A control circuit and control method for a switching converter circuit

Abstract

This application discloses a control circuit for a switching converter, including an adjustment circuit and a duty cycle control circuit. The adjustment circuit receives a voltage feedback signal characterizing the switching converter, a current feedback signal characterizing the output current of the switching converter, and a feedforward signal characterizing the input voltage, and outputs a voltage adjustment signal. The duty cycle control circuit receives the voltage adjustment signal and outputs a switching control signal to the switching converter. The voltage adjustment signal decreases as the input voltage of the switching converter increases, and the adjustment amount of the voltage adjustment signal corresponding to the change in the feedforward signal increases as the output current of the switching power supply decreases. This application incorporates the input voltage into the control of the voltage adjustment signal, while also taking into account the different effects of the same input voltage change on the voltage adjustment signal under different loads, enabling the switching converter to quickly adjust transient changes in the input voltage and stabilize the output voltage.

Description

Technical Field

[0001] This invention relates to electronic circuits. More specifically, this invention relates to control circuits and control methods for switching circuits. Background Technology

[0002] Switching power supplies are widely used in power management, new energy power generation, electric vehicles, and industrial control. Figure 1 This is a schematic diagram of the circuit structure of an existing switching power supply 100. The switching power supply 100 includes a switching conversion circuit 101, a feedback circuit 102, and a duty cycle control circuit 103. The switching conversion circuit 101 may include topologies such as Buck (buck-type), Boost (boost-type), and Buck-Boost (buck-boost-boost). The feedback circuit 102 detects the output voltage VOUT and amplifies the error between the output voltage VOUT or its voltage divider and a reference voltage to generate a voltage regulation signal Vc. The voltage regulation signal Vc reflects the adjustment requirement of the output voltage VOUT. The duty cycle control circuit 103 compares the voltage regulation signal Vc with a triangular wave signal and outputs a duty cycle control signal PWM, which is used to adjust the duty cycle of the switch in the switching conversion circuit 101, thereby adjusting the output voltage VOUT and the output current IOUT.

[0003] However, when the input voltage VIN undergoes a step change, the voltage regulation signal Vc changes relatively slowly because the output of the error amplifier is usually connected to a large compensation capacitor, which makes the output voltage VOUT prone to large overshoot or undershoot.

[0004] Therefore, there is an urgent need in this field for a control circuit and control method that can effectively improve the step response speed of the input voltage and suppress the overshoot of the output voltage while maintaining system stability. Summary of the Invention

[0005] This application provides a control circuit and control method for a switching converter circuit. The control circuit of the switching converter circuit incorporates the input voltage into the control of the voltage regulation signal. At the same time, it also takes into account the different effects of the same input voltage change on the voltage regulation signal under different output current conditions of the switching converter circuit, and incorporates the output current into the control of the voltage regulation signal. This enables the switching converter circuit to quickly regulate transient changes in the input voltage and stabilize the output voltage.

[0006] According to an embodiment of the present invention, a control circuit for a switching circuit is provided, comprising: an adjustment circuit that receives a voltage feedback signal characterizing the switching circuit, a current feedback signal characterizing the output current of the switching circuit, and a feedforward signal characterizing the input voltage, and outputs a voltage adjustment signal based on the voltage feedback signal, the current feedback signal, and the feedforward signal; and a duty cycle control circuit that receives the voltage adjustment signal and outputs a switching control signal to the switching circuit based on the voltage adjustment signal to control the output voltage or output current of the switching circuit; wherein the voltage adjustment signal decreases as the feedforward signal increases and increases as the feedforward signal decreases, and when the output current of the switching power supply has a first value, the adjustment amount of the voltage adjustment signal corresponding to the change in the feedforward signal is a first adjustment amount, and when the output current of the switching power supply has a second value, the adjustment amount of the voltage adjustment signal corresponding to the change in the feedforward signal is a second adjustment amount, wherein the first value is less than the second value, and the first adjustment amount is greater than the second adjustment amount.

[0007] According to one embodiment of the present invention, a switching power supply is provided, including the aforementioned control circuit, and further including a switching conversion circuit, wherein the switching conversion circuit includes at least one switch, and the on / off state of the switch is controlled by the switch control signal.

[0008] According to an embodiment of the present invention, a control method for a switching power supply is provided, comprising: providing a feedforward signal based on the input voltage of the switching power supply; providing a current feedback signal based on the output current of the switching power supply; providing a voltage feedback signal based on the output voltage of the switching power supply; providing a voltage regulation signal based on the feedforward signal, the current feedback signal, and the voltage feedback signal; and providing a switch control signal based on the voltage regulation signal to control the on / off state of a switch in a switching conversion circuit of the switching power supply; wherein the voltage regulation signal decreases as the feedforward signal increases, and increases as the feedforward signal decreases, and when the output current of the switching power supply has a first value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is a first regulation amount, and when the output current of the switching power supply has a second value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is a second regulation amount, wherein the first value is less than the second value, and the first regulation amount is greater than the second regulation amount. Attached Figure Description

[0009] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings:

[0010] Figure 1 This is a schematic diagram of the existing switching power supply 100.

[0011] Figure 2 This is a schematic diagram of the circuit structure of a switching power supply 200 according to an embodiment of this application;

[0012] Figure 3 This is a schematic diagram of the circuit structure of a switching power supply 300 according to an embodiment of this application;

[0013] Figure 4 This is a schematic diagram of the circuit structure of a controlled current source 400 according to an embodiment of this application;

[0014] Figure 5 This is a schematic diagram of the circuit structure of a controlled current source 500 according to an embodiment of this application;

[0015] Figure 6 This is a schematic diagram of the circuit structure of a controlled current source 600 according to an embodiment of this application;

[0016] Figure 7 This is a schematic flowchart of a switching power supply control method 700 according to an embodiment of this application. Detailed Implementation

[0017] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the invention.

[0018] The terms "first," "second," etc., used in the following description are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature specified with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0019] In this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the term "coupled" can refer to a method of electrical connection for signal transmission. "Coupled" can be a direct electrical connection or an indirect electrical connection through an intermediate medium.

[0020] Figure 2 This is a schematic diagram of the circuit structure of a switching power supply 200 according to an embodiment of this application. Figure 2As shown, the switching power supply 200 includes a switching conversion circuit 21 and a control circuit 22. The switching conversion circuit 21 includes at least one switch and includes any topology that can convert the input voltage VIN into the output voltage VOUT, such as BUCK, BOOST, BUCK-BOOST, etc. The control circuit 22 includes a feedback circuit 202, an adjustment circuit 204, and a duty cycle control circuit 203.

[0021] Feedback circuit 202 receives the output voltage VOUT and provides a voltage feedback signal Vof based on the output voltage VOUT. In one embodiment, the voltage feedback signal Vof decreases as the output voltage VOUT increases and increases as the output voltage VOUT decreases.

[0022] The regulation circuit 204 receives a voltage feedback signal Vof, a current feedback signal Ifb representing the output current IOUT, and a feedforward signal Vif representing the output voltage VIN. Based on these signals, it outputs a voltage regulation signal Vc. The relationship between the voltage regulation signal Vc and the voltage feedback signals Vof, Vif, and Ifb is as follows: Vc increases as Vof increases and decreases as Vof decreases; Vc decreases as Vf increases and increases as Vf decreases; Vc decreases as Ifb increases and increases as Ifb increases. Figure 2 In this embodiment, the adjustment circuit 204 includes a first adjustment circuit 2041 and a second adjustment circuit 2042. Based on the feedforward signal Vif and the current feedback signal Ifb, the first adjustment circuit 2041 provides a feedforward adjustment signal Vir. The feedforward adjustment signal Vir increases as the feedforward signal Vif increases and decreases as it decreases. It decreases as the current feedback signal Ifb increases and decreases as it increases. Based on the feedforward adjustment signal Vir and the voltage feedback signal Vof, the first adjustment circuit 2041 provides a voltage adjustment signal Vc. The voltage adjustment signal Vc decreases as the feedforward adjustment signal Vir increases and increases as it decreases, and it increases as the voltage feedback signal Vof increases and decreases as it decreases. Figure 2 In this embodiment, the first adjustment circuit 2041 and the second adjustment circuit 2042 only represent the corresponding relationship between their respective input signals and output signals, and do not represent the actual operational relationship between the signals. The actual values ​​and variation amplitudes of each signal can be set according to the parameters and requirements of the actual application circuit.

[0023] The duty cycle control circuit 203 receives the voltage regulation signal Vc and outputs a switch control signal PWM based on the voltage regulation signal Vc. The switch control signal PWM is provided to the switch conversion circuit 21 to control the on / off state of the switch in the switch conversion circuit 21.

[0024] The duty cycle of the switching control signal PWM is the ratio of the duration during which the input voltage terminal provides energy to the energy storage element in the switching conversion circuit 21 to the duration of the switching cycle within one switching cycle. It can also be defined as the ratio of the on-time of the main power switch in the switching conversion circuit 21 to the duration of the switching cycle. When the main power switch is on, the energy storage element stores energy. In one embodiment, the duty cycle of the switching control signal PWM increases as the voltage regulation signal Vc increases and decreases as the voltage regulation signal Vc decreases.

[0025] In one embodiment, the switching circuit 21 includes a BOOST circuit. The relationship between the input voltage VIN and the output voltage VOUT of the BOOST circuit is as follows: VOUT = VIN / (1-D), where D represents the duty cycle of the switching control signal PWM. When the input voltage VIN experiences a step increase, the feedforward signal Vif increases simultaneously, pulling the voltage regulation signal Vc low, thereby rapidly reducing the duty cycle D of the switching control signal PWM and stabilizing the value of the output voltage VOUT. Similarly, when the input voltage VIN experiences a step decrease, the feedforward signal Vif decreases simultaneously, pulling the voltage regulation signal Vc high, thereby rapidly increasing the duty cycle D of the switching control signal PWM and stabilizing the value of the output voltage VOUT.

[0026] In one embodiment, the switching circuit 21 includes a BUCK circuit. The relationship between the input voltage and the output voltage VOUT of the BUCK circuit is as follows: VOUT = VIN × D, where D represents the duty cycle of the switching control signal PWM. When the input voltage VIN experiences a step increase, the feedforward signal Vif increases simultaneously, pulling the voltage regulation signal Vc low, thereby rapidly reducing the duty cycle D of the switching control signal PWM and stabilizing the value of the output voltage VOUT. Simultaneously, when the input voltage VIN experiences a step decrease, the feedforward signal Vif decreases simultaneously, pulling the voltage regulation signal Vc high, thereby rapidly increasing the duty cycle D of the switching control signal PWM and stabilizing the value of the output voltage VOUT.

[0027] It should be understood that the switching circuit 21 may also include other circuits that achieve energy transfer through the combined action of a switch and an energy storage element, such as a BUCK-BOOST circuit.

[0028] In some embodiments, the feedforward signal Vif is a voltage divider of the input voltage VIN. In some embodiments, the input voltage VIN is relatively small, in which case the feedforward signal Vif is essentially the same as the input voltage VIN.

[0029] exist Figure 2 In this embodiment, the adjustment amount of the voltage regulation signal Vc is simultaneously related to the current feedback signal Ifb. The current feedback signal Ifb represents the output current IOUT and is obtained by detecting the value of the output current IOUT. Any circuit or method for detecting the output current IOUT can be used in this invention, such as a current mirror circuit or a resistor connected in series with the load RL. It should be understood that the current feedback signal Ifb can be either a voltage signal or a current signal. When the current feedback signal Ifb is a voltage signal, its voltage value is related to the value of the output current IOUT. In one embodiment, the value of the current feedback signal Ifb increases as the output current IOUT increases and decreases as it decreases.

[0030] Ideally, the change in input voltage VIN should match the adjustment of the voltage regulation signal Vc. However, in reality, under different load conditions (i.e., different output currents IOUT), the change in input voltage VIN does not correspond to the adjustment of the voltage regulation signal Vc. Under light load conditions (i.e., when the output current IOUT is small, for example, with a first value IOUT1), assuming the change in input voltage VIN is V1, the required adjustment of the voltage regulation signal Vc is the first adjustment value Vc1. Under heavy load conditions (i.e., when the output current IOUT is large, for example, with a second value IOUT2, where IOUT2 ​​> IOUT1), assuming the change in input voltage VIN is also V1, the required adjustment of the voltage regulation signal Vc is the second adjustment value Vc2, and Vc1 > Vc2. In other words, the adjustment of the voltage regulation signal Vc is inconsistent under different load conditions. If the voltage regulation signal Vc is adjusted solely based on the input voltage VIN, the compensation effect for transient changes in input voltage VIN will be poor under certain load conditions. To eliminate this effect, Figure 2 In this embodiment, the current feedback signal Ifb, characterizing the output current IOUT, is added to the regulation circuit 204. Figure 2 In this embodiment, the difference between the feedforward signal Vif and the current feedback signal Ifb adjusts the voltage regulation signal Vc. That is, compared to a heavy load, under a light load condition, i.e., when the output current IOUT and the corresponding current feedback signal Ifb are smaller, the same input voltage change ∆VIN will produce a larger adjustment amount ∆Vc in the voltage regulation signal Vc.

[0031] Figure 3 This is a schematic diagram of the circuit structure of a switching power supply 300 according to an embodiment of this application. Figure 3As shown, the switching power supply 300 includes a switching conversion circuit 21 and its control circuit 32. The switching conversion circuit 21 has been described in detail above and will not be repeated here. The control circuit 32 includes a feedback circuit 302, an adjustment circuit 304, and a duty cycle control circuit 303.

[0032] exist Figure 3 In this embodiment, the feedback circuit 302 includes a voltage divider circuit with voltage divider resistors R1 and R2 and an error amplifier circuit EA1. The voltage divider resistors R1 and R2 divide the output voltage VOUT to generate a voltage divider signal VFB. One input of the error amplifier circuit EA1 receives the voltage divider signal VFB, and the other input receives a reference signal Vref. Based on the difference between the voltage divider signal VFB and the reference signal Vref, it provides a voltage feedback signal Vof. Figure 3 In the embodiment, the voltage feedback signal Vof decreases as the output voltage VOUT increases, and increases as the output voltage VOUT decreases.

[0033] The regulation circuit 304 includes a regulation transistor M1, a regulation resistor Rs, and a controlled current source Is. The regulation transistor M1, the regulation resistor Rs, and the controlled current source Is are connected in series between the power supply voltage VDD and the reference ground GND. The controlled current source Is provides a current I1 flowing through the regulation resistor Rs. The control terminal of the regulation transistor M1 receives a voltage feedback signal Vof, with its first terminal coupled to the power supply voltage VDD and its second terminal coupled to the first terminal of the regulation resistor Rs. The second terminal of the regulation resistor Rs is coupled to one terminal of the controlled current source Is, and the other terminal of the controlled current source Is is coupled to the reference ground GND. The second terminal of the regulation resistor Rs provides a voltage regulation signal Vc. Figure 3In this embodiment, the voltage regulation signal Vc can be expressed as Vc = Vof - Vgs - I1 × Rs. When the input voltage VIN increases, the feedforward signal Vif increases accordingly, the current I1 of the controlled current source Is increases, and the voltage regulation signal Vc decreases, thereby reducing the duty cycle of the switching control signal PWM and stabilizing the output voltage VOUT. When the input voltage VIN decreases, the feedforward signal Vif decreases accordingly, the current I1 of the controlled current source Is decreases, and the voltage regulation signal Vc increases, thereby increasing the duty cycle of the switching control signal PWM and stabilizing the output voltage VOUT. Simultaneously, the current I1 of the controlled current source Is is also controlled by the current feedback signal Ifb. The larger the current feedback signal Ifb, the smaller the current I1 of the controlled current source Is, and vice versa. For the same input voltage VIN change ∆VIN, when the current feedback signal Ifb is large, the change in current I1 of the controlled current source Is is small, resulting in a smaller adjustment ∆Vc of the voltage regulation signal Vc. Conversely, when the current feedback signal Ifb is small, the change in current I1 of the controlled current source Is is large, resulting in a larger adjustment ∆Vc of the voltage regulation signal Vc. In other words, the current feedback signal Ifb participates in adjusting the voltage regulation signal Vc, thus generating different adjustment ∆Vc of the voltage regulation signal Vc under different load conditions based on the same input voltage VIN change ∆VIN. This allows for better transient compensation over a wide load range.

[0034] exist Figure 3 In this embodiment, the positions of the regulating transistor M1, regulating resistor Rs, and controlled current source Is in the regulating circuit 304 can be interchanged. For example, if the positions of the regulating transistor M1 and regulating resistor Rs are interchanged, only the value of the voltage feedback signal Vof needs to be adjusted accordingly. Similarly, the positions of the regulating resistor Rs and the controlled current source Is can also be interchanged. In this case, the voltage regulation signal Vc increases as the current I1 output by the controlled current source Is increases, and decreases as the current I1 output by the controlled current source Is decreases. Therefore, the correspondence between the feedforward voltage Vif and the current feedback signal Ifb and the current I1 of the controlled current source Is can be changed. For example, as the feedforward voltage Vif increases, the current I1 of the controlled current source Is decreases, and vice versa. In one embodiment, when the positions of the regulating resistor Rs and the controlled current source Is are interchanged, the same effect can be achieved by changing the relationship between the switching control signal PWM and the voltage regulation signal Vc. Figure 2 The objective of this embodiment is to achieve the following: It should be understood that the embodiments of this application realize the generation of different voltage regulation signals Vc under different load conditions for the same change in input voltage VIN, thereby achieving the function of fast and stable compensation for transient changes in input voltage VIN over a wide load range.

[0035] The duty cycle control circuit 303 includes a comparator circuit CMP1. One end of the comparator circuit CMP1 receives a voltage regulation signal Vc, and the other end receives a triangular wave signal Vslope. Based on the comparison between the voltage regulation signal Vc and the triangular wave signal Vslope, it outputs a switch control signal PWM. The switch control signal PWM is provided to the switch conversion circuit 21 to control the on / off state of the switch in the switch conversion circuit 21.

[0036] Figure 4 This is a schematic diagram of the circuit structure of a controlled current source 400 according to an embodiment of this application. The controlled current source 400 can be used in... Figure 3 The switching power supply 300 of this embodiment includes a controlled current source 400 comprising an error amplifier circuit EA2, a current mirror circuit 401, and a resistor Ra. The non-inverting input of the error amplifier circuit EA2 receives the difference between the feedforward signal Vif and the current feedback signal Ifb, while the inverting input is coupled to the output of the error amplifier circuit EA2. The resistor Ra is coupled to the output of the error amplifier circuit EA2. The current flowing through the resistor Ra is proportional to the difference between the feedforward signal Vif and the current feedback signal Ifb. After passing through the current mirror circuit 401, the current flowing through the resistor Ra generates a current I1 proportional to this current. Therefore, the current I1 is proportional to the difference between the feedforward signal Vif and the current feedback signal Ifb. It should be understood that the difference between the feedforward signal Vif and the current feedback signal Ifb mentioned here does not refer to the arithmetic difference between the feedforward signal Vif and the current feedback signal Ifb, but only represents the influence of both the feedforward signal Vif and the current feedback signal Ifb on the value of the current I1. For example, under the same feedforward signal Vif, a larger current feedback signal Ifb results in a smaller current I1, and vice versa.

[0037] The input current of the current mirror circuit 401 is the current flowing through resistor Ra, and the output current is a current I1 that is proportional to the input current. Figure 4 In this embodiment, the current mirror circuit 401 acts as a current source at its output terminal Tc. It should be understood that the current mirror circuit 401 can also achieve the following: Figure 3 The current sink shown in the embodiment provides current in the opposite direction. It should be understood that both the current source and the current sink are current source circuits, only indicating structures with different current directions. Providing current in different directions by changing the structure of the current mirror circuit 401 is well known to those skilled in the art and will not be elaborated here.

[0038] Figure 5 This is a schematic diagram of the circuit structure of a controlled current source 500 according to an embodiment of this application. The controlled current source 500 can be used in... Figure 3The embodiment includes a switching power supply 300. The controlled current source 500 includes an error amplifier circuit EA3, a current mirror circuit 401, and a resistor Ra. The error amplifier circuit EA3 has a non-inverting input terminal to receive a feedforward signal Vif, a first inverting input terminal coupled to the output terminal To of the error amplifier circuit EA3, and a second inverting input terminal to receive a current feedback signal Ifb. Figure 5 As shown, the error amplifier circuit EA3 includes a non-inverting input transistor P1, a first inverting input transistor P2, a second inverting input transistor P3, load transistors N1 and N2, and a subsequent stage circuit 501. The control terminal of the non-inverting input transistor P1 receives a feedforward signal Vif, the control terminal of the first inverting input transistor P2 is coupled to the output terminal To, and the control terminal of the second inverting input transistor P3 receives a current feedback signal Ifb. Through the non-inverting input transistor P1 and the second inverting input transistor P3, the feedforward signal Vif and the current feedback signal Ifb jointly control the input of the error amplifier circuit EA3. The difference between the current of the non-inverting input transistor P1 and the sum of the currents of the first inverting input transistor P2 and the second inverting input transistor P3 is transmitted to the subsequent stage circuit 501 of the error amplifier circuit EA3 through a current mirror load circuit formed by the load transistors N1 and N2. The subsequent stage circuit 501 may include the output stage circuit of an error amplifier well known to those skilled in the art, or a combination of an intermediate stage circuit and an output stage circuit. In the error amplifier circuit EA3, if the current feedback signal Ifb remains constant: when the feedforward signal Vif increases, the voltage at the output terminal To increases accordingly, the current flowing through the resistor Ra increases, and the current I1 output by the controlled current source 500 through the current mirror circuit 401 increases; when the feedforward signal Vif decreases, the voltage at the output terminal To decreases accordingly, the current flowing through the resistor Ra decreases, and the current I1 output by the controlled current source 500 through the current mirror circuit 401 decreases. However, when the change in the feedforward signal Vif is the same: if the value of the current feedback signal Ifb is relatively large, the current of the second inverting input transistor P3 is relatively small, and therefore the voltage change at the output terminal To is relatively small; if the value of the current feedback signal Ifb is relatively small, the current of the second inverting input transistor P3 is relatively large, and therefore the voltage change at the output terminal To is relatively large. Thus, under light load, a larger adjustment of the current I1 can be achieved, thereby enabling a larger adjustment of the voltage regulation signal Vc under light load for the same input voltage VIN transition.

[0039] Figure 6 This is a schematic diagram of the circuit structure of a controlled current source 600 according to an embodiment of this application. The controlled current source 600 can be used in... Figure 3The switching power supply 300 of this embodiment includes a controlled current source 600 comprising an error amplifier circuit EA4, a current mirror circuit 401, and a resistor Ra. The error amplifier circuit EA4 has a non-inverting input terminal receiving a feedforward signal Vif, and an inverting input terminal coupled to an output terminal To. The error amplifier circuit EA4 includes a non-inverting input transistor P1, an inverting input transistor P2, load transistors N1 and N2, a bias current source Im, and a subsequent stage circuit 501. The control terminal of the non-inverting input transistor P1 receives the feedforward signal Vif, and the control terminal of the inverting input transistor P2 is coupled to the output terminal To. The bias current source Im is coupled to the bias terminal Tb, i.e., the connection point of the non-inverting input transistor P1 and the load transistor N1, and provides a bias current I2 controlled by a current feedback signal Ifb to the bias terminal Tb. The other ends of the non-inverting input transistor P1 and the inverting input transistor P2 are connected together to form a common terminal. The feedforward signal Vif controls the non-inverting input of the error amplifier circuit EA3 through the non-inverting input transistor P1. The bias current I2 provides bias to the bias terminal Tb. The difference between the bias current I2 and the non-inverting input transistor P1 is input to the load transistor N1. The difference between the current of the non-inverting input transistor P1 and the bias current I2, and then the difference between the non-inverting input transistor P2, is transmitted to the subsequent circuit 501 of the error amplifier circuit EA4. In the error amplifier circuit EA4, if the current feedback signal Ifb remains constant: when the feedforward signal Vif increases, the voltage at the output terminal To increases accordingly, the current flowing through the resistor Ra increases, and the current I1 output by the controlled current source 600 increases through the current mirror circuit 401; when the feedforward signal Vif decreases, the voltage at the output terminal To decreases accordingly, the current flowing through the resistor Ra decreases, and the current I1 output by the controlled current source 600 decreases through the current mirror circuit 401. When the change amplitude of the current feedback signal Vif is the same: if the value of the current feedback signal Ifb is relatively large, the bias current I2 is relatively large, and therefore the voltage change amplitude at the output terminal To is relatively small; if the value of the current feedback signal Ifb is relatively small, the bias current I2 is relatively small, and therefore the voltage change amplitude at the output terminal To is relatively large. This allows for a larger adjustment of the current I1 under light load conditions, and consequently, for the same input voltage VIN, a larger adjustment of the voltage regulation signal Vc under light load conditions.

[0040] In some embodiments, the bias current source Im can be configured to bias the current of the inverting input transistor P2. For example, the bias current Im can be configured to inject bias current I2 into the inverting input transistor P2 and its drain terminal, i.e., the connection terminal with the load transistor N2. In some embodiments, the bias current Im can also provide current to the bias terminal Tb instead of drawing current.

[0041] It should be understood that the high and low levels or trends of the signals in the above embodiments are set to match the type of transistor in the embodiments. In other embodiments, when the transistor type changes, the level form and trend of the corresponding control signal will also change accordingly.

[0042] Figure 7 This is a schematic flowchart of a switching power supply control method 700 according to an embodiment of this application. The control method 700 can be used to control the switching power supplies of the embodiments of this application, such as switching power supply 200 and switching power supply 300.

[0043] The control method 700 includes: step 701, providing a feedforward signal based on the input voltage of the switching power supply; step 702, providing a current feedback signal based on the output current of the switching power supply; step 703, providing a voltage feedback signal based on the output voltage of the switching power supply; step 704, providing a voltage regulation signal based on the feedforward signal, the current feedback signal, and the voltage feedback signal; and step 705, providing a switch control signal based on the voltage regulation signal to control the on / off state of the switch in the switching conversion circuit of the switching power supply. There is no sequential relationship between steps 701-703.

[0044] In one embodiment, the duty cycle of the switch control signal increases as the voltage regulation signal increases and decreases as the voltage regulation signal decreases.

[0045] In one embodiment, the voltage regulation signal increases as the voltage feedback signal increases and decreases as the voltage feedback signal decreases. In another embodiment, the voltage feedback signal is an amplified error signal between the reference voltage and the output voltage of the switching power supply, and decreases as the output voltage of the switching power supply increases and increases as the output voltage decreases.

[0046] In one embodiment, step 704 includes: providing a feedforward adjustment signal based on a feedforward signal and a current feedback signal; providing a voltage adjustment signal based on a feedforward adjustment signal and a voltage feedback signal; wherein the feedforward adjustment signal increases as the feedforward signal increases and decreases as the feedforward signal decreases, and decreases as the current feedback signal increases and increases as the current feedback signal decreases.

[0047] In one embodiment, the voltage regulation signal decreases as the feedforward signal increases, and increases as the feedforward signal decreases.

[0048] In one embodiment, the same change in the feedforward signal has a greater effect on the voltage regulation signal under light load than under heavy load. That is, as the output current of the switching power supply decreases, the adjustment of the voltage regulation signal corresponding to the change in the feedforward signal increases.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any way. Although this application has disclosed preferred embodiments above, it is not intended to limit the application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.

Claims

1. A control circuit for a switching circuit, comprising: The regulating circuit receives a voltage feedback signal characterizing the switching circuit, a current feedback signal characterizing the output current of the switching circuit, and a feedforward signal characterizing the input voltage, and outputs a voltage regulating signal based on the voltage feedback signal, the current feedback signal, and the feedforward signal. as well as The duty cycle control circuit receives the voltage regulation signal and, based on the voltage regulation signal, outputs a switch control signal to the switch conversion circuit to control the output voltage or output current of the switch conversion circuit. The voltage regulation signal decreases as the feedforward signal increases, and increases as the feedforward signal decreases. When the output current of the switching power supply has a first value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is the first regulation amount. When the output current of the switching power supply has a second value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is the second regulation amount. The first value is less than the second value, and the first regulation amount is greater than the second regulation amount.

2. The control circuit as described in claim 1 further includes: The feedback circuit is based on the output voltage of the switching circuit and the output voltage feedback signal. The feedback circuit includes an error amplifier circuit.

3. The control circuit as described in claim 1, wherein the adjustment circuit comprises: A first regulating circuit, based on the current feedback signal and the feedforward signal, outputs a feedforward regulating signal, wherein the feedforward regulating signal increases as the feedforward signal increases and decreases as the feedforward signal decreases, and the feedforward regulating signal decreases as the current feedback signal increases and increases as the current feedback signal decreases; and The second adjustment circuit outputs a voltage adjustment signal based on the feedforward adjustment signal and the voltage feedback signal. The voltage adjustment signal increases as the voltage feedback signal increases and decreases as the voltage feedback signal decreases. The voltage adjustment signal decreases as the feedforward adjustment signal increases and increases as the feedforward adjustment signal decreases.

4. The control circuit as claimed in claim 1, wherein the adjustment circuit comprises: Adjusting the transistor; Adjust the resistance; as well as Controlled current source; The regulating transistor, regulating resistor, and controlled current source are connected in series between the power supply voltage and the reference ground. The controlled current source provides a regulating current flowing through the regulating resistor. One end of the regulating resistor generates a voltage regulation signal. The feedforward signal and the current feedback signal control the current of the controlled current source.

5. The control circuit as described in claim 4, wherein the controlled current source comprises: An error amplifier circuit has a non-inverting input terminal that receives the feedforward signal and the voltage regulation signal, and an inverting input terminal and an output terminal that are coupled together. A current mirror circuit has an input terminal coupled to the output terminal of the error amplifier circuit and an output terminal that provides current. as well as A resistor is coupled between the input terminal of the current mirror circuit and the reference ground.

6. The control circuit of claim 4, wherein the controlled current source comprises: An error amplifier circuit includes a non-inverting input transistor, a first inverting input transistor, and a second inverting input transistor. The control terminal of the non-inverting input transistor receives the feedforward signal. The control terminal of the first inverting input transistor is coupled to the output terminal of the error amplifier circuit, and the control terminal of the second inverting input transistor receives the current feedback signal. A current mirror circuit has an input terminal coupled to the output terminal of the error amplifier circuit and an output terminal that provides an adjustment current. as well as A resistor is coupled between the input terminal of the current mirror circuit and the reference ground.

7. The control circuit of claim 4, wherein the controlled current source comprises: An error amplifier circuit includes a non-inverting input transistor, an inverting input transistor, and a bias current source, wherein the control terminal of the non-inverting input transistor receives the feedforward signal, the control terminal of the inverting input transistor is coupled to the output terminal of the error amplifier circuit, and the bias current source is coupled to one of the non-inverting input transistor or the inverting input transistor.

8. A switching power supply, comprising the control circuit as described in claims 1-7, and further comprising a switch conversion circuit, the switch conversion circuit comprising at least one switch, the on / off state of the switch being controlled by the switch control signal.

9. The switching power supply of claim 8, wherein, The switching circuit has a BUCK topology, BOOST topology, or BUCK-BOOST topology.

10. A control method for a switching power supply, comprising: The input voltage of the switching power supply provides the feedforward signal; Provide current feedback signal based on the output current of the switching power supply; Provide voltage feedback signal based on the output voltage of the switching power supply; Voltage regulation signals are provided based on feedforward signals, current feedback signals, and voltage feedback signals; as well as The switching control signal is provided based on the voltage regulation signal to control the on / off state of the switch in the switching conversion circuit of the switching power supply; The voltage regulation signal decreases as the feedforward signal increases, and increases as the feedforward signal decreases. When the output current of the switching power supply has a first value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is the first regulation amount. When the output current of the switching power supply has a second value, the regulation amount of the voltage regulation signal corresponding to the change in the feedforward signal is the second regulation amount. The first value is less than the second value, and the first regulation amount is greater than the second regulation amount.

11. The control method as described in claim 10, wherein: The duty cycle of the switch control signal increases as the voltage regulation signal increases and decreases as the voltage regulation signal decreases.

12. The control method as described in claim 10, wherein: The voltage feedback signal is an amplified error signal between the reference voltage and the output voltage of the switching power supply, and it decreases as the output voltage of the switching power supply increases, and increases as the output voltage decreases; and The voltage regulation signal increases as the voltage feedback signal increases, and decreases as the voltage feedback signal decreases.

13. The control method of claim 10, wherein providing the voltage regulation signal based on the feedforward signal, the current feedback signal, and the voltage feedback signal comprises: The feedforward adjustment signal is provided based on the feedforward signal and the current feedback signal; as well as The voltage regulation signal is provided based on the feedforward regulation signal and the voltage feedback signal; The feedforward adjustment signal increases as the feedforward signal increases and decreases as the feedforward signal decreases, and decreases as the current feedback signal increases and increases as the current feedback signal decreases.

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