Power supply circuit and power supply device

Abstract

The invention discloses a power supply circuit and power supply equipment, and belongs to the technical field of electronics. The power supply circuit comprises a field effect transistor; the variable resistance circuit is connected with the field effect transistor; the load detection circuit is used for detecting the load voltage of the power supply circuit; the driving circuit is connected with the load detection circuit and the variable resistance circuit; wherein the driving circuit is used for driving the variable resistance circuit to increase the resistance value under the condition that the load voltage is greater than a preset threshold value, and driving the variable resistance circuit to reduce the resistance value under the condition that the load voltage is smaller than the preset threshold value.

Description

Technical Field

[0001] The present application belongs to the field of electronic technology, and specifically relates to a power supply circuit and a power supply device. Background Art

[0002] During the development process of power devices such as chargers, a lot of effort is often spent on optimizing their energy efficiency and EMI (Electromagnetic Interference) to ensure the working effect of the power devices.

[0003] However, currently, there are often defects when optimizing the power circuit in the power supply device. For example, when the energy efficiency of the power circuit is optimized, the electromagnetic interference margin is insufficient, or when the electromagnetic interference of the power circuit is optimized, the energy efficiency is lost.

[0004] In this way, it is difficult to optimize the power supply circuit to take both electromagnetic interference and energy efficiency into consideration, which reduces the reliability of the power supply circuit. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a power supply circuit and a power supply device that can optimize both the electromagnetic interference and energy efficiency of the power supply circuit and improve the reliability of the power supply circuit.

[0006] In a first aspect, an embodiment of the present application provides a power supply circuit, comprising: a field effect transistor; a variable resistance circuit connected to the field effect transistor; a load detection circuit for detecting the load voltage of the power supply circuit; and a drive circuit connected to the load detection circuit and the variable resistance circuit; wherein the drive circuit is used to drive the variable resistance circuit to increase the resistance value when the load voltage is greater than a preset threshold value, and to drive the variable resistance circuit to decrease the resistance value when the load voltage is less than the preset threshold value.

[0007] In a second aspect, an embodiment of the present application provides a power supply device, including: the power supply circuit of the first aspect.

[0008] The power supply circuit provided in the embodiment of the present application includes a field effect tube, a variable resistor circuit, a load detection circuit and a drive circuit. Among them, the variable resistor circuit is connected to the field effect tube, and the drive circuit is connected to the load detection circuit and the variable resistor circuit. Further, the load detection circuit is used to detect the load voltage of the power supply circuit, and the drive circuit is used to drive the variable resistor circuit to increase the resistance value when the load voltage is greater than a preset threshold, and drive the variable resistor circuit to reduce the resistance value when the load voltage is less than the preset threshold. Through the above-mentioned power supply circuit, a variable resistor circuit is set in the power supply circuit as a driving resistor of the field effect tube. When the load voltage of the power supply circuit is large and the electromagnetic interference margin is insufficient, the resistance value of the variable resistor circuit is increased to increase the electromagnetic interference margin; and when the load voltage of the power supply circuit is small and the electromagnetic interference margin is sufficient, the resistance value of the variable resistor circuit is reduced to improve energy efficiency. In this way, it is possible to optimize the electromagnetic interference and energy efficiency of the power supply circuit, thereby improving the reliability of the power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A structural block diagram of a power supply circuit provided in an embodiment of the present application;

[0010] Figure 2 A schematic diagram comparing the power supply circuit provided in the embodiment of the present application with the power supply circuit in the related art;

[0011] Figure 3 A principle block diagram of a power supply circuit provided in an embodiment of the present application;

[0012] Figure 4 One of the partial circuit structure schematic diagrams of the power supply circuit provided in the embodiment of the present application;

[0013] Figure 5 A second schematic diagram of a partial circuit structure of a power supply circuit provided in an embodiment of the present application;

[0014] Figure 6 A third schematic diagram of a partial circuit structure of a power supply circuit provided in an embodiment of the present application;

[0015] Figure 7 is a circuit structure diagram of a power supply circuit in the related art;

[0016] Figure 8 A schematic diagram of the circuit structure of a power supply circuit provided in an embodiment of the present application;

[0017] Fig. 9 This is a structural block diagram of the power supply device provided in an embodiment of the present application.

[0018] Reference numerals:

[0019] 100 power supply circuit, 102 field effect transistor, 104 variable resistance circuit, 106 load detection circuit, 108 drive circuit, 110 first resistor, 112 second resistor, 114 switch, 116 first chip, 118 first pin, 120 first load circuit, 122 second pin, 124 first detection circuit, 126 third resistor, 128 fourth resistor, 130 first amplifier, 132 second load circuit, 134 second chip, 136 optocoupler device, 138 third pin, 140 second detection circuit, 142 fifth resistor, 144 fourth pin, 146 fifth pin, 148 sixth pin, 150 second amplifier, 152 third amplifier, 154 sixth resistor, 156 capacitor element, 158 seventh resistor, 200 power supply device. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0021] The features of the terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0022] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] Combine the following Figure 1-Figure 9 The power supply circuit and the power supply device according to the embodiments of the present application are described in detail.

[0024] like Figure 1 As shown, the embodiment of the present application provides a power supply circuit 100. Figure 1 and Figure 8 As shown, the power supply circuit 100 includes a field effect transistor 102 , a variable resistance circuit 104 , a load detection circuit 106 and a driving circuit 108 .

[0025] Furthermore, the variable resistance circuit 104 is connected to the field effect transistor 102 , and the driving circuit 108 is connected to the load detection circuit 106 and the variable resistance circuit 104 .

[0026] Furthermore, the load detection circuit 106 is used to detect the load voltage of the power supply circuit 100 .

[0027] The power supply circuit 100 can convert high voltage into low voltage, the high voltage is called the primary side, and the low voltage is called the secondary side. On this basis, the load voltage can be obtained by performing primary current detection or secondary current detection on the power supply circuit 100, and no specific limitation is made here.

[0028] Furthermore, the driving circuit 108 is used to drive the variable resistor circuit 104 to increase the resistance value to improve the electromagnetic interference margin of the power circuit 100 when the load voltage is greater than a preset threshold, that is, when the electromagnetic interference margin of the power circuit 100 is insufficient.

[0029] Furthermore, the driving circuit 108 is also used to drive the variable resistor circuit 104 to reduce the resistance value to improve the energy efficiency of the power circuit 100 when the load voltage is less than a preset threshold, that is, when the electromagnetic interference margin of the power circuit 100 is sufficient.

[0030] Among them, the specific value of the above-mentioned preset threshold can be set by those skilled in the art according to actual conditions, and no specific limitation is made here.

[0031] It is understandable that if Figure 7 As shown in the figure, one of the reasons for the deterioration of EMI in the traditional power supply circuit is that the semiconductor field effect transistor Q1 is turned on and off quickly. This fast change in voltage and current will cause the EMI of the power supply circuit to deteriorate. In order to slow down the rapid change of voltage and current, such as Figure 7 As shown in Figure 1, the usual measure is to add a fixed driving resistor R to slow down the rapid changes in voltage and current. However, although this can improve EMI, it will also reduce energy efficiency.

[0032] Therefore, in the power supply circuit 100 provided in the embodiment of the present application, Figure 2 As shown, the fixed driving resistor R in the conventional power supply circuit is set as a variable resistor circuit 104 as the driving resistor of the field effect transistor 102, and the resistance value of the variable resistor circuit 104 changes depending on the load voltage of the power supply circuit 100. Specifically, as Figure 3As shown, in the power supply circuit 100 provided in the embodiment of the present application, the load detection circuit 106 accurately detects the load voltage of the power supply circuit 100, and outputs a control signal to the variable resistance circuit 104 according to the detection result, so as to drive the resistance value of the variable resistance circuit 104 to change through the control signal. Specifically, when the load detection circuit 106 detects that the load voltage of the power supply circuit 100 is greater than the preset threshold, that is, when the power supply circuit 100 works in a large current and heavy load scenario, the electromagnetic interference margin of the power supply circuit 100 is insufficient. At this time, the resistance value of the variable resistance circuit 104 is increased to slow down the rapid change of the voltage and current of the field effect tube 102, and improve the electromagnetic interference margin of the power supply circuit 100; and when the load detection circuit 106 detects that the load voltage of the power supply circuit 100 is less than the preset threshold, that is, when the power supply circuit 100 works in a small current and light load scenario, the electromagnetic interference margin of the power supply circuit 100 is sufficient. At this time, the resistance value of the variable resistance circuit 104 is reduced to reduce the loss of the switch 114 of the power supply circuit 100 and improve the energy efficiency of the power supply circuit 100. When the load detection circuit 106 detects that the load voltage of the power supply circuit 100 is equal to the preset threshold, the resistance value of the variable resistance circuit 104 remains unchanged. In this way, the electromagnetic interference and energy efficiency of the power supply circuit 100 can be balanced, and the electromagnetic interference and energy efficiency of the power supply circuit 100 can be optimized, thereby improving the reliability of the power supply circuit 100.

[0033] According to the power supply circuit 100 of the embodiment of the present application, it includes a field effect tube 102, a variable resistance circuit 104, a load detection circuit 106 and a driving circuit 108. Among them, the variable resistance circuit 104 is connected to the field effect tube 102, and the driving circuit 108 is connected to the load detection circuit 106 and the variable resistance circuit 104. Further, the load detection circuit 106 is used to detect the load voltage of the power supply circuit 100, and the driving circuit 108 is used to drive the variable resistance circuit 104 to increase the resistance value when the load voltage is greater than the preset threshold, and drive the variable resistance circuit 104 to reduce the resistance value when the load voltage is less than the preset threshold. Through the above-mentioned power supply circuit 100, the variable resistance circuit 104 is set in the power supply circuit 100 as the driving resistance of the field effect tube 102. When the load voltage of the power supply circuit 100 is large and the electromagnetic interference margin is insufficient, the resistance value of the variable resistance circuit 104 is increased to improve the electromagnetic interference margin; and when the load voltage of the power supply circuit 100 is small and the electromagnetic interference margin is sufficient, the resistance value of the variable resistance circuit 104 is reduced to improve energy efficiency. In this way, the electromagnetic interference and energy efficiency of the power supply circuit 100 can be optimized, thereby improving the reliability of the power supply circuit 100.

[0034] According to some embodiments of the present application, optionally, Figure 4As shown, the variable resistance circuit 104 includes a first resistor 110 , a second resistor 112 , and a switch 114 .

[0035] The first resistor 110 is connected to the field effect transistor 102 and the driving circuit 108 , the second resistor 112 is connected to the field effect transistor 102 and the switch 114 , and the switch 114 is also connected to the driving circuit 108 .

[0036] Furthermore, the driving circuit 108 is used to drive the switch 114 to disconnect when the load voltage of the power supply circuit 100 is greater than a preset threshold, that is, when the power supply circuit 100 operates in a high current heavy load scenario, that is, when the electromagnetic interference margin of the power supply circuit 100 is insufficient, so as to disconnect the second resistor 112, thereby increasing the resistance value of the variable resistor circuit 104, so as to slow down the rapid changes in the voltage and current of the field effect tube 102 and improve the electromagnetic interference margin of the power supply circuit 100.

[0037] Furthermore, the driving circuit 108 is also used to drive the switch 114 to close when the load voltage of the power supply circuit 100 is less than a preset threshold, that is, when the power supply circuit 100 operates in a small current and light load scenario, that is, when the electromagnetic interference margin of the power supply circuit 100 is sufficient, so that the first resistor 110 and the second resistor 112 are connected in parallel, thereby reducing the resistance value of the variable resistor circuit 104, thereby reducing the switch 114 loss of the power supply circuit 100 and improving the energy efficiency of the power supply circuit 100.

[0038] In this way, based on the load voltage of the power supply circuit 100, the switch 114 is controlled to be opened or closed, thereby controlling the resistance value change of the variable resistor circuit 104, which can optimize the electromagnetic interference and energy efficiency of the power supply circuit 100 and improve the reliability of the power supply circuit 100.

[0039] According to the power supply circuit 100 of the embodiment of the present application, the variable resistance circuit 104 includes a first resistor 110, a second resistor 112 and a switch 114. Among them, the first resistor 110 is connected to the field effect tube 102 and the driving circuit 108; the second resistor 112 is connected to the field effect tube 102; the switch 114 is connected to the second resistor 112 and the driving circuit 108. Further, the driving circuit 108 is used to drive the switch 114 to open when the load voltage is greater than a preset threshold, and to drive the switch 114 to close when the load voltage is less than the preset threshold. In this way, based on the load voltage of the power supply circuit 100, the switch 114 is controlled to open or close, thereby controlling the change in the resistance value of the variable resistance circuit 104, which can take into account the optimization of the electromagnetic interference and energy efficiency of the power supply circuit 100, and improve the reliability of the power supply circuit 100.

[0040] According to some embodiments of the present application, optionally, Figure 8As shown, the driving circuit 108 includes a first chip 116 .

[0041] The first pin 118 of the first chip 116 is connected to the switch 114 in the variable resistance circuit 104 .

[0042] During the operation of the power supply circuit 100, the first chip 116 can receive the output value of the load detection circuit 106, and drive the switch 114 to open or close according to the output value of the load detection circuit 106, thereby driving the resistance value of the resistance circuit to change, so as to increase the resistance value of the variable resistance circuit 104 to improve the electromagnetic interference margin when the load voltage of the power supply circuit 100 is large and the electromagnetic interference margin is insufficient, and to reduce the resistance value of the variable resistance circuit 104 to improve energy efficiency when the load voltage of the power supply circuit 100 is small and the electromagnetic interference margin is sufficient.

[0043] According to the power supply circuit 100 of the embodiment of the present application, the driving circuit 108 further includes a first chip 116. Among them, the first pin 118 of the first chip 116 is connected to the switch 114. In this way, based on the load voltage of the power supply circuit 100, the switch 114 is driven to open or close by the first chip 116, so that the resistance value of the driving resistance circuit changes, and the automatic adjustment of the driving resistance of the field effect tube 102 is realized.

[0044] According to some embodiments of the present application, optionally, Figure 8 As shown, the power supply circuit 100 further includes a first load circuit 120 .

[0045] The first load circuit 120 is connected to both the field effect transistor 102 and the second pin 122 of the first chip 116 .

[0046] Further, the load detection circuit 106 includes a first detection circuit 124 .

[0047] The first detection circuit 124 is disposed in the first chip 116 .

[0048] Furthermore, an output end of the first detection circuit 124 is connected to the first pin 118 of the first chip 116 , and an input end of the first detection circuit 124 is connected to the second pin 122 of the first chip 116 .

[0049] Further, the first detection circuit 124 detects the primary load voltage of the power circuit 100 based on the primary current, and the primary load voltage is the input load voltage of the power circuit 100. Specifically, the first detection circuit 124 is used to detect the load voltage of the first load circuit 120.

[0050] Further, when the load voltage of the first load circuit 120 is greater than a preset threshold, the first detection circuit 124 outputs a low level, and when the load voltage of the first load circuit 120 is less than the preset threshold, the first detection circuit 124 outputs a high level.

[0051] Furthermore, during the operation of the power supply circuit 100, the first chip 116 can receive the output value of the first detection circuit 124, and when the first detection circuit 124 outputs a low level, drive the switch 114 to open to increase the resistance value of the variable resistance circuit 104, thereby improving the electromagnetic interference margin of the power supply circuit 100; and when the first detection circuit 124 outputs a high level, drive the switch 114 to close to reduce the resistance value of the variable resistance circuit 104, thereby improving the energy efficiency of the power supply circuit 100.

[0052] According to the power supply circuit 100 of the embodiment of the present application, the power supply circuit 100 further includes a first load circuit 120, and the load detection circuit 106 includes a first detection circuit 124. The first load circuit 120 is connected to the field effect tube 102 and the second pin 122 of the first chip 116; the first detection circuit 124 is arranged in the first chip 116, and the first detection circuit 124 is connected to both the first pin 118 and the second pin 122. Further, the first detection circuit 124 is used to detect the load voltage of the first load circuit 120, and output a low level when the load voltage of the first load circuit 120 is greater than a preset threshold, and output a high level when the load voltage of the first load circuit 120 is less than the preset threshold; the first chip 116 is used to drive the switch 114 to open when the first detection circuit 124 outputs a low level, and drive the switch 114 to close when the first detection circuit 124 outputs a high level. In this way, based on the primary load voltage of the power supply circuit 100, the switch 114 is controlled to be opened or closed, thereby controlling the change in the resistance value of the variable resistor circuit 104, which can optimize the electromagnetic interference and energy efficiency of the power supply circuit 100 and improve the reliability of the power supply circuit 100.

[0053] According to some embodiments of the present application, optionally, Figure 8 As shown, the first load circuit 120 includes a plurality of third resistors 126 and a fourth resistor 128 .

[0054] A first end of each third resistor 126 is connected to the field effect transistor 102 , and a second end of each third resistor 126 is grounded.

[0055] Further, a first end of the fourth resistor 128 is connected to a first end of the third resistor 126 , and a second end of the fourth resistor 128 is connected to the second pin 122 of the first chip 116 via a CS terminal.

[0056] Furthermore, if Figure 5 As shown, the first detection circuit 124 includes a first amplifier 130 .

[0057] The negative input terminal of the first amplifier 130 is connected to the second end of the fourth resistor 128 through the second pin 122 , the positive input terminal of the first amplifier 130 inputs the first reference voltage as a preset threshold, and the output terminal of the first amplifier 130 is connected to the switch 114 in the variable resistor circuit 104 .

[0058] During the operation of the power supply circuit 100, Figure 5 As shown, the input current I in The input current I flows to GND (ground terminal) through the fourth resistor 128. in The larger the voltage difference V on the fourth resistor 128 is, the o1 The larger the voltage V is, the larger the load voltage of the first load circuit 120 is. o1 Greater than the first reference voltage V ref1 , that is, when the load voltage of the first load circuit 120 is greater than the first reference voltage V ref1 In the case of o2 The voltage level is low to drive the switch 114 to disconnect, thereby disconnecting the second resistor 112 and increasing the resistance value of the variable resistor circuit 104 to slow down the rapid change of the voltage and current of the field effect tube 102 and improve the electromagnetic interference margin of the power supply circuit 100.

[0059] Furthermore, the input current I in The smaller the voltage difference V on the fourth resistor 128 is, the o1 The smaller the voltage V is, the smaller the load voltage of the first load circuit 120 is. o1 Less than the first reference voltage V ref1 , that is, when the load voltage of the first load circuit 120 is less than the first reference voltage V ref1 In the case of o2 is high level to drive the switch 114 to close, so that the first resistor 110 and the second resistor 112 are connected in parallel, reducing the resistance value of the variable resistor circuit 104, thereby reducing the switch 114 loss of the power circuit 100 and improving the energy efficiency of the power circuit 100.

[0060] According to the power supply circuit 100 of the embodiment of the present application, the first load circuit 120 includes a plurality of third resistors 126 and a fourth resistor 128, and the first detection circuit 124 includes a first amplifier 130. The first end of each third resistor 126 is connected to the field effect transistor 102, and the second end of each third resistor 126 is grounded; the first end of the fourth resistor 128 is connected to the first end of the third resistor 126; the negative input end of the first amplifier 130 is connected to the second end of the fourth resistor 128, the positive input end of the first amplifier 130 inputs the first reference voltage as a preset threshold, and the output end of the first amplifier 130 is connected to the switch 114. Further, when the load voltage of the first load circuit 120 is greater than the first reference voltage, the first amplifier 130 outputs a low level, and when the load voltage of the first load circuit 120 is less than the first reference voltage, the first amplifier 130 outputs a high level. In this way, based on the primary load voltage of the power supply circuit 100, the switch 114 is controlled to be opened or closed, thereby controlling the change in the resistance value of the variable resistor circuit 104, which can optimize the electromagnetic interference and energy efficiency of the power supply circuit 100 and improve the reliability of the power supply circuit 100.

[0061] According to some embodiments of the present application, optionally, Figure 8 As shown, the power supply circuit 100 further includes a second load circuit 132 , a second chip 134 and an optocoupler device 136 .

[0062] Wherein, the second chip 134 is connected to the second load circuit 132;

[0063] Furthermore, the first end of the optocoupler 136 is connected to the third pin 138 of the first chip 116, the second end of the optocoupler 136 is connected to the second chip through the OPTO terminal, the third end of the optocoupler 136 is connected to the third pin 138 of the first chip 116 through the COMP terminal, and the fourth end of the optocoupler 136 is grounded.

[0064] Further, the load detection circuit 106 includes a second detection circuit 140 .

[0065] The second detection circuit 140 is disposed in the second chip 134 .

[0066] Further, the second detection circuit 140 detects the secondary load voltage of the power circuit 100 based on the secondary current, and the secondary load voltage is the output load voltage of the power circuit 100. Specifically, the second detection circuit 140 is used to detect the load voltage of the second load circuit 132.

[0067] Further, when the load voltage of the second load circuit 132 is greater than a preset threshold, the second detection circuit 140 outputs a low level, and when the load voltage of the second load circuit 132 is less than the preset threshold, the second detection circuit 140 outputs a high level.

[0068] Furthermore, during the operation of the power supply circuit 100, the second chip 134 can receive the output value of the second detection circuit 140, and transmit the output value of the second detection circuit 140 to the optocoupler 136, and then transmit the output value of the second detection circuit 140 to the first chip 116 through the optocoupler 136. On this basis, when the second detection circuit 140 outputs a low level, the first chip 116 drives the switch 114 to open to increase the resistance value of the variable resistance circuit 104, thereby improving the electromagnetic interference margin of the power supply circuit 100; and when the second detection circuit 140 outputs a high level, the first chip 116 drives the switch 114 to close to reduce the resistance value of the variable resistance circuit 104, thereby improving the energy efficiency of the power supply circuit 100.

[0069] According to the power supply circuit 100 of the embodiment of the present application, the power supply circuit 100 further includes a second load circuit 132, a second chip 134 and an optocoupler device 136, and the load detection circuit 106 includes a second detection circuit 140. The second chip 134 is connected to the second load circuit 132; the optocoupler device 136 is connected to both the third pin 138 of the first chip 116 and the second chip 134; the second detection circuit 140 is arranged in the second chip 134. Further, the second detection circuit 140 is used to detect the load voltage of the second load circuit 132, and output a low level when the load voltage of the second load circuit 132 is greater than a preset threshold, and output a high level when the load voltage of the second load circuit 132 is less than the preset threshold; the first chip 116 is used to drive the switch 114 to open when the second detection circuit 140 outputs a low level, and drive the switch 114 to close when the second detection circuit 140 outputs a high level. In this way, based on the secondary load voltage of the power supply circuit 100, the switch 114 is controlled to be opened or closed, thereby controlling the change in the resistance value of the variable resistor circuit 104, which can optimize the electromagnetic interference and energy efficiency of the power supply circuit 100 and improve the reliability of the power supply circuit 100.

[0070] According to some embodiments of the present application, optionally, Figure 8 As shown, the second load circuit 132 includes a fifth resistor 142 , and the second chip 134 includes a fourth pin 144 , a fifth pin 146 , and a sixth pin 148 .

[0071] The first end of the fifth resistor 142 is connected to the fourth pin 144 , and the second end of the fifth resistor 142 is connected to the fifth pin 146 .

[0072] Further, the sixth pin 148 is connected to the optocoupler device 136 .

[0073] Furthermore, the fourth pin 144 , the fifth pin 146 and the sixth pin 148 of the second chip 134 are all connected to the second detection circuit 140 .

[0074] During the operation of the power supply circuit 100, the second detection circuit 140 can sample and detect the load voltage of the second load circuit 132 through the fourth pin 144 and the fifth pin 146 of the second chip 134, and the second chip 134 can receive the output value of the second detection circuit 140 through the sixth pin 148, and transmit the output value of the second detection circuit 140 to the optocoupler device 136 through the sixth pin 148, so as to transmit the output value of the second detection circuit 140 to the first chip 116 through the optocoupler device 136.

[0075] According to the power supply circuit 100 of the embodiment of the present application, the second load circuit 132 includes a fifth resistor 142, and the second chip 134 includes a fourth pin 144, a fifth pin 146, and a sixth pin 148. Among them, the fourth pin 144 is connected to the first end of the fifth resistor 142; the fifth pin 146 is connected to the second end of the fifth resistor 142; and the sixth pin 148 is connected to the optocoupler device 136. In this way, the detection result of the secondary side load voltage is transmitted to the first chip 116 by means of the second chip 134 and the optocoupler device 136, so as to control the resistance value change of the variable resistor circuit 104 based on the level of the secondary side load voltage of the power supply circuit 100, thereby optimizing the electromagnetic interference and energy efficiency of the power supply circuit 100.

[0076] According to some embodiments of the present application, optionally, Figure 6 As shown, the second detection circuit 140 includes a second amplifier 150 and a third amplifier 152 .

[0077] Among them, the positive input terminal of the second amplifier 150 is connected to the first end of the fifth resistor 142 through the fourth pin 144 of the second chip 134, the negative input terminal of the second amplifier 150 is connected to the second end of the fifth resistor 142 through the fifth pin 146 of the second chip 134, and the output terminal of the second amplifier 150 is connected to the negative input terminal of the third amplifier 152.

[0078] Furthermore, the second reference voltage is input to the positive input terminal of the third amplifier 152 as a preset threshold, and the output terminal of the third amplifier 152 is connected to the sixth pin 148 of the second chip 134 .

[0079] During the operation of the power supply circuit 100, Figure 6 As shown, the output current I of the power supply circuit 100 outFlows through the fifth resistor 142 from GND2 (ground terminal 2) to GND1 (ground terminal 1), and the output current I out The larger the voltage difference across the fifth resistor 142 is, the output value V of the second amplifier 150 is o3 The larger the load voltage of the second load circuit 132 is, the larger the load voltage of the second load circuit 132 is. o3 Greater than the second reference voltage V ref2 , that is, when the load voltage of the second load circuit 132 is greater than the second reference voltage V ref2 In the case of o4 The voltage level is low to drive the switch 114 to disconnect, thereby disconnecting the second resistor 112 and increasing the resistance value of the variable resistor circuit 104 to slow down the rapid change of the voltage and current of the field effect tube 102 and improve the electromagnetic interference margin of the power supply circuit 100.

[0080] Furthermore, the output current I out The smaller the voltage difference across the fifth resistor 142 is, the output value V of the second amplifier 150 is o3 The smaller the load voltage of the second load circuit 132 is, the smaller the load voltage of the second load circuit 132 is. o3 is less than the second reference voltage V ref2 , that is, when the load voltage of the second load circuit 132 is less than the second reference voltage V ref2 In the case of o4 is high level to drive the switch 114 to close, so that the first resistor 110 and the second resistor 112 are connected in parallel, reducing the resistance value of the variable resistor circuit 104, thereby reducing the switch 114 loss of the power circuit 100 and improving the energy efficiency of the power circuit 100.

[0081] According to the power supply circuit 100 of the embodiment of the present application, the second detection circuit 140 includes a second amplifier 150 and a third amplifier 152. Among them, the positive input terminal of the second amplifier 150 is connected to the fourth pin 144, and the negative input terminal of the second amplifier 150 is connected to the fifth pin 146; the negative input terminal of the third amplifier 152 is connected to the output terminal of the second amplifier 150, the positive input terminal of the third amplifier 152 inputs the second reference voltage as a preset threshold, and the output terminal of the third amplifier 152 is connected to the sixth pin 148. Further, when the load voltage of the second load circuit 132 is greater than the second reference voltage, the third amplifier 152 outputs a low level, and when the load voltage of the second load circuit 132 is less than the second reference voltage, the third amplifier 152 outputs a high level. In this way, based on the high or low load voltage of the secondary side of the power supply circuit 100, the switch 114 is controlled to be opened or closed, thereby controlling the change in the resistance value of the variable resistor circuit 104, which can take into account the optimization of the electromagnetic interference and energy efficiency of the power supply circuit 100, and improve the reliability of the power supply circuit 100.

[0082] According to some embodiments of the present application, optionally, Figure 8 As shown, the power circuit 100 further includes a sixth resistor 154 , a capacitor 156 and a seventh resistor 158 .

[0083] The first end of the sixth resistor 154 is connected to the sixth pin 148 , and the second end of the sixth resistor 154 is connected to the first end of the capacitor 156 .

[0084] Furthermore, a second end of the capacitor 156 is connected to the optocoupler 136 .

[0085] Furthermore, the seventh resistor 158 is connected in parallel with the capacitor 156 .

[0086] During the operation of the power supply circuit 100, the seventh resistor 158 and the capacitor element 156 can form a filtering circuit. When the second chip 134 transmits the output value of the second detection circuit 140 to the optocoupler device 136, the interference signal in the circuit is filtered out with the help of the filtering effect of the filtering circuit. While ensuring the normal operation of the circuit, the accuracy of the first chip 116 driving the variable resistor circuit 104 to adjust the resistance value is improved.

[0087] According to the power supply circuit 100 of the embodiment of the present application, the power supply circuit 100 also includes a sixth resistor 154, a capacitor 156 and a seventh resistor 158. Among them, the first end of the sixth resistor 154 is connected to the sixth pin 148; the first end of the capacitor 156 is connected to the second end of the sixth resistor 154, and the second end of the capacitor 156 is connected to the optocoupler 136; the seventh resistor 158 is connected in parallel with the capacitor 156. In this way, in the process of the second chip 134 transmitting the output value of the second detection circuit 140 to the optocoupler 136, the interference signal in the circuit can be filtered out, and while ensuring the normal operation of the circuit, the accuracy of the first chip 116 driving the variable resistor circuit 104 to adjust the resistance value is improved.

[0088] According to some embodiments of the present application, optionally, Fig. 9 As shown, the embodiment of the present application further provides a power supply device 200. The power supply device 200 includes the power supply circuit 100 in any of the above embodiments. The power supply device 200 provided in the embodiment of the present application includes the power supply circuit 100 in any of the above embodiments, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0089] In actual application, the power supply device 200 includes but is not limited to: charger, DC power supply, AC power supply, switching power supply, inverter power supply, UPS (Uninterruptible Power Supply) power supply, linear power supply, inverter and mobile power supply and other products, without specific restrictions here.

[0090] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0091] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A power supply circuit, characterized in that: include: Field effect transistor; A variable resistance circuit connected to the field effect tube; A load detection circuit, used for detecting the load voltage of the power supply circuit; A driving circuit connected to the load detection circuit and the variable resistance circuit; The driving circuit is used to drive the variable resistor circuit to increase resistance when the load voltage is greater than a preset threshold, and to drive the variable resistor circuit to decrease resistance when the load voltage is less than the preset threshold.

2. The power supply circuit according to claim 1, characterized in that: The variable resistance circuit comprises: A first resistor connected to the field effect transistor and the driving circuit; A second resistor connected to the field effect transistor; a switch connected to the second resistor and the driving circuit; The driving circuit is used to drive the switch to open when the load voltage is greater than the preset threshold, and to drive the switch to close when the load voltage is less than the preset threshold.

3. The power supply circuit according to claim 2, characterized in that: The driving circuit comprises: A first chip, wherein a first pin of the first chip is connected to the switch.

4. The power supply circuit according to claim 3, characterized in that: The power supply circuit also includes: A first load circuit connected to the field effect transistor and the second pin of the first chip; The load detection circuit comprises: A first detection circuit is arranged in the first chip, and the first detection circuit is connected to both the first pin and the second pin; Wherein, the first detection circuit is used to detect the load voltage of the first load circuit, and output a low level when the load voltage of the first load circuit is greater than the preset threshold, and output a high level when the load voltage of the first load circuit is less than the preset threshold; The first chip is used to drive the switch to open when the first detection circuit outputs a low level, and to drive the switch to close when the first detection circuit outputs a high level.

5. The power supply circuit according to claim 4, characterized in that: The first load circuit comprises: A plurality of third resistors, wherein a first end of each of the third resistors is connected to the field effect transistor, and a second end of each of the third resistors is grounded; a fourth resistor, a first end of the fourth resistor being connected to the first end of the third resistor; The first detection circuit comprises: a first amplifier, wherein a negative input terminal of the first amplifier is connected to the second end of the fourth resistor, a positive input terminal of the first amplifier inputs a first reference voltage as the preset threshold, and an output terminal of the first amplifier is connected to the switch; When the load voltage of the first load circuit is greater than the first reference voltage, the first amplifier outputs a low level, and when the load voltage of the first load circuit is less than the first reference voltage, the first amplifier outputs a high level.

6. The power supply circuit according to claim 3, characterized in that: The power supply circuit also includes: a second load circuit; A second chip connected to the second load circuit; an optical coupler device, connected to the third pin of the first chip and the second chip; The load detection circuit comprises: A second detection circuit is arranged in the second chip; Wherein, the second detection circuit is used to detect the load voltage of the second load circuit, and output a low level when the load voltage of the second load circuit is greater than the preset threshold, and output a high level when the load voltage of the second load circuit is less than the preset threshold; The first chip is used to drive the switch to open when the second detection circuit outputs a low level, and to drive the switch to close when the second detection circuit outputs a high level.

7. The power supply circuit according to claim 6, characterized in that: The second load circuit comprises: a fifth resistor; The second chip comprises: A fourth pin connected to the first end of the fifth resistor; A fifth pin connected to the second end of the fifth resistor; The sixth pin is connected to the optocoupler device.

8. The power supply circuit according to claim 7, characterized in that: The second detection circuit comprises: a second amplifier, wherein a positive input terminal of the second amplifier is connected to the fourth pin, and a negative input terminal of the second amplifier is connected to the fifth pin; a third amplifier, wherein a negative input terminal of the third amplifier is connected to an output terminal of the second amplifier, a second reference voltage is input to a positive input terminal of the third amplifier as the preset threshold, and an output terminal of the third amplifier is connected to the sixth pin; When the load voltage of the second load circuit is greater than the second reference voltage, the third amplifier outputs a low level, and when the load voltage of the second load circuit is less than the second reference voltage, the third amplifier outputs a high level.

9. The power supply circuit according to claim 7, characterized in that: The power supply circuit also includes: a sixth resistor, a first end of the sixth resistor being connected to the sixth pin; A capacitor element, wherein a first end of the capacitor element is connected to a second end of the sixth resistor, and a second end of the capacitor element is connected to the optocoupler device; A seventh resistor is connected in parallel with the capacitor element.

10. A power supply device, characterized in that: include: A power supply circuit as claimed in any one of claims 1 to 9.

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