Control circuit for adjusting output voltage of switching power supply

Abstract

The utility model discloses a control circuit for adjusting the output voltage of a switching power supply. The control circuit comprises an operational amplifier circuit, a photoelectric isolation circuit, an operational control circuit and a driving control circuit, the operational amplifier circuit is connected with the optoelectronic isolation circuit which is connected with the operational control circuit, and the operational control circuit is connected with the drive control circuit. The operational amplification circuit comprises a first adjustable gain circuit and an operational amplification input circuit, the operational control circuit comprises a second adjustable gain circuit and an operational control output circuit, and the driving control circuit comprises a driving network circuit and a driving feedback circuit; an output port of the control circuit is connected with a feedback sampling resistor of the switching power supply. By adjusting the bias voltage value, the gain multiple, the voltage division ratio, the resistance ratio and the driving feedback variable, the high-linearity voltage signal can control the output voltage of the switching power supply, the circuit structure is simple, the control is convenient, and the control efficiency and the reliability of the output voltage of the switching power supply can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit output voltage control, in particular to a control circuit for adjusting the output voltage of a switching power supply. Background Art

[0002] Industrial power supply refers to switching power supplies and various special power supplies used in industrial production equipment. Most existing industrial power supplies use power electronics technology to convert input electrical energy into electrical energy suitable for use in various industrial equipment. Switching power supply is one specific form of this. The vast majority of industrial voltages are supplied by adjustable DC sources to achieve adjustable power.

[0003] There are plenty of big-brand products with mature technical solutions on the current market, and the reliability and stability of switching power supplies have been tested in long-term application and market. The quality of such switching power supplies is relatively guaranteed. If such products are used for secondary development, it will bring great convenience. However, most of these switching power supplies have fixed output voltages. If they are used in scenarios that require continuous power adjustment, it cannot be achieved on the original basis. Utility Model Content

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art. The present invention provides a control circuit for adjusting the output voltage of a switching power supply. The circuit can achieve high linearity voltage signal control of the output voltage of the switching power supply by adjusting the bias voltage value, gain multiple, voltage divider ratio, resistance ratio and drive feedback variable. The circuit has a simple circuit structure and is easy to control, which is conducive to improving the control efficiency and reliability of the output voltage of the switching power supply.

[0005] The utility model provides a control circuit for adjusting the output voltage of a switching power supply, the control circuit comprising an operational amplifier circuit, a photoelectric isolation circuit, an operational control circuit and a drive control circuit;

[0006] The input end of the operational amplifier circuit is the input port of the control circuit, the output end of the operational amplifier circuit is connected to the input end of the photoelectric isolation circuit, the output end of the photoelectric isolation circuit is connected to the input end of the operational control circuit, the output end of the operational control circuit is connected to the input end of the drive control circuit, and the output end of the drive control circuit is the output port of the control circuit;

[0007] The operational amplifier circuit includes a first adjustable gain circuit and an operational amplifier input circuit, the operational control circuit includes a second adjustable gain circuit and an operational control output circuit, and the drive control circuit includes a drive network circuit and a drive feedback circuit;

[0008] The output port of the control circuit is connected to the feedback sampling resistor of the switching power supply.

[0009] Furthermore, the first adjustable gain circuit includes an operational amplifier OP1, a resistor R1, a resistor R2, a resistor R3, and a capacitor C1, wherein the inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R1, the first end of the resistor R2, and the first end of the capacitor C1, the output terminal of the operational amplifier OP1 is connected to the second ends of the resistor R1 and the capacitor C1, and the non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R3;

[0010] The operational amplifier input circuit includes an operational amplifier OP2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a capacitor C2. The inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R4, the first end of the resistor R5, and the first end of the resistor R6. The second end of the resistor R4 and the second end of the resistor R5 are grounded. The output terminal of the operational amplifier OP2 is connected to the second end of the resistor R6 and the second end of the resistor R2. The non-inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R7, the first end of the resistor R8, and the first end of the resistor R9. The second end of the resistor R7 is connected to the operational amplifier input voltage port VSET and the first end of the capacitor C2. The second end of the capacitor C2 is grounded. The second end of the resistor R8 is connected to the operational amplifier bias voltage port VBIAS. The second end of the resistor R9 is grounded.

[0011] Furthermore, the operational amplifier circuit also includes an operational amplifier output circuit, which includes a resistor R10, a resistor R11, and a capacitor C3. The first end of the resistor R10 is connected to the second end of the resistor R3, the second end of the resistor R10 is connected to the input first power supply port VDD1, the first end of the resistor R11 is connected to the output end of the operational amplifier OP1, the second end of the resistor R11 is connected to the first end of the capacitor C3, and the first end of the capacitor C3 is grounded.

[0012] Furthermore, the optoelectronic isolation circuit includes a DC power supply isolation circuit, an optoelectronic isolation input and output circuit, and an optoelectronic isolation feedback circuit. The DC power supply isolation circuit is a neighboring power supply circuit, including two branch circuits, one branch circuit connected to the first power supply port VDD1, and the other branch circuit connected to the second power supply port VDD2. The optoelectronic isolation input and output circuit includes a first optoelectronic isolator OC1, and the first optoelectronic isolator OC1 includes a first light-emitting diode D1 and a first phototransistor Q1. The optoelectronic isolation feedback circuit includes a second optoelectronic isolator OC2, and the second optoelectronic isolator OC2 includes a second light-emitting diode D2 and a second phototransistor Q2. The anode of the first light-emitting diode D1 and the collector of the second phototransistor Q2 are connected to the output end of the operational amplifier circuit, the cathode of the first light-emitting diode D1 is connected to the anode of the second light-emitting diode D2, the collector of the first phototransistor Q1 is connected to the input end of the operational control circuit, and the cathode of the second light-emitting diode D2, the emitter of the first phototransistor Q1, and the emitter of the second phototransistor Q2 are grounded.

[0013] Furthermore, the second adjustable gain circuit includes an operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, and a capacitor C4, wherein the inverting input terminal of the operational amplifier OP3 is connected to the first end of the resistor R12, the first end of the resistor R13, and the first end of the capacitor C4, the output terminal of the operational amplifier OP3 is connected to the second ends of the resistor R12 and the capacitor C4, and the non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R14;

[0014] The operational control output circuit includes an operational amplifier OP4, a resistor R15, a resistor R16, and a capacitor C5. The inverting input terminal and the output terminal of the operational amplifier OP4 are connected, and are also connected to the first end of the resistor R15 and the first end of the capacitor C5. The second end of the resistor R15 and the first end of the resistor R16 are connected to the second end of the resistor R14. The second end of the capacitor C5 and the second end of the resistor R16 are grounded.

[0015] Furthermore, the operation control circuit also includes an operation control input circuit and an operation control feedback circuit, the operation control input circuit includes a resistor R17 and a resistor R18, a first end of the resistor R17 is connected to the second power supply port VDD2, a second end of the resistor R17 and a first end of the resistor R18 are connected to the output end of the photoelectric isolation circuit, and a second end of the resistor R18 is connected to the non-inverting input end of the operational amplifier OP4;

[0016] The operation control feedback circuit includes a capacitor C6 , a first end of the capacitor C6 is connected to the second end of the resistor R13 , and a second end of the capacitor C6 is grounded.

[0017] Furthermore, the driving network circuit includes a resistor R19, a resistor R20, and a capacitor C7, wherein a first end of the resistor R19 is connected to the output end of the operation control circuit, a second end of the resistor R19 is connected to a first end of the resistor R20 and a first end of the capacitor C7, and a second end of the resistor R20 and a second end of the capacitor C7 are grounded;

[0018] The driving feedback circuit includes a resistor R21 , and a first end of the resistor R21 is grounded.

[0019] Furthermore, the drive control circuit also includes a drive output circuit, which includes a transistor Q3 and a resistor R22. The base of the transistor Q3 is connected to the second end of the resistor R19, the first end of the resistor R20, and the first end of the capacitor C7. The emitter of the transistor Q3 is connected to the second end of the resistor R21, and the collector of the transistor Q3 is connected to the first end of the resistor R22.

[0020] Furthermore, the emitter of the transistor Q3 and the second end of the resistor R21 are connected to the first end of the capacitor C6 and the second end of the resistor R13.

[0021] Furthermore, the second end of the resistor R22 is connected to the feedback sampling resistor RH of the switching power supply, and the first end of the resistor R21 is connected to the feedback sampling resistor RL of the switching power supply.

[0022] The utility model provides a control circuit for adjusting the output voltage of a switching power supply. The circuit adjusts the bias voltage value of an operational amplifier input circuit, the gain multiple of a first adjustable gain circuit, the gain multiple of a second adjustable gain circuit, the voltage divider ratio of an operational control output circuit, the resistance ratio of a drive network circuit, and the drive feedback variable of a drive feedback circuit, and determines the voltage divider ratio of a feedback sampling resistor of the switching power supply. The above parameters are applied to the feedback sampling resistor of the switching power supply to achieve high-linearity adjustment control of the output voltage of the switching power supply. An optoelectronic isolation circuit is provided to achieve physical isolation between input and output, thereby avoiding mutual interference between input and output signals. Closed-loop feedback control is adopted to achieve voltage adaptive stable control. The circuit has a simple circuit structure and is easy to control, which is conducive to improving the control efficiency and reliability of the output voltage of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a diagram of the control circuit architecture for adjusting the output voltage of a switching power supply in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a control circuit for adjusting the output voltage of a switching power supply in an embodiment of the present utility model;

[0026] Figure 3 This is a schematic diagram of an operational amplifier circuit in an embodiment of the present utility model;

[0027] Figure 4 This is a schematic diagram of a photoelectric isolation circuit in an embodiment of the present utility model;

[0028] Figure 5 This is a schematic diagram of the operation control circuit in the embodiment of the utility model;

[0029] Figure 6 It is a schematic diagram of the driving control circuit in an embodiment of the present utility model. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] In the present invention, it should be understood that terms such as "include" or "have" are intended to indicate the existence of features, numbers, steps, behaviors, components, parts or their combinations disclosed in this specification, and are not intended to exclude the possibility of one or more other features, numbers, steps, behaviors, components, parts or their combinations existing or being added.

[0032] It should also be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] An embodiment of the utility model provides a control circuit for adjusting the output voltage of a switching power supply. The control circuit includes an operational amplifier circuit, a photoelectric isolation circuit, an operational control circuit, and a drive control circuit.

[0034] In an optional implementation of this embodiment, as Figure 1 and Figure 2 As shown, Figure 1 The control circuit structure diagram for adjusting the output voltage of the switching power supply in the embodiment of the present invention is shown. Figure 2 A schematic diagram of a control circuit for adjusting the output voltage of a switching power supply in an embodiment of the present invention is shown. The control circuit includes an operational amplifier circuit, an optoelectronic isolation circuit, an operational control circuit, and a drive control circuit. The input end of the operational amplifier circuit is the input port of the control circuit, the output end of the operational amplifier circuit is connected to the input end of the optoelectronic isolation circuit, the output end of the optoelectronic isolation circuit is connected to the input end of the operational control circuit, the output end of the operational control circuit is connected to the input end of the drive control circuit, the output end of the drive control circuit is the output port of the control circuit, and the output port of the control circuit is connected to the feedback sampling resistor of the switching power supply.

[0035] Specifically, the operational amplifier circuit is used for external control voltage signal input buffering and processing, the optoelectronic isolation circuit is used to physically isolate the input voltage signal and the output voltage signal, the operational control circuit is used to process the output voltage signal from the optoelectronic isolation circuit and perform related control, and the drive control circuit is used to provide stable control of the output impedance and realize adaptive impedance adjustment. The operational amplifier circuit, optoelectronic isolation circuit, operational control circuit and drive control circuit constitute a complete negative feedback closed-loop control voltage control circuit.

[0036] In an optional implementation of this embodiment, the operational amplifier circuit includes a first adjustable gain circuit and an operational amplifier input circuit.

[0037] In an optional implementation of this embodiment, as Figure 3 As shown, Figure 3 The schematic diagram of the operational amplifier circuit in an embodiment of the present utility model is shown. The first adjustable gain circuit includes an operational amplifier OP1, a resistor R1, a resistor R2, a resistor R3, and a capacitor C1. The inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R1, the first end of the resistor R2, and the first end of the capacitor C1. The output terminal of the operational amplifier OP1 is connected to the second ends of the resistor R1 and the capacitor C1. The non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R3.

[0038] Specifically, the first adjustable gain circuit is the adjustable gain of the operational amplifier circuit, and can be used to adjust the first gain multiple GAIN1 to adapt to different output voltage applications.

[0039] Furthermore, the resistance value of the resistor R1 is 10M, the resistance values ​​of the resistors R2 and R3 are 100k, and the capacitance value of the capacitor C1 is 1μ.

[0040] In an optional implementation of this embodiment, the operational amplifier input circuit includes an operational amplifier OP2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a capacitor C2. The inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R4, the first end of the resistor R5, and the first end of the resistor R6. The second end of the resistor R4 and the second end of the resistor R5 are grounded. The output terminal of the operational amplifier OP2 is connected to the second end of the resistor R6 and the second end of the resistor R2. The non-inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R7, the first end of the resistor R8, and the first end of the resistor R9. The second end of the resistor R7 is connected to the operational amplifier input voltage port VSET and the first end of the capacitor C2. The second end of the capacitor C2 is grounded. The second end of the resistor R8 is connected to the operational amplifier bias voltage port VBIAS. The second end of the resistor R9 is grounded.

[0041] Specifically, the operational amplifier input circuit includes two voltage port inputs, including an operational amplifier input voltage port VSET and an operational amplifier bias voltage port VBIAS. Both voltage port inputs are located at the op amp non-inverting input, forming an operational amplifier with settable bias. Subsequent output voltage adjustment can be achieved by adjusting the bias voltage input value VBIAS.

[0042] Furthermore, the resistance values ​​of the resistors R4 , R5 , R6 , R7 , R8 , and R9 are all 100k, and the capacitance value of the capacitor C2 is 0.1μ.

[0043] In an optional implementation of this embodiment, the operational amplifier circuit further includes an operational amplifier output circuit, which includes a resistor R10, a resistor R11, and a capacitor C3, wherein the first end of the resistor R10 is connected to the second end of the resistor R3, the second end of the resistor R10 is connected to the input first power supply port VDD1, the first end of the resistor R11 is connected to the output end of the operational amplifier OP1, the second end of the resistor R11 is connected to the first end of the capacitor C3, and the first end of the capacitor C3 is grounded.

[0044] Specifically, the operational amplifier output circuit is used to filter the output voltage signal of the operational amplifier circuit and then input the signal into the photoelectric isolation circuit for photoelectric isolation.

[0045] Furthermore, the resistance value of the resistor R10 is 100k, the resistance value of the resistor R11 is 510, and the capacitance value of the capacitor C3 is 0.1μ.

[0046] In an optional implementation of this embodiment, as Figure 4 As shown, Figure 4A schematic diagram of a photoelectric isolation circuit in an embodiment of the present invention is shown. The photoelectric isolation circuit includes a DC power supply isolation circuit, a photoelectric isolation input / output circuit, and a photoelectric isolation feedback circuit. The DC power supply isolation circuit is a neighboring power supply circuit and includes two branch circuits, one branch circuit connected to a first power supply port VDD1, and the other branch circuit connected to a second power supply port VDD2. The photoelectric isolation input / output circuit includes a first photoelectric isolator OC1, which includes a first light-emitting diode D1 and a first phototransistor Q1. The photoelectric isolation feedback circuit includes a second photoelectric isolator OC2, which includes a second light-emitting diode D2 and a second phototransistor Q2. The anode of the first light-emitting diode D1 and the collector of the second phototransistor Q2 are connected to the output of the operational amplifier circuit, the cathode of the first light-emitting diode D1 is connected to the anode of the second light-emitting diode D2, the collector of the first phototransistor Q1 is connected to the input of the operational control circuit, and the cathode of the second light-emitting diode D2, the emitter of the first phototransistor Q1, and the emitter of the second phototransistor Q2 are grounded.

[0047] Specifically, the photoelectric isolation input and output circuit provides photoelectric isolation, and the photoelectric isolation feedback circuit provides feedback on the isolation effect to stabilize the photoelectric isolation characteristics.

[0048] In an optional implementation of this embodiment, the operation control circuit includes a second adjustable gain circuit and an operation control output circuit.

[0049] In an optional implementation of this embodiment, as Figure 5 As shown, Figure 5 The schematic diagram of the operation control circuit in the embodiment of the present utility model is shown. The second adjustable gain circuit includes an operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, and a capacitor C4. The inverting input terminal of the operational amplifier OP3 is connected to the first end of the resistor R12, the first end of the resistor R13, and the first end of the capacitor C4. The output terminal of the operational amplifier OP3 is connected to the second ends of the resistor R12 and the capacitor C4. The non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R14.

[0050] Specifically, the second adjustable gain circuit is the adjustable gain of the operation control circuit, and can be used to adjust the second gain multiple GAIN2 to adapt to different output voltage applications.

[0051] Furthermore, the resistance value of the resistor R12 is 10M, the resistance values ​​of the resistors R13 and R14 are 100k, and the capacitance value of the capacitor C4 is 0.1μ.

[0052] In an optional implementation of this embodiment, the operational control output circuit includes an operational amplifier OP4, a resistor R15, a resistor R16, and a capacitor C5. The inverting input terminal and the output terminal of the operational amplifier OP4 are connected, and are also connected to the first end of the resistor R15 and the first end of the capacitor C5. The second end of the resistor R15 and the first end of the resistor R16 are connected to the second end of the resistor R14. The second end of the capacitor C5 and the second end of the resistor R16 are grounded.

[0053] Specifically, the arithmetic control output circuit is used to set the voltage division ratio RT1 and adjust the range and sensitivity of the output voltage.

[0054] Furthermore, the resistance value of the resistor R15 is 10k, the resistance value of the resistor R16 is 1k, and the capacitance value of the capacitor C5 is 0.1μ.

[0055] In an optional implementation of this embodiment, the operation control circuit further includes an operation control input circuit and an operation control feedback circuit, the operation control input circuit includes a resistor R17 and a resistor R18, the first end of the resistor R17 is connected to the second power supply port VDD2, the second end of the resistor R17 and the first end of the resistor R18 are connected to the output end of the optoelectronic isolation circuit, and the second end of the resistor R18 is connected to the non-inverting input end of the operational amplifier OP4; the operation control feedback circuit includes a capacitor C6, the first end of the capacitor C6 is connected to the second end of the resistor R13, and the second end of the capacitor C6 is grounded.

[0056] Specifically, the operation control input circuit is used to process the output voltage signal from the photoelectric isolation circuit, and the operation control feedback circuit is used to provide negative feedback control of the operation control circuit to ensure stable circuit operation.

[0057] Furthermore, the resistance values ​​of the resistors R17 and R18 are 100k, and the capacitance value of the capacitor C6 is 1μ.

[0058] In an optional implementation of this embodiment, the drive control circuit includes a drive network circuit and a drive feedback circuit.

[0059] In an optional implementation of this embodiment, as Figure 6 As shown, Figure 6 The schematic diagram of the drive control circuit in an embodiment of the present utility model is shown. The drive network circuit includes a resistor R19, a resistor R20, and a capacitor C7. The first end of the resistor R19 is connected to the output end of the operation control circuit, the second end of the resistor R19 is connected to the first end of the resistor R20 and the first end of the capacitor C7, and the second end of the resistor R20 and the second end of the capacitor C7 are grounded.

[0060] Specifically, the driving network circuit adjusts the linearity of the impedance conversion by setting different resistance ratios RT2.

[0061] Furthermore, the resistance value of the resistor R19 is 220, the resistance value of the resistor R20 is 100k, and the capacitance value of the capacitor C7 is 0.1μ.

[0062] In an optional implementation of this embodiment, the drive feedback circuit includes a resistor R21 , a first end of the resistor R21 is grounded, and a second end of the resistor R21 is connected to the second end of the resistor R13 and the first end of the capacitor C6 .

[0063] Specifically, the drive feedback circuit provides a feedback signal and a drive control feedback variable RFB.

[0064] Furthermore, the resistance value of the resistor R21 is 330.

[0065] In an optional implementation of this embodiment, the drive control circuit also includes a drive output circuit, which includes a transistor Q3 and a resistor R22. The base of the transistor Q3 is connected to the second end of the resistor R19, the first end of the resistor R20, and the first end of the capacitor C7. The emitter of the transistor Q3 is connected to the second end of the resistor R21, and the collector of the transistor Q3 is connected to the first end of the resistor R22.

[0066] Specifically, the drive output circuit is used to provide the impedance required by the circuit.

[0067] Furthermore, the resistance value of the resistor R22 is 1k.

[0068] In an optional implementation of this embodiment, the emitter of the transistor Q3 and the second end of the resistor R21 are connected to the first end of the capacitor C6 and the second end of the resistor R13.

[0069] Specifically, the feedback signal of the driving output circuit is connected to the operation control feedback circuit to form a closed-loop control circuit to achieve impedance adaptive adjustment.

[0070] In an optional implementation of this embodiment, the output port of the control circuit is connected to a feedback sampling resistor of the switching power supply.

[0071] Specifically, the second end of the resistor R22 is connected to the feedback sampling resistor RH of the switching power supply, and the first end of the resistor R21 is connected to the feedback sampling resistor RL of the switching power supply.

[0072] In an optional implementation of this embodiment, a twisted pair cable may be used as a connection line connecting the control circuit to the feedback sampling resistor of the switching power supply.

[0073] Working Principle: In this embodiment, the operational amplifier circuit amplifies and processes the input signal, the optoelectronic isolation circuit isolates the input signal from the output signal, the operational control circuit samples and converts it into an output signal and performs feedback control, and the drive control circuit controls the output signal to achieve stable control of the target output voltage required by the switching power supply.

[0074] In the actual operation of the control circuit of this embodiment, by adjusting the bias voltage input value VBIAS, the second gain multiple GAIN2, the voltage divider ratio RT1, and the drive control feedback variable RF (the sampling resistor voltage divider ratio RRT of the switching power supply can be considered here), the adjustment range value of the first gain multiple GAIN1 can be obtained. After the gain adjustment, the value is applied to the feedback sampling resistor of the switching power supply, and then the output voltage of the switching power supply is controlled, thereby achieving high-linearity adjustment and control of the output voltage of the switching power supply.

[0075] In summary, the embodiments of the present invention propose a control circuit for adjusting the output voltage of a switching power supply. By adjusting the bias voltage value of the operational amplifier input circuit, the gain multiple of the first adjustable gain circuit, the gain multiple of the second adjustable gain circuit, the voltage divider ratio of the operational control output circuit, the resistance ratio of the drive network circuit, and the drive feedback variable of the drive feedback circuit, and determining the voltage divider ratio of the feedback sampling resistor of the switching power supply, the above parameters are applied to the feedback sampling resistor of the switching power supply to achieve high-linearity adjustment control of the output voltage of the switching power supply; an optoelectronic isolation circuit is provided to achieve physical isolation between input and output, thereby avoiding mutual interference between the input signal and the output signal; closed-loop feedback control is adopted to achieve voltage adaptive stable control; the circuit structure is simple and the control is convenient, which is conducive to improving the control efficiency and reliability of the output voltage of the switching power supply.

[0076] The above is a detailed introduction to a control circuit for adjusting the output voltage of a switching power supply provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A control circuit for adjusting the output voltage of a switching power supply, characterized in that: The control circuit includes an operational amplifier circuit, a photoelectric isolation circuit, an operational control circuit and a drive control circuit; The input end of the operational amplifier circuit is the input port of the control circuit, the output end of the operational amplifier circuit is connected to the input end of the photoelectric isolation circuit, the output end of the photoelectric isolation circuit is connected to the input end of the operational control circuit, the output end of the operational control circuit is connected to the input end of the drive control circuit, and the output end of the drive control circuit is the output port of the control circuit; The operational amplifier circuit includes a first adjustable gain circuit and an operational amplifier input circuit, the operational control circuit includes a second adjustable gain circuit and an operational control output circuit, and the drive control circuit includes a drive network circuit and a drive feedback circuit; The output port of the control circuit is connected to the feedback sampling resistor of the switching power supply.

2. The control circuit for adjusting the output voltage of a switching power supply according to claim 1, wherein: The first adjustable gain circuit includes an operational amplifier OP1, a resistor R1, a resistor R2, a resistor R3, and a capacitor C1, wherein the inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R1, the first end of the resistor R2, and the first end of the capacitor C1, the output terminal of the operational amplifier OP1 is connected to the second ends of the resistor R1 and the capacitor C1, and the non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R3; The operational amplifier input circuit includes an operational amplifier OP2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, and a capacitor C2. The inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R4, the first end of the resistor R5, and the first end of the resistor R6. The second end of the resistor R4 and the second end of the resistor R5 are grounded. The output terminal of the operational amplifier OP2 is connected to the second end of the resistor R6 and the second end of the resistor R2. The non-inverting input terminal of the operational amplifier OP2 is connected to the first end of the resistor R7, the first end of the resistor R8, and the first end of the resistor R9. The second end of the resistor R7 is connected to the operational amplifier input voltage port VSET and the first end of the capacitor C2. The second end of the capacitor C2 is grounded. The second end of the resistor R8 is connected to the operational amplifier bias voltage port VBIAS. The second end of the resistor R9 is grounded.

3. The control circuit for adjusting the output voltage of a switching power supply according to claim 2, wherein: The operational amplifier circuit also includes an operational amplifier output circuit, which includes a resistor R10, a resistor R11, and a capacitor C3. The first end of the resistor R10 is connected to the second end of the resistor R3, the second end of the resistor R10 is connected to the input first power supply port VDD1, the first end of the resistor R11 is connected to the output end of the operational amplifier OP1, the second end of the resistor R11 is connected to the first end of the capacitor C3, and the first end of the capacitor C3 is grounded.

4. The control circuit for adjusting the output voltage of a switching power supply according to claim 1, wherein: The optoelectronic isolation circuit includes a DC power supply isolation circuit, an optoelectronic isolation input / output circuit, and an optoelectronic isolation feedback circuit. The DC power supply isolation circuit is a neighboring power supply circuit and includes two branch circuits, one branch circuit connected to the first power supply port VDD1, and the other branch circuit connected to the second power supply port VDD2. The optoelectronic isolation input / output circuit includes a first optoelectronic isolator OC1, which includes a first light-emitting diode D1 and a first phototransistor Q1. The optoelectronic isolation feedback circuit includes a second optoelectronic isolator OC2, which includes a second light-emitting diode D2 and a second phototransistor Q2. The anode of the first light-emitting diode D1 and the collector of the second phototransistor Q2 are connected to the output end of the operational amplifier circuit, the cathode of the first light-emitting diode D1 is connected to the anode of the second light-emitting diode D2, the collector of the first phototransistor Q1 is connected to the input end of the operational control circuit, and the cathode of the second light-emitting diode D2, the emitter of the first phototransistor Q1, and the emitter of the second phototransistor Q2 are grounded.

5. The control circuit for adjusting the output voltage of a switching power supply according to claim 1, wherein: The second adjustable gain circuit includes an operational amplifier OP3, a resistor R12, a resistor R13, a resistor R14, and a capacitor C4, wherein the inverting input terminal of the operational amplifier OP3 is connected to the first end of the resistor R12, the first end of the resistor R13, and the first end of the capacitor C4, the output terminal of the operational amplifier OP3 is connected to the second ends of the resistor R12 and the capacitor C4, and the non-inverting input terminal of the operational amplifier OP1 is connected to the first end of the resistor R14; The operational control output circuit includes an operational amplifier OP4, a resistor R15, a resistor R16, and a capacitor C5. The inverting input terminal and the output terminal of the operational amplifier OP4 are connected, and are also connected to the first end of the resistor R15 and the first end of the capacitor C5. The second end of the resistor R15 and the first end of the resistor R16 are connected to the second end of the resistor R14. The second end of the capacitor C5 and the second end of the resistor R16 are grounded.

6. The control circuit for adjusting the output voltage of a switching power supply according to claim 5, wherein: The operation control circuit further includes an operation control input circuit and an operation control feedback circuit, wherein the operation control input circuit includes a resistor R17 and a resistor R18, wherein a first end of the resistor R17 is connected to the second power supply port VDD2, a second end of the resistor R17 and a first end of the resistor R18 are connected to the output end of the photoelectric isolation circuit, and a second end of the resistor R18 is connected to the non-inverting input end of the operational amplifier OP4; The operation control feedback circuit includes a capacitor C6 , a first end of the capacitor C6 is connected to the second end of the resistor R13 , and a second end of the capacitor C6 is grounded.

7. The control circuit for adjusting the output voltage of a switching power supply according to claim 6, wherein: The driving network circuit includes a resistor R19, a resistor R20, and a capacitor C7, wherein a first end of the resistor R19 is connected to the output end of the operation control circuit, a second end of the resistor R19 is connected to a first end of the resistor R20 and a first end of the capacitor C7, and a second end of the resistor R20 and a second end of the capacitor C7 are grounded; The driving feedback circuit includes a resistor R21 , and a first end of the resistor R21 is grounded.

8. The control circuit for adjusting the output voltage of a switching power supply according to claim 7, wherein: The drive control circuit also includes a drive output circuit, which includes a transistor Q3 and a resistor R22. The base of the transistor Q3 is connected to the second end of the resistor R19, the first end of the resistor R20, and the first end of the capacitor C7. The emitter of the transistor Q3 is connected to the second end of the resistor R21. The collector of the transistor Q3 is connected to the first end of the resistor R22.

9. The control circuit for adjusting the output voltage of a switching power supply according to claim 8, wherein: The emitter of the transistor Q3 and the second end of the resistor R21 are connected to the first end of the capacitor C6 and the second end of the resistor R13.

10. The control circuit for adjusting the output voltage of a switching power supply according to claim 9, wherein: The second end of the resistor R22 is connected to the feedback sampling resistor RH of the switching power supply, and the first end of the resistor R21 is connected to the feedback sampling resistor RL of the switching power supply.

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