Overcurrent protection circuit of LED driving switching power supply

Abstract

The invention discloses an LED driving switch power supply over-current protection circuit which comprises a main side circuit and a secondary side circuit, the main side circuit comprises a first oscillation circuit and a second oscillation circuit, the first oscillation circuit comprises a first transistor, a first resistor, a first capacitor and a first main side coil, and the second oscillation circuit comprises a second transistor and a second capacitor. The first oscillation circuit comprises a first transistor, a first resistor and a first capacitor which are connected in series in a first main side coil closed circuit, the second oscillation circuit comprises a second transistor, a second resistor, a second capacitor and a second main side coil, and the second transistor, the second resistor and the second capacitor are connected in series in a second main side coil closed circuit; compared with the prior art, the LED driving switch power supply has the advantages that by adding the overcurrent protection design in the LED driving switch power supply, the LED driving switch power supply has good apparent power and stability, the number of loads can be increased according to actual requirements, a good heat dissipation effect is achieved, and cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of overcurrent protection of switching power supply circuits, and in particular to an overcurrent protection circuit of an LED driving switching power supply. Background Art

[0002] With the tense energy situation in the contemporary world, the use of energy-saving lighting fixtures has become increasingly important in reality. As a new type of lighting equipment, the relevant research on LED has received attention from many countries. Compared with the traditional light source, which is easy to pollute, difficult to start in low temperature environment and flammable at high temperature, LED has many advantages such as environmental protection, small size, long life, impact resistance, vibration resistance, high luminous efficiency, etc. In addition, the dimming method of LED is relatively simple, and the driving voltage is low, which makes LED have obvious application prospects. Although LED has many advantages, since LED has no infrared and ultraviolet radiation, the energy it releases is converted into light energy and also generates a lot of heat energy. If the LED is allowed to work at a high temperature for a long time, it is easy to burn. Therefore, the power of a single-chip LED is relatively small and the practicality is not high. Ordinary LED products on the market can control the input voltage outside the fluctuation range, but when the voltage is at the critical value, if there is no good protection measure, the load will be repeatedly affected by the impact current and even burn the load. Therefore, an overcurrent protection circuit of an LED driver switching power supply is provided to solve the above problems. . Summary of the invention

[0003] To solve the problems in the above background technology, the technical solution adopted by the present invention to solve the technical problems is: an overcurrent protection circuit of an LED driving switch power supply, which includes: a main side circuit and a secondary side circuit, the main side circuit has a first oscillation circuit and a second oscillation circuit, the first oscillation circuit includes a first transistor, a first resistor, a first capacitor, and a first main side coil, the first transistor, the first resistor, and the first capacitor are connected in series in a closed circuit of the first main side coil, the second oscillation circuit includes a second transistor, a second resistor, a second capacitor, and a second main side coil, the second transistor, the second resistor, and the second capacitor are connected in series in a closed circuit of the second main side coil.

[0004] As a preferred technical solution of the present invention, a third resistor is connected to the circuit between the first transistor and the first resistor, and one end of the first main side coil is connected to the third main side coil.

[0005] As a preferred technical solution of the present invention, a third capacitor and a fourth capacitor are connected in series in a circuit between the second transistor and the third resistor, and a circuit between the third capacitor and the fourth capacitor is connected to one end of the third main side coil.

[0006] As a preferred technical solution of the present invention, a first diode is connected between the first transistor and the first main side coil, and one end of the first diode is connected to a third resistor.

[0007] As a preferred technical solution of the present invention, a fourth resistor is connected to the line between the second transistor and the second resistor, one end of the fourth resistor is connected to the first diode, one end of the fourth resistor is connected to the second diode, and one end of the second diode is connected to the line between the second transistor and the second main side coil.

[0008] As a preferred technical solution of the present invention, one end of the first transistor is connected to the second transistor, and a third diode, a fourth diode, a fifth diode, and a sixth diode are connected between the other end of the first transistor and the second transistor.

[0009] As a preferred technical solution of the present invention, the third diode is connected in series with the fourth diode, the fifth diode is connected in series with the sixth diode, the line between the third diode and the fourth diode is connected to the first terminal, and the straight line between the fifth diode and the sixth diode is connected to the second terminal.

[0010] As a preferred technical solution of the present invention, the main side circuit includes a first side coil and a second side coil, the first side coil is connected in series in the LED circuit, one end of the second side coil is connected to a seventh diode, and the seventh diode is connected to a fifth capacitor.

[0011] As a preferred technical solution of the present invention, an eighth diode and a fifth resistor are connected in series between the first side coil and the LED, the eighth diode is connected to one end of the third transistor, and one end of the third transistor is connected to the second side coil.

[0012] The present invention has the following advantages: the present invention adds an overcurrent protection design to the LED driving switch power supply, thereby making it have good apparent power and stability, and can increase the number of loads according to actual requirements, has a good heat dissipation effect, and has a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall circuit of the switching power supply of the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention are described clearly and completely below. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Many specific details are explained in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0015] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Please refer to Figure 1 The present invention provides an overcurrent protection circuit for an LED driving switch power supply, comprising: a primary circuit and a secondary circuit, a first oscillation circuit and a second oscillation circuit of the primary circuit, the first oscillation circuit comprising a first transistor T1, a first resistor R3, a first capacitor C1, and a first primary coil L1, the first transistor T1, the first resistor R3, and the first capacitor C1 are connected in series in a closed circuit of the first primary coil L1, the second oscillation circuit comprises a first transistor T2, a second resistor R4, a second capacitor C2, and a second primary coil L2, the first transistor T2, the second resistor R4, and the second capacitor C2 are connected in series in a closed circuit of the second primary coil L2.

[0017] Among them, the line between the first transistor T1 and the first resistor R3 is connected to the third resistor R1, one end of the first main side coil L1 is connected to the third main side coil L3, the line between the first transistor T2 and the third resistor R1 is connected in series with the third capacitor C3 and the fourth capacitor C4, the line between the third capacitor C3 and the fourth capacitor C4 is connected to one end of the third main side coil L3, the line between the first transistor T1 and the first main side coil L1 is connected to the first diode D5, and one end of the first diode D5 is connected to the third resistor R1. Figure 1 The following is a white light LED driving circuit diagram, where the mains electricity is rectified by the D1-D4 bridge rectifier circuit and then filtered by C3 and C4 to obtain a voltage greater than 200V. L1, C1, R3 and the emission structure of T1 form an LC oscillation circuit with an oscillation frequency of 25KHz. Similarly, L2.C2, R4 and the emission of T2 form another LC oscillation circuit with an oscillation frequency of 25KHz and an opposite phase.

[0018] In the first oscillation loop formed by the emitter of L1, C1, R3, D5 and T1, when the current flows out from the 3rd port of the L1 coil through the emitter of C1, R3, T1 and returns to the 4th port of the L1 coil, T1 is in a saturated conduction state. Since the current outputs of L2 and L1 are in opposite phases, in the second oscillation loop formed by the emitter of L2, C2, R4 and D6, when the current flows out from the 7th port of the L2 coil through the emitter of D6, R4 and C2 and returns to the 6th port of L2, T2 is in a cut-off state.

[0019] A fourth resistor R2 is connected to the line between the first transistor T2 and the second resistor R4, one end of the fourth resistor R2 is connected to the first diode D5, one end of the fourth resistor R2 is connected to the second diode D6, one end of the second diode D6 is connected to the line between the first transistor T2 and the second main side coil L2, one end of the first transistor T1 is connected to the first transistor T2, the other end of the first transistor T1 and the line between the first transistor T2 are connected to the third diode D1, the fourth diode D3, the fifth diode D2, and the sixth diode D4, the third diode D1 and the fourth diode D3 are connected in series, the fifth diode D2 and the sixth diode D4 are connected in series, the line between the third diode D1 and the fourth diode D3 is connected to the first wiring terminal A, and the fifth diode D2 and the sixth diode D4 are connected to the second wiring terminal B. In the first oscillation loop formed by the emitter structure of L2, C2, R4, D6 and T2, when the current returns from the 6th port of the L2 coil through the emitter junction of C2, R4 and T2 to the 7th port of the L2 coil, T2 is in a saturated conduction state. Since T2 is in saturated conduction state, the current flows out from C4, passes through the first primary coil, flows out from port 4, flows into the collector and emitter junctions of T2, and returns to C4. At this time, C4 is discharged. Since T2 is in saturated conduction state, the current flowing from the power supply passes through C3 and the primary coil current, flows out from port 4, flows into the collector and emitter junctions of T2, and returns to the power supply to form another loop. At this time, the power supply charges C3.

[0020] Wherein, the main side circuit includes a first side coil L4 and a second side coil L5, the first side coil L4 is connected in series in the LED circuit, one end of the second side coil L5 is connected to the seventh diode D7, the seventh diode D7 is connected to the fifth capacitor C5, the circuit between the first side coil L4 and the LED is connected in series with an eighth diode D8 and a fifth resistor R5, the eighth diode D8 is connected to one end of the third transistor T3, one end of the third transistor T3 is connected to the second side coil L5, when the load is small, an induced voltage is generated in the first side coils L4 and L5, and a 6V DC voltage is obtained after rectification and filtering by D8 and C5, and a positive voltage is provided to the 8th pin of the 555 integrated block, when the load is not large, the voltage on R5 is low, and the 2nd pin of the 555 is at a high level through the photoelectric coupler IC2, the 6th pin is at a low level at the moment of power-on, the 3rd pin output is kept at a low level, and the 7th pin is in a conducting state, so that the collector of T3 outputs a high level to control the thyristor D7, which is in a conducting state, and the LED emits light normally. When the load is too large, the voltage on R5 will increase. When the voltage exceeds the upper limit of the protection, the 2nd pin of 555 is at a low level through the photocoupler IC2, triggering the 3rd pin to output a high level, so that the collector of T3 outputs a low level to control the thyristor D7 to be in the cut-off state, and no current passes through the LED circuit, which is in a protection state. When the load returns to normal value, the 2nd pin is at a high level, and the 6th pin gradually increases to a high level through the RC circuit, triggering the 3rd pin to output a low level, so that the collector of T3 outputs a high level to control the thyristor D7 to be in the on state, and the circuit resumes normal power supply.

[0021] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0022] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LED drive switching power supply overcurrent protection circuit, comprising: The main side circuit and the secondary side circuit are characterized in that the main side circuit has a first oscillation circuit and a second oscillation circuit, the first oscillation circuit includes a first transistor, a first resistor, a first capacitor, and a first main side coil, the first transistor, the first resistor, and the first capacitor are connected in series in the closed circuit of the first main side coil, and the second oscillation circuit includes a second transistor, a second resistor, a second capacitor, and a second main side coil, the second transistor, the second resistor, and the second capacitor are connected in series in the closed circuit of the second main side coil.

2. An LED drive switch power supply overcurrent protection circuit as claimed in claim 1, characterized in that: A third resistor is connected to a circuit between the first transistor and the first resistor, and a third main side coil is connected to one end of the first main side coil.

3. An LED drive switch power supply overcurrent protection circuit as claimed in claim 1, characterized in that: A third capacitor and a fourth capacitor are connected in series in a circuit between the second transistor and the third resistor, and a circuit between the third capacitor and the fourth capacitor is connected to one end of the third main side coil.

4. The LED driving switch power supply overcurrent protection circuit as claimed in claim 1, characterized in that: A first diode is connected to a line between the first transistor and the first main side coil, and one end of the first diode is connected to a third resistor.

5. The LED drive switch power supply overcurrent protection circuit according to claim 1, characterized in that: A fourth resistor is connected to the line between the second transistor and the second resistor, one end of the fourth resistor is connected to the first diode, one end of the fourth resistor is connected to the second diode, and one end of the second diode is connected to the line between the second transistor and the second main side coil.

6. An LED drive switch power supply overcurrent protection circuit as claimed in claim 1, characterized in that: One end of the first transistor is connected to the second transistor, and a line between the other end of the first transistor and the second transistor is connected to a third diode, a fourth diode, a fifth diode, and a sixth diode.

7. An LED drive switch power supply overcurrent protection circuit as claimed in claim 6, characterized in that: The third diode is connected in series with the fourth diode, the fifth diode is connected in series with the sixth diode, the line between the third diode and the fourth diode is connected to the first terminal, and the straight line between the fifth diode and the sixth diode is connected to the second terminal.

8. An overcurrent protection circuit for an LED driving switch power supply as claimed in claim 1, characterized in that: The main side circuit includes a first side coil and a second side coil, the first side coil is connected in series in the LED circuit, one end of the second side coil is connected to a seventh diode, and the seventh diode is connected to a fifth capacitor.

9. An overcurrent protection circuit for an LED driving switch power supply as claimed in claim 8, characterized in that: An eighth diode and a fifth resistor are connected in series in the circuit between the first side coil and the LED, the eighth diode is connected to one end of the third transistor, and one end of the third transistor is connected to the second side coil.

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