Switching power supply capable of limiting maximum power

Abstract

The utility model relates to the field of integrated circuits, in particular to a switching power supply capable of adjusting maximum power, which comprises a photoelectric coupler, a maximum power limiting module and a peripheral circuit. The input end of the maximum power limiting module is connected with the photoelectric coupler; the feedback end of the maximum power limiting module is connected with the photoelectric coupler through a peripheral circuit; the maximum power limiting module performs processing and feedback control on the working voltage output by the photoelectric coupler based on the auxiliary effect of a peripheral circuit, and realizes control on a primary PWM controller of the switching power supply through feedback so as to limit the maximum power; the maximum power limiting module comprises a receiving unit, a first control unit and a second control unit; the receiving unit receives the working voltage and outputs two paths of voltage; the first control unit and the second control unit respectively process and feed back the two paths of voltage and then output control voltage; and the maximum current is regulated and controlled by controlling the voltage so as to limit the maximum output power. The switching power supply can limit the maximum power.

Description

Technical Field

[0001] The utility model relates to the field of integrated circuits, in particular to a switching power supply capable of limiting maximum power. Background Art

[0002] A switching power supply is a high-frequency electric energy conversion device that converts a standard voltage into different output voltages through different forms of architecture. That is, it controls the on- and off-time ratio of the switching power supply to maintain a stable output voltage.

[0003] Switching power supplies are generally used in integrated circuits. In order to meet the needs of practical applications and improve the applicability of electronic products, the output power has a large range. However, in practice, excessive output may cause impacts on other components, affecting the safety and reliability of the product, and further affecting the safety of the use process. Therefore, the switching power supply or its applied integrated circuit sometimes needs to limit the maximum output power.

[0004] The UL 1310 standard is highly authoritative and recognized because it helps manufacturers ensure that their power products meet strict safety requirements, thus providing protection for end users. If you apply for UL1310 certification, it requires that the maximum power should not exceed 100W; if it exceeds 100W, PTC or FUSE needs to be added for overcurrent protection, thus achieving the effect of secondary protection; secondary protection means that under normal conditions, when the output end is short-circuited or overcurrent occurs, the protection circuit will act first, and only when the protection circuit fails to provide overcurrent protection or the protection circuit itself fails to provide short-circuit protection, will the PTC or FUSE have overcurrent protection action.

[0005] PTC can self-recover after overcurrent response; it is suitable for hot-swap applications, such as USB interfaces. Before the fault is eliminated, the recoverability of PTC leads to low safety, and the overcurrent response of PTC is slow. If the overcurrent lasts for a long time, the battery temperature will rise, making the use of the power supply unsafe.

[0006] FUSE is a one-time melting product. After filtering protection, PUSE will be melted, physically cutting off the circuit, completely protecting the circuit and eliminating safety hazards. However, after the secondary protection is activated, PUSE needs to be replaced, which is difficult for users to operate. At the same time, multiple replacements will continue to increase the cost of use. Utility Model Content

[0007] The utility model aims to provide a switching power supply capable of limiting the maximum power, so as to solve the problems of safety and high cost in the process of using the existing switching power supply.

[0008] The utility model provides a switching power supply capable of limiting maximum power, comprising a photoelectric coupler, a maximum power limiting module and a peripheral circuit; the photoelectric coupler outputs a working voltage; the input end of the maximum power limiting module is directly connected to the photoelectric coupler; the feedback end of the maximum power limiting module is connected to the photoelectric coupler through the peripheral circuit; the maximum power limiting module processes and feedback controls the working voltage output by the photoelectric coupler based on the auxiliary function of the peripheral circuit, and controls the primary PWM controller of the switching power supply through feedback to limit the maximum power;

[0009] Among them, the maximum power limiting module includes a receiving unit, a first control unit, and a second control unit; the receiving unit input is connected to a photoelectric coupler, and the receiving unit output is connected to the first control unit and the second control unit; the receiving unit receives the working voltage and outputs two voltages; the first control unit and the second control unit respectively process and feedback the two voltages and then output control voltages; the maximum current is regulated by the control voltage to limit the maximum output power.

[0010] Specifically, the receiving unit includes a dual op amp, a fifth resistor and a sixth resistor, the first output end of the dual op amp is connected to one end of the fifth resistor, and the other end of the fifth resistor is the second output end of the receiving unit; the first output end of the dual op amp is connected to one end of the sixth resistor, and the other end of the sixth resistor is the first output end of the receiving unit.

[0011] Specifically, the first control unit includes a first output branch, a first comparator and a power supply branch;

[0012] The first output branch is connected in parallel with the first comparator, the input end of the first output branch is connected to the output end of the first comparator, and the output end of the first output branch is connected to the inverting input end of the first comparator and the peripheral circuit; the output end of the first output branch is the sampling end of the maximum power limiting module; the peripheral circuit provides a first sampling voltage for the first comparator; the non-inverting input end of the first comparator is connected to the power supply branch; the power supply branch provides a first reference voltage for the non-inverting input end of the first comparator; the first comparator compares the first sampling voltage with the first reference voltage and then provides feedback.

[0013] Specifically, the peripheral circuit providing the first sampling voltage for the first comparator includes a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series and grounded through the fourth resistor; the connection point of the third resistor and the fourth resistor is connected to the sampling end of the maximum power limiting module.

[0014] Specifically, the first output branch includes a seventh resistor and a first capacitor; one end of the seventh resistor is connected to the first output end of the receiving unit, the other end of the seventh resistor is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the inverting input end of the first comparator and the peripheral circuit.

[0015] Specifically, the power supply branch includes a tenth resistor and a voltage reference chip, one end of the tenth resistor is connected to a power supply, the other end of the tenth resistor is connected to the cathode of the voltage reference chip, and the anode of the voltage reference chip is grounded; the connection point of the tenth resistor and the voltage reference chip in series is connected to the non-inverting input terminal of the first comparator, and the voltage reference chip provides a first reference voltage for the first comparator.

[0016] Specifically, the second control unit includes a second output branch, a second comparator and a potential adjustment module; the input end of the second output branch is connected to the second output end of the receiving unit and the output end of the second comparator, and the output end of the second output branch is the output end of the maximum power limiting module; the inverting input end of the second comparator is connected to the second output branch, and the second sampling voltage is obtained through the second output branch; the non-inverting input end of the second comparator is connected to the output end of the potential adjustment module and the peripheral circuit; the input end of the potential adjustment module is connected to the connection point in the power supply branch; the potential adjustment module adjusts the first reference voltage based on the peripheral circuit and outputs the second reference voltage.

[0017] Specifically, the second output branch includes a second capacitor, an eighth resistor and a ninth resistor; one end of the second capacitor is connected to the second output end of the receiving unit, the other end of the second capacitor is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to one end of the ninth resistor, and the other end of the ninth resistor is the output end of the maximum power limiting module; wherein the inverting input end of the second comparator is connected to the connection point of the eighth resistor and the ninth resistor.

[0018] Specifically, the peripheral circuit also includes a thirteenth resistor, one end of the thirteenth resistor is connected to the output end of the potential regulating module, and the other end of the thirteenth resistor is grounded; wherein the connection point between the thirteenth resistor and the potential regulating module is the regulating end of the maximum power limiting module.

[0019] Specifically, the potential adjustment module includes an eleventh resistor, a twelfth resistor and a potentiometer; the twelfth resistor and the potentiometer are connected in series and then connected in parallel with the eleventh resistor.

[0020] Compared with the prior art, the utility model has the following beneficial effects:

[0021] The utility model proposes a switching power supply capable of adjusting maximum power, comprising a maximum power limiting module connected to a photoelectric coupler and a peripheral circuit, wherein a first control unit and a second control unit of the maximum power limiting module compare and feedback-process two signals output by a receiving unit to output a control voltage, and the maximum current is regulated by the control voltage to limit the maximum output power, thereby achieving the effect of automatically adjusting and limiting the output of the maximum power; compared with the prior art which requires the replacement of a PTC or a FUSE, the utility model reduces costs and improves the safety and reliability of the use of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the utility model, the following is a brief introduction to the drawings required for use in the description of the embodiments. The drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 Shown is a circuit connection schematic diagram of a switching power supply capable of limiting the maximum power in the utility model. DETAILED DESCRIPTION

[0024] In order to further illustrate the technical means and effects adopted by the utility model, the specific implementation method, structure, characteristics and effects of the scheme of the utility model are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0025] The present invention provides a switching power supply capable of limiting the maximum power in a specific embodiment. Figure 1 As shown, it includes a photoelectric coupler, a maximum power limiting module and a peripheral circuit; the photoelectric coupler outputs a working voltage;

[0026] The input end of the maximum power limiting module is directly connected to the photoelectric coupler SK; the feedback end of the maximum power limiting module is connected to the photoelectric coupler through a peripheral circuit; the maximum power limiting module processes and feedback controls the working voltage output by the photoelectric coupler based on the auxiliary function of the peripheral circuit, and controls the primary PWM controller (not shown in the figure) of the switching power supply through feedback to limit the maximum power;

[0027] Among them, the maximum power limiting module includes a receiving unit, a first control unit, and a second control unit; the receiving unit input is connected to a photoelectric coupler, and the receiving unit output is connected to the first control unit and the second control unit; the receiving unit receives the working voltage and outputs two voltages; the first control unit and the second control unit respectively process and feedback the two voltages and then output control voltages; the maximum current is regulated by the control voltage to limit the maximum output power.

[0028] The utility model compares and performs feedback processing on two signals output by the receiving unit through the first control unit and the second control unit of the maximum power limiting module, thereby outputting a control voltage, and regulating the maximum current through the control voltage to achieve the limitation of the maximum output power, that is, it can automatically adjust the output of the limited maximum power.

[0029] In a specific embodiment of the present utility model, one implementation of the receiving unit of the maximum power limiting module is: including a dual operational amplifier D11, a fifth resistor R5 and a sixth resistor R6, wherein the first output end of the dual operational amplifier D11 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is the second output end of the receiving unit; the first output end of the dual operational amplifier D11 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is the first output end of the receiving unit. As other implementations, multiple resistors are included, or a splitter is used instead of the dual operational amplifier D11; or only two parallel branches of resistors are included; the present utility model does not limit the electrical components used in the receiving unit and their circuit connection relationship.

[0030] In a specific embodiment of the present utility model, the first control unit includes a first output branch, a first comparator and a power supply branch;

[0031] The first output branch is connected in parallel with the first comparator B1, the input end of the first output branch is connected to the output end of the first comparator B1, and the output end of the first output branch is connected to the inverting input end of the first comparator B1 and the peripheral circuit; the output end of the first output branch is the sampling end of the maximum power limiting module; the peripheral circuit provides a first sampling voltage for the first comparator B1; the non-inverting input end of the first comparator B1 is connected to the power supply branch; the power supply branch provides a first reference voltage for the non-inverting input end of the first comparator B1; the first comparator B1 compares the first sampling voltage with the first reference voltage and then provides feedback.

[0032] Specifically, the first comparator B1 is a BL358H operational amplifier chip. As other implementations, other types of chips or integrated chips may also be selected.

[0033] In a specific embodiment of the present utility model, the peripheral circuit that provides the first sampling voltage for the first comparator B1 includes a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series and grounded through the fourth resistor; the connection point of the third resistor and the fourth resistor is connected to the sampling end of the maximum power limiting module.

[0034] In a specific embodiment of the present utility model, the first output branch includes a seventh resistor R7 and a first capacitor C1; one end of the seventh resistor R7 is connected to the first output end of the receiving unit, the other end of the seventh resistor R7 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the inverting input end of the first comparator B1 and the peripheral circuit.

[0035] In a specific embodiment of the present utility model, the power supply branch includes a tenth resistor R10 and a voltage reference chip U, one end of the tenth resistor R10 is connected to a power supply VCC, the other end of the tenth resistor R10 is connected to a cathode of the voltage reference chip U, and the anode of the voltage reference chip U is grounded GND; the connection point of the tenth resistor R10 and the voltage reference chip U in series is connected to the non-inverting input terminal of the first comparator B1, and the voltage reference chip U provides a first reference voltage for the first comparator B1.

[0036] In a specific embodiment of the present utility model, the voltage reference chip U adopts ME431, which is a high-precision adjustable voltage reference chip, namely, a voltage reference chip. The voltage reference chip provides a first reference voltage of 2.5V to the in-phase input terminal of the first comparator B1.

[0037] In a specific embodiment of the present invention, the power supply range of the power supply VCC is 3 to 36V.

[0038] The first control unit of the utility model performs feedback control after comparing the first sampling voltage generated by the peripheral circuit with the first reference voltage.

[0039] In a specific embodiment of the utility model, the second control unit includes a second output branch, a second comparator B2 and a potential adjustment module; the input end of the second output branch is connected to the second output end of the receiving unit and the output end of the second comparator B2, and the output end of the second output branch is the output end of the maximum power limiting module; the inverting input end of the second comparator B2 is connected to the second output branch, and the second sampling voltage is obtained through the second output branch; the non-inverting input end of the second comparator B2 is connected to the output end of the potential adjustment module and the peripheral circuit; the input end of the potential adjustment module is connected to the connection point in the power supply branch; the potential adjustment module adjusts the first reference voltage based on the peripheral circuit and outputs the second reference voltage.

[0040] The utility model adjusts the first reference voltage through a potential adjustment module to obtain a second reference voltage, so that the second comparator compares the second reference voltage with the second sampling voltage and then feeds back.

[0041] In a specific embodiment of the utility model, the second output branch includes a second capacitor C2, an eighth resistor R8 and a ninth resistor R9; one end of the second capacitor C2 is connected to the second output end of the receiving unit, the other end of the second capacitor C2 is connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is the output end of the maximum power limiting module; wherein the inverting input end of the second comparator B2 is connected to the connection point of the eighth resistor R8 and the ninth resistor R9.

[0042] Specifically, the second comparator B2 is a BL358H operational amplifier chip. As other implementations, other types of chips or integrated chips may also be selected.

[0043] In a specific embodiment of the present utility model, the peripheral circuit for providing the second reference voltage for the second comparator B2 includes a thirteenth resistor R13, one end of the thirteenth resistor R13 is connected to the output end of the potential adjustment module, and the other end of the thirteenth resistor R13 is grounded; wherein the connection point between the thirteenth resistor R13 and the potential adjustment module is the control end of the maximum power limiting module.

[0044] In a specific embodiment of the present utility model, the potential regulating module includes an eleventh resistor R11, a twelfth resistor R12 and a potentiometer RP; the twelfth resistor R12 and the potentiometer RP are connected in series and then connected in parallel with the eleventh resistor R11. More specifically, one end of the eleventh resistor R11 is connected to the cathode and the reference end of the voltage reference chip U, and the other end of the eleventh resistor R11 is connected to the output end of the potential regulating module; one end of the potentiometer RP is connected to the cathode and the reference end of the voltage reference chip U, and the other end of the potentiometer RP is connected to the output end of the potential regulating module through the twelfth resistor R12.

[0045] The utility model adjusts the second reference voltage of the second comparator B2 by dividing the first reference voltage through the potential adjustment module and the thirteenth resistor in the peripheral circuit, so that the second comparator B2 compares the second reference voltage with the second sampling voltage for feedback.

[0046] The utility model can automatically adjust and limit the output of the maximum power through two-way sampling and comparison feedback of the first control unit and the second control unit; compared with the prior art that requires replacement of PTC or FUSE, the utility model reduces costs and improves the safety and reliability of the use of the switching power supply.

[0047] The peripheral circuit of the utility model further comprises a load resistor, one end of the load resistor RS is connected to the output end of the maximum power limiting module, and the other end of the load resistor RS outputs a control voltage.

[0048] In the utility model, the control voltage VOU generated after the current of the second output branch passes through the load resistor RS corresponds to the current value to be controlled; the maximum output power is limited by controlling the maximum current.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the utility model, which should be included in the scope of the technical solution for protection of the utility model.

Claims

1. A switching power supply capable of limiting maximum power, characterized in that: It includes a photoelectric coupler, a maximum power limiting module and a peripheral circuit; the photoelectric coupler outputs a working voltage; The input end of the maximum power limiting module is directly connected to the photoelectric coupler; the feedback end of the maximum power limiting module is connected to the photoelectric coupler through a peripheral circuit; the maximum power limiting module processes and feedback controls the working voltage output by the photoelectric coupler based on the auxiliary function of the peripheral circuit, and controls the primary PWM controller of the switching power supply through feedback to limit the maximum power; Among them, the maximum power limiting module includes a receiving unit, a first control unit, and a second control unit; the receiving unit input is connected to a photoelectric coupler, and the receiving unit output is connected to the first control unit and the second control unit; the receiving unit receives the working voltage and outputs two voltages; the first control unit and the second control unit respectively process and feedback the two voltages and then output control voltages; the maximum current is regulated by the control voltage to limit the maximum output power.

2. A switching power supply capable of limiting maximum power according to claim 1, characterized in that: The receiving unit includes a dual operational amplifier, a fifth resistor and a sixth resistor, wherein the first output end of the dual operational amplifier is connected to one end of the fifth resistor, and the other end of the fifth resistor is the second output end of the receiving unit; the first output end of the dual operational amplifier is connected to one end of the sixth resistor, and the other end of the sixth resistor is the first output end of the receiving unit.

3. A switching power supply capable of limiting maximum power according to claim 2, characterized in that: The first control unit includes a first output branch, a first comparator and a power supply branch; The first output branch is connected in parallel with the first comparator, the input end of the first output branch is connected to the output end of the first comparator, and the output end of the first output branch is connected to the inverting input end of the first comparator and the peripheral circuit; the output end of the first output branch is the sampling end of the maximum power limiting module; the peripheral circuit provides a first sampling voltage for the first comparator; the non-inverting input end of the first comparator is connected to the power supply branch; The power supply branch provides a first reference voltage for the non-inverting input terminal of the first comparator; the first comparator compares the first sampling voltage with the first reference voltage and then provides feedback.

4. A switching power supply capable of limiting maximum power according to claim 3, characterized in that: The peripheral circuit for providing the first comparator with the first sampling voltage includes a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series and grounded through the fourth resistor; the connection point of the third resistor and the fourth resistor is connected to the sampling end of the maximum power limiting module.

5. A switching power supply capable of limiting maximum power according to claim 3, characterized in that: The first output branch includes a seventh resistor and a first capacitor; one end of the seventh resistor is connected to the first output end of the receiving unit, the other end of the seventh resistor is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the inverting input end of the first comparator and the peripheral circuit.

6. A switching power supply capable of limiting maximum power according to claim 3, characterized in that: The power supply branch includes a tenth resistor and a voltage reference chip, one end of the tenth resistor is connected to the power supply, the other end of the tenth resistor is connected to the cathode of the voltage reference chip, and the anode of the voltage reference chip is grounded; the connection point between the tenth resistor and the voltage reference chip in series is connected to the non-inverting input terminal of the first comparator, and the voltage reference chip provides a first reference voltage for the first comparator.

7. A switching power supply capable of limiting maximum power according to claim 6, characterized in that: The second control unit includes a second output branch, a second comparator and a potential regulating module; the input end of the second output branch is connected to the second output end of the receiving unit and the output end of the second comparator, and the output end of the second output branch is the output end of the maximum power limiting module; the inverting input end of the second comparator is connected to the second output branch, and the second sampling voltage is obtained through the second output branch; the non-inverting input end of the second comparator is connected to the output end of the potential regulating module and the peripheral circuit; The input end of the potential regulating module is connected to a connection point in the power supply branch; the potential regulating module outputs a second reference voltage after regulating the first reference voltage based on a peripheral circuit.

8. A switching power supply capable of limiting maximum power according to claim 7, characterized in that: The second output branch includes a second capacitor, an eighth resistor and a ninth resistor; one end of the second capacitor is connected to the second output end of the receiving unit, the other end of the second capacitor is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to one end of the ninth resistor, and the other end of the ninth resistor is the output end of the maximum power limiting module; wherein the inverting input end of the second comparator is connected to the connection point of the eighth resistor and the ninth resistor.

9. A switching power supply capable of limiting maximum power according to claim 7, characterized in that: The peripheral circuit also includes a thirteenth resistor, one end of the thirteenth resistor is connected to the output end of the potential regulating module, and the other end of the thirteenth resistor is grounded; wherein the connection point between the thirteenth resistor and the potential regulating module is the regulating end of the maximum power limiting module.

10. The switching power supply capable of limiting maximum power according to claim 7, characterized in that: The potential adjustment module comprises an eleventh resistor, a twelfth resistor and a potentiometer; the twelfth resistor and the potentiometer are connected in series and then connected in parallel with the eleventh resistor.

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