A battery-assisted charging circuit

Abstract

This utility model relates to the field of circuit design technology, and in particular to a battery auxiliary charging circuit, comprising: a DC / DC converter, a resistor, and a BUCK step-down circuit; the first end of the resistor is connected to the battery terminal; the second end of the resistor is connected to the DC / DC converter; the BUCK step-down circuit is connected to both the battery terminal and the DC / DC converter. This utility model, by introducing a resistor into the circuit, allows the battery to undergo both rapid charging and slow charging simultaneously via the BUCK step-down circuit, thereby more fully replenishing the battery energy and bringing the battery voltage close to the output voltage of the load terminal. At the same time, the BUCK step-down circuit can effectively regulate the operating state of the DC / DC converter, ensuring the stability and efficiency of the charging process, thus simplifying the circuit structure to reduce costs, saving space, and effectively improving the battery charging performance.

Description

Technical Field

[0001] This utility model relates to the field of circuit design technology, and in particular to a battery auxiliary charging circuit. Background Technology

[0002] Existing power supply systems suffer from problems such as insufficient battery charging, premature power supply, load voltage drop, and poor charging efficiency due to space and cost constraints in microcircuit modules when using DC / DC converters and external batteries for power supply. These issues result in the battery being unable to provide sufficient voltage during power supply, affecting system reliability and the normal operation of the load equipment.

[0003] Therefore, there is an urgent need to provide a technical solution to address the above problems. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a battery auxiliary charging circuit.

[0005] A battery auxiliary charging circuit includes: a DC / DC converter, a resistor, and a BUCK step-down circuit;

[0006] The first end of the resistor is connected to the battery terminal; the second end of the resistor is connected to the DC / DC converter.

[0007] The BUCK step-down circuit is connected to both the battery terminal and the DC / DC converter.

[0008] The beneficial effects of the battery auxiliary charging circuit of this utility model are as follows:

[0009] This invention introduces a resistor into the circuit, enabling the battery to undergo both rapid charging and slow charging simultaneously via the BUCK step-down circuit. This allows for more thorough replenishment of battery energy, bringing the battery voltage closer to the output voltage at the load end. Simultaneously, the BUCK step-down circuit effectively regulates the operating state of the DC / DC converter, ensuring the stability and efficiency of the charging process. This simplifies the circuit structure, reduces costs, saves space, and effectively improves battery charging performance.

[0010] In one alternative approach, a load side is also included;

[0011] The load terminal is connected to the DC / DC converter, the second terminal of the resistor, and the BUCK step-down circuit, respectively.

[0012] In the aforementioned alternative approach, by connecting the load to the DC / DC converter, the second terminal of the resistor, and the BUCK buck circuit, the load can directly draw power from the battery or the DC / DC converter. This ensures that the load can operate continuously during charging, while the BUCK buck circuit can adjust the operating state of the DC / DC converter according to the load demand, ensuring the stability of the charging and power supply process. This design improves circuit flexibility and meets the dual needs of load and charging.

[0013] In one alternative embodiment, the BUCK buck circuit includes: a first MOSFET;

[0014] The source of the first MOS transistor is connected to the first terminal of the resistor and the battery terminal, respectively;

[0015] The drain of the first MOS transistor is connected to the second terminal of the resistor, the DC / DC converter, and the load terminal, respectively.

[0016] In the above-mentioned alternative methods, by using the first MOSFET, the circuit can more effectively control the battery charging process.

[0017] In one alternative embodiment, the BUCK buck circuit further includes a PWM controller;

[0018] The PWM controller is connected to the gate of the first MOSFET.

[0019] In the above-mentioned optional methods, the first MOSFET acts as a switch and can be precisely controlled by the PWM controller, thereby optimizing charging efficiency and stability.

[0020] In one alternative embodiment, the BUCK buck circuit further includes an inductor;

[0021] The first end of the inductor is connected to the battery end;

[0022] The second end of the inductor is connected to the source of the first MOS transistor.

[0023] Among the above-mentioned alternatives, inductors help smooth current fluctuations, improve battery charging efficiency, and reduce electromagnetic interference.

[0024] In one alternative embodiment, the BUCK buck circuit further includes a diode;

[0025] The anode of the diode is connected to the second terminal of the inductor and the source of the first MOS transistor, respectively.

[0026] The cathode of the diode is grounded.

[0027] In the above-mentioned optional methods, the function of the diode is that when the first MOSFET Q1 of the BUCK step-down circuit is turned off, the energy stored in the inductor L1 forms a freewheeling circuit to charge the battery through the battery terminal and the diode, thereby achieving the purpose of stepping down the voltage and stabilizing the charging current of the battery.

[0028] In one alternative embodiment, the BUCK buck circuit further includes: a first capacitor;

[0029] The first capacitor plate of the first capacitor is connected to the drain of the first MOS transistor;

[0030] The second capacitor plate of the first capacitor is grounded.

[0031] In the above-mentioned alternatives, the first capacitor can filter out high-frequency noise, stabilize voltage, and protect the load and battery from voltage fluctuations.

[0032] In one alternative embodiment, the BUCK buck circuit further includes a second capacitor;

[0033] The first capacitor plate of the second capacitor is connected to the battery terminal;

[0034] The second capacitor's second capacitor plate is grounded.

[0035] In the above-mentioned alternatives, the second capacitor further enhances the filtering effect, especially at the battery end, which helps stabilize the battery voltage and improve the overall circuit performance.

[0036] In one alternative approach, a second MOSFET is also included;

[0037] The source of the second MOS transistor is connected to the battery terminal;

[0038] The drain of the second MOS transistor is connected to the load terminal.

[0039] In the above-mentioned optional method, the second MOSFET is connected to the battery terminal and the load terminal, which can quickly switch the power source when needed to ensure continuous power supply to the load and prevent excessive voltage drop.

[0040] In one alternative approach, it also includes: an ideal diode controller;

[0041] The ideal diode controller is connected to the gate of the second MOS transistor.

[0042] Among the above-mentioned alternatives, the ideal diode controller can effectively reduce the voltage drop across the second MOSFET, improve power supply efficiency, and provide a stable output voltage when powered by battery.

[0043] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more obvious and understandable, specific embodiments of this utility model are given below. Attached Figure Description

[0044] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0045] Figure 1 This is a schematic diagram of a battery auxiliary charging circuit according to the present invention;

[0046] Reference numerals: 1. DC / DC converter; 2. PWM controller; 3. Battery terminal; 4. Load terminal; 5. Ideal diode controller; 6. BUCK step-down circuit; R1. Resistor; Q1. First MOSFET; Q2. Second MOSFET; L1. Inductor; D1. Diode; C1. First capacitor; C2. Second capacitor. Detailed Implementation

[0047] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be implemented in various forms and should not be limited to the embodiments set forth herein.

[0048] Figure 1 This is a schematic diagram of a battery auxiliary charging circuit according to the present invention. Figure 1 As shown, it includes: DC / DC converter 1, resistor R1, and BUCK step-down circuit 6;

[0049] The first end of the resistor R1 is connected to the battery terminal 3; the second end of the resistor R1 is connected to the DC / DC converter 1.

[0050] The BUCK step-down circuit 6 is connected to the battery terminal 3 and the DC / DC converter 1, respectively.

[0051] In this circuit, DC / DC converter 1 converts the voltage to the required voltage at load terminal 4 while simultaneously providing energy to the buck converter 6 for charging at battery terminal 3. Buck converter 6 primarily regulates and converts the voltage to achieve fast battery charging. Buck converter 6 generates corresponding PWM control signals based on the battery's charging state requirements, adjusting its duty cycle to transfer the energy provided by DC / DC converter 1 to battery terminal 3. DC / DC converter 1 converts and adjusts the input voltage according to the voltage requirements of load terminal 4 and buck converter 6, ensuring an output voltage suitable for fast battery charging, thus guaranteeing a stable voltage for both the load and the battery.

[0052] Resistor R1 is primarily used in the circuit to limit current, thereby enabling slow battery charging. Resistor R1 receives the input voltage from DC / DC converter 1, and this input voltage is current-limited by resistor R1. The resistance value of R1 determines the current flow rate. By limiting the current, resistor R1 allows the battery to charge at a slower rate, complementing the fast charging achieved by DC / DC converter 1 and enabling the battery to be fully charged. After current limiting by resistor R1, the voltage or current is limited to a level suitable for slow charging, and then the processed current or voltage is transmitted to battery terminal 3.

[0053] The BUCK step-down circuit 6 is responsible for regulating and controlling the voltage provided by the DC / DC converter 1 to ensure the stability and efficiency of the charging process. The BUCK step-down circuit 6 receives input voltage information from the DC / DC converter 1 and demand voltage information from the battery terminal 3. It then adjusts the battery charging rate through the PWM controller 2 to ensure that the voltage from the DC / DC converter 1 is converted into the voltage required by the battery terminal 3 for rapid charging, thereby controlling the magnitude and stability of the output voltage.

[0054] This utility model discloses a battery auxiliary charging circuit. By introducing a resistor R1 into the circuit, the battery can undergo both rapid charging and slow charging simultaneously with the BUCK step-down circuit 6, thereby more fully replenishing the battery energy and bringing the battery voltage close to the output voltage of the load terminal 4. At the same time, the BUCK step-down circuit 6 can effectively regulate the operating state of the DC / DC converter 1, ensuring the stability and efficiency of the charging process. This simplifies the circuit structure, reduces costs, saves space, and effectively improves the battery charging performance.

[0055] In one alternative approach, it also includes: load side 4;

[0056] The load terminal 4 is connected to the DC / DC converter 1, the second terminal of the resistor R1, and the BUCK step-down circuit 6, respectively.

[0057] Load terminal 4 receives and utilizes the converted and regulated output voltage and current to meet the power supply requirements of the actual load device. Load terminal 4 receives the converted and regulated output voltage and current from DC / DC converter 1. Furthermore, when DC / DC converter 1 loses power, load terminal 4 draws energy from the battery through an ideal diode to maintain its voltage and current. Inside load terminal 4, the load device performs normal power consumption and processing based on the received voltage and current, thereby ensuring the normal operation of the device.

[0058] In one alternative embodiment, the BUCK buck circuit 6 includes: a first MOSFET Q1;

[0059] The source of the first MOS transistor Q1 is connected to the first terminal of the resistor R1 and the battery terminal 3, respectively.

[0060] The drain of the first MOS transistor Q1 is connected to the second terminal of the resistor R1, the DC / DC converter 1, and the load terminal 4, respectively.

[0061] The first MOSFET Q1 is used to control the on / off state and adjust the magnitude of the current to manage the power transfer from the DC / DC converter 1 to the battery terminal 3. Furthermore, the source of the first MOSFET Q1 is connected to the first terminal of inductor L1 and the first terminal of diode D1, receiving the input voltage and current from the battery terminal 3. The drain of the first MOSFET Q1 is connected to the second terminal of resistor R1, the DC / DC converter 1, and the load terminal 4, respectively. The on / off state of the first MOSFET Q1 controls the current flow from the DC / DC converter 1 to the battery terminal 3.

[0062] In an alternative embodiment, the BUCK buck circuit 6 further includes a PWM controller 2;

[0063] The PWM controller 2 is connected to the gate of the first MOSFET Q1.

[0064] In this circuit, the gate of the first MOSFET Q1 is connected to the PWM controller 2, receiving a PWM control signal from the controller 2. This PWM control signal is used to control the switching on and off of the first MOSFET Q1. Internally, the first MOSFET Q1 performs current conduction or cutoff operations according to the instructions of the PWM control signal, thereby regulating and controlling the current magnitude. Through this process, the first MOSFET Q1 ensures a stable current is transmitted from the DC / DC converter 1 to the battery terminal 3 to meet the charging requirements of the battery terminal 3.

[0065] It should be noted that because the PWM controller 2 used in the BUCK buck circuit 6 has a duty cycle limitation, the voltage charging of battery terminal 3 is bottlenecked and cannot reach the required voltage. Therefore, resistor R1 is added. Resistor R1 is connected to DC / DC converter 1 and battery terminal 3. Through resistor R1, the output voltage of DC / DC converter 1 slowly charges battery terminal 3, allowing the voltage of battery terminal 3 to break through the bottleneck and make the voltage of battery terminal 3 almost equal to the output voltage of DC / DC converter 1. In this way, when the output voltage of DC / DC converter 1 is abnormal, battery terminal 3 can quickly discharge to load terminal 4 through the second MOSFET, thereby supplementing the voltage requirement of load terminal 4.

[0066] In an alternative embodiment, the BUCK buck circuit 6 further includes an inductor L1;

[0067] The first end of the inductor L1 is connected to the battery terminal 3;

[0068] The second end of the inductor L1 is connected to the source of the first MOS transistor Q1.

[0069] In this circuit, inductor L1 stores electrical energy and smooths current fluctuations to ensure stable current transmission. Furthermore, the first terminal of inductor L1 is connected to battery terminal 3, receiving voltage and current from it. The second terminal of inductor L1 is connected to the source of the first MOSFET Q1, transferring the stored electrical energy to Q1. Internally, inductor L1 utilizes its electromagnetic conversion characteristics to store or release electrical energy, transforming unstable current into stable current. Therefore, inductor L1 can stabilize the current and output the stabilized current to the source of the first MOSFET Q1, thereby helping to regulate and control current flow.

[0070] In an alternative embodiment, the BUCK buck circuit 6 further includes a diode D1;

[0071] The anode of the diode D1 is connected to the second terminal of the inductor L1 and the source of the first MOS transistor Q1, respectively.

[0072] The cathode of the diode D1 is grounded.

[0073] In this circuit, the diode serves to provide a freewheeling circuit for charging the battery when the first MOSFET in the buck converter is off. This freewheeling circuit, formed by the energy stored in inductor L1, charges the battery through the battery terminals and the diode, thus achieving voltage reduction and a stable charging current for the battery. The anode of diode D1 is connected to both the second terminal of inductor L1 and the source of the first MOSFET Q1. Furthermore, the anode of diode D1 receives current from the second terminal of inductor L1. Internally, the unidirectional conduction characteristic of diode D1 filters and controls the current direction, allowing current to flow only in one direction and preventing any reverse current flow. Through this process, diode D1 ensures unidirectional current flow. Finally, diode D1 outputs the unidirectional current, ensuring a safe and stable current flow to the source of the first MOSFET Q1, thereby protecting the circuit and maintaining its normal operation. The cathode of diode D1 is grounded (GND) and connected to the negative terminal of the battery, ensuring that any unwanted current can be safely released when diode D1 is reverse biased, thus protecting circuit components and ensuring stable circuit operation.

[0074] In one alternative embodiment, the BUCK step-down circuit 6 further includes: a first capacitor C1;

[0075] The first capacitor plate of the first capacitor C1 is connected to the drain of the first MOSFET Q1;

[0076] The second capacitor plate of the first capacitor C1 is grounded.

[0077] In this circuit, the first capacitor C1 stores charge and stabilizes the voltage to smooth voltage fluctuations and provide a stable voltage output. The first capacitor plate of C1 is connected to the drain of the first MOSFET Q1, thus receiving voltage and current. The second capacitor plate of C1 is grounded to GND, providing a reference potential. Internally, C1 stores and releases charge through its charge storage characteristics. When the voltage fluctuates, C1 can absorb excess energy or replenish energy to maintain voltage stability. Through this process, C1 smooths voltage fluctuations and maintains a stable voltage across its terminals, ensuring stable and reliable operation of the circuit.

[0078] In an alternative embodiment, the BUCK step-down circuit 6 further includes a second capacitor C2;

[0079] The first capacitor plate of the second capacitor C2 is connected to the battery terminal 3;

[0080] The second capacitor plate of the second capacitor C2 is grounded.

[0081] The second capacitor C2 stores charge and stabilizes the voltage at battery terminal 3, reducing voltage fluctuations and ensuring a stable power supply voltage for the circuit. The first capacitor plate of the second capacitor C2 is connected to battery terminal 3, receiving input voltage and current from it. The second capacitor plate of the second capacitor C2 is grounded (GND), providing a reference potential. Internally, the second capacitor C2 stores and releases charge through its charge storage characteristics. When voltage fluctuations occur at battery terminal 3, the second capacitor C2 can absorb excess energy or replenish energy to maintain voltage stability. Through this process, the second capacitor C2 smooths voltage fluctuations at battery terminal 3 and maintains a stable voltage across its terminals, ensuring reliable circuit operation under a stable power supply voltage.

[0082] It should be noted that the first capacitor C1 is connected to the drain of the first MOSFET Q1, and its main function is to handle local voltage fluctuations caused by the switching action of the first MOSFET Q1 or the dynamic operation of the circuit. During the switching process, the first MOSFET Q1 generates high-frequency noise or high-frequency fluctuations caused by transient voltage changes, thus affecting the stable operation of the circuit. By placing the first capacitor C1 close to the drain of the first MOSFET Q1, high-frequency fluctuations can be suppressed more effectively, ensuring the voltage stability of the local operating environment of the circuit. The first capacitor C1, through its charge storage and release characteristics, absorbs excess energy caused by the switching of the first MOSFET Q1 or replenishes energy, smoothing voltage fluctuations.

[0083] The second capacitor, C2, is connected to battery terminal 3. Its main function is to stabilize the voltage at battery terminal 3 and handle power fluctuations caused by battery internal resistance, load changes, or external interference. Since the voltage fluctuations at battery terminal 3 are low-frequency, the second capacitor C2 targets a wider range of power supply noise. By filtering at battery terminal 3, the second capacitor C2 can provide a more stable power supply voltage, ensuring the overall power supply stability of the circuit.

[0084] In one alternative embodiment, a second MOSFET Q2 is also included;

[0085] The source of the second MOSFET Q2 is connected to the battery terminal 3;

[0086] The drain of the second MOS transistor Q2 is connected to the load terminal 4.

[0087] The primary function of the second MOSFET Q2 is to control the power supply to the load terminal 4. Furthermore, the second MOSFET Q2 controls the current path from the battery terminal 3 to the load terminal 4. The second MOSFET Q2 receives power from the battery terminal 3, with its source connected to the battery terminal 3 to ensure that the battery voltage and current can flow into the second MOSFET Q2. When the control signal of the appropriate ideal diode D1 controller 5 is applied to the gate of the second MOSFET Q2, its drain is connected to the load terminal 4, allowing current to flow from the battery terminal 3 to the load terminal 4, providing power to the load. The second MOSFET Q2 can perform switching operations according to the control signal of the ideal diode D1 controller 5 at its gate; that is, it allows current to flow when it is on and cuts off the current when it is off, based on the level change of the control signal. Through these switching operations, the second MOSFET Q2 controls the power supply state to the load terminal 4. After processing, a stable current output is obtained and output to the load terminal 4.

[0088] In an alternative embodiment, it also includes: an ideal diode D1 controller 5;

[0089] The ideal diode D1 controller 5 is connected to the gate of the second MOS transistor Q2.

[0090] The main function of the ideal diode D1 controller 5 is to control the conduction or cutoff of the second MOSFET Q2, ensuring unidirectional current flow from battery terminal 3 to load terminal 4. The ideal diode D1 controller 5 receives and sends corresponding control signals from relevant detection or control circuits. These control signals indicate the current current direction and whether the second MOSFET Q2 needs to be turned on. The ideal diode D1 controller 5 performs logical judgment and voltage regulation based on the received control signals, controlling the conduction or cutoff state of the second MOSFET Q2 by adjusting the voltage output to its gate. When the second MOSFET Q2 needs to be turned on, the ideal diode D1 controller 5 outputs an appropriate voltage signal to its gate, turning on the second MOSFET and allowing current to flow from the source to the drain. When the second MOSFET Q2 needs to be turned off, the ideal diode D1 controller 5 lowers the gate voltage, turning off the second MOSFET Q2 and preventing current flow. Through the above processing, the ideal diode D1 controller 5 achieves precise control of the second MOSFET Q2, ensuring unidirectional current flow and reducing losses. Finally, the ideal diode D1 controller 5 outputs the regulated control signal to the gate of the second MOSFET Q2 to achieve effective control of current flow.

[0091] It should be noted that without resistor R1, DC / DC converter 1 operates normally, outputting voltage to not only power load 4 but also charge the battery through the BUCK step-down circuit 6, which consists of the first MOSFET Q1, diode D1, inductor L1, first capacitor C1, and second capacitor C2. Due to the maximum duty cycle D of the PWM controller 2... max Due to limitations, the charging voltage of the BUCK buck circuit 6 can only reach a maximum of VOUT×D. max Where VOUT is the output voltage from DC / DC converter 1 to load terminal 4. When the output of DC / DC converter 1 is abnormal, load terminal 4 will be powered by battery terminal 3 through the second MOSFET Q2. The maximum charging voltage of the battery is limited to VOUT × D. max Since the voltage drop across the second MOSFET Q2 is Vsd, when the battery is used as the power supply, the output voltage is (VOUT × D). max -Vsd). Due to D max It cannot reach 100% (the maximum is 95%), so the output voltage is too low and may not meet the requirements.

[0092] With the addition of resistor R1, the battery can be fast-charged through the BUCK buck circuit 6 while simultaneously being slowly charged via resistor R1 (resistance and power selected according to requirements). This allows the battery voltage to almost perfectly match the normal output voltage VOUT of the DC / DC converter 1. When battery terminal 3 is used as the sole power supply terminal, the output voltage is (VOUT - Vsd), where Vsd depends on the required current and the Rdson of the selected MOSFET. Vsd refers to the voltage drop between the drain and source of the selected MOSFET (also known as the on-state voltage drop); Rdson is the on-resistance of the selected MOSFET. Therefore, with the addition of resistor R1, the output voltage is high and unaffected by the D... max This limits the output voltage, thus ensuring that the output voltage meets the usage requirements.

[0093] When the output voltage drops slightly due to dynamic load or other reasons, the battery voltage can effectively supplement the output voltage, preventing the output voltage from being too low and avoiding excessive power loss.

[0094] In this circuit, DC / DC converter 1 is a power conversion circuit; PWM controller 2 is the control circuit for BUCK buck circuit 6; ideal diode controller 5 is the control circuit for the second MOSFET Q2; VOUT represents the positive terminal of the output voltage, that is, VOUT is a point with a positive potential relative to GND (ground), used to connect the positive terminal of the load; GND is the reference point for the output voltage VOUT, that is, the negative terminal of the load is connected to GND. At the same time, GND is also the negative terminal connection point of the battery, that is, the negative terminal (BATTRY-) of the battery is connected to GND; BATTRY+ is the positive terminal of the battery, providing the input voltage for the entire circuit; the first capacitor and C1 and the second capacitor C2 are both filter capacitors; the first MOSFET Q1 and the second MOSFET Q2 are both switching MOSFETs; resistor R1 is a power resistor; and inductor L1 is the inductor of BUCK buck circuit 6.

[0095] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery-assisted charging circuit, characterized by, include: DC / DC converter, resistors, BUCK step-down circuit; The first end of the resistor is connected to the battery terminal; the second end of the resistor is connected to the DC / DC converter. The BUCK step-down circuit is connected to the battery terminal and the DC / DC converter respectively; Also includes: the load side; The load terminal is connected to the DC / DC converter, the second terminal of the resistor, and the BUCK step-down circuit, respectively. It also includes: a second MOSFET; The source of the second MOS transistor is connected to the battery terminal; The drain of the second MOS transistor is connected to the load terminal.

2. A battery-assisted charging circuit according to claim 1, wherein The BUCK step-down circuit includes: a first MOSFET; The source of the first MOS transistor is connected to the first terminal of the resistor and the battery terminal, respectively; The drain of the first MOS transistor is connected to the second terminal of the resistor, the DC / DC converter, and the load terminal, respectively.

3. The battery auxiliary charging circuit according to claim 2, characterized in that, The BUCK buck circuit also includes: a PWM controller; The PWM controller is connected to the gate of the first MOSFET.

4. The battery auxiliary charging circuit according to claim 3, characterized in that, The BUCK step-down circuit also includes: an inductor; The first end of the inductor is connected to the battery end; The second end of the inductor is connected to the source of the first MOS transistor.

5. A battery auxiliary charging circuit according to claim 4, characterized in that, The BUCK step-down circuit also includes: a diode; The anode of the diode is connected to the second terminal of the inductor and the source of the first MOS transistor, respectively. The cathode of the diode is grounded.

6. A battery auxiliary charging circuit according to claim 5, characterized in that, The BUCK step-down circuit also includes: a first capacitor; The first capacitor plate of the first capacitor is connected to the drain of the first MOS transistor; The second capacitor plate of the first capacitor is grounded.

7. A battery auxiliary charging circuit according to claim 6, characterized in that, The BUCK step-down circuit also includes: a second capacitor; The first capacitor plate of the second capacitor is connected to the battery terminal; The second capacitor's second capacitor plate is grounded.

8. A battery auxiliary charging circuit according to claim 1, characterized in that, Also includes: Ideal diode controller; The ideal diode controller is connected to the gate of the second MOS transistor.

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