DC-DC conversion circuit and electronic equipment

Abstract

A DC-DC conversion circuit and an electronic device, the DC-DC conversion circuit comprising: a switching control circuit for outputting a control signal for controlling the switching circuit; the switching circuit is connected with the direct current input end and the switching control circuit and used for being switched on or switched off based on the control signal; the step-down circuit is connected with the switching circuit and is used for converting the input voltage of the direct current input end into output voltage based on turn-on and turn-off of the switching circuit; the charging circuit is connected with the step-down circuit and is used for charging a bus capacitor in the charging circuit based on the energy of the inductance follow current stage of the step-down circuit, and the bus capacitor can be used for supplying power to the switch control circuit and / or the feedback circuit; and the feedback circuit is connected with the step-down circuit and is used for sampling an output signal of the step-down circuit and feeding back the sampled signal to the switch control circuit. The direct current-direct current conversion circuit can solve the problems of high price, high standby power consumption and the like of an integrated chip scheme adopted by the existing direct current-direct current circuit.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and more specifically to a DC-DC conversion circuit and electronic device. Background Technology

[0002] With the continuous development of power electronics technology, the types and quantities of portable electronic products are constantly increasing, and the demand for wide-input, high-efficiency DC-DC converter topologies for power supply systems of portable electronic devices is becoming increasingly strong. In the field of portable power supply systems such as power adapters, LED drivers, and smart mobile terminals, current buck converters are difficult to meet the power efficiency and cost requirements of these devices due to their low efficiency, narrow input voltage range, high standby power consumption, and high price. Summary of the Invention

[0003] This application is made to address at least one of the aforementioned problems. According to one aspect of this application, a DC-DC converter circuit is provided, the DC-DC converter circuit comprising: A switch control circuit, used to output control signals to control the switch circuit; The switching circuit is connected to the DC input terminal and the switching control circuit, and is used to turn on or off based on the control signal. A step-down circuit, connected to the switching circuit, is used to convert the input voltage at the DC input terminal into an output voltage based on the on and off states of the switching circuit. A charging circuit, connected to the step-down circuit, is used to charge the bus capacitor in the charging circuit based on the energy of the inductor freewheeling phase of the step-down circuit. The bus capacitor can be used to power the switch control circuit and / or feedback circuit. The feedback circuit is connected to the step-down circuit and is used to sample the output signal of the step-down circuit and feed the sampled signal back to the switch control circuit.

[0004] In one embodiment of this application, the charging circuit is a bootstrap capacitor charging circuit.

[0005] In one embodiment of this application, the bootstrap capacitor charging circuit includes: The first capacitor is the bus capacitor. The first terminal of the first capacitor is connected to the step-down circuit and the switch control circuit, and the second terminal of the first capacitor is grounded. The second capacitor has its first terminal connected to the first terminal of the first capacitor, and its second terminal grounded. The first diode has its cathode connected to the first terminal of the first capacitor and its anode connected to the step-down circuit. The first Zener diode has its cathode connected to the first terminal of the second capacitor, and its anode grounded.

[0006] In one embodiment of this application, the feedback circuit includes a voltage feedback circuit, which samples the voltage value of the output signal of the buck circuit and feeds back the voltage sampling result to the switch control circuit, so that the switch control circuit outputs a control signal to control the switch circuit based on the voltage sampling result.

[0007] In one embodiment of this application, the voltage feedback circuit includes: The second Zener diode has its cathode connected to the switch control circuit and its anode connected to the first terminal of the second resistor. The second resistor, the second end of the second resistor is connected to the first end of the third capacitor and the base of the first transistor; The third capacitor has its second terminal grounded. The first transistor has its collector connected to the switch control circuit and its emitter grounded.

[0008] In one embodiment of this application, the feedback circuit further includes a current feedback circuit, which samples the current value of the output signal and feeds the current sampling result back to the switch control circuit, so that the switch control circuit outputs a control signal to control the switch circuit based on the voltage sampling result and the current sampling result.

[0009] In one embodiment of this application, the current feedback circuit is connected to the switch control circuit, the current feedback circuit is also used for overcurrent protection, and the bus capacitor can be used to power the current feedback circuit.

[0010] In one embodiment of this application, the current feedback circuit includes: A first resistor, the first end of which is connected to the step-down circuit, and the second end of which is connected to the first end of a third resistor; The third resistor, the second end of which is connected to the first end of the fourth capacitor and the base of the second transistor; The second terminal of the fourth capacitor is grounded; The second transistor has its emitter grounded and its collector connected to the switch control circuit.

[0011] In one embodiment of this application, the DC-DC conversion circuit further includes: A soft-start circuit, connected to the switch control circuit and the feedback circuit, is used to suppress inrush current and voltage overshoot in the DC-DC conversion circuit.

[0012] In one embodiment of this application, the soft-start circuit includes: The third transistor, the base of which is connected to the feedback circuit, and the collector of which is grounded; The fifth capacitor has its first terminal connected to the second terminal of the fourth resistor and the positive input terminal of the comparator, and its second terminal grounded. The fourth resistor, the first end of which is connected to the first end of the fifth resistor; The fifth resistor, the second end of which is connected to the output of the comparator; The comparator has its negative input connected to a reference signal.

[0013] In one embodiment of this application, the switch control circuit is a totem pole topology switch control circuit.

[0014] In one embodiment of this application, the totem pole topology switch control circuit includes: The fourth transistor has its base connected to the feedback circuit, its collector connected to the first terminal of the sixth resistor, and its emitter connected to the collector of the fifth transistor. The base of the fifth transistor is connected to the base of the fourth transistor, and the emitter of the fifth transistor is grounded. The sixth resistor has its second end connected to the cathode of the third Zener diode; The anode of the third Zener diode is connected to the base of the sixth transistor; The collector of the sixth transistor is connected to the second terminal of the seventh resistor and the cathode of the fourth Zener diode, and the emitter of the sixth transistor is grounded. The seventh resistor, the first end of the seventh resistor is connected to the base of the seventh transistor; The collector of the seventh transistor is connected to the first terminal of the sixth resistor, and the emitter of the seventh transistor is connected to the charging circuit. The fourth Zener diode has its anode grounded.

[0015] In one embodiment of this application, the switching circuit is a MOS switching circuit.

[0016] In one embodiment of this application, the MOS switching circuit includes: The MOS transistor has its gate connected to the first terminal of the sixth capacitor, its source connected to the second terminal of the eighth resistor, and its drain connected to the DC input terminal. The second terminal of the sixth capacitor is connected to the second terminal of the eighth resistor; The eighth resistor, the first end of which is connected to the first end of the ninth resistor and the first end of the sixth capacitor; The ninth resistor, the second end of which is connected to the switch control circuit.

[0017] In one embodiment of this application, the step-down circuit includes: An inductor, wherein the first end of the inductor is connected to the cathode of the second diode, and the second end of the inductor is connected to the first end of the seventh capacitor; The second diode, with its anode grounded; The seventh capacitor has its second terminal grounded. The eighth capacitor has its first terminal connected to the first terminal of the seventh capacitor, and its second terminal grounded. The tenth resistor has its first end connected to the first end of the eighth capacitor and its second end connected to the anode of the light-emitting element. The light-emitting element has its cathode grounded.

[0018] In one embodiment of this application, the DC-DC conversion circuit further includes: A voltage divider and current limiting circuit is connected to the switch control circuit, the charging circuit, and the feedback circuit. The DC input terminal precharges the bus capacitor via the voltage divider and current limiting circuit.

[0019] In one embodiment of this application, the voltage divider and current limiting circuit includes: The eleventh resistor has its first end connected to the DC input terminal and its second end connected to the first end of the twelfth resistor. The twelfth resistor has its second end connected to the switch control circuit, the charging circuit, and the feedback circuit.

[0020] According to another aspect of this application, an electronic device is also provided, the electronic device including the above-described DC-DC conversion circuit.

[0021] The DC-DC conversion circuit and electronic device according to the embodiments of this application can solve the problems of high cost and high standby power consumption of existing DC-DC circuits using integrated chip solutions. They have the advantages of simple circuit, high reliability, low cost, wide input voltage range, no need for additional heat dissipation design, low cost, and high efficiency. Attached Figure Description

[0022] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0023] Figure 1 A schematic block diagram of a DC-DC conversion circuit according to an embodiment of this application is shown.

[0024] Figure 2 An exemplary circuit diagram of a charging circuit in a DC-DC conversion circuit according to an embodiment of this application is shown.

[0025] Figure 3 An exemplary circuit diagram of a soft-start circuit in a DC-DC converter circuit according to an embodiment of this application is shown.

[0026] Figure 4 An exemplary circuit diagram of a switch control circuit in a DC-DC converter circuit according to an embodiment of this application is shown.

[0027] Figure 5 An exemplary circuit diagram of a buck converter circuit in a DC-DC converter circuit according to an embodiment of this application is shown.

[0028] Figure 6 An exemplary circuit diagram of a DC-DC conversion circuit according to an embodiment of this application is shown.

[0029] Figure 7 A system architecture diagram of a DC-DC conversion circuit according to an embodiment of this application is shown.

[0030] Figure 8 An exemplary measured waveform diagram of a DC-DC conversion circuit according to an embodiment of this application is shown. Detailed Implementation

[0031] Figure 1 A schematic block diagram of a DC-DC converter circuit 1 according to an embodiment of this application is shown. Figure 1As shown, the DC-DC converter circuit 1 includes a switch control circuit 11, a switch circuit 12, a buck converter 13, a charging circuit 14, and a feedback circuit 15. The switch control circuit 11 outputs a control signal to control the switch circuit 12. The switch circuit 12 is connected to the DC input terminal and the switch control circuit 11, and is used to turn the DC input terminal on or off based on the control signal. The buck converter 13 is connected to the switch circuit 12 and is used to convert the input voltage of the DC input terminal into an output voltage based on the on / off state of the switch circuit 12. The charging circuit 14 is connected to the buck converter 13 and is used to charge the bus capacitor in the charging circuit 14 based on the energy from the freewheeling phase of the buck converter 13. The bus capacitor can be used to power the switch control circuit 11 and / or the feedback circuit 15. The feedback circuit 15 is connected to the buck converter 13 and is used to sample the output signal of the buck converter 13 and feed the sampled signal back to the switch control circuit 11.

[0032] In the embodiments of this application, the DC-DC converter circuit 1 utilizes the output energy during the inductor freewheeling phase to charge the bus capacitor in the charging circuit 14 connected to the buck circuit 13. This allows the bus capacitor to power the front-end circuits such as the switch control circuit 11, significantly reducing power consumption and improving output efficiency. Specifically, during the turn-on phase of the switch in the switch circuit 12, the input voltage at the DC input terminal is applied to the inductor in the buck circuit 13 through the switch in the switch circuit 12. The inductor stores energy and simultaneously supplies power to the load. During the turn-off phase of the switch in the switch circuit 12, i.e., the freewheeling phase, the inductor generates a reverse electromotive force due to its resistance to sudden current changes. This energy is then released to the load through a freewheeling element (such as a diode), and the output terminal maintains a stable voltage. In conventional DC-DC converter circuits 1, the front-end circuits (such as the switch control circuit 11 and the feedback circuit 15) used to generate pulse width modulation (PWM) signals are powered by the input side or by an independent auxiliary power supply, resulting in losses. The DC-DC conversion circuit 1 provided in this application includes a charging circuit 14 connected to the step-down circuit 13. During the turn-off phase of the switching transistor in the switching circuit 12, which is also the freewheeling phase, the inductor releases energy to the load while simultaneously charging the bus capacitor in the charging circuit 14. This is equivalent to storing the remaining energy from the freewheeling phase and reusing it. The power supply of the front-end circuit no longer needs to be drawn from the input side or supplied by an auxiliary power supply, but is instead provided by the charged bus capacitor. This design concept of a floating circuit greatly reduces the power consumption of the product and improves the output efficiency of the product.

[0033] Furthermore, since the bus capacitor is charged through the inductor freewheeling stage, and the energy of the inductor freewheeling comes from the residual energy of the input voltage after conversion by the switching transistor, the energy of the freewheeling stage can replenish the charge of the bus capacitor regardless of the input voltage level, ensuring the stability of the supply voltage of the preceding circuit. This allows the entire circuit to operate normally over a wide input range.

[0034] Furthermore, since no auxiliary power supply is required, the circuit structure is simplified, the number of circuit components is reduced, material costs are lowered, circuit board layout is simplified, and the complexity of production and debugging is reduced, further reducing the overall cost. Moreover, common-mode interference between the auxiliary power supply and the main circuit is avoided, reducing control signal distortion and improving the circuit's stable operation in electromagnetic environments. Furthermore, the reduced number of circuit components reduces the likelihood of failures, thereby further improving circuit reliability.

[0035] Furthermore, the improved product output efficiency, i.e., high energy utilization, means lower circuit losses. This reduces the losses of core heat-generating components such as switching transistors and inductors, preventing their operating temperatures from becoming too high. Consequently, the circuit as a whole does not require additional heat sinks or other heat dissipation designs, further simplifying the structure and reducing costs.

[0036] Therefore, the DC-DC converter circuit 1 according to the embodiments of this application can solve the problems of high cost and high standby power consumption of existing DC-DC circuits using integrated chip solutions. It has the advantages of simple circuit, high reliability, low cost, wide input voltage range, no need for additional heat dissipation design, low cost, and high efficiency.

[0037] In one embodiment of this application, the charging circuit 14 described above is a bootstrap capacitor charging circuit. Exemplarily, this bootstrap capacitor charging circuit may include a first capacitor, a second capacitor, a first diode, and a first Zener diode. The first capacitor is the aforementioned bus capacitor, with its first terminal connected to the step-down circuit 13 and the switch control circuit 11, and its second terminal grounded. The first terminal of the second capacitor is connected to the first terminal of the first capacitor, and its second terminal is grounded. The cathode of the first diode is connected to the first terminal of the first capacitor, and the anode of the first diode is connected to the step-down circuit 13. The cathode of the first Zener diode is connected to the first terminal of the second capacitor, and the anode of the first Zener diode is grounded.

[0038] In this example, the bootstrap capacitor charging circuit can store energy through the first capacitor, and the second capacitor can be used to filter out high-frequency ripple in the drive circuit, avoiding unstable switching of the switching transistor due to gate voltage fluctuations. Furthermore, the parallel connection of the two capacitors allows for rapid energy release, ensuring fast and reliable switching of the switching transistor in the switching circuit 12. The first diode is connected to the buck circuit 13, enabling efficient charging of the first capacitor during the inductor freewheeling phase, and the first Zener diode maintains voltage stability.

[0039] Figure 2 An exemplary circuit diagram of this bootstrap capacitor charging circuit is shown. Figure 2 In the diagram, the first capacitor is shown as C12, the second capacitor as C10, the first diode as D6, and the first Zener diode as D8. C12 and C10 can be electrolytic capacitors, and D8 can be a Zener diode. Electrolytic capacitors have large capacitance, which can meet the requirements of large gate charge, and are low in cost. Zener diode D8 can achieve precise clamping, prevent overvoltage during charging, and suppress switching noise. The unidirectional conductivity of diode D6 can prevent the bus capacitor from discharging backwards to the output terminal. It should be understood that... Figure 2 The circuit diagram shown is only an example. In other examples, the charging circuit 14 can also be other structures, as long as it can achieve the functions described above.

[0040] In one embodiment of this application, the feedback circuit 15 includes a voltage feedback circuit, which samples the voltage value of the output signal of the buck circuit 13 and feeds the voltage sampling result back to the switch control circuit 11, so that the switch control circuit 11 outputs a control signal to control the switch circuit 12 based on the voltage sampling result. In this embodiment, the feedback circuit 15 is a voltage loop feedback circuit, which samples the output voltage, compares it with a reference voltage to obtain an error signal, adjusts the PWM duty cycle according to the error signal, and finally stabilizes the output voltage at the target value.

[0041] Furthermore, the feedback circuit 15 may also include a current feedback circuit. This current feedback circuit samples the current value of the output signal and feeds the current sampling result back to the switch control circuit 11. The switch control circuit 11 then outputs a control signal to the switch circuit 12 based on the aforementioned voltage and current sampling results. In this embodiment, in addition to sampling the output voltage, the output current is also sampled. When the current exceeds a safety threshold, the switch can be immediately turned off to prevent circuit damage due to overcurrent, thus providing overcurrent protection. That is, the feedback circuit 15 is a voltage and current dual-loop feedback circuit. It samples the output voltage to obtain a feedback signal, forming a closed loop with the given voltage. It samples the inductor current to obtain a current feedback signal, forming an inner current loop control with the given current. For example, when the load suddenly increases, the output voltage will briefly drop. The voltage loop first detects the error and increases the duty cycle; simultaneously, the inductor current rises rapidly, and the current loop limits its peak value, thus avoiding overcurrent and accelerating the adjustment process. Therefore, the voltage and current dual-loop feedback circuit can ensure stable output voltage while improving response speed and safety. Moreover, the current loop directly controls the inductor current and can track load changes in real time. Even if the load fluctuates within a wide range, the circuit can adjust quickly to ensure stable output, thereby improving the load-carrying capacity of the entire circuit.

[0042] For example, the voltage feedback circuit described above may include: a second Zener diode, a second resistor, a third capacitor, and a first transistor. The cathode of the second Zener diode is connected to the switch control circuit 11, and the anode of the second Zener diode is connected to the first terminal of the second resistor; the second terminal of the second resistor is connected to the first terminal of the third capacitor and the base of the first transistor; the second terminal of the third capacitor is grounded; the collector of the first transistor is connected to the switch control circuit 11, and the emitter of the first transistor is grounded. An exemplary circuit diagram of the voltage feedback circuit is not shown separately here; please refer to the following description. Figure 6 To understand this voltage feedback circuit, please refer to the overall example circuit diagram of the described DC-DC conversion circuit 1. Figure 6 In the example shown, the second Zener diode is shown as D9, the second resistor as R20, the third capacitor as C15, and the first transistor as Q7. It should be understood that the voltage feedback circuit shown here is merely exemplary; in other examples, the voltage feedback circuit can have other structures, as long as it achieves the function described above.

[0043] In one embodiment of this application, the current feedback circuit is connected to the switch control circuit 11 and can also be used for overcurrent protection and other protective functions to ensure the safety and reliability of circuit operation. In the aforementioned voltage and current dual-loop feedback architecture example, the response speed of the inner current loop is much faster than that of the outer voltage loop. The current feedback circuit can intervene to regulate as soon as an abnormal current occurs, for example, by limiting the PWM duty cycle to reduce the current and prevent the fault from escalating. In one example, the aforementioned bus capacitor can also be used to power the current feedback circuit, thereby further improving energy utilization.

[0044] For example, the current feedback circuit may include a first resistor, a third resistor, a fourth capacitor, and a second transistor. The first terminal of the first resistor is connected to the step-down circuit 13, and the second terminal of the first resistor is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the first terminal of the fourth capacitor and the base of the second transistor. The second terminal of the fourth capacitor is grounded. The emitter of the second transistor is grounded, and the collector of the second transistor is connected to the switch control circuit 11. The first resistor samples the inductor current. By selecting different values ​​of the first resistor, the trigger threshold for overcurrent protection can be adjusted, making it more flexible for different scenarios. The third resistor provides signal voltage division and current limiting protection. The fourth capacitor filters high-frequency interference and smooths the sampled signal. The second transistor, as a switching element, can quickly trigger the switch and amplify the sampled signal, facilitating control execution based on the sampled signal. Overall, this structure is low-cost, flexible in design, and robust. An exemplary circuit diagram of the current feedback circuit is not shown separately here; please refer to the following text for more details. Figure 6 To understand this current feedback circuit, please refer to the overall example circuit diagram of the described DC-DC conversion circuit 1. Figure 6In the example shown, the first resistor is shown as R19, the third resistor as R21, the fourth capacitor as C13, and the second transistor as Q8. It should be understood that the current feedback circuit shown here is merely exemplary; in other examples, the current feedback circuit can have other structures, as long as it achieves the function described above.

[0045] In one embodiment of this application, the DC-DC conversion circuit 1 may further include a soft-start circuit (not included in...). Figure 1 As shown in the figure, Figure 6 (Example structure shown). The soft-start circuit is connected to the switch control circuit 11 and the feedback circuit 15 to suppress inrush current and / or voltage overshoot in the DC-DC converter circuit 1. The soft-start circuit can progressively control the duty cycle of the control switch, allowing the duty cycle to slowly increase from zero over time until it reaches the target value for stable operation. This causes the output voltage of the entire DC-DC converter circuit to slowly rise to the set value. Throughout the process, the inductor current and capacitor charging current are limited to a safe range, avoiding instantaneous surges.

[0046] For example, the soft-start circuit may include a third transistor, a fifth capacitor, a fourth resistor, a fifth resistor, and a comparator. The base of the third transistor is connected to the feedback circuit 15, and the collector of the third transistor is grounded. The first terminal of the fifth capacitor is connected to the second terminal of the fourth resistor and the positive input terminal of the comparator, and the second terminal of the fifth capacitor is grounded. The first terminal of the fourth resistor is connected to the first terminal of the fifth resistor. The second terminal of the fifth resistor is connected to the output terminal of the comparator. The negative input terminal of the comparator is connected to a reference signal. This soft-start circuit uses discrete components, resulting in low cost, strong anti-interference capabilities, and ease of debugging.

[0047] Figure 3 An exemplary circuit diagram of a soft-start circuit is shown. Figure 3 In the diagram, the aforementioned third transistor is shown as Q5, the aforementioned fifth capacitor as C25, the aforementioned fourth resistor as R25, the aforementioned fifth resistor as R2, and the aforementioned comparator as U1A. It should be understood that... Figure 3 The circuit diagram shown is for illustrative purposes only. In other examples, the soft-start circuit can have other structures, as long as they can achieve the functions described above.

[0048] In one embodiment of this application, the aforementioned switch control circuit 11 can be a totem pole topology switch control circuit. The totem pole topology switch control circuit can achieve bidirectional high-current output, making it adaptable to various loads ranging from low to high impedance. Furthermore, it features fast switching speed, low conduction loss, low output impedance, strong anti-interference capability, and a simple structure, low cost, and ease of integration.

[0049] For example, the totem pole topology switch control circuit may include: a fourth transistor, a fifth transistor, a sixth resistor, a third Zener diode, a sixth transistor, a seventh resistor, a seventh transistor, and a fourth Zener diode. Specifically, the base of the fourth transistor is connected to the feedback circuit 15; the collector of the fourth transistor is connected to the first terminal of the sixth resistor; the emitter of the fourth transistor is connected to the collector of the fifth transistor; the base of the fifth transistor is connected to the base of the fourth transistor; and the emitter of the fifth transistor is grounded. The second terminal of the sixth resistor is connected to the cathode of the third Zener diode; the anode of the third Zener diode is connected to the base of the sixth transistor; the collector of the sixth transistor is connected to the second terminal of the seventh resistor and the cathode of the fourth Zener diode; and the emitter of the sixth transistor is grounded. The first terminal of the seventh resistor is connected to the base of the seventh transistor; the collector of the seventh transistor is connected to the first terminal of the sixth resistor; and the emitter of the seventh transistor is connected to the charging circuit 14. The anode of the fourth Zener diode is grounded. The totem pole topology switch control circuit 11 of this structure includes multiple transistors, resistors and diodes, which has stronger driving capability, more reliable switching and stronger robustness.

[0050] Figure 4 An exemplary circuit diagram of the switch control circuit 11 is shown. Figure 4 In the diagram, the aforementioned fourth transistor is shown as Q2, the aforementioned fifth transistor as Q5, the aforementioned sixth resistor as R6, the aforementioned third Zener diode as D5, the aforementioned sixth transistor as Q6, the aforementioned seventh resistor as R8, the aforementioned seventh transistor as Q1, and the aforementioned fourth Zener diode as D7. It should be understood that... Figure 4 The circuit diagram shown is merely an example. In other examples, the switch control circuit 11 can also have other structures, as long as it can achieve the functions described above.

[0051] In one embodiment of this application, the aforementioned switching circuit 12 can be a MOS switching circuit. MOS switching circuits have advantages such as low conduction loss, high switching speed, easy driving, and high reliability, which are beneficial for achieving high efficiency, miniaturization, and integration of the DC-DC conversion circuit 1.

[0052] For example, the MOS switching circuit may include a MOS transistor, a sixth capacitor, an eighth resistor, and a ninth resistor. The gate of the MOS transistor is connected to the first terminal of the sixth capacitor, the source of the MOS transistor is connected to the second terminal of the eighth resistor, and the drain of the MOS transistor is connected to the DC input terminal. The second terminal of the sixth capacitor is connected to the second terminal of the eighth resistor. The first terminal of the eighth resistor is connected to the first terminal of the ninth resistor and the first terminal of the sixth capacitor. The second terminal of the ninth resistor is connected to the switch control circuit 11. This structure achieves efficient and reliable switching functionality with a minimal number of components. An exemplary circuit diagram of the switch circuit 12 is not shown separately here; please refer to the following description. Figure 6To understand the switching circuit 12, please refer to the overall example circuit diagram of the described DC-DC conversion circuit 1. Figure 6 In the example shown, the MOSFET is shown as Q3, the sixth capacitor as C2, the eighth resistor as R14, and the ninth resistor as R11. It should be understood that the switching circuit 12 shown here is merely exemplary; in other examples, the switching circuit 12 may have other structures, as long as they achieve the functions described above.

[0053] In one embodiment of this application, the aforementioned step-down circuit 13 may include an inductor, a second diode, a seventh capacitor, an eighth capacitor, a tenth resistor, and a light-emitting element. The first terminal of the inductor is connected to the cathode of the second diode, and the second terminal of the inductor is connected to the first terminal of the seventh capacitor; the anode of the second diode is grounded; the second terminal of the seventh capacitor is grounded; the first terminal of the eighth capacitor is connected to the first terminal of the seventh capacitor, and the second terminal of the eighth capacitor is grounded; the first terminal of the tenth resistor is connected to the first terminal of the eighth capacitor, and the second terminal of the tenth resistor is connected to the anode of the light-emitting element; the cathode of the light-emitting element is grounded. This step-down circuit 13 is composed of basic components, requiring no complex integrated chips, and can achieve efficient and stable step-down functionality.

[0054] Figure 5 An exemplary circuit diagram of the step-down circuit 13 is shown. Figure 5 In this diagram, the aforementioned inductor is shown as L2, the aforementioned second diode as D10, the aforementioned seventh capacitor as C11, the aforementioned eighth capacitor as C9, the aforementioned tenth resistor as R16, and the aforementioned light-emitting element as D11. It should be understood that... Figure 5 The circuit diagram shown is only an example. In other examples, the step-down circuit 13 can also be other structures, as long as it can achieve the function described above.

[0055] In one embodiment of this application, the DC-DC conversion circuit 1 further includes a voltage divider and current limiting circuit (not included in...). Figure 1 As shown in the figure, Figure 6 (Example structure is provided). The voltage divider and current limiting circuit connects the switch control circuit 11, the charging circuit 14, and the feedback circuit 15. The DC input terminal precharges the bus capacitor via the voltage divider and current limiting circuit, thereby suppressing the inrush current when the bus capacitor is powered on and playing a protective role.

[0056] For example, the voltage divider current limiting circuit may include an eleventh resistor and a twelfth resistor. The first terminal of the eleventh resistor is connected to the DC input terminal, and the second terminal of the eleventh resistor is connected to the first terminal of the twelfth resistor. The second terminal of the twelfth resistor is connected to the switch control circuit 11, the charging circuit 14, and the feedback circuit 15. In this example, the voltage divider current limiting circuit is implemented using two series resistors, which, compared to using a single current limiting resistor, can distribute power loss, reduce the risk of heat generation, and improve reliability. An exemplary circuit diagram of the voltage divider current limiting circuit is not shown separately here; please refer to the following description. Figure 6 To understand this voltage divider and current limiting circuit, please refer to the overall example circuit diagram of the described DC-DC converter circuit 1. Figure 6 In the example shown, the eleventh resistor is represented as R4, and the twelfth capacitor as R3. It should be understood that the voltage divider and current limiting circuit shown here is merely exemplary, and in other examples, the voltage divider and current limiting circuit can also have other structures, as long as they can achieve the functions described above.

[0057] The following is combined with Figure 6 The following describes a more specific exemplary circuit structure for the DC-DC conversion circuit obtained by combining these examples. It should be understood that this is merely exemplary, and other suitable structures may be used in other examples. Figure 6 As shown, this DC-DC conversion circuit provides a novel low-cost BUCK topology circuit, which includes, in sequence, a +VBUS DC input, a totem pole topology switch control circuit, a soft-start circuit, a MOS switch circuit, a bootstrap capacitor charging circuit, a BUCK step-down circuit, a voltage loop feedback circuit, and a current feedback circuit.

[0058] The +VBUS DC input is connected to the drain of Q3 (pin 2) and R4 (pin 1). Pin 2 of R4 is connected to pin 1 of R3. Pin 2 of R3 is connected to pin 2 of D8 and pin 1 of C12.

[0059] Furthermore, the MOS switching circuit includes a MOS transistor Q3, R11, R14, and C2; pin 1 of R11 is connected to pin 1 of C2, pin 1 of the gate of Q3, and pin 1 of R14, and pin 3 of Q3 is connected to pin 2 of R14 and C2.

[0060] Furthermore, the bootstrap capacitor charging circuit includes Zener diode D8, capacitor C10, electrolytic capacitor C12, and capacitor D6. Pin 2 of Zener diode D8 is connected to pin 2 of Zener diode D9, pin 1 of capacitor C10, pin 1 of capacitor C12, the cathode of pin 2 of D6, and the emitter of pin 2 of PNP transistor Q1. Pin 1 of Zener diode D8, pin 2 of capacitor C10, and pin 2 of capacitor C12 are connected to floating ground.

[0061] Furthermore, the BUCK step-down circuit includes a filter energy storage inductor L2, output filter capacitors C11 and C9, a freewheeling diode D10, resistor R16, and indicator light D11. Pin 1 of inductor L2 is connected to pin 1 of resistor R19 and the cathode of pin 2 of resistor D10. Pin 2 of inductor L2 is connected to the anode of pin 1 of resistor D6, and pin 1 of capacitors C11, C9, and R16. The anode of pin 1 of freewheeling diode D10 is connected to ground via capacitors C11, C9, pin 2 of D11, and the circuit itself. Pin 2 of resistor R16 is connected to pin 1 of indicator light D11.

[0062] Furthermore, the totem pole switch control circuit includes NPN transistor Q2, PNP transistor Q5, PNP transistor Q1, NPN transistor Q6, resistors R6 and R8, and Zener diodes D5 and D7. The base of pin 1 of Q2 is connected to the base of pin 1 of Q5 and pin 2 of R2. The collector of pin 3 of Q2 is connected to the collector of pin 3 of Q1 and pin 1 of R6. The emitter of pin 2 of Q2 is connected to the collector of pin 3 of Q5 and pin 2 of R11. Pin 2 of R6 is connected to pin 2 of Zener diode D5. Pin 1 of D5 is connected to the base of pin 1 of transistor Q6. The emitter of pin 2 of Q6 is connected to pin 1 of Zener diode D7. Pin 2 of D7 is connected to the emitter of pin 3 of transistor Q6 and pin 2 of R8. Pin 1 of R8 is connected to the base of pin 1 of transistor Q1.

[0063] Furthermore, the soft-start circuit includes a PNP transistor Q5, R25, C25, comparator U1A, and R2. The emitter of pin 2 of Q5 is connected to pin 2 of R25, pin 1 of C25, and pin 3 of U1A. The collector of pin 3 of Q5 is connected to pin 2 of C25 and pin 11 of U1A to floating ground. Pin 2 of U1A is connected to the Vout signal of the preceding circuit. Pin 1 of R25 is connected to pin 4 of U1A, pin 1 of R2, and the collector of pin 3 of Q2. Pin 2 of R2 is connected to pin 1 of U1A, and the base of pin 1 of Q2 and Q5.

[0064] Furthermore, the current feedback circuit includes R19, R21, C13, and NPN transistor Q8; pin 2 of R19 is connected to pin 1 of R21, pin 2 of R21 is connected to pin 1 of C13 and the base of pin 1 of Q8, pin 2 of C13 and the emitter of pin 2 of Q8 are connected to floating ground, and the collector of pin 3 of Q8 is connected to the base of Q2 and Q5.

[0065] Furthermore, the voltage loop feedback circuit (i.e., the voltage feedback circuit) includes a Zener diode D9, resistor R20, capacitor C15, and an NPN transistor Q7. Pin 1 of the Zener diode D9 is connected to pin 1 of resistor R20. Pin 2 of resistor R20 is connected to pin 1 of capacitor C15 and the base of pin 1 of transistor Q7. Pin 2 of transistor Q7 and capacitor C15 are connected to floating ground. Pin 3 of transistor Q7 is connected to the base of pin 1 of transistor Q5.

[0066] The circuit works as follows: When the mains power is normal, the +VBUS DC power converted from the mains power precharges the bus capacitor C12 through resistors R4 and R3. When the capacitor voltage reaches 15V, the base voltage of Q1, Ub = Uc - 0.7V, turns on the Zener diode D7, and pulls the base of transistor Q1 to a low level, turning on the PNP transistor Q1. At this time, the collector voltage of transistor Q1 is approximately 15V, which turns on the 12V Zener diode D5. At this time, the base voltage of Q6 is greater than 0.7V, the emitter is forward biased, and the collector is reverse biased, so transistor Q6 also turns on. At this time, the on / off state of transistor Q1 is controlled by transistor Q6. The power supply for the front-end circuit is provided by the bus capacitor C12. The front-end circuit generates a PWM signal to drive the switching transistor. At this time, the subsequent BUCK circuit starts working. During operation, it samples the output voltage of the converter and compares it with the regulated voltage of the Zener diode D9. The comparison result is used as the input for subsequent pulse width modulation. By adjusting the duty cycle of the output PWM waveform, it controls the conduction or cutoff of the switching transistor Q3 and the freewheeling diode D10. During operation, the inductor current is sampled through resistor R19. When the current exceeds the set current value, the transistor Q8 will conduct, and the PWM will send a signal to turn off the switching transistor Q3. When Q3 is on and D10 is off, part of the electrical energy is output to the load, and part is stored in the energy storage inductor. When Q3 is off and D10 is on, the energy in the energy storage inductor is released. At this time, part of the voltage on the output bus will charge the bus capacitor C12 through D6, and part will supply power to the load. Output filter capacitors C11 and C9 serve to smooth the output voltage and reduce output ripple.

[0067] In one example, diodes D6 and D10 are ESIJ type, with parameters of 1A forward current and 600V reverse withstand voltage; Q2 is MMBT5551 and Q5 is MMBT5401; resistor R19 is 2Ω / 0.25W / %1; and switching transistor Q3 is 2SK3562-VB. The inventor has experimentally verified that the DC-DC conversion circuit obtained with the above combination of components achieves reliable performance.

[0068] The system architecture diagram of this circuit is as follows: Figure 7 As shown, the measured waveform is as follows: Figure 8As shown. Overall, this circuit is ingeniously conceived, simple and reliable in structure, and easy to use. Through the floating circuit design, the bus capacitor is charged at the output terminal when the inductor is freewheeling, and the power supply for the front-end circuit is provided by the bus capacitor, greatly reducing power consumption and improving output efficiency. In terms of control, this invention employs a dual closed-loop control concept of voltage and current. Voltage control involves sampling the output voltage to obtain a feedback signal, forming a closed loop with the given voltage. Current feedback is obtained by sampling the inductor current, forming an inner current loop control with the given current. This improves upon the shortcomings of voltage control by enabling direct current control, improving the response speed of the inner loop and enhancing anti-interference capabilities. Within the same wide input voltage range, this invention can adjust the output voltage for different load scenarios, and the stable amplitude of the output voltage is adjustable. It also features overcurrent protection, greatly improving power supply safety.

[0069] According to another aspect of this application, an electronic device is also provided, which includes the DC-DC conversion circuit described above according to the embodiments of this application.

[0070] Based on the above description, the DC-DC conversion circuit and electronic device according to the embodiments of this application can solve the problems of high cost and high standby power consumption of existing DC-DC circuits using integrated chip solutions. They have the advantages of simple circuit, high reliability, low cost, wide input voltage range, strong load capacity, low cost and high efficiency without the need for additional heat dissipation design.

[0071] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0072] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0073] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0074] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0075] Similarly, it should be understood that, for the purpose of simplification and aiding understanding of one or more aspects of this application, various features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, the approach of this application should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with fewer features than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0076] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or elements of any method or apparatus so disclosed may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0077] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0078] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules in the article analysis device according to embodiments of this application. This application can also be implemented as a DC-DC conversion circuit program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such an implementation of this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0079] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several DC-DC conversion circuits, several of these DC-DC conversion circuits may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0080] The above are merely specific embodiments or descriptions of specific embodiments of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A direct-current-direct-current conversion circuit, characterized by comprising: The direct-current-direct-current conversion circuit comprises: a switch control circuit for outputting a control signal for controlling the switch circuit; the switch circuit, connected with the direct-current input end and the switch control circuit, for being turned on or turned off based on the control signal; a step-down circuit, connected with the switch circuit, for converting an input voltage of the direct-current input end into an output voltage based on the turn-on and turn-off of the switch circuit; a charging circuit, connected with the step-down circuit, for charging a bus capacitor in the charging circuit based on energy of an inductive freewheeling phase of the step-down circuit, the bus capacitor being capable of being used for powering the switch control circuit and / or a feedback circuit; the feedback circuit, connected with the step-down circuit, for sampling an output signal of the step-down circuit and feeding back a sampling signal to the switch control circuit.

2. The DC-DC conversion circuit according to claim 1, characterized by The charging circuit is a bootstrap capacitor charging circuit.

3. The DC-DC conversion circuit according to claim 2, characterized in that, The bootstrap capacitor charging circuit comprises: a first capacitor, the first capacitor being the bus capacitor, a first end of the first capacitor being connected with the step-down circuit and the switch control circuit, and a second end of the first capacitor being grounded; a second capacitor, a first end of the second capacitor being connected with the first end of the first capacitor, and a second end of the second capacitor being grounded; a first diode, a cathode of the first diode being connected with the first end of the first capacitor, and an anode of the first diode being connected with the step-down circuit; a first voltage stabilizing tube, a cathode of the first voltage stabilizing tube being connected with the first end of the second capacitor, and an anode of the first voltage stabilizing tube being grounded.

4. The DC-DC conversion circuit according to any one of claims 1-3, characterized by The feedback circuit comprises a voltage feedback circuit, the voltage feedback circuit being used for sampling a voltage value of the output signal of the step-down circuit and feeding back a voltage sampling result to the switch control circuit, so that the switch control circuit outputs a control signal for controlling the switch circuit based on the voltage sampling result.

5. The DC-DC conversion circuit according to claim 4, characterized in that, The voltage feedback circuit comprises: a second voltage stabilizing tube, a cathode of the second voltage stabilizing tube being connected with the switch control circuit, and an anode of the second voltage stabilizing tube being connected with a first end of a second resistor; the second resistor, a second end of the second resistor being connected with a first end of a third capacitor and a base of a first triode; the third capacitor, a second end of the third capacitor being grounded; the first triode, a collector of the first triode being connected with the switch control circuit, and an emitter of the first triode being grounded.

6. The DC-DC conversion circuit according to claim 4, characterized by The feedback circuit further comprises a current feedback circuit, the current feedback circuit being used for sampling a current value of the output signal and feeding back a current sampling result to the switch control circuit, so that the switch control circuit outputs a control signal for controlling the switch circuit based on the voltage sampling result and the current sampling result.

7. The DC-DC conversion circuit according to claim 6, characterized in that The current feedback circuit is connected with the switch control circuit, and the current feedback circuit is further used for overcurrent protection, and the bus capacitor is capable of being used for powering the current feedback circuit.

8. The DC-DC conversion circuit according to claim 6 or 7, characterized in that, The current feedback circuit comprises: a first resistor, a first end of the first resistor being connected with the step-down circuit, and a second end of the first resistor being connected with a first end of a third resistor; The third resistor, the second end of the third resistor is connected with the first end of the fourth capacitor and the base of the second triode; The fourth capacitor, the second end of the fourth capacitor is grounded; The second triode, the emitter of the second triode is grounded, and the collector of the second triode is connected with the switch control circuit.

9. The DC-DC conversion circuit according to any one of claims 1-3, characterized by The direct current-direct current conversion circuit further comprises: A soft start circuit, which is connected with the switch control circuit and the feedback circuit, and is used for inhibiting the impact current and voltage overshoot in the direct current-direct current conversion circuit.

10. The DC-DC conversion circuit according to claim 9, characterized by The soft start circuit comprises: A third triode, the base of the third triode is connected with the feedback circuit, and the collector of the third triode is grounded; A fifth capacitor, the first end of the fifth capacitor is connected with the second end of the fourth resistor and the positive input end of the comparator, and the second end of the fifth capacitor is grounded; The fourth resistor, the first end of the fourth resistor is connected with the first end of the fifth resistor; The fifth resistor, the second end of the fifth resistor is connected with the output end of the comparator; The comparator, the negative input end of the comparator is connected with a reference signal.

11. The dc-dc conversion circuit according to any one of claims 1-3, characterized by The switch control circuit is a totem pole topology switch control circuit.

12. The DC-DC conversion circuit according to claim 11, characterized by The totem pole topology switch control circuit comprises: A fourth triode, the base of the fourth triode is connected with the feedback circuit, the collector of the fourth triode is connected with the first end of the sixth resistor, and the emitter of the fourth triode is connected with the collector of the fifth triode; The fifth triode, the base of the fifth triode is connected with the base of the fourth triode, and the emitter of the fifth triode is grounded; The sixth resistor, the second end of the sixth resistor is connected with the cathode of the third zener diode; The third zener diode, the anode of the third zener diode is connected with the base of the sixth triode; The sixth triode, the collector of the sixth triode is connected with the second end of the seventh resistor and the cathode of the fourth zener diode, and the emitter of the sixth triode is grounded; The seventh resistor, the first end of the seventh resistor is connected with the base of the seventh triode; The seventh triode, the collector of the seventh triode is connected with the first end of the sixth resistor, and the emitter of the seventh triode is connected with the charging circuit; The fourth zener diode, the anode of the fourth zener diode is grounded.

13. The dc-dc conversion circuit according to any one of claims 1-3, characterized by The switch circuit is a MOS switch circuit.

14. The DC-DC conversion circuit according to claim 13, characterized by The MOS switch circuit comprises: A MOS transistor, the gate of the MOS transistor is connected with the first end of the sixth capacitor, the source of the MOS transistor is connected with the second end of the eighth resistor, and the drain of the MOS transistor is connected with the direct current input end; The sixth capacitor, the second end of the sixth capacitor is connected with the second end of the eighth resistor; The eighth resistor, the first end of the eighth resistor is connected with the first end of the ninth resistor and the first end of the sixth capacitor; The ninth resistor, the second end of the ninth resistor is connected with the switch control circuit.

15. The dc-dc conversion circuit according to any one of claims 1-3, characterized by The step-down circuit comprises: An inductor, the first end of the inductor is connected with the cathode of the second diode, and the second end of the inductor is connected with the first end of the seventh capacitor; The second diode, the anode of the second diode is grounded; The seventh capacitor, the second end of the seventh capacitor is grounded; An eighth capacitor, a first end of the eighth capacitor is connected to the first end of the seventh capacitor, and a second end of the eighth capacitor is grounded; A tenth resistor, a first end of the tenth resistor is connected to the first end of the eighth capacitor, and a second end of the tenth resistor is connected to an anode of a light emitting element; The light emitting element, a cathode of the light emitting element is grounded.

16. The dc-dc conversion circuit according to any one of claims 1-3, characterized by The direct-current-direct-current conversion circuit further comprises: A voltage dividing and current limiting circuit, the voltage dividing and current limiting circuit is connected to the switch control circuit, the charging circuit and the feedback circuit, and the direct-current input end precharges the bus capacitor via the voltage dividing and current limiting circuit.

17. The DC-DC conversion circuit according to claim 16, characterized by The voltage dividing and current limiting circuit comprises: An eleventh resistor, a first end of the eleventh resistor is connected to the direct-current input end, and a second end of the eleventh resistor is connected to a first end of a twelfth resistor; The twelfth resistor, a second end of the twelfth resistor is connected to the switch control circuit, the charging circuit and the feedback circuit.

18. An electronic device, comprising: The electronic device comprises the direct-current-direct-current conversion circuit of any one of claims 1-17.

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