Buck circuit
The integration of a unidirectional conductor with a minimum 0.4V conduction voltage drop in the Buck circuit addresses the challenge of stable zero-voltage and small-current output, enhancing driver chip performance and reducing costs by increasing the duty cycle and minimizing pulse width requirements.
Patent Information
- Application Number
- CN202420138667.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-19
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2034-01-19
AI Technical Summary
Existing Buck circuits struggle to maintain stable output of zero voltage and small current during the initial stage of battery formation, particularly due to high demands on driver chips and loop dynamic response, which are difficult to meet with conventional components.
Incorporating a unidirectional conductor with a conduction voltage drop greater than or equal to 0.4V into the Buck circuit, ensuring the output capacitor voltage is not zero, thereby increasing the duty cycle and reducing the minimum pulse width requirement for the driver chip, allowing for stable output of zero voltage and small current.
The solution enables the Buck circuit to achieve a stable output of zero voltage and small current, ensuring the driver chip operates normally and meets ripple requirements, while reducing design costs and component complexity.
Smart Images
Figure CN222283084U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of power supply, and in particular to a Buck circuit. Background Art
[0002] In the field of battery formation, the charging voltage range of single lithium batteries is generally 0V-4.2V, and the charging current is 120mA~120A. The charging and discharging circuit generally adopts the Buck circuit topology, which can reduce the higher input bus voltage to the required battery voltage. However, in the initial stage of battery formation, the battery voltage is extremely low, which is close to a short circuit. In addition, since the output current in the initial stage is often very small, the output port of the charging module is also close to a short circuit. At this time, the module is required to output a constant current required for battery charging. Since the output is close to a short circuit, the module is required to output a very small PWM pulse width and a stable drive signal, which places extremely high demands on the driver chip and loop dynamic response of the Buck circuit.
[0003] For the Buck circuit with zero voltage output, the pulse width of the driver chip output is required to be very small. The driver chip used is difficult to select and it is basically difficult to meet the requirements, and zero voltage output cannot be guaranteed. Utility Model Content
[0004] The embodiment of the present application provides a Buck circuit, which can achieve stable output of zero voltage and small current of the Buck circuit, so that the output voltage and current meet the ripple requirements.
[0005] The embodiment of the present application provides a Buck circuit, including:
[0006] An input power supply, an inductor, a capacitor, a load, a first switch tube, a second switch tube, a third switch tube and a unidirectional conductor;
[0007] The drain of the first switch tube is electrically connected to the positive electrode of the input power supply, the source of the first switch tube and the drain of the second switch tube are electrically connected to one end of the inductor, the other end of the inductor is electrically connected to one end of the capacitor and the drain of the third switch tube, the source of the third switch tube is electrically connected to the anode of the unidirectional conductor, the cathode of the unidirectional conductor is electrically connected to one end of the load, and the source of the second switch tube, the other end of the capacitor and the other end of the load are electrically connected to the negative electrode of the input power supply;
[0008] The conduction voltage drop of the one-way conductor is greater than or equal to 0.4V.
[0009] In some embodiments, the unidirectional conductor is a fourth switch tube, a source of the fourth switch tube is electrically connected to a source of the third switch tube, and a drain of the fourth switch tube is electrically connected to one end of the load.
[0010] In some embodiments, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all MOS tubes.
[0011] In some embodiments, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all N-channel MOS tubes.
[0012] In some embodiments, inside the first switch tube, a first transistor is connected in parallel between the drain and the source, the drain is electrically connected to the cathode of the first transistor, and the source is electrically connected to the anode of the first transistor;
[0013] Inside the second switch tube, a second transistor is connected in parallel between the drain and the source, the drain is electrically connected to the cathode of the second transistor, and the source is electrically connected to the anode of the second transistor;
[0014] A third transistor is connected in parallel between the drain and the source inside the third switch tube, the drain is electrically connected to the cathode of the third transistor, and the source is electrically connected to the anode of the third transistor;
[0015] Inside the fourth switch tube, a fourth transistor is connected in parallel between the drain and the source, the drain is electrically connected to the cathode of the fourth transistor, and the source is electrically connected to the anode of the fourth transistor.
[0016] In some embodiments, a conduction voltage drop of the fourth transistor is greater than or equal to 0.4V.
[0017] In some embodiments, the unidirectional conductor also includes a fifth transistor, an anode of the fifth transistor is electrically connected to the source of the fourth switch tube and the anode of the fourth transistor, a cathode of the fifth transistor is electrically connected to the drain of the fourth switch tube and the cathode of the fourth transistor, a conduction voltage drop of the fifth transistor is greater than or equal to 0.4V, and a conduction voltage drop of the fifth transistor is less than the conduction voltage drop of the fourth transistor.
[0018] In some embodiments, the fifth transistor is a diode.
[0019] In some embodiments, the Buck circuit further includes a PWM controller, and the PWM controller is electrically connected to the gate of the first switch tube and the gate of the second switch tube.
[0020] In some embodiments, the unidirectional conductor is a sixth transistor, the anode of the sixth transistor is electrically connected to the source of the third switch tube, the cathode of the sixth transistor is electrically connected to one end of the load, and the on-state voltage drop of the sixth transistor is greater than or equal to 0.4V.
[0021] In the Buck circuit of the embodiment of the present application, due to the existence of the conduction voltage drop of the unidirectional conductor, the output capacitor voltage of the Buck circuit is not zero, thereby being able to increase the duty cycle required by the Buck circuit, thereby reducing the requirement for the minimum pulse width of the driver chip. The Buck circuit can achieve a stable output of zero voltage and small current, allowing the driver chip to work normally to generate a continuous signal, ensuring that the output voltage and current meet the ripple requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.
[0023] Figure 1 This is a circuit schematic diagram of the Buck circuit of an embodiment of the present application.
[0024] Figure 2 This is another circuit schematic diagram of the Buck circuit according to an embodiment of the present application.
[0025] Figure 3 Another circuit schematic diagram of the Buck circuit according to an embodiment of the present application. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.
[0027] See also Figure 1 The Buck circuit 10 provided in the embodiment of the present application includes an input power supply V1, an inductor L1, a capacitor C1, a load R1, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a unidirectional conductor E.
[0028] The drain d1 of the first switch tube Q1 is electrically connected to the positive electrode of the input power supply V1, the source s1 of the first switch tube Q1 and the drain d2 of the second switch tube Q2 are electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to one end of the capacitor C1 and the drain d3 of the third switch tube Q3, the source s3 of the third switch tube Q3 is electrically connected to the anode of the unidirectional conductor E, the cathode of the unidirectional conductor E is electrically connected to one end of the load R1, the source s2 of the second switch tube Q2, the other end of the capacitor C1 and the other end of the load R1 are electrically connected to the negative electrode of the input power supply V1. The conduction voltage drop of the unidirectional conductor E is greater than or equal to 0.4V.
[0029] In the initial stage of battery formation, since the battery voltage is extremely low and close to a short circuit, and since the output current in the initial stage is often very small, the output port of the charging module is also close to a short circuit, and the module is required to output a constant current required for battery charging. When the Buck circuit 10 is used as a charging module to charge the battery, when the battery voltage is zero and a small current is required, considering that the line impedance, the line and module connection impedance, and the line and battery connection impedance are all small, the voltage drop on the bus line is close to zero, and the module output voltage is also close to zero.
[0030] In the related art, since the PWM signal output by the module main control unit DSP does not directly drive the first switch tube Q1 and the second switch tube Q2 of the power device, it needs to be amplified by the driver chip before it can drive the first switch tube Q1 and the second switch tube Q2 of the power device. DSP can generally output high-frequency, low-duty-cycle PWM signals to meet control requirements, but the output capacity of the driver chip is relatively limited and cannot output low-duty-cycle PWM signals to meet control requirements.
[0031] The driver chip cannot meet the minimum output pulse width requirement when the battery is at zero voltage. The drive signal generated by the driver chip will be abnormal and produce a discontinuous phenomenon (also known as the "hiccup" phenomenon). Specifically, the voltage at the module output port is unstable, the output current is a discontinuous pulse current, and the output current ripple is large.
[0032] In the Buck circuit 10 of the embodiment of the present application, since the circuit output has an output pair of transistors, when the battery needs to be charged with a small current at zero voltage, the third switch tube Q3 is kept turned on and the unidirectional conductor E is turned on. Due to the conduction voltage drop of the unidirectional conductor E, the Buck circuit 10 outputs a capacitor voltage V C1 It is not zero, so that the duty cycle required by the Buck circuit 10 can be increased, thereby reducing the minimum pulse width requirement for the driver chip, so that the Buck circuit 10 can achieve a stable output of zero voltage and small current, so that the driver chip can work normally to generate a continuous signal, and ensure that the output voltage and current meet the ripple requirements.
[0033] The unidirectional conductor E may be a diode or a MOS tube, etc., which is not limited here. When the unidirectional conductor E is a diode, the anode of the unidirectional conductor E is the anode of the diode, and the cathode of the unidirectional conductor E is the cathode of the diode. When the unidirectional conductor E is a MOS tube, the anode of the unidirectional conductor E is the source of the MOS tube, and the cathode of the unidirectional conductor E is the drain of the MOS tube.
[0034] It should be noted that when the unidirectional conductor is a MOS tube, the conduction of the unidirectional conductor E refers to the conduction of the body diode in the MOS tube, that is, when the battery needs to be charged with zero voltage and small current, the third switch tube Q3 is kept turned on and the MOS tube is turned off, so that the current can flow through the body diode in the MOS tube.
[0035] In some embodiments, the Buck circuit 10 may further include a PWM controller, which is electrically connected to the gate of the first switch tube Q1 and the gate of the second switch tube Q2. In this way, the PWM controller can input a driving signal to the first switch tube Q1 and the second switch tube Q2 to control the on and off of the first switch tube Q1 and the second switch tube Q2.
[0036] Specifically, the PWM controller can output a PWM (Pulse Width Modulation) signal to the drive circuit, and the PWM signal may include an on-control signal and an off-control signal, wherein the on-control signal is used to control the first switch tube Q1 and the second switch tube Q2 to be in an on state, and the off-control signal is used to control the first switch tube Q1 and the second switch tube Q2 to be in an off state.
[0037] When the driving signal PWM1 of the first switch tube Q1 is at a high level and the driving signal PWM2 of the second switch tube Q2 is at a low level, the first switch tube Q1 is in an on state and the second switch tube Q2 is in an off state, the inductor L1 is magnetized, and the current flowing through the inductor L1 increases linearly, while charging the capacitor C1 and providing energy to the load R1.
[0038] When the driving signal PWM1 of the first switch tube Q1 is at a low level and the driving signal PWM2 of the second switch tube Q2 is at a high level, the first switch tube Q1 is in an off state, the second switch tube Q2 is in an on state, the current of the inductor L1 forms a freewheeling loop through the second switch tube Q2 to charge the load R1, and the capacitor C1 is used to maintain the stability of the voltage of the load R1 and perform filtering. Among them, the conduction ratio of the PWM1 signal in one cycle is called the duty cycle.
[0039] The load R1 can be a battery. In the field of battery formation, the charging voltage range of a single lithium battery is generally 0V-4.2V, and the charging current is 120mA-120A. When the battery needs to be charged with a small current at zero voltage, the third switch tube Q3 is turned on, and the unidirectional conductor E is turned on. The conduction voltage drop V D4 for:
[0040] V C1 -Vout=V D4
[0041] Among them, V C1 is the voltage across capacitor C1, and Vout is the voltage across load R1.
[0042] Figure 1 In the figure, the PWM1 signal and the PWM2 signal are complementary drive signals for the first switch tube Q1 and the second switch tube Q2. When the PWM signal is at a high level, the corresponding first switch tube Q1 and the second switch tube Q2 will be turned on. For example, when the PWM1 signal is at a high level, the first switch tube Q1 is in the on state; when the PWM2 signal is at a high level, the second switch tube Q2 is in the on state. Among them, a certain dead zone is set between the two PWM signals (that is, the PWM1 signal and the PWM2 signal) to prevent the first switch tube Q1 and the second switch tube Q2 from being turned on at the same time. The conduction ratio of the PWM1 signal in one cycle is called the duty cycle. In the CCM (Continuous Conduction Mode) mode, the voltage formula across the capacitor C1 of the Buck circuit 10 is:
[0043] Vin*D=V C1
[0044] Among them, Vin is the input voltage and D is the duty cycle.
[0045] According to the above two formulas, when the battery needs to be charged with a small current at zero voltage, even if the output voltage Vout is zero at this time, due to the conduction voltage drop of the unidirectional conductor E, the output capacitor C1 voltage V of the Buck circuit 10 can be C1 is not zero, thereby increasing the duty cycle required by the Buck circuit 10, that is, reducing the requirement on the minimum pulse width of the driver chip.
[0046] Since the conduction voltage drop of the unidirectional conductor E is greater than or equal to 0.4V, the output capacitor C1 voltage V of the Buck circuit 10 can be appropriately C1Greater than or equal to 0.4V, so that the duty cycle can be greatly improved, so that the minimum pulse width requirement for the driver chip is lower. At this time, the duty cycle is about 2.7%, and the minimum pulse width of most low-cost driver chips on the market can meet the zero voltage output requirement. Therefore, for the Buck circuit using a low-cost driver chip, the solution of the present application can enable the Buck circuit 10 to achieve a stable output of zero voltage and small current, so that the driver chip can generate a continuous and stable drive signal, so that the output voltage and current meet the ripple requirement, and reduce the design cost.
[0047] In some embodiments, the conduction voltage drop of the unidirectional conductor E is greater than or equal to 0.4V and less than or equal to 1.2V. In this way, it is possible to ensure that the output capacitor C1 voltage V C1 It is not zero, so as to increase the duty cycle required by the Buck circuit 10, thereby reducing the demand for the minimum pulse width of the driver chip, and also reducing the difficulty of purchasing the unidirectional conductor E.
[0048] Specifically, the conduction voltage drop of most unidirectional conductors E on the market is greater than or equal to 0.4 V and less than or equal to 1.2 V. The conduction voltage drop of the unidirectional conductor E may be 0.4 V, 0.6 V, 0.8 V, 1 V, or 1.2 V, or the conduction voltage drop of the unidirectional conductor E may be any value within the numerical range defined by any two of the above values, which is not limited here.
[0049] It should be noted that when the battery voltage increases and is not in a zero voltage state, the unidirectional conductor E can be controlled to be in a conducting state, thereby reducing the impedance and preventing the unidirectional conductor E from being in an overheated state for a long time, and the Buck circuit 10 can still work normally. In other words, the solution of the embodiment of the present application does not need to add additional circuit design, and can also meet the requirements of the full voltage output range, greatly reducing the design cost.
[0050] See also Figure 1 In some embodiments, the unidirectional conductor E is a fourth switch tube Q4, a source s4 of the fourth switch tube Q4 is electrically connected to a source s3 of the third switch tube Q3, and a drain d4 of the fourth switch tube Q4 is electrically connected to one end of the load R1. In this way, the conduction voltage drop characteristic of the fourth switch tube Q4 is used to make the output capacitor C1 voltage V C1 It is not zero, so that stable output of zero voltage and small current can be achieved, so that the output voltage and current meet the ripple requirements.
[0051] In this case, when the battery needs to be charged at a low current with a zero voltage, the third switch tube Q3 is turned on and the fourth switch tube Q4 is turned off. By turning on the body transistor of the fourth switch tube Q4, the Buck circuit 10 outputs a capacitor voltage V C1It is not zero, so that the duty cycle required by the Buck circuit 10 can be increased, thereby reducing the minimum pulse width requirement for the driver chip, so that the Buck circuit 10 can achieve a stable output of zero voltage and small current, so that the driver chip can work normally to generate a continuous signal, and ensure that the output voltage and current meet the ripple requirements.
[0052] It is worth mentioning that the source s4 of the fourth switch tube Q4 is electrically connected to the source s3 of the third switch tube Q3, the drain d4 of the fourth switch tube Q4 is electrically connected to one end of the load R1, and the drain d3 of the third switch tube Q3 is electrically connected to the other end of the inductor L1. When the third switch tube Q3 and the fourth switch tube Q4 are connected in the above manner, current reverse flow can be prevented.
[0053] In some embodiments, the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 , and the fourth switch tube Q4 are all MOS tubes.
[0054] In this way, when the first switch tube Q1 and the second switch tube Q2 are both MOS tubes (Metal-Oxide-SemiconductorField-Effect Transistor), the Buck circuit 10 can have a synchronous rectification function, and the on-resistance of the MOS tube is very low, thereby reducing the conduction loss and improving the efficiency of the Buck circuit 10. When the fourth switch tube Q4 is a MOS tube, when the battery is charged with zero voltage and low current, the third switch tube Q3 is kept turned on and the fourth switch tube Q4 is turned off. The on-voltage drop of the fourth transistor D4 can make the output capacitor C1 voltage V of the Buck circuit 10 C1 It is not zero, thereby reducing the minimum pulse width requirement of the driver chip, so that a stable output of zero voltage and small current can be achieved.
[0055] In some embodiments, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all N-channel MOS tubes. In some embodiments, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 can also be P-channel MOS tubes. The specific MOS tube type can be selected according to actual applications and is not specifically limited here.
[0056] In some embodiments, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 can also be IGBTs (insulated gate bipolar transistors) or triodes, etc. Users can select corresponding devices and perform corresponding circuit designs according to actual needs, and there is no limitation here.
[0057] In some embodiments, inside the first switch tube Q1, a first transistor D1 is connected in parallel between the drain electrode d1 and the source electrode s1, the drain electrode d1 is electrically connected to the cathode of the first transistor D1, and the source electrode s1 is electrically connected to the anode of the first transistor D1. Inside the second switch tube Q2, a second transistor D2 is connected in parallel between the drain electrode d2 and the source electrode s2, the drain electrode d2 is electrically connected to the cathode of the second transistor D2, and the source electrode s2 is electrically connected to the anode of the second transistor D2. Inside the third switch tube Q3, a third transistor D3 is connected in parallel between the drain electrode d3 and the source electrode s3, the drain electrode d3 is electrically connected to the cathode of the third transistor D3, and the source electrode s3 is electrically connected to the anode of the third transistor D3. Inside the fourth switch tube Q4, a fourth transistor D4 is connected in parallel between the drain electrode d4 and the source electrode s4, the drain electrode d4 is electrically connected to the cathode of the fourth transistor D4, and the source electrode s4 is electrically connected to the anode of the fourth transistor D4.
[0058] Thus, the first transistor D1, the second transistor D2, the third transistor D3 and the fourth transistor D4 can turn on the Buck circuit 10, and when the fourth transistor D4 is turned on, the on-state voltage drop characteristic of the fourth transistor D4 can make the output capacitor C1 voltage V C1 It is not zero, so that stable output of zero voltage and small current can be achieved, so that the output voltage and current meet the ripple requirements.
[0059] In some embodiments, the on-state voltage drop of the fourth transistor D4 is greater than or equal to 0.4V.
[0060] Thus, when the unidirectional conductor E is the fourth switch tube Q4, the conduction voltage drop of the fourth transistor D4 in the fourth switch tube Q4 can make the output capacitor C1 voltage V C1 is not zero, thereby increasing the required duty cycle and further reducing the minimum pulse width requirement of the driver chip, so that a stable output of zero voltage and small current can be achieved.
[0061] Specifically, the body diode in most MOS tubes on the market, that is, the conduction voltage drop of the fourth transistor D4 is greater than or equal to 0.4V, and when the conduction voltage drop of the fourth transistor D4 is 0.4V, the duty cycle is about 2.7%, and the minimum pulse width of most low-cost driver chips on the market can meet the zero voltage output requirement. In this way, it can not only ensure that the output capacitor C1 voltage V C1 It is not zero, so as to increase the duty cycle required by the Buck circuit 10, thereby reducing the demand for the minimum pulse width of the driving chip and reducing the difficulty of purchasing the fourth transistor D4.
[0062] See also Figure 2In some embodiments, the unidirectional conductor E further includes a fifth transistor D5, an anode of the fifth transistor D5 is electrically connected to the source s4 of the fourth switch tube Q4 and the anode of the fourth transistor D4, a cathode of the fifth transistor D5 is electrically connected to the drain d4 of the fourth switch tube Q4 and the cathode of the fourth transistor D4, a conduction voltage drop of the fifth transistor D5 is greater than or equal to 0.4V, and a conduction voltage drop of the fifth transistor D5 is less than a conduction voltage drop of the fourth transistor D4. In this way, the user can select the corresponding fifth transistor D5 according to different duty cycle requirements.
[0063] Specifically, when the fifth transistor D5 is connected in parallel with the fourth transistor D4, since the conduction voltage drop of the fifth transistor D5 is smaller than the conduction voltage drop of the fourth transistor D4, the fifth transistor D5 is turned on, and then the fifth transistor D5 can make the output capacitor C1 voltage V C1 It is not zero, thereby achieving a stable output of zero voltage and small current, so that the output voltage and current meet the ripple requirements.
[0064] In some embodiments, the on-state voltage drop of the fifth transistor D5 is greater than or equal to 0.4 V and less than or equal to 1.2 V. The on-state voltage drop of the fifth transistor D5 may be 0.4 V, 0.6 V, 0.8 V, 1 V, or 1.2 V, or the on-state voltage drop of the fifth transistor D5 may be any value within the numerical range defined by any two of the above values, which is not limited here.
[0065] In some embodiments, the fifth transistor D5 is a diode. In this way, the fifth transistor D5 can ensure that the output capacitor C1 voltage V of the Buck circuit 10 is kept constant while the circuit is turned on. C1 When the fifth transistor D5 is a diode, the cathode of the diode is electrically connected to the drain d4 of the fourth switch tube Q4 and the cathode of the fourth transistor D4, and the anode of the diode is electrically connected to the source s4 of the fourth transistor D4 and the anode of the fourth transistor D4.
[0066] See also Figure 3 In some embodiments, the unidirectional conductor E is a sixth transistor D6, an anode of the sixth transistor D6 is electrically connected to the source s3 of the third switch tube Q3, a cathode of the sixth transistor D6 is electrically connected to one end of the load R1, and a conduction voltage drop of the sixth transistor D6 is greater than or equal to 0.4V.
[0067] In this way, when the unidirectional conductor E is the sixth transistor D6, the overall control of the Buck circuit 10 can be made simpler, the control complexity of the Buck circuit 10 can be reduced, and the stable output of zero voltage and small current of the Buck circuit 10 can also be achieved.
[0068] Specifically, when the sixth transistor D6 is turned on, the on-state voltage drop characteristic of the sixth transistor D6 can make the output capacitor C1 voltage V C1 The sixth transistor D6 can be a diode, the anode of which is electrically connected to the source s3 of the third switch tube Q3, and the cathode of which is electrically connected to one end of the load R1.
[0069] In some embodiments, the on-state voltage drop of the sixth transistor D6 is greater than or equal to 0.4 V and less than or equal to 1.2 V. The on-state voltage drop of the sixth transistor D6 may be 0.4 V, 0.6 V, 0.8 V, 1 V, or 1.2 V, or the on-state voltage drop of the sixth transistor D6 may be any value within the numerical range defined by any two of the above values, which is not limited here.
[0070] In the description of this application, it should be understood that terms such as "first" and "second" are only used to distinguish similar objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.
[0071] It should be noted that in the embodiments of the present application, "electrical connection" can be achieved by direct electrical connection between two electrical components, or by indirect electrical connection. For example, A and B are electrically connected, which can be achieved by direct connection between A and B, or by indirect connection between A and B through one or more other electrical components.
[0072] The Buck circuit provided in the embodiment of the present application is described in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.
Claims
1. A Buck circuit, characterized in that: It includes an input power supply, an inductor, a capacitor, a load, a first switch tube, a second switch tube, a third switch tube and a unidirectional conductor; The drain of the first switch tube is electrically connected to the positive electrode of the input power supply, the source of the first switch tube and the drain of the second switch tube are electrically connected to one end of the inductor, the other end of the inductor is electrically connected to one end of the capacitor and the drain of the third switch tube, the source of the third switch tube is electrically connected to the anode of the unidirectional conductor, the cathode of the unidirectional conductor is electrically connected to one end of the load, and the source of the second switch tube, the other end of the capacitor and the other end of the load are electrically connected to the negative electrode of the input power supply; The conduction voltage drop of the one-way conductor is greater than or equal to 0.4V.
2. The Buck circuit according to claim 1, characterized in that: The one-way conductor is a fourth switch tube, a source of the fourth switch tube is electrically connected to a source of the third switch tube, and a drain of the fourth switch tube is electrically connected to one end of the load.
3. The Buck circuit according to claim 2, characterized in that: The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all MOS tubes.
4. The Buck circuit according to claim 3, characterized in that: The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all N-channel MOS tubes.
5. The Buck circuit according to claim 3, characterized in that: A first transistor is connected in parallel between the drain and the source inside the first switch tube, the drain is electrically connected to the cathode of the first transistor, and the source is electrically connected to the anode of the first transistor; Inside the second switch tube, a second transistor is connected in parallel between the drain and the source, the drain is electrically connected to the cathode of the second transistor, and the source is electrically connected to the anode of the second transistor; A third transistor is connected in parallel between the drain and the source inside the third switch tube, the drain is electrically connected to the cathode of the third transistor, and the source is electrically connected to the anode of the third transistor; Inside the fourth switch tube, a fourth transistor is connected in parallel between the drain and the source, the drain is electrically connected to the cathode of the fourth transistor, and the source is electrically connected to the anode of the fourth transistor.
6. The Buck circuit according to claim 5, characterized in that: The on-state voltage drop of the fourth transistor is greater than or equal to 0.4V.
7. The Buck circuit according to claim 5, characterized in that: The unidirectional conductor also includes a fifth transistor, an anode of the fifth transistor is electrically connected to the source of the fourth switch tube and the anode of the fourth transistor, a cathode of the fifth transistor is electrically connected to the drain of the fourth switch tube and the cathode of the fourth transistor, a conduction voltage drop of the fifth transistor is greater than or equal to 0.4V, and a conduction voltage drop of the fifth transistor is less than the conduction voltage drop of the fourth transistor.
8. The Buck circuit according to claim 7, characterized in that: The fifth transistor is a diode.
9. The Buck circuit according to claim 3, characterized in that: The Buck circuit also includes a PWM controller, which is electrically connected to the gate of the first switch tube and the gate of the second switch tube.
10. The Buck circuit according to claim 1, characterized in that: The unidirectional conductor is a sixth transistor, an anode of the sixth transistor is electrically connected to the source of the third switch tube, a cathode of the sixth transistor is electrically connected to one end of the load, and a conduction voltage drop of the sixth transistor is greater than or equal to 0.4V.