DC-DC circuit applied to voltage regulation mode switching

Abstract

The utility model discloses a DC-DC circuit applied to voltage regulation mode switching, which is characterized in that a control circuit controls a step-down circuit to step down the voltage accessed by a step-down switch circuit in a step-down mode, a step-up switch circuit outputs the voltage after the step-down, the step-up switch circuit boosts the voltage accessed by the step-up switch circuit in a step-up mode, and the step-down switch circuit outputs the voltage after the step-down. And the step-down switch circuit outputs the boosted voltage. Therefore, according to the utility model, the DC-DC circuit can carry out voltage reduction and voltage boosting operations on the input voltage based on the control circuit, flexible switching between a voltage reduction mode and a voltage boosting mode can be realized, the switching efficiency and the automation degree of the voltage regulation mode are improved, and the stability of the output voltage is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits, and in particular to a DC-DC circuit used for switching voltage adjustment modes. Background Art

[0002] With the rapid development of industrial technology, more and more devices need to be powered by batteries. Therefore, the charging and discharging process of the equipment is becoming more frequent. During the charging and discharging process of the equipment, the demand for switching between the boost mode and the buck mode of the DCDC circuit is becoming more and more important.

[0003] At present, the traditional DCDC circuit is divided into a unidirectional boost mode or buck mode, and a buck-boost DCDC circuit capable of switching the voltage adjustment mode. The buck-boost DCDC circuit capable of switching the voltage adjustment mode is more complicated when switching the mode and has a low degree of automation. Therefore, it is particularly important to propose a DCDC circuit that can improve the efficiency and automation of the voltage adjustment mode switching. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a DC-DC circuit applied to voltage regulation mode switching, which can realize flexible switching between buck mode and boost mode, improve the efficiency and automation of voltage regulation mode switching, and improve the stability of output voltage.

[0005] In order to solve the above technical problems, the first aspect of the utility model discloses a DC-DC circuit applied to voltage regulation mode switching, characterized in that the DC-DC circuit comprises:

[0006] A control circuit, a buck switching circuit, a boost switching circuit, and a buck circuit;

[0007] The first end of the step-down switch circuit is electrically connected to the first voltage input end of the control circuit, the first voltage output end of the control circuit is electrically connected to one end of the step-down circuit, the other end of the step-down circuit is electrically connected to the first end of the boost switch circuit, the second end of the boost switch circuit is electrically connected to the second voltage input end of the control circuit, and the second voltage output end of the control circuit is electrically connected to the second end of the step-down switch circuit;

[0008] Among them, when the mode switching control terminal of the control circuit is electrically connected to the auxiliary bias power supply output terminal of the control circuit, the voltage adjustment mode of the DC-DC circuit is the first mode, and when the mode switching control terminal of the control circuit is used for grounding, the voltage adjustment mode of the DC-DC circuit is the second mode.

[0009] As an optional implementation, in the first aspect of the utility model, the control circuit includes a control chip, and the buck switch circuit includes a first NMOS tube, a second NMOS tube and a first resistor;

[0010] The source of the first NMOS tube is electrically connected to the source of the second NMOS tube, the first voltage input terminal of the control chip, and the second voltage output terminal of the control chip, respectively; the gate of the first NMOS tube and the gate of the second NMOS tube are electrically connected to one end of the first resistor; the other end of the first resistor is electrically connected to the first gate driving terminal of the control chip; and the drain of the second NMOS tube is electrically connected to one end of the step-down circuit;

[0011] When the voltage adjustment mode is the first mode, the drain of the first NMOS tube is used to access the first input voltage; when the voltage adjustment mode is the second mode, the drain of the first NMOS tube is used to output the second output voltage.

[0012] As an optional implementation, in the first aspect of the utility model, the boost switch circuit includes a third NMOS transistor, a fourth NMOS transistor and a second resistor;

[0013] The drain of the third NMOS tube is electrically connected to the other end of the step-down circuit, the source of the third NMOS tube is electrically connected to the source of the fourth NMOS tube and the second voltage input terminal of the control chip respectively, the gate of the third NMOS tube and the gate of the fourth NMOS tube are electrically connected to one end of the second resistor, and the other end of the second resistor is electrically connected to the second gate driving terminal of the control chip;

[0014] When the voltage adjustment mode is the first mode, the drain of the fourth NMOS tube is used to output the first output voltage, and when the voltage adjustment mode is the second mode, the drain of the fourth NMOS tube is used to access the second input voltage.

[0015] As an optional implementation, in the first aspect of the utility model, the first voltage output terminal of the control chip includes a top gate drive terminal and a bottom gate drive terminal of the control chip;

[0016] The step-down circuit includes at least one MOS tube combination circuit, and the MOS tube combination circuit includes a fifth NMOS tube and a sixth NMOS tube;

[0017] The drain of the fifth NMOS tube is electrically connected to the drain of the second NMOS tube, the gate of the fifth NMOS tube is electrically connected to the top gate drive terminal of the control chip, the source of the fifth NMOS tube and the drain of the sixth NMOS tube are electrically connected to the drain of the third NMOS tube, and the gate of the sixth NMOS tube is electrically connected to the bottom gate drive terminal of the control chip;

[0018] Wherein, the source of the sixth NMOS tube is used for grounding.

[0019] As an optional implementation, in the first aspect of the utility model, the control chip includes LT8228.

[0020] As an optional implementation, in the first aspect of the utility model, the DC-DC circuit further includes a first error amplification circuit and a second error amplification circuit;

[0021] One end of the first error amplifier circuit is electrically connected to the first error amplifier terminal of the control chip, and the other end of the first error amplifier circuit is grounded; one end of the second error amplifier circuit is electrically connected to the second error amplifier terminal of the control chip, and the other end of the second error amplifier circuit is grounded;

[0022] Among them, when the voltage adjustment mode is the second mode, the first error amplifier circuit is used to amplify the error signal of the DC-DC circuit, and when the voltage adjustment mode is the first mode, the second error amplifier circuit is used to amplify the error signal of the DC-DC circuit.

[0023] As an optional implementation, in the first aspect of the utility model, the DC-DC circuit further includes a fault diagnosis circuit;

[0024] The fault diagnosis circuit includes a diagnosis circuit, a connector and a power conversion circuit;

[0025] One end of the diagnostic circuit is electrically connected to the fault diagnosis end of the control chip, the other end of the diagnostic circuit is electrically connected to one end of the connector, the other end of the connector is electrically connected to one end of the power conversion circuit, and the other end of the power conversion circuit is used to access the third input voltage;

[0026] The power conversion circuit is used to perform voltage conversion on the third input voltage to obtain a power supply voltage, and provide the power supply voltage to the diagnostic circuit.

[0027] As an optional implementation, in the first aspect of the utility model, the diagnostic circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first light-emitting diode, a second light-emitting diode and a seventh NMOS tube, and the fault diagnosis end includes a first sub-fault diagnosis end and a second sub-fault diagnosis end;

[0028] One end of the third resistor is electrically connected to the first sub-fault diagnosis end, the other end of the third resistor is electrically connected to one end of the fourth resistor, one end of the fifth resistor, one end of the sixth resistor and one end of the connector respectively, the other end of the fourth resistor is electrically connected to the positive electrode of the first light-emitting diode, the negative electrode of the first light-emitting diode is electrically connected to the second sub-fault diagnosis end, the other end of the fifth resistor is electrically connected to the mode switching control end and the gate of the seventh NMOS tube respectively, the other end of the sixth resistor is electrically connected to the positive electrode of the second light-emitting diode, the negative electrode of the second light-emitting diode is electrically connected to the drain of the seventh NMOS tube, and the source of the seventh NMOS tube is used for grounding.

[0029] The implementation of this utility model has the following beneficial effects:

[0030] In the utility model, the control circuit can control the step-down circuit in the step-down mode to step down the voltage connected to the step-down switch circuit, and the step-up switch circuit outputs the stepped-down voltage. In the step-up mode, the voltage connected to the step-up switch circuit is stepped up, and the step-down switch circuit outputs the stepped-up voltage. It can be seen that the utility model can realize the step-down and step-up operations of the DC-DC circuit on the input voltage based on the control circuit, can realize flexible switching between the step-down mode and the step-up mode, improve the switching efficiency and automation of the voltage adjustment mode, and improve the stability of the output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a structural schematic diagram of a DC-DC circuit applied to voltage regulation mode switching disclosed in an embodiment of the utility model;

[0033] Figure 2 It is a structural schematic diagram of another DC-DC circuit used for voltage regulation mode switching disclosed in an embodiment of the utility model;

[0034] Figure 3It is a structural schematic diagram of a step-down switch circuit disclosed in an embodiment of the utility model;

[0035] Figure 4 It is a structural schematic diagram of a boost switch circuit disclosed in an embodiment of the utility model;

[0036] Figure 5 It is a structural schematic diagram of a step-down circuit disclosed in an embodiment of the utility model;

[0037] Figure 6 It is a structural schematic diagram of a diagnostic circuit disclosed in an embodiment of the utility model;

[0038] Figure 7 It is a structural schematic diagram of a control chip disclosed in an embodiment of the utility model;

[0039] Figure 8 It is a structural schematic diagram of a current limiting circuit disclosed in an embodiment of the utility model;

[0040] Fig. 9 This is a structural schematic diagram of another DC-DC circuit used for voltage regulation mode switching disclosed in an embodiment of the utility model. DETAILED DESCRIPTION

[0041] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that, unless otherwise clearly specified and limited, the term "electrical connection" in the specification and claims of the utility model and the above-mentioned drawings should be understood in a broad sense. For example, it can be a fixed electrical connection, a detachable electrical connection, or an integral electrical connection; it can be a mechanical electrical connection, an electrical electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. In addition, the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. The terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For those of ordinary skill in the art, the specific meanings of the above terms in the utility model can be understood according to specific circumstances.

[0043] The utility model discloses a DC-DC circuit applied to voltage regulation mode switching, which can realize the step-down and step-up operation of the DC-DC circuit on the input voltage based on the control circuit, can realize flexible switching between the step-down mode and the step-up mode, improve the efficiency and automation of voltage regulation mode switching, and improve the stability of the output voltage. The following are detailed descriptions respectively.

[0044] Embodiment 1

[0045] See also Figure 1 , Figure 1 1 is a schematic diagram of a DC-DC circuit for switching a voltage regulation mode disclosed in an embodiment of the utility model. Figure 1 The DC-DC circuit used for voltage adjustment mode switching can be applied to the field of digital power supply in computer rooms, and the embodiments of the utility model are not limited thereto. Figure 1 As shown, the DC-DC circuit applied to voltage regulation mode switching may include:

[0046] Control circuit 101, buck switch circuit 201, boost switch circuit 301 and buck circuit 401;

[0047] A first end of the step-down switch circuit 201 is electrically connected to a first voltage input end of the control circuit 101, a first voltage output end of the control circuit 101 is electrically connected to one end of the step-down circuit 401, the other end of the step-down circuit 401 is electrically connected to a first end of the boost switch circuit 301, a second end of the boost switch circuit 301 is electrically connected to a second voltage input end of the control circuit 101, and a second voltage output end of the control circuit 101 is electrically connected to a second end of the step-down switch circuit 201;

[0048] Among them, when the mode switching control terminal of the control circuit 101 is electrically connected to the auxiliary bias power supply output terminal of the control circuit 101, the voltage adjustment mode of the DC-DC circuit is the first mode, and when the mode switching control terminal of the control circuit 101 is used for grounding, the voltage adjustment mode of the DC-DC circuit is the second mode.

[0049] In this optional embodiment, optionally, the first mode of the DC-DC circuit can be a buck mode. When the voltage adjustment mode of the DC-DC circuit is the buck mode, the third end of the buck switch circuit is used to connect to the first input voltage, and the third end of the boost switch circuit is used to output the first output voltage. The first output voltage is the voltage obtained after the DC-DC circuit performs a buck operation on the first input voltage, that is, the first input voltage can be bucked to the first output voltage through the DC-DC circuit, wherein the voltage range of the first input voltage can be 36-56V, the voltage range of the first output voltage can be 11.8-12.2V, the typical value is 12V, and the maximum output current can be It is 35A, and the second mode of the DC-DC circuit can be a boost mode. When the voltage adjustment mode of the DC-DC circuit is the boost mode, the third end of the boost switch circuit is used to connect to the second input voltage, and the third end of the buck switch circuit is used to output the second output voltage. The second output voltage is the voltage obtained after the DC-DC circuit performs a boost operation on the second input voltage, that is, the second input voltage can be boosted to the second output voltage by the DC-DC circuit, wherein the voltage range of the second input voltage can be 8-14V, the voltage range of the second output voltage can be 47-49V, the typical value is 48V, and the maximum output current can be 7A, which is not limited in this embodiment.

[0050] It can be seen that the implementation Figure 1 The described DC-DC circuit applied to voltage regulation mode switching can realize the step-down and step-up operations of the DC-DC circuit on the input voltage based on the control circuit, can realize flexible switching between the step-down mode and the step-up mode, improve the efficiency and automation of voltage regulation mode switching, and improve the stability of the output voltage.

[0051] In an optional embodiment, if Figure 2 As shown, the control circuit 101 includes a control chip 1011. The DC-DC circuit applied to the voltage adjustment mode switching may also include:

[0052] A first error amplifier circuit 501 and a second error amplifier circuit 601;

[0053] One end of the first error amplifier circuit 501 is electrically connected to the first error amplifier terminal of the control chip 1011, and the other end of the first error amplifier circuit 501 is grounded; one end of the second error amplifier circuit 601 is electrically connected to the second error amplifier terminal of the control chip 1011, and the other end of the second error amplifier circuit 601 is grounded;

[0054] When the voltage adjustment mode is the second mode, the first error amplifier circuit 501 is used to amplify the error signal of the DC-DC circuit. When the voltage adjustment mode is the first mode, the second error amplifier circuit 601 is used to amplify the error signal of the DC-DC circuit.

[0055] In this optional embodiment, optionally, the control chip may include LT8228, which is not limited in this embodiment.

[0056] It can be seen that this optional embodiment can improve the accuracy of judging the error signal in the DC-DC circuit by amplifying the error signal of the DC-DC circuit in the boost mode and the buck mode respectively through the first error amplifier circuit and the second error amplifier circuit.

[0057] In another optional embodiment, Figure 2 As shown, the DC-DC circuit also includes a fault diagnosis circuit 701;

[0058] The fault diagnosis circuit 701 includes a diagnosis circuit 7011, a connector 7012 and a power conversion circuit 7013;

[0059] One end of the diagnostic circuit 7011 is electrically connected to the fault diagnosis end of the control chip 1011, the other end of the diagnostic circuit 7011 is electrically connected to one end of the connector 7012, the other end of the connector 7012 is electrically connected to one end of the power conversion circuit 7013, and the other end of the power conversion circuit 7013 is used to access the third input voltage;

[0060] The power conversion circuit is used to perform voltage conversion on the third input voltage to obtain a power supply voltage, and provide the power supply voltage to the diagnosis circuit.

[0061] It can be seen that this optional embodiment can diagnose the fault information of the DC-DC circuit through the fault diagnosis circuit, thereby improving the operating safety and stability of the DC-DC circuit.

[0062] Embodiment 2

[0063] See also Figure 3 , Figure 3 This is a schematic diagram of a buck switch circuit disclosed in an embodiment of the utility model. Figure 3 The step-down switch circuit shown can be applied to the field of digital power supply in computer rooms, and the embodiments of the present utility model are not limited thereto. Figure 3 As shown, the buck switch circuit 201 may include:

[0064] The step-down switch circuit 201 includes a first NMOS transistor M1, a second NMOS transistor M2 and a first resistor R1;

[0065] The source of the first NMOS transistor M1 is electrically connected to the source of the second NMOS transistor M2, the first voltage input terminal V1 of the control chip 1011, and the second voltage output terminal V1 of the control chip 1011, respectively; the gate of the first NMOS transistor M1 and the gate of the second NMOS transistor M2 are electrically connected to one end of the first resistor R1; the other end of the first resistor R1 is electrically connected to the first gate driving terminal DG1 of the control chip 1011; the drain of the second NMOS transistor M2 is electrically connected to one end of the step-down circuit 401;

[0066] When the voltage adjustment mode is the first mode, the drain of the first NMOS tube M1 is used to access the first input voltage, and when the voltage adjustment mode is the second mode, the drain of the first NMOS tube M1 is used to output the second output voltage.

[0067] In this optional embodiment, optionally, the first voltage input terminal and the second voltage output terminal of the control chip can both be the V1 pin of the control chip, that is, when the voltage adjustment mode is the buck mode, the V1 pin is used to input the first input voltage that needs to be bucked, and when the voltage adjustment mode is the boost mode, the V1 pin is used to output the second output voltage after boosting, which is not limited in this embodiment.

[0068] It can be seen that this optional embodiment can input a first input voltage in the buck mode and output a second output voltage in the boost mode through the buck switching circuit. It can prevent negative current and control surges in the buck and boost modes, provide isolation protection for the terminals, and improve the overall safety and stability of the DC-DC circuit.

[0069] In an optional embodiment, if Figure 4 As shown, Figure 4 Schematic diagram of a boost switch circuit disclosed in an embodiment of the utility model. Figure 4 As shown, the boost switch circuit 301 includes a third NMOS transistor M3, a fourth NMOS transistor M4 and a second resistor R2;

[0070] The drain of the third NMOS transistor M3 is electrically connected to the other end of the step-down circuit 401, the source of the third NMOS transistor M3 is electrically connected to the source of the fourth NMOS transistor M4 and the second voltage input terminal V2 of the control chip 1011, the gate of the third NMOS transistor M3 and the gate of the fourth NMOS transistor M4 are electrically connected to one end of the second resistor R2, and the other end of the second resistor R2 is electrically connected to the second gate driving terminal DG2 of the control chip 1011;

[0071] When the voltage adjustment mode is the first mode, the drain of the fourth NMOS tube M4 is used to output the first output voltage, and when the voltage adjustment mode is the second mode, the drain of the fourth NMOS tube M4 is used to access the second input voltage.

[0072] It can be seen that this optional embodiment can output the first output voltage in the buck mode and input the second input voltage in the boost mode through the boost switching circuit. It can prevent negative current and control surges in the buck and boost modes, provide isolation protection for the terminals, and improve the overall safety and stability of the DC-DC circuit.

[0073] In another optional embodiment, Figure 5 As shown, Figure 5 Schematic diagram of a step-down circuit disclosed in an embodiment of the utility model, such as Figure 5 As shown, the first voltage output terminal of the control chip 1011 includes a top gate driving terminal TG and a bottom gate driving terminal BG of the control chip 1011;

[0074] The step-down circuit 401 includes at least one MOS transistor combination circuit 4011, and the MOS transistor combination circuit 4011 includes a fifth NMOS transistor M5 and a sixth NMOS transistor M6;

[0075] The drain of the fifth NMOS tube M5 is electrically connected to the drain of the second NMOS tube M2, the gate of the fifth NMOS tube M5 is electrically connected to the top gate drive terminal TG of the control chip 1011, the source of the fifth NMOS tube M5 and the drain of the sixth NMOS tube M6 are electrically connected to the drain of the third NMOS tube M3, and the gate of the sixth NMOS tube M6 is electrically connected to the bottom gate drive terminal BG of the control chip 1011;

[0076] The source of the sixth NMOS transistor M6 is grounded.

[0077] It can be seen that this optional embodiment can realize the step-down circuit of the DC-DC circuit through at least one group of MOS tube combination circuits, which can improve the overall current carrying capacity of the circuit, increase the power that the circuit can withstand, and thus improve the circuit stability.

[0078] In yet another optional embodiment, Figure 6 As shown, Figure 6 A schematic diagram of the structure of a diagnostic circuit disclosed in an embodiment of the utility model is shown in FIG. Figure 6 As shown, the diagnostic circuit 7011 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first light-emitting diode D1, a second light-emitting diode D2 and a seventh NMOS tube M7, and the fault diagnosis terminal includes a first sub-fault diagnosis terminal REPORT and a second sub-fault diagnosis terminal FAULT;

[0079] One end of the third resistor R3 is electrically connected to the first sub-fault diagnosis terminal REPORT, the other end of the third resistor R3 is respectively electrically connected to one end of the fourth resistor R4, one end of the fifth resistor R5, one end of the sixth resistor R6 and one end of the connector 7012, the other end of the fourth resistor R4 is electrically connected to the anode of the first light-emitting diode D1, the cathode of the first light-emitting diode D1 is electrically connected to the second sub-fault diagnosis terminal FAULT, the other end of the fifth resistor R5 is respectively electrically connected to the mode switching control terminal DRXN and the gate of the seventh NMOS tube M7, the other end of the sixth resistor R6 is electrically connected to the anode of the second light-emitting diode D2, the cathode of the second light-emitting diode D2 is electrically connected to the drain of the seventh NMOS tube M7, and the source of the seventh NMOS tube M7 is used for grounding.

[0080] It can be seen that this optional embodiment can diagnose the fault information of the DC-DC circuit through the fault diagnosis circuit, thereby improving the operating safety and stability of the DC-DC circuit.

[0081] It should be noted that for information on other pins of the control chip 1011, please refer to Figure 7 , wherein the control chip 1011 can be input and output current limited by programming the pins ISET1P, ISET1N, ISET2P and ISET2N. Taking the pin ISET1P as an example, the current limiting circuit connected to the pin ISET1P can be as follows Figure 8 As shown, Figure 8 Schematic diagram of a current limiting circuit disclosed in an embodiment of the utility model, such as Figure 8 As shown, the current limiting circuit may include a seventh resistor R7 and an inductor C1, wherein the seventh resistor R7 is used for current limiting, and the inductor C1 is used for filtering.

[0082] It should be noted that the overall circuit diagram of the DC-DC circuit and other connection relationships can be found in Fig. 9 .

[0083] The above is a detailed introduction to a DC-DC circuit for switching voltage adjustment modes disclosed in an embodiment of the present invention. Specific embodiments are used in this article to illustrate the principles and implementation methods of the present invention, but the above preferred embodiments are not used to limit the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, based on the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be based on the scope defined in the claims.

Claims

1. A DC-DC circuit for switching voltage regulation modes, characterized in that: The DC-DC circuit comprises: A control circuit, a buck switching circuit, a boost switching circuit, and a buck circuit; The first end of the step-down switch circuit is electrically connected to the first voltage input end of the control circuit, the first voltage output end of the control circuit is electrically connected to one end of the step-down circuit, the other end of the step-down circuit is electrically connected to the first end of the boost switch circuit, the second end of the boost switch circuit is electrically connected to the second voltage input end of the control circuit, and the second voltage output end of the control circuit is electrically connected to the second end of the step-down switch circuit; Among them, when the mode switching control terminal of the control circuit is electrically connected to the auxiliary bias power supply output terminal of the control circuit, the voltage adjustment mode of the DC-DC circuit is the first mode, and when the mode switching control terminal of the control circuit is used for grounding, the voltage adjustment mode of the DC-DC circuit is the second mode.

2. The DC-DC circuit for switching voltage regulation modes according to claim 1, characterized in that: The control circuit includes a control chip, and the buck switch circuit includes a first NMOS transistor, a second NMOS transistor and a first resistor; The source of the first NMOS tube is electrically connected to the source of the second NMOS tube, the first voltage input terminal of the control chip, and the second voltage output terminal of the control chip, respectively; the gate of the first NMOS tube and the gate of the second NMOS tube are electrically connected to one end of the first resistor; the other end of the first resistor is electrically connected to the first gate driving terminal of the control chip; and the drain of the second NMOS tube is electrically connected to one end of the step-down circuit; When the voltage adjustment mode is the first mode, the drain of the first NMOS tube is used to access the first input voltage; when the voltage adjustment mode is the second mode, the drain of the first NMOS tube is used to output the second output voltage.

3. The DC-DC circuit for switching voltage regulation modes according to claim 2, characterized in that: The boost switch circuit includes a third NMOS transistor, a fourth NMOS transistor and a second resistor; The drain of the third NMOS tube is electrically connected to the other end of the step-down circuit, the source of the third NMOS tube is electrically connected to the source of the fourth NMOS tube and the second voltage input terminal of the control chip respectively, the gate of the third NMOS tube and the gate of the fourth NMOS tube are electrically connected to one end of the second resistor, and the other end of the second resistor is electrically connected to the second gate driving terminal of the control chip; When the voltage adjustment mode is the first mode, the drain of the fourth NMOS tube is used to output the first output voltage, and when the voltage adjustment mode is the second mode, the drain of the fourth NMOS tube is used to access the second input voltage.

4. The DC-DC circuit for switching voltage regulation modes according to claim 3, characterized in that: The first voltage output terminal of the control chip includes a top gate drive terminal and a bottom gate drive terminal of the control chip; The step-down circuit includes at least one MOS tube combination circuit, and the MOS tube combination circuit includes a fifth NMOS tube and a sixth NMOS tube; The drain of the fifth NMOS tube is electrically connected to the drain of the second NMOS tube, the gate of the fifth NMOS tube is electrically connected to the top gate drive terminal of the control chip, the source of the fifth NMOS tube and the drain of the sixth NMOS tube are electrically connected to the drain of the third NMOS tube, and the gate of the sixth NMOS tube is electrically connected to the bottom gate drive terminal of the control chip; Wherein, the source of the sixth NMOS tube is used for grounding.

5. The DC-DC circuit for switching voltage regulation modes according to any one of claims 2 to 4, characterized in that: The control chip includes LT8228.

6. The DC-DC circuit for switching voltage regulation modes according to claim 3 or 4, characterized in that: The DC-DC circuit also includes a first error amplifier circuit and a second error amplifier circuit; One end of the first error amplifier circuit is electrically connected to the first error amplifier terminal of the control chip, and the other end of the first error amplifier circuit is grounded; one end of the second error amplifier circuit is electrically connected to the second error amplifier terminal of the control chip, and the other end of the second error amplifier circuit is grounded; Among them, when the voltage adjustment mode is the second mode, the first error amplifier circuit is used to amplify the error signal of the DC-DC circuit, and when the voltage adjustment mode is the first mode, the second error amplifier circuit is used to amplify the error signal of the DC-DC circuit.

7. The DC-DC circuit for switching voltage regulation modes according to any one of claims 2 to 4, characterized in that: The DC-DC circuit also includes a fault diagnosis circuit; The fault diagnosis circuit includes a diagnosis circuit, a connector and a power conversion circuit; One end of the diagnostic circuit is electrically connected to the fault diagnosis end of the control chip, the other end of the diagnostic circuit is electrically connected to one end of the connector, the other end of the connector is electrically connected to one end of the power conversion circuit, and the other end of the power conversion circuit is used to access the third input voltage; The power conversion circuit is used to perform voltage conversion on the third input voltage to obtain a power supply voltage, and provide the power supply voltage to the diagnostic circuit.

8. The DC-DC circuit for switching voltage regulation modes according to claim 7, characterized in that: The diagnostic circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first light emitting diode, a second light emitting diode and a seventh NMOS tube, and the fault diagnosis terminal includes a first sub-fault diagnosis terminal and a second sub-fault diagnosis terminal; One end of the third resistor is electrically connected to the first sub-fault diagnosis end, the other end of the third resistor is electrically connected to one end of the fourth resistor, one end of the fifth resistor, one end of the sixth resistor and one end of the connector respectively, the other end of the fourth resistor is electrically connected to the positive electrode of the first light-emitting diode, the negative electrode of the first light-emitting diode is electrically connected to the second sub-fault diagnosis end, the other end of the fifth resistor is electrically connected to the mode switching control end and the gate of the seventh NMOS tube respectively, the other end of the sixth resistor is electrically connected to the positive electrode of the second light-emitting diode, the negative electrode of the second light-emitting diode is electrically connected to the drain of the seventh NMOS tube, and the source of the seventh NMOS tube is used for grounding.

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