CN217388544U

CN217388544U - Power supply circuit and electronic equipment

Info

Publication number: CN217388544U
Application number: CN202220713558.4U
Authority: CN
Inventors: 黎宇
Original assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd; Hefei Shiyan Electronic Technology Co Ltd
Current assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd; Hefei Shiyan Electronic Technology Co Ltd
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2022-09-06
Anticipated expiration: 2032-03-29

Abstract

The application provides a power supply circuit and electronic equipment, wherein a control circuit is used for controlling a dummy load circuit to be connected or disconnected with a first load according to the voltage value of a second voltage output by a second primary side circuit, and when the second voltage is smaller than a preset threshold value, the dummy load circuit is connected with a first secondary side circuit to provide load current for the first load; and when the second voltage is greater than the preset threshold value, disconnecting the connection relation between the dummy load circuit and the first secondary side circuit. Therefore, the invalid energy loss of the power supply circuit can be reduced under the condition of keeping the normal and stable operation of the power supply circuit.

Description

Power supply circuit and electronic equipment

Technical Field

The application relates to the technical field of electronic circuits, in particular to a power supply circuit and electronic equipment.

Background

The power supply circuit is an essential circuit in the electronic device, and can process the acquired external input voltage and supply power to a load in the electronic device.

In the related art, an input voltage obtained by a first primary side circuit of a power supply circuit may be processed by a voltage change of a transformer, a first voltage is output to a first load through a first secondary side winding, a second voltage is output to a voltage conversion circuit through a second primary side circuit, and a third voltage is output to a second load after the second voltage is processed by the voltage conversion circuit. The power supply circuit is also provided with a dummy load circuit, when the second voltage is low due to the conditions that the first load is light load, the second load is heavy load and the like, the dummy load circuit can provide load current for the first load, so that the second voltage is improved, and the stability of the third voltage output to the second load after the voltage conversion circuit processes the second voltage is further ensured.

However, in the related art, when the second voltage and the third voltage are normal, the dummy load circuit still outputs a load current, causing an ineffective energy loss to the power supply circuit.

SUMMERY OF THE UTILITY MODEL

The application provides a power supply circuit and electronic equipment, under the condition that keeps normal stable work of power supply circuit, can also reduce power supply circuit's invalid energy loss.

A first aspect of the present application provides a power supply circuit, including: the device comprises a first primary side circuit, a transformer, a first secondary side circuit, a second primary side circuit, a voltage conversion circuit, a dummy load circuit and a control circuit; the first primary side circuit is connected with the first secondary side circuit through the transformer, and the transformer is connected with the voltage conversion circuit through the second primary side circuit; the input voltage passes through the first primary side circuit, the transformer and the first secondary side circuit, and a first voltage is output to a first load; the input voltage passes through the first primary side circuit, the transformer and the second primary side circuit and outputs a second voltage to the voltage conversion circuit, and the voltage conversion circuit converts the second voltage and outputs a third voltage to a second load; the control circuit is connected with the second primary side circuit and the dummy load circuit, and the control circuit controls the dummy load circuit to be connected or disconnected with the first secondary side circuit according to the second voltage.

In an embodiment of the first aspect of the present application, when the second voltage is greater than a preset threshold, the control circuit controls the dummy load circuit to be disconnected from the first secondary circuit; when the second voltage is smaller than the preset threshold value, the control circuit controls the dummy load circuit to be connected with the first secondary circuit; when the second voltage is equal to the preset threshold, the control circuit controls the dummy load circuit to be disconnected or connected with the first secondary circuit.

In an embodiment of the first aspect of the present application, the control circuit includes: the detection circuit, the isolation circuit and the switch circuit; the detection circuit is connected with the second primary side circuit, the detection circuit is connected with the switch circuit through the isolation circuit, and the switch circuit is connected with the dummy load circuit in series; the detection circuit is used for controlling the switch-off or the switch-on of the switch circuit through the isolation circuit according to a second voltage, so that the dummy load circuit is disconnected or connected with the first secondary circuit.

In an embodiment of the first aspect of the present application, the detection circuit includes: the circuit comprises a first resistor, a second resistor, a third resistor and a first switch; the first end of the first resistor is connected with the second primary side circuit and the first end of the third resistor, the second end of the first resistor is connected with the first end of the second resistor and the control end of the first switch, the second end of the third resistor is connected with the isolation circuit, the first end of the first switch is connected with the isolation circuit, and the second end of the first switch is grounded.

In an embodiment of the first aspect of the present application, the switching circuit includes: a fourth resistor, a fifth resistor and a second switch; the first end of the fifth resistor is connected with the first secondary side circuit, the second end of the fifth resistor is connected with the isolation circuit, the first end of the fourth resistor and the control end of the second switch, the second end of the fourth resistor is grounded, the first end of the second switch is connected with the dummy load circuit, and the second end of the second switch is grounded.

In an embodiment of the first aspect of the present application, the isolation circuit includes: an optical coupler; the first input end of opto-coupler is connected the second end of third resistance, the second input end of opto-coupler is connected the first end of first switch, the first output end of opto-coupler is connected the second end of fifth resistance the first end of fourth resistance with the control end of second switch, the second output end ground connection of opto-coupler.

In an embodiment of the first aspect of the present application, the dummy load circuit includes: at least one dummy load resistor.

In an embodiment of the first aspect of the present application, the second primary side circuit further outputs a fourth voltage to the driving circuit of the first primary side circuit.

In an embodiment of the first aspect of the present application, the control circuit controls a resistance value of the dummy load circuit according to the second voltage.

A second aspect of the application provides an electronic device comprising a supply circuit as claimed in any one of the first aspect of the application.

According to the power supply circuit and the electronic device provided by the embodiment of the application, the control circuit can be used for controlling the dummy load circuit to be connected or disconnected with the first load according to the voltage value of the second voltage output by the second primary side circuit, so that under the conditions that the first load is light load, the second load is heavy load and the like, and when the second voltage is smaller than a preset threshold value, the dummy load circuit is connected with the first secondary side circuit to provide load current for the first load, and the second voltage and a third voltage subsequently provided for the second load can be kept normal and stable; when the second voltage is greater than the preset threshold value, the connection relation between the dummy load circuit and the first secondary side circuit is disconnected, the invalid energy loss of the dummy load circuit when the load current does not need to be supplied to the first load is reduced, the whole control process is more intelligent, the circuit structure is simple, the invalid energy loss of the power supply circuit is reduced under the condition that the normal and stable work of the power supply circuit is kept, and the power supply circuit and the electronic equipment where the power supply circuit is located are ensured to meet certain energy-saving requirements.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a schematic diagram of an application scenario of the present application;

FIG. 2 is a schematic diagram of a power supply circuit in the related art;

FIG. 3 is a schematic circuit diagram of a power supply circuit;

FIG. 4 is a schematic diagram of another power supply circuit in the related art;

fig. 5 is a schematic structural diagram of an embodiment of a power supply circuit provided in the present application;

fig. 6 is a schematic structural diagram of an embodiment of a control circuit provided in the present application;

fig. 7 is a schematic circuit diagram of an embodiment of a control circuit provided in the present application;

fig. 8 is a schematic diagram of an operation timing sequence of the power supply circuit provided in the present application.

Detailed Description

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

The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Fig. 1 is a schematic diagram of an application scenario of the present application, as shown in fig. 1, a power supply circuit 11 provided in the present application is applied to an electronic device 10, the electronic device 10 may be any device such as a mobile phone, a computer, a tablet computer, an interactive tablet, an intelligent home appliance, and the like, the electronic device 10 includes one or more loads, which are denoted as a first load 121 and a second load 122 … …, and the power supply circuit 11 may be configured to obtain an external input voltage, and output a voltage to each load after performing processing such as rectification, filtering, voltage conversion, and the like on the voltage, so as to supply power to the loads.

Fig. 2 is a schematic structural diagram of a power supply circuit in the related art, and fig. 2 shows an implementation manner of the power supply circuit 11 in fig. 1, where the power supply circuit 11 includes: the circuit comprises a first primary side circuit 111, a transformer 112, a first secondary side circuit 113, a second primary side circuit 114, a driving circuit 115, a voltage conversion circuit 116 and a feedback circuit 117.

One end of the first primary circuit 111 is used to obtain an external input voltage V0, and the other end is connected to one end of the output circuit 113 through the transformer 112, and is used to process the input voltage and input the processed input voltage into the transformer 112. The first secondary circuit 113 may output the first voltage V1, which is obtained by transforming the first load 121, to the transformer 112.

The driving Circuit 115 may be configured to control the first primary Circuit 111 to process the acquired input voltage and output the processed input voltage to the transformer 112, and the driving Circuit may be a control Integrated Circuit (IC), a driving IC, or the like, and in a specific implementation process, the driving Circuit 115 may also be understood as a part of the first primary Circuit 111 or may be configured independently of the first primary Circuit 111.

The second primary circuit 114 may be configured to provide the fourth voltage V4 to the driving circuit 115, so as to supply power to the driving circuit 115, control the driving circuit 115 to start and operate, and the like. Meanwhile, the second primary side circuit 114 may further provide the second voltage V2 to the circuit converting circuit 116, and after the voltage converting circuit 116 performs the voltage conversion process on the second voltage V2, the third voltage V3 is provided to the second load 122. The voltage converting circuit 116 may be a Low Dropout Regulator (LDO) or a Direct Current converter (DC/DC) circuit.

The feedback circuit 117 may be configured to obtain a voltage at an output end of the first secondary circuit 1131, and send a feedback signal FB to the driving circuit 115 according to the current output voltage, so that the driving circuit 115 can adjust the voltage output by the first primary circuit 111 to the transformer 112 according to the feedback signal FB, thereby adjusting the voltage output by the first secondary circuit 1131 to the first load 121.

The embodiments of the present application do not limit the specific implementation of the primary side circuit and the secondary side circuit, for example, the primary side circuit may sequentially include: a rectifier module, a Power Factor Correction (PFC) module, an LLC module, and the like. In addition, the transformer can further comprise other primary windings and secondary windings, wherein the primary windings are used for being connected with the primary circuit, the secondary windings are used for being connected with the secondary circuit and the like.

Fig. 3 is a schematic diagram of a circuit structure of a power supply circuit, which shows a specific implementation manner of a partial circuit structure in the power supply circuit of fig. 2, and as shown in fig. 3, a first primary circuit 111 is connected to a primary winding numbered 3-5 of a transformer 112, a second primary circuit 114 is connected to a primary winding numbered 1-2 of the transformer 112, and a first secondary circuit 1131 is connected to a secondary winding numbered 7-8 of the transformer. When the first primary circuit 111 sends the acquired external input voltage to the primary winding of the transformer 112, the first secondary circuit 1131 may output a first voltage V1 to the subsequently connected first load 121 through the secondary winding under the action of the magnetic core of the transformer, where fig. 3 takes as an example that the first voltage V1 output by the first secondary circuit 1131 is 12V. Subsequently, the voltage on the secondary winding of the transformer generates a voltage on the secondary winding 114 through the magnetic core, and the fourth voltage V4 can be provided to the driving circuit 115 by the secondary winding 114 through the rectification and filtering process of the transformer. Meanwhile, the second primary side circuit 114 may further provide the second voltage V2 to the voltage conversion circuit 116, and then the voltage conversion circuit 116 performs voltage conversion and the like on the second voltage V2 to provide the third voltage V3 to the second load 122.

The power supply circuit using flyback power supply topology as shown in fig. 2 and 3 can be applied to the electronic device as shown in fig. 1 for providing multiple output voltages to multiple loads in the electronic device. In the power supply circuit, since the voltage on each winding of the transformer changes in proportion to the number of turns on the winding, the power supply circuit can set the voltage output by the transformer to the load through the winding and the primary circuit/secondary circuit by adjusting the number of turns of the transformer. Ideally, if one of the output voltages of the transformer is regulated, the voltage drop across the other windings of the transformer scales in terms of the number of turns and remains stable. For example, when the transformer is ideal and the diode drop is negligible, the voltage output by the transformer can be kept stable in an operation Mode such as Continuous Conduction Mode (CCM). However, due to the non-ideality caused by the leakage inductance and the coil resistance of the transformer and the non-negligible voltage drop of the diode, when the load of the output voltage of the power supply circuit changes, the output voltage does not change according to the number of turns of the transformer, and the output voltage is unstable.

For example, assuming that the power supply circuit shown in fig. 3 is applied to a heat pump integrated board, the first voltage V1 output by the power supply circuit is 12V, the load connected to the subsequent stage can dynamically change within a range of 0.02A-1A, and since the accuracy range of the first voltage output by the power supply circuit to the load connected to the subsequent stage requires within a range of ± 3%, the first voltage V1 can adopt a closed-loop feedback control manner, and the feedback circuit 117 sends a feedback signal to the driving circuit 115 according to the voltage output by the first secondary circuit 1131, so that the driving circuit 115 controls the voltage input by the first primary circuit 111 to the transformer 112, thereby implementing adjustment of the first voltage output by the first secondary circuit 1131.

The fourth voltage V4 output by the power supply circuit supplies power to the driving circuit 115, and the load is small and the voltage range only needs to satisfy the working voltage of the driving circuit 115, so the accuracy requirement on the fourth voltage V4 output by the power supply circuit is low, and an open-loop non-feedback control mode can be adopted.

The second voltage V2 output by the power supply circuit is used to supply power to loads such as a drive, a relay, and an MCU on a strong power side, and these loads will continue to operate after being powered on, and the current variation range of the loads is about 0.2A and the accuracy requirement is within a range of ± 3%, therefore, the power supply circuit may be configured with the voltage conversion circuit 116 to perform voltage conversion and voltage stabilization on the second voltage V2, and then output a more stable third voltage V3 to the subsequent loads.

Further, when the voltage conversion circuit 116 is an LDO, the LDO needs to satisfy a certain voltage difference Vd between the input voltage Vldo _ in _ min (the second voltage V2) and the output voltage VIdo _ out (the third voltage V3) when the LDO operates, and the LDO can output a stable voltage, that is, the input voltage Vldo _ in _ min and the output voltage VIdo _ out need to satisfy Vd ═ Vldo _ in _ min-VIdo _ out. Wherein the voltage difference Vd can be varied within a range of 1.5V-2V according to the intrinsic device parameters.

However, the power supply circuits shown in fig. 2 to fig. 3 have a problem of load cross regulation rate, such that the input voltage Vldo _ in _ min when the LDO is operating is not completely related to the number of turns of the transformer, but varies with the load, and thus the voltage VIdo _ out output by the LDO is unstable, which affects the third voltage V3 provided by the power supply circuit to the second load 122.

TABLE 1

	Case 1	Case 2	Case 3
				V1 output tape carrier	0.05A	0.2A	1A
V3 output tape carrier	0.2A	0.2A	0.2A
				V1 output voltage	12.078V	12.069V	12.068V
V2 output voltage	9.42V	17.5V	18.8V
				V3 output voltage	7.785V	15.103V	15.12V

For example, table 1 is a schematic diagram of the output voltage and the load of the power supply circuit in fig. 3, and it can be seen from a column of case 1 that, when the load current output by the power supply circuit to the first load 121 is 0.05A (the first load 121 is a light load) and the load current output by the power supply circuit to the second load 122 is 0.2A (the second load 122 is a heavy load), the second voltage V2 output by the power supply circuit is reduced to 9.42V and cannot be stabilized near 18V required for normal operation in cases 2 and 3, so that the third voltage 7.785V obtained by processing the second voltage V2 by the voltage conversion circuit 116 is also smaller than 15V required for normal operation.

In some embodiments, the power supply circuit may increase the load current for the first load 121 by placing a dummy load at the output of the first secondary circuit 133 when the conditions as in the first column of table 1 occur. For example, fig. 4 is a schematic structural diagram of another power supply circuit in the related art, and the power supply circuit shown in fig. 4 further includes a dummy load circuit 123 at the output terminal of the first secondary circuit on the basis of fig. 2. The dummy load circuit 123 may be connected to an output terminal of the first secondary circuit 113 and in parallel with the first load 121. The dummy load circuit 123 may include at least one load resistor, and the resistance of the entire dummy load circuit 123 may be used to provide the load current. When the first secondary circuit 133 outputs the first voltage V1, the dummy load circuit 123 can increase the load current at the output terminal of the first voltage V1, so as to increase the second voltage V2 from 9.42V to about 18V, and further increase the third voltage V3 from 7.785V to about 15V, thereby ensuring the normal and stable operation of the power supply circuit.

However, the dummy load circuit 123 provided in the power supply circuit shown in fig. 4 will continue to operate after being powered on, and even if the output second voltage V2 and the output third voltage V3 are stable, the dummy load circuit 123 will still output a load current, which causes an ineffective energy loss to the power supply circuit, and makes the power supply circuit not meet the energy saving requirement. How to reduce the invalid energy loss of the power supply circuit under the condition of keeping the normal and stable operation of the power supply circuit is a problem to be solved in the field.

Therefore, the application provides a power supply circuit and an electronic device, the dummy load circuit is controlled to be connected or disconnected with the first secondary circuit through the control circuit according to the change of the second voltage, and therefore the invalid energy loss of the power supply circuit is reduced under the condition that the dummy load circuit keeps normal and stable operation of the power supply circuit. The technical solution of the present application will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

Fig. 5 is a schematic structural diagram of an embodiment of a power supply circuit provided in the present application, where the power supply circuit shown in fig. 5 may be applied to the electronic device 10 shown in fig. 1, and the power supply circuit includes: the circuit comprises a first primary side circuit 111, a transformer 112, a first secondary side circuit 113, a second primary side circuit 114, a driving circuit 115, a voltage conversion circuit 116, a feedback circuit 117 and a control circuit 118. Specific implementation manners and operating principles of the first primary circuit 111, the transformer 112, the first secondary circuit 113, the second primary circuit 114, the driving circuit 115, and the voltage conversion circuit 116 may refer to the embodiments in fig. 2 to fig. 3, and are not described again.

In some embodiments, the present application provides a power supply circuit in which the control circuit 118 is disposed between the first voltage V1 and the second voltage V2 output by the power supply circuit, and is connected to the output of the first secondary circuit 113, the dummy load circuit 123 and the output of the second primary circuit 114. The control circuit 118 is configured to detect a second voltage V2 output by the second primary circuit 114 to the voltage conversion circuit 116, and when the second voltage is greater than a preset threshold value Vldo _ in _ min, the control circuit 118 controls the dummy load circuit 123 to be disconnected from the first dummy load circuit 113, and at this time, when the first dummy load circuit 113 outputs a first voltage V1 to the first load 121, the dummy load circuit 123 does not provide a load current; when the second voltage is less than the preset threshold value Vldo _ in _ min, the control circuit 118 controls the dummy load circuit 123 to establish a connection with the first sub-circuit 113, and at this time, the dummy load circuit 123 can provide the load current when the first sub-circuit 113 outputs the first voltage V1 to the first load 121. When the second voltage is equal to the preset threshold value Vldo _ in _ min, the control circuit 118 may control the dummy load circuit 123 to be connected or disconnected with the first secondary circuit 113.

Fig. 6 is a schematic structural diagram of an embodiment of the control circuit provided in the present application, and illustrates a specific implementation manner of the control circuit 118 in fig. 5. The control circuit 118 shown in fig. 6 includes: a detection circuit 1181, an isolation circuit 1182, and a switching circuit 1183. The detection circuit 1181 is connected to the second primary side circuit 114 and is configured to detect a second voltage V2 output by the second primary side circuit 114, the isolation circuit 1182 is configured to isolate the detection circuit 1181 from the switch circuit 1183, the switch circuit 1183 is connected in series with the dummy load circuit 123, and a circuit formed by the series connection is connected in parallel with the first secondary side circuit 113.

Fig. 7 is a schematic circuit structure diagram of an embodiment of a control circuit provided in the present application, which shows a specific implementation manner of the control circuit in fig. 6, as shown in fig. 7:

the detection circuit 1181 includes: the circuit comprises a first resistor R1, a second resistor R2, a third resistor R3 and a first switch Q1. The first end of the first resistor R1 is connected to the end of the second primary circuit 114 outputting the second voltage V2, the second end of the first resistor R1 is connected to the first end of the second resistor R2 and the control end of the first switch Q1, the first end of the third resistor R3 is connected to the first end of the first resistor R1, the second end of the third resistor R3 is connected to the first input end of the isolation circuit 1182, the first end of the first switch Q1 is connected to the second input end of the isolation circuit 1182, and the second end of the first switch Q1 is grounded.

The isolation circuit 1182 includes: and an optical coupler U1. The optical coupler U1 includes a light emitter U1A and a light receiver U1B, a first input end of the light emitter U1A is connected to a second end of the third resistor R3, a second input end of the light emitter U1A is connected to a first end of the first switch Q1, a first output end of the light receiver U1B is connected to the fifth resistor R5, the fourth resistor R4 and the second switch Q2, and a second output end of the light receiver U1B is grounded.

The switching circuit 1183 includes: a fourth resistor R4, a fifth resistor R5 and a second switch Q2. The first end of the fifth resistor R5 is connected to the end of the first secondary circuit 111 outputting the first voltage V1, the second end of the fifth resistor is connected to the second output end of the optocoupler U1, the first end of the fourth resistor R4 and the control end of the second switch Q2, the second end of the fourth resistor R4 is grounded, the first end of the second switch Q2 is connected to the second end of the dummy load resistor R6 in the dummy load circuit 123, the second end of the second switch Q2 is grounded, and the first end of the dummy load resistor R6 is connected to the end of the first secondary circuit 111 outputting the first voltage V1.

In some embodiments, the first switch and the second switch may be a triode, a Metal-Oxide-Semiconductor Field-Effect Transistor (MOS Transistor), an Insulated Gate Bipolar Transistor (IGBT), or the like.

Fig. 8 is a schematic diagram of an operation timing sequence of the power supply circuit provided in the present application, which shows the control circuit shown in fig. 7, and when the control circuit is applied to the power supply circuit shown in fig. 5, the control circuit controls a connection relationship between the dummy load circuit 123 and the first secondary circuit 113 according to the second voltage V2 output by the power supply circuit, and then the schematic diagram of the load current I _ load and the load voltage V _ load of the dummy load resistor R6 in the dummy load circuit 123.

As shown in fig. 8, before t1 and after t2, when the second voltage V2 output by the power supply circuit gradually increases from 0V to 18V, since the second voltage V2 is smaller than the preset threshold Vldo _ in _ min of 18V, it may happen that the second voltage V2 is lower due to the fact that the first load 121 is a light load and the second load 122 is a heavy load in case 1 shown in table 1, and therefore, the control circuit 118 needs to control the dummy load circuit 123 to establish a connection with the first secondary side circuit 113 at this time, and the dummy load circuit 123 provides the load current.

Specifically, when the second voltage V2 is less than 18V, the second voltage V2 is divided by the first resistor R1 and the second resistor R2, the base current Ib _ Q1 generated on the first switch Q1 is less than the on-current of the first switch Q1, and the first switch Q1 operates in an off region and forms an off state. At this time, the light emitting diode U1A in the optocoupler U1 is turned off, and the generated light turns off the phototransistor U1B. The first voltage V1 is divided by the fourth resistor R4 and the fifth resistor R5, the base current Ib _ Q2 generated on the second switch Q2 is larger than the on-state current of the second switch Q2, the second switch Q2 is turned on, and the dummy load resistor R6 is turned on and connected to the output end of the first voltage V1, so that the first voltage V1 forms the load current I _ load on the dummy load resistor R6.

Between t1-t2, when the second voltage V2 output by the power supply circuit is greater than 18V, which may correspond to case 2 and case 3 in table 1, at this time, even if the dummy load circuit 123 does not supply the load current, the second voltage V2 output by the power supply circuit is stabilized around 18V, so the control circuit 118 controls the dummy load circuit 123 to be disconnected from the first sub-side circuit 113, and stops the supply of the load current by the dummy load circuit 123.

Specifically, when the second voltage V2 is greater than 18V, the second voltage V2 is divided by the first resistor R1 and the second resistor R2, the base current Ib _ Q1 generated on the first switch Q1 is greater than the on-current of the first switch Q1, and the first switch Q1 operates in a saturation region and forms an on-state. At this time, the light emitting diode U1A in the optocoupler U1 is turned on, and the generated light turns on the phototransistor U1B. The first voltage V1 is divided by the fourth resistor R4 and the fifth resistor R5, the base current Ib _ Q2 generated on the second switch Q2 is smaller than the on current of the second switch Q2, the second switch Q2 is turned off, and the dummy load resistor R6 is disconnected from the output end of the first voltage V1, so that the first voltage V1 cannot form the load current I _ load on the dummy load resistor R6.

In summary, the power supply circuit provided in the embodiment of the present application can control the dummy load circuit to be connected or disconnected with the first load according to the voltage value of the second voltage V2 output by the second primary side circuit through the control circuit, so that when the first load is a light load, the second load is a heavy load, and the like, and the second voltage is smaller than the preset threshold, the dummy load circuit and the first secondary side circuit are connected to provide a load current for the first load, so that the second voltage V2 and a third voltage V3 subsequently provided for the second load can be kept normal and stable; when the second voltage is greater than the preset threshold value, the connection relation between the dummy load circuit and the first secondary side circuit is disconnected, the invalid energy loss of the dummy load circuit when the load current does not need to be supplied to the first load is reduced, the whole control process is more intelligent, the circuit structure is simple, the invalid energy loss of the power supply circuit is reduced under the condition that the normal and stable work of the power supply circuit is kept, and the power supply circuit and the electronic equipment where the power supply circuit is located are ensured to meet certain energy-saving requirements.

Based on the same concept, the present application also provides an implementation manner of a control circuit, which can be applied to the power supply circuit shown in fig. 5, in this embodiment, the dummy load circuit 123 is set as a variable resistor, and then the control circuit 118 can adjust the resistance value of the variable circuit in the dummy load circuit 123 according to the voltage value of the second voltage V2; alternatively, the dummy load circuit 123 may be a voltage-based adjustable variable resistor, and the control circuit 118 may be configured to obtain the second voltage V2 and output a corresponding voltage to the variable resistor, and the variable resistor adjusts the resistance value according to the received voltage. For example, when the second voltage V2 is detected to be greater than the preset threshold, the control circuit 118 controls the resistance value of the variable resistor to increase to provide a larger load current; when the second voltage V1 is detected to be less than the preset threshold, the control circuit 118 controls the resistance value of the variable resistor to decrease to reduce the ineffective energy loss. The control circuit that this embodiment provided, under the circumstances of guaranteeing that supply circuit normally stable work is realized, can also reduce supply circuit's invalid energy loss to need not to set up too much control devices such as opto-coupler, switch in control circuit, make circuit structure simple, still avoided the function anomaly that these devices appear after damaging, improved control circuit, supply circuit and place electronic equipment's life.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application 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 or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power supply circuit, comprising:

the device comprises a first primary side circuit, a transformer, a first secondary side circuit, a second primary side circuit, a voltage conversion circuit, a dummy load circuit and a control circuit; the first primary side circuit is connected with the first secondary side circuit through the transformer, and the transformer is connected with the voltage conversion circuit through the second primary side circuit;

the input voltage passes through the first primary side circuit, the transformer and the first secondary side circuit, and a first voltage is output to a first load; the input voltage passes through the first primary side circuit, the transformer and the second primary side circuit and outputs a second voltage to the voltage conversion circuit, and the voltage conversion circuit converts the second voltage and outputs a third voltage to a second load;

the control circuit is connected with the second primary side circuit and the dummy load circuit, and the control circuit controls the dummy load circuit to be connected or disconnected with the first secondary side circuit according to the second voltage.

2. The circuit of claim 1,

when the second voltage is larger than a preset threshold value, the control circuit controls the dummy load circuit to be disconnected with the first secondary circuit;

when the second voltage is smaller than the preset threshold value, the control circuit controls the dummy load circuit to be connected with the first secondary circuit;

when the second voltage is equal to the preset threshold, the control circuit controls the dummy load circuit to be disconnected or connected with the first secondary circuit.

3. The circuit of claim 2, wherein the control circuit comprises:

the detection circuit, the isolation circuit and the switch circuit; the detection circuit is connected with the second primary side circuit, the detection circuit is connected with the switch circuit through the isolation circuit, and the switch circuit is connected with the dummy load circuit in series;

the detection circuit is used for controlling the switch-on or switch-off of the switch circuit through the isolation circuit according to a second voltage, so that the dummy load circuit is disconnected or connected with the first secondary side circuit.

4. The circuit of claim 3, wherein the detection circuit comprises:

the circuit comprises a first resistor, a second resistor, a third resistor and a first switch;

the first end of the first resistor is connected with the second primary side circuit and the first end of the third resistor, the second end of the first resistor is connected with the first end of the second resistor and the control end of the first switch, the second end of the third resistor is connected with the isolation circuit, the first end of the first switch is connected with the isolation circuit, and the second end of the first switch is grounded.

5. The circuit of claim 4, wherein the switching circuit comprises:

a fourth resistor, a fifth resistor and a second switch;

the first end of the fifth resistor is connected with the first secondary side circuit, the second end of the fifth resistor is connected with the isolation circuit, the first end of the fourth resistor and the control end of the second switch, the second end of the fourth resistor is grounded, the first end of the second switch is connected with the dummy load circuit, and the second end of the second switch is grounded.

6. The circuit of claim 5, wherein the isolation circuit comprises:

an optical coupler;

the first input end of opto-coupler is connected the second end of third resistance, the second input end of opto-coupler is connected the first end of first switch, the first output end of opto-coupler is connected the second end of fifth resistance the first end of fourth resistance with the control end of second switch, the second output end ground connection of opto-coupler.

7. The circuit according to any one of claims 1-6,

the dummy load circuit includes: at least one dummy load resistor.

8. The circuit according to any one of claims 1-6,

the second primary side circuit also outputs a fourth voltage to the drive circuit of the first primary side circuit.

9. The circuit of claim 1,

and the control circuit controls the resistance value of the dummy load circuit according to the second voltage.

10. An electronic device, characterized in that it comprises a supply circuit according to any one of claims 1-9.