Step-down conversion circuit and method, switching power supply and electronic product

Abstract

The invention provides a step-down conversion circuit and method, a switching power supply and an electronic product. One end of a first power tube is connected with a DC input power supply, and the other end is connected with a first end of an inductor through a second power tube; one end of the third power tube is connected with the first end of the inductor, and the other end is grounded through the fourth power tube; the first, second, third and fourth power tubes receive first, second, third and fourth switch control signals respectively, the first and fourth switch control signals are opposite in phase, and the second and third switch control signals are opposite in phase; the upper electrode of the first capacitor is connected with the connection node of the first and second power tubes, and the lower electrode is connected with the connection node of the third and fourth power tubes; the second end of the inductor is grounded through the second capacitor. The circuit response speed is increased, the efficiency is improved, and the stability and the safety are high; and the power tube and the phase inverter are integrated in one module, so that the debugging difficulty of a control program is low, and later productization and popularization are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit design, and in particular to a step-down conversion circuit, method, switching power supply and electronic product. Background Art

[0002] At present, DC / DC circuits are widely used in various household and consumer, industrial and automotive electronic products. DC / DC circuits mainly include three topological structures: BUCK (step-down), BOOST (step-up) and BUCK-BOOST (step-up and step-down). Figure 1 As shown, taking the BUCK circuit as an example, when the switch K is turned on, the input voltage Vin passes through the switch K, the inductor L and the output capacitor Cout in sequence and returns to the reference ground to form a loop. At this time, the inductor is in a charging state; when the switch K is turned off, the inductor L forms a loop with the output capacitor Cout and the freewheeling diode D, and the inductor is in a discharging state. Often, the time from the circuit being turned on to reaching the preset voltage (output voltage Vout) is too long, so it is criticized by engineers and the more common LDO (low dropout linear regulator) circuit is selected. However, the BUCK circuit has never left the stage of history with its advantages of high efficiency and low loss.

[0003] Therefore, how to speed up the speed at which the BUCK circuit reaches a preset voltage and improve the response speed and efficiency of the circuit has become one of the technical problems that those skilled in the art need to solve urgently.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a buck conversion circuit, method, switching power supply and electronic product for solving the problem in the prior art that the time from when the BUCK circuit is turned on to when the preset voltage is too long.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a step-down conversion circuit, which at least includes:

[0007] A first power tube, a second power tube, a third power tube, a fourth power tube, a first capacitor, a second capacitor and an inductor;

[0008] One end of the first power tube is connected to a DC input power supply, and the other end is connected to the first end of the inductor via the second power tube; one end of the third power tube is connected to the first end of the inductor, and the other end is grounded via the fourth power tube; the control end of the first power tube receives a first switch control signal, the control end of the second power tube receives a second switch control signal, the control end of the third power tube receives a third switch control signal, and the control end of the fourth power tube receives a fourth switch control signal, wherein the first switch control signal is inverted with the fourth switch control signal, and the second switch control signal is inverted with the third switch control signal;

[0009] The upper electrode of the first capacitor is connected to the connection node between the first power tube and the second power tube, and the lower electrode is connected to the connection node between the third power tube and the fourth power tube;

[0010] The second end of the inductor is grounded via the second capacitor.

[0011] Optionally, the first power tube, the second power tube, the third power tube and the fourth power tube are NMOS tubes.

[0012] Optionally, the step-down conversion circuit also includes a first inverter and a second inverter; the first inverter is connected between the control end of the first power tube and the control end of the fourth power tube, and the second inverter is connected between the control end of the second power tube and the control end of the third power tube.

[0013] More optionally, the first power tube, the second power tube, the third power tube, the fourth power tube, the first inverter and the second inverter are integrated together to form a power module.

[0014] To achieve the above-mentioned object and other related objects, the present invention further provides a buck conversion control method, which is implemented based on the above-mentioned buck conversion circuit, and the buck conversion control method at least includes:

[0015] The switch state of each power tube is controlled, and the voltage at the first terminal of the inductor is raised based on the first capacitor, thereby accelerating the charging speed of the buck conversion circuit.

[0016] Optionally, the control method of each power tube includes:

[0017] Mode 1: Turn off the first power tube and the second power tube, turn on the third power tube and the fourth power tube, and the inductor, the second capacitor, the fourth power tube and the third power tube form a loop;

[0018] Mode 2: turning on the first power tube and the third power tube, turning off the second power tube and the fourth power tube, the DC input power supply, the first power tube, the first capacitor, the third power tube, the inductor and the second capacitor form a loop;

[0019] Mode three: turn off the first power tube and the third power tube, turn on the second power tube and the fourth power tube, and the inductor, the second capacitor, the fourth power tube, the first capacitor and the second power tube form a loop;

[0020] Mode 4: the first power tube and the second power tube are turned on, the third power tube and the fourth power tube are turned off, and the DC input power supply, the first power tube, the second power tube, the inductor and the second capacitor form a loop.

[0021] To achieve the above-mentioned purpose and other related purposes, the present invention further provides a switching power supply, which at least includes: a controller, a load and the above-mentioned step-down conversion circuit;

[0022] The controller receives the sampling signal of the buck conversion circuit and generates a switch control signal of each power tube;

[0023] The step-down conversion circuit is connected to a DC input power supply and receives various switch control signals to output a preset voltage;

[0024] The load is connected in parallel across the second capacitor of the step-down conversion circuit.

[0025] Optionally, the switching power supply further includes an AC-to-DC circuit, which is connected to the input end of the step-down conversion circuit to convert the AC power supply into a DC input power supply.

[0026] To achieve the above-mentioned object and other related objects, the present invention further provides an electronic product, which at least includes: the above-mentioned step-down conversion circuit.

[0027] As described above, the step-down conversion circuit, method, switching power supply and electronic product of the present invention have the following beneficial effects:

[0028] 1. The buck converter circuit of the present invention adopts four power tubes to realize different working modes, so as to greatly shorten the opening time through the multi-level mode, so as to achieve the purpose of fast charging of the buck converter circuit, thereby accelerating the circuit response speed and improving efficiency.

[0029] 2. The step-down conversion circuit of the present invention adds an inverter to the hardware circuit, which completely avoids the problem of corresponding power tubes being turned on at the same time, greatly improving safety; and taking the impedance matching problem into consideration, further improving stability.

[0030] 3. In the step-down conversion circuit of the present invention, the power tube and the inverter are integrated into one module, which can reduce the difficulty of debugging the control program, increase the reliability of circuit operation, and facilitate the subsequent productization and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the BUCK circuit structure in the prior art.

[0032] Figure 2 Shown is a schematic diagram of the step-down conversion circuit of the present invention.

[0033] Figure 3 Another schematic diagram of the step-down converter circuit of the present invention is shown.

[0034] Figure 4 Shown is a schematic diagram of the working principle of the buck conversion circuit mode 1 of the present invention.

[0035] Figure 5 It is a schematic diagram showing the working principle of the buck conversion circuit mode 2 of the present invention.

[0036] Figure 6 Shown is a schematic diagram of the working principle of the buck conversion circuit mode three of the present invention.

[0037] Figure 7 Shown is a schematic diagram of the working principle of the buck conversion circuit mode 4 of the present invention.

[0038] Figure 8 Shown is a schematic structural diagram of the switching power supply of the present invention.

[0039] Component number description

[0040] 1 Buck conversion circuit

[0041] 2 Controller DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0043] See also Figure 2 to Figure 8It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0044] like Figure 2 As shown, the present invention provides a buck conversion circuit 1, and the buck conversion circuit 1 includes:

[0045] A first power tube Q1, a second power tube Q2, a third power tube Q3, a fourth power tube Q4, a first capacitor C1, a second capacitor C2 and an inductor L.

[0046] like Figure 2 As shown, one end of the first power tube Q1 is connected to the DC input power supply Vi, and the other end is connected to one end of the second power tube Q2; the other end of the second power tube Q2 is connected to the first end of the inductor L. One end of the third power tube Q3 is connected to the first end of the inductor L, and the other end is connected to one end of the fourth power tube Q4; the other end of the fourth power tube Q4 is grounded. The control end of the first power tube Q1 receives the first switch control signal ctl1, the control end of the second power tube Q2 receives the second switch control signal ctl2, the control end of the third power tube Q3 receives the third switch control signal ctl3, and the control end of the fourth power tube Q4 receives the fourth switch control signal ctl4.

[0047] Specifically, in this embodiment, the first power tube Q1, the second power tube Q2, the third power tube Q3 and the fourth power tube Q4 are NMOS tubes, with a source and a drain at both ends, and a gate at the control end, which are not described one by one here. In actual use, any device that can realize switch switching is suitable for each power tube, including but not limited to IGBT (adaptive adjustment of the corresponding relationship of each port), not limited to this embodiment.

[0048] Specifically, in the present invention, the first power tube Q1 and the fourth power tube Q4 are complementarily turned on, and the second power tube Q2 and the third power tube Q3 are complementarily turned on. Therefore, the first switch control signal ctl1 is set to be inverted with the fourth switch control signal ctl4, and the second switch control signal ctl2 is set to be inverted with the third switch control signal ctl3. As an implementation method of the present invention, in order to strictly ensure that the first power tube Q1 and the fourth power tube Q4 are not turned on at the same time, and the second power tube Q2 and the third power tube Q3 are not turned on at the same time, an inverter is set between the control ends of the first power tube Q1 and the fourth power tube Q4, and an inverter is set between the control ends of the second power tube Q2 and the third power tube Q3. Figure 3 As shown, as an example, the input end of the first inverter not1 is connected to the control end of the first power tube Q1 (receiving the first switch control signal ctl1), and the output end is connected to the control end of the fourth power tube Q4 (providing the fourth switch control signal ctl4); the input end of the second inverter not2 is connected to the control end of the second power tube Q2 (receiving the second switch control signal ctl2), and the output end is connected to the control end of the third power tube Q3 (providing the third switch control signal ct3); in actual use, the input end of the first inverter not1 can be connected to the control end of the fourth power tube Q4, and the output end is connected to the control end of the first power tube Q1; the input end of the second inverter not2 can be connected to the control end of the third power tube Q3, and the output end is connected to the control end of the second power tube Q2, so as to realize the inversion of two corresponding switch control signals.

[0049] Further, as another implementation of the present invention, the first power tube Q1, the second power tube Q2, the third power tube Q3, the fourth power tube Q4, the first inverter not1 and the second inverter not2 are integrated together to form a power module. In this embodiment, the two ends of the first power tube Q1, the second power tube Q2, the third power tube Q3 and the fourth power tube Q4 are led out, and the control ends of the first power tube Q1 and the second power tube Q2 (or the control ends of the third power tube Q3 and the fourth power tube Q4) are led out, and the lead-out ends serve as ports of the power module, and the construction of the peripheral circuit (i.e., the electrical connection of the internal and external devices of the power module) is realized through the ports of the power module. At this time, each device in the power module can be configured with a device with similar performance as needed. When in use, the power module can be directly connected to the step-down conversion circuit 1 for use, without selecting an adapted device, and without considering the welding and debugging issues between the devices. Therefore, the debugging difficulty of the hardware circuit can be greatly reduced, the reliability of the circuit operation is increased, and the product is integrated, which is convenient for later productization and promotion.

[0050] like Figure 2 As shown, the upper electrode of the first capacitor C1 is connected to the connection node of the first power tube Q1 and the second power tube Q2, and the lower electrode is connected to the connection node of the third power tube Q3 and the fourth power tube Q4. The first capacitor C1 is used for precharging the buck conversion circuit 1, and the voltage at the first terminal of the inductor L is increased by precharging, thereby accelerating the charging speed of the buck conversion circuit 1.

[0051] like Figure 2 As shown, the second end of the inductor L is grounded via the second capacitor C2.

[0052] Specifically, the inductor L and the second capacitor C2 are energy storage elements, and a preset output voltage is generated based on the on and off of each power tube. In this example, the inductor L is a filter inductor, and the second capacitor C2 is a filter capacitor. The two ends of the second capacitor C2 are connected to a load R, and the voltage across the two ends of the second capacitor C2 is the output voltage Vo.

[0053] The present invention shortens the opening time through a multi-level BUCK circuit, and realizes the purpose of fast charging of the BUCK circuit based on the on-off control of four power tubes.

[0054] like Figure 2 to Figure 7 As shown, the present invention also provides a buck conversion control method, which is implemented by using the above-mentioned buck conversion circuit 1, and the buck conversion control method includes:

[0055] The switch state of each power tube is controlled, and the voltage at the first terminal of the inductor L is raised based on the first capacitor C1, thereby accelerating the charging speed of the buck conversion circuit 1.

[0056] Specifically, the step-down conversion circuit 1 of the present invention includes four working modes:

[0057] Mode 1: If Figure 4 As shown, the first power tube Q1 and the second power tube Q2 are turned off, the third power tube Q3 and the fourth power tube Q4 are turned on, and the inductor L, the second capacitor C2, the fourth power tube Q4 and the third power tube Q3 form a loop; at this time, the inductor L is in the discharge stage, and the inductor L supplies power to the second capacitor C2; because the third power tube Q3 and the fourth power tube Q4 are turned on, the first end of the inductor L is grounded, and the first end voltage Vlev of the inductor L=0.

[0058] Mode 2: If Figure 5As shown, the first power tube Q1 and the third power tube Q3 are turned on, the second power tube Q2 and the fourth power tube Q4 are turned off, and the DC input power supply Vi, the first power tube Q1, the first capacitor C1, the third power tube Q3, the inductor L and the second capacitor C2 form a loop; at this time, the inductor L is in the charging stage, and the DC input power supply Vi supplies power to the first capacitor C1, the inductor L and the second capacitor C2; due to the existence of the first capacitor C1, the first terminal voltage of the inductor L is raised to Vlev=Vi-V1, wherein Vi is the input voltage and V1 is the voltage on the first capacitor C1.

[0059] Mode 3: Figure 6 As shown, the first power tube Q1 and the third power tube Q3 are turned off, the second power tube Q2 and the fourth power tube Q4 are turned on, and the inductor L, the second capacitor C2, the fourth power tube Q4, the first capacitor C1 and the second power tube Q2 form a loop; at this time, the inductor L is in the discharge stage, and the inductor L supplies power to the second capacitor C2 and the first capacitor C1; due to the existence of the first capacitor C1, the first terminal voltage of the inductor L is raised to Vlev=V1.

[0060] Mode 4: Figure 7 As shown, the first power tube Q1 and the second power tube Q2 are turned on, the third power tube Q3 and the fourth power tube Q4 are turned off, and the DC input power supply Vi, the first power tube Q1, the second power tube Q2, the inductor L and the second capacitor C2 form a loop; at this time, the inductor L is in the charging stage, and the DC input power supply Vi supplies power to the inductor L and the second capacitor C2; the first terminal voltage Vlev of the inductor L=Vi.

[0061] Based on the above analysis, it can be known that the switching between mode 1 and mode 2 and the switching between mode 2 and mode 4 realizes the charging of the first capacitor, and the switching between mode 1 and mode 3 and the switching between mode 3 and mode 4 realizes the discharging of the first capacitor. Regardless of the charging state or the discharging state of the first capacitor, the voltage at the first end of the inductor L can be raised, thereby accelerating the rapid charging of the buck conversion circuit 1 (accelerating the preset output voltage), thereby improving efficiency; the switching between mode 1 and mode 4 realizes the rapid adjustment of the output voltage, which can be quickly adjusted from a large voltage to a small voltage, and can also quickly obtain an output voltage that does not require pre-charging; therefore, the buck conversion circuit 1 can be controlled to switch between these four modes in combination with each switch control signal to achieve stable operation of the buck conversion circuit 1.

[0062] like Figure 8As shown, the present invention further provides a switching power supply, which includes: the buck conversion circuit 1 of the present invention, a controller 2 and a load R.

[0063] like Figure 8 As shown, the controller 2 receives a sampling signal (not shown) from the buck conversion circuit 1 and generates a switch control signal for each power tube.

[0064] like Figure 8 As shown, the buck converter circuit 1 is connected to a DC input power source Vi and receives various switch control signals to output a preset voltage Vo. The structure and working principle of the buck converter circuit 1 are described above and will not be described in detail here.

[0065] like Figure 8 As shown, the load R is connected in parallel across the second capacitor C2 of the step-down conversion circuit 1, and a stable voltage Vo is obtained from the second capacitor C2.

[0066] As another implementation of the present invention, the switching power supply further includes an AC-to-DC circuit (not shown in the figure), which is connected to the input end of the step-down conversion circuit 1 to convert the AC power supply into a DC input power supply.

[0067] The present invention further provides an electronic product, comprising: the step-down conversion circuit 1, the step-down conversion circuit 1 is used to provide a preset output voltage, and is applicable to any household, consumer, industrial and automotive electronic products, which will not be described in detail here.

[0068] The step-down conversion circuit, method, switching power supply and electronic product of the present invention are turned on through multiple levels, which greatly shortens the turn-on time and achieves the purpose of quickly charging the step-down conversion circuit; further, when the power tube and the inverter are integrated in one module, the hardware debugging process can be more secure, while reducing the difficulty of debugging the control program, increasing the reliability of circuit operation, and facilitating later productization and promotion.

[0069] In summary, the present invention provides a step-down conversion circuit, method, switching power supply and electronic product, including: a first power tube, a second power tube, a third power tube, a fourth power tube, a first capacitor, a second capacitor and an inductor; one end of the first power tube is connected to a DC input power supply, and the other end is connected to the first end of the inductor via the second power tube; one end of the third power tube is connected to the first end of the inductor, and the other end is grounded via the fourth power tube; the control end of the first power tube receives a first switch control signal, the control end of the second power tube receives a second switch control signal, the control end of the third power tube receives a third switch control signal, and the control end of the fourth power tube receives a fourth switch control signal, wherein the first switch control signal is inversely proportional to the fourth switch control signal, and the second switch control signal is inversely proportional to the third switch control signal; the upper electrode of the first capacitor is connected to the connection node of the first power tube and the second power tube, and the lower electrode is connected to the connection node of the third power tube and the fourth power tube; the second end of the inductor is grounded via the second capacitor. The step-down conversion circuit, method, switching power supply and electronic product of the present invention greatly shorten the opening time through the multi-level mode, accelerate the circuit response speed and improve the efficiency; completely avoid the problem of the corresponding power tubes being turned on at the same time, and greatly improve the stability and safety; the power tube and the inverter are integrated in one module, which can reduce the difficulty of debugging the control program and facilitate the later productization and promotion. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A step-down conversion circuit, characterized in that: The step-down conversion circuit at least comprises: A first power tube, a second power tube, a third power tube, a fourth power tube, a first capacitor, a second capacitor and an inductor; One end of the first power tube is connected to a DC input power supply, and the other end is connected to the first end of the inductor via the second power tube; one end of the third power tube is connected to the first end of the inductor, and the other end is grounded via the fourth power tube; the control end of the first power tube receives a first switch control signal, the control end of the second power tube receives a second switch control signal, the control end of the third power tube receives a third switch control signal, and the control end of the fourth power tube receives a fourth switch control signal, wherein the first switch control signal is inverted with the fourth switch control signal, and the second switch control signal is inverted with the third switch control signal; The upper electrode of the first capacitor is connected to the connection node between the first power tube and the second power tube, and the lower electrode is connected to the connection node between the third power tube and the fourth power tube; The second end of the inductor is grounded via the second capacitor.

2. The step-down converter circuit according to claim 1, characterized in that: The first power tube, the second power tube, the third power tube and the fourth power tube are NMOS tubes.

3. The step-down converter circuit according to claim 1, characterized in that: The step-down conversion circuit also includes a first inverter and a second inverter; the first inverter is connected between the control end of the first power tube and the control end of the fourth power tube, and the second inverter is connected between the control end of the second power tube and the control end of the third power tube.

4. The step-down conversion circuit according to claim 3 is characterized in that: The first power tube, the second power tube, the third power tube, the fourth power tube, the first inverter and the second inverter are integrated together to form a power module.

5. A step-down conversion control method, implemented based on the step-down conversion circuit according to any one of claims 1 to 4, characterized in that: The step-down conversion control method at least comprises: The switch state of each power tube is controlled, and the voltage at the first terminal of the inductor is raised based on the first capacitor, thereby accelerating the charging speed of the buck conversion circuit.

6. The step-down conversion control method according to claim 5, characterized in that: The control methods of each power tube include: Mode 1: Turn off the first power tube and the second power tube, turn on the third power tube and the fourth power tube, and the inductor, the second capacitor, the fourth power tube and the third power tube form a loop; Mode 2: turning on the first power tube and the third power tube, turning off the second power tube and the fourth power tube, the DC input power supply, the first power tube, the first capacitor, the third power tube, the inductor and the second capacitor form a loop; Mode three: turn off the first power tube and the third power tube, turn on the second power tube and the fourth power tube, and the inductor, the second capacitor, the fourth power tube, the first capacitor and the second power tube form a loop; Mode 4: the first power tube and the second power tube are turned on, the third power tube and the fourth power tube are turned off, and the DC input power supply, the first power tube, the second power tube, the inductor and the second capacitor form a loop.

7. A switching power supply, characterized in that: The switching power supply at least comprises: a controller, a load and a step-down conversion circuit as claimed in any one of claims 1 to 4; The controller receives the sampling signal of the buck conversion circuit and generates a switch control signal of each power tube; The step-down conversion circuit is connected to a DC input power supply and receives various switch control signals to output a preset voltage; The load is connected in parallel across the second capacitor of the buck conversion circuit.

8. The switching power supply according to claim 7, characterized in that: The switching power supply further comprises an AC-to-DC circuit, which is connected to the input end of the step-down conversion circuit and converts the AC power supply into a DC input power supply.

9. An electronic product, characterized in that: The electronic product at least comprises: a step-down conversion circuit as described in any one of claims 1-4.

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