CN213991098U

CN213991098U - LED drive circuit with protection function

Info

Publication number: CN213991098U
Application number: CN202022828328.6U
Authority: CN
Inventors: 曹胜军; 吕少华; 蒲纪忠; 甘彩英; 赵艺佼
Original assignee: CH Lighting Technology Co Ltd
Current assignee: CH Lighting Technology Co Ltd
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2021-08-17
Anticipated expiration: 2030-11-30

Abstract

The application discloses LED drive circuit with protect function, including rectifier circuit, filter circuit and the constant current circuit who couples in proper order, the constant current circuit includes the constant current chip who couples filter circuit through a supply circuit, supply circuit is including the first switch element of its break-make of control, first switch element has the control end, the control end couples filter circuit through an undervoltage protection circuit and an overvoltage crowbar respectively, detects filter circuit and surpasss the threshold value of settlement for the supply voltage of constant current chip when undervoltage protection circuit or overvoltage crowbar, then controls first switch element and is in the off-state. This application is through parallelly connected undervoltage protection circuit and the overvoltage protection circuit who sets up, and control first switching element switches on in setting for the voltage threshold, avoids constant current chip to lead to damaging because of voltage fluctuation, has improved life.

Description

LED drive circuit with protection function

Technical Field

The utility model relates to an electricity field especially relates to a LED drive circuit with protect function.

Background

At present, a plurality of electronic devices on the market have strict requirements on input or output voltage signals, and when the voltage signals are too high, the service life of the electronic devices is easily influenced, and even the electronic devices are directly burnt; when the voltage signal is too low, damage may also be caused to the electronic device.

In order to minimize the damage to the electronic devices, circuits are introduced to protect the electronic devices. The novel alternating current protection circuit comprises an undervoltage protection circuit and an overvoltage protection circuit, alternating current in the undervoltage protection circuit is divided and then rectified into smoother voltage to be provided for a second reference source, the voltage of a second capacitor end is changed simultaneously when the voltage of an input power grid is changed, the voltage value is provided for the second reference source, the second reference source outputs a high-resistance state when the voltage of the second capacitor end is lower than 2.5V, a base electrode pin of a triode is raised through a ninth resistor to raise the level, a pulse control chip is closed, and the work is stopped; alternating current in the overvoltage protection circuit is divided into smooth voltage after rectification and then is supplied to the first reference source for detection, when the input power grid is increased, the voltage of the first capacitor end is also increased until the voltage is greater than or equal to 2.5V, the first reference source conducts the second reference source and simultaneously outputs a high-resistance state, the base electrode pin of the triode is raised to a level through the ninth resistor, the pulse control chip is closed, and the work is stopped.

The circuit can effectively avoid the influence of voltage on the electronic device, thereby ensuring the safety of the electronic device. However, this circuit uses many electronic components and has a complicated structure.

SUMMERY OF THE UTILITY MODEL

The utility model provides a LED drive circuit with protect function has solved and has used electronic components more, the more complicated problem of structure.

The utility model provides a LED drive circuit with protect function, is including rectifier circuit, filter circuit and the constant current circuit that couples in proper order, the constant current circuit includes the constant current chip who couples filter circuit through a supply circuit, supply circuit includes the first switch element of its break-make of control, first switch element has the control end, the control end is respectively through an undervoltage protection circuit and an overvoltage crowbar coupling filter circuit.

Several alternatives are provided below, but not as an additional limitation to the above general solution, but merely as a further addition or preference, each alternative being combinable individually for the above general solution or among several alternatives without technical or logical contradictions.

Optionally, the power supply circuit includes a first resistor, a second resistor, and a fourth resistor connected in series in sequence, and the first switching element is disposed between the second resistor and the fourth resistor.

Optionally, the power supply circuit includes a first inductor, a first diode, and a third resistor connected in series in sequence, where the first inductor is grounded, and the third resistor is connected in series with the second resistor.

Optionally, the under-voltage protection circuit includes a first zener diode and a fifth resistor connected in series, the first zener diode is coupled to the filter circuit, and the fifth resistor is coupled to the control terminal of the first switching element.

Optionally, the overvoltage protection circuit includes a second switching element having a control end, and a second zener diode and a sixth resistor connected in series, where the control end of the first switching element is grounded through the second switching element, the second zener diode is coupled to the filter circuit, and the sixth resistor is coupled to the control end of the second switching element.

Optionally, the second switching element is a transistor Q2, and a base of the transistor Q2 is a control terminal thereof.

Optionally, the first switching element is a transistor Q1, and a base of the transistor Q1 is a control terminal thereof.

Optionally, the constant current circuit includes an MOS transistor controlled by the constant current chip and an energy storage freewheeling unit.

Optionally, the energy storage freewheeling comprises a second inductor and a second diode, and the anode of the second diode and the second inductor are both coupled to the drain of the MOS transistor.

Optionally, the filter circuit is an LC filter circuit.

The utility model discloses an under-voltage protection circuit and the overvoltage crowbar of parallelly connected setting control first switch element and switch on in setting for the voltage threshold, avoid constant current chip to lead to damaging because of voltage fluctuation, improved life, also simplified circuit structure simultaneously.

Drawings

FIG. 1 is a schematic diagram of an LED driver circuit according to the present application;

FIG. 2 is a schematic circuit diagram of the rectifier circuit of FIG. 1;

FIG. 3 is a circuit schematic of the filter circuit of FIG. 1;

FIG. 4 is a circuit schematic of a prior art constant current circuit;

fig. 5 is a schematic circuit diagram of a constant current circuit in the LED driving circuit according to the present invention.

The reference numerals in the figures are illustrated as follows:

1. a constant current chip;

10. a rectifying circuit;

20. a filter circuit;

30. a constant current circuit; 31. a power supply circuit; 32. an undervoltage protection circuit; 33. an overvoltage protection circuit; 34. and the energy storage follow current unit.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The existing common LED power supply circuit comprises a rectifying circuit, a filter circuit and a constant current circuit, but in the actual use process, because the voltage of a power grid is unstable, a certain damage can be caused to a constant current chip.

In order to reduce the influence of voltage instability on the constant current chip, undervoltage protection and overvoltage protection circuits are provided on the market, so that the safety of electronic devices can be effectively guaranteed, but in the existing protection circuit, the used electronic components are more in types and the structure is more complex.

In order to solve the problem, the utility model provides a simpler LED drive circuit who has protect function of structure, as shown in fig. 1 ~ 3 and 5, it is including rectifier circuit 10, filter circuit 20 and the constant current circuit 30 that couple in proper order, and constant current circuit 30 includes the constant current chip 1 who couples filter circuit 20 through a supply circuit 31, and supply circuit 31 is including the first switch element of its break-make of control, and first switch element has the control end, the control end is coupled to filter circuit 20 through an undervoltage protection circuit 32 and an overvoltage protection circuit 33 respectively, detects filter circuit 20 and surpasss the threshold value of settlement for the supply voltage of constant current chip 1 when undervoltage protection circuit 32 or overvoltage protection circuit 33, then controls first switch element and is in the off-state.

As shown in fig. 1, in the present application, a rectification circuit 10 rectifies mains supply, converts ac power into dc power, inputs the dc power into a filter circuit 20 for filtering, obtains a relatively flat voltage, and inputs the finally output voltage into a constant current circuit 30, so that the constant current circuit obtains stable dc power for normal operation of LEDs.

The rectifier circuit 10 and the filter circuit 20 of the present application may adopt the prior art, and in this embodiment, the rectifier circuit 10 is a bridge rectifier circuit, and the filter circuit 20 is an LC filter circuit.

In an embodiment, as shown in fig. 2, the live line L is connected in series with a fuse F1, a rectifier bridge DB1, and a neutral line N in sequence, and a voltage dependent resistor RV1, a resistor R30 and a resistor R31 connected in series, and a capacitor C1 are arranged between the fuse F1 and the neutral line N in parallel.

In the filter circuit 20 shown in fig. 3, the output terminal of the rectifier bridge DB1 is coupled to one terminal of the inductor L3, the other terminal of L3 is coupled to the varistor RV2 and the capacitor C4, respectively, and the other terminals of the varistor RV2 and the capacitor C4 are grounded together with the other terminal of the rectifier bridge DB 1. The inductor L3 is also connected in parallel with a resistor R10.

As shown in fig. 4, the conventional power supply circuit includes a first resistor R1, a second resistor R2, and a fourth resistor R4 connected in series in sequence, wherein the resistors form a voltage dividing circuit coupled to the VCC terminal of the constant current chip for providing a start voltage. In order to maintain the voltage stability, the power supply circuit further includes a first inductor TL1B, a first diode D1, and a third resistor R3 connected in series, wherein the first inductor TL1B is grounded, and the third resistor R3 is coupled to a node between the second resistor R2 and the fourth resistor R4.

In an embodiment, the power supply circuit further includes a MOS transistor Q3 controlled by the constant current chip 1 and an energy storage freewheeling unit 34, the energy storage freewheeling includes a second inductor TL1A and a second diode D2, an anode of the second diode D2 and the second inductor TL1A are both coupled to the drain of the MOS transistor Q3, and the DRV terminal of the constant current chip 1 is coupled to the gate of the MOS transistor Q3 through a resistor R13. The resistor R12 and the capacitor C12 which are connected in series are connected in parallel with the second diode D2, and the cathode of the second diode D2 and the output end of the filter circuit 20 are connected in parallel with the electrolytic capacitor C9, the capacitor C11 and the resistor R7.

In order to solve the influence of large voltage fluctuation on the constant current chip 1, the overvoltage protection circuit 32 and the overvoltage protection circuit 33 are added on the basis of the existing power supply circuit.

In one embodiment, the power supply circuit 31 of the present application is provided with a first switching element, and the first switching element is disposed between the second resistor R2 and the fourth resistor R4.

In an embodiment, the under-voltage protection circuit 32 includes a first zener diode Z1 and a fifth resistor R5 connected in series, the first zener diode Z1 is coupled to the filter circuit 20, and the fifth resistor R5 is coupled to the control terminal of the first switch element.

In one embodiment, the overvoltage protection circuit 33 includes a second switching element having a control terminal, and a second zener diode Z2 and a sixth resistor R6 connected in series, where the control terminal of the first switching element is grounded through the second switching element, the second zener diode Z2 is coupled to the filter circuit 20, and the sixth resistor R6 is coupled to the control terminal of the second switching element.

In this embodiment, the first switching element is a transistor Q1, and the base of the transistor Q1 is the control terminal. The second switching element is a transistor Q2, the base of which is the control terminal of a transistor Q2.

When a power supply is started, a current passes through the rectifying circuit 10 and the filter circuit 20, passes through the first resistor R1, the second resistor R2 and a collector of the triode Q1, and simultaneously, when the voltage is within a normal range threshold value, a certain high-level value is reached to break down the first voltage-stabilizing diode Z1, the current reaches a base electrode of the triode Q1 after passing through the first voltage-stabilizing diode Z1 and the fifth resistor R5, at the moment, a control end of the triode Q1 is started, the current flows to an emitter electrode of the triode Q1, starting current is provided for VCC of the constant current chip 1 through R4, after the starting, the current passes through the second inductor TL1A and generates electromotive force on the first inductor TL1B, and the current on the first inductor TL1B passes through the first diode D1, the third resistor R3, the triode Q1 and the fourth resistor R4 to provide working current for VCC, so that the LED lamp normally works.

When the power supply voltage is too low, the voltage cannot break down the first voltage stabilizing diode Z1, and the triode Q1 cannot be conducted, so that the constant current chip 1 has no starting current and cannot work, and the undervoltage protection is realized. Wherein the value of the under-voltage protection voltage is proportional to the voltage value of the first zener diode Z1.

When the power supply voltage is too high, the voltage reaches a certain high value, the second voltage-stabilizing diode Z2 is broken down, the current reaches the base electrode of the triode Q2 through the second voltage-stabilizing diode Z2 and the sixth resistor R6, the control end of the triode Q2 is opened at the moment, the current at the base electrode of the triode Q1 flows to the emitting electrode of the triode Q2, namely, the emitting electrode is connected with the ground, the triode Q1 is closed at the moment, no power supply current flows to the constant current chip 1, and overvoltage protection is realized. Wherein the voltage value of the overvoltage protection is proportional to the voltage value of the second zener diode Z2.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features. When technical features in different embodiments are represented in the same drawing, it can be seen that the drawing also discloses a combination of the embodiments concerned.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application.

Claims

1. The LED driving circuit with the protection function comprises a rectifying circuit, a filter circuit and a constant current circuit which are sequentially coupled, wherein the constant current circuit comprises a constant current chip which is coupled with the filter circuit through a power supply circuit.

2. The LED driving circuit according to claim 1, wherein the power supply circuit comprises a first resistor, a second resistor and a fourth resistor connected in series, and the first switching element is disposed between the second resistor and the fourth resistor.

3. The LED driving circuit according to claim 2, wherein the power supply circuit comprises a first inductor, a first diode and a third resistor connected in series in sequence, wherein the first inductor is grounded, and the third resistor is connected in series with the second resistor.

4. The LED driving circuit according to claim 1, wherein the under-voltage protection circuit comprises a first zener diode and a fifth resistor connected in series, the first zener diode is coupled to the filter circuit, and the fifth resistor is coupled to the control terminal of the first switching element.

5. The LED driving circuit according to claim 1, wherein the overvoltage protection circuit comprises a second switching element having a control terminal, and a second zener diode and a sixth resistor connected in series, the control terminal of the first switching element is grounded via the second switching element, the second zener diode is coupled to the filter circuit, and the sixth resistor is coupled to the control terminal of the second switching element.

6. The LED driving circuit according to claim 5, wherein the second switching element is a transistor Q2, and a base of a transistor Q2 is a control terminal thereof.

7. The LED driving circuit according to any of claims 1-6, wherein the first switching element is a transistor Q1, and the base of the transistor Q1 is the control terminal thereof.

8. The LED driving circuit according to claim 1, wherein the constant current circuit comprises an MOS transistor controlled by a constant current chip and an energy storage freewheeling unit.

9. The LED driving circuit according to claim 8, wherein the energy storage free-wheeling circuit comprises a second inductor and a second diode, and an anode of the second diode and the second inductor are coupled to a drain of the MOS transistor.

10. The LED driving circuit according to claim 1, wherein the filter circuit is an LC filter circuit.