Control linkage circuit of switching power supply

Abstract

The utility model discloses a control linkage circuit of a switching power supply, the control linkage circuit comprises M output branches, a feedback circuit and a drive control circuit, the output end of the first output branch is connected to the sampling input end of the input path of the drive control circuit, and the output end of the second output branch is connected to the sampling input end of the input path of the drive control circuit. The output end of the ith output branch is connected to the control end of the input path of the driving control circuit through the feedback circuit; the feedback circuit is used for switching on or switching off an input path of the driving control circuit; and the driving control circuit is used for controlling the output end of the switching power supply to execute a protection action on the M output branches according to the input voltage of the input path. According to the utility model, through the feedback circuit and the driving control circuit, when any output branch is short-circuited, powered down and abnormally too low in voltage, the short circuit, the power failure and the abnormally too low voltage can be fed back to the output end of the switching power supply, protection operation is executed, and the whole circuit is protected in a linkage manner, so that the product reliability and the working efficiency are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of switching power supplies, in particular to a control linkage circuit of a switching power supply. Background Art

[0002] A switching power supply is a high-frequency electric energy conversion device and a type of power supply. Compared with another power supply - a linear power supply, a switching power supply is widely used in industrial automation, military equipment, scientific research equipment, LED lighting, industrial control equipment, communication equipment, electric power industry, instrumentation, medical equipment, energy storage industry and other fields due to its high efficiency, small size and high reliability.

[0003] Switching power supplies are used in the power industry and energy storage industry. Switching power supplies are divided into single-channel output and multi-channel output. Multi-channel output is further divided into isolation and non-isolation. In the field of multi-channel isolation output, a separate transformer is generally used for power conversion and isolation. The voltage of each output needs to meet a high accuracy (±1%), which requires a separate voltage feedback circuit to be added to each output. In this context, there are the following obvious disadvantages in the application occasions:

[0004] When the main output is working normally, if one of the auxiliary outputs is abnormal, such as a short circuit at one output end due to external factors, the output abnormality will always have short-circuit power consumption, reducing the working efficiency of the power supply. The abnormal working of one channel will cause the control of other channels to work in abnormal state. At this time, the main output linkage protection cannot be achieved, and it works in abnormal state for a long time, seriously reducing the reliability of the product. Utility Model Content

[0005] The purpose of the utility model is to provide a control linkage circuit of a switching power supply, aiming to overcome the defect that one of the existing multi-channel isolated output circuits cannot be linked and controlled due to short circuit or abnormally low voltage, thereby shutting down the entire circuit system, and provide a linkage control solution, thereby solving the disadvantages of low working efficiency of the power supply due to the inability to link, long-term operation in an abnormal state, and seriously reducing product reliability.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] The utility model provides a control linkage circuit of a switching power supply, the control linkage circuit comprising M output branches, a feedback circuit and a drive control circuit, wherein M is an integer greater than or equal to 2;

[0008] The output end of the first output branch is connected to the sampling input end of the input path of the drive control circuit, and the output end of the i-th output branch is connected to the control end of the input path of the drive control circuit through the feedback circuit; wherein i is an integer greater than or equal to 2 and less than or equal to M;

[0009] The feedback circuit is used to turn on or off the input path of the drive control circuit according to the output voltage of the i-th output branch;

[0010] The drive control circuit is used to control the output end of the switching power supply to perform protection actions on the M output branches according to the input voltage of the input path.

[0011] Optionally, each of the output branches includes a first capacitor, a second capacitor and a first inductor, the first end of the first capacitor is connected to the output end of the switching power supply, the first end of the first capacitor is connected to the first end of the second capacitor through the first inductor, the second end of the first capacitor and the second end of the second capacitor are both connected to a reference ground, and the first end of the second capacitor serves as the output end of the output branch.

[0012] Optionally, the feedback circuit includes N feedback units, where N=M-1;

[0013] The output end of the i-th output branch is connected one by one to the input end of the j-th feedback unit; wherein j is an integer greater than or equal to 1 and less than or equal to N.

[0014] Optionally, each of the feedback units includes a first resistor and an optocoupler, the anode of the optocoupler diode of the optocoupler is connected to the output end of the corresponding output branch through the first resistor, the cathode of the optocoupler diode of the optocoupler is connected to the reference ground, and the collector and emitter of the optocoupler transistor of the optocoupler are connected to the corresponding ports of the control end of the input path.

[0015] Optionally, each of the feedback units also includes a sampling circuit, which is connected between the cathode of the optocoupler diode of the optocoupler and a reference ground, the first end of the sampling circuit is respectively connected to the cathode and anode of the optocoupler diode of the optocoupler, the second end of the sampling circuit is connected to the reference ground, and the control end of the sampling circuit is also connected to the output end of the corresponding output branch.

[0016] Optionally, the sampling circuit includes a second resistor, a third resistor, a fourth resistor and a controllable precision voltage-stabilizing source, the first end of the second resistor is connected to the output end of the corresponding output branch, the second end of the second resistor is connected to the reference ground through the third resistor, the second end of the second resistor is also connected to the reference electrode of the controllable precision voltage-stabilizing source, the cathode of the controllable precision voltage-stabilizing source is connected to the anode of the optocoupler diode of the optocoupler through the fourth resistor, the cathode of the controllable precision voltage-stabilizing source is also connected to the cathode of the optocoupler diode of the optocoupler, and the anode of the controllable precision voltage-stabilizing source is connected to the reference ground.

[0017] Optionally, the drive control circuit includes a first voltage regulator tube, a fifth resistor, a sixth resistor, a first diode, a first switch tube and a second switch tube, the first end of the fifth resistor is connected to the output end of the first output branch, the second end of the fifth resistor is connected to the cathode of the first voltage regulator tube through the input path, the anode of the first voltage regulator tube is connected to the control end of the first switch tube, the first end of the first switch tube is connected to the first end of the first switch tube through the sixth resistor, the first end of the first switch tube is connected to the anode of the first diode, the cathode of the first diode is connected to the control end of the second switch tube, the first end of the second switch tube is connected to the output end of the switching power supply, and the second ends of the first switch tube and the second ends of the second switch tube are both connected to the reference ground.

[0018] Optionally, the drive control circuit includes a first voltage regulator tube, a second voltage regulator tube, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first switch tube and a second switch tube, the first end of the fifth resistor is connected to the output end of the first output branch, the second end of the fifth resistor is connected to the cathode of the first voltage regulator tube through the input path, the anode of the first voltage regulator tube is connected to the control end of the first switch tube, the first end of the first switch tube is connected to the anode of the second voltage regulator tube, the cathode of the second voltage regulator tube is connected to the power supply end through the sixth resistor, the anode of the second voltage regulator tube is connected to the control end of the second switch tube through the eighth resistor, the first end of the second switch tube is connected to the feedback end of the switching power supply through the seventh resistor, and the second end of the first switch tube and the second end of the second switch tube are both connected to the reference ground.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] The utility model uses a feedback circuit and a drive control circuit to feedback to the output end of the switching power supply in a circuit with multiple output branches when any output branch has a short circuit, power failure or abnormally low voltage, so as to perform a protection operation and then link the protection of the entire circuit, thereby improving product reliability and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a circuit principle diagram of the first embodiment of a control linkage circuit of a switching power supply of the utility model;

[0022] Figure 2 It is a circuit principle diagram of a second embodiment of a control linkage circuit of a switching power supply of the utility model;

[0023] Figure 3 It is a circuit principle diagram of a third embodiment of a control linkage circuit of a switching power supply of the utility model;

[0024] Figure 4 This is a circuit schematic diagram of a fourth embodiment of a control linkage circuit of a switching power supply of the utility model. DETAILED DESCRIPTION

[0025] The present invention and its beneficial effects will be further described in detail below in conjunction with specific implementation methods and the accompanying drawings of the specification; however, the specific implementation methods of the present invention / invention are not limited thereto.

[0026] The embodiment of the utility model provides a control linkage circuit of a switching power supply, which includes M output branches 100, a feedback circuit 200 and a drive control circuit 300, wherein M is an integer greater than or equal to 2;

[0027] The output end of the first output branch 100 is connected to the sampling input end of the input path of the driving control circuit 300, and the output end of the i-th output branch 100 is connected to the control end of the input path of the driving control circuit 300 through the feedback circuit 200; wherein i is an integer greater than or equal to 2 and less than or equal to M;

[0028] The feedback circuit 200 is used to turn on or off the input path of the drive control circuit 300 according to the output voltage of the i-th output branch 100;

[0029] The drive control circuit 300 is used to control the output end of the switching power supply to perform a protection action on the M output branches 100 according to the input voltage of the input path.

[0030] First embodiment

[0031] like Figure 1 The circuit diagram of the embodiment of the utility model is shown, and the principle is explained by taking two output branches 100 of the circuit. The circuit includes a first output branch 100 , a second output branch 100 , a feedback circuit 200 , and a drive control circuit 300 .

[0032] The first output branch 100 and the second output branch 100 respectively include: a first capacitor C1, a second capacitor C2 and a first inductor L1, the first end of the first capacitor C1 is connected to the output end of the switching power supply, the first end of the first capacitor C1 is connected to the first end of the second capacitor C2 through the first inductor L1, the second end of the first capacitor C1 and the second end of the second capacitor C2 are both connected to the reference ground, and the first end of the second capacitor C2 serves as the output end of the output branch 100.

[0033] The feedback circuit 200 includes N feedback units 201, wherein N=M-1; the output end of the i-th output branch 100 is connected to the input end of the j-th feedback unit 201 one by one; wherein j is an integer greater than or equal to 1 and less than or equal to N. Each feedback unit 201 includes a first resistor R1 and an optical coupler U1; the anode of the optical coupling diode of the optical coupler U1 is connected to the output end of the corresponding output branch 100 through the first resistor R1, the cathode of the optical coupling diode of the optical coupler U1 is connected to the reference ground, and the collector and emitter of the optical coupling transistor of the optical coupler U1 are connected to the corresponding ports of the control end of the input path.

[0034] The driving control circuit 300 includes a first voltage regulator tube Z1, a fifth resistor R5, a sixth resistor R6, a first diode D1, a first switch tube Q1, and a second switch tube Q2. The first end of the fifth resistor R5 is connected to the output end of the first output branch 100, the second end of the fifth resistor R5 is connected to the cathode of the first voltage regulator tube Z1 through the input path, the anode of the first voltage regulator tube Z1 is connected to the control end of the first switch tube Q1, the first end of the first switch tube Q1 is connected to the first end of the first switch tube Q1 through the sixth resistor R6, the first end of the first switch tube Q1 is connected to the anode of the first diode D1, the cathode of the first diode D1 is connected to the control end of the second switch tube Q2, the first end of the second switch tube Q2 is connected to the output end of the switching power supply, and the second end of the first switch tube Q1 and the second end of the second switch tube Q2 are both connected to the reference ground. In this embodiment, the first switch tube Q1 is an NPN transistor, the control end of the first switch tube Q1 is the base, the first end is the collector, and the second end is the emitter. The second switch tube Q2 is a thyristor, the control end of the second switch tube Q2 is a control electrode, the first end is an anode, and the second end is a cathode.

[0035] The working principle of this embodiment is as follows:

[0036] When the first output branch 100 and the second output branch 100 are working normally, the positive electrode VO2+ of the output voltage of the second output branch 100 acts on the anode of the optocoupler diode in the optocoupler U1 through the first resistor R1, and the cathode of the optocoupler diode is connected to the negative electrode VO2- of the output voltage of the second output branch 100. At this time, the optocoupler diode inside the optocoupler U1 works normally and emits light, and the optocoupler transistor inside the optocoupler U1 receives the optical signal to turn on the optocoupler transistor of the optocoupler U1. The output voltage V01+ of the first output branch 100 is connected to the base of the first switch tube Q1 after passing through the fifth resistor R5, the optical coupler U1, and the first voltage regulator tube Z1. The emitter of the transistor is grounded, and the first switch tube Q1 works in the saturation region. At this time, the base and emitter voltages of the first switch tube Q1 are forward biased and the voltage drop therebetween is minimal. At this time, the collector voltage of the first switch tube Q1 pulls down the anode of the first diode D1, controlling the second switch tube Q2 to be non-conductive, and the first output branch 100 and the second output branch 100 work normally.

[0037] When the output terminal Vo1+ of the first output branch 100 is short-circuited to the ground, no matter whether the output of the second output branch 100 is normal or not, the main controller of the switching power supply will enter the protection state to protect the entire circuit.

[0038] When the first output branch 100 works normally and the output end of the second output branch 100 is short-circuited due to an abnormality, the output voltage Vo2+ of the second output branch 100 is close to 0V, and the positive electrode Vo2+ of the output voltage of the second output branch 100 acts on the anode of the optocoupler diode in the optocoupler U1 through the first resistor R1, and the cathode of the optocoupler diode is connected to the negative electrode Vo1- of the output voltage of the first output branch 100. At this time, the optocoupler diode inside the optocoupler U1 does not work, and the optocoupler transistor inside the optocoupler U1 cannot receive the optical signal, causing the optocoupler transistor to be in a high-impedance non-conducting state. Therefore, the input path between the optical coupler U1 and the fifth resistor R5 and the first voltage regulator tube Z1 is open circuit, so the base voltage of the first switch tube Q1 is low level, and the first switch tube Q1 works in the cut-off state. At this time, the anode of the first diode D1 will not be pulled down by the first switch tube Q1, and the sixth resistor R6 provides a driving signal to the second switch tube Q2 through the first diode D1 to turn it on. At this time, the output end of the first output branch 100 is short-circuited, so that the main controller of the switching power supply enters the protection state, thereby linking to protect the entire circuit.

[0039] Second embodiment

[0040] like Figure 2The schematic diagram of the second embodiment of the utility model after the circuit is expanded on the basis of the first embodiment is shown, and the circuit includes a first output branch 100, a second output branch 100, an N-th output branch 100, a feedback circuit 200 and a drive control circuit 300. The first output branch 100, the second output branch 100 to the N-th output branch 100 respectively include: a first capacitor C1, a second capacitor C2 and a first inductor L1, the first end of the first capacitor C1 is connected to the output end of the switching power supply, the first end of the first capacitor C1 is connected to the first end of the second capacitor C2 through the first inductor L1, the second end of the first capacitor C1 and the second end of the second capacitor C2 are both connected to the reference ground, and the first end of the second capacitor C2 serves as the output end of the output branch 100.

[0041] The feedback circuit 200 includes N feedback units 201, wherein N=M-1; the output end of the i-th output branch 100 is connected to the input end of the j-th feedback unit 201 one by one; wherein j is an integer greater than or equal to 1 and less than or equal to N. Each feedback unit 201 includes a first resistor R1 and an optical coupler U1; the anode of the optical coupling diode of the optical coupler U1 is connected to the output end of the corresponding output branch 100 through the first resistor R1, the cathode of the optical coupling diode of the optical coupler U1 is connected to the reference ground, and the collector and emitter of the optical coupling transistor of the optical coupler U1 are connected to the corresponding ports of the control end of the input path.

[0042] The driving control circuit 300 includes a first voltage regulator tube Z1, a fifth resistor R5, a sixth resistor R6, a first diode D1, a first switch tube Q1, and a second switch tube Q2. The first end of the fifth resistor R5 is connected to the output end of the first output branch 100, the second end of the fifth resistor R5 is connected to the cathode of the first voltage regulator tube Z1 through the input path, the anode of the first voltage regulator tube Z1 is connected to the control end of the first switch tube Q1, the first end of the first switch tube Q1 is connected to the first end of the first switch tube Q1 through the sixth resistor R6, the first end of the first switch tube Q1 is connected to the anode of the first diode D1, the cathode of the first diode D1 is connected to the control end of the second switch tube Q2, the first end of the second switch tube Q2 is connected to the output end of the switching power supply, and the second end of the first switch tube Q1 and the second end of the second switch tube Q2 are both connected to the reference ground. In this embodiment, the first switch tube Q1 is an NPN transistor, the control end of the first switch tube Q1 is the base, the first end is the collector, and the second end is the emitter. The second switch tube Q2 is a thyristor, the control end of the second switch tube Q2 is a control electrode, the first end is an anode, and the second end is a cathode.

[0043] The working principle of the utility model is as follows:

[0044] The first output branch 100, the second output branch 100 and the Nth output branch 100 all work normally. The positive electrodes VO2+ and VOn+ of the output voltages of the second output branch 100 and the Nth output branch 100 act on the anode of the optocoupler diode in the optocoupler U1 through the first resistor R1 respectively, and the cathode of the optocoupler diode is connected to the negative electrode VO2- of the output voltage of the second output branch 100 and the positive electrode VOn- of the output voltage of the Nth output branch 100 respectively. Only when the second output branch 100 and the Nth output branch 100 are operating normally, the optocoupler transistor of the optocoupler U1 presents low impedance, the internal optocoupler diode operates normally and emits light, the emitter of the transistor is grounded, and the first switch tube Q1 operates in the saturation region. At this time, the base and emitter voltages of the first switch tube Q1 are forward biased and the voltage drop therebetween is minimal. The collector voltage of the first switch tube Q1 pulls down the anode of the first diode D1, controls the second switch tube Q2 to be non-conductive, and the first output branch 100, the second output branch 100, and the Nth output branch 100 all operate normally.

[0045] When the output terminal Vo1+ of the first output branch 100 is short-circuited to ground, no matter whether the output voltages of the second output branch 100 and the Nth output branch 100 are normal or not, the main controller of the switching power supply will enter the protection state to protect the entire circuit.

[0046] When the first output branch 100 works normally, and the second output branch 100 or the Nth output branch 100 is short-circuited at the output end due to an abnormality, the output voltage VO2+ or VOn+ of the second output branch 100 or the Nth output branch 100 is close to 0V, and the internal optocoupler diode of the optocoupler U1 does not work. The optocoupler transistor inside the optocoupler U1 cannot receive the optical signal, so that the optocoupler transistor presents a high impedance non-conducting state. Therefore, the input path of the optocoupler U1 is in an open circuit state, and the base voltage of the first switch tube Q1 is at a low level, and the first switch tube Q1 works in a cut-off state. At this time, the anode of the first diode D1 will not be pulled down by the first switch tube Q1, and the sixth resistor R6 provides a driving signal to the second switch tube Q2 through the first diode D1 to turn it on. At this time, the output end of the first output branch 100 is short-circuited, so that the main controller of the switching power supply enters a protection state, thereby protecting the entire circuit in a linked manner.

[0047] Third embodiment

[0048] like Figure 3 The circuit diagram of the third embodiment of the utility model is shown, and the principle is explained by using two output branches 100 of the circuit. The circuit includes a first output branch 100, a second output branch 100, a feedback circuit 200 and a drive control circuit 300.

[0049] The first output branch 100 and the second output branch 100 respectively include: a first capacitor C1, a second capacitor C2 and a first inductor L1, the first end of the first capacitor C1 is connected to the output end of the switching power supply, the first end of the first capacitor C1 is connected to the first end of the second capacitor C2 through the first inductor L1, the second end of the first capacitor C1 and the second end of the second capacitor C2 are both connected to the reference ground, and the first end of the second capacitor C2 serves as the output end of the output branch 100.

[0050] The feedback circuit 200 includes a feedback unit 201, and the output end of the second output branch 100 is connected to the input end of the feedback unit 201. The feedback unit 201 includes a first resistor R1 and an optical coupler U1; the anode of the optical coupling diode of the optical coupler U1 is connected to the output end of the corresponding output branch 100 through the first resistor R1, the cathode of the optical coupling diode of the optical coupler U1 is connected to the reference ground, and the collector and emitter of the optical coupling transistor of the optical coupler U1 are connected to the corresponding port of the control end of the input path. Each feedback unit 201 also includes a sampling circuit 202, which is connected between the cathode of the optical coupling diode of the optical coupler U1 and the reference ground, the first end of the sampling circuit 202 is respectively connected to the cathode and anode of the optical coupling diode of the optical coupler U1, the second end of the sampling circuit 202 is connected to the reference ground, and the control end of the sampling circuit 202 is also connected to the output end of the corresponding output branch 100. The sampling circuit 202 includes a second resistor R2, a third resistor R3, a fourth resistor R4 and a controllable precision voltage-stabilizing source U3, wherein the first end of the second resistor R2 is connected to the output end of the corresponding output branch 100, the second end of the second resistor R2 is connected to the reference ground through the third resistor R3, the second end of the second resistor R2 is also connected to the reference electrode of the controllable precision voltage-stabilizing source U3, the cathode of the controllable precision voltage-stabilizing source U3 is connected to the anode of the optocoupler diode of the optocoupler U1 through the fourth resistor R4, the cathode of the controllable precision voltage-stabilizing source U3 is also connected to the cathode of the optocoupler diode of the optocoupler U1, and the anode of the controllable precision voltage-stabilizing source U3 is connected to the reference ground.

[0051] The drive control circuit 300 includes a first voltage regulator tube Z1, a second voltage regulator tube Z2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first switch tube Q1 and a second switch tube Q2. The first end of the fifth resistor R5 is connected to the output end of the first output branch 100, the second end of the fifth resistor R5 is connected to the cathode of the first voltage regulator tube Z1 through the input path, the anode of the first voltage regulator tube Z1 is connected to the control end of the first switch tube Q1, the first end of the first switch tube Q1 is connected to the anode of the second voltage regulator tube Z2, the cathode of the second voltage regulator tube Z2 is connected to the power supply end through the sixth resistor R6, the anode of the second voltage regulator tube Z2 is connected to the control end of the second switch tube Q2 through the eighth resistor R8, the first end of the second switch tube Q2 is connected to the feedback end of the switching power supply through the seventh resistor R7, and the second end of the first switch tube Q1 and the second end of the second switch tube Q2 are both connected to the reference ground.

[0052] The working principle of the utility model is as follows:

[0053] When the first output branch 100 and the second output branch 100 are both working normally, the voltage after voltage division of the positive electrode VO2+ of the output voltage of the second output branch 100 through the second resistor R2 and the third resistor R3 is compared with the reference voltage of the controllable precision voltage regulator U3. When the first output branch 100 and the second output branch 100 are both working normally, the voltage after voltage division is greater than the reference voltage, so that the controllable precision voltage regulator U3 is in a low impedance state. At this time, the optocoupler diode inside the optocoupler U1 works normally and emits light, and the optocoupler transistor inside the optocoupler U1 receives the optical signal to turn on the optocoupler transistor of the optocoupler U1. The output voltage V01+ of the first output branch 100 is connected to the base of the first switch tube Q1 after passing through the fifth resistor R5, the optical coupler U1, and the first voltage regulator tube Z1. The emitter of the first switch tube Q1 is grounded, and the first switch tube Q1 operates in the saturation region. At this time, the base and emitter voltages of the first switch tube Q1 are positively biased and the voltage drop therebetween is minimal. At this time, the collector voltage of the first switch tube Q1 pulls down the base voltage of the second switch tube Q2 through the sixth resistor R6 to make it work in the cut-off region. The collector and emitter of the second switch tube Q2 present a high impedance, so it does not affect the feedback voltage output to the feedback terminal FB during normal operation. Both the first output branch 100 and the second output branch 100 can operate normally.

[0054] When the output terminal Vo1+ of the first output branch 100 is short-circuited to the ground, no matter whether the output of the second output branch 100 is normal or not, the main controller of the switching power supply will enter the protection state to protect the entire circuit.

[0055] When the first output branch 100 works normally, and the output end of the second output branch 100 is short-circuited or the voltage abnormally drops to outside the controllable voltage due to an abnormality, the output voltage VO2+ of the second output branch 100 after voltage division by the second resistor R2 and the third resistor R3 is lower than the controllable precision voltage regulator U3, so the controllable precision voltage regulator U3 is in a low-impedance conduction state, and the positive electrode Vo2+ of the output voltage of the second output branch 100 acts on the anode of the optocoupler diode in the optocoupler U1 through the first resistor R1. At this time, the optocoupler diode inside the optocoupler U1 works, and the optocoupler transistor inside the optocoupler U1 receives the optical signal, causing the optocoupler transistor to be in a low-impedance conduction state. The base and emitter voltages of the first switch tube Q1 are not forward biased, and the collector and emitter of the first switch tube Q1 are in a high-impedance off state. The VCC1 voltage forward biases the base and emitter voltages of the second switch tube Q2 through the sixth resistor R6, the second voltage regulator tube Z2 and the eighth resistor R8, so that the base and emitter voltages of the second switch tube Q2 work in the saturation region. The collector and emitter of the second switch tube Q2 are in a low-impedance on state, which lowers the feedback voltage of the feedback terminal FB, thereby causing the main controller of the switching power supply to enter a protection state, thereby protecting the entire circuit in a linked manner.

[0056] Fourth embodiment

[0057] like Figure 4 The fourth embodiment of the utility model is shown as a schematic diagram of the fourth embodiment, which is expanded on the basis of the third embodiment circuit. The present embodiment can theoretically expand an infinite number of output branches 100. The principle is described below. The circuit includes a first output branch 100, a second output branch 100, an Nth output branch 100, a feedback circuit 200 and a drive control circuit 300.

[0058] The first output branch 100, the second output branch 100 to the Nth output branch 100 respectively include: a first capacitor C1, a second capacitor C2 and a first inductor L1, the first end of the first capacitor C1 is connected to the output end of the switching power supply, the first end of the first capacitor C1 is connected to the first end of the second capacitor C2 through the first inductor L1, the second end of the first capacitor C1 and the second end of the second capacitor C2 are both connected to the reference ground, and the first end of the second capacitor C2 serves as the output end of the output branch 100.

[0059] The feedback circuit 200 includes N feedback units 201, wherein N=M-1; the output end of the i-th output branch 100 is connected to the input end of the j-th feedback unit 201 one by one; wherein j is an integer greater than or equal to 1 and less than or equal to N. Each feedback unit 201 includes a first resistor R1 and an optical coupler U1; the anode of the optical coupling diode of the optical coupler U1 is connected to the output end of the corresponding output branch 100 through the first resistor R1, the cathode of the optical coupling diode of the optical coupler U1 is connected to the reference ground, and the collector and emitter of the optical coupling transistor of the optical coupler U1 are connected to the corresponding ports of the control end of the input path. Each feedback unit 201 further includes a sampling circuit 202, which is connected between the cathode of the optocoupler diode of the optocoupler U1 and the reference ground, a first end of the sampling circuit 202 is respectively connected to the cathode and anode of the optocoupler diode of the optocoupler U1, a second end of the sampling circuit 202 is connected to the reference ground, and a control end of the sampling circuit 202 is also connected to the output end of the corresponding output branch 100. The sampling circuit 202 includes a second resistor R2, a third resistor R3, a fourth resistor R4 and a controllable precision voltage-stabilizing source U3, wherein the first end of the second resistor R2 is connected to the output end of the corresponding output branch 100, the second end of the second resistor R2 is connected to the reference ground through the third resistor R3, the second end of the second resistor R2 is also connected to the reference electrode of the controllable precision voltage-stabilizing source U3, the cathode of the controllable precision voltage-stabilizing source U3 is connected to the anode of the optocoupler diode of the optocoupler U1 through the fourth resistor R4, the cathode of the controllable precision voltage-stabilizing source U3 is also connected to the cathode of the optocoupler diode of the optocoupler U1, and the anode of the controllable precision voltage-stabilizing source U3 is connected to the reference ground.

[0060] The drive control circuit 300 includes a first voltage regulator tube Z1, a second voltage regulator tube Z2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first switch tube Q1 and a second switch tube Q2. The first end of the fifth resistor R5 is connected to the output end of the first output branch 100, the second end of the fifth resistor R5 is connected to the cathode of the first voltage regulator tube Z1 through the input path, the anode of the first voltage regulator tube Z1 is connected to the control end of the first switch tube Q1, the first end of the first switch tube Q1 is connected to the anode of the second voltage regulator tube Z2, the cathode of the second voltage regulator tube Z2 is connected to the power supply end through the sixth resistor R6, the anode of the second voltage regulator tube Z2 is connected to the control end of the second switch tube Q2 through the eighth resistor R8, the first end of the second switch tube Q2 is connected to the feedback end of the switching power supply through the seventh resistor R7, and the second end of the first switch tube Q1 and the second end of the second switch tube Q2 are both connected to the reference ground.

[0061] The working principle of the utility model is as follows:

[0062] The first output branch 100, the second output branch 100 and the Nth output branch 100 all work normally. The voltages of the positive electrodes VO2+ and VOn+ of the output voltages of the second output branch 100 and the Nth output branch 100 after being divided by the second resistor R2 and the third resistor R3 in the output voltage feedback circuit 200 are higher than the reference voltage of the controllable precision voltage regulator U3. At this time, the light-emitting diodes inside the optical coupler U1 all work normally and emit light. The emitter of the first switch tube Q1 is grounded. At this time, the base and emitter voltages of the first switch tube Q1 are forward biased and the voltage drop therebetween is minimal. The first switch tube Q1 works in the saturation region. The collector voltage of the first switch tube Q1 pulls down the base voltage of the second switch tube Q2 through the sixth resistor R6, so that the base and emitter voltages of the second switch tube Q2 are not forward biased and are in a cut-off high-impedance off state. Therefore, the feedback voltage of the feedback terminal FB during normal operation is not affected, and all output branches 100 can work normally.

[0063] When the output terminal Vo1+ of the first output branch 100 is short-circuited to ground, no matter whether the output voltages of the second output branch 100 and the Nth output branch 100 are normal or not, the main controller of the switching power supply will enter the protection state to protect the entire circuit.

[0064] When the first output branch 100 works normally, the output end of the second output branch 100 or the Nth output branch 100 is short-circuited or the voltage abnormally drops to outside the controllable voltage, that is, the output voltage VO2+ and VOn+ of the second output branch 100 or the Nth output branch 100 are respectively divided by the second resistor R2 and the third resistor R3, which are lower than the feedback reference voltage. Therefore, as long as there is one optocoupler U1 in each feedback unit 201 in the high impedance off state, the series circuit of the optocoupler triode of the optocoupler U1 will no longer present a low impedance on state. At this time, the first switch tube Q1 does not work, and the VCC1 voltage makes the base and emitter voltage of the second switch tube Q2 positively biased through the sixth resistor R6, the second voltage regulator tube Z2 and the eighth resistor R8, so that it works in the saturation region, and the collector and emitter of the second switch tube Q2 present a low impedance on state, which pulls down the feedback voltage of the feedback end FB of the switching power supply, thereby causing the main controller of the switching power supply to enter the protection state, thereby protecting the entire circuit in a linked manner.

[0065] The above implementation cases are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention. In addition, without departing from the spirit and scope of the present invention, several improvements and modifications can be made, which are obviously obtained through the existing known technology. These improvements and modifications should also be regarded as the protection scope of the present invention, and will not be repeated in the embodiments here.

Claims

1. A control linkage circuit of a switching power supply, characterized in that: The control linkage circuit includes M output branches, a feedback circuit and a drive control circuit, wherein M is an integer greater than or equal to 2; The output end of the first output branch is connected to the sampling input end of the input path of the drive control circuit, and the output end of the i-th output branch is connected to the control end of the input path of the drive control circuit through the feedback circuit; wherein i is an integer greater than or equal to 2 and less than or equal to M; The feedback circuit is used to turn on or off the input path of the drive control circuit according to the output voltage of the i-th output branch; The drive control circuit is used to control the output end of the switching power supply to perform protection actions on the M output branches according to the input voltage of the input path.

2. The control linkage circuit of a switching power supply according to claim 1, characterized in that: Each of the output branches includes a first capacitor, a second capacitor and a first inductor, the first end of the first capacitor is connected to the output end of the switching power supply, the first end of the first capacitor is connected to the first end of the second capacitor through the first inductor, the second end of the first capacitor and the second end of the second capacitor are both connected to a reference ground, and the first end of the second capacitor serves as the output end of the output branch.

3. The control linkage circuit of a switching power supply according to claim 1, characterized in that: The feedback circuit includes N feedback units, wherein N=M-1; The output end of the i-th output branch is connected one by one to the input end of the j-th feedback unit; wherein j is an integer greater than or equal to 1 and less than or equal to N.

4. The control linkage circuit of a switching power supply according to claim 3, characterized in that: Each feedback unit includes a first resistor and an optocoupler, the anode of the optocoupler diode of the optocoupler is connected to the output end of the corresponding output branch through the first resistor, the cathode of the optocoupler diode of the optocoupler is connected to the reference ground, and the collector and emitter of the optocoupler transistor of the optocoupler are connected to the corresponding ports of the control end of the input path.

5. The control linkage circuit of a switching power supply according to claim 4, characterized in that: Each of the feedback units also includes a sampling circuit, which is connected between the cathode of the optocoupler diode of the optocoupler and a reference ground, the first end of the sampling circuit is respectively connected to the cathode and anode of the optocoupler diode of the optocoupler, the second end of the sampling circuit is connected to the reference ground, and the control end of the sampling circuit is also connected to the output end of the corresponding output branch.

6. The control linkage circuit of a switching power supply according to claim 5, characterized in that: The sampling circuit includes a second resistor, a third resistor, a fourth resistor and a controllable precision voltage-stabilizing source, wherein the first end of the second resistor is connected to the output end of the corresponding output branch, the second end of the second resistor is connected to the reference ground through the third resistor, the second end of the second resistor is also connected to the reference electrode of the controllable precision voltage-stabilizing source, the cathode of the controllable precision voltage-stabilizing source is connected to the anode of the optocoupler diode of the optocoupler through the fourth resistor, the cathode of the controllable precision voltage-stabilizing source is also connected to the cathode of the optocoupler diode of the optocoupler, and the anode of the controllable precision voltage-stabilizing source is connected to the reference ground.

7. The control linkage circuit of a switching power supply according to claim 1, characterized in that: The drive control circuit includes a first voltage regulator tube, a fifth resistor, a sixth resistor, a first diode, a first switch tube and a second switch tube. The first end of the fifth resistor is connected to the output end of the first output branch, the second end of the fifth resistor is connected to the cathode of the first voltage regulator tube through the input path, the anode of the first voltage regulator tube is connected to the control end of the first switch tube, the first end of the first switch tube is connected to the first end of the first switch tube through the sixth resistor, the first end of the first switch tube is connected to the anode of the first diode, the cathode of the first diode is connected to the control end of the second switch tube, the first end of the second switch tube is connected to the output end of the switching power supply, and the second ends of the first switch tube and the second ends of the second switch tube are both connected to the reference ground.

8. The control linkage circuit of a switching power supply according to claim 1, characterized in that: The drive control circuit includes a first voltage regulator tube, a second voltage regulator tube, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first switch tube and a second switch tube. The first end of the fifth resistor is connected to the output end of the first output branch, the second end of the fifth resistor is connected to the cathode of the first voltage regulator tube through the input path, the anode of the first voltage regulator tube is connected to the control end of the first switch tube, the first end of the first switch tube is connected to the anode of the second voltage regulator tube, the cathode of the second voltage regulator tube is connected to the power supply end through the sixth resistor, the anode of the second voltage regulator tube is connected to the control end of the second switch tube through the eighth resistor, the first end of the second switch tube is connected to the feedback end of the switching power supply through the seventh resistor, and the second end of the first switch tube and the second end of the second switch tube are both connected to the reference ground.

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