, capacitor C16, capacitor C10, capacitor C12, LLC control chip U2, diode D21, capacitor C14, resistor R60, resistor R61, resistor R57, capacitor C13. DETAILED DESCRIPTION

[0036] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components or components having the same or similar functions are denoted by the same or similar reference numerals throughout the drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0037] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features, which are used to distinguish the described features, and have no order or importance.

[0038] In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0039] In the description of the embodiments of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0040] The embodiments of the present application are described below in conjunction with Figures 1 to 4 , a high-precision switching power supply.

[0041] A high-precision switching power supply comprises a PFC module 1 and a transformer T4, further comprising an LLC control module 2, a mutual inductor T1 and a switch tube module 3; the PFC module 1 and the switch tube module 3 are electrically connected, the PFC module 1 outputs a VBUS voltage to the switch tube module 3, and the switch tube module 3 and the primary side first winding of the transformer T4 are electrically connected;

[0042] The driving end of the LLC control module 2 is electrically connected with the input end of the mutual inductor T1, and the mutual inductor T1 is electrically connected with the switch tube module 3; the switch tube module 3 comprises upper and lower tubes, and the upper and lower tubes refer to two switch tubes in the switch tube module 3; the LLC control module 2 drives the upper and lower tubes of the switch tube module 3 to be turned on or turned off through the mutual inductor T1.

[0043] The current sampling end of the LLC control module 2 is electrically connected with the switch tube module 3, so as to enable the LLC control module 2 to drive the upper and lower tubes of the switch tube module 3 to be turned over.

[0044] As shown in the preferred embodiment of the high-precision switching power supply, Figure 1 the LLC part in the switching power supply is changed to the LLC control module 2 driving the upper and lower tubes of the switch tube module 3 to be turned on or turned off through the mutual inductor T1, instead of the original LLC main power module, so that the LLC control module 2 only needs to provide a pulse current (within 8 mA) to the mutual inductor T1 to turn on the switch tube of the switch tube module 3 at the starting moment, and after the switch tube is turned on, the mutual inductor T1 maintains the switch tube to be turned on through the inductive circuit current, the working current of the LLC control module 2 is maintained at 140 μA, even 50 μA, and no additional current is needed to drive the switch tube to work; when the LLC control module 2 detects that the switch tube turning-on timing is over through the current sampling end (CS), the LLC control module 2 periodically turns over the driving signals (TX1, TX2) output to the mutual inductor T1, the LLC control module 2 drives the corresponding windings of the mutual inductor T1 to be short-circuited to the ground, the mutual inductor T1 discharges energy, and the switch tube is turned off (i.e., the upper and lower tube state is turned over). It can be seen that the working current is reduced from the mA level to the μA level, the power consumption is greatly reduced, and the precision of the high-precision switching power supply is avoided to be reduced.

[0045] It should be noted that there are many internal circuit structures of the switch tube module 3, and the core is that two switch tubes are integrated, and reference can be made to Figure 5 , wherein the upper tube is the upper tube, and the lower tube is the lower tube, and the peripheral circuit of the switch tube module 3 is built around the driving of the two switch tubes, and there are many implementation manners, which are not limited here.

[0046] Further, the switch tube module 3 comprises diode D4, diode D5, capacitor C9, capacitor CB3, sampling resistor RCS1, sampling resistor RCS2, sampling resistor RCS3 and triode chip Q1; the triode chip Q1 comprises upper and lower triodes, and the upper and lower triodes refer to two triodes in the triode chip Q1; the upper and lower triodes of the triode chip Q1 are used as the upper and lower tubes of the switch tube module 3 respectively;

[0047] The collector of the upper triode of the triode chip Q1 and the cathode of the diode D4 are connected with the VBUS voltage, the emitter of the upper triode of the triode chip Q1 and the collector of the lower triode of the triode chip Q1 are electrically connected, the base of the upper triode of the triode chip Q1, the base of the lower triode of the triode chip Q1, the emitter of the upper triode of the triode chip Q1 and the anode of the diode D4 are electrically connected with the mutual inductance end of the transformer T1;

[0048] The same name end of the primary side first winding of the transformer T4, the anode of the diode D4 and one end of the capacitor C9 are electrically connected with the cathode of the diode D5, the other end of the capacitor C9, the anode of the diode D5, one end of the sampling resistor RCS1 and one end of the sampling resistor RCS2 are connected with the GND ground end, the different name end of the primary side first winding of the transformer T4 and one end of the capacitor CB3 are electrically connected, the other end of the capacitor CB3, the other end of the sampling resistor RCS1 and the other end of the sampling resistor RCS2 are electrically connected with one end of the sampling resistor RCS3, the other end of the sampling resistor RCS3 and the current sampling end of the LLC control module 2 are electrically connected.

[0049] In the embodiment, the triode is a current-driven switch tube, which is more suitable for the induced current of the transformer T1; therefore, the switch tube module 3 is built with a peripheral circuit taking the triode chip Q1 as the core and is electrically connected between the PFC module 1 and the transformer T4, wherein the sampling resistor RCS1, the sampling resistor RCS2 and the sampling resistor RCS3 constitute a sampling circuit to feed back the working state of the upper and lower tubes in the triode chip Q1 to the LLC control module 2.

[0050] It should be noted that the triode chip Q1 in the figure is taken as an example of the RED3032 model, which is described in detail in Figure 5 The upper triode is on the top and the lower triode is on the bottom, and the 6-pin and 5-pin in the chip specification book are marked as E1, which actually means that the emitter of the upper triode and the collector of the lower triode are connected together.

[0051] Further, the resistor R3 and the resistor R4 are further included, the secondary side first winding of the transformer T1 is used as the input end of the transformer T1, the different name end of the secondary side second winding of the transformer T1, the primary side first winding and the second winding of the transformer T1 are used as the mutual inductance end of the transformer T1;

[0052] The same name end of the secondary side second winding of the mutual inductor T1 is connected to the GND ground end, the different name end of the secondary side second winding of the mutual inductor T1 is electrically connected to the base electrode of the lower triode of the triode chip Q1 through the resistance R4, the same name end of the primary side first winding of the mutual inductor T1 is electrically connected to the base electrode of the upper triode of the triode chip Q1 through the resistance R3, the different name end of the primary side first winding of the mutual inductor T1 and the same name end of the primary side second winding are electrically connected to the emitter electrode of the upper triode of the triode chip Q1, and the different name end of the primary side second winding of the mutual inductor T1 and the anode electrode of the diode D4 are electrically connected.

[0053] In the embodiment, the electrical connection mode of the mutual inductor T1 and the triode chip Q1 is as shown in the above, and the control timing sequence is as shown in the following: Figure 1 and 2 It can be known that the control timing sequence is as follows: (in the mutual inductor T1, the primary side second winding is W1, the primary side first winding is W2, the secondary side first winding is W3, and the secondary side second winding is W4, and the following is for convenience of description, and the numbers are used instead)

[0054] The control timing sequence one: at the start, the LLC control module 2 provides a pulse current through the TX1 and TX2 pins, the W1 in-phase induction current makes the upper triode conductive, at this time, the W3 is in anti-phase, so the lower triode is in the off state; after the upper triode is turned on, the main loop current flows through the W4, the W1 in-phase induction current maintains the upper triode conductive until the W4 current reaches the threshold value of the LLC control module 2 (i.e. the threshold value of the chip), the LLC control module 2 pulls down the TX1 and TX2 pins to the ground, discharges the energy of the mutual inductor T1, and turns off the upper triode.

[0055] The control timing sequence two: in the next half cycle, the LLC control module 2 releases the TX1 and TX2 pins (outputs the driving signal of the period flip), the resonant current reversely flows through the W4, at this time, the W3 in-phase induction current makes the lower triode conductive, and maintains the lower triode conductive until the W4 current reaches the threshold value of the LLC control module 2 (i.e. the threshold value of the chip), the LLC control module 2 pulls down the TX1 and TX2 pins to the ground, discharges the energy of the mutual inductor T1, and turns off the lower triode.

[0056] It should be noted that for the mutual inductor T1 and the switch tube module 3, the LLC control module 2 only provides a pulse current at the start, and only releases or turns off (pulls down) the TX1 and TX2 pins at other times, the working current is small, and the power consumption is low.

[0057] Further, the turns ratio of the primary side second winding W4, the primary side first winding W3, the secondary side first winding W2 and the secondary side second winding W1 of the mutual inductor T1 is:

[0058] W1: W2: W3: W4 = 5: 15: 5: 1.

[0059] In this embodiment, the W2 of the mutual inductor T1 is connected to the control pins TX1 and TX2 of the LLC control module 2, the W1 and W3 are connected to the upper and lower tubes of the switch tube module 3 respectively, and the W4 is connected in series on the resonant half-bridge main circuit, and the ratio of W1:W2:W3:W4 is 5:15:5:1. The current of the ratio is designed and calculated, and the current of 1 / 5 of the main circuit is obtained through induction by W1 and W3. The current size is related to the working state of the triode. If the current is too small, the triode cannot work in the saturation state, and if the current is too large, it will affect the triode turn-off and loss.

[0060] Further, the mutual inductor T1 is a PCB mutual inductor, and the PCB mutual inductor is divided into six layers, wherein:

[0061] The first layer of the PCB mutual inductor prints the coil of the first winding W2 on the secondary side of the mutual inductor T1, and the number of turns is five turns.

[0062] The second layer of the PCB mutual inductor prints the coil of the second winding W1 on the secondary side of the mutual inductor T1, and the number of turns is five turns.

[0063] The third layer of the PCB mutual inductor prints the coil of the first winding W2 on the secondary side of the mutual inductor T1, and the number of turns is five turns.

[0064] The fourth layer of the PCB mutual inductor prints the coil of the first winding W3 on the primary side of the mutual inductor T1, and the number of turns is five turns.

[0065] The fifth layer of the PCB mutual inductor prints the coil of the first winding W2 on the secondary side of the mutual inductor T1, and the number of turns is five turns.

[0066] The sixth layer of the PCB mutual inductor prints the coil of the second winding W4 on the primary side of the mutual inductor T1, and the number of turns is one turn.

[0067] The first layer, the third layer and the fifth layer of the PCB mutual inductor are connected in series.

[0068] In this embodiment, the mutual inductor T1 preferably adopts a PCB mutual inductor, which uses the PCB wiring method to make the winding, has smaller size, occupies less space, and basically has no leakage inductance effect (the traditional method is to use a magnetic ring or a skeleton winding method, which is easy to be affected by process and coupling difference, resulting in large leakage inductance and affecting the switch tube turn-off), and can realize high-precision control of switch tube conduction or turn-off.

[0069] Based on W1:W2:W3:W4=5:15:5:1 in the mutual inductor T1, when printing the PCB mutual inductor, as shown in the figure, Figure 3 preferably, a maximum of five turns is one layer, and W2 is arranged in layers with a gap, which is more conducive to the better coupling of W2 with W1 and W3 respectively, and improves the inductive current accuracy. It should be noted that, Figure 3The middle PP layer and the core layer belong to the existing process of the PCB plate and are only used as an illustration.

[0070] Further, the transformer T3, the signal processing module 5 and the output module 4 electrically connected to the secondary side of the transformer T4 are further included; the first winding of the transformer T3 is connected in series to the positive pole of the output module 4, one end of the second winding of the transformer T3 is connected to the GND ground terminal, and the other end of the second winding of the transformer T3 is electrically connected to the signal feedback end of the LLC control module 2 through the signal processing module 5.

[0071] In the embodiment, the feedback path composed of the transformer T3 and the signal processing module 5 (for example, rectification, noise reduction and the like) is introduced, the first winding of the transformer T3 is connected in series to the positive pole of the output module 4, when the output current of the output module 5 flows through the first winding, the second winding can proportionally (turns ratio) induct the current, after the signal processing module 5 processes, the inducted current is stably fed back to the LLC control module 2, completely replacing the traditional secondary side optocoupler feedback mode; first, the problems of temperature sensitivity, CTR drift, slow response speed and the like existing in the optocoupler are avoided, thereby the precision and stability of the output current are significantly improved, and the high-precision switching power supply is more suitable; second, the current generated by the inductive magnetic coupling is extremely small, usually maintained at the μA level, thereby the temperature rise caused by the excessive power consumption of the high-precision switching power supply is avoided, the parameter drift of the integrated device is caused, and the precision is reduced.

[0072] It should be noted that there are various circuit structures of the output module 4, which are not limited herein.

[0073] Further, the turns ratio of the first winding and the second winding of the transformer T3 is 1:100, and the first winding of the transformer T3 is only wound with one coil.

[0074] In the embodiment, since the output current of the output module 4 is usually relatively large, if the step-down transmission design is adopted, the number of coils of the first winding connected in series to the positive pole of the output module 4 is larger than the number of coils of the second winding, which will cause that the line loss is very large, the first winding generates heat seriously, and even the transformer T3 will be burned out; therefore, it is preferred that the number of coils of the first winding is smaller than the number of coils of the second winding, and the step-up design is adopted to avoid serious heat generation; and the weak current signal magnetic induction collected by the first winding is amplified to the second winding, which is also convenient for subsequent identification of the collected signal; at the same time, since the turns ratio of the first winding and the second winding is constant, the inducted signal of the second winding will also be proportional to the collected signal of the first winding, thereby the accuracy of the collected signal in the transmission process is ensured.

[0075] Therefore, the first winding is preferably only wound with one coil connected in series to the positive pole of the output module 4, and the turns ratio of the first winding and the second winding of the transformer T3 is preferably limited to 1:100, so that the line loss is very small and can be basically ignored.

[0076] Further, the LLC control module 2 comprises a diode D18, a diode D22, a resistor R16, a resistor R18, a capacitor C16, a capacitor C10, a capacitor C12 and an LLC control chip U2; the first output end and the second output end of the LLC control chip U2 are used as the driving end of the LLC control module 2, the current sampling end of the LLC control chip U2 is used as the current sampling end of the LLC control module 2, and the signal feedback end of the LLC control chip U2 is used as the signal feedback end of the LLC control module 2;

[0077] The anode of the diode D18 and the same-named end of the primary side second winding of the transformer T4 are electrically connected, the different-named end of the primary side second winding of the transformer T4 is connected with the GND ground end, the cathode of the diode D18 and one end of the resistor R18 are electrically connected, the other end of the resistor R18, one end of the resistor R16 and one end of the capacitor C12 are electrically connected with the voltage feedback end of the LLC control chip U2, and the other end of the resistor R16 and the other end of the capacitor C12 are both connected with the GND ground end;

[0078] The anode of the diode D22 and the anode of the diode D18 are electrically connected, one end of the capacitor C16 and the cathode of the diode D18 are electrically connected, the cathode of the diode D22 and one end of the capacitor C10 are electrically connected, the other end of the capacitor C10 and the other end of the capacitor C16 are both connected with the GND ground end, and the cathode of the diode D22 and the common connection point of one end of the capacitor C10 are used for externally connecting a protection signal.

[0079] In the embodiment, as shown in the figure, Figure 4 The LLC control module 2 takes the LLC control chip U2 (such as a RED2833 chip) as the core and builds a peripheral circuit, and there are various ways to set the peripheral circuit, which can be built according to the selection of the LLC control chip U2 and the chip specification book, and is not limited here.

[0080] It should be noted that based on the LLC control module 2, the mutual inductor driving triode is used to realize the related functions of the LLC module, and when the switching power supply is in the condition of no load or short circuit, the protection signal needs to be transmitted to the LLC control module 2 by the controller to realize the protection action; therefore, it is preferred to add the protection action circuit composed of the diode D22, the capacitor C16 and the capacitor C10 in the voltage feedback loop composed of the diode D18, the resistor R18, the resistor R16 and the capacitor C12, which is used for the protection signal to intervene in the voltage feedback to change the working state of the LLC control module 2, so as to realize the corresponding protection action.

[0081] Further, the signal processing module 5 comprises a diode D21, a capacitor C14, a resistor R60, a resistor R61, a resistor R57 and a capacitor C13; the other end of the second winding of the transformer T3 and the anode of the diode D21 are electrically connected, the cathode of the diode D21, one end of the capacitor C14, one end of the resistor R60, one end of the resistor R61 are electrically connected with one end of the resistor R57, the other end of the resistor R57 and one end of the capacitor C13 are electrically connected, the other end of the capacitor C14, the other end of the resistor R60, the other end of the resistor R61 and the other end of the capacitor C13 are grounded, and the other end of the resistor R57 is also electrically connected with the signal feedback end of the LLC control module 2.

[0082] In the embodiment, the diode D21 in the signal processing module 5 is used for rectification, the resistor R60 and the resistor R61 constitute a sampling resistor, and after being filtered by the RC filter composed of the resistor R57 and the capacitor C13, the signal is fed back to the CT end (i.e. the signal feedback end) of the LLC control chip U2, compared with the DIM end signal of the LLC control chip U2, and the PWM signal output is controlled to change the working frequency so as to control the output current size of the output module 2.

[0083] Other configurations and operations of the high-precision switching power supply according to the embodiment of the application are known to those skilled in the art, and will not be described in detail here.

[0084] In the description of the present specification, the description referring to the terms "embodiment", "example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do 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.

[0085] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A high-precision switching power supply comprising a PFC module and a transformer T4, characterized in that: Also include LLC control module, mutual inductor T1 and switch tube module; The PFC module and the switch tube module are electrically connected, the PFC module outputs VBUS voltage to the switch tube module, and the switch tube module and the primary side first winding of the transformer T4 are electrically connected; The driving end of the LLC control module and the input end of the mutual inductor T1 are electrically connected, and the mutual inductor T1 is electrically connected with the switch tube module;The upper and lower tubes refer to two switch tubes in the switch tube module;The LLC control module drives the upper and lower tubes of the switch tube module to be turned on or turned off through the mutual inductor T1; The current sampling end of the LLC control module and the switch tube module are electrically connected, to enable the LLC control module to drive the upper and lower tubes of the switch tube module to flip; Also include mutual inductor T3, signal processing module and output module electrically connected to the secondary side of the transformer T4;The first winding of the mutual inductor T3 is connected in series to the positive electrode of the output module, one end of the second winding of the mutual inductor T3 is connected to the GND ground end, and the other end of the second winding of the mutual inductor T3 is electrically connected to the signal feedback end of the LLC control module through the signal processing module; The LLC control module includes diode D18, diode D22, resistor R16, resistor R18, capacitor C16, capacitor C10, capacitor C12 and LLC control chip U2;The first output end and the second output end of the LLC control chip U2 are used as the driving end of the LLC control module, the current sampling end of the LLC control chip U2 is used as the current sampling end of the LLC control module, and the signal feedback end of the LLC control chip U2 is used as the signal feedback end of the LLC control module; The anode of the diode D18 and the like-named end of the primary side second winding of the transformer T4 are electrically connected, the unlike-named end of the primary side second winding of the transformer T4 is connected to the GND ground end, the cathode of the diode D18 and one end of the resistor R18 are electrically connected, the other end of the resistor R18, one end of the resistor R16 and one end of the capacitor C12 are all electrically connected to the voltage feedback end of the LLC control chip U2, and the other end of the resistor R16 and the other end of the capacitor C12 are both connected to the GND ground end; The anode of the diode D22 and the anode of the diode D18 are electrically connected, one end of the capacitor C16 and the cathode of the diode D18 are electrically connected, the cathode of the diode D22 and one end of the capacitor C10 are electrically connected, the other end of the capacitor C10 and the other end of the capacitor C16 are both connected to the GND ground end, and the common connection point of the cathode of the diode D22 and one end of the capacitor C10 is used for external connection of a protection signal.

2. The high-precision switching power supply according to claim 1, characterized in that: The switch tube module comprises a diode D4, a diode D5, a capacitor C9, a capacitor CB3, a sampling resistor RCS1, a sampling resistor RCS2, a sampling resistor RCS3 and a triode chip Q1; the triode chip Q1 comprises upper and lower triodes, which are two triodes in the triode chip Q1; the upper and lower triodes of the triode chip Q1 are used as upper and lower tubes of the switch tube module respectively; The collector of the upper triode of the triode chip Q1 and the cathode of the diode D4 are connected to the VBUS voltage, the emitter of the upper triode of the triode chip Q1 and the collector of the lower triode are electrically connected, the base of the upper triode of the triode chip Q1, the base of the lower triode of the triode chip Q1, the emitter of the upper triode of the triode chip Q1 and the anode of the diode D4 are electrically connected to the mutual inductance end of the mutual inductor T1; The same name end of the primary side first winding of the transformer T4, the anode of the diode D4 and one end of the capacitor C9 are electrically connected to the cathode of the diode D5, the other end of the capacitor C9, the anode of the diode D5, one end of the sampling resistor RCS1 and one end of the sampling resistor RCS2 are connected to the GND ground end, the different name end of the primary side first winding of the transformer T4 and one end of the capacitor CB3 are electrically connected, the other end of the capacitor CB3, the other end of the sampling resistor RCS1 and the other end of the sampling resistor RCS2 are electrically connected to one end of the sampling resistor RCS3, the other end of the sampling resistor RCS3 and the current sampling end of the LLC control module are electrically connected.

3. A high-precision switching power supply according to claim 2, characterized in that: Further comprising a resistor R3 and a resistor R4; the secondary side first winding of the mutual inductor T1 is used as the input end of the mutual inductor T1; the different name end of the secondary side second winding of the mutual inductor T1, the primary side first winding and the second winding of the mutual inductor T1 are used as the mutual inductance end of the mutual inductor T1; The same name end of the secondary side second winding of the mutual inductor T1 is connected to the GND ground end, the different name end of the secondary side second winding of the mutual inductor T1 is electrically connected to the base of the lower triode of the triode chip Q1 through the resistor R4, the same name end of the primary side first winding of the mutual inductor T1 is electrically connected to the base of the upper triode of the triode chip Q1 through the resistor R3, the emitter of the upper triode of the triode chip Q1 is electrically connected to the different name end of the primary side first winding of the mutual inductor T1 and the same name end of the primary side second winding of the mutual inductor T1, the anode of the diode D4 is electrically connected to the different name end of the primary side second winding of the mutual inductor T1.

4. A high-precision switching power supply according to claim 3, characterized in that: The turn ratio of the primary side second winding W4, the primary side first winding W3, the secondary side first winding W2 and the secondary side second winding W1 of the mutual inductor T1 is: W1: W2: W3: W4 = 5: 15: 5:

1.

5. A high-precision switching power supply according to claim 4, characterized in that: The mutual inductor T1 is a PCB mutual inductor, and the PCB mutual inductor is divided into six layers, wherein: The first layer of the PCB mutual inductor prints the coil of the secondary side first winding W2 of the mutual inductor T1, and the number of turns is five turns; The second layer of the PCB mutual inductor prints the coil of the secondary side second winding W1 of the mutual inductor T1, and the number of turns is five; The third layer of the PCB mutual inductor prints the coil of the secondary side first winding W2 of the mutual inductor T1, and the number of turns is five; The fourth layer of the PCB mutual inductor prints the coil of the primary side first winding W3 of the mutual inductor T1, and the number of turns is five; The fifth layer of the PCB mutual inductor prints the coil of the secondary side first winding W2 of the mutual inductor T1, and the number of turns is five; The sixth layer of the PCB mutual inductor prints the coil of the primary side second winding W4 of the mutual inductor T1, and the number of turns is one; The first layer, the third layer and the fifth layer of the PCB mutual inductor are connected in series.

6. The high-precision switching power supply according to claim 1, characterized in that: The number of turns of the first winding and the second winding of the mutual inductor T3 is 1:100, and the first winding of the mutual inductor T3 is only wound with one coil.

7. The high-precision switching power supply according to claim 1, characterized in that: The signal processing module comprises a diode D21, a capacitor C14, a resistor R60, a resistor R61, a resistor R57 and a capacitor C13; the other end of the second winding of the mutual inductor T3 and the anode of the diode D21 are electrically connected, the cathode of the diode D21, one end of the capacitor C14, one end of the resistor R60, one end of the resistor R61 and one end of the resistor R57 are electrically connected, the other end of the resistor R57 and one end of the capacitor C13 are electrically connected, the other end of the capacitor C14, the other end of the resistor R60, the other end of the resistor R61 and the other end of the capacitor C13 are grounded, and the other end of the resistor R57 is also electrically connected with the signal feedback end of the LLC control module. The number of turns of the first winding and the second winding of the mutual inductor T3 is 1:100, and the first winding of the mutual inductor T3 is only wound with one coil. The signal processing module comprises a diode D21, a capacitor C14, a resistor R60, a resistor R61, a resistor R57 and a capacitor C13; the other end of the second winding of the mutual inductor T3 and the anode of the diode D21 are electrically connected, the cathode of the diode D21, one end of the capacitor C14, one end of the resistor R60, one end of the resistor R61 and one end of the resistor R57 are electrically connected, the other end of the resistor R57 and one end of the capacitor C13 are electrically connected, the other end of the capacitor C14, the other end of the resistor R60, the other end of the resistor R61 and the other end of the capacitor C13 are grounded, and the other end of the resistor R57 is also electrically connected with the signal feedback end of the LLC control module.

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