CN109905042B

CN109905042B - Power supply equipment and power supply circuit thereof

Info

Publication number: CN109905042B
Application number: CN201910212189.3A
Authority: CN
Inventors: 杨小华
Original assignee: Shenzhen ICM Microelectronics Co Ltd
Current assignee: Shenzhen Chuangxin Microelectronics Co ltd
Priority date: 2019-03-20
Filing date: 2019-03-20
Publication date: 2020-04-14
Anticipated expiration: 2039-03-20
Also published as: CN109905042A

Abstract

The power supply circuit converts the accessed high-voltage alternating current into high-voltage direct current through a high-voltage input module, a primary power control module samples the coupled output voltage of an auxiliary coil end of a transformer, the transformer is controlled to generate charging energy according to the high-voltage direct current according to the sampling result, a secondary rectification control module generates charging voltage according to the charging energy, and the charging voltage is rectified and then charged to a load; the secondary rectification control module is also used for detecting the output voltage in the charging process, and feeding the detection result back to the primary power control module through the transformer, and the primary power control module adjusts the input power of the transformer according to the detection result, so that the power circuit is simple in circuit structure while effectively charging the load, the size, the number of components and electronic garbage generated by the power circuit are reduced, and the cost is low.

Description

Power supply equipment and power supply circuit thereof

Technical Field

The present disclosure relates to the field of power supply technologies, and in particular, to a power supply device and a power supply circuit thereof.

Background

In recent years, as the performance of portable terminals such as mobile phones and tablet computers has been improved and rapidly popularized, power supply devices matched with the portable terminals have also been increased explosively, for example, power supplies for portable terminals such as 5V1A and 5V 2A.

However, as the charging power increases, the power supply circuit scheme of the power supply device becomes more complex, and as the power supply circuit scheme becomes more complex, the size of the power supply circuit increases, the number of components increases, the cost increases, and more electronic waste is generated.

In conclusion, the conventional power supply circuit has the problems of large volume, large number of components, high cost and more generated electronic wastes.

Disclosure of Invention

The utility model aims to provide a power supply unit and power supply circuit thereof to solve current power supply circuit and have bulky, the components and parts is in large quantity, with high costs and the many problems of electron rubbish.

The present disclosure is achieved in this way, and a first aspect of the present disclosure provides a power supply circuit including:

the device comprises a high-voltage input module, a primary power control module, a transformer and a secondary rectification control module;

the high-voltage input module is connected with a primary coil of a transformer, the primary power control module is connected with the primary coil and an auxiliary coil of the transformer, a secondary coil of the transformer is connected with the secondary rectification control module, and the secondary rectification control module is connected with a load;

the high-voltage input module converts the accessed high-voltage alternating current into high-voltage direct current, the primary power control module samples the coupling output voltage of the auxiliary coil end of the transformer, the transformer is controlled to generate charging energy according to the high-voltage direct current according to the sampling result, and the secondary rectification control module generates charging voltage according to the charging energy, rectifies the charging voltage and then charges the load; the secondary rectification control module is also used for detecting the output voltage in the charging process and feeding back the detection result to the primary power control module through the transformer, and the primary power control module adjusts the input power of the transformer according to the detection result.

A second aspect of the present disclosure provides a power supply apparatus including the power supply circuit of the first aspect.

The power supply circuit adopts a high-voltage input module, a primary power control module, a transformer and a secondary rectification control module, so that the high-voltage input module converts the accessed high-voltage alternating current into high-voltage direct current, the primary power control module samples the coupling output voltage of an auxiliary coil end of the transformer, the transformer is controlled to generate charging energy according to the high-voltage direct current according to the sampling result, and the secondary rectification control module generates charging voltage according to the charging energy and charges a load after rectifying the charging voltage; the secondary rectification control module is also used for detecting the output voltage in the charging process, and feeding the detection result back to the primary power control module through the transformer, and the primary power control module adjusts the input power of the transformer according to the detection result, so that the power circuit is simple in circuit structure while effectively charging the load, the size, the number of components and electronic garbage generated by the power circuit are reduced, and the cost is low.

Drawings

To more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed for the embodiments or the prior art descriptions will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and those skilled in the art can also obtain other drawings according to the drawings without inventive labor.

Fig. 1 is a schematic structural diagram of a power supply circuit according to an embodiment of the present disclosure;

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

fig. 3 is a schematic diagram of a partial circuit structure of a primary power control chip in a power supply circuit according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram of a partial circuit structure of a primary power control chip in a power supply circuit according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram of a partial circuit structure of a primary power control chip in a power supply circuit according to an embodiment of the present disclosure;

fig. 6 is a schematic circuit structure diagram of a secondary rectification control chip in a power supply circuit according to an embodiment of the present disclosure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the disclosure and are not intended to limit the disclosure.

Furthermore, in the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent to one skilled in the art that the present disclosure may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present disclosure with unnecessary detail.

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are some, but not all embodiments of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

In order to explain the technical solution of the present disclosure, the following description is given by way of specific examples.

The embodiment of the present disclosure provides a power supply circuit 1, as shown in fig. 1, the power supply circuit 1 includes a high voltage input module 10, a primary power control module 11, a transformer 12, and a secondary rectification control module 13.

The high voltage input module 10 is connected to a primary coil of a transformer 12, the primary power control module 11 is connected to the primary coil and an auxiliary coil of the transformer 12, a secondary coil of the transformer 12 is connected to a secondary rectification control module 13, and the secondary rectification control module 13 is connected to a load (not shown).

Specifically, the high-voltage input module 10 converts the accessed high-voltage alternating current into high-voltage direct current, the primary power control module 11 samples the coupling output voltage of the auxiliary coil end of the transformer 12, controls the transformer 12 to generate charging energy according to the high-voltage direct current according to the sampling result, and the secondary rectification control module 13 generates charging voltage according to the charging energy, rectifies the charging voltage and charges the load; the secondary rectification control module 13 is further configured to detect an output voltage during the charging process, and feed back a detection result to the primary power control module 11 through the transformer 12, where the primary power control module 11 adjusts the input power of the transformer 12 according to the detection result.

In this embodiment, the power circuit high-voltage input module provided by the embodiment of the present disclosure converts the accessed high-voltage ac into high-voltage dc, the primary power control module samples the coupling output voltage of the auxiliary winding end of the transformer, controls the transformer to generate charging energy according to the high-voltage dc according to the sampling result, and the secondary rectification control module generates charging voltage according to the charging energy, rectifies the charging voltage, and charges the charging voltage to the load; the secondary rectification control module is also used for detecting the output voltage in the charging process, the detection result is fed back to the primary power control module through the transformer, the primary power control module adjusts the input power of the transformer according to the detection result, the circuit structure is simple while the power circuit can effectively charge the load, the size of the power circuit is reduced, the number of components and electronic garbage is reduced, the cost is low, and the problems that the existing power circuit is large in size, large in number of components and electronic garbage, high in cost and large in electronic garbage are solved.

Further, as an embodiment of the present disclosure, as shown in fig. 2, the power circuit further includes a filtering module 14.

The filter module 14 is connected to the high voltage input module 10 and the primary winding of the transformer 12. Specifically, the filtering module 14 is configured to filter interference of the high-voltage direct current converted and output by the high-voltage input module 10.

In the embodiment of the present disclosure, the filter module 14 is disposed in the circuit 1, so that the filter module 14 performs interference filtering on the high-voltage direct current converted by the high-voltage input module 10 according to the alternating current, thereby preventing the high-voltage direct current with impurities from affecting the back-end circuit, and ensuring the reliability of the circuit.

Further, in the implementation, as shown in fig. 2, the filtering module 14 is implemented by using an inductor L1, a capacitor C1, and a capacitor C2.

Specifically, a first terminal of the inductor L1 is connected to the first terminal of the capacitor C1 and to the high voltage input module 10, a second terminal of the inductor L1 is connected to the first terminal of the capacitor C2 and the primary winding of the transformer 12, and a second terminal of the capacitor C1 and a second terminal of the capacitor C2 are connected to the equipotential terminal and to the high voltage input module 10.

Further, as an embodiment of the present disclosure, as shown in fig. 2, the high voltage input module 10 is implemented by using a full wave rectifier circuit and a current limiting resistor. The full-wave rectifying circuit comprises rectifying diodes D1, D2, D3 and D4, and the current-limiting resistor is realized by a resistor R1.

Specifically, the anode of the rectifier diode D1 is connected to the cathode of the rectifier diode D4 and to the anode of the external ac power supply device, the cathode of the rectifier diode D1 is connected to the cathode of the rectifier diode D2 and to the first end of the inductor L1, the anode of the rectifier diode D2 is connected to the cathode of the rectifier diode D3 and to the first end of the current-limiting resistor R1, the second end of the current-limiting resistor R1 is connected to the cathode of the external ac power supply device, the anode of the rectifier diode D3 is connected to the anode of the rectifier diode D4 and to the second end of the capacitor C1 and to the second end of the capacitor C2.

Further, as an embodiment of the present disclosure, as shown in fig. 2, the primary power control module 11 includes a primary power control chip U1 and an energy storage filter capacitor C3.

The primary power control chip U1 is connected to the primary winding, the auxiliary winding and the energy storage filter capacitor C3 of the transformer 12, and the energy storage filter capacitor C3 is connected to the auxiliary winding of the transformer 12.

Specifically, the primary power control chip U1 generates a supply voltage according to the voltage at the primary coil end of the transformer 12, and the energy storage filter capacitor C3 stores energy according to the supply voltage to provide a working voltage to the primary power control chip U1;

the primary power control chip U1 is further configured to sample a coupling output voltage at the auxiliary winding end of the transformer 12, control the transformer 12 to generate charging energy according to the high-voltage direct current according to a sampling result, and adjust the input power of the transformer 12 according to a detection result fed back by the secondary rectification control module 13.

Further, as shown in fig. 2, the fifth pin 5, the sixth pin 6, the seventh pin 7, and the eighth pin 8 of the primary power control chip U1 are connected in common and connected to the primary coil of the transformer 12, the first pin 1 of the primary power control chip U1 is connected to the auxiliary coil of the transformer 12, the second pin 2 of the primary power control chip U1 is connected to the energy storage filter capacitor C3, the fourth pin 4 of the primary power control chip U1 and the energy storage filter capacitor C3 are connected in common to an equipotential end, and the energy storage filter capacitor C3 is connected to the auxiliary coil of the transformer 12.

Further, as an embodiment of the present disclosure, as shown in fig. 3, the primary power control chip U1 includes a voltage sampling module 111, an error amplifying module 112, a constant voltage and constant current control module 113, a logic control module 114, a first driving module 115, a current sampling module 116, an overcurrent protection module 117, a power starting module 118, a power switching module 119, and a switch tube 120.

The voltage sampling module 111 is connected to an auxiliary winding of the transformer 12 (not shown in the figures, please refer to fig. 2) and the error amplifying module 112, the error amplifying module 112 is connected to the constant voltage and constant current control module 113, the constant voltage and constant current control module 113 is connected to the logic control module 114, the logic control module 114 is connected to the overcurrent protection module 117, the power switch module 119 and the first driving module 115, the first driving module 115 is connected to the switching tube 120, the switching tube 120 is connected to the power switch module 119 and a primary winding of the transformer 12, the power switch module 119 is connected to the power starting module 118 and the energy storage filter capacitor C3 (not shown in the figures, please refer to fig. 2), and the current sampling module 116 is connected to the power switch module 119 and the overcurrent protection module 117.

Specifically, after the power circuit 1 is powered on, the switching tube 120 is turned on according to the voltage at the primary coil end of the transformer 12, and when the primary power control chip U1 works, the logic control module 114 and the power start module 118 control the power switch module 119 to be in the first on state, so that the power switch module 119 outputs the power supply voltage; then, the power supply starting module 118 detects the power supply voltage, and when the power supply voltage is lower than a first preset power supply voltage, the and logic control module 114 controls the power supply switch module 119 to be continuously in a first conduction state, and when the power supply voltage is higher than a second preset power supply voltage, the and logic control module 114 controls the power supply switch module 119 to be continuously in a second conduction state;

further, when the switching tube 120 is turned on and the power switch module 119 is in the second on state, the current sampling module 116 samples the current at the primary coil end of the transformer 12 and feeds a current sampling result back to the overcurrent protection module 117, the overcurrent protection module 117 generates an overcurrent protection signal according to the current sampling result and the overcurrent reference voltage, and the logic control module 114 generates an overcurrent protection control signal according to the overcurrent protection signal and sends the overcurrent protection control signal to the first driving module 115;

the voltage sampling module 111 samples the coupled output voltage of the auxiliary coil end of the transformer 12 to obtain a sampling voltage, the error amplification module 112 compares the sampling voltage with a reference voltage to generate an error amplification signal, the constant voltage and constant current control module 113 generates a control signal according to the error amplification signal, the logic control module 114 generates a first switch control signal according to the control signal and the overcurrent protection control signal, and the first driving module 115 controls the on-off frequency of the switching tube 120 according to the first switch control signal;

the voltage sampling module 111 is further configured to generate a load response signal according to the detection result, the error amplification module 112 generates a load response amplification signal according to the load response signal, the constant voltage and constant current control module 113 generates a load response control signal according to the load response amplification signal, the logic control module 114 generates a second switch control signal according to the load response control signal, and the first driving module 115 controls the on-off frequency of the switching tube 120 according to the second switch control signal.

Further, as an embodiment, the primary power control chip U1 further includes an output line compensation module 121, an input voltage compensation module 122, an overvoltage protection module 123, and a short-circuit protection module 124.

The output line compensation module 121 is connected to the error amplification module 112 and the voltage sampling module 111, the input voltage compensation module 122 is connected to the voltage sampling module 111 and the overcurrent protection module 117, the overvoltage protection module 123 is connected to the voltage sampling module 111 and the logic control module 114, and the short-circuit protection module 124 is also connected to the voltage sampling module 111 and the logic control module 114.

Specifically, the input voltage compensation module 122 is configured to compensate for a main-side current deviation caused by high-voltage and low-voltage inputs; the output line compensation module 121 is used for compensating voltage drops of the output cables under different loads; the overvoltage protection module 123 generates an overvoltage protection signal by comparing the sampling voltage with an internal overvoltage protection reference and outputs the overvoltage protection signal to the logic control module 114, so as to realize output overvoltage protection; the short-circuit protection module 124 generates a short-circuit protection signal by comparing the sampled voltage with an internal short-circuit protection reference and outputs the short-circuit protection signal to the logic control module 114 to implement output short-circuit protection.

It should be noted that, in the embodiment of the present disclosure, the circuit structures and the operating principles of the output line compensation module 121, the input voltage compensation module 122, the overvoltage protection module 123, and the short-circuit protection module 124 are the same as those of the output line compensation module, the input voltage compensation module, the overvoltage protection module, and the short-circuit protection module in the existing power circuit, and specific reference may be made to the prior art, which is not described herein again.

Further, in practical implementation, as shown in fig. 4, the voltage sampling module 111 includes: a first comparing unit 111a, a second comparing unit 111b, a logic processing unit 111c, and a sampling unit 111 d.

The first comparing unit 111a is connected to an auxiliary winding of the transformer 12 (not shown in the figure, please refer to fig. 2) and the logic processing unit 111c, the second comparing unit 111b is connected to the auxiliary winding of the transformer 12, the logic processing unit 111c and the sampling unit 111d, the logic processing unit 111c is connected to the sampling unit 111d and the error amplifying module 112 (not shown in the figure, please refer to fig. 3), and the sampling unit 111d is connected to the auxiliary winding of the transformer 12 and the error amplifying module 112.

Specifically, the first comparing unit 111a generates a first sampling comparison signal according to the coupling output voltage, the logic processing unit 111c generates a first sampling control signal according to the first sampling comparison signal, and the sampling unit 111d samples the coupling output voltage according to the first sampling control signal to output a sampling voltage; the second comparing unit 111b generates a second sampling comparison signal according to the coupling output voltage and the sampling voltage, the logic processing unit 111c generates a second sampling control signal according to the second sampling comparison signal, and the sampling unit 111d stops sampling the coupling output voltage according to the second sampling control signal;

in addition, the first comparing unit 111a is further configured to generate a load under-voltage comparison signal according to the detection result, and the logic processing unit 111c generates a load response signal according to the under-voltage comparison signal and outputs the load response signal to the error amplifying module 112.

Further, in implementation, as shown in fig. 4, the first comparing unit 111a is implemented by using a comparator CMP1, a first input terminal of the comparator CMP1 is connected to the auxiliary winding of the transformer 12, a second input terminal of the comparator CMP1 receives the reference voltage, and an output terminal of the comparator CMP1 is connected to the logic processing unit 111 c.

Similarly, as shown in fig. 4, the second comparing unit 111b is implemented by a comparator CMP2, a first input terminal of the comparator CMP2 is connected to the auxiliary winding of the transformer 12, a second input terminal of the comparator CMP2 is connected to the sampling unit 111d, and an output terminal of the comparator CMP2 is connected to the logic processing unit 111 c.

Further, as an embodiment of the present disclosure, as shown in fig. 4, the sampling unit includes: a first resistor R2, a first switch element M1, and a first capacitor C4.

A first end of the first resistor R2 is connected to an auxiliary winding of the transformer 12 (not shown, refer to fig. 2), a second end of the first resistor R2 is connected to an input end of the first switch element M1, a control end of the first switch element M1 is connected to the logic processing unit 111C, an output end of the first switch element M1 is connected to a first end of the first capacitor C4 and the error amplification module 112, and a second end of the first capacitor C4 is connected to an equipotential end.

It should be noted that, in the embodiment of the present disclosure, the first switching element M1 is implemented by using an N-type transistor, a gate of the N-type transistor is a control terminal of the first switching element M1, a drain of the N-type transistor is an input terminal of the first switching element M1, and a source of the N-type transistor is an output terminal of the first switching element M1; of course, it will be understood by those skilled in the art that the N-type transistor is merely an example illustration of the first switching element M1, and the disclosure is not limited thereto.

Further, as an embodiment of the present disclosure, as shown in fig. 5, the current sampling module 116 includes: a second switching element M2 and a third switching element M3.

The control terminal and the input terminal of the second switching element M2 are commonly connected, and are connected to the control terminal of the third switching element M3 and the power switch module 119, the output terminal of the second switching element M2 and the input terminal of the third switching element M3 are both connected to an equipotential terminal, and the output terminal of the third switching element M3 is connected to the overcurrent protection module 117.

It should be noted that, in the embodiment of the present disclosure, the second switching element M2 and the third switching element M3 are implemented by using N-type transistors, gates of the N-type transistors are control terminals of the second switching element M2 and the third switching element M3, drains of the N-type transistors are input terminals of the second switching element M2 and the third switching element M3, and sources of the N-type transistors are output terminals of the second switching element M2 and the third switching element M3; of course, it will be understood by those skilled in the art that the N-type transistor is only an example of the second switching element M2 and the third switching element M3, and the disclosure is not limited thereto.

Further, as an embodiment of the present disclosure, as shown in fig. 5, the power switch module 119 includes: a fourth switching element M4, a fifth switching element M5, and a NAND gate NAND 1.

An input end of the fourth switching element M4 is connected to the switching tube 120 and an input end of the fifth switching element M5, a control end of the fourth switching element M4 is connected to the logic control module 114 and a first input end of the NAND gate NAND1, an output end of the fourth switching element M4 is connected to the current sampling module 116, a second input end of the NAND gate NAND1 is connected to the power supply starting module 118 (not shown in the drawings, refer to fig. 3), an output end of the NAND gate NAND1 is connected to a control end of the fifth switching element M5, and an output end of the fifth switching element M5 is connected to the energy storage filter capacitor C3 (not shown in the drawings, refer to fig. 2).

It should be noted that, in the embodiment of the present disclosure, the fourth switching element M4 and the fifth switching element M5 are implemented by using N-type transistors, gates of the N-type transistors are control terminals of the fourth switching element M4 and the fifth switching element M5, drains of the N-type transistors are input terminals of the fourth switching element M4 and the fifth switching element M5, and sources of the N-type transistors are output terminals of the fourth switching element M4 and the fifth switching element M5; of course, it will be understood by those skilled in the art that the N-type transistors are only exemplary illustrations of the fourth switching element M4 and the fifth switching element M5, and the disclosure is not limited thereto.

Further, as an embodiment of the present disclosure, as shown in fig. 2, the secondary rectification control module 13 includes: the secondary rectification control chip U2 and an output capacitor.

The primary rectification control chip U2 is connected to the secondary winding of the transformer 12, the output capacitor C5, and the load.

Specifically, the secondary rectification control chip U2 generates a charging voltage according to the charging energy, rectifies the charging voltage, and charges the load; the secondary rectification control chip U2 is further configured to detect an output voltage during a charging process, and feed back a detection result to the primary power control module 11 through the transformer 12; the output capacitor C5 stores energy according to the output voltage to supply power to the secondary rectification control chip U2.

In specific implementation, the first pin 1, the second pin 2, the third pin 3, and the fourth pin 4 of the secondary rectification control chip U2 are connected in common and are connected to the secondary coil of the transformer 12, the eighth pin 8 of the secondary rectification control chip U2 is connected to the secondary coil of the transformer 12 and the first end of the output capacitor C5, and the fifth pin 5, the sixth pin 6, and the seventh pin 7 of the secondary rectification control chip U2 are connected to ground in common and are connected to the output capacitor C5.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the secondary rectification control chip U2 includes: the power supply module 130, the voltage dividing module 131, the overvoltage protection module 132, the undervoltage protection module 133, the rectification start module 134, the rectification close module 135, the control module 136, the second driving module 137, and the switch module 138 are started.

The start power supply module 130 is connected to the output capacitor C5 (not shown in the drawings, please refer to fig. 2), the voltage dividing module 131, the overvoltage protection module 132, the undervoltage protection module 133, the rectification start module 134, the rectification shutdown module 135, the control module 136, and the second driving module 137, the overvoltage protection module 132 is connected to the output capacitor C5 and the voltage dividing module 131, the undervoltage protection module 133 is connected to the voltage dividing module 131 and the control module 136, the rectification start module 134 is connected to the control module 136, the rectification shutdown module 135 is connected to the control module 136, the control module 136 is connected to the second driving module 137, the second driving module 137 is connected to the switching module 138, and the switching module 138 is connected to the secondary coil of the transformer 12 (not shown in the drawings, please refer to fig. 2).

Specifically, the startup power supply module 130 supplies power to each module in the secondary rectification control chip U2 according to the output voltage; the voltage division module 131 performs voltage division sampling on the output voltage to obtain a divided voltage; when the divided voltage is higher than the overvoltage protection voltage, the overvoltage protection module 132 discharges the output voltage of the secondary rectification control chip U2; when the divided voltage is lower than the low-voltage protection voltage, the undervoltage protection module 133 outputs an undervoltage protection signal to the control module 136, and the control module 136 and the second driving module 137 control the switch module 138 to be in an off state according to the undervoltage protection module 133, so as to feed back the detection result to the primary power control module 11 through the transformer 12 (not shown in the figure, please refer to fig. 2).

The rectification start module 134 detects the voltage at the secondary coil end of the transformer 12, and when the voltage at the secondary coil end of the transformer 12 is not lower than the synchronous rectification start voltage threshold, outputs a rectification start signal to the control module 136, and the control module 136 and the second drive module 137 control the switch module 138 to be in a conduction working state according to the rectification start signal;

the rectification shutdown module 135 detects the voltage at the secondary coil end of the transformer 12, and outputs a rectification shutdown signal to the control module 136 when the voltage at the secondary coil end of the transformer 12 is not lower than the synchronous rectification shutdown voltage threshold, and the control module 136 and the second driving module 137 control the switching module 138 to be in a shutdown working state according to the rectification shutdown signal.

It should be noted that, in the embodiment of the present disclosure, fig. 6 only shows the connection relationship between the startup power supply module 130 and some modules in the secondary rectification control chip U2, and the specific connection relationship between the startup power supply module 130 and each module in the secondary rectification control chip U2 may be described with reference to the written text.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the voltage dividing module 131 includes voltage dividing resistors R3 and R4.

The first end of the voltage dividing resistor R3 is connected to the power-on module 130 and the overvoltage protection module 132, the second end of the voltage dividing resistor R3 is connected to the first end of the voltage dividing resistor R4 and the undervoltage protection module 133, and the second end of the voltage dividing resistor R4 is grounded.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the overvoltage protection module 132 includes a comparator CMP4, a switching element M6, and a resistor R5.

A first input end of the comparator CMP4 is connected to a second end of the voltage-dividing resistor R3, a second input end of the comparator CMP4 receives an overvoltage protection voltage, an output end of the comparator CMP4 is connected to a control end of the switch element M6, an output end of the switch element M6 is connected to an equipotential end, an input end of the switch element M6 is connected to a first end of the resistor R5, and a second end of the resistor R5 is connected to a first end of the voltage-dividing resistor R3 and the start power supply module 130.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the under-voltage protection module 133 includes a comparator CMP5, a first input terminal of the comparator CMP5 is connected to the second terminal of the voltage-dividing resistor R3 and the first terminal of the voltage-dividing resistor R4, a second input terminal of the comparator CMP5 receives the low-voltage protection voltage, and an output terminal of the comparator CMP5 is connected to the control module 136.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the rectification start module 134 includes a comparator CMP6, a first input terminal of the comparator CMP6 is connected to the input terminal of the switch module 138, a second input terminal of the comparator CMP6 receives the synchronous rectification start voltage, and an output terminal of the comparator CMP6 is connected to the control module 136.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the rectification shutdown module 135 includes a comparator CMP7, a first input terminal of the comparator CMP7 is connected to the input terminal of the switch module 138, a second input terminal of the comparator CMP7 receives the synchronous rectification shutdown voltage, and an output terminal of the comparator CMP7 is connected to the control module 136.

Further, as an embodiment of the present disclosure, as shown in fig. 6, the switch module 138 includes a switch element M7, a control terminal of the switch element M7 is connected to the second driving module 137, an input terminal of the switch element M7 is an input terminal of the switch module 138, and an output terminal of the switch element M7 is an output terminal of the switch module 138.

It should be noted that, in the embodiment of the present disclosure, the switching element M6 and the switching element M7 are implemented by using N-type transistors, gates of the N-type transistors are control terminals of the switching element M6 and the switching element M7, drains of the N-type transistors are input terminals of the switching element M6 and the switching element M7, and sources of the N-type transistors are output terminals of the switching element M6 and the switching element M7; of course, it will be understood by those skilled in the art that the N-type transistors are only illustrative of the switching elements M6 and M7, and the present disclosure is not limited thereto.

The following describes a specific operation principle of the power circuit 1 according to the embodiment of the present disclosure by taking the circuits shown in fig. 2 to fig. 6 as examples, and details are as follows:

first, as shown in fig. 2, the high voltage input module 10 composed of the rectifier diodes D1 to D4 and the current limiting resistor R1 rectifies the high voltage ac power, and outputs the rectified high voltage dc power to the filter circuit composed of the inductor L1, the capacitor C1 and the capacitor C2, and the filter circuit filters the high voltage dc power and outputs the filtered high voltage dc power.

When the filter circuit outputs the filtered high-voltage direct current, the primary coil of the transformer 12 starts the primary power control chip U1 according to the high-voltage direct current, and after the primary power control chip U1 is started, a stable working voltage is provided to the primary power control chip U1 through the energy storage filter capacitor C3. After the primary power control chip U1 operates, the primary power control chip U1 may directly sample the output voltage information coupled to the NA terminal of the auxiliary winding of the transformer T1, and adjust the operating frequency and duty ratio of the built-in high-voltage transistor to stabilize the output voltage and current, without the need of a start-up resistor, a feedback diode, and a current-sensing resistor in the existing power circuit.

When the primary power control chip U1 adjusts the operating frequency and duty ratio of the built-in high-voltage transistor to output a stable output voltage and current from the energy accumulated on the transformer 12, the secondary rectification control chip U2 detects the NS waveform of the secondary winding of the transformer 12 through the first pin 1, the second pin 2, the third pin 3, and the fourth pin 4 to implement a synchronous rectification function, and further provides a required charging voltage to the load to implement charging of the load; in addition, the secondary rectification control chip U2 can perform output detection and feed back to the primary power control chip U1 through the transformer 12 to prevent output overvoltage or undervoltage.

Further, referring to fig. 3, when the primary power controller U1 is operating, the power switch module 119 and the power start module 118 supply power to the primary power controller U1 under the control and driving actions of the driver module 115 and the logic controller module 114, so that the primary power controller U1 can operate normally; in addition, the power up module 118 may generate various voltage and current references as needed within the primary power control chip U1.

Further, the current sampling module 116 is configured to sample a current of the primary side power loop (a loop formed by the primary winding of the transformer 12 in fig. 2 and the switching tube 120, the switching element M4, and the switching element M2 in fig. 5) and transmit the current to the over-current protection module 117, so that the over-current protection module 117 generates a corresponding over-current protection control signal according to the current of the primary side power loop and the over-current protection reference current, and transmits the over-current protection control signal to the logic control module 114; the voltage sampling module 111 directly samples a voltage signal which can reflect an output voltage on an auxiliary coil (feedback winding) of the external transformer 12 through a first pin 1(FB pin) of the primary power control chip U1, that is, the voltage sampling module 111 samples a coupling voltage at an auxiliary coil end of the transformer 12 to obtain a sampling voltage, and sends the sampling voltage to the error amplification module 112 for comparison, the error amplification module 112 generates an error amplification signal after comparing the sampling voltage with a reference voltage, and transmits the error amplification signal to the constant voltage constant current control module 113; the constant voltage and constant current control module 113 generates a control signal according to the error amplification signal and outputs the control signal to the logic control module 114, so that the logic control module 114 generates a first switch control signal according to the control signal and the overcurrent protection control signal output by the overcurrent protection module 117, and sends the switch control signal to the first driving module 115, so that the first driving module 115 controls the on-off frequency of the switching tube 120 according to the first switch control signal, and the power circuit 1 outputs a stable charging voltage.

Further, the voltage sampling module 111 may also detect a control signal mapped to the feedback winding by the secondary winding of the transformer 12, and transmit the control signal to the logic control module 114, so that the logic control module 114 and the driving module 115 control the on/off of the switching tube 120 according to the control signal, so as to implement a partial secondary control function. For example, when the secondary rectification control chip U2 feeds back the output voltage of the power circuit 1 to the primary power control chip U1 through the transformer 12 and is under-voltage, the voltage sampling module 111 generates a load response signal according to the detection result fed back by the secondary rectification control chip U2, and sends the load response signal to the error amplification module 112; the error amplifying module 112 generates a load response amplifying signal according to the load response signal and sends the load response amplifying signal to the constant voltage constant current control module 113, the constant voltage constant current control module 113 generates a load response control signal according to the load response amplifying signal and outputs the load response control signal to the logic control module 114, the logic control module 114 generates a second switch control signal according to the load response control signal, and the first driving module 115 controls the on-off frequency of the switching tube 120 according to the second switch control signal to realize load response.

Further, as shown in fig. 4, when the voltage sampling module 111 operates, the secondary undervoltage protection signal detection comparator CMP1 detects a signal generated by the secondary rectification control chip U2 (not shown in the figure, please refer to fig. 2) and transmitted to the primary power control chip U1 by the transformer 12 to generate a load undervoltage comparison signal, and sends the load undervoltage comparison signal to the logic processing unit 111c, and the logic processing unit 111c identifies the undervoltage comparison signal to generate a load response signal QR, and then outputs the load response signal QR to the error amplification module 112, so that the error amplification module 112 and its rear end circuit work together to realize the load response between the primary and secondary circuits.

In addition, the comparator CMP1 may further generate a first sampling comparison signal according to the coupling output voltage of the complex auxiliary winding end of the transformer, and output the first sampling comparison signal to the logic processing unit 111C, and the logic processing unit 111C generates a first sampling control signal according to the first sampling comparison signal, so as to control the switch M1 in the switched capacitor sampling circuit composed of the resistor R2, the switch M1, and the capacitor C4 to be turned on, and further sample the voltage of the FB pin, so as to obtain a sampling voltage; it should be noted that, because the ratio of the feedback winding to the secondary winding of the transformer is set to be small, a voltage dividing resistor is not needed, and the chip can realize the voltage sampling function by using a low-voltage process.

Further, the comparator CMP2 is a self-offset comparator, and its input terminals are a voltage signal at the FB terminal and a voltage signal sampled by the switch RC, specifically, during operation, the comparator CMP2 generates a second sampling comparison signal according to the coupling output voltage and the sampling voltage, and outputs the second sampling comparison signal to the logic processing unit 111C, and the logic processing unit 111C generates a second sampling control signal according to the second sampling comparison signal, so as to control the switch M1 in the switched capacitor sampling circuit composed of the resistor R2, the switch M1, and the capacitor C4 to be turned off, and further stop sampling the coupling output voltage.

Further, as shown in fig. 5, the pin C is connected to the primary coil of the external transformer, which is the fifth pin 5, the sixth pin 6, the seventh pin 7, and the eighth pin 8 of the primary power control chip U1, the switching tube 120 is a high voltage power transistor, the resistor Rcb is a high voltage resistor between the collector and the base of the switching tube 120, which may be integrated by device process or added outside the chip, and this is not limited specifically here. When the primary power control chip U1 works, the specific power supply process of the primary power control chip U1 is: the high-voltage end outputs a base driving current to the switch tube 120 through the resistor Rcb, at this time, the switch tube 12 is turned on, the logic control module 114 controls the switch element M4 to be turned off, and the logic control module 114, the power starting module 118 and the NAND gate NAND1 jointly control the switch element M5 to be turned on, at this time, the emitter current of the switch tube 120 can flow to the VDD pin, i.e., the second pin 2, of the primary power control chip U1 through the switch tube M5 until the primary power control chip U1 is turned on. When the primary power control chip U1 is operating, if the primary power control chip U1 detects that the VDD voltage is low, the logic control module 114 will control the switch M4 to be continuously turned off for a certain period of time when the switch tube 120 is turned on, and control the switch M5 to be continuously turned on in conjunction with the power starting module 118 and the NAND gate NAND1, so that the current passes through the supply capacitor C3 of the VDD pin to the ground, forming a current path and charging the VDD capacitor, and further supplying power to the primary power control chip U1, and when the primary power control chip U1 detects that the VDD voltage is too high, the logic control module 114 will control the switch M4 to be turned on for a certain period of time when the switch tube 120 is turned on, and control the switch M5 to be continuously turned off in conjunction with the power starting module 118 and the NAND gate 1, so as to break the current path between the VDD pin and the supply capacitor C3; it should be noted that, in the embodiment of the present disclosure, since the power supply process is performed by using the periodic main-side inductor current, and when the output is idle, the operating frequency of the power circuit is very low, the power supply period is extended, which may cause VDD under-voltage, so that the primary power control chip U1 will control the switching element M5 to be turned on to supply power to VDD during the time when the switching element M4 is turned off, and thus the primary power control chip U1 can also implement the function of enabling power supply without an external starting resistor and a feedback power supply circuit.

Further, as shown in fig. 5, the specific working mode of the current sampling module 116 is as follows: the switching element M2 and the switching element M3 form a current mirror, and further form a main side current sample with the switching element 120, that is, when the switching element 120 is turned on with the switching element M4 and the switching element M2, the current flowing through the transformer 12 is the same as that flowing through the switching element M4 and the switching element M2, and since the switching element M3 and the switching element M3 are current mirrors, the main side current can be scaled down by mirroring to obtain a corresponding current sample result, and the over-current protection comparator CMP3 can compare the current sample result with an internal over-current reference voltage to generate an over-current protection signal, so as to implement over-current protection.

Further, as shown in fig. 6, the specific working principle of the secondary rectification control chip U2 is as follows: the starting power supply module 130 supplies power to each module in the secondary rectification control chip U2 according to the output voltage, that is, supplies the voltage required by the operation of the secondary rectification control chip U2; the output voltage is divided by a divided voltage consisting of resistors R3 and R4 to obtain a divided voltage; the comparator CMP4 is a VCC overvoltage protection comparator, and when the voltage at the VCC terminal exceeds an overvoltage protection voltage threshold, the comparator CMP1 turns over and generates a protection signal to control the switching element M6 to be turned on, so as to discharge VCC; the comparator CMP5 is a VCC undervoltage protection comparator, and when the load is dynamically switched or the output voltage undershoots, the comparator CMP5 generates a protection signal according to the detected output voltage change, and transmits the protection signal to the control module 136 to implement response protection, for example, when the divided voltage is lower than the low-voltage protection voltage, the comparator CMP5 outputs an undervoltage protection signal to the control module 136, and the control module 136 and the second driving module 137 control the switching element M7 to be in an off working state according to the undervoltage protection module, so as to feed back the detection result to the primary power control module 11 through the transformer 12 (not shown in the figure, please refer to fig. 2).

Further, the comparator CMP6 is a synchronous rectification start comparator, when the voltage of the VD pin, that is, the voltages at the first pin 1, the second pin 2, the third pin 3, and the fourth pin 4 of the secondary rectification control chip U2 reach a synchronous rectification start voltage threshold, the comparator CMP6 inverts and generates a rectification start signal to transmit to the control module 136, the control module 136 and the second driving module 137 control the switching element M7 to be turned on according to the synchronous rectification start signal, the comparator CMP7 is a synchronous rectification stop comparator, when the voltage of the VD pin reaches the synchronous rectification stop voltage threshold, the comparator CMP7 inverts and generates a rectification stop signal to transmit to the control module 136, and the control module 136 and the second driving module 137 control the switching element M7 to be turned off according to the synchronous rectification stop signal, thereby implementing the secondary synchronous rectification of the power circuit 1.

It should be noted that, in the embodiment of the present disclosure, when the control module 136 controls the switch element M7 to be in the off state according to the under-voltage protection module at the second driving module 137, so as to feed back the detection result to the primary power control module 11 through the transformer 12, the control module 136 may generate a pulse control signal in the safety interval of the synchronous rectification off time, and control the switch element M7 to be turned on for a short time according to the pulse control signal with the second driving module 137, so as to transmit the output under-voltage signal to the primary power control chip U1 through the transformer 12, and the primary power control chip U1 will respond after detecting the output under-voltage signal, so as to implement the load response function of secondary detection and control.

In addition, in the embodiment of the present disclosure, on one hand, the secondary rectification control chip U2 has certain power consumption, and on the other hand, the secondary rectification control chip U2 can control the power circuit to operate at an extremely low operating frequency when the power circuit 1 is idle, so that the idle output power is extremely low, and therefore, the secondary rectification control chip U2 omits a dummy load resistor, and simplifies the circuit structure of the power circuit; in addition, due to the load response function of the secondary rectification control chip U2, when the power circuit 1 operates at a very low operating frequency, if a load is suddenly switched on, the secondary rectification control chip U2 can also detect and feed back the variation of the output voltage at that time, and transmit the variation to the primary power control chip U1, so that the primary power control chip U1 responds to the load variation, and excellent load response performance is achieved.

In the embodiment of the present disclosure, the power circuit 1 provided by the present disclosure uses the primary power control chip U1 and the secondary rectification control chip U2, so that compared with the existing power circuit, the power circuit 1 does not need a chip start resistor, a feedback power supply network, a feedback voltage-dividing resistor, a current detection resistor and a dummy load resistor, and reduces a large number of peripheral elements, thereby greatly simplifying the circuit structure of the whole power circuit, so that the circuit structure of the power circuit is simpler, the scheme integration level is high while the design is facilitated, the charger miniaturization is facilitated, the scheme cost is greatly reduced, and the integration level is high, thereby further bringing higher reliability and safety.

Further, the present disclosure also provides a power supply apparatus including the power supply circuit 1. It should be noted that, since the power circuit of the power supply device provided in the embodiment of the present disclosure is the same as the power circuit 1 shown in fig. 1 to 6, reference may be made to the foregoing detailed description about fig. 1 to 6 for a specific operating principle of the power circuit 1 in the power supply device provided in the embodiment of the present disclosure, and details are not repeated here.

In the embodiment of the disclosure, the power circuit high-voltage input module provided by the disclosure converts the accessed high-voltage alternating current into high-voltage direct current, the primary power control module samples the coupling output voltage of the auxiliary coil end of the transformer, controls the transformer to generate charging energy according to the high-voltage direct current according to the sampling result, and the secondary rectification control module generates charging voltage according to the charging energy, rectifies the charging voltage and charges the charging voltage to a load; the secondary rectification control module is also used for detecting the output voltage in the charging process, and feeding the detection result back to the primary power control module through the transformer, and the primary power control module adjusts the input power of the transformer according to the detection result, so that the power circuit is simple in circuit structure while effectively charging the load, the size, the number of components and electronic garbage generated by the power circuit are reduced, and the cost is low.

The above examples are only intended to illustrate the technical solutions of the present disclosure, not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present disclosure, and are intended to be included within the scope of the present disclosure.

Claims

1. A power supply circuit, characterized in that the power supply circuit comprises:

the high-voltage input module converts the accessed high-voltage alternating current into high-voltage direct current, the primary power control module samples the coupling output voltage of the auxiliary coil end of the transformer, the transformer is controlled to generate charging energy according to the high-voltage direct current according to the sampling result, and the secondary rectification control module generates charging voltage according to the charging energy, rectifies the charging voltage and then charges the load; the secondary rectification control module is also used for detecting the output voltage in the charging process and feeding back the detection result to the primary power control module through the transformer, and the primary power control module adjusts the input power of the transformer according to the detection result;

the primary power control module includes:

the primary power control chip and the energy storage filter capacitor;

the primary power control chip is connected with a primary coil, an auxiliary coil and the energy storage filter capacitor of the transformer, and the energy storage filter capacitor is connected with the auxiliary coil of the transformer;

the primary power control chip generates a power supply voltage according to the voltage of the primary coil end of the transformer, and the energy storage filter capacitor stores energy according to the power supply voltage so as to provide working voltage for the primary power control chip;

the primary power control chip is also used for sampling the coupling output voltage of the auxiliary coil end of the transformer, controlling the transformer to generate charging energy according to the high-voltage direct current according to the sampling result, and adjusting the input power of the transformer according to the detection result fed back by the secondary rectification control module;

the primary power control chip includes:

the device comprises a voltage sampling module, an error amplification module, a constant voltage and constant current control module, a logic control module, a first driving module, a current sampling module, an overcurrent protection module, a power supply starting module, a power supply switch module and a switch tube;

the voltage sampling module is connected with an auxiliary coil of the transformer and the error amplification module, the error amplification module is connected with the constant-voltage constant-current control module, the constant-voltage constant-current control module is connected with the logic control module, the logic control module is connected with the overcurrent protection module, the power switch module and the first driving module, the first driving module is connected with the switch tube, the switch tube is connected with the power switch module and a primary coil of the transformer, the power switch module is connected with the power starting module and the energy storage filter capacitor, and the current sampling module is connected with the power switch module and the overcurrent protection module;

when the power circuit is powered on, the switch tube is conducted according to the voltage of the primary coil end of the transformer, and when the primary power control chip works, the logic control module and the power starting module control the power switch module to be in a first conduction state, so that the power switch module outputs the power supply voltage; the power supply starting module detects the power supply voltage, controls the power supply switch module to be continuously in a first conduction state with the logic control module when the power supply voltage is lower than a first preset power supply voltage, and controls the power supply switch module to be continuously in a second conduction state with the logic control module when the power supply voltage is higher than a second preset power supply voltage;

when the switching tube is switched on and the power switch module is in a second conduction state, the current sampling module samples the current of the primary coil end of the transformer and feeds a current sampling result back to the overcurrent protection module, the overcurrent protection module generates an overcurrent protection signal according to the current sampling result and overcurrent reference voltage, and the logic control module generates an overcurrent protection control signal to the first driving module according to the overcurrent protection signal;

the voltage sampling module samples the coupling output voltage of the auxiliary coil end of the transformer to obtain a sampling voltage, the error amplification module compares the sampling voltage with a reference voltage to generate an error amplification signal, the constant voltage and constant current control module generates a control signal according to the error amplification signal, the logic control module generates a first switch control signal according to the control signal and the overcurrent protection control signal, and the first driving module controls the on-off frequency of the switching tube according to the first switch control signal.

2. The power supply circuit of claim 1, wherein the voltage sampling module is further configured to generate a load response signal according to the detection result, the error amplification module generates a load response amplification signal according to the load response signal, the constant voltage and constant current control module generates a load response control signal according to the load response amplification signal, the logic control module generates a second switch control signal according to the load response control signal, and the first driving module controls the on-off frequency of the switching tube according to the second switch control signal.

3. The power supply circuit of claim 2, wherein the voltage sampling module comprises:

the device comprises a first comparison unit, a second comparison unit, a logic processing unit and a sampling unit;

the first comparing unit is connected with an auxiliary coil of the transformer and the logic processing unit, the second comparing unit is connected with the auxiliary coil of the transformer, the logic processing unit and the sampling unit, the logic processing unit is connected with the sampling unit and the error amplifying module, and the sampling unit is connected with the auxiliary coil of the transformer and the error amplifying module;

the first comparison unit generates a first sampling comparison signal according to the coupling output voltage, the logic processing unit generates a first sampling control signal according to the first sampling comparison signal, and the sampling unit samples the coupling output voltage according to the first sampling control signal to output the sampling voltage; the second comparison unit generates a second sampling comparison signal according to the coupling output voltage and the sampling voltage, the logic processing unit generates a second sampling control signal according to the second sampling comparison signal, and the sampling unit stops sampling the coupling output voltage according to the second sampling control signal;

the first comparison unit is further configured to generate a load under-voltage comparison signal according to the detection result, and the logic processing unit generates the load response signal according to the under-voltage comparison signal and outputs the load response signal to the error amplification module.

4. The power supply circuit of claim 3, wherein the sampling unit comprises:

a first resistor, a first switch element and a first capacitor;

the first end of the first resistor is connected with the auxiliary coil of the transformer, the second end of the first resistor is connected with the input end of the first switch element, the control end of the first switch element is connected with the logic processing unit, the output end of the first switch element is connected with the first end of the first capacitor and the error amplification module, and the second end of the first capacitor is connected with the equipotential end.

5. The power supply circuit of claim 1, wherein the current sampling module comprises:

a second switching element and a third switching element;

the control end and the input end of the second switch element are connected in common and are connected with the control end of the third switch element and the power switch module, the output end of the second switch element and the input end of the third switch element are both connected with the equal potential end, and the output end of the third switch element is connected with the overcurrent protection module.

6. The power supply circuit of claim 1, wherein the power switch module comprises:

a fourth switching element, a fifth switching element and a nand gate;

the input end of the fourth switching element is connected with the input ends of the switching tube and the fifth switching element, the control end of the fourth switching element is connected with the logic control module and the first input end of the NAND gate, the output end of the fourth switching element is connected with the current sampling module, the second input end of the NAND gate is connected with the power supply starting module, the output end of the NAND gate is connected with the control end of the fifth switching element, and the output end of the fifth switching element is connected with the energy storage filter capacitor.

7. The power supply circuit of claim 1, wherein the secondary rectification control module comprises:

the secondary rectification control chip and the output capacitor;

the secondary rectification control chip is connected with a secondary coil of the transformer, the output capacitor and the load;

the secondary rectification control chip generates a charging voltage according to the charging energy, rectifies the charging voltage and charges the load; the secondary rectification control chip is also used for detecting the output voltage in the charging process and feeding back the detection result to the primary power control module through the transformer; and the output capacitor stores energy according to the output voltage so as to supply power to the secondary rectification control chip.

8. The power supply circuit of claim 7, wherein the secondary rectification control chip comprises:

the power supply device comprises a starting power supply module, a voltage division module, an overvoltage protection module, an undervoltage protection module, a rectification starting module, a rectification closing module, a control module, a second driving module and a switch module;

the starting power supply module is connected with the output capacitor, the voltage dividing module, the overvoltage protection module, the undervoltage protection module, the rectification starting module, the rectification closing module, the control module and the second driving module, the overvoltage protection module is connected with the output capacitor and the voltage dividing module, the undervoltage protection module is connected with the voltage dividing module and the control module, the rectification starting module is connected with the control module, the rectification closing module is connected with the control module, the control module is connected with the second driving module, the second driving module is connected with the switch module, and the switch module is connected with a secondary coil of the transformer;

the starting power supply module supplies power to each module in the secondary rectification control chip according to the output voltage; the voltage division module performs voltage division sampling on the output voltage to acquire a divided voltage; the overvoltage protection module discharges the output voltage of the secondary rectification control chip when the divided voltage is greater than the overvoltage protection voltage; the undervoltage protection module outputs an undervoltage protection signal to the control module when the divided voltage is lower than a low-voltage protection voltage, and the control module and the second driving module control the switch module to be in a turn-off working state according to the undervoltage protection module so as to feed the detection result back to the primary power control module through the transformer;

the rectification starting module detects the voltage of the secondary coil end of the transformer, when the voltage of the secondary coil end of the transformer is not lower than a synchronous rectification starting voltage threshold value, a rectification starting signal is output to the control module, and the control module and the second driving module control the switch module to be in a conduction working state according to the rectification starting signal;

the rectification closing module detects the voltage of the secondary coil end of the transformer, when the voltage of the secondary coil end of the transformer is not lower than a synchronous rectification closing voltage threshold value, a rectification closing signal is output to the control module, and the control module and the second driving module control the switch module to be in a turn-off working state according to the rectification closing signal.

9. A power supply device characterized in that it comprises a power supply circuit according to any one of claims 1 to 8.