Switching power supply circuit

Abstract

The embodiment of the invention provides a switching power supply circuit. The circuit comprises a critical voltage circuit, a sampling voltage circuit and a conversion output circuit, the conversion output circuit comprises an inductor; a loop is formed between the critical voltage circuit and the conversion output circuit; the critical voltage circuit is used for selecting the larger one from the current loop average current and the current critical current and converting the larger one into critical voltage to be output; the sampling voltage circuit is used for sampling the current in the inductor and converting the current into sampling voltage to be output; and the conversion output circuit is coupled to the critical voltage circuit and the sampling voltage circuit and is used for charging the inductor when the critical voltage is greater than the sampling voltage and discharging the inductor when the critical voltage is not greater than the sampling voltage so as to obtain the output voltage. The circuit is used for realizing rapid switching between a continuous conduction mode and an intermittent conduction mode.

Description

Technical Field

[0001] The present application relates to the field of electronics, and in particular to a switching power supply circuit. Background Art

[0002] In a DC-DC (Direct Current-Direct Current) power supply, there are two operating modes: CCM (Continuous Conduction Mode) and DCM (Discontinuous Conduction Mode).

[0003] In practical applications, the DC-DC power supply will automatically switch between CCM mode and DCM mode according to the load and working conditions to ensure the stability and working efficiency of the system. In order to improve the response speed and efficiency of the system, it is hoped to provide a switching power supply circuit that can achieve fast switching between CCM mode and DCM mode. Summary of the invention

[0004] An embodiment of the present application provides a switching power supply circuit for realizing rapid switching between a continuous conduction mode and a discontinuous conduction mode.

[0005] In a first aspect, an embodiment of the present application provides a switching power supply circuit, comprising: a critical voltage circuit, a sampling voltage circuit and a conversion output circuit; the conversion output circuit comprises an inductor; a loop is formed between the critical voltage circuit and the conversion output circuit; the critical voltage circuit is used to select the larger one from the current loop average current and the critical current, and convert it into a critical voltage for output; the sampling voltage circuit is used to sample the current in the inductor and convert it into a sampling voltage for output; the conversion output circuit is coupled to the critical voltage circuit and the sampling voltage circuit, and is used to charge the inductor when the critical voltage is greater than the sampling voltage, and to discharge the inductor when the critical voltage is not greater than the sampling voltage to obtain an output voltage.

[0006] In one possible embodiment, the critical voltage circuit includes a current acquisition circuit, a critical branch circuit, a selection circuit and a first current-voltage conversion circuit; the current acquisition circuit is used to obtain a loop average current based on a target voltage and an output voltage of a conversion output circuit; the critical branch circuit receives an input voltage and an output voltage of the conversion output circuit, and is used to obtain a critical current based on the input voltage and the output voltage of the conversion output circuit; the selection circuit is coupled to the current acquisition circuit and the critical branch circuit, and is used to output a loop average current when the loop average current output by the current acquisition circuit is greater than the critical current output by the critical branch circuit; and, when the loop average current output by the current acquisition circuit is not greater than the critical current output by the critical branch circuit, output a critical current; the input end of the first current-voltage conversion circuit is connected to the output end of the selection circuit and the conversion output circuit, and is used to obtain a critical voltage based on a current signal output by the selection circuit.

[0007] In one possible implementation, a current acquisition circuit includes a first sampling circuit, an error amplification circuit, and a voltage-current conversion circuit; the first sampling circuit is connected to a conversion output circuit and an error amplification circuit, and is used to obtain a feedback voltage based on an output voltage sampling of the conversion output circuit; the error amplification circuit is used to obtain a current error voltage based on a target voltage and a feedback voltage; an input end of the voltage-current conversion circuit is connected to an output end of the error amplification circuit, an output end of the voltage-current conversion circuit is connected to a selection circuit, and the voltage-current conversion circuit is used to obtain a loop average current based on the current error voltage.

[0008] In one possible implementation, the error amplifier circuit includes an error amplifier, a first resistor, and a capacitor; the non-inverting input terminal of the error amplifier receives a target voltage, and the inverting input terminal of the error amplifier receives a feedback voltage; the output terminal of the error amplifier is connected to one end of the first resistor and the input terminal of the voltage-current conversion circuit; the other end of the first resistor is connected to one end of the capacitor, and the other end of the capacitor is grounded.

[0009] In one possible implementation, the first sampling circuit includes a second resistor and a third resistor; one end of the second resistor is connected to the conversion output circuit, the other end of the second resistor is connected to one end of the third resistor and the error amplifier circuit at a connection point, and the other end of the third resistor is grounded; the connection point is used to output a feedback voltage.

[0010] In a possible implementation, the first current-voltage conversion circuit includes a fourth resistor; one end of the fourth resistor is connected to the output end of the amplifier selection circuit and the conversion output circuit, and the other end of the fourth resistor is grounded.

[0011] In one possible implementation, the sampling voltage circuit includes a second sampling circuit and a second current-voltage conversion circuit; the input end of the second sampling circuit is connected to the inductor, and the second sampling circuit is used to sample the current in the inductor to obtain the sampling current; the input end of the second current-voltage conversion circuit is connected to the output end of the second sampling circuit and the conversion output circuit, and is used to obtain the sampling voltage according to the sampling current.

[0012] In a possible implementation, the second current-voltage conversion circuit includes a fifth resistor; one end of the fifth resistor is connected to the output end of the second sampling circuit and the conversion output circuit, and the other end of the fifth resistor is grounded.

[0013] In one possible implementation, the conversion output circuit includes a control circuit and a first output circuit, the first output circuit includes an inductor; the control circuit is coupled to the critical voltage circuit and the sampling voltage circuit, and is used to output a control signal of a first state when the critical voltage is greater than the sampling voltage; and output a control signal of a second state when the critical voltage is not greater than the sampling voltage; the first output circuit is coupled to the output end of the control circuit, and is used to charge the inductor in response to the control signal of the first state; and discharge the inductor in response to the control signal of the second state.

[0014] In one possible implementation, the control circuit includes a voltage comparator and a driving module; the non-phase input terminal of the voltage comparator is connected to the output terminal of the critical voltage circuit, the inverting input terminal of the voltage comparator is connected to the output terminal of the sampling voltage circuit, the output terminal of the voltage comparator is connected to the input terminal of the driving module, the voltage comparator is used to output an indication signal of a third state when the critical voltage is greater than the sampling voltage; and output an indication signal of a fourth state when the critical voltage is not greater than the sampling voltage; the output terminal of the driving module is connected to the first output circuit, and the driving module is used to output a control signal of a first state when the indication signal is in a third state; and output a control signal of a second state when the indication signal is in a fourth state.

[0015] In the switching power supply circuit provided by the embodiment of the present application, the critical voltage circuit selects the larger one from the current loop average current and the critical current to convert into the critical voltage, the sampling voltage circuit samples the inductor current in the conversion output circuit and converts it into the sampling voltage, and the conversion output circuit charges and discharges the inductor according to the magnitude relationship between the critical voltage and the sampling voltage, thereby generating an output voltage. The scheme of the present application, by setting the critical voltage circuit, when it is necessary to switch to the DCM mode, there is no need to change the amplitude of the inductor current too much, but to achieve the output voltage in the DCM mode through the periodic interval of the inductor current, so when the DCM mode is switched back to the CCM mode, there is no need to wait for a long time for the amplitude of the inductor current to switch, thereby achieving a fast switch between the CCM mode and the DCM mode, outputting the corresponding voltage, improving the circuit response speed and work efficiency, and also reducing the ripple of the system at the switching point, improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0017] Figure 1 This is a schematic diagram of the change of inductor current when the switching power supply circuit is working;

[0018] Figure 2 A schematic diagram of the change of inductor current when the switching power supply circuit in the present application scheme is working;

[0019] Figure 3 exemplarily shows a structural schematic diagram of a switching power supply circuit provided in Embodiment 1 of the present application;

[0020] Figure 4 It is a schematic diagram of the change of output current;

[0021] Figure 5 A schematic diagram of a switching power supply circuit provided for this example;

[0022] Figure 6 A schematic diagram of a switching power supply circuit provided as an example;

[0023] Figure 7 A schematic diagram of a switching power supply circuit provided as an example;

[0024] Figure 8 A schematic diagram of a switching power supply circuit provided as an example;

[0025] Fig. 9 A schematic diagram of the structure of a switching power supply circuit provided for this example.

[0026] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0027] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application.

[0028] The terms "including" and "having" in this application are used to express an open-ended inclusion, and mean that in addition to the listed elements / components / etc., there may be additional elements / components / etc.; the terms "first" and "second" etc. are only used as marks or distinctions, and are not intended to limit the order or quantity of their objects. In addition, the different elements and areas in the drawings are only shown schematically, and are therefore not limited to the sizes or distances shown in the drawings. The technical solution is described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0029] A DC-DC power supply is a voltage converter, and its main function is to convert a DC power supply of one voltage into a DC power supply of another voltage. A DC-DC power supply can provide the operating voltage required by the load by stepping up or down. A DC-DC power supply is a type of switching power supply, which uses the energy storage characteristics of capacitors and inductors to perform high-frequency switching actions through a controllable switch, stores the input electrical energy in the inductor (or capacitor), and then releases the electrical energy to the load when the switch is disconnected to provide energy.

[0030] In practical applications, DC-DC switching power supply circuits have two different operating modes: CCM and DCM. In CCM mode, the inductor current continues to flow throughout the switching cycle, and the waveform of the inductor current is continuous in this mode; in DCM mode, the inductor current will have a zero point during the switching cycle, and the waveform of the inductor current is discontinuous in this mode.

[0031] The switch between CCM mode and DCM mode depends on the load and operating conditions. When the load is large, the circuit needs to work in CCM mode; when switching to a smaller load, the circuit needs to reduce the output voltage and switch from CCM mode to DCM mode. Figure 1This is a schematic diagram of the inductor current changes when the switching power supply circuit is working. Figure 1 As shown in the figure, when the load is large, the circuit is in CCM mode, and the inductor current remains continuously turned on throughout the switching cycle, just like the change of Peak1. When switching to a smaller load, the output voltage of the circuit decreases, and the output current gradually decreases. Corresponding to the Peak2 state, the valley current of the inductor will decrease to 0, and this state is defined as a critical state. If this state is not processed, when the output current of the circuit continues to decrease, the peak value of the inductor current will be lower, that is, Peak3<Peak2, and enter the DCM mode. If the system needs to switch from DCM mode back to CCM mode at this time, the peak value of the inductor current needs to switch from Peak3 to Peak2 and then to Peak1. In this process, it is controlled by the internal circuit, and the system response speed will be very slow, the transient response is very poor, and the ripple at the switching point is also large, affecting the stability and working efficiency of the system.

[0032] The technical content provided by this application is intended to solve the above-mentioned technical problems in related technologies. In the solution of this application, when the output current of the circuit gradually decreases, the peak value of the inductor current is controlled in a critical state, such as Figure 2 As shown, Peak4=Peak2( Figure 1 At this time, since the Peak value of the system remains unchanged, the circuit will automatically control the time between the two cycles, that is, T1-T3 gradually increases. If the circuit switches from DCM mode to CCM mode at this time, the corresponding Peak current value only needs to switch from Peak4 (i.e. Peak2) to Peak1, eliminating the process of Peak3, with a small change range, fast response speed, and small ripple at the corresponding switching point, ensuring the stability and working efficiency of the system.

[0033] In the embodiment of the present application, the critical voltage circuit selects the larger one from the current loop average current and the critical current to convert into the critical voltage, the sampling voltage circuit samples the inductor current in the conversion output circuit and converts it into the sampling voltage, and the conversion output circuit charges and discharges the inductor according to the magnitude relationship between the critical voltage and the sampling voltage, thereby generating an output voltage. The scheme of the present application, by setting the critical voltage circuit, when it is necessary to switch to the DCM mode, there is no need to change the amplitude of the inductor current too much, but to achieve the output voltage in the DCM mode through the cycle interval of the inductor current, so when the DCM mode is switched back to the CCM mode, there is no need to wait for a long time for the amplitude of the inductor current to switch, thereby achieving a fast switch between the CCM mode and the DCM mode, outputting the corresponding voltage, improving the circuit response speed and work efficiency, and also reducing the ripple of the system at the switching point, improving the stability of the system.

[0034] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0035] Embodiment 1

[0036] Figure 3 FIG. 4 is a schematic diagram showing a structure of a switching power supply circuit provided in Embodiment 1 of the present application. Figure 3 As shown, the circuit includes: a critical voltage circuit 30, a sampling voltage circuit 31 and a conversion output circuit 32; the conversion output circuit 32 includes an inductor L; a loop is formed between the critical voltage circuit 30 and the conversion output circuit 32;

[0037] A critical voltage circuit 30 is used to select the larger one from the current loop average current and the critical current, and convert it into a critical voltage for output;

[0038] The sampling voltage circuit 31 is used to sample the current in the inductor L and convert it into a sampling voltage for output;

[0039] The conversion output circuit 32 is coupled to the critical voltage circuit 30 and the sampling voltage circuit 31, and is used to charge the inductor L when the critical voltage is greater than the sampling voltage, and to discharge the inductor L when the critical voltage is not greater than the sampling voltage, so as to obtain an output voltage.

[0040] In this example, the conversion output circuit 32 is coupled to the critical voltage circuit 30 and the sampling voltage circuit 31, and the conversion output circuit 32 has an input end and an output end. The input end of the conversion output circuit 32 is used to receive the first power supply voltage, and the output end of the conversion output circuit 32 is used to output the second power supply voltage (i.e., the output voltage). Among them, the second power supply voltage (i.e., the output voltage) is obtained after the first power supply voltage is converted through the internal control of the switching power supply circuit. The first power supply voltage and the second power supply voltage (i.e., the output voltage) are different in size, which is determined by the actual working conditions of the switching power supply circuit.

[0041] Specifically, in the entire switching power supply circuit, the second power supply voltage (i.e., output voltage) outputted from the output end of the conversion output circuit 32 is fed back to the critical voltage circuit 30, thereby forming a control loop. The control loop is a part used to adjust the output voltage of the power supply, reflecting the current waveform of the power supply under a stable working state. A target voltage is also set in the switching power supply circuit, and the difference between the second power supply voltage (i.e., output voltage) outputted from the output end of the conversion output circuit 32 and the target voltage is fed back in real time. The loop average current refers to the average current flowing in the control loop of the switching power supply circuit. In a DC-DC power supply, based on volt-second balance and basic loop control, the current loop average current can be calculated by the second power supply voltage (i.e., output voltage) currently outputted by the conversion output circuit 32 and the target voltage in the switching power supply circuit.

[0042] Accordingly, during the operation of the switching power supply circuit, when switching to a smaller load, the output current of the conversion output circuit 32 decreases. During this process, the valley current of the inductor in the conversion output circuit 32 will decrease to 0, and the current in the loop at this time is defined as the critical current, which can be calculated by the first power supply voltage input at the input end of the conversion output circuit 32 and the current second power supply voltage (i.e., the output voltage).

[0043] In this example, after calculating the current loop average current and critical current, the critical voltage circuit 30 selects the larger one from the current loop average current and critical current, and converts it into a critical voltage for output. When the load in the switching power supply circuit is large, the switching power supply circuit is in CCM mode. At this time, the current loop average current is greater than the critical current, so the current loop average current is selected and the current loop average current is converted into a critical voltage for output; as the circuit is working, when switching to a smaller load, the loop average current gradually decreases, and the current loop average current is less than the critical current. The switching power supply circuit enters DCM mode, then the critical current is selected and the critical current is converted into a critical voltage for output. Figure 4 This is a schematic diagram of the output current change. Figure 4 As shown, “-” indicates the average current of the loop; “---” indicates the critical current; Indicates the selected output current. Figure 4It can be seen that when the switching power supply circuit starts to work, the load is large and the average loop current is greater than the critical current. At this time, the average loop current output is selected; when it is switched to a smaller load, the average loop current continues to decrease. When it drops to the critical current, the critical current output is selected and remains unchanged. There are many ways to convert current into voltage, which are not limited here. For example, a resistor is set, and a voltage output proportional to the current can be generated by passing current through a fixed resistor. According to Ohm's law, voltage is equal to current multiplied by resistance value. For another example, a current-voltage converter can be set up, and a specially designed circuit, such as a converter or amplifier, can be used to convert the current signal into a corresponding voltage output.

[0044] Specifically, the conversion output circuit 32 includes an inductor L, and the sampling voltage circuit 31 samples the current in the inductor L in the conversion output circuit 32, and converts it into a sampling voltage for output. A switch for controlling the conduction and disconnection of the circuit where the inductor L is located is set in the conversion output circuit 32. The conversion output circuit 32 receives the critical voltage and the sampling voltage. When the critical voltage is greater than the sampling voltage, the control signal for controlling the switch to be turned on is output to charge the inductor L. After the inductor L is charged, when the critical voltage is not greater than the sampling voltage, the control signal for controlling the switch to be turned off is output to discharge the inductor L and transmit it to the load to obtain the output voltage.

[0045] In the above example, by setting the critical voltage circuit 30, when the average loop current is less than the critical current, the critical current output is selected, so that it can respond faster when the DCM mode is switched back to the CCM mode, realize fast switching between the CCM mode and the DCM mode, and output the corresponding voltage, thereby accelerating the response speed and improving the work efficiency. At the same time, the ripple of the system at the switching point is reduced, and the stability of the system is improved.

[0046] Specifically, the critical voltage circuit 30 is used to select the larger current between the current loop average current and the critical current and convert it into a critical voltage output. The specific implementation structure of the critical voltage circuit 30 is not limited. In one example, Figure 5 A schematic diagram of a switching power supply circuit provided for this example is shown in FIG. Figure 5 As shown, the critical voltage circuit 30 includes a current acquisition circuit 301, a critical branch circuit 302, a large selection circuit 303 and a first current-voltage conversion circuit 304;

[0047] The current acquisition circuit 301 is used to obtain the loop average current according to the target voltage and the output voltage of the conversion output circuit 32;

[0048] The critical branch circuit 302 receives the input voltage and the output voltage of the conversion output circuit 32, and is used to obtain the critical current according to the input voltage and the output voltage of the conversion output circuit 32;

[0049] The large selection circuit 303 is coupled to the current acquisition circuit 301 and the critical branch circuit 302, and is used to output the loop average current when the loop average current output by the current acquisition circuit 301 is greater than the critical current output by the critical branch circuit 302; and output the critical current when the loop average current output by the current acquisition circuit 301 is not greater than the critical current output by the critical branch circuit 302;

[0050] The input end of the first current-voltage conversion circuit 304 is connected to the output end of the amplifier circuit 303 and the conversion output circuit 32 , and is used to obtain a critical voltage according to the current signal output by the amplifier circuit 303 .

[0051] Among them, the output voltage of the conversion output circuit 32 is controlled by the loop and fed back to the current acquisition circuit 301. The target voltage is set according to the actual working condition of the switching power supply circuit. The current acquisition circuit 301 receives the target voltage and the output voltage of the conversion output circuit 32, calculates the difference voltage between the output voltage of the current conversion output circuit 32 and the target voltage, and converts the difference voltage to obtain the loop average current. Among them, there are many ways to convert voltage into current, which are not limited here. For example, by connecting a resistor in series, according to Ohm's law, the relationship between voltage and resistance value can be converted into current output. For example, a current amplifier is set. By using the current amplifier, the input voltage signal can be amplified into a corresponding current output.

[0052] Specifically, the critical branch circuit 302 receives the input voltage and output voltage of the conversion output circuit 32. In combination with the above example, the input voltage of the conversion output circuit 32 is the first power supply voltage input at the input end, and the output voltage is the second power supply voltage (i.e., output voltage) output at the output end. The critical current can be calculated by the first power supply voltage input at the input end of the conversion output circuit 32 and the current second power supply voltage (i.e., output voltage). The calculation formula is as follows:

[0053]

[0054] Among them, I criticalRepresents the critical current; m1 represents a constant; v2 represents the second power supply voltage (i.e., the output voltage); v1 represents the first power supply voltage. After the loop average current and the critical current are calculated, the large selection circuit 303 receives the current loop average current and the critical current. At this time, the large selection circuit 303 outputs the larger of the loop average current and the critical current through internal control selection. When the loop average current output by the current acquisition circuit 301 is greater than the critical current output by the critical branch circuit 302, the larger loop average current is selected to be output; when the loop average current output by the current acquisition circuit 301 is not greater than the critical current output by the critical branch circuit 302, the larger critical current is selected to be output.

[0055] More specifically, after the selection circuit 303 outputs the larger current signal between the loop average current and the critical current, it is input into the first current-voltage conversion circuit 304 and converted into a critical voltage. There is no limit to the way to convert the larger current signal into the critical voltage, for example, a resistor can be set in the first current-voltage conversion circuit 304. In one example, the first current-voltage conversion circuit 304 includes a fourth resistor R4; one end of the fourth resistor R4 is connected to the output end of the selection circuit 303 and the conversion output circuit 32, and the other end of the fourth resistor R4 is grounded.

[0056] In the above example, the current acquisition circuit 301 obtains the loop average current, the critical branch circuit 302 obtains the critical current, and the large selection circuit 303 selects the larger current signal between the loop average current and the critical current to output to the first current-voltage conversion circuit 304 for conversion into a critical voltage. By setting the large selection circuit 303, when the loop average current is less than the critical current, the critical current output is selected, so that the switching power supply circuit has a faster response when switching from the DCM mode back to the CCM mode, thereby improving the working efficiency.

[0057] Figure 6 The schematic diagram of the structure of a switching power supply circuit provided as an example. Figure 6 As shown, the current acquisition circuit 301 includes a first sampling circuit 3011, an error amplifier circuit 3012 and a voltage-current conversion circuit 3013;

[0058] The first sampling circuit 3011 is connected to the conversion output circuit 32 and the error amplifier circuit 3012, and is used to obtain a feedback voltage based on the output voltage sampling of the conversion output circuit 32;

[0059] The error amplifier circuit 3012 is used to obtain the current error voltage according to the target voltage and the feedback voltage;

[0060] The input end of the voltage-to-current conversion circuit 3013 is connected to the output end of the error amplifier circuit 3012, and the output end of the voltage-to-current conversion circuit 3013 is connected to the amplification circuit 303. The voltage-to-current conversion circuit 3013 is used to obtain the loop average current according to the current error voltage.

[0061] In this example, the first sampling circuit 3011 samples the second power supply voltage (i.e., output voltage) output by the conversion output circuit 32 to obtain a feedback voltage which is input into the error amplifier circuit 3012. In one example, the feedback voltage can be obtained by resistor voltage division. Figure 6 As shown, the first sampling circuit 3011 includes a second resistor R2 and a third resistor R3; one end of the second resistor R2 is connected to the conversion output circuit 32, and the other end of the second resistor R2 is connected to one end of the third resistor R3 and the error amplifier circuit 3012 at a connection point, and the other end of the third resistor R3 is grounded; the connection point is used to output the feedback voltage. Sampling is performed at the connection point to obtain the feedback voltage and input it into the error amplifier circuit 3012. The calculation formula is as follows:

[0062]

[0063] Among them, V FB represents the feedback voltage; V2 represents the second power supply voltage (ie, the output voltage); R2 represents the second resistor; and R3 represents the third resistor.

[0064] Specifically, the error amplifier circuit 3012 receives the preset target voltage and the sampled feedback voltage, and obtains the current error voltage by calculation. The calculation formula is as follows:

[0065] ΔV=m2·(V FB -V REF )

[0066] Where ΔV represents the error voltage; m2 represents a constant; V FB Represents the feedback voltage; V REF The specific implementation structure of the error amplifier circuit 3012 is not limited. In one example, Figure 6As shown, the error amplifier circuit 3012 includes an error amplifier EA, a first resistor R1 and a capacitor C1; the non-inverting input terminal of the error amplifier EA receives the target voltage, and the inverting input terminal of the error amplifier EA receives the feedback voltage; the output terminal of the error amplifier EA is connected to one end of the first resistor R1 and the input terminal of the voltage-current conversion circuit 3013; the other end of the first resistor R1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is grounded. The error amplifier EA has a non-inverting input terminal and a reverse input terminal. Based on the principle of the feedback network, the input signal of the reverse input terminal and the signal input of the non-inverting input terminal are subtracted, and then the difference signal is fed back to the output terminal of the error amplifier EA, thereby reducing the error between the target voltage and the feedback voltage. In combination with the above example, the non-inverting input terminal of the error amplifier EA receives the target voltage, and the inverting input terminal of the error amplifier EA receives the feedback voltage sampled by the first sampling circuit 3011, and the operation is performed inside the error amplifier EA to output the current error voltage to the voltage-current conversion circuit 3013. The voltage-to-current conversion circuit 3013 includes a resistor. After receiving the error voltage, the voltage-to-current conversion circuit 3013 divides the current error voltage by the resistance value to calculate and obtain the loop average current.

[0067] Through the scheme of this example, the error amplifier circuit 3012 receives the target voltage and the feedback voltage sampled by the first sampling circuit 3011, outputs the error voltage, and converts it into the loop average current through the voltage-to-current conversion circuit 3013, so as to realize the loop control of the circuit and improve the stability of the system.

[0068] Figure 7 The schematic diagram of the structure of a switching power supply circuit provided as an example. The sampling voltage circuit 31 includes a second sampling circuit 311 and a second current-voltage conversion circuit 312;

[0069] The input end of the second sampling circuit 311 is connected to the inductor L. The second sampling circuit 311 is used to sample the current in the inductor L to obtain the sampled current;

[0070] The input end of the second current-voltage conversion circuit 312 is connected to the output end of the second sampling circuit 311 and the conversion output circuit 32, and is used to obtain a sampling voltage according to the sampling current.

[0071] In this example, the input end of the second sampling circuit 311 is connected to the inductor L in the conversion output circuit 32, and during the operation of the switching power supply circuit, the current in the inductor L is sampled. When the switch that controls the conduction of the circuit where the inductor L is located is turned on, the inductor L is charged at this time, and the current in the inductor L will continue to rise. When the inductor L is fully charged, the switch that controls the conduction of the circuit where the inductor L is located is turned off, and the inductor L is discharged at this time, and the current in the inductor L continues to decrease. During this whole process, the current in the inductor L is sampled.

[0072] Specifically, the second sampling circuit 311 samples the current in the inductor L and transmits it to the second current-voltage conversion circuit 312, and converts the sampled current into a sampled voltage. There is no limit to the way of converting the sampled current into the sampled voltage, for example, a resistor can be set in the second current-voltage conversion circuit 312. In one example, the second current-voltage conversion circuit 312 includes a fifth resistor R5; one end of the fifth resistor R5 is connected to the output end of the second sampling circuit 311 and the conversion output circuit 32, and the other end of the fifth resistor R5 is grounded.

[0073] In the above example, the second sampling circuit 311 samples the current in the inductor L, and converts it into a sampling voltage through the second current-to-voltage conversion circuit 312 and transmits it to the conversion output circuit 32, which can realize the loop control of the circuit and improve the stability of the system.

[0074] Specifically, the way of controlling the circuit where the inductor L in the conversion output circuit 32 is turned on and off is not limited. In one example, Figure 8 The schematic diagram of the structure of a switching power supply circuit provided as an example. Figure 8 As shown, the conversion output circuit 32 includes a control circuit 321 and a first output circuit 322, and the first output circuit 322 includes an inductor L;

[0075] The control circuit 321 is coupled to the critical voltage circuit 30 and the sampling voltage circuit 31, and is used to output a control signal of a first state when the critical voltage is greater than the sampling voltage; and output a control signal of a second state when the critical voltage is not greater than the sampling voltage;

[0076] The first output circuit 322 is coupled to the output terminal of the control circuit 321 , and is used for charging the inductor L in response to a control signal of a first state, and discharging the inductor L in response to a control signal of a second state.

[0077] In this example, the first output circuit 322 includes an inductor L, a first switch K1 for controlling the charging and discharging of the inductor L, a second switch K2, and a load capacitor C2. Figure 8 As shown, one end of the first switch K1 is connected to one end of the inductor L and one end of the second switch K2, the other end of the first switch K1 is grounded, and the control end of the first switch K1 is connected to the control circuit 321; the other end of the inductor L is connected to the input end of the conversion output circuit 32; the other end of the second switch K2 is connected to one end of the load capacitor C2, and the control end of the second switch K2 is connected to the control circuit 321; the other end of the load capacitor C2 is grounded. The first switch K1 and the second switch K2 can be MOS tubes or other components, which are not limited here.

[0078] In one example, the first switch K1 is an NMOS tube, and the second switch K2 is a PMOS tube. The control circuit 321 receives the critical voltage output by the critical voltage circuit 30 and the sampling voltage output by the sampling voltage circuit 31. When the critical voltage is greater than the sampling voltage, the control circuit 321 outputs a control signal of the first state, that is, the first state is a high level. At this time, the first output circuit 322 responds to the high-level control signal, controls the first switch K1 to turn on, the second switch K2 to turn off, and charges the inductor L; when the critical voltage is not greater than the sampling voltage, the control circuit 321 outputs a control signal of the second state, that is, the second state is a low level. At this time, the first output circuit 322 responds to the low-level control signal, controls the first switch K1 to turn off, the second switch K2 to turn on, and discharges the inductor L, thereby transmitting electrical energy to the load capacitor C2.

[0079] In another example, the first switch K1 is a PMOS tube, and the second switch K2 is an NMOS tube. The control circuit 321 receives the critical voltage output by the critical voltage circuit 30 and the sampling voltage output by the sampling voltage circuit 31. When the critical voltage is greater than the sampling voltage, the control circuit 321 outputs a control signal of the first state, that is, the first state is a low level. At this time, the first output circuit 322 responds to the low-level control signal, controls the first switch K1 to turn on, the second switch K2 to turn off, and charges the inductor L; when the critical voltage is not greater than the sampling voltage, the control circuit 321 outputs a control signal of the second state, that is, the second state is a high level. At this time, the first output circuit 322 responds to the high-level control signal, controls the first switch K1 to turn off, the second switch K2 to turn on, and discharges the inductor L, thereby transmitting electrical energy to the load capacitor C2.

[0080] In the above example, by setting the first switch K1 and the second switch K2 in the circuit where the inductor L is located, and responding to the control signals of the control circuit 321 in different states to charge and discharge the inductor L, the circuit can be independently controlled to ensure the stability of the system operation.

[0081] Specifically, the control circuit 321 is used to output control signals of different states. The specific implementation structure of the control circuit 321 is not limited. Figure 8 As shown, the control circuit 321 includes a voltage comparator LM and a driving module 3211;

[0082] The positive input terminal of the voltage comparator LM is connected to the output terminal of the critical voltage circuit 30, the negative input terminal of the voltage comparator LM is connected to the output terminal of the sampling voltage circuit 31, and the output terminal of the voltage comparator LM is connected to the input terminal of the driving module 3211. The voltage comparator LM is used to output an indication signal of a third state when the critical voltage is greater than the sampling voltage; and output an indication signal of a fourth state when the critical voltage is not greater than the sampling voltage.

[0083] The output end of the driving module 3211 is connected to the first output circuit 322. The driving module 3211 is used to output a control signal of the first state when the indication signal is in the third state; and output a control signal of the second state when the indication signal is in the fourth state.

[0084] In this example, the voltage comparator LM is used to compare the magnitudes of the two voltages inputted at the input terminals, and outputs a high-level or low-level indication signal according to the comparison of the voltages inputted at the input terminals of different phases. When the voltage at the positive-phase input terminal of the voltage comparator LM is greater than the voltage at the negative-phase input terminal, the voltage comparator LM outputs a high-level indication signal; when the voltage at the positive-phase input terminal of the voltage comparator LM is not greater than the voltage at the negative-phase input terminal, the voltage comparator LM outputs a low-level indication signal.

[0085] Correspondingly, the positive input terminal of the voltage comparator LM receives the critical voltage output by the critical voltage circuit 30, and the negative input terminal of the voltage comparator LM receives the sampled voltage output by the sampling voltage circuit 31. When the critical voltage is greater than the sampled voltage, that is, the voltage at the positive input terminal of the voltage comparator LM is greater than the voltage at the negative input terminal, the indication signal of the third state is output, and at this time, the third state is a high-level indication signal; when the critical voltage is not greater than the sampled voltage, that is, the voltage at the positive input terminal of the voltage comparator LM is not greater than the voltage at the negative input terminal, the indication signal of the fourth state is output, and at this time, the fourth state is a low-level indication signal. The output terminal of the voltage comparator LM is connected to the driving module 3211. When the indication signal output by the voltage comparator LM is in the third state, that is, the indication signal of the high level, the driving module 3211 outputs the control signal of the first state, and the first state can be either high or low; when the indication signal output by the voltage comparator LM is in the fourth state, that is, the indication signal of the low level, the driving module 3211 outputs the control signal of the second state, and the second state can be either high or low.

[0086] In the above example, the voltage comparator LM outputs an indication signal to control the driving module 3211 to output a corresponding control signal, thereby controlling the charging and discharging of the inductor L, realizing independent control of the circuit, and ensuring the stability of the system operation.

[0087] In the switching power supply circuit provided in this embodiment, the critical voltage circuit 30 selects the larger one from the current loop average current and the critical current to convert into the critical voltage, the sampling voltage circuit 31 samples the inductor current in the conversion output circuit 32 and converts it into the sampling voltage, and the conversion output circuit 32 charges and discharges the inductor L according to the magnitude relationship between the critical voltage and the sampling voltage, thereby generating an output voltage. The scheme of the present application, by setting the critical voltage circuit 30, when it is necessary to switch to the DCM mode, there is no need to change the amplitude of the inductor current too much, but to achieve the output voltage in the DCM mode through the cycle interval of the inductor current, so when the DCM mode is switched back to the CCM mode, there is no need to wait for a long time for the amplitude of the inductor current to switch, thereby achieving a fast switch between the CCM mode and the DCM mode, outputting the corresponding voltage, improving the circuit response speed and work efficiency, and also reducing the ripple of the system at the switching point, improving the stability of the system.

[0088] Embodiment 2

[0089] The switching power supply circuit of the above example is described below by taking a specific example.

[0090] Fig. 9 This is a schematic diagram of a switching power supply circuit provided in this example. Fig. 9 As shown, the description is as follows: Fig. 9 The error amplifier circuit 3012 includes an error amplifier EA, a first resistor R1 and a capacitor C1; the first current-voltage conversion circuit 304 includes a fourth resistor R4; the second current-voltage conversion circuit 312 includes a fifth resistor R5; the control circuit 321 includes a voltage comparator LM and a driving module 3211; the first output circuit 322 includes an inductor L, a first switch K1, a second switch K2 and a load capacitor C2; the first sampling circuit 3011 includes a second resistor R2 and a third resistor R3.

[0091] When the system is working, a feedback voltage is output at the connection point of the second resistor R2 and the third resistor R3, and is fed back to the inverting input terminal of the error amplifier EA. The positive input terminal of the error amplifier EA receives the target voltage. After being controlled internally by the error amplifier EA, the error voltage is output to the voltage-current conversion circuit 3013 and converted into a loop average current. The critical branch circuit 302 calculates the critical current according to the input voltage and the output voltage. The loop average current and the critical current are input into the selection circuit 303. When the loop average current is greater than the critical current, the loop average current is output and passes through the first current-voltage conversion circuit 304. The critical voltage is converted into a critical voltage. When the average current of the loop is not greater than the critical current, the critical current is output and converted into the critical voltage through the first current-voltage conversion circuit 304. The second sampling circuit 311 samples the current in the inductor L and converts it into a sampling voltage through the second current-voltage conversion circuit 312. The voltage comparator LM receives the critical voltage and the sampling voltage for comparison, and outputs a corresponding indication signal to the driving module 3211. The driving module 3211 outputs a control signal of a corresponding state in response to the indication signal of different states, and controls the first switch K1 and the second switch K2 to be turned on or off, thereby charging or discharging the inductor L.

[0092] Among them, the specific switching power supply circuit can refer to the content of the above embodiment. In summary, the switching power supply circuit provided in this example, by setting the critical voltage circuit 30, when it is necessary to switch to the DCM mode, there is no need to change the amplitude of the inductor current too much, but to achieve the output voltage in the DCM mode through the cycle interval of the inductor current, so when the DCM mode is switched back to the CCM mode, there is no need to wait for a long time for the amplitude of the inductor current to switch, thereby achieving fast switching between the CCM mode and the DCM mode, outputting the corresponding voltage, improving the circuit response speed and working efficiency, and can also reduce the ripple of the system at the switching point, and improve the stability of the system.

[0093] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0094] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A switching power supply circuit, characterized in that: include: A critical voltage circuit, a sampling voltage circuit and a conversion output circuit; The conversion output circuit includes an inductor; a loop is formed between the critical voltage circuit and the conversion output circuit; The critical voltage circuit is used to select the larger one from the current loop average current and the critical current, and convert it into a critical voltage for output; The sampling voltage circuit is used to sample the current in the inductor and convert it into a sampling voltage for output; The conversion output circuit is coupled to the critical voltage circuit and the sampling voltage circuit, and is used to charge the inductor when the critical voltage is greater than the sampling voltage, and to discharge the inductor when the critical voltage is not greater than the sampling voltage, so as to obtain an output voltage.

2. The switching power supply circuit according to claim 1, characterized in that: The critical voltage circuit includes a current acquisition circuit, a critical branch circuit, a large selection circuit and a first current-voltage conversion circuit; The current acquisition circuit is used to obtain the loop average current according to the target voltage and the output voltage of the conversion output circuit; The critical branch circuit receives the input voltage and the output voltage of the conversion output circuit, and is used to obtain the critical current according to the input voltage and the output voltage of the conversion output circuit; The large selection circuit is coupled to the current acquisition circuit and the critical branch circuit, and is used to output the loop average current when the loop average current output by the current acquisition circuit is greater than the critical current output by the critical branch circuit; And, when the loop average current output by the current acquisition circuit is not greater than the critical current output by the critical branch circuit, outputting the critical current; The input end of the first current-voltage conversion circuit is connected to the output end of the amplifier selection circuit and the conversion output circuit, and is used to obtain the critical voltage according to the current signal output by the amplifier selection circuit.

3. The switching power supply circuit according to claim 2, characterized in that: The current acquisition circuit includes a first sampling circuit, an error amplification circuit and a voltage-current conversion circuit; The first sampling circuit is connected to the conversion output circuit and the error amplification circuit, and is used to obtain a feedback voltage based on the output voltage sampling of the conversion output circuit; The error amplification circuit is used to obtain a current error voltage according to the target voltage and the feedback voltage; The input end of the voltage-current conversion circuit is connected to the output end of the error amplifier circuit, the output end of the voltage-current conversion circuit is connected to the amplification circuit, and the voltage-current conversion circuit is used to obtain the loop average current according to the current error voltage.

4. The switching power supply circuit according to claim 3, characterized in that: The error amplification circuit comprises an error amplifier, a first resistor and a capacitor; The non-inverting input terminal of the error amplifier receives the target voltage, and the inverting input terminal of the error amplifier receives the feedback voltage; the output terminal of the error amplifier is connected to one end of the first resistor and the input terminal of the voltage-current conversion circuit; The other end of the first resistor is connected to one end of the capacitor, and the other end of the capacitor is grounded.

5. The switching power supply circuit according to claim 3, characterized in that: The first sampling circuit includes a second resistor and a third resistor; One end of the second resistor is connected to the conversion output circuit, the other end of the second resistor is connected to one end of the third resistor and the error amplifier circuit at a connection point, and the other end of the third resistor is grounded; the connection point is used to output the feedback voltage.

6. The switching power supply circuit according to claim 2, characterized in that: The first current-voltage conversion circuit includes a fourth resistor; One end of the fourth resistor is connected to the output end of the amplifier selection circuit and the conversion output circuit, and the other end of the fourth resistor is grounded.

7. The switching power supply circuit according to claim 1, characterized in that: The sampling voltage circuit includes a second sampling circuit and a second current-voltage conversion circuit; The input end of the second sampling circuit is connected to the inductor, and the second sampling circuit is used to sample the current in the inductor to obtain a sampled current; The input end of the second current-voltage conversion circuit is connected to the output end of the second sampling circuit and the conversion output circuit, and is used to obtain the sampling voltage according to the sampling current.

8. The switching power supply circuit according to claim 7, characterized in that: The second current-voltage conversion circuit includes a fifth resistor; One end of the fifth resistor is connected to the output end of the second sampling circuit and the conversion output circuit, and the other end of the fifth resistor is grounded.

9. The switching power supply circuit according to any one of claims 1 to 8, characterized in that: The conversion output circuit includes a control circuit and a first output circuit, and the first output circuit includes the inductor; The control circuit is coupled to the critical voltage circuit and the sampling voltage circuit, and is used to output a control signal of a first state when the critical voltage is greater than the sampling voltage; and output a control signal of a second state when the critical voltage is not greater than the sampling voltage; The first output circuit is coupled to the output terminal of the control circuit, and is used for charging the inductor in response to the control signal of the first state; and discharging the inductor in response to the control signal of the second state.

10. The switching power supply circuit according to claim 9, characterized in that: The control circuit includes a voltage comparator and a driving module; The positive input terminal of the voltage comparator is connected to the output terminal of the critical voltage circuit, the negative input terminal of the voltage comparator is connected to the output terminal of the sampling voltage circuit, the output terminal of the voltage comparator is connected to the input terminal of the driving module, and the voltage comparator is used to output an indication signal of a third state when the critical voltage is greater than the sampling voltage; and output an indication signal of a fourth state when the critical voltage is not greater than the sampling voltage; The output end of the driving module is connected to the first output circuit, and the driving module is used to output the control signal of the first state when the indication signal is in the third state; and output the control signal of the second state when the indication signal is in the fourth state.

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