CN114362563B - AC/DC control circuit and switching power supply - Google Patents
AC/DC control circuit and switching power supply Download PDFInfo
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- CN114362563B CN114362563B CN202111449939.2A CN202111449939A CN114362563B CN 114362563 B CN114362563 B CN 114362563B CN 202111449939 A CN202111449939 A CN 202111449939A CN 114362563 B CN114362563 B CN 114362563B
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
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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
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
Abstract
The invention discloses an AC/DC control circuit and a switching power supply, wherein the AC/DC control circuit comprises a control chip, a first switching circuit, a second switching circuit and a voltage conversion circuit; the first voltage dividing circuit is connected with the first power supply end and the control chip; the control chip is connected with the first switch circuit, the second switch circuit and the voltage conversion circuit; the first switch circuit is connected with the first power supply end, the second switch circuit and the voltage conversion circuit; the second switch circuit is connected with the voltage conversion circuit; and the voltage conversion circuit is used for outputting a target voltage when the second switch circuit is conducted. The technical scheme can improve the conversion efficiency of the AC/DC control circuit, prevent the overlarge current in the voltage conversion circuit and improve the safety of the AC/DC control circuit.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to an AC/DC control circuit and a switching power supply.
Background
The switching power supply is widely applied to electronic equipment such as mobile phones, televisions, flat panels and the like. As the demand for fast charging of mobile phones increases, the power efficiency of the switching power supply is also increasing.
The conventional AC/DC control circuit in the switching power supply generally adopts a hybrid flyback architecture, so that the AC/DC control circuit works in a ZVS (Zero Voltage Switch, zero voltage switching, ZVS for short) mode, and the conversion efficiency is improved. However, the current of the resonant circuit cannot be directly detected by the conventional hybrid flyback architecture, so that the current in the resonant circuit cannot be effectively controlled, and when the input/output voltage of the AC/DC control circuit changes, the AC/DC control circuit cannot be effectively operated in ZVS mode, and the conversion efficiency of the AC/DC control circuit is affected.
Disclosure of Invention
The embodiment of the invention provides an AC/DC control circuit and a switching power supply, which are used for solving the problem of low conversion efficiency of the AC/DC control circuit.
An AC/DC control circuit comprises a control chip, a first switch circuit, a second switch circuit and a voltage conversion circuit;
the first voltage dividing circuit is connected with the first power supply end and the control chip and is used for outputting an input voltage proportion signal;
the control chip is connected with the first switch circuit, the second switch circuit and the voltage conversion circuit and is used for acquiring a first detection signal from the voltage conversion circuit, outputting a first control signal, acquiring a second detection signal from the voltage conversion circuit and outputting a second control signal according to the input voltage proportion signal;
the first switching circuit is connected with the first power supply end, the second switching circuit and the voltage conversion circuit and is used for outputting switching voltage according to the first control signal;
the second switch circuit is connected with the voltage conversion circuit, is turned on when the switch voltage reaches a certain voltage level, and is turned off when the second control signal is received;
the voltage conversion circuit is used for outputting target voltage according to the switch voltage when the second switch circuit is conducted.
Further, the first switching circuit includes a first switching transistor; the first end of the first switch transistor is connected with the first output end of the control chip, the second end of the first switch transistor is connected with the first power supply end, and the third end of the first switch transistor is connected with the second switch circuit and the voltage conversion circuit.
Further, the second switching circuit includes a second switching transistor; the first end of the second switching transistor is connected with the second output end of the control chip, the second end of the second switching transistor is connected with the output end of the first switching circuit and the first input end of the voltage conversion circuit, and the third end of the second switching transistor is connected with the second input end of the voltage conversion circuit.
Further, the voltage conversion circuit comprises a transformer circuit, a resonance circuit and a voltage detection circuit;
the first input end of the transformer circuit is connected with the third end of the first switch circuit and the second end of the second switch circuit, the second input end of the transformer circuit is connected with the first end of the resonance circuit, and the second end of the resonance circuit is connected with the voltage detection circuit; the voltage detection circuit is connected with the third end of the second switch circuit and the control chip.
Further, the transformer circuit comprises a transformer; the first input end of the transformer is connected with the third end of the first switch circuit and the second end of the second switch circuit, and the second input end of the transformer is connected with the first end of the resonant circuit.
Further, the resonant circuit includes a resonant capacitor; one end of the resonance capacitor is connected with the second input end of the transformer circuit, and the other end of the resonance capacitor is connected with the voltage detection circuit.
Further, the voltage detection circuit comprises a first resistor and a second resistor; the first end of the first resistor is connected with the third end of the second switch circuit, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is grounded; the first end of the first resistor is connected with the connecting node of the third end of the second switch circuit and the first signal detection end of the control chip, and the connecting node of the first resistor and the second resistor is connected with the second signal detection end of the control chip and the second end of the resonance circuit.
Further, the voltage detection circuit comprises a first resistor and a second resistor; the first end of the first resistor is connected with the second end of the resonant circuit, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is grounded; the first end of the first resistor is connected with the connecting node of the second end of the resonant circuit and the first signal detection end of the control chip, and the connecting node of the first resistor and the second resistor is connected with the second signal detection end of the control chip.
Further, the control chip comprises a first signal processing circuit, a second signal processing circuit and a comparator circuit;
the input end of the first signal processing circuit is an input voltage signal detection end and is used for acquiring an input voltage proportion signal, and the output end of the first signal processing circuit is connected with the first input end of the comparator circuit;
the input end of the second signal processing circuit is a reference voltage signal end and is used for acquiring a reference voltage signal, and the output end of the second signal processing circuit is connected with the first input end of the comparator circuit;
the first input end of the comparator circuit is a second signal detection end, the second input end of the comparator circuit is a first signal detection end, and the output end of the comparator circuit is a second output end for outputting the second control signal according to the input voltage proportion signal and the reference voltage signal.
A switching power supply further comprises the AC/DC control circuit.
The AC/DC control circuit and the switching power supply described above, in this embodiment, the AC/DC control circuit includes a first voltage dividing circuit, a control chip, a first switching circuit, a second switching circuit, and a voltage converting circuit; the first voltage dividing circuit is connected with the first power supply end and the control chip; the control chip is connected with the first switch circuit, the second switch circuit and the voltage conversion circuit; the first switch circuit is connected with the first power supply end, the second switch circuit and the voltage conversion circuit; and the second switch circuit is connected with the voltage conversion circuit. In this embodiment, when the first switch circuit is turned on, the first switch circuit outputs a switch voltage, and when the switch voltage reaches a certain voltage level, the second switch circuit is turned on, so that the voltage conversion circuit converts the switch voltage to output a target voltage, and meanwhile, a control chip obtains a second detection signal in the voltage conversion circuit to output a second control signal to control the second switch circuit to turn off, so that the conversion efficiency of the AC/DC control circuit is improved, the current in the voltage conversion circuit is prevented from being excessively large, and the safety of the AC/DC control circuit is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an AC/DC control circuit according to an embodiment of the present invention;
fig. 2 is another circuit schematic of an AC/DC control circuit according to an embodiment of the invention.
In the figure: 10. a first voltage dividing circuit; 20. a control chip; 21. a first signal processing circuit; 22. a second signal processing circuit; 23. a comparator circuit; 30. a first switching circuit; 40. a second switching circuit; 50. a voltage conversion circuit; 51. a transformer circuit; 52. a resonant circuit; 53. and a voltage detection circuit.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the present invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for the same elements throughout for clarity.
It will be understood that when an element or layer is referred to as being "on" …, "" adjacent to "…," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" …, "" directly adjacent to "…," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as "under …," "under …," "below," "under …," "above …," "above," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "under …" and "under …" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for the purpose of providing a thorough understanding of the present invention, detailed structures and steps are presented in order to illustrate the technical solution presented by the present invention. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments in addition to these detailed descriptions.
The present embodiment provides an AC/DC control circuit, as shown in fig. 1, including a first voltage dividing circuit 10, a control chip 20, a first switching circuit 30, a second switching circuit 40, and a voltage converting circuit 50; the first voltage dividing circuit 10 is connected with the first power supply end Vrec and the control chip 20 and is used for outputting an input voltage proportion signal; the control chip 20 is connected with the first switch circuit 30, the second switch circuit 40 and the voltage conversion circuit 50, and is used for acquiring a first detection signal from the voltage conversion circuit 50, outputting a first control signal, acquiring a second detection signal from the voltage conversion circuit 50, and outputting a second control signal according to an input voltage proportion signal; a first switching circuit 30 connected to the first power supply terminal Vrec, the second switching circuit 40, and the voltage converting circuit 50, for outputting a switching voltage according to a first control signal; the second switch circuit 40 is connected with the voltage conversion circuit 50, when the switch voltage reaches a certain voltage level, the second switch circuit 40 is turned on, and when the second control signal is received, the second switch circuit 40 is turned off; the voltage conversion circuit 50 is configured to output a target voltage according to the switching voltage when the second switching circuit 40 is turned on.
The input voltage proportion signal is a signal formed by the first voltage dividing circuit 10 according to the power supply voltage output by the first power supply terminal Vrec. The first detection signal is an electrical signal obtained from the voltage conversion circuit 50. Alternatively, the first detection signal may be a voltage or a current. The first control signal refers to a signal that controls the output of the chip 20. For example, the first control signal may be used to control the on or off of the first switching circuit 30. The first control signal may be a PWM (Pulse width modulation, pulse width modulation, PWM) signal, for example. The second detection signal is an electrical signal obtained from the voltage conversion circuit 50. Alternatively, the second detection signal may be a voltage or a current. The second control signal refers to a signal outputted from the control chip 20. For example, the second control signal may be used to control the on or off of the second switching circuit 40. The switching voltage refers to a voltage output from the first switching circuit 30.
As an example, the first voltage dividing circuit 10 is connected to the first power supply terminal Vrec and the control chip 20. In this example, the first voltage dividing circuit 10 outputs an input voltage proportion signal to the control chip 20 according to the supply voltage provided by the first supply terminal Vrec to feed back the magnitude of the supply voltage output by the first supply terminal Vrec to the control chip 20. Alternatively, the first voltage dividing circuit 10 includes a first voltage dividing resistor and a second voltage dividing resistor connected in series.
As an example, the first output terminal HDRV of the control chip 20 is connected to the first switching circuit 30, the first output terminal LDRV of the control chip 20 is connected to the second switching circuit 40, and the first signal detection terminal cs_neg and the second signal detection terminal CS of the control chip 20 are connected to the voltage converting circuit 50. In this example, the control chip 20 obtains the first detection signal from the voltage conversion circuit 50 to timely output the first control signal according to the first detection signal to control on or off of the first switch circuit 30. The control chip 20 also obtains a second detection signal from the voltage conversion circuit 50, so as to timely control the on or off of the second switch circuit 40 according to the second detection signal.
As another example, the first switching circuit 30 is connected to the first power supply terminal Vrec, the second switching circuit 40, and the voltage converting circuit 50. In this embodiment, after the control chip 20 obtains the first detection signal from the voltage conversion circuit 50, it determines whether to control the on or off state of the first switch circuit 30 according to the first detection signal. Alternatively, the control chip 20 compares the first detection signal with an internal reference voltage, for example, when the magnitude of the first detection signal is greater than the reference voltage, the control chip 20 outputs a first control signal to the first switch circuit 30, and the first switch circuit 30 is turned on when receiving the first control signal output by the control chip 20, and outputs a switch voltage according to a supply voltage provided by the first supply terminal Vrec.
As another example, the second switching circuit 40 is connected to the voltage converting circuit 50, and when the switching voltage reaches a certain voltage level, the second switching circuit 40 is turned on, and when the second control signal is received, the second switching circuit 40 is turned off. In this example, when the switching voltage reaches a certain voltage level, that is, when the switching voltage is enough to turn on the second switching circuit 40, the second switching circuit 40 is turned on, the voltage conversion circuit 50 converts the switching voltage to output the target voltage, and at the same time, the control chip 20 obtains a second detection signal, for example, a current in the voltage conversion circuit 50, from the voltage conversion circuit 50, and when the current in the voltage conversion circuit 50 is too large, the control chip 20 outputs a second control signal to control the second switching circuit 40 to turn off, so as to improve the conversion efficiency of the AC/DC control circuit, and can prevent the current in the voltage conversion circuit 50 from being too large, and improve the safety of the AC/DC control circuit.
In the present embodiment, the AC/DC control circuit includes a first voltage dividing circuit 10, a control chip 20, a first switching circuit 30, a second switching circuit 40, and a voltage converting circuit 50; the first voltage dividing circuit 10 is connected with a first power supply end Vrec and the control chip 20; the control chip 20 is connected with the first switch circuit 30, the second switch circuit 40 and the voltage conversion circuit 50; a first switching circuit 30 connected to the first power supply terminal Vrec, the second switching circuit 40, and the voltage conversion circuit 50; the second switching circuit 40 is connected to the voltage converting circuit 50. In this embodiment, when the first switch circuit 30 is turned on, the first switch circuit 30 outputs a switch voltage, and when the switch voltage reaches a certain voltage level, the second switch circuit 40 is turned on to enable the voltage conversion circuit 50 to convert the switch voltage to output a target voltage, and meanwhile, the control chip 20 obtains a second detection signal in the voltage conversion circuit 50 to output a second control signal to control the second switch circuit 40 to turn off, so as to improve the conversion efficiency of the AC/DC control circuit, prevent the current in the voltage conversion circuit 50 from being excessively large, and improve the safety of the AC/DC control circuit.
In one embodiment, as shown in fig. 1, the first switching circuit 30 includes a first switching transistor M1; the first end of the first switching transistor M1 is connected to the first output terminal HDRV of the control chip 20, the second end of the first switching transistor M1 is connected to the first power supply terminal Vrec, and the third end of the first switching transistor M1 is connected to the second switching circuit 40 and the voltage converting circuit 50.
Preferably, the first switching transistor M1 is a MOS transistor.
As an example, the gate of the first switching transistor M1 is connected to the first output terminal HDRV of the control chip 20, the source of the first switching transistor M1 is connected to the first power supply terminal Vrec, and the drain of the first switching transistor M1 is connected to the second switching circuit 40 and the voltage converting circuit 50. When the gate of the first switching transistor M1 receives the first control signal output by the first output terminal HDRV of the control chip 20, the first switching transistor M1 is turned on, and outputs a switching voltage according to the supply voltage provided by the first supply terminal Vrec.
In the present embodiment, by connecting the first terminal of the first switching transistor M1 to the first output terminal HDRV of the control chip 20, connecting the second terminal of the first switching transistor M1 to the first power supply terminal Vrec, and connecting the third terminal of the first switching transistor M1 to the second switching circuit 40 and the voltage converting circuit 50, it is possible to output the switching voltage according to the first control signal and the power supply voltage supplied from the first power supply terminal Vrec.
In one embodiment, as shown in fig. 1, the second switching circuit 40 includes a second switching transistor M2; the first end of the second switching transistor M2 is connected to the first output terminal LDRV of the control chip 20, the second end of the second switching transistor M2 is connected to the output terminal of the first switching circuit 30 and the first input terminal of the voltage converting circuit 50, and the third end of the second switching transistor M2 is connected to the second input terminal of the voltage converting circuit 50.
Preferably, the second switching transistor M2 is a MOS transistor.
As an example, the gate of the second switching transistor M2 is connected to the first output terminal LDRV of the control chip 20, the source of the second switching transistor M2 is connected to the output terminal of the first switching circuit 30 and the first input terminal of the voltage converting circuit 50, and the drain of the second switching transistor M2 is connected to the second input terminal of the voltage converting circuit 50.
In this embodiment, by connecting the first end of the second switching transistor M2 with the first output end LDRV of the control chip 20, connecting the second end of the second switching transistor M2 with the output end of the first switching circuit 30 and the first input end of the voltage converting circuit 50, and connecting the third end of the second switching transistor M2 with the second input end of the voltage converting circuit 50, the second switching circuit 40 can be turned on when the switching voltage reaches a certain voltage level, so that the voltage converting circuit 50 converts the switching voltage, outputs the target voltage, and the control chip 20 can obtain the second detection signal from the voltage converting circuit 50, and the control chip 20 outputs the second control signal to control the second switching circuit 40 to be turned off, so as to improve the conversion efficiency of the AC/DC control circuit, prevent the current in the voltage converting circuit 50 from being too large, and improve the safety of the AC/DC control circuit.
In one embodiment, as shown in fig. 1, the voltage conversion circuit 50 includes a transformer circuit 51, a resonance circuit 52, and a voltage detection circuit 53; a first input terminal of the transformer circuit 51 is connected to the third terminal of the first switching circuit 30 and the second terminal of the second switching circuit 40, a second input terminal of the transformer circuit 51 is connected to the first terminal of the resonance circuit 52, and the second terminal of the resonance circuit 52 is connected to the voltage detection circuit 53; the voltage detection circuit 53 is connected to the third terminal of the second switching circuit 40 and the control chip 20.
As an example, a first input terminal of the transformer circuit 51 is connected to the third terminal of the first switching circuit 30 and the second terminal of the second switching circuit 40, a second input terminal of the transformer circuit 51 is connected to a first terminal of the resonant circuit 52, and a second terminal of the resonant circuit 52 is connected to the voltage detection circuit 53. In this example, when the first switching circuit 30 is turned on, the switching voltage output from the first switching circuit 30 is stored in the transformer circuit 51 and the resonance circuit 52 in the form of energy, and when the second switching circuit 40 is turned on, the energy stored in the transformer circuit 51 and the resonance circuit 52 is converted into a target voltage, and the target voltage is output from the transformer circuit 51.
As another example, the voltage detection circuit 53 is connected to the third terminal of the second switching circuit 40 and the control chip 20. In the present example, the voltage detection circuit 53 forms a resonant tank with the transformer circuit 51 and the resonance circuit 52 in the above example, so that the first detection signal and the second detection signal can be input to the control chip 20.
In the present embodiment, the voltage conversion circuit 50 includes a transformer circuit 51, a resonance circuit 52, and a voltage detection circuit 53; by connecting the first input terminal of the transformer circuit 51 to the third terminal of the first switching circuit 30 and the second terminal of the second switching circuit 40, connecting the second input terminal of the transformer circuit 51 to the first terminal of the resonant circuit 52, connecting the second terminal of the resonant circuit 52 to the voltage detection circuit 53, and connecting the voltage detection circuit 53 to the third terminal of the second switching circuit 40 and the control chip 20, it is possible to input the first detection signal and the second detection signal to the control chip 20, and at the same time, when the second switching circuit 40 is turned on, the energy stored in the transformer circuit 51 and the resonant circuit 52 is converted into a target voltage, and the target voltage is outputted by the transformer circuit 51.
In one embodiment, as shown in fig. 1, the transformer circuit 51 includes a transformer Lm; a first input terminal of the transformer Lm is connected to the third terminal of the first switching circuit 30 and to the second terminal of the second switching circuit 40, and a second input terminal of the transformer Lm is connected to the first terminal of the resonant circuit 52.
In the present embodiment, the transformer circuit 51 includes a transformer Lm, and by connecting a first input terminal of the transformer Lm to the third terminal of the first switching circuit 30 and the second terminal of the second switching circuit 40 and connecting a second input terminal of the transformer Lm to the first terminal of the resonant circuit 52, it is possible to store the switching voltage in the form of energy, and when the second switching circuit 40 is turned on, the stored energy is converted into a target voltage, and the target voltage is outputted.
In one embodiment, as shown in FIG. 1, the resonant circuit 52 includes a resonant capacitance Cr; one end of the resonance capacitor Cr is connected to the second input terminal of the transformer circuit 51, and the other end of the resonance capacitor Cr is connected to the voltage detection circuit 53.
In the present embodiment, the resonance circuit 52 includes the resonance capacitor Cr, and by connecting one end of the resonance capacitor Cr to the second input terminal of the transformer circuit 51 and connecting the other end of the resonance capacitor Cr to the voltage detection circuit 53, it is possible to store the switching voltage in the form of energy, and when the second switching circuit 40 is turned on, the stored energy is converted into the target voltage by the transformer circuit 51 and the target voltage is outputted.
In one embodiment, as shown in fig. 1, the voltage detection circuit 53 includes a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is connected with the third end of the second switch circuit 40, the second end of the first resistor R1 is connected with the first end of the second resistor R2, and the second end of the second resistor R2 is grounded; the connection node of the first end of the first resistor R1 and the third end of the second switch circuit 40 is connected to the first signal detection end cs_neg of the control chip 20, and the connection node of the first resistor R1 and the second resistor R2 is connected to the second signal detection end CS of the control chip 20 and the second end of the resonance circuit 52.
In this embodiment, a first end of the first resistor R1 is connected to the third end of the second switch circuit 40, a second end of the first resistor R1 is connected to a first end of the second resistor R2, and a second end of the second resistor R2 is grounded; the connection node of the first end of the first resistor R1 and the third end of the second switch circuit 40 is connected to the first signal detection end cs_neg of the control chip 20, and the connection node of the first resistor R1 and the second resistor R2 is connected to the second signal detection end CS of the control chip 20 and the second end of the resonance circuit 52. In this example, when the first switching circuit 30 is turned on, the switching voltage is stored in the form of energy in the resonant circuit formed by the transformer circuit 51 and the resonant circuit 52, and the control chip 20 obtains the second detection signal on the connection node of the first resistor R1 and the second resistor R2 through the second signal detection terminal CS to determine whether the first control signal needs to be output to turn off the first switching circuit 30, and at this time, the second switching circuit 40 is still in the off state. Since the switching voltage is pulled down to a negative voltage, which is determined by the body diode drop of the second switching transistor M2 in the second switching circuit 40 and the voltage drop across the first resistor R1, for example, the negative voltage is typically-0.5V to-2V. When the control chip 20 determines that the first switching circuit 30 needs to be turned off, a first control signal is output, and when the turn-off time of the first switching circuit 30 exceeds the dead time or the switching voltage reaches a certain voltage level, the second switching circuit 40 is turned on, and the energy stored in the transformer circuit 51 and the resonance circuit 52 is released to the secondary side, thereby outputting the target voltage. Meanwhile, the control chip 20 can determine the magnitude of the negative current on the resonant tank through the first detection signal acquired by the first signal detection terminal cs_neg, so as to accurately control the negative current. For example, when the voltage across the first resistor R1 is sufficiently high, that is, when the amplitude of the first detection signal is too large, the control chip 20 outputs the second control signal to turn off the second switching circuit 40, so that the control chip 20 can accurately control the negative current in the resonant tank by detecting the first detection signal across the first resistor R1 and outputting the second control signal, thereby improving the conversion efficiency of the AC/DC control circuit, preventing the current in the voltage conversion circuit 50 from being too large, and improving the safety of the AC/DC control circuit.
In one embodiment, as shown in fig. 2, the voltage detection circuit 53 includes a first resistor R1 and a second resistor R2; a first end of the first resistor R1 is connected to a second end of the resonant circuit 52, a second end of the first resistor R1 is connected to a first end of the second resistor R2, and a second end of the second resistor R2 is grounded; the connection node of the first end of the first resistor R1 and the second end of the resonant circuit 52 is connected to the first signal detection terminal cs_neg of the control chip 20, and the connection node of the first resistor R1 and the second resistor R2 is connected to the second signal detection terminal CS of the control chip 20.
In the present embodiment, the voltage detection circuit 53 includes a first resistor R1 and a second resistor R2; a first end of the first resistor R1 is connected to a second end of the resonant circuit 52, a second end of the first resistor R1 is connected to a first end of the second resistor R2, and a second end of the second resistor R2 is grounded; the connection node of the first end of the first resistor R1 and the second end of the resonant circuit 52 is connected to the first signal detection terminal cs_neg of the control chip 20, and the connection node of the first resistor R1 and the second resistor R2 is connected to the second signal detection terminal CS of the control chip 20. In this example, when the first switching circuit 30 is turned on, the switching voltage is stored in the form of energy in the resonant circuit formed by the transformer circuit 51 and the resonant circuit 52, and the control chip 20 obtains the second detection signal on the connection node of the first resistor R1 and the second resistor R2 through the second signal detection terminal CS to determine whether the first control signal needs to be output to turn off the first switching circuit 30, and at this time, the second switching circuit 40 is still in the off state. Since the switching voltage is pulled down to a negative voltage, which is determined by the body diode drop of the second switching transistor M2 in the second switching circuit 40 and the voltage drop across the first resistor R1, for example, the negative voltage is typically-0.5V to-2V. When the control chip 20 determines that the first switching circuit 30 needs to be turned off, a first control signal is output, and when the turn-off time of the first switching circuit 30 exceeds the dead time or the switching voltage reaches a certain voltage level, the second switching circuit 40 is turned on, and the energy stored in the transformer circuit 51 and the resonance circuit 52 is released to the secondary side, thereby outputting the target voltage. Meanwhile, the control chip 20 can determine the magnitude of the negative current on the resonant tank through the first detection signal acquired by the first signal detection terminal cs_neg, so as to accurately control the negative current. For example, when the voltage across the first resistor R1 is sufficiently high, that is, when the amplitude of the first detection signal is too large, the control chip 20 outputs the second control signal to turn off the second switching circuit 40, so that the control chip 20 can accurately control the negative current in the resonant tank by detecting the first detection signal across the first resistor R1 and outputting the second control signal, thereby improving the conversion efficiency of the AC/DC control circuit, preventing the current in the voltage conversion circuit 50 from being too large, and improving the safety of the AC/DC control circuit. .
In an embodiment, the control chip 20 includes a first signal processing circuit 21, a second signal processing circuit 22, and a comparator circuit 23; the input end of the first signal processing circuit 21 is an input voltage signal detection end vin_sens, and is used for obtaining an input voltage proportion signal, and the output end of the first signal processing circuit 21 is connected with the first input end of the comparator circuit 23; the input end of the second signal processing circuit 22 is a reference voltage signal end Vref and is used for acquiring a reference voltage signal, and the output end of the second signal processing circuit 22 is connected with the first input end of the comparator circuit 23; a first end of the first comparator circuit 23 is connected to the second signal detection end CS; the second input terminal of the comparator circuit 23 is a first signal detection terminal cs_neg, and the output terminal of the comparator circuit 23 is a first output terminal LDRV for outputting a second control signal according to the input voltage ratio signal and the reference voltage signal.
As an example, the first signal processing circuit 21 includes a first amplifier, a third voltage dividing resistor, a fourth voltage dividing resistor, a first transistor, and a first current mirror circuit; the first input end of the first amplifier is an input voltage signal detection end VIN_sens, the second input end of the first amplifier is connected with the first end of the third voltage dividing resistor and the first end of the fourth voltage dividing resistor, the output end of the first amplifier is connected with the first end of the first transistor, the second end of the third voltage dividing resistor is connected with the third end of the first transistor, the second end of the fourth voltage dividing resistor is grounded, the second end of the first transistor is connected with the first end of the first current mirror circuit, and the second end of the first current mirror circuit is connected with the first input end of the comparator circuit 23 and used for acquiring an input voltage proportion signal, processing the input voltage proportion signal and outputting a first processing signal. Preferably, the first transistor is a MOS transistor, the first end of the first transistor is a gate, the second end of the first transistor is a source, and the third end of the first transistor is a drain.
As another example, the second signal processing circuit 22 includes a second amplifier, a fifth voltage dividing resistor, a sixth voltage dividing resistor, a second transistor, and a second current mirror circuit; the first input end of the second amplifier is a reference voltage signal end Vref, the second input end of the second amplifier is connected with the first end of the fifth voltage dividing resistor and the first end of the sixth voltage dividing resistor, the output end of the second amplifier is connected with the first end of the second transistor, the second end of the fifth voltage dividing resistor is connected with the third end of the second transistor, the second end of the sixth voltage dividing resistor is grounded, the second end of the second transistor is connected with the first end of the second current mirror circuit, and the second end of the second current mirror circuit is connected with the first input end of the comparator circuit 23 for acquiring a reference voltage signal, processing the reference voltage signal and outputting a second processing signal. Preferably, the second transistor is a MOS transistor, the second end of the second transistor is a gate, the second end of the second transistor is a source, and the third end of the second transistor is a drain.
As another example, the comparator circuit 23 includes a third resistor and a signal comparator; the first input end of the signal comparator is connected with the first end of the third resistor, the output end of the first signal processing circuit 21 and the output end of the second signal processing circuit 22, the second end of the third resistor is connected with the second signal detection end CS of the control chip 20, the second input end of the signal comparator is the first signal detection end CS_NEG, the output end of the signal comparator is connected with the first output end LDRV of the control chip 20, and the second control signal is output according to the first processing signal and the second processing signal.
It should be noted that, the first current mirror circuit and the second current mirror circuit in the present embodiment may use the existing current mirror technology, which is not described herein again.
In the present embodiment, the control chip 20 includes a first signal processing circuit 21, a second signal processing circuit 22, and a comparator circuit 23, obtains an input voltage proportion signal through the first signal processing circuit 21, obtains a reference voltage signal terminal Vref through the second signal processing circuit 22, and outputs a second control signal through the comparator circuit 23 according to the input voltage proportion signal and the reference voltage signal, thereby realizing control of the second switch circuit 40.
The embodiment provides a switching power supply, which further comprises the AC/DC control circuit.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (5)
1. An AC/DC control circuit is characterized by comprising a first voltage dividing circuit, a control chip, a first switch circuit, a second switch circuit and a voltage conversion circuit;
the first voltage dividing circuit is connected with the first power supply end and the control chip and is used for outputting an input voltage proportion signal;
the control chip is connected with the first switch circuit, the second switch circuit and the voltage conversion circuit and is used for acquiring a second detection signal from the voltage conversion circuit, outputting a first control signal according to the input voltage proportion signal and used for controlling the first switch circuit, acquiring a first detection signal from the voltage conversion circuit and outputting a second control signal and used for controlling the second switch circuit;
the first switching circuit is connected with the first power supply end, the second switching circuit and the voltage conversion circuit and is used for outputting switching voltage according to the first control signal;
the second switching circuit is connected with the voltage conversion circuit, and is conducted when the switching voltage reaches a preset voltage level; controlling the second switch circuit to be turned off based on the first detection signal;
the voltage conversion circuit is used for outputting target voltage according to the switch voltage when the second switch circuit is turned on;
the second switching circuit includes a second switching transistor; the first end of the second switching transistor is connected with the second output end of the control chip, the second end of the second switching transistor is connected with the output end of the first switching circuit and the first input end of the voltage conversion circuit, and the third end of the second switching transistor is connected with the second input end of the voltage conversion circuit;
the voltage conversion circuit comprises a transformer circuit, a resonant circuit and a voltage detection circuit; the first input end of the transformer circuit is connected with the first switch circuit and the second end of the second switch transistor, the second input end of the transformer circuit is connected with the first end of the resonance circuit, and the second end of the resonance circuit is connected with the voltage detection circuit; the voltage detection circuit is connected with the third end of the second switching transistor and the control chip;
the voltage detection circuit comprises a first resistor and a second resistor; the first end of the first resistor is connected with the third end of the second switch transistor, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is grounded; the connection node of the first end of the first resistor and the third end of the second switch transistor is connected with the first signal detection end of the control chip, and the connection node of the first resistor and the second resistor is connected with the second signal detection end of the control chip and the second end of the resonance circuit;
alternatively, the voltage detection circuit includes a first resistor and a second resistor; the first end of the first resistor is connected with the second end of the resonant circuit, the second end of the first resistor is connected with the first end of the second resistor, and the second end of the second resistor is grounded; the first end of the first resistor is connected with the connecting node of the second end of the resonant circuit and the first signal detection end of the control chip, and the connecting node of the first resistor and the second resistor is connected with the second signal detection end of the control chip.
2. The AC/DC control circuit of claim 1, wherein the first switching circuit comprises a first switching transistor; the first end of the first switch transistor is connected with the first output end of the control chip, the second end of the first switch transistor is connected with the first power supply end, and the third end of the first switch transistor is connected with the second switch circuit and the voltage conversion circuit.
3. The AC/DC control circuit of claim 1, wherein the transformer circuit comprises a transformer; the first input end of the transformer is connected with the first switch circuit and the second end of the second switch transistor, and the second input end of the transformer is connected with the first end of the resonant circuit.
4. The AC/DC control circuit of claim 3, wherein said resonant circuit comprises a resonant capacitor; one end of the resonance capacitor is connected with the second input end of the transformer, and the other end of the resonance capacitor is connected with the voltage detection circuit.
5. A switching power supply, further comprising an AC/DC control circuit as claimed in any one of claims 1 to 4.
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| CN101106846A (en) * | 2006-09-13 | 2008-01-16 | 阮世良 | A driving power and control method for magnetic control tube |
| CN101151789A (en) * | 2005-04-01 | 2008-03-26 | Nxp股份有限公司 | Control of a resonant converter |
| CN111682773A (en) * | 2020-05-14 | 2020-09-18 | 杭州电子科技大学 | Primary side constant current controlled resonance conversion device and implementation method |
| CN113394985A (en) * | 2021-07-21 | 2021-09-14 | 矽力杰半导体技术(杭州)有限公司 | Control circuit, resonant converter and integrated circuit control chip |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI508424B (en) * | 2013-10-11 | 2015-11-11 | Delta Electronics Inc | Solar photovoltaic power conversion system and method of operating the same |
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| CN101151789A (en) * | 2005-04-01 | 2008-03-26 | Nxp股份有限公司 | Control of a resonant converter |
| CN101106846A (en) * | 2006-09-13 | 2008-01-16 | 阮世良 | A driving power and control method for magnetic control tube |
| CN111682773A (en) * | 2020-05-14 | 2020-09-18 | 杭州电子科技大学 | Primary side constant current controlled resonance conversion device and implementation method |
| CN113394985A (en) * | 2021-07-21 | 2021-09-14 | 矽力杰半导体技术(杭州)有限公司 | Control circuit, resonant converter and integrated circuit control chip |
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