High-efficiency power supply circuit of non-isolated step-down LED switching power supply

Abstract

The utility model discloses a high-efficiency power supply circuit of a non-isolated step-down LED switching power supply. The high-efficiency power supply circuit comprises an input EMI circuit, a bridge rectifier circuit, a capacitor filter circuit, an integrated control circuit, a control loop, a filter protection circuit, an OVP protection circuit, a CS sampling circuit and an output filter circuit which are connected in sequence. The output filter circuit is connected with the LED positive electrode and the LED negative electrode; the integrated control circuit comprises a chip U1, the chip U1 comprises two DRAIN pins, an HV pin, an OVP pin, a CS pin and a GND pin, and the GND pin is grounded; wherein the HV pin is connected with the cathode of the LED. According to the utility model, a novel power supply mode of LED cathode power supply is adopted, power is not directly taken from the rectified bus voltage, the power supply efficiency is improved, the cost is reduced, the energy loss is reduced, the heating problem is improved, and the stability and the reliability of the system are integrally improved.

Description

Technical Field

[0001] The utility model relates to the technical field of LED switching power supplies, and more specifically, to a high-efficiency power supply circuit of a non-isolated step-down LED switching power supply. Background Art

[0002] At present, the existing LED switching power supply circuit usually adopts the bus voltage power supply mode, that is, by distributing the high voltage to each module or chip that needs power supply, and then the power management unit (PMU) inside each module or chip performs voltage conversion and regulation to meet the voltage requirements of different modules. However, this bus voltage power supply mode has low power conversion efficiency, and there are serious problems of energy loss and heat generation. In addition, since it needs to go through multiple voltage conversions and distributions, it will cause large energy losses and heat generation, and it is necessary to use heat sinks and other equipment for heat dissipation. At the same time, it is easy to be affected by the impact of power on and off and lightning strikes, which can damage the IC.

[0003] Therefore, in order to avoid the shortcomings of the prior art, it is necessary to improve the prior art. Utility Model Content

[0004] The main purpose of the utility model is to overcome the above technical problems and provide a high-efficiency power supply circuit of a non-isolated step-down LED switching power supply.

[0005] To achieve the above-mentioned purpose, the utility model provides a high-efficiency power supply circuit of a non-isolated step-down LED switching power supply, comprising: an input EMI circuit, an integrated control circuit, a control loop, a filtering protection circuit and an output filtering circuit connected in sequence; the output filtering circuit is connected to the positive electrode of the LED and the negative electrode of the LED; the integrated control circuit comprises a chip U1, and the chip U1 comprises two DRAIN pins, an HV pin, an OVP pin, a CS pin and a GND pin, and the GND pin is grounded; wherein the HV pin is connected to the negative electrode of the LED.

[0006] The utility model adopts a new power supply mode of LED cathode power supply, instead of directly taking power from the rectified bus voltage, which improves power supply efficiency, reduces costs, reduces energy loss, improves heating problems, and improves overall system stability and reliability.

[0007] Furthermore, the input EMI circuit includes: a fuse F1 and an I-shaped inductor L1 connected in series with the mains live wire; a safety capacitor CX1 is electrically connected between the connection point of the fuse F1 and the I-shaped inductor L1 and the mains neutral wire, and a varistor RV1 is connected in parallel with the safety capacitor; and a chip resistor R1 is connected in parallel with the I-shaped inductor L1. It is used for overvoltage protection and improving the ability to resist lightning strikes and interference.

[0008] Furthermore, the control loop includes a diode D1 connected in series between two DRAIN pins of the chip U1 and the positive electrode of the LED, and a power inductor L2 connected in series between two DRAIN pins of the chip U1 and the negative electrode of the LED.

[0009] Furthermore, the filter protection circuit includes a capacitor C2 connected in series between the LED cathode and the ground. The method of taking power from the LED cathode and connecting the capacitor C2 in parallel to the ground can not only improve the power supply's surge resistance and switching impact capabilities, but also the capacitor C2 can absorb high-frequency interference caused by the inductor charging and discharging, which is beneficial to EMC performance.

[0010] Furthermore, the output filter circuit includes a resistor R2 and an electrolytic capacitor EC2 connected in parallel, wherein the connection point between one end of the resistor R2 and the positive electrode of the electrolytic capacitor EC2 is connected to the positive electrode of the LED, and the connection point between the other end of the resistor R2 and the negative electrode of the electrolytic capacitor EC2 is connected to the negative electrode of the LED for filtering.

[0011] Furthermore, it also includes a rectifier bridge stack circuit, a capacitor filter circuit, an OVP protection circuit and a CS sampling circuit. The rectifier bridge stack circuit and the capacitor filter circuit are sequentially connected between the input EMI circuit and the integrated control circuit.

[0012] Furthermore, the rectifier bridge stack circuit includes a rectifier bridge stack DB1, a first input terminal and a second input terminal of the rectifier bridge stack DB1 are respectively connected to the live wire and the neutral wire of the mains, a positive voltage first output terminal of the rectifier bridge stack DB1 is connected to the capacitor filter circuit and the positive electrode of the LED, and a negative voltage second output terminal of the rectifier bridge stack DB1 is grounded;

[0013] The capacitor filter circuit includes a CBB capacitor C1 and an electrolytic capacitor EC1, one end of the CBB capacitor C1, the positive electrode of the electrolytic capacitor EC1 and the positive voltage first output end of the rectifier bridge DB1 are connected, and the other end of the CBB capacitor C1, the negative electrode of the electrolytic capacitor EC1 and the negative voltage second output end of the rectifier bridge DB1 are connected. It is used to rectify and filter the input mains power and then supply power to the LED lamp.

[0014] Furthermore, the OVP protection circuit includes a resistor R3 connected to the OVP pin of the chip U1, which is used to provide protection for the downstream circuit from being damaged by an over-high voltage.

[0015] Furthermore, the CS sampling circuit includes a resistor RS1 and a resistor RS2 connected in parallel, which are connected to the CS pin of the chip U1 for sampling.

[0016] Furthermore, the chip U1 is a BP2866GJ chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 This is a circuit schematic diagram of a conventional bus voltage power supply method in the prior art;

[0019] Figure 2 A schematic diagram of a circuit module provided by the utility model;

[0020] Figure 3 The utility model provides a circuit diagram.

[0021] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrally formed connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0025] Example

[0026] like Figures 2-3As shown, a high-efficiency power supply circuit of a non-isolated step-down LED switching power supply includes: an input EMI circuit, a rectifier bridge circuit, a capacitor filter circuit, an integrated control circuit, a control loop, a filter protection circuit, an OVP protection circuit, a CS sampling circuit, and an output filter circuit connected in sequence; the output filter circuit is connected to the LED positive electrode and the LED negative electrode; the integrated control circuit includes a chip U1, and the chip U1 can adopt a BP2866GJ chip, including two DRAIN pins, an HV pin, an OVP pin, a CS pin and a GND pin, and the GND pin is grounded; wherein the HV pin is connected to the LED negative electrode.

[0027] In this embodiment, specifically: the input EMI circuit includes: a fuse F1 and an I-shaped inductor L1 connected in series with the live wire of the mains; a safety capacitor CX1 is electrically connected between the connection point of the fuse F1 and the I-shaped inductor L1 and the neutral wire of the mains, and a varistor RV1 connected in parallel with the safety capacitor; and a chip resistor R1 connected in parallel with the I-shaped inductor L1. The fuse F1 is connected in series with the live wire to prevent fire and other situations in the case of abnormal power supply, reduce user losses, and the fuse F1 can cut off the power supply in time when the power supply is abnormal to protect other electronic components.

[0028] Specifically: the rectifier bridge stack circuit includes a rectifier bridge stack DB1, a first input terminal and a second input terminal of the rectifier bridge stack DB1 are respectively connected to the live wire and the neutral wire of the mains, a positive voltage first output terminal of the rectifier bridge stack DB1 is connected to the capacitor filter circuit and the positive electrode of the LED, and a negative voltage second output terminal of the rectifier bridge stack DB1 is grounded;

[0029] The capacitor filter circuit includes a CBB capacitor C1 and an electrolytic capacitor EC1, one end of the CBB capacitor C1, the positive electrode of the electrolytic capacitor EC1 and the positive voltage first output end of the rectifier bridge DB1 are connected, and the other end of the CBB capacitor C1, the negative electrode of the electrolytic capacitor EC1 and the negative voltage second output end of the rectifier bridge DB1 are connected. It is used to rectify and filter the input mains power and then supply power to the LED lamp.

[0030] Specifically: the control loop includes a diode D1 connected in series between two common conductive DRAIN pins of the chip U1 and the LED anode, and a power inductor L2 connected in series between two common conductive DRAIN pins of the chip U1 and the LED cathode.

[0031] Specifically: The filter protection circuit includes a capacitor C2 connected in series between the negative electrode of the LED and the ground. The method of taking power from the negative electrode of the LED combined with the parallel capacitor C2 to the ground can not only improve the power supply's surge resistance and switching impact capabilities, but also the C2 capacitor can absorb high-frequency interference caused by the charging and discharging of the inductor, which is beneficial to EMC performance.

[0032] Specifically: The OVP protection circuit includes a resistor R3, which is connected to the OVP pin of the chip U1. It is used to provide protection for the downstream circuit to prevent it from being damaged by excessive voltage. The CS sampling circuit includes a resistor RS1 and a resistor RS2 in parallel, which are connected to the CS pin of the chip U1. It is used for sampling. The output filter circuit includes a resistor R2 and an electrolytic capacitor EC2 in parallel, and the connection point between one end of the resistor R2 and the positive electrode of the electrolytic capacitor EC2 is connected to the positive electrode of the LED, and the connection point between the other end of the resistor R2 and the negative electrode of the electrolytic capacitor EC2 is connected to the negative electrode of the LED; it is used for filtering.

[0033] It should be noted that the conventional method used in the prior art is bus voltage power supply, such as Figure 1 As shown in the figure, it distributes high voltage to each module or chip that needs power supply, and then the power management unit (PMU) inside each module or chip performs voltage conversion and regulation to meet the voltage requirements of different modules. Although this method has flexible power distribution, the power conversion efficiency is low, and there are problems of energy loss and serious heat generation. In the bus voltage power supply method, due to the need for multiple voltage conversions and distributions, large energy losses and high heat generation will occur, and heat sinks and other equipment are required for heat dissipation. In addition, it is easy to be affected by power on and off shocks and lightning strikes, which can easily damage the IC.

[0034] The utility model does not directly draw power from the rectified bus voltage, but draws power from the negative electrode of the LED. The use of electrolytic discharge resistors and LED voltage reduction and current limiting can save a resistor and space, thereby reducing costs. Figures 2-3 As shown, the 220V AC mains passes through the input fuse F1 and the EMI circuit, then passes through the rectifier bridge DB1 (AC-DC), passes through the capacitor filter circuit, and then passes through the output filter circuit to reach the negative electrode of the LED. The HV pin of the U1 chip supplies power to the entire circuit of the U1 chip, and the normal power supply of the light source is achieved by controlling the voltage reduction through the U1 chip.

[0035] By taking power from the negative pole of the LED, power loss can be reduced and power efficiency can be improved. It can be used to make Class 1 / Class 2 energy efficiency light source products with different light effect lamp beads. When the negative pole of the LED supplies power to the chip, since the negative pole is directly grounded, even if there is an abnormal situation such as a short circuit, the safety of the system can be guaranteed to a certain extent.

[0036] At the same time, the LED cathode power supply method reduces the number of voltage conversions, thereby reducing energy loss and improving the heating problem, which is beneficial to improving the stability and reliability of the system.

[0037] In practical applications, taking a 10W non-isolated step-down switching power supply as an example, the conversion efficiency of the output negative pole power supply method is usually about 0.58% higher than that of the bus voltage power supply method. The test data is shown in Table 1. From actual tests, under the same input and output voltage conditions, the lower the power of the power supply, the higher the relative increase in working efficiency.

[0038] Table 1

[0039]

[0040] It can be seen that the technical solution of using the LED cathode to power the chip adopted in this application can save finished products, improve power conversion efficiency, enhance system stability and reliability, and have higher overall performance compared to conventional power supply methods.

[0041] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A high-efficiency power supply circuit for a non-isolated buck LED switching power supply, characterized in that: include: An input EMI circuit, an integrated control circuit, a control loop, a filtering protection circuit and an output filtering circuit are connected in sequence; The output filter circuit is connected to the LED positive electrode and the LED negative electrode; The integrated control circuit includes a chip U1, and the chip U1 includes two DRAIN pins, a HV pin, an OVP pin, a CS pin and a GND pin, and the GND pin is grounded; Wherein, the HV pin is connected to the cathode of the LED.

2. A high-efficiency power supply circuit for a non-isolated step-down LED switching power supply according to claim 1, characterized in that: The input EMI circuit includes: a fuse F1 and an I-shaped inductor L1 connected in series with the mains live wire; a safety capacitor CX1 is electrically connected between the connection point of the fuse F1 and the I-shaped inductor L1 and the mains neutral wire, and a varistor RV1 is connected in parallel with the safety capacitor CX1; and a chip resistor R1 is connected in parallel with the I-shaped inductor L1.

3. The high-efficiency power supply circuit of a non-isolated step-down LED switching power supply according to claim 1, characterized in that: The control loop includes a diode D1 connected in series between two DRAIN pins of the chip U1 and the positive electrode of the LED, and a power inductor L2 connected in series between two DRAIN pins of the chip U1 and the negative electrode of the LED.

4. The high-efficiency power supply circuit of a non-isolated step-down LED switching power supply according to claim 1, characterized in that: The filtering protection circuit includes a capacitor C2 connected in series between the LED cathode and the ground.

5. The high-efficiency power supply circuit of a non-isolated step-down LED switching power supply according to claim 1, characterized in that: The output filter circuit includes a resistor R2 and an electrolytic capacitor EC2 connected in parallel, wherein a connection point between one end of the resistor R2 and the positive electrode of the electrolytic capacitor EC2 is connected to the positive electrode of the LED, and a connection point between the other end of the resistor R2 and the negative electrode of the electrolytic capacitor EC2 is connected to the negative electrode of the LED.

6. The high-efficiency power supply circuit of a non-isolated buck LED switching power supply according to claim 1, characterized in that: It also includes a rectifier bridge stack circuit, a capacitor filter circuit, an OVP protection circuit and a CS sampling circuit. The rectifier bridge stack circuit and the capacitor filter circuit are sequentially connected between the input EMI circuit and the integrated control circuit.

7. The high-efficiency power supply circuit of a non-isolated buck LED switching power supply according to claim 6, characterized in that: The rectifier bridge stack circuit includes a rectifier bridge stack DB1, wherein the first input terminal and the second input terminal of the rectifier bridge stack DB1 are respectively connected to the live wire and the neutral wire of the mains, the positive voltage first output terminal of the rectifier bridge stack DB1 is connected to the capacitor filter circuit and the positive electrode of the LED, and the negative voltage second output terminal of the rectifier bridge stack DB1 is grounded; The capacitor filter circuit includes a CBB capacitor C1 and an electrolytic capacitor EC1, one end of the CBB capacitor C1, the positive electrode of the electrolytic capacitor EC1 and the positive voltage first output end of the rectifier bridge stack DB1 are connected, and the other end of the CBB capacitor C1, the negative electrode of the electrolytic capacitor EC1 and the negative voltage second output end of the rectifier bridge stack DB1 are connected.

8. The high-efficiency power supply circuit of a non-isolated buck LED switching power supply according to claim 6, characterized in that: The OVP protection circuit includes a resistor R3 connected to the OVP pin of the chip U1.

9. The high-efficiency power supply circuit of a non-isolated buck LED switching power supply according to claim 6, characterized in that: The CS sampling circuit includes a resistor RS1 and a resistor RS2 connected in parallel and connected to a CS pin of the chip U1.

10. The high-efficiency power supply circuit of a non-isolated buck LED switching power supply according to claim 1, characterized in that: The chip U1 is a BP2866GJ chip.

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