CN117833681A - Flyback circuit of power adapter and power adapter - Google Patents

Abstract

The application provides a flyback circuit of a power adapter and the power adapter; wherein, flyback circuit includes: the device comprises a first power supply end, a charging unit, a control unit, a second power supply end, a clamping circuit, a discharging unit and a voltage output end; the control unit is electrically connected with the charging unit and is used for controlling the charging unit to be conducted in a first period and disconnected in a second period; the first period precedes the second period; the first end of the charging unit is electrically connected with the first power supply end, the second end of the charging unit is grounded, and the charging unit is used for charging the discharging unit in a first period; the first end of the clamping circuit is electrically connected with the third end of the charging unit, the second end of the clamping circuit is electrically connected with the second power supply end, the clamping circuit is used for supplying leakage inductance energy of the charging unit to the second power supply end in a second period, and the second power supply end is electrically connected with the control unit and used for supplying power to the control unit; and the discharging unit is used for discharging the energy charged by the charging unit in the first period to the voltage output end in the second period.

Description

Flyback circuit of power adapter and power adapter

Technical Field

The present application relates to the field of electronics, and relates to, but is not limited to, flyback circuits for power adapters and power adapters.

Background

In the power adapter, the circuit topology is a flyback circuit, but the traditional flyback circuit needs to consume energy on leakage inductance on one hand, and on the other hand, energy needs to be extracted from the auxiliary winding for power supply of the flyback circuit controller and the driving circuit, so that the energy transmission efficiency is low.

Disclosure of Invention

The flyback circuit of the power adapter and the power adapter can reduce energy loss, so that the energy transmission efficiency of the flyback circuit is improved.

In a first aspect, an embodiment of the present application provides a flyback circuit of a power adapter, where the flyback circuit includes a first power supply terminal, a charging unit, a control unit, a second power supply terminal, a clamping circuit, a discharging unit, and a voltage output terminal; the control unit is electrically connected with the charging unit and is used for controlling the charging unit to be conducted in a first period and disconnected in a second period; the first period of time precedes the second period of time; the first end of the charging unit is electrically connected with the first power supply end, the second end of the charging unit is grounded, and the charging unit is used for charging the discharging unit in the first period; the first end of the clamping circuit is electrically connected with the third end of the charging unit, the second end of the clamping circuit is electrically connected with the second power supply end, the clamping circuit is used for supplying leakage inductance energy of the charging unit to the second power supply end in the second period, and the second power supply end is electrically connected with the control unit and used for supplying power to the control unit; and the discharging unit is used for discharging the energy charged by the charging unit in the first period to the voltage output end in the second period.

In a second aspect, embodiments of the present application provide a power adapter, where the power adapter includes a flyback circuit according to the first aspect.

In the embodiment of the application, a flyback circuit of a power adapter is provided, in which a clamping circuit provides leakage inductance energy of a charging unit to be consumed to a second power supply end so as to supply power to a control unit; therefore, leakage inductance energy of the charging unit is effectively utilized, rather than the leakage inductance energy is completely converted into heat to be consumed, and therefore energy transmission efficiency of the flyback circuit is effectively improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the technical aspects of the application. It is apparent that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.

The flow diagrams depicted in the figures are exemplary only, and do not necessarily include all of the elements and operations/steps, nor must they be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the order of actual execution may be changed according to actual situations.

FIG. 1 is a schematic diagram of a flyback circuit of a power adapter according to the related art;

fig. 2 is a schematic structural diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a flyback circuit of a power adapter according to a second embodiment of the present disclosure;

fig. 4 is a schematic diagram III of a flyback circuit of a power adapter according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 6 is a schematic diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 7 is a schematic diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram seventh of a flyback circuit of the power adapter according to the embodiment of the present application;

fig. 9 is a schematic structural diagram eight of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 10 is a schematic diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 12 is a schematic diagram eleven of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 13 is a schematic diagram showing a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 14 is a schematic structural diagram thirteen of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 15 is a schematic diagram fourteen structural diagrams of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 16 is a schematic diagram fifteen of a flyback circuit of a power adapter according to an embodiment of the present disclosure;

fig. 17 is a schematic structural diagram of a power adapter according to an embodiment of the present application.

Detailed Description

For the purposes, technical solutions and advantages of the embodiments of the present application to be more apparent, the specific technical solutions of the present application will be described in further detail below with reference to the accompanying drawings in the embodiments of the present application. The following examples are illustrative of the present application, but are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of the present application only and is not intended to be limiting of the present application.

In the following description reference is made to "some embodiments," "this embodiment," and examples, etc., which describe a subset of all possible embodiments, but it is to be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with one another without conflict.

The descriptions of the "first, second, third" and the like in the embodiments of the present application are merely used for illustrating and distinguishing the description objects, and are not used for dividing the order, nor do they represent a specific limitation on the number of devices in the embodiments of the present application, and are not intended to constitute any limitation on the embodiments of the present application.

The "electrical connection" in the embodiments of the present application may be a direct connection or an indirect connection, that is, a circuit between two ends of the electrical connection is further connected with other devices.

In an AC-DC (Alternating Current-Direct Current) power adapter with a power of 1-100 w, a common circuit topology is a Flyback (Flyback) circuit, and a modified topology based on the Flyback circuit, such as a quasi-resonant Flyback (Quasi Resonant Flyback, QR Flyback) circuit, an active clamp Flyback (Active Clamping Flyback, ACF) circuit, and the like.

In a related aspect, as shown in the flyback circuit 10 of fig. 1, a first terminal of the capacitor C1 is grounded, and a second terminal is electrically connected to Vin; the clamp circuit includes: c2, R1, R2, and D1, wherein the capacitor C2 is connected in parallel with the resistor R1, connected in series with the resistor R2 and the diode D1, the first end of the capacitor C2 is electrically connected with Vin, the second end is electrically connected with the first end of the resistor R2, the first end of the resistor R1 is electrically connected with Vin, the second end is electrically connected with the first end of the resistor R2, the second end of the resistor R2 is electrically connected with the first end of the diode D1, the second end of the diode D1 is electrically connected with the first pole of the transistor Q1, and the first end of the transistor Q1 is the drain electrode; the second electrode source of the transistor Q1 is electrically connected with the first end of the resistor R3, and the second end of the resistor R3 is grounded; a first end of the primary winding (i.e., the upper left winding) is electrically connected to Vin, and a second end of the primary winding is electrically connected to the first pole drain of transistor Q1; the first end of the auxiliary winding (namely, the winding at the lower left) is electrically connected with the first end of the diode D2, the second end of the auxiliary winding is grounded, the second end of the diode D2 is electrically connected with Aux Vcc, the first end of the capacitor C3 is grounded, and the second end of the capacitor C3 is electrically connected with Aux Vcc; the first end of the secondary winding (namely the right winding) is grounded, the second end of the secondary winding is electrically connected with the first end of the diode D3, the second end of the diode D3 is electrically connected with Vout, the first end of the capacitor Cout is grounded, and the second end of the capacitor Cout is electrically connected with Vout; the principle of the flyback circuit 10 is as follows:

(1) When the transistor Q1 is turned on, the current of the primary winding (i.e., the upper left winding) of the transformer T1 (i.e., the magnetic core) increases, and at the same time, the magnetomotive force on the magnetic core of the transformer also increases with the increase of the current of the primary winding;

(2) When the transistor Q1 is turned off/cut off, the current of the primary winding of the transformer T1 is rapidly reduced to 0, magnetomotive force on a magnetic core of the transformer cannot be suddenly changed, so that currents with corresponding magnitudes are induced in the secondary winding (namely a winding which is changed right) and the auxiliary winding (namely a winding which is changed left), the current magnitude is inversely proportional to the winding turns ratio, and the transmission of energy from the primary winding to the secondary winding and the auxiliary winding is realized;

(3) Because leakage inductance of the transformer exists, energy is transmitted from the primary winding to the secondary winding, not 100% is transmitted, but a small part of energy is transmitted to a primary circuit (namely a circuit consisting of the primary winding, Q1 and R3) through the leakage inductance of the primary winding, so that a large impulse voltage is caused, and the Q1 is in overvoltage risk, and therefore a clamping circuit consisting of C2, R1, R2 and D1 is adopted to consume the energy on the leakage inductance;

(4) Each switching cycle, the auxiliary winding draws a portion of the energy from the core that is used to power the controller of the flyback circuit and the drive circuit of Q1.

Because of the leakage inductance of the transformer, the energy accumulated on the primary winding due to the fact that the primary winding of the transformer cannot be transferred to the secondary winding or the auxiliary winding in each switching cycle needs to be consumed, and a traditional flyback circuit is used for absorbing the energy by a circuit consisting of a resistor R, a capacitor C and a diode D and converting the energy into heat energy. However, the conventional flyback circuit consumes energy on the leakage inductance, and the auxiliary winding is required to extract energy from the magnetic core to maintain the power supply of the flyback controller and the Q1 driving circuit, so that the energy transmission efficiency is low.

Based on the above analysis, the embodiment of the present application provides a flyback circuit of a power adapter, fig. 2 is a schematic structural diagram of the flyback circuit of the power adapter provided in the embodiment of the present application, and as shown in fig. 2, the flyback circuit 20 includes: a first power supply terminal 201, a charging unit 202, a control unit 203, and a second power supply terminal 204, a clamp circuit 205, a discharging unit 206, and a voltage output terminal 207; wherein,

the control unit 203 is electrically connected to the charging unit 202, and is used for controlling the charging unit 202 to be turned on during a first period and turned off during a second period; the first period of time precedes the second period of time;

a first end of the charging unit 202 is electrically connected to the first power supply end 201, a second end of the charging unit 202 is grounded, and the charging unit 202 is configured to charge the discharging unit 206 during the first period;

a first end of the clamping circuit 205 is electrically connected to the third end of the charging unit 202, a second end of the clamping circuit 205 is electrically connected to the second power supply end 204, the clamping circuit 205 is configured to provide leakage inductance energy of the charging unit 202 to the second power supply end 204 during the second period, and the second power supply end 204 is electrically connected to the control unit 203 and is configured to supply power to the control unit 203;

a discharging unit 206 for discharging the energy charged by the charging unit 202 during the first period to the voltage output terminal 207 during the second period.

In the embodiment of the application, a flyback circuit of a power adapter is provided, in which a clamping circuit provides leakage inductance energy of a charging unit to be consumed to a second power supply end so as to supply power to a control unit; therefore, leakage inductance energy of the charging unit is effectively utilized, rather than the leakage inductance energy is completely converted into heat to be consumed, and accordingly energy transmission efficiency of the flyback circuit is effectively improved.

In the embodiment of the present application, the control unit, the charging unit, and the discharging unit are not limited. The control unit, the charging unit and the discharging unit may be integrated chips, integrated circuits or circuits composed of at least one component, for example.

In the embodiment of the present application, the number of components and components that constitute the clamping circuit are not limited, and may absorb leakage inductance energy.

As one possible embodiment, as shown in fig. 3, the clamp 205 includes at least a voltage regulator 2051; a first end of the voltage regulator 2051 is electrically connected to the third end of the charging unit 202, and a second end of the voltage regulator 2051 is electrically connected to the second power supply end 204; voltage regulator 2051 is configured to convert leakage inductance energy of charging unit 202 into a first voltage and provide the first voltage to second power supply terminal 204.

In the embodiment of the present application, the voltage regulator 2051 is not limited, and the voltage regulator 2051 may be an integrated circuit or one or several components. Illustratively, the voltage regulator 2051 may be a linear voltage regulator circuit, a switching voltage regulator circuit, a series voltage regulator circuit, a shunt voltage regulator circuit, or the like; the voltage regulator 2051 may be a normal linear voltage regulator, a regulator tube linear voltage regulator, an integrated linear voltage regulator, a switching load voltage regulator, a switching series voltage regulator, a switching parallel voltage regulator, or the like.

It should be further noted that, in the embodiment of the present application, the first end of the voltage regulator 2051 may be used as a first end of the clamping circuit, and the second end of the voltage regulator 2051 may be directly or indirectly used as a second end of the clamping circuit, that is, the clamping circuit 205 includes the voltage regulator and other components electrically connected to the second end of the voltage regulator, that is, the second end of the voltage regulator 2051 is indirectly grounded through other components.

Illustratively, in some embodiments, as shown in fig. 4, the voltage regulator 2051 includes a voltage regulator diode 2052, a first end of the voltage regulator 2051 being referred to as a cathode of the voltage regulator diode 2052, and a second end of the voltage regulator 2051 being referred to as an anode of the voltage regulator diode 2052.

It should be noted that, in the embodiment of the present application, the second terminal of the zener diode 2052 may be electrically connected to the second power supply terminal 207 directly, or may be indirectly connected, that is, the clamping circuit 205 includes the zener diode 2052 and other components electrically connected to the second terminal of the zener diode 2052, that is, the second terminal of the zener diode 2052 is indirectly grounded through other components.

Illustratively, in some embodiments, as shown in fig. 5, the clamp 205 further includes a first diode 2053 and a first resistor 2054; wherein, the second end of the voltage regulator 2051 is electrically connected to the second power supply end 204, including: the second terminal of the voltage regulator 2051 is electrically connected to an anode of the first diode 2053, a cathode of the first diode 2053 is electrically connected to a first terminal of the first resistor 2054, and a second terminal of the first resistor 2054 is electrically connected to the second power supply terminal 204.

Alternatively, as shown in fig. 6, the clamp 205 further includes a first diode 2053 and a first resistor 2054; wherein, the second end of the voltage regulator 2051 is electrically connected to the second power supply end 204, including: the second terminal of the zener diode 2052 is electrically coupled to the anode of the first diode 2053, the cathode of the first diode 2053 is electrically coupled to the first terminal of the first resistor 2054, and the second terminal of the first resistor 2054 is electrically coupled to the second power supply terminal 204.

In some embodiments, as shown in fig. 7, the charging unit 202 includes at least a first electromagnetic winding 2021 and a transistor 2022; the discharge unit 206 comprises at least a second electromagnetic winding 2061, a magnetic core 2062 and a second diode 2063; wherein,

a first end of the first electromagnetic winding 2021 is electrically connected to the first power supply terminal 201, and a second end of the first electromagnetic winding 2021 is electrically connected to a first pole of the transistor 2022 and a first end of the clamp circuit 205;

the second pole of the transistor 2022 is grounded, and the gate of the transistor 2022 is electrically connected to the control unit 203; the control unit 203 is configured to control the gate voltage of the transistor 202 to turn on the transistor 2022 during the first period or turn off during the second period;

a first electromagnetic winding 2021 for energizing the magnetic core 2062 for the first time period;

a first end of the second electromagnetic winding 2061 is electrically connected to an anode of the second diode 2063, a second end of the second electromagnetic winding 2061 is grounded, and the second electromagnetic winding 2061 is used for transmitting the energy on the magnetic core 2062 to the second diode 2063 in the second period;

the cathode of the second diode 2063 is electrically connected to the voltage output terminal 207, and the second diode 2063 is used for converting the energy transmitted by the magnetic core 2062 into a direct current voltage and transmitting the direct current voltage to the voltage output terminal 207.

Note that in the embodiment of the present application, in the case that the first electrode of the transistor 2022 is the drain, the second electrode of the transistor 2022 is the source; in the case that the first pole of the transistor 2022 is the source, the second pole of the transistor 2022 is the drain; this is related to the type of transistor 2022. Optionally, in some embodiments, the transistor 2022 is a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET).

In the embodiment of the present application, the number of winding turns of the first electromagnetic winding 2021 and the second electromagnetic winding 2061 is not limited, and the winding turn ratio of the first electromagnetic winding 2021 and the second electromagnetic winding 2061 is not limited.

In the present embodiment, the first electromagnetic winding 2021, the magnetic core 2062, and the second electromagnetic winding 2061 constitute a transformer.

It will be appreciated that in the embodiment of the present application, since the principle of the magnetic core transferring energy to the second electromagnetic winding 2061 is electromagnetic induction, the current on the second electromagnetic winding 2061 is alternating current, and the energy on the second electromagnetic winding 2061 is transferred to the voltage output terminal 207 through the second diode 2063, the voltage output terminal 207 can output a direct current voltage by utilizing the unidirectional conductivity of the second diode 2063.

In this embodiment, the second pole of the transistor 2022 may be directly grounded, or may be indirectly grounded, that is, the discharging unit includes the transistor 2022 and other components electrically connected to the second pole of the transistor 2022, that is, the second pole of the transistor 2022 is indirectly grounded through other components.

Illustratively, in some embodiments, as shown in fig. 8, the discharge cell 206 further includes a first capacitance 2064; wherein a first end of the first capacitor 2064 is electrically connected to the voltage output terminal 207, and a second end of the first capacitor 2064 is grounded.

It is understood that in the embodiment of the present application, the discharging unit 206 further includes a first capacitor 2064, and the first capacitor 2064 is electrically connected to the voltage output terminal 207, and the cathode of the second diode 2063 is also electrically connected to the voltage output terminal 207, that is, the first capacitor 2064 is electrically connected to the voltage output terminal 207 and the cathode of the second diode 2063; as such, during the second period, at least a portion of the energy transferred by the second diode 2063 is used to charge the first capacitor 2064, during the first period of the next cycle, the first capacitor 2064 releases the stored energy to the voltage output terminal 207, and during the second period of the next cycle, the first capacitor 2064 may continue to store energy for powering the voltage output terminal 207 during the first period of the next cycle; thus, the voltage output terminal 207 continuously outputs voltage, and the charging efficiency of the power adapter is improved.

In some embodiments, as shown in fig. 9, the charging unit 202 further includes a second resistor 2023; the second pole of transistor 2022 is grounded, including: a second pole of the transistor 2022 is electrically connected to a first end of the second resistor 2023, and a second end of the second resistor 2023 is grounded.

It will be appreciated that in the embodiment of the present application, the second resistor 2023 is electrically connected to the transistor 2022, so that the function of limiting the current in the circuit and the function of dividing the voltage of the transistor 2022 can be utilized by the second resistor 2023, thereby ensuring the normal operation of the transistor 2022.

It should be noted that, in the embodiment of the present application, the foregoing embodiment is optional, that is, the charging unit 202 may include the second resistor 2023, or may not include the second resistor 2023.

In some embodiments, as shown in fig. 10, the flyback circuit 20 further includes a low dropout linear regulator (Low Dropout Regulaor, LDO) 208, wherein: the first end of the LDO 208 is electrically connected to the second power supply end 204, the second end of the LDO 208 is electrically connected to the control unit 203, and the LDO 208 is configured to convert the voltage provided by the second power supply end 204 into an operating voltage of the control unit 203 and provide the operating voltage to the control unit 203.

It is appreciated that in the embodiment of the present application, LDO 208 is electrically connected to flyback circuit 20, and can make the output voltage value a constant voltage value.

It should be noted that, in the embodiment of the present application, the above embodiment is optional, that is, the flyback circuit 20 may include the LDO 208 or may not include the LDO 208.

In some embodiments, as shown in fig. 11, flyback circuit 20 also includes a comparator 209; the first terminal of the LDO 208 is electrically connected to the second power supply terminal 204, including: a first end of the comparator 209 is electrically connected to the second power supply end 204, and a second end of the comparator 209 is electrically connected to a first end of the LDO 208; the comparator 209 is configured to control the LDO 208 to convert the input voltage provided by the second power supply terminal 204 into an operating voltage of the control unit 202 and provide the operating voltage to the control unit 202 when detecting that the input voltage is greater than or equal to the first voltage.

It can be understood that, in the embodiment of the present application, the comparator 209 is connected between the second power supply terminal 204 and the LDO 208, and when the input voltage is detected to be greater than or equal to the first voltage, the comparator 209 outputs a high voltage, and the LDO 208 operates at this time, so as to control the LDO 208 to convert the input voltage into the operating voltage of the control unit 202 and provide the operating voltage to the control unit 202; when the input voltage is detected to be greater than or equal to the first voltage, the comparator 209 does not output the voltage, and the LDO 208 does not operate at this time; thereby reducing the operating time of LDO 208 and further improving the operating efficiency of LDO 208.

In this embodiment of the present application, the specific value of the first voltage is not limited, and the first voltage may be preset or may be modified by a connection resistor.

It should be further noted that, in the embodiment of the present application, the LDO 208 is not limited, and the LDO 208 may be a chip, a step-down circuit, at least one component, or the like

It should be further noted that, in the embodiment of the present application, the flyback circuit 20 may include the comparator 209 or may not include the comparator 209.

As a possible embodiment, as shown in fig. 12, the clamping circuit 205 further includes a second capacitor 2055, where: a first end of the second capacitor 2055 is electrically coupled to the second power supply terminal 204 and a second end of the first resistor 2054; the second terminal of the second capacitor 2055 is grounded.

It can be appreciated that in the embodiment of the present application, when the leakage inductance energy of the charging unit 202 is large, the clamping circuit 205 cannot fully absorb the leakage inductance energy, and the second capacitor 2055 can absorb the leakage inductance energy that the clamping circuit 205 cannot consume, so that the transistor 2022 is not broken down.

Note that in the embodiment of the present application, the clamp circuit 205 may include the second capacitor 2055 or may not include the second capacitor 2055.

In some embodiments, as shown in fig. 13, flyback circuit 20 further includes a load circuit 210, wherein: the first end of the load circuit 210 is grounded to the second end of the discharge unit 206, and the second end of the load circuit 210 is grounded.

In the embodiment of the present application, the load circuit 210 is not limited, and may consume current; the load circuit 210 may be a chip, a circuit that may consume a current, or at least one component, for example.

It will be appreciated that in the embodiment of the present application, the second diode 2063 may generate a spike current during the second period, and the spike current may affect the device to be charged, and the load circuit 210 is used to consume the spike current, so that the output current is more stable, thereby reducing the influence of the power adapter on the device to be charged.

It should be noted that, in the embodiment of the present application, the above embodiment is optional, and the flyback circuit 20 may or may not include the load circuit 210.

In some embodiments, as shown in fig. 14, the flyback circuit 20 further includes a third capacitor 211, wherein: the first end of the third capacitor 211 is electrically connected to the first power supply end 201, and the second end of the third capacitor 211 is grounded.

It is understood that in the embodiment of the present application, the third capacitor 211 is electrically connected to the first power supply terminal 201. The disturbance and ripple of the flyback circuit 20 can be reduced.

It should be noted that, in the embodiment of the present application, the flyback circuit 20 may include the third capacitor 211 or may not include the third capacitor 211.

An embodiment of the present application provides a flyback circuit 20 of a power adapter, and fig. 15 is a schematic diagram fourteen structural diagrams of the flyback circuit of the power adapter provided in the embodiment of the present application, as shown in fig. 15, the flyback circuit 20 includes a first power supply terminal 201, a charging unit 202, a control unit 203, a second power supply terminal 204, a clamping circuit 205, a discharging unit 206, a voltage output terminal 207 and an LDO 208, where,

a first end of the clamping circuit 205 is electrically connected to the third end of the charging unit 202, a second end of the clamping circuit 205 is electrically connected to the second power supply end 204, the clamping circuit 205 is configured to provide leakage inductance energy of the charging unit 202 to the second power supply end 204 during the second period, and the second power supply end 204 is electrically connected to the control unit 203 and is configured to supply power to the control unit 203;

the clamp circuit 205 includes a zener diode 2052, a first diode 2053, and a first resistor 2054; the first end of the zener diode 2052 is electrically connected to the third end of the charging unit 202, the second end of the zener diode 2052 is electrically connected to the anode of the first diode 2053, the cathode of the first diode 2053 is electrically connected to the first end of the first resistor 2054, and the second end of the first resistor 2054 is electrically connected to the second power supply end 204.

A first end of the charging unit 202 is electrically connected to the first power supply end 201, a second end of the charging unit 202 is grounded, and the charging unit 202 is configured to charge the discharging unit 206 during the first period.

A discharging unit 206 for discharging the energy charged by the charging unit 202 during the first period to the voltage output terminal 207 during the second period.

The charging unit 202 includes at least a first electromagnetic winding 2021 and a transistor 2022; the discharge unit 206 comprises at least a second electromagnetic winding 2061, a magnetic core 2062, a second diode 2063 and a first capacitor 2064; wherein,

a first end of the first electromagnetic winding 2021 is electrically connected to the first power supply terminal 201, and a second end of the first electromagnetic winding 2021 is electrically connected to a first pole of the transistor 2022 and a first end of the clamp circuit 205.

The second pole of the transistor 2022 is grounded, and the gate of the transistor 2022 is electrically connected to the control unit 203; the control unit 203 is configured to control the gate voltage of the transistor 202 to turn on the transistor 2022 during the first period or turn off during the second period.

A first electromagnetic winding 2021 for energizing the magnetic core 2062 during the first time period.

The first end of the second electromagnetic winding 2061 is electrically connected to the anode of the second diode 2063, the second end of the second electromagnetic winding 2061 is grounded, and the second electromagnetic winding 2061 is used for transmitting the energy on the magnetic core 2062 to the second diode 2063 during the second period.

The cathode of the second diode 2063 is electrically connected to the voltage output terminal 207, and the second diode 2063 is used for converting the energy transmitted by the magnetic core 2062 into a direct current voltage and then supplying the direct current voltage to the voltage output terminal 207.

A first end of the first capacitor 2064 is electrically connected to the voltage output terminal 207 and a second end of the first capacitor 2064 is grounded.

The flyback circuit 20 further includes an LDO 208, wherein: the first end of the LDO 208 is electrically connected to the second power supply end 204, the second end of the LDO 208 is electrically connected to the control unit 203, and the LDO 208 is configured to convert the voltage provided by the second power supply end 204 into an operating voltage of the control unit 203 and provide the operating voltage to the control unit 203.

Flyback circuit 20 also includes a comparator 209; the first terminal of the LDO 208 is electrically connected to the second power supply terminal 204, including: a first end of the comparator 209 is electrically connected to the second power supply end 204, and a second end of the comparator 209 is electrically connected to a first end of the LDO 208; the comparator 209 is configured to control the LDO 208 to convert the input voltage provided by the second power supply terminal 204 into an operating voltage of the control unit 202 and provide the operating voltage to the control unit 202 when detecting that the input voltage is greater than or equal to the first voltage.

A first end of the load circuit 209 is electrically connected to the cathode of the second diode of the discharge unit 206, and a second end of the load circuit 209 is grounded.

The clamp 205 further includes a second capacitor 2055, wherein: a first end of the second capacitor 2055 is electrically coupled to the second power supply terminal 204 and a second end of the first resistor 2054; the second terminal of the second capacitor 2055 is grounded.

The first end of the third capacitor 211 is electrically connected to the first power supply end 201, and the second end of the third capacitor 211 is grounded.

The charging unit 202 further includes a second resistor 2023; the second pole of transistor 2022 is grounded, including: a second pole of the transistor 2022 is electrically connected to a first end of the second resistor 2023, and a second end of the second resistor 2023 is grounded.

The flyback circuit 20 further includes a third capacitor 211, wherein: the first end of the third capacitor 211 is electrically connected to the first power supply end 201, and the second end of the third capacitor 211 is grounded.

In the embodiment of the present application, a flyback circuit 20 of a power adapter is provided, in the flyback circuit 20, a clamping circuit 205 provides leakage inductance energy of a charging unit 202 to be consumed to a second power supply terminal 204, so as to supply power to a control unit 203; in this way, the leakage inductance energy of the charging unit 202 is effectively utilized, rather than being completely converted into heat to be consumed, thereby effectively improving the energy transmission efficiency of the flyback circuit 20.

An exemplary application of the embodiments of the present application in a practical application scenario will be described below.

The embodiment of the application provides an improved topology based on a novel flyback circuit, which is based on a most basic flyback circuit, and improves an auxiliary power supply part and a clamping circuit part; the flyback circuit provided by the embodiment of the application can use the energy on the leakage inductance to maintain the power supply of the controller of the flyback circuit and the Q1 driving circuit, namely, the leakage inductance energy is provided for the control unit 203, so that a part of energy loss is saved.

In the flyback circuit 20, as shown in fig. 16, a first end of a capacitor C3 (i.e., a third capacitor 211) is grounded, a second end of the capacitor C3 is electrically connected to Vin (i.e., a first power supply end 201), a first end of a primary winding (i.e., a winding on the left side of the magnetic core T2, i.e., a first electromagnetic winding 2021) is electrically connected to Vin, and a second end of the primary winding is electrically connected to a first electrode of a transistor Q2 (i.e., a transistor 2022), wherein the first electrode of the transistor Q2 is a drain electrode; the second end of the primary winding is also electrically connected to the first end of zener diode Z1 (i.e., zener diode 2052); the second end of the zener diode Z1 is electrically connected to the diode D4 (i.e., the first diode 2053), the second end of the diode D4 is electrically connected to the first end of the resistor R5 (i.e., the first resistor 2054), and the second end of the resistor R5 is electrically connected to the Aux Vcc (i.e., the second power supply end 204); the second end of the resistor R5 is also electrically connected to the first end of the capacitor C4 (i.e., the second capacitor 2055), and the second end of the capacitor C4 is grounded; aux Vcc is electrically connected to a first terminal of a low dropout linear regulator (i.e., LDO 208), a second terminal of the low dropout linear regulator is electrically connected to a control unit (i.e., control unit 202), and the control unit is electrically connected to a third gate of transistor Q2; the second pole of the transistor Q2 is electrically connected to the first end of the resistor R4 (i.e., the second resistor 2023), wherein the second pole of the transistor Q2 is a source, and the second end of the resistor R4 is grounded; the first end of the secondary winding (i.e., the winding to the right of the magnetic core T2, i.e., the second electromagnetic winding 2061) is grounded, the second end of the secondary winding is electrically connected to the first end of the diode D5 (i.e., the second diode 2063), the second end of the diode D5 is electrically connected to Vout (i.e., the voltage output segment 207), the first end of the capacitor C4 is grounded, and the second end of the capacitor C4 (i.e., the first capacitor 2064) is electrically connected to Vout.

It can be appreciated that the flyback circuit 20 provided in the embodiments of the present application reduces the auxiliary windings and changes the position of the clamping circuit 205 compared to the conventional flyback circuit 10; specifically, the clamp 205 is placed between the drain of Q2 and PGND, so that leakage inductance energy can be used for auxiliary power supply (controller power supply and driving circuit power supply), i.e., leakage inductance energy is supplied to the control unit 203 instead of directly converting this energy into heat energy for consumption, and energy is extracted from the magnetic core T2 by the auxiliary winding to be supplied to the control unit 203; this reduces the loss caused by "absorbing leakage inductance energy", and at the same time, the auxiliary winding is not required to extract energy from the magnetic core T2 to supply the energy to the control unit 203, thereby reducing the energy loss and improving the energy transmission efficiency.

Compared to the conventional flyback circuit 10, the flyback circuit 20 provided in the embodiment of the present application has a higher Aux Vcc voltage and is used with the LDO 208, that is, the Aux Vcc is connected to the input of the LDO 208, and the output of the LDO 208 is connected to the auxiliary power supply (the controller power supply and the driving circuit power supply), that is, the output is connected to the control unit 203.

It will be appreciated that the present application replaces the original clamp 205 and auxiliary windings with a "modified clamp 205+ldo 208", reduces the auxiliary windings, improves the efficiency of energy transfer from the primary winding to the secondary winding, and simplifies the transformer design, wherein the transformer comprises: first winding 2021, magnetic core T22062, and second winding 2061.

As a possible embodiment, the flyback circuit 20 further comprises a comparator 209; the first terminal of the LDO 208 is electrically connected to the second power supply terminal 204, including: a first end of the comparator 209 is electrically connected to the second power supply end 204, and a second end of the comparator 209 is electrically connected to a first end of the LDO 208; the comparator 209 is configured to control the LDO 208 to convert the input voltage provided by the second power supply terminal 204 into an operating voltage of the control unit 202 and provide the operating voltage to the control unit 202 when detecting that the input voltage is greater than or equal to the first voltage.

It can be understood that, in the embodiment of the present application, the comparator 209 is connected between the second power supply terminal 204 and the LDO 208, and when the input voltage is detected to be greater than or equal to the first voltage, the comparator 209 outputs a high voltage, and the LDO 208 operates at this time, and the LDO 208 converts the input voltage into an operating voltage of the control unit 202 and provides the operating voltage to the control unit 202; when the input voltage is detected to be greater than or equal to the first voltage, the comparator 209 does not output the voltage, and the LDO 208 does not operate at this time; thus, the working time of the LDO 208 can be reduced, and the working efficiency of the LDO 208 can be improved.

As a possible embodiment, the flyback circuit 20 may also be connected to the second terminal of the diode D5 (i.e. the load circuit 210), so as to prevent the excessive leakage inductance energy, which is not absorbed by the Aux Vcc completely, and thus the overvoltage problem of the switching tube

The above description is merely provided for the preferred embodiments of the present application, and the scope of the embodiments of the present application is not limited to the above-mentioned embodiments, but all equivalent modifications or variations according to the disclosure of the embodiments of the present application should be included in the scope of protection described in the claims.

An embodiment of the present application provides a power adapter, and fig. 17 is a schematic structural diagram of the power adapter provided in the embodiment of the present application, as shown in fig. 17, where the power adapter 170 includes a flyback circuit 20.

Based on the above analysis, the embodiments of the present application provide a flyback circuit of a power adapter, where the flyback circuit is used to charge a device to be charged, for example, the device to be charged may include: notebook computers, cell phones, tablet computers, mobile power supplies (such as charger, travel charger), intelligent electronic devices (such as smart watches, smart bracelets, smart glasses, sweeping robots, etc.), small electronic devices (such as wireless headphones, bluetooth speakers, electric toothbrushes, rechargeable wireless mice, etc.), and the like.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" or "some embodiments" or "in one possible implementation" or "example" etc. means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" or "in one possible implementation" or "example" or the like in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in various embodiments of the present application, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present application. The foregoing embodiment numbers of the present application are merely for describing, and do not represent advantages or disadvantages of the embodiments. The foregoing description of various embodiments is intended to highlight differences between the various embodiments, which may be the same or similar to each other by reference, and is not repeated herein for the sake of brevity.

The term "and/or" is herein merely an association relation describing associated objects, meaning that there may be three relations, e.g. object a and/or object B, may represent: there are three cases where object a alone exists, object a and object B together, and object B alone exists.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and device, etc. may be implemented in other manners. The embodiments described above are exemplary only, and further, the various components shown or discussed may be coupled or directly coupled or communicatively coupled to each other via some interface, indirect coupling or communication connection of devices or modules, electrical, mechanical or otherwise.

The features disclosed in the several product embodiments provided in the present application may be combined arbitrarily without conflict to obtain new product embodiments.

The foregoing is merely an embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (10)

1. The flyback circuit of the power adapter is characterized by comprising a first power supply end, a charging unit, a control unit, a second power supply end, a clamping circuit, a discharging unit and a voltage output end;

the control unit is electrically connected with the charging unit and is used for controlling the charging unit to be conducted in a first period and disconnected in a second period; the first period of time precedes the second period of time;

the first end of the charging unit is electrically connected with the first power supply end, the second end of the charging unit is grounded, and the charging unit is used for charging the discharging unit in the first period;

the first end of the clamping circuit is electrically connected with the third end of the charging unit, the second end of the clamping circuit is electrically connected with the second power supply end, the clamping circuit is used for supplying leakage inductance energy of the charging unit to the second power supply end in the second period, and the second power supply end is electrically connected with the control unit and used for supplying power to the control unit;

and the discharging unit is used for discharging the energy charged by the charging unit in the first period to the voltage output end in the second period.

2. The flyback circuit of claim 1 wherein the clamp circuit comprises at least a voltage regulator; the first end of the voltage stabilizer is electrically connected with the third end of the charging unit, and the second end of the voltage stabilizer is electrically connected with the second power supply end;

the voltage stabilizer is used for converting leakage inductance energy of the charging unit into first voltage and providing the first voltage to the second power supply end.

3. The flyback circuit of claim 2 wherein the voltage regulator comprises a zener diode, the first terminal of the voltage regulator being the cathode of the zener diode and the second terminal of the voltage regulator being the anode of the zener diode.

4. A flyback circuit according to claim 2 or 3, wherein the clamp circuit further comprises a first diode and a first resistor; wherein, the second end of voltage regulator with the second power supply end electricity is connected, include:

the second end of the voltage stabilizer is electrically connected with the anode of the first diode, the cathode of the first diode is electrically connected with the first end of the first resistor, and the second end of the first resistor is electrically connected with the second power supply end.

5. Flyback circuit according to any one of claims 1 to 4, characterized in that the charging unit comprises at least a first electromagnetic winding and a transistor; the discharge unit at least comprises a second electromagnetic winding, a magnetic core and a second diode; wherein,

a first end of the first electromagnetic winding is electrically connected with the first power supply end, and a second end of the first electromagnetic winding is electrically connected with the first pole of the transistor and the first end of the clamping circuit;

the second pole of the transistor is grounded, and the grid electrode of the transistor is electrically connected with the control unit; the control unit is used for controlling the gate voltage of the transistor to enable the transistor to be turned on in the first period or turned off in the second period;

the first electromagnetic winding is used for charging the magnetic core in the first period;

a first end of the second electromagnetic winding is electrically connected with an anode of the second diode, a second end of the second electromagnetic winding is grounded, and the second electromagnetic winding is used for transmitting the energy on the magnetic core to the second diode in the second period;

the cathode of the second diode is electrically connected with the voltage output end, and the second diode is used for converting the energy transmitted by the magnetic core into direct-current voltage and transmitting the direct-current voltage to the voltage output end.

6. The flyback circuit of claim 5 wherein the discharge cell further comprises a first capacitor; the first end of the first capacitor is electrically connected with the voltage output end, and the second end of the first capacitor is grounded.

7. The flyback circuit of any of claims 1 to 6, further comprising a low dropout linear regulator LDO, wherein:

the first end of the LDO is electrically connected with the second power supply end, the second end of the LDO is electrically connected with the control unit, and the LDO is used for converting the voltage provided by the second power supply end into the working voltage of the control unit and then providing the working voltage to the control unit.

8. The flyback circuit of claim 7 further comprising a comparator; the first end of the LDO is electrically connected with the second power supply end, and the LDO comprises: the first end of the comparator is electrically connected with the second power supply end, and the second end of the comparator is electrically connected with the first end of the LDO; wherein,

the comparator is used for controlling the LDO to convert the input voltage into the working voltage of the control unit and providing the working voltage to the control unit under the condition that the input voltage provided by the second power supply end is detected to be larger than or equal to the first voltage.

9. The flyback circuit of any of claims 1 to 8, further comprising a load circuit, wherein:

the first end of the load circuit is electrically connected with the second end of the discharge unit, and the second end of the load circuit is grounded.

10. A power adapter comprising the flyback circuit of any one of claims 1 to 9.