Automatic buck-boost control circuit based on DCDC control chip

Abstract

The embodiment of the invention discloses an automatic buck-boost control circuit based on a DCDC control chip, the automatic buck-boost of the circuit is realized through a power supply control chip, and the PWM output duty ratio of a switch is adjusted by continuously repeating the charging and discharging processes and combining a voltage feedback circuit and the control chip, so that the automatic buck-boost of the circuit is realized. The relation between the output voltage and the input voltage is controlled, and stable output voltage is obtained at the two ends of the output capacitor. The embodiment of the invention has a wider input voltage range, the input voltage can be higher than or lower than the output voltage, when the input voltage fluctuates between higher and lower than the output voltage, the output voltage has no switching jitter, the stable voltage can be continuously output, the circuit is suitable for the application scene of battery power supply, the circuit is simple and small, the cost is low, and the PCB area is saved. Working is stable and reliable, and ripples are low.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of buck-boost power supplies, and more particularly to an automatic buck-boost control circuit based on a DCDC control chip. Background Art

[0002] Buck-boost power supply technology is a DC-DC conversion circuit that can automatically adjust the output voltage to be higher or lower than the input voltage. It combines the advantages of buck and boost circuits and can automatically achieve voltage stabilization according to the input voltage and load requirements to output the required voltage.

[0003] The core of this technology lies in the power controller chip, which integrates multiple components such as control circuits and protection circuits in a single chip, simplifying the circuit design. At the same time, the buck-boost chip can automatically adjust the output voltage according to the input voltage and load requirements to ensure a stable output voltage under different conditions, solving the power loss problem caused by the separate design of traditional buck and boost circuits.

[0004] In general applications, the circuit requires a stable voltage to work properly and has a relatively high requirement for voltage stability. Due to the instability of the input voltage, especially in battery-powered application scenarios, the battery voltage may be higher or lower than the system voltage. To make the circuit work properly, this requires the power conversion circuit to be able to step down and step up voltages to meet the circuit usage requirements. Especially in the control circuit, to meet the functional requirements, power supplies with different voltage levels are needed, and a stable power supply voltage plays a crucial role in enabling the circuit to work stably.

[0005] The application of buck-boost power supply technology is extensive, including but not limited to outdoor power supplies, fast charging, mobile power supplies, outdoor energy storage, industrial control, communication and other fields. For example, in the field of outdoor power supplies, a power supply using efficient buck-boost technology can maintain a stable output voltage under different load conditions, solve the power loss problem, and at the same time support the fast charging function, providing users with a more convenient and efficient energy solution.

[0006] In addition, buck-boost power supply technology is also widely used in the field of LED lighting to provide stable voltage and current for LED lamps, extend the lamp life, and improve brightness and energy efficiency. Through the integrated chip design and the ability to automatically adjust the output voltage, buck-boost power supply technology realizes efficient and stable power management, is widely used in multiple fields, and improves the performance of equipment and the user experience.

[0007] However, existing solutions only have a single boost or buck function, and they work unstably or cannot work properly when the input voltage is close to the output voltage. Moreover, dedicated buck-boost DC-DC power management chips rely on imports, which are costly and not suitable for low-cost applications or domestic production requirements. At the same time, the peripheral circuit is complex, requires a power switching tube to cooperate as a driving output, and has relatively high requirements for the technical level of designers. Summary of the Invention

[0008] Therefore, an embodiment of the present invention provides an automatic buck-boost control circuit based on a DCDC control chip to solve the technical problems of the existing technology having only a single boost / buck function and a complex and costly peripheral circuit.

[0009] To achieve the above object, the embodiment of the present invention provides the following technical solutions:

[0010] According to the first aspect of the embodiment of the present invention, an automatic buck-boost control circuit based on a DCDC control chip is provided. The automatic buck-boost control circuit is composed of a DCDC control chip, a filter circuit, an energy storage circuit, a buck-boost circuit, and a voltage feedback circuit, and specifically includes:

[0011] The DCDC control chip is respectively connected to the filter circuit, the energy storage circuit, and the buck-boost circuit. The buck-boost circuit is connected to the voltage feedback circuit. The voltage feedback circuit is a voltage dividing circuit for outputting a stable voltage;

[0012] By repeating the charging and discharging process of the energy storage circuit and combining the voltage feedback circuit to control the PWM output duty cycle of the DCDC chip, the relationship between the output voltage and the input voltage is controlled so that a stable output voltage is obtained across the output capacitor of the buck-boost circuit.

[0013] Further, the filter circuit is composed of capacitors and specifically includes:

[0014] One end of the filter capacitor C5 is connected to both the 9-15V voltage and the filter capacitor C4 at the same time. The other end of C5 is grounded. The other end of the filter capacitor C4 is connected to the grounded end of the filter capacitor C5 and grounded at the same time. The filter capacitor C4 is also connected to the inductor L1, the 4th and 5th pins of the DCDC control chip, and the other end of the filter capacitor C4 is connected to the 2nd pin of the DCDC control chip.

[0015] Further, the energy storage circuit is composed of an inductor and a diode and specifically includes:

[0016] Pin 4 and pin 5 of the DCDC control chip are connected to one end of the inductor L1 at the same time. The other end of the inductor L1 is connected to pin 1 of the DCDC control chip. The inductor L1 is connected to the capacitor C1. One end of the capacitor C1 is reconnected to the inductor L2 and the cathode of the diode D1. The anode of the diode D1 is grounded. The other end of the inductor L2 is connected to the buck-boost circuit.

[0017] Further, the buck-boost circuit consists of two capacitors. One ends of the capacitor C3 and the capacitor C2 are respectively connected to the inductor L2 and are also connected to the 12V voltage at the same time. The other ends of the capacitor C3 and the capacitor C2 are respectively connected to the GND node and the voltage feedback circuit.

[0018] Further, the voltage feedback circuit is a voltage division circuit, specifically including:

[0019] The voltage feedback circuit is composed of the resistor R1 and the resistor R2 connected in series. One end of the resistor R1 is connected to the 12V voltage. The other end of the resistor R2 is respectively connected to the capacitor C2, the capacitor C3, the GND node and the anode of the diode. The middle node of the resistor R1 and the resistor R2 is connected to pin 3 of the DCDC control chip.

[0020] Further, pin 6 of the DCDC control chip is an idle pin.

[0021] Further, when the switch is closed, the output voltage passes through the inductor L1, and the current increases linearly while the inductor L1 stores energy. When the switch is opened, the discharge current of the inductor L1 flows through the capacitor C1 to the inductor L2 to store energy for the inductor L2. The inductor L2 charges the capacitor C2 and the capacitor C3. When the inductor L2 releases energy, it charges the capacitor C2 and the capacitor C3 through the freewheeling diode D1, increasing the voltage across the capacitor C2 and the capacitor C3.

[0022] Further, when the voltage output by the voltage division circuit of the output voltage is higher than the preset threshold, the DCDC control chip reduces the duty cycle of the switch. When the voltage output by the voltage division circuit of the output voltage is lower than the preset threshold, the DCDC control chip increases the duty cycle of the switch to adjust the output voltage;

[0023] Among them, the preset threshold is 0.6V.

[0024] The embodiments of the present invention have the following advantages:

[0025] In the embodiment of the present invention, an automatic buck-boost circuit is realized by a power control chip. By continuously repeating the charging and discharging processes and combining with a voltage feedback circuit, the control chip adjusts the PWM output duty cycle of the switch to control the relationship between the output voltage and the input voltage, and a stable output voltage is obtained across the output capacitor. The embodiment of the present invention has a wider input voltage range, where the input voltage can be higher or lower than the output voltage. And when the input voltage fluctuates between being higher and lower than the output voltage, there is no switching jitter in the output voltage, and a stable voltage can be continuously output, which is suitable for battery-powered application scenarios. The circuit is simple, small, low-cost, saves PCB area, works stably and reliably, and has a low ripple. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained according to the provided drawings.

[0027] The structures, ratios, sizes, etc. shown in this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention.

[0028] Figure 1 It is a schematic diagram of the logic structure of an automatic buck-boost control circuit based on a DCDC control chip provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the circuit principle of an automatic buck-boost control circuit based on a DCDC control chip provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following specific embodiments illustrate the implementation manners of the present invention. Those who are familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention.

[0031] The buck-boost power supply technology is a DC-DC conversion circuit that can automatically adjust the output voltage to be higher or lower than the input voltage. It combines the advantages of buck and boost circuits, and automatically achieves voltage stabilization according to the input voltage and load requirements to output the required voltage.

[0032] The core of this technology lies in the power controller chip, which integrates multiple components such as the control circuit and protection circuit into a single chip, simplifying the circuit design. At the same time, the buck-boost chip can automatically adjust the output voltage according to the input voltage and load requirements, ensuring a stable output voltage under different conditions, and solving the power loss problem caused by the separate design of traditional boost and buck circuits.

[0033] In general applications, the circuit requires a stable voltage to work properly and has relatively high requirements for voltage stability. Due to the instability of the input voltage, especially in battery-powered application scenarios, the battery voltage may be higher or lower than the system voltage. To make the circuit work properly, this requires the power conversion circuit to be able to step down and step up voltages to meet the circuit usage requirements. Especially in the control circuit, to meet the functional requirements, power supplies with different voltage levels are needed, and a stable power supply voltage plays a crucial role in achieving stable circuit operation.

[0034] The buck-boost power supply technology has a wide range of applications, including but not limited to outdoor power supplies, fast charging, mobile power supplies, outdoor energy storage, industrial control, communication and other fields. For example, in the field of outdoor power supplies, a power supply using efficient buck-boost technology can maintain a stable output voltage under different load conditions, solve the power loss problem, and at the same time support the fast charging function, providing users with a more convenient and efficient energy solution.

[0035] In addition, the buck-boost power supply technology is also widely used in the field of LED lighting, providing stable voltage and current for LED lamps, extending the lamp life, and improving brightness and energy efficiency. Through the integrated chip design and the ability to automatically adjust the output voltage, the buck-boost power supply technology realizes efficient and stable power management, is widely used in multiple fields, and improves the performance of equipment and the user experience.

[0036] However, existing solutions only have a single boost or buck function, work unstably or cannot work properly when the input voltage and output voltage are close, and the dedicated buck-boost DC-DC power management chips rely on imports, with high costs, are not suitable for low-cost applications nor for domestic production requirements. At the same time, the peripheral circuit is complex, requires a power switch tube to cooperate as the drive output, and has relatively high requirements for the technical level of designers.

[0037] To solve the above technical problems of the existing buck-boost power supply technology, which only has a single boost / buck function and a complex and costly peripheral circuit.

[0038] Reference Figure 1 , an embodiment of the present invention discloses an automatic buck-boost control circuit based on a DCDC control chip. The automatic buck-boost control circuit is composed of a DCDC control chip, a filter circuit, an energy storage circuit, a buck-boost circuit, and a voltage feedback circuit, and specifically includes:

[0039] The DCDC control chip is respectively connected to the filter circuit, the energy storage circuit, and the buck-boost circuit. The buck-boost circuit is connected to the voltage feedback circuit. The voltage feedback circuit is a voltage dividing circuit for outputting a stable voltage;

[0040] By repeating the charging and discharging process of the energy storage circuit and combining the voltage feedback circuit to control the PWM output duty cycle of the DCDC chip, the relationship between the output voltage and the input voltage is controlled so that a stable output voltage is obtained across the output capacitor of the buck-boost circuit.

[0041] Further, reference Figure 2 , the filter circuit is composed of capacitors and specifically includes: one end of the filter capacitor C5 is simultaneously connected to the 9-15V voltage and the filter capacitor C4. The other end of C5 is grounded. The other end of the filter capacitor C4 is simultaneously connected to the grounded end of the filter capacitor C5 and grounded. The filter capacitor C4 is also connected to the inductor L1, the 4th and 5th pins of the DCDC control chip, and the other end of the filter capacitor C4 is connected to the 2nd pin of the DCDC control chip.

[0042] Further, reference Figure 2 , the energy storage circuit is composed of an inductor and a diode and specifically includes: the 4th and 5th pins of the DCDC control chip are simultaneously connected to one end of the inductor L1. The other end of the inductor L1 is connected to the 1st pin of the DCDC control chip. The inductor L1 is connected to the capacitor C1. One end of the capacitor C1 is again connected to the inductor L2 and the cathode of the diode D1. The anode of the diode D1 is grounded. The other end of the inductor L2 is connected to the buck-boost circuit.

[0043] Further, reference Figure 2 , the buck-boost circuit is composed of two capacitors. One ends of the capacitor C3 and the capacitor C2 are respectively connected to the inductor L2 and are also connected to the 12V voltage. The other ends of the capacitor C3 and the capacitor C2 are respectively connected to the GND node and the voltage feedback circuit.

[0044] Further, reference Figure 2, the voltage feedback circuit is a voltage division circuit, specifically including: the voltage feedback circuit is composed of a resistor R1 and a resistor R2 connected in series. One end of the resistor R1 is connected to the 12V voltage, and the other end of the resistor R2 is respectively connected to the capacitor C2, the capacitor C3, the GND node and the anode of the diode. The middle node of the resistor R1 and the resistor R2 is connected to the 3rd pin of the DCDC control chip.

[0045] Further, referring to Figure 2 , the 6th pin of the DCDC control chip is an idle pin.

[0046] As Figure 2 , when an external power supply voltage is applied to the circuit input terminal, the circuit starts to work. The internal switch circuit of the power control chip U1 passes through the 1st pin. When the 1st pin of the power chip U1 is pulled low, the inductor L1 starts to store energy.

[0047] Referring to Figure 2 , when the switch is closed, the output voltage passes through the inductor L1, and the current increases linearly while the inductor L1 stores energy; when the switch is opened, the discharge current of the inductor L1 flows through the capacitor C1 to the inductor L2 to store energy for the inductor L2. The inductor L2 charges the capacitors C2 and C3. When the inductor L2 releases energy, it charges the capacitors C2 and C3 through the freewheeling diode D1, causing the voltage across the capacitors C2 and C3 to increase.

[0048] Please refer to Figure 2 , the circuit is composed of a DC-DC control chip U1, inductors L1 and L2, capacitors C1, C2, C3, C4, and C5, a diode D1, and resistors R1 and R2.

[0049] The 4th and 5th pins of U1 in the circuit are connected together and marked as node A. Node A is the positive pole of the power input. The 2nd pin of U1 is grounded and marked as node GND. Node GND is the common ground of the circuit. The 1st pin of U1 is marked as node C. The 3rd pin of U1 is grounded and marked as node D. The two ends of capacitor C4 in the circuit are respectively connected to node A and node GND. The two ends of capacitor C5 are respectively connected to node A and node GND. One end of inductor L1 is connected to node A, and the other end of inductor L1 is connected to node C. One end of capacitor C1 is connected to node C, and the other end of capacitor C1 is marked as node E. The cathode of diode D1 is connected to node E, and the anode of diode D1 is connected to node GND. One end of inductor L2 is connected to node E, and the other end of inductor L2 is marked as node F. One end of capacitor C3 is connected to node F, and the other end of C3 is connected to node GND. One end of capacitor C2 is connected to node F, and the other end of C2 is connected to node GND. Resistors R1 and R2 form a voltage feedback circuit. One end of resistor R1 is connected to node F, the other end of resistor R1 is connected to node D. One end of resistor R2 is connected to node D, and the other end of resistor R1 is connected to node GND. The 6th pin of U1 is an idle pin and is not connected to anything.

[0050] Further, referring to Figure 2 , when the output voltage outputs a voltage higher than the preset threshold through the voltage dividing circuit, the DCDC control chip reduces the switching duty cycle; when the output voltage outputs a voltage lower than the preset threshold through the voltage dividing circuit, the DCDC control chip increases the switching duty cycle to adjust the output voltage.

[0051] Wherein, the preset threshold is 0.6V.

[0052] In the embodiment of the present invention, the inductor stores and releases energy during the switching cycle, and the output voltage has no switching fluctuations. The capacitors connected in series in the circuit play a role in energy transfer in the periodically switched circuit. The circuit design is ingenious, with low power loss and high efficiency. Through a high switching frequency, a smaller inductance can be used, reducing the volume of the inductor, and thus further reducing the volume of the PCB.

[0053] Although the present invention has been described in detail above with general descriptions and specific embodiments, on the basis of the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An automatic buck-boost control circuit based on a DCDC control chip, characterized in that, The automatic buck-boost control circuit consists of a DCDC control chip, a filter circuit, an energy storage circuit, a buck-boost circuit, and a voltage feedback circuit, and specifically includes: The DCDC control chip is respectively connected to the filter circuit, the energy storage circuit, and the buck-boost circuit. The buck-boost circuit is connected to the voltage feedback circuit. The voltage feedback circuit is a voltage dividing circuit for outputting a stable voltage. By repeating the charging and discharging process of the energy storage circuit and combining with the voltage feedback circuit to control the PWM output duty cycle of the DCDC chip, the relationship between the output voltage and the input voltage is controlled so that a stable output voltage is obtained across the output capacitor of the buck-boost circuit.

2. The automatic buck-boost control circuit based on a DCDC control chip according to claim 1, wherein The filter circuit is composed of capacitors and specifically includes: One end of the filter capacitor C5 is connected to both the 9 - 15V voltage and the filter capacitor C4 simultaneously. The other end of C5 is grounded. The other end of the filter capacitor C4 is connected to the grounded end of the filter capacitor C5 and is grounded. The filter capacitor C4 is also connected to the inductor L1, pins 4 and 5 of the DCDC control chip, and the other end of the filter capacitor C4 is connected to pin 2 of the DCDC control chip.

3. The automatic buck-boost control circuit based on a DCDC control chip according to claim 2, wherein The energy storage circuit is composed of an inductor and a diode and specifically includes: Pins 4 and 5 of the DCDC control chip are connected to one end of the inductor L1 simultaneously. The other end of the inductor L1 is connected to pin 1 of the DCDC control chip. The inductor L1 is connected to the capacitor C1. One end of the capacitor C1 is connected to the inductor L2 and the cathode of the diode D1 again. The anode of the diode D1 is grounded. The other end of the inductor L2 is connected to the buck-boost circuit.

4. The automatic buck-boost control circuit based on a DCDC control chip according to claim 3, wherein, The buck-boost circuit consists of two capacitors. One ends of the capacitor C3 and the capacitor C2 are respectively connected to the inductor L2 and are also connected to the 12V voltage. The other ends of the capacitor C3 and the capacitor C2 are respectively connected to the GND node and the voltage feedback circuit.

5. The automatic buck-boost control circuit based on a DCDC control chip according to claim 4, characterized in that, The voltage feedback circuit is a voltage dividing circuit and specifically includes: The voltage feedback circuit is composed of the resistor R1 and the resistor R2 connected in series. One end of the resistor R1 is connected to the 12V voltage. The other end of the resistor R2 is connected to the capacitor C2, the capacitor C3, the GND node, and the anode of the diode respectively. The middle node of the resistor R1 and the resistor R2 is connected to pin 3 of the DCDC control chip.

6. The automatic buck-boost control circuit based on a DCDC control chip according to claim 5, wherein Pin 6 of the DCDC control chip is an idle pin.

7. The automatic buck-boost control circuit based on a DCDC control chip according to claim 6, characterized in that, When the switch is closed, the output voltage passes through the inductor L1, and the current increases linearly while the inductor L1 stores energy. When the switch is opened, the discharge current of the inductor L1 flows through the capacitor C1 to the inductor L2 to store energy for the inductor L2. The inductor L2 charges the capacitors C2 and C3. When the inductor L2 releases energy, it charges the capacitors C2 and C3 through the freewheeling diode D1, causing the voltage across the capacitors C2 and C3 to increase.

8. The automatic buck-boost control circuit based on a DCDC control chip according to claim 7, characterized in that, When the output voltage output by the voltage dividing circuit is higher than the preset threshold voltage, the DCDC control chip reduces the switch duty cycle. When the output voltage output by the voltage dividing circuit is lower than the preset threshold voltage, the DCDC control chip increases the switch duty cycle to adjust the output voltage. Among them, the preset threshold is 0.6V.

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