Switching circuit and power adapter

Abstract

The utility model discloses a switching circuit and a power adapter, the switching circuit comprises a power input module, a resonant capacitor, a resonant inductor, a transformer, a voltage output module and a working mode control module, the voltage output module comprises a voltage output path, and an LLC mode path and an AHB mode path which are respectively connected with the voltage output path; the AHB mode path comprises a first triode, and the LLC mode path comprises a second triode; when the first triode is conducted and the second triode is cut off, the switching circuit works in an AHB mode; when the first triode is cut off and the second triode is conducted, the switching circuit works in an LLC mode. According to the utility model, the advantages of the LLC topology and the AHB topology are integrated, the LLC topology can be adopted in high-frequency application to ensure the efficiency and EMI performance of the high-frequency application, and the AHB topology can be adopted to meet the requirement of large input and output variation range.

Description

TECHNICAL FIELD

[0001] The utility model relates to switch circuit technical field especially relates to a switch circuit and voltage adapter. BACKGROUND

[0002] At present, common switch circuits are LLC topology circuit and AHB topology circuit. Among them, LLC topology circuit has good electromagnetic interference (EMI) performance, but only near the resonance point is high in efficiency, is not applicable to wide input voltage range, and requires LLC power supply input and output variation range to be small. AHB topology circuit can meet input and output large range variation, but the efficiency of AHB topology circuit in high frequency application is poorer than LLC topology circuit, and the volume is also large. At the same time, the control strategy of AHB topology is relatively complex, and needs more fine design and debugging. SUMMARY

[0003] The utility model provides a kind of switch circuit and power adapter, to solve the technical problem that current switch circuit cannot consider efficiency and EMI performance when power supply input and output large range variation.

[0004] To solve the above technical problems, in the first aspect, the utility model provides a kind of switch circuit, including power input module, resonant capacitor, resonant inductor, transformer, voltage output module and working mode control module, and the transformer includes primary winding and secondary winding;One end of the power input module is connected with the resonant capacitor, and the resonant capacitor and the resonant inductor are connected with one end of the primary winding in series, and the other end of power input module is connected with the other end of primary winding;

[0005] The voltage output module includes voltage output path and LLC mode path and AHB mode path connected with the voltage output path respectively, the AHB mode path includes first triode, the LLC mode path includes second triode, the voltage output path, the LLC mode path and the AHB mode path are connected with the secondary winding and generate output voltage;The working mode control module receives output voltage, and is connected with the base of first triode and the base of second triode;

[0006] Among them, when the first triode is turned on and the second triode is cut off, the switch circuit works in AHB mode;When the first triode is cut off and the second triode is turned on, the switch circuit works in LLC mode.

[0007] In some embodiments, the AHB mode path further includes first diode, the LLC mode path further includes second diode, and the secondary winding includes first winding and second winding.

[0008] One end of the first transistor is connected with the voltage output channel, the other end of the first transistor is connected with one end of the first winding, the other end of the first winding is connected with the positive electrode of the first diode, and the negative electrode of the first diode is connected with the voltage output channel;

[0009] One end of the second transistor is connected with the voltage output channel, the other end of the second transistor is connected with one end of the second winding, the other end of the second winding is connected with the positive electrode of the second diode, and the negative electrode of the second diode is connected with the voltage output channel.

[0010] In some embodiments, the voltage output channel comprises a third diode and an RC circuit, and the secondary winding further comprises a third winding;

[0011] The positive electrode of the third diode is connected with one end of the third winding, the other end of the third winding is connected with one end of the first transistor, one end of the second transistor and one end of the RC circuit, and the other end of the RC circuit, the negative electrode of the first diode, the negative electrode of the second diode and the negative electrode of the third diode are connected.

[0012] In some embodiments, the working mode control module comprises a control chip, the control chip receives the output voltage, and a first pin of the control chip is connected with the base of the first transistor, and a second pin of the control chip is connected with the base of the second transistor.

[0013] In some embodiments, the voltage output channel is connected with a plurality of Buck circuits, and outputs Buck voltage, and the control chip further receives the Buck voltage.

[0014] In some embodiments, a third pin of the control chip is connected with an output voltage adjusting unit, the output voltage adjusting unit comprises a first resistor, a second resistor, a fourth diode and a third resistor, one end of the first resistor, one end of the third resistor, the negative electrode of the fourth diode and the third pin are connected, the other end of the third resistor is grounded, the other end of the first resistor, one end of the second resistor and the voltage output end of the voltage output channel are connected, and the other end of the second resistor is connected with the positive electrode of the fourth diode.

[0015] In some embodiments, the power input module comprises a power supply, a fourth triode, a fifth triode, a fifth diode, a sixth diode, a first capacitor and a second capacitor, the positive pole of the power supply is connected with the collector of the fourth triode, the negative pole of the fifth diode and one end of the first capacitor, the emitter of the fourth triode, the positive pole of the fifth diode, the other end of the first capacitor, one end of the resonant capacitor, the collector of the fifth triode, the negative pole of the sixth diode and one end of the second capacitor are connected, the emitter of the fifth triode, the positive pole of the sixth diode, the other end of the second capacitor, the other end of the primary winding and the negative pole of the power supply are connected.

[0016] In some embodiments, the transformer adopts sandwich winding method.

[0017] In some embodiments, there is a dead time between the first triode and the second triode.

[0018] The utility model also provides a power adapter, including above-mentioned switching circuit.

[0019] Compared with the prior art, the utility model at least has the following beneficial effects:

[0020] The switching circuit has the advantages of LLC topology and AHB topology, can adopt LLC topology to ensure the efficiency and EMI performance of high-frequency application, and can adopt AHB topology to meet the demand of large input and output variation range. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A structure diagram of a switching circuit shown in the utility model embodiment is shown.

[0022] Figure 2 A circuit principle diagram of a voltage output module shown in the utility model embodiment is shown.

[0023] Figure 3 An equivalent diagram of the secondary winding side of AHB mode shown in the utility model embodiment is shown.

[0024] Figure 4 An equivalent diagram of the secondary winding side of LLC mode shown in the utility model embodiment is shown.

[0025] Figure 5 A circuit structure diagram of a control chip shown in the utility model embodiment is shown.

[0026] Figure 6 A principle diagram of multiple Buck circuits shown in the utility model embodiment is shown. DETAILED DESCRIPTION

[0027] In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a variety of ways other than those described herein, and skilled in the art can make similar improvements without departing from the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0028] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. Like numbers refer to like elements throughout.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this description, the terms "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] Referring to Figure 1 , the utility model discloses a kind of schematic diagram of switching circuit, which includes power input module 1, resonant capacitor Cr, resonant inductor Lr, transformer T, voltage output module 2 and working mode control module 3, the transformer T includes primary winding and secondary winding;The one end of the power input module 1 is connected with the resonant capacitor Cr, the resonant capacitor Cr and the resonant inductor Lr are connected with the one end of the primary winding in series, and the other end of power input module 1 is connected with the other end of primary winding;

[0031] The voltage output module 2 includes voltage output path and LLC mode path and AHB mode path connected with the voltage output path respectively, the AHB mode path includes first triode Q1, the LLC mode path includes second triode Q2, the voltage output path, the LLC mode path and the AHB mode path are connected with the secondary winding and generate output voltage V0;The working mode control module 3 receives output voltage, and is connected with the base of the first triode Q1 and the base of the second triode Q2;

[0032] When the first transistor Q1 is turned on and the second transistor Q2 is turned off, the switching circuit works in the AHB mode; when the first transistor Q1 is turned off and the second transistor Q2 is turned on, the switching circuit works in the LLC mode.

[0033] In the embodiment, the working mode control module 3 controls the turning on or turning off of the first transistor Q1 and the turning on or turning off of the second transistor Q2 according to the output voltage, so as to switch the circuit to the AHB mode path or the LLC mode path, thereby combining the advantages of the LLC topology and the AHB topology, being able to use the LLC topology in high-frequency applications to ensure the efficiency and EMI performance of the high-frequency applications, and being able to use the AHB topology to meet the requirement of large input and output variation range.

[0034] Optionally, there is a dead time between the first transistor Q1 and the second transistor Q2, so as to ensure that there is a time lag in the switching process between the AHB mode and the LLC mode, thereby ensuring the normal switching of the switching circuit between the AHB mode and the LLC mode.

[0035] In some embodiments, as Figure 2 The circuit principle diagram of the voltage output module is shown, the AHB mode path further includes a first diode D1, the LLC mode path further includes a second diode D2, and the secondary winding includes a first winding and a second winding;

[0036] One end of the first transistor Q1 is connected with the voltage output path, and the other end of the first transistor Q1 is connected with one end of the first winding, the other end of the first winding is connected with the positive electrode of the first diode D1, and the negative electrode of the first diode D1 is connected with the voltage output path.

[0037] One end of the second transistor Q2 is connected with the voltage output path, and the other end of the second transistor Q2 is connected with one end of the second winding, the other end of the second winding is connected with the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected with the voltage output path.

[0038] In the embodiment, the base of the first transistor Q1 and the base of the second transistor Q2 respectively receive the level signal of the working mode control module 3, so as to control the turning on or turning off of the first transistor Q1 and the second transistor Q2; as Figure 3 The equivalent diagram of the AHB mode is shown, when the first transistor Q1 is turned on and the second transistor Q2 is turned off, the switching circuit works in the AHB mode, so as to meet the requirement of wide range input and output; as Figure 4The equivalent diagram of the LLC mode is shown. When the first triode Q1 is off and the second triode Q2 is on, the switching circuit works in the LLC mode to meet the efficiency and EMI performance requirements of high-frequency applications.

[0039] In some embodiments, as shown in Figure 2 The voltage output path includes a third diode D3 and an RC circuit, and the secondary winding further includes a third winding.

[0040] The anode of the third diode is connected to one end of the third winding, and the other end of the third winding is connected to one end of the first triode, one end of the second triode, and one end of the RC circuit. The other end of the RC circuit, the cathode of the first diode, the cathode of the second diode, and the cathode of the third diode are connected.

[0041] The anode of the third diode D3 is connected to one end of the third winding, and the other end of the third winding is connected to one end of the first triode Q1, one end of the second triode Q2, and one end of the RC circuit. The other end of the RC circuit, the cathode of the first diode D1, the cathode of the second diode D2, and the cathode of the third diode D3 are connected.

[0042] In this embodiment, as shown in Figure 3 and Figure 4 When the switching circuit works in the AHB mode or the LLC mode, the output voltage is obtained based on the voltage conversion of the transformer T and through the RC circuit composed of the first resistor R1 and the first capacitor C1.

[0043] For example, for fast charging applications, the output voltage Vo of the switching circuit has a subsequent multi-channel DCDC. In order to improve the efficiency of the DCDC, Vo must vary with the output voltage. For example, the output voltage of the PD3.1 fast charging protocol is 5V, 9V, 12V, 15V, 20V, and 28V, and the output voltage is 5V, 9V, and 12V, corresponding to Vo = 12.5V, 15V, corresponding to Vo = 15.5V, 20V, corresponding to Vo = 20.5V, and 28V, corresponding to Vo = 28.5V. Since LLC can only output a fixed voltage, in order to obtain the highest efficiency at the maximum power point, the highest voltage point can be selected, i.e. Vo = 28.5V, i.e. the LLC operating point is designed to be 28.5V. When Vo = 28.5V, the switching circuit works in the LLC mode, and its equivalent diagram is shown in Figure 3 When Vo ≠ 28.5V, the switching circuit works in the AHB mode, and its equivalent diagram is shown in Figure 4

[0044] Optionally, the transformer T adopts a sandwich winding method. As shown in Figure 3 ​and Figure 4 As shown in the figure, the transformer T is a sandwich winding when the switching circuit works in the AHB mode or LLC mode, which can effectively improve the circuit efficiency.

[0045] In some embodiments, as shown in the figure, the working mode control module 3 includes a control chip IC, the control chip IC receives the output voltage, and a first pin of the control chip IC is connected with the base of the first triode Q1, and a second pin of the control chip IC is connected with the base of the second triode Q2. Figure 5 In this embodiment, the control chip IC sends a level signal to the base of the first triode Q1 through the first pin according to the received output voltage value, so as to control the first triode Q1 to be turned on or turned off, and sends a level signal to the base of the second triode Q2 through the second pin, so as to control the second triode Q2 to be turned on or turned off.

[0046] In some embodiments, as shown in the figure, the voltage output path is connected with a plurality of Buck circuits, and outputs Buck voltages, and the control chip also receives the Buck voltages.

[0047] Figure 6 In this embodiment, the Buck circuits are connected in parallel, each Buck circuit corresponds to output a Buck voltage, and the input voltage V0 is adjusted with a plurality of Buck voltages, so as to be able to be used for the first pin and the second pin of the control chip IC to select output high level or low level.

[0048] In some embodiments, as shown in the figure, a third pin of the control chip IC is connected with an output voltage adjustment unit, the output voltage adjustment unit includes a first resistor, a second resistor, a fourth diode and a third resistor, one end of the first resistor, one end of the third resistor, a negative electrode of the fourth diode and the third pin are connected, the other end of the third resistor is grounded, the other end of the first resistor, one end of the second resistor and a voltage output end of the voltage output path are connected, and the other end of the second resistor is connected with a positive electrode of the fourth diode.

[0049] In this embodiment, the control chip IC adjusts the output voltage through optical coupling feedback, so as to meet the output voltage judgment requirement when the control chip outputs the level signal. Figure 5 In some embodiments, as shown in the figure, the voltage output path is connected with a plurality of Buck circuits, and outputs Buck voltages, and the control chip also receives the Buck voltages.

[0050] In this embodiment, the Buck circuits are connected in parallel, each Buck circuit corresponds to output a Buck voltage, and the input voltage V0 is adjusted with a plurality of Buck voltages, so as to be able to be used for the first pin and the second pin of the control chip IC to select output high level or low level.

[0051] ​Exemplarily, the output voltage of the Buck circuit is V1, V2, V3, V4, when the fast charging is used to charge the electronic devices such as mobile phones, computers and the like, Vo will be adjusted with the max value of (V1, V2, V3, V4), at this time Vo will be slightly greater than the max value of (V1, V2, V3, V4), then Vo=(V1, V2, V3, V4)max+0.5V is set, the value of (V1, V2, V3, V4)max is detected by the control chip, and then the output voltage Vo is adjusted through the optical coupling feedback, so that Vo=(V1, V2, V3, V4)max+0.5V is met. For the LLC working point selected as 28.5V for design, when Vo is less than 28.5V, it works in AHB mode, the first triode Q1 is turned on, and the second triode Q2 is cut off. When Vo=28.5V, it works in LLC mode, the first triode Q1 is cut off, and the second triode Q2 is turned on.

[0052] In some embodiments, the power input module 1 comprises a power supply, a fourth triode, a fifth triode, a fifth diode, a sixth diode, a first capacitor and a second capacitor, the positive electrode of the power supply is connected with the collector of the fourth triode, the negative electrode of the fifth diode and one end of the first capacitor, the emitter of the fourth triode, the positive electrode of the fifth diode, the other end of the first capacitor, one end of the resonance capacitor, the collector of the fifth triode, the negative electrode of the sixth diode and one end of the second capacitor are connected, the emitter of the fifth triode, the positive electrode of the sixth diode, the other end of the second capacitor, the other end of the primary winding and the negative electrode of the power supply are connected.

[0053] In some embodiments, the fourth triode and the fifth triode are arranged to adjust the resonance frequency generated between the resonance inductance Lr, the resonance capacitor Cr and the magnetizing inductance of the transformer T.

[0054] The utility model also provides a power adapter, including above-mentioned switching circuit. This power adapter can be the charger based on fast charging agreement.

[0055] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not conflict, they should be considered within the scope of the present application.

[0056] The above-described embodiments only express several implementation manners of the utility model, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the utility model patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the utility model, some modifications and improvements can be made, which are within the protection scope of the utility model. Therefore, the protection scope of the utility model patent should be subject to the appended claims.

Claims

1. A switching circuit, characterized in that, It includes a power input module, a resonant capacitor, a resonant inductor, a transformer, a voltage output module, and a working mode control module. The transformer includes a primary winding and a secondary winding. One end of the power input module is connected to the resonant capacitor, and the resonant capacitor and the resonant inductor are connected in series with one end of the primary winding. The other end of the power input module is connected to the other end of the primary winding. The voltage output module includes a voltage output path and an LLC mode path and an AHB mode path respectively connected to the voltage output path. The AHB mode path includes a first transistor, and the LLC mode path includes a second transistor. The voltage output path, the LLC mode path, and the AHB mode path are connected to the secondary winding and generate an output voltage. The operating mode control module receives the output voltage and is connected to the base of the first transistor and the base of the second transistor. When the first transistor is on and the second transistor is off, the switching circuit operates in AHB mode; when the first transistor is off and the second transistor is on, the switching circuit operates in LLC mode.

2. The switching circuit as described in claim 1, characterized in that, The AHB mode path further includes a first diode, the LLC mode path further includes a second diode, and the secondary winding includes a first winding and a second winding. One end of the first transistor is connected to the voltage output path, the other end of the first transistor is connected to one end of the first winding, the other end of the first winding is connected to the positive terminal of the first diode, and the negative terminal of the first diode is connected to the voltage output path. One end of the second transistor is connected to the voltage output path, the other end of the second transistor is connected to one end of the second winding, the other end of the second winding is connected to the positive terminal of the second diode, and the negative terminal of the second diode is connected to the voltage output path.

3. The switching circuit as described in claim 2, characterized in that, The voltage output path includes a third diode and an RC circuit, and the secondary winding also includes a third winding; The positive terminal of the third diode is connected to one end of the third winding, and the other end of the third winding is connected to one end of the first transistor, one end of the second transistor, and one end of the RC circuit. The other end of the RC circuit is connected to the negative terminal of the first diode, the negative terminal of the second diode, and the negative terminal of the third diode.

4. The switching circuit as described in claim 1, characterized in that, The operating mode control module includes a control chip, which receives the output voltage, and the first pin of the control chip is connected to the base of the first transistor, and the second pin of the control chip is connected to the base of the second transistor.

5. The switching circuit as described in claim 4, characterized in that, The voltage output path is connected to several Buck circuits and outputs Buck voltage. The control chip also receives the Buck voltage.

6. The switching circuit as described in claim 4, characterized in that, The third pin of the control chip is connected to an output voltage adjustment unit, which includes a first resistor, a second resistor, a fourth diode, and a third resistor. One end of the first resistor, one end of the third resistor, the cathode of the fourth diode, and the third pin are connected. The other end of the third resistor is grounded. The other end of the first resistor, one end of the second resistor, and the voltage output terminal of the voltage output path are connected. The other end of the second resistor is connected to the anode of the fourth diode.

7. The switching circuit as described in claim 1, characterized in that, The power input module includes a power supply, a fourth transistor, a fifth transistor, a fifth diode, a sixth diode, a first capacitor, and a second capacitor. The positive terminal of the power supply is connected to the collector of the fourth transistor, the negative terminal of the fifth diode, and one end of the first capacitor. The emitter of the fourth transistor, the positive terminal of the fifth diode, the other end of the first capacitor, one end of the resonant capacitor, the collector of the fifth transistor, the negative terminal of the sixth diode, and one end of the second capacitor are connected. The emitter of the fifth transistor, the positive terminal of the sixth diode, the other end of the second capacitor, the other end of the primary winding, and the negative terminal of the power supply are connected.

8. The switching circuit as described in claim 1, characterized in that, The transformer uses a sandwich winding method.

9. The switching circuit as described in claim 1, characterized in that, There is a dead time between the first transistor and the second transistor.

10. A power adapter, characterized in that, Includes the switching circuit as described in any one of claims 1 to 9.

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