CN114649935A - Switch converter and control circuit thereof - Google Patents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
Abstract
The application discloses a switching converter and a control circuit thereof. The control circuit includes: the hysteresis voltage control circuit generates a hysteresis voltage according to a first feedback signal of the direct-current output voltage; the PWM comparator compares a second feedback signal of the direct-current output voltage and a superposed signal of the ripple signal with the hysteresis voltage to generate a pulse width modulation signal; and the logic and driving circuit converts the pulse width modulation signal into a switch control signal to control the conducting state of at least one switching tube, so that the switch converter can adaptively change the size of a hysteresis window according to the direct current output voltage, and the range of frequency stability is widened.
Description
Technical Field
The present invention relates to the field of switching power supply technologies, and in particular, to a switching converter and a control circuit thereof.
Background
Switching converters have been widely used in electronic systems for generating the operating voltages and currents required by internal circuit modules or loads. The switching converter adopts a power switch tube to control the transmission of electric energy from an input end to an output end, so that constant output voltage and/or output current can be provided at the output end. In a switching converter, a ripple-based constant on-time control method evolved from a hysteresis mode has the advantages of constant system frequency, good light-load efficiency, fast transient response and easy implementation, and thus has been widely used in recent years.
Fig. 1 shows a schematic circuit diagram of a switching converter with a fixed hysteresis control mode and a constant on-time control mode according to the prior art. The switching converter 100 comprises a main power circuit and a control circuit, wherein the main power circuit comprises a switching tube MD1 and a switching tube MD2 which are connected between an input end and a grounding end in series, an inductor Lx is connected between an intermediate node of the switching tube MD1 and the switching tube MD2 and an output end, and an output capacitor Cout is connected between the output end and the grounding end. The resistor Resr is an equivalent series resistor of the output capacitor Cout, and the load RL is connected in parallel between two ends of the output capacitor Cout. The switching converter 100 has an input terminal receiving a dc input voltage Vin and an output terminal providing a dc output voltage Vout. The control circuit of switching converter 100 is used to provide switching control signals to switching transistors MD1 and MD 2.
In the control circuit of the switching converter 100, the on-time control circuit 110 sets the on-time Ton1 of the switching period Tsw, thereby generating a reset signal. The minimum off-time control circuit 120 sets a minimum off-time Toff _ min (or a maximum switching frequency) corresponding to a predetermined output voltage and a predetermined load. The error amplifier EA obtains an error signal Vcomp according to the first feedback signal FB1 of the dc output voltage Vout and the reference voltage Vref, and the PWM comparator 130 compares the error signal Vcomp with a superimposed signal of the Ripple signal Ripple and the second feedback signal FB2 to obtain the pulse width modulation signal PWM. The logic and driving circuit 140 converts the pulse width modulation signal PWM into a switching control signal to control the conduction state of the switching tubes MD1 and MD 2. The Ripple injection circuit 150 is used for providing the Ripple signal Ripple.
In fig. 1, the output of the PWM comparator 130 determines the on and off of the switching transistors MD1 and MD2, and the on-time control circuit 110 and the off-time control circuit 120 limit the minimum on-time and the minimum off-time of the switching transistors. When the on-time Ton determined by the PWM signal PWM is greater than the on-time Ton1, the switching converter 100 operates in the hysteretic control mode; when the on-time Ton determined by the PWM signal PWM is less than the on-time Ton1, the switching converter 100 operates in the adaptive on-time control mode. However, when the off-time Toff determined by the PWM signal PWM is less than the minimum off-time Toff _ min, the off-time of the switching tube is determined by the minimum off-time Toff _ min, and since the PWM comparator 130 always turns on the switching tube in advance in this state, the system cannot operate in DCM (Discontinuous Conduction Mode) in this state, which greatly reduces the light-load efficiency of the system.
In order to solve this problem, the switching converter of the prior art sets the off-time Toff of the pulse width modulation signal PWM to be always greater than the minimum off-time Toff _ min, because the off-time of the pulse width modulation signal PWM is:
where Vhys represents the hysteresis voltage of the PWM comparator 130, Vout represents the DC output voltage, R5Represents the resistance value, C, of the resistor R5 in the ripple injection circuit 1501Representing the capacitance value of the capacitor C1 in the ripple injection circuit 150. Assuming that the minimum off-time Toff _ min is 50ns, it can be obtained that the existing switching converter needs to satisfy:
taking the dc output voltage Vout at 0.5V to 4V as an example, in order to satisfy the above conditions, the switching converter of the prior art needs to ensure that equation 2 is satisfied when the dc output voltage Vout is 4V, so that the hysteresis voltage of the PWM comparator 130 of the prior art needs to be satisfied:
in order to ensure that the system has a certain margin, the hysteresis voltage Vhys of the PWM comparator 130 is set to 80 mV. The on-time determined by the PWM signal PWM is:
further, since the on-time Ton1 is D × Tsw is D × 500ns, where D is the duty ratio of the switching control signal, and Tsw is 500ns and RC is 5us in the case of a 2MHz switching converter, the switching points of the hysteresis control mode and the adaptive on-time control mode of the switching converter 100 in the prior art can be obtained as follows:
in order to find the following formula 5:
vin × D × (1-D) >10 × Vhys formula 6
Substituting Vhys to 80mV into equation 6 results in the switching converter 100 operating in the adaptive on-time control mode when Vin × D × (1-D) >0.8V, and operating in the hysteretic control mode when Vin × D × (1-D) < 0.8V.
Fig. 2 is a graph illustrating switching points of a switching converter of the prior art at different input voltages. For ease of understanding, equation 6 is plotted as a graph shown in fig. 2, where the horizontal axis represents duty ratio D, the vertical axis represents Vin × D × (1-D), the various curves represent plots of switching points at different input voltages, the dashed line represents the mode switching point for a prior art switching converter, above the dashed line the switching converter 100 operates in the adaptive on-time control mode (ACOT), and below the dashed line the switching converter 100 operates in the hysteretic control mode (HYS). As shown in fig. 2, in the conventional switching converter, the smaller the input voltage Vin, the smaller the operating range of the adaptive on-time mode, for example, when the input voltage Vin is 3V, the switching converter 100 operates in the hysteretic control mode in the whole output range, so that the conventional switching converter has a problem of large frequency variation range under low input voltage, which reduces the system stability and light-load efficiency.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a switching converter and a control circuit thereof, which solve the problem of a conventional switching converter that the frequency variation range is large under a low input voltage.
According to an aspect of the embodiments of the present invention, there is provided a control circuit of a switching converter, the switching converter controlling power transmission from an input end to an output end by using at least one switching tube so as to generate a dc output voltage according to a dc input voltage, wherein the control circuit includes: the hysteresis voltage control circuit generates a hysteresis voltage according to a first feedback signal of the direct-current output voltage; the PWM comparator compares a second feedback signal of the direct current output voltage and a superposed signal of a ripple signal with the hysteresis voltage to generate a pulse width modulation signal; and the logic and drive circuit converts the pulse width modulation signal into a switch control signal to control the conduction state of the at least one switching tube, wherein the hysteresis voltage control circuit adaptively adjusts the hysteresis voltage according to the direct-current output voltage so as to stabilize the switching frequency.
Optionally, the control circuit further includes: and the logic and driving circuit controls the switch converter to work in a hysteresis control mode or a self-adaptive on-time control mode according to the comparison result of the on-time of the pulse width modulation signal and the first on-time.
Optionally, the control circuit further includes: and the minimum turn-off time control circuit is used for generating minimum turn-off time, and the turn-off time determined by the pulse width modulation signal is greater than the minimum turn-off time.
Optionally, the control circuit further includes: a ripple injection circuit for generating the ripple signal.
Optionally, the logic and driver circuit is configured to: and controlling the switch converter to work in an adaptive on-time control mode under the condition that the on-time of the pulse width modulation signal is less than the first on-time, and controlling the switch converter to work in a hysteresis control mode under the condition that the on-time of the pulse width modulation signal is greater than the first on-time.
Optionally, the hysteresis voltage control circuit includes: the inverting input end and the non-inverting input end of the error amplifier respectively receive the first feedback signal and the first reference voltage, and the output end of the error amplifier is used for providing an error signal; a transconductance amplifier, wherein an inverting input terminal and a non-inverting input terminal respectively receive a second reference voltage and the error signal, and an output terminal is used for providing the hysteresis voltage; a first resistor and a second resistor connected in series between the output terminal of the transconductance amplifier and ground; and a first transistor, wherein a first end of the first transistor is connected to the middle node of the first resistor and the second resistor, a second end of the first transistor is grounded, and a control end of the first transistor receives the pulse width modulation signal.
Optionally, the hysteresis voltage control circuit further includes: and the compensation resistor and the compensation capacitor are sequentially connected between the output end of the error amplifier and the ground.
Optionally, a proportionality coefficient between the hysteresis voltage and the dc output voltage is adjusted by setting a proportionality ratio between the first resistor and the second resistor.
According to another aspect of an embodiment of the present invention, there is provided a switching converter including: the main power circuit adopts at least one switching tube to control the electric energy transmission from the input end to the output end, so as to generate direct current output voltage according to the direct current input voltage; and the control circuit is used for generating a switch control signal to control the conduction state of the at least one switching tube.
Optionally, the main power circuit adopts a topology selected from any one of the following: the power supply comprises a floating type Buck power circuit, a solid type Buck power circuit, a flyback power circuit, a Buck-Boost type power circuit and a Boost type power circuit.
The switch converter and the control circuit thereof in the embodiment of the invention comprise the hysteresis voltage control circuit which generates the hysteresis voltage in a self-adaptive manner according to the direct current output voltage, so that the switch converter can change the size of a hysteresis window in a self-adaptive manner according to the direct current output voltage, and the range of stable frequency is widened.
Furthermore, the switching converter of the embodiment of the invention reserves the advantages of fast transient response and high light load efficiency of the system in the hysteresis control mode, improves the problem of large frequency change range of the hysteresis control mode, and is beneficial to improving the frequency stability and the light load efficiency of the system.
Furthermore, the switching converter of the embodiment of the invention can enlarge the range of the switching converter working in the self-adaptive on-time control mode, thereby enlarging the range of constant system frequency and being beneficial to improving the system stability and light load efficiency. In addition, the switching converter of the embodiment of the invention can adjust the mode switching point by setting the proportionality coefficient generated by the adaptive hysteresis voltage, thereby being capable of adapting to different modes of the switching converter and reducing the design cost and the manufacturing cost of redesigning the control circuit for different types of switching converters.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 shows a schematic circuit diagram of a switching converter according to the prior art;
FIG. 2 is a graph illustrating switching point curves of a prior art switching converter at different input voltages;
FIG. 3 shows a schematic circuit diagram of a switching converter according to an embodiment of the invention;
FIG. 4 illustrates an operational timing diagram of a switching converter operating in a hysteretic control mode, according to an embodiment of the present invention;
FIG. 5 illustrates an operational timing diagram of a switching converter operating in an adaptive on-time control mode, according to an embodiment of the present invention;
fig. 6 shows a schematic diagram of switching point curves of a switching converter according to an embodiment of the invention at different input voltages.
Detailed Description
Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown.
It should be understood that in the following description, a "circuit" refers to a conductive loop made up of at least one element or sub-circuit by electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.
In this application, the switching transistor is a transistor operating in a switching mode to provide a current path, and includes one selected from a bipolar transistor or a field effect transistor. The first end and the second end of the switching tube are respectively a high potential end and a low potential end on a current path, and the control end is used for receiving a driving signal to control the switching tube to be switched on and off. The present invention may be embodied in various forms, some examples of which are described below.
Fig. 3 shows a schematic circuit diagram of a switching converter according to an embodiment of the invention. The switching converter 200 adopts a Buck topology and works in a floating mode, and comprises a main power circuit and a control circuit, wherein the main power circuit comprises switching tubes MD1 and MD2 which are connected between an input end and a grounding end in series, an inductor Lx is connected between a middle node and an output end of the switching tubes MD1 and MD2, an output capacitor Cout is connected between the output end and the grounding end, a resistor Resr is an equivalent series resistor of the output capacitor Cout, and a load RL is connected between two ends of the output capacitor Cout in parallel. The switching converter 200 has an input terminal receiving a dc input voltage Vin and an output terminal providing a dc output voltage Vout. The voltage division network formed by the resistors R1 and R2 is used for obtaining a first feedback signal FB1 of the DC output voltage Vout, the voltage division network formed by the resistors R3 and R4 is used for obtaining a second feedback signal FB2 of the DC output voltage Vout, and the capacitor Cc is connected between two ends of the resistor R1 in parallel.
The control circuit of the switching converter 200 is used to provide switching control signals to the switching tubes MD1 and MD 2. The control circuit of the switching converter 200 includes an on-time control circuit 210, a minimum off-time control circuit 220, a hysteresis window control circuit 230, a PWM comparator 240, a logic and driving circuit 250, and a ripple injection circuit 260.
The on-time control circuit 210 sets a first on-time Ton1 of the switching period Tsw.
The minimum off-time control circuit 220 sets a minimum off-time Toff _ min (or a maximum switching frequency) corresponding to a predetermined output voltage and a predetermined load.
The hysteresis voltage control circuit 230 is used for adaptively generating a hysteresis voltage Vhys according to the dc output voltage Vout to stabilize the switching frequency. The first feedback signal FB1 of the dc output voltage Vout is inputted to the hysteresis voltage control circuit 230, and the hysteresis voltage control circuit 230 generates the hysteresis voltage Vhys according to the first feedback signal FB 1.
The Ripple injection circuit 260 is connected to the inductor Lx for providing a Ripple signal Ripple. Further, the ripple injection circuit 260 includes a resistor R5 and capacitors C1 and C2. A first end of the resistor R5 is connected to a first end of the inductor Lx, a second end of the resistor R5 is connected to a first end of the capacitor C1, a second end of the capacitor C1 is connected to a second end of the inductor Lx, a first end of the capacitor C2 is connected to a middle node between the resistor R5 and the capacitor C1, and a second end of the capacitor C2 is used for providing the Ripple signal Ripple.
The PWM comparator 240 compares the hysteresis voltage Vhys with a superimposed signal of the Ripple signal Ripple and the second feedback signal FB2 to obtain the pulse width modulation signal PWM.
The logic and driving circuit 250 generates a switch control signal according to the pulse width modulation signal PWM, the first on-time Ton1 and the minimum off-time Toff _ min to control the on-state of the switching tubes MD1 and MD 2. The switch control signal is a drive signal generated in accordance with a pulse width modulation signal. For example, the switching control signal of the switching tube MD1 is an in-phase signal of the pwm signal, and the switching control signal of the switching tube MD2 is an inverted signal of the pwm signal.
Further, the logic and driving circuit 250 controls the switching converter 200 to operate in the hysteretic control mode or the adaptive on-time control mode according to the comparison result between the on-time Ton determined by the PWM signal PWM and the first on-time Ton 1.
Fig. 4 and 5 show operation timing diagrams of the switching converter according to the embodiment of the present invention operating in the hysteretic control mode and the adaptive on-time control mode, respectively. Fig. 4 and 5 respectively show waveforms of the Ripple signal Ripple, the PWM signal PWM, the first on-time Ton1, the minimum off-time Toff _ min, and the switching signal SW from top to bottom.
As shown in fig. 4 and 5, the switching converter 200 according to the embodiment of the present invention can operate in the hysteretic control mode or the adaptive on-time control mode. When the on-time Ton determined by the PWM signal PWM is greater than the first on-time Ton1, the switching converter 200 operates in the hysteresis control mode, and the on-time of the switching tube MD1 is determined by the PWM signal PWM; when the on-time Ton determined by the PWM signal PWM is less than the first on-time Ton1, the switching converter 200 operates in the adaptive on-time control mode, and the turn-off time of the switching tube MD1 is determined by the first on-time Ton 1. The switching converter 200 of the embodiment of the invention reserves the advantages of fast transient response and high light load efficiency of the system in the hysteresis control mode, improves the problem of large frequency change range of the hysteresis control mode, and is beneficial to improving the frequency stability and the light load efficiency of the system.
In addition, since the off-time Toff of the switch tube is determined by the minimum off-time Toff _ min when the off-time Toff determined by the pulse width modulation signal PWM is smaller than the minimum off-time Toff _ min, and since the PWM comparator 230 always turns on the switch tube in advance in this state, the system cannot operate in DCM in this state, and the light load efficiency of the system is greatly reduced, the switch converter 200 according to the embodiment of the present invention needs to set the off-time Toff of the pulse width modulation signal PWM to be always greater than the minimum off-time Toff _ min.
With continued reference to fig. 3, the hysteresis voltage control circuit 230 includes an error amplifier EA, a transconductance amplifier 231, a transistor M1, and resistors R6 and R7. The inverting input terminal of the error amplifier EA receives the first feedback signal FB1, the non-inverting input terminal receives the first reference voltage Vref1, and the error amplifier EA is configured to obtain the error signal Vcomp according to the first feedback signal FB1 and the first reference voltage Vref 1. The non-inverting input terminal of the transconductance amplifier 231 receives the error signal Vcomp, the inverting input terminal receives the second reference voltage Vref2, and the output terminal is connected to the non-inverting input terminal of the PWM comparator 240 to output the hysteresis voltage Vhys. Resistors R6 and R7 are sequentially connected in series between the output terminal of the transconductance amplifier 231 and the ground, the transistor M1 is connected in parallel between the two terminals of the resistor R7, and the control terminal of the transistor M1 is connected to the output terminal of the PWM comparator 240.
Further, the hysteresis voltage control circuit 230 further includes a compensation network connected between the output terminal of the error amplifier EA and the ground, and the compensation network includes a compensation resistor Rea and a compensation capacitor Cea.
Fig. 6 is a schematic diagram showing a switching point curve of the switching converter according to the embodiment of the invention under different input voltages. From equation 6 above, the switching converter 200 operates in the adaptive on-time control mode when Vin × D × (1-D) >10 × Vhys, and the switching converter 100 operates in the hysteretic control mode when Vin × D × (1-D) < 10 × Vhys. In the embodiment of the present invention, the hysteresis voltage Vhys may be obtained by setting the hysteresis voltage control circuit 230 to K% × Vout, where K represents a proportionality coefficient, which is a constant. It can thus be seen that the switching converter 200 operates in the adaptive on-time control mode when D < 1-10 × K%, and the switching converter 200 operates in the hysteretic control mode when D > 1-10 × K%. By way of example, setting the scaling factor K to 2, it can be seen that when D < 80%, the switching converter 200 operates in the adaptive on-time control mode; when D > 80%, where D denotes the duty cycle of the pulse width modulation signal PWM, the switching converter 200 operates in the hysteretic control mode.
In fig. 6, the horizontal axis represents the duty ratio D, the vertical axis represents Vin × D × (1-D), the different curves represent graphs of switching points at different input voltages, the dotted line represents the mode switching points of the switching converter 200 according to the embodiment of the present invention, the left-hand side of the dotted line represents the operation in the adaptive on-time control mode (ACOT), and the right-hand side of the dotted line represents the operation in the hysteretic control mode (HYS). As can be seen from fig. 6, the switching converter according to the embodiment of the present invention can increase the range of the switching converter operating in the adaptive on-time control mode, thereby increasing the range of the system frequency constancy, and facilitating to improve the system stability and the light load efficiency. In addition, the switching converter of the embodiment of the invention can adjust the mode switching point by setting the proportional coefficient generated by the self-adaptive hysteresis voltage so as to meet different working conditions, and the application range is wider.
Further, the proportionality coefficient of the adaptive hysteresis voltage generation can be changed by setting the resistance ratio of the resistors R5 and R6. As shown in fig. 3, the transconductance amplifier 231 compares the error signal Vcomp with the second reference voltage Vref2, the output of the transconductance amplifier is provided to the non-inverting input terminal of the PWM comparator 240, the inverting input terminal of the PWM comparator 240 receives the superimposed signal of the Ripple signal Ripple and the second feedback signal FB2, and when the system operation is stable, it can obtain:
by setting the resistance values of the resistor R3 and the resistor R4 to 600K Ω and 400K Ω, respectively, it is possible to obtain:
and because:
where gm denotes the transconductance of the transconductance amplifier 231, and by setting R6/(R5+ R6) to 5% and gm x (R5+ R6) to 1, it is possible to obtain:
vhys is 5% × Vcomp equation 10
In combination, equation 8 and equation 10 can yield:
as can be seen from the above analysis, by setting the ratio of the resistances of the resistors R5 and R6, the ratio coefficient of the adaptive hysteresis voltage generation is changed, so as to adaptively adjust the mode switching point of the switching converter.
In summary, in the switching converter and the control circuit thereof according to the embodiments of the present invention, the control circuit includes the hysteresis voltage control circuit that generates the hysteresis voltage in a self-adaptive manner according to the dc output voltage, so that the switching converter can change the size of the hysteresis window in a self-adaptive manner according to the dc output voltage, thereby widening the range of frequency stability.
Furthermore, the switching converter of the embodiment of the invention reserves the advantages of fast transient response and high light load efficiency of the system in the hysteresis control mode, improves the problem of large frequency change range of the hysteresis control mode, and is beneficial to improving the frequency stability and the light load efficiency of the system.
Furthermore, the switching converter of the embodiment of the invention can enlarge the range of the switching converter working in the self-adaptive on-time control mode, thereby enlarging the range of constant system frequency and being beneficial to improving the system stability and light load efficiency. In addition, the switching converter of the embodiment of the invention can adjust the mode switching point by setting the proportionality coefficient generated by the adaptive hysteresis voltage, thereby being capable of adapting to different modes of the switching converter and reducing the design cost and the manufacturing cost of redesigning the control circuit for different types of switching converters.
In the above embodiments, although the switching converter with the Buck topology is described with reference to fig. 3, it is understood that the control circuit according to the embodiments of the present invention may also be used in switching converters with other topologies, and the structure of the main power circuit includes, but is not limited to, a floating-ground type Buck power circuit, a field type Buck power circuit, a flyback power circuit, a Buck-Boost type power circuit, a Boost type power circuit, and other topologies.
In the above description, well-known structural elements and steps are not described in detail. It should be understood by those skilled in the art that the corresponding structural elements and steps may be implemented by various technical means. In addition, in order to form the same structural elements, those skilled in the art may also design a method which is not exactly the same as the above-described method. In addition, although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in combination to advantage.
In accordance with the present invention, as set forth above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The scope of the invention should be determined from the following claims.
Claims (10)
1. A control circuit for a switching converter that uses at least one switching transistor to control the transfer of power from an input terminal to an output terminal to produce a dc output voltage from a dc input voltage, wherein the control circuit comprises:
the hysteresis voltage control circuit generates a hysteresis voltage according to a first feedback signal of the direct-current output voltage;
the PWM comparator compares a second feedback signal of the direct current output voltage and a superposed signal of a ripple signal with the hysteresis voltage to generate a pulse width modulation signal; and
a logic and drive circuit for converting the pulse width modulation signal into a switch control signal to control the conduction state of the at least one switching tube,
the hysteresis voltage control circuit adaptively adjusts the hysteresis voltage according to the direct current output voltage so as to stabilize the switching frequency.
2. The control circuit of claim 1, further comprising:
and the logic and driving circuit controls the switch converter to work in a hysteresis control mode or a self-adaptive on-time control mode according to the comparison result of the on-time of the pulse width modulation signal and the first on-time.
3. The control circuit of claim 1, further comprising:
and the minimum turn-off time control circuit is used for generating minimum turn-off time, and the turn-off time determined by the pulse width modulation signal is greater than the minimum turn-off time.
4. The control circuit of claim 1, further comprising:
a ripple injection circuit for generating the ripple signal.
5. The control circuit of claim 2, wherein the logic and drive circuit is configured to:
and controlling the switching converter to work in an adaptive on-time control mode under the condition that the on-time of the pulse width modulation signal is less than the first on-time, and controlling the switching converter to work in a hysteresis control mode under the condition that the on-time of the pulse width modulation signal is greater than the first on-time.
6. The control circuit of claim 1, wherein the hysteresis voltage control circuit comprises:
the inverting input end and the non-inverting input end of the error amplifier respectively receive the first feedback signal and the first reference voltage, and the output end of the error amplifier is used for providing an error signal;
a transconductance amplifier, wherein an inverting input terminal and a non-inverting input terminal respectively receive a second reference voltage and the error signal, and an output terminal is used for providing the hysteresis voltage;
a first resistor and a second resistor connected in series between the output terminal of the transconductance amplifier and ground; and
and the first end of the first transistor is connected to the middle node of the first resistor and the second resistor, the second end of the first transistor is grounded, and the control end of the first transistor receives the pulse width modulation signal.
7. The control circuit of claim 6, wherein the hysteresis voltage control circuit further comprises:
and the compensation resistor and the compensation capacitor are sequentially connected between the output end of the error amplifier and the ground.
8. The control circuit of claim 6, wherein a proportionality factor between the hysteresis voltage and the DC output voltage is adjusted by setting a proportionality of the first resistance and the second resistance.
9. A switching converter, comprising:
the main power circuit adopts at least one switching tube to control the electric energy transmission from the input end to the output end, so as to generate direct current output voltage according to the direct current input voltage; and
the control circuit according to any of claims 1-8, configured to generate a switch control signal to control the conducting state of the at least one switching tube.
10. The switching converter of claim 9, the main power circuit employing a topology selected from any one of: the power supply comprises a floating type Buck power circuit, a solid type Buck power circuit, a flyback power circuit, a Buck-Boost type power circuit and a Boost type power circuit.
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| CN202011492456.6A CN114649935A (en) | 2020-12-17 | 2020-12-17 | Switch converter and control circuit thereof |
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| CN202011492456.6A CN114649935A (en) | 2020-12-17 | 2020-12-17 | Switch converter and control circuit thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114924608A (en) * | 2022-06-23 | 2022-08-19 | 圣邦微电子(苏州)有限责任公司 | Reference voltage generating circuit |
| CN115242089A (en) * | 2022-07-15 | 2022-10-25 | 圣邦微电子（北京）股份有限公司 | Switch converter and control circuit and control method thereof |
| CN116094877A (en) * | 2023-04-11 | 2023-05-09 | 浙江地芯引力科技有限公司 | Differential signal transmission circuit and data transmission device |
| CN115242089B (en) * | 2022-07-15 | 2024-05-14 | 圣邦微电子（北京）股份有限公司 | Switching converter, control circuit and control method thereof |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101330261A (en) * | 2007-06-18 | 2008-12-24 | 天钰信息科技（上海）有限公司 | Switch power circuit |
| DE102008024090A1 (en) * | 2008-05-17 | 2009-11-26 | Moeller Gmbh | Switching regulator with PWM controller |
| CN103701322A (en) * | 2012-09-27 | 2014-04-02 | 三星电子株式会社 | Power supply circuit and hysteresis buck converter |
| TW201448437A (en) * | 2013-06-07 | 2014-12-16 | Richtek Technology Corp | Voltage converter controller, voltage converter circuit and control method for voltage converter circuit |
| CN105009435A (en) * | 2013-03-08 | 2015-10-28 | 高通股份有限公司 | Feed-forward frequency control method for current mode hysteretic buck regulator |
| WO2016095447A1 (en) * | 2014-12-15 | 2016-06-23 | 深圳市中兴微电子技术有限公司 | Frequency locking method and device for buck converter in hysteresis mode |
| CN105846678A (en) * | 2016-03-25 | 2016-08-10 | 东南大学 | Secondary-ring control system for single-inductor multiple-output switch power converter |
| CN108880249A (en) * | 2015-08-25 | 2018-11-23 | 华为技术有限公司 | Voltage conversion circuit, method and Multiphase Parallel power-supply system |
| CN111900878A (en) * | 2020-08-06 | 2020-11-06 | 深圳市凯冠智能科技有限公司 | Adaptive hysteresis control converter for enhancing transient characteristics, control method and equipment |
-
2020
- 2020-12-17 CN CN202011492456.6A patent/CN114649935A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101330261A (en) * | 2007-06-18 | 2008-12-24 | 天钰信息科技（上海）有限公司 | Switch power circuit |
| DE102008024090A1 (en) * | 2008-05-17 | 2009-11-26 | Moeller Gmbh | Switching regulator with PWM controller |
| EP2128969A2 (en) * | 2008-05-17 | 2009-12-02 | Moeller GmbH | Controller with PWM regulator |
| CN103701322A (en) * | 2012-09-27 | 2014-04-02 | 三星电子株式会社 | Power supply circuit and hysteresis buck converter |
| CN105009435A (en) * | 2013-03-08 | 2015-10-28 | 高通股份有限公司 | Feed-forward frequency control method for current mode hysteretic buck regulator |
| TW201448437A (en) * | 2013-06-07 | 2014-12-16 | Richtek Technology Corp | Voltage converter controller, voltage converter circuit and control method for voltage converter circuit |
| WO2016095447A1 (en) * | 2014-12-15 | 2016-06-23 | 深圳市中兴微电子技术有限公司 | Frequency locking method and device for buck converter in hysteresis mode |
| CN108880249A (en) * | 2015-08-25 | 2018-11-23 | 华为技术有限公司 | Voltage conversion circuit, method and Multiphase Parallel power-supply system |
| CN105846678A (en) * | 2016-03-25 | 2016-08-10 | 东南大学 | Secondary-ring control system for single-inductor multiple-output switch power converter |
| CN111900878A (en) * | 2020-08-06 | 2020-11-06 | 深圳市凯冠智能科技有限公司 | Adaptive hysteresis control converter for enhancing transient characteristics, control method and equipment |
Non-Patent Citations (1)
| Title |
|---|
| 王海恩;刘志忠;曲高飞;: "开关电源的设计与实现", 自动化与仪器仪表, no. 02, 25 February 2018 (2018-02-25) * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114924608A (en) * | 2022-06-23 | 2022-08-19 | 圣邦微电子(苏州)有限责任公司 | Reference voltage generating circuit |
| CN115242089A (en) * | 2022-07-15 | 2022-10-25 | 圣邦微电子（北京）股份有限公司 | Switch converter and control circuit and control method thereof |
| CN115242089B (en) * | 2022-07-15 | 2024-05-14 | 圣邦微电子（北京）股份有限公司 | Switching converter, control circuit and control method thereof |
| CN116094877A (en) * | 2023-04-11 | 2023-05-09 | 浙江地芯引力科技有限公司 | Differential signal transmission circuit and data transmission device |
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