CN216905379U

CN216905379U - LED drive circuit

Info

Publication number: CN216905379U
Application number: CN202121695298.4U
Authority: CN
Inventors: 刘拓夫; 翟向坤
Original assignee: On Bright Electronics Shanghai Co Ltd
Current assignee: On Bright Electronics Shanghai Co Ltd
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2022-07-05
Anticipated expiration: 2031-07-23
Also published as: TWM625902U

Abstract

The utility model provides an LED drive circuit. An LED drive circuit includes an input rectification circuit and a step-down control circuit, wherein: a first terminal of the input rectification circuit and a first terminal of the buck control circuit are connected together, a second terminal of the input rectification circuit and a second terminal of the buck control circuit are connected together, and an LED load is connected between the first terminal and a third terminal of the buck control circuit.

Description

LED drive circuit

Technical Field

The utility model relates to the field of circuits, in particular to an LED driving circuit.

Background

In some regions, there is a large fluctuation in the grid voltage during peak and valley of power consumption due to the instability of the grid voltage. If not controlled, the loss of the power device is greatly increased and the temperature is increased when the voltage of the power grid is too low or too high, which has an influence on the reliability of the whole system and is accompanied by a fire risk.

When the input voltage fluctuation range is wide, the conventional scheme often reduces the loss caused by too low input voltage by enlarging the used power device, which increases the cost of the whole system.

Therefore, a new solution is needed to solve the problem caused by the large fluctuation range of the input voltage.

SUMMERY OF THE UTILITY MODEL

In view of the above-described problems, the present invention provides a novel LED driving circuit.

According to an aspect of an embodiment of the present invention, there is provided an LED driving circuit including an input rectification circuit and a step-down control circuit, wherein: a first terminal of the input rectification circuit and a first terminal of the buck control circuit are connected together, a second terminal of the input rectification circuit and a second terminal of the buck control circuit are connected together, and an LED load is connected between the first terminal and a third terminal of the buck control circuit.

According to the LED driving circuit provided by the embodiment of the utility model, the output current can be automatically reduced according to the current power grid voltage under the condition that the input power grid voltage is too low, so that the purposes of reducing the system power and reducing the loss of a power device are achieved, the cost of the power device and the system is reduced, the system can stop working under the condition that the input power grid voltage is too high, and the reliability of the system is improved.

Drawings

The utility model may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which:

fig. 1 shows a circuit diagram of an LED driving circuit according to an embodiment of the present invention; and

fig. 2 shows a schematic diagram of a reference voltage and an input voltage of a control chip of an LED driving circuit according to an embodiment of the present invention.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below with reference to the accompanying drawings. Example implementations can be embodied in many forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art. In the drawings, the size of regions and components may be exaggerated for clarity. Further, in the drawings, the same reference numerals denote the same or similar structures, and thus detailed descriptions thereof will be omitted.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific configuration set forth below, but rather covers any modification, substitution, and improvement of elements and components without departing from the spirit of the utility model. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention. Note that the phrase "a and B are connected" as used herein may mean "a and B are directly connected" or "a and B are indirectly connected via one or more other elements".

Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Fig. 1 shows a circuit diagram of an LED driving circuit according to an embodiment of the present invention. As shown in fig. 1, the LED driving circuit according to the embodiment of the present invention includes an input rectification circuit 102 and a step-down control circuit 104, wherein: a first terminal of the input rectification circuit 102 and a first terminal of the step-down control circuit 104 are connected together, a second terminal of the input rectification circuit 102 and a second terminal of the step-down control circuit 104 are connected together, and the LED load 106 is connected between the first terminal and a third terminal of the step-down control circuit 104.

As shown in fig. 1, in some embodiments, the buck control circuit 104 includes a control chip U1, the control chip U1 includes an input voltage function select pin (i.e., LINE pin) and a chip high voltage supply pin (i.e., HV pin), wherein: the chip high voltage power pin (i.e., HV pin) serves as a first terminal of the step-down control circuit 104, the control chip U1 determines whether the low input voltage current foldback function is enabled and whether the high input voltage protection function is enabled based on the connection manner of the input voltage function selection pin (i.e., LINE pin), and the control chip U1 detects the input voltage of the LED driving circuit through the chip high voltage power pin (i.e., HV pin).

In some embodiments, the connection of the input voltage function selection pin (i.e., the LINE pin) includes ground, floating, etc., and the control chip U1 determines whether to enable the low input voltage current foldback function and whether to enable the high input voltage protection function based on the connection of the input voltage function selection pin (i.e., the LINE pin).

In some embodiments, the control chip U1 performs the following operations based on the input voltage of the LED driving circuit detected through the chip high voltage supply pin (i.e., HV pin): in the case where the low input voltage current foldback function is enabled, as shown in fig. 2, when the detected input voltage Vin is lower than the first voltage threshold V_{line_foldback}In the process, the reference voltage Vref inside the control chip U1 is controlled to be reduced along with the reduction of the input voltage Vin, so that the output current of the system is reduced along with the reduction of the input voltage Vin, and the purpose of reducing the loss of a power device is achieved. When the input voltage Vin is restored to the normal range, the reference voltage Vref inside the control chip U1 is restored to the normal value, and the output current of the system is also restored to the normal value; and in the case where the high input voltage protection function is enabled, as shown in fig. 2, when the detected input voltage Vin is higher than the second voltage threshold V_{line_OVP}In the meantime, the control chip U1 is controlled to stop working until the input voltage Vin is reduced to a normal range, thereby improving the reliability of the system.

As shown in fig. 1, in some embodiments, the control chip U1 further includes one or more of a chip reference ground pin (i.e., GND pin), an open protection detection pin (i.e., OVP pin), a current detection pin (i.e., CS pin), and an internal power transistor DRAIN pin (i.e., DRAIN pin).

As shown in FIG. 1, in some embodiments, the buck control circuit 104 further includes a current sense resistor R₂The current sense pin (i.e., the CS pin) is connected via a current sense resistor R₂To a second terminal of the buck control circuit 104.

When the LED driving circuit works, the chip high-voltage power supply pin (namely, HV pin) supplies power to the control chip U1, the control chip U1 samples current through the current detection pin (namely, CS pin), and controls the control chip U1 to enable the control chip U1 to work in a constant current state. The demagnetization detection and compensation loop of the system is completely integrated in the control chip U1, and high Power Factor (PF) and low current harmonic (THD) are realized.

As shown in fig. 1, in some embodiments, the buck control circuit 104 further includes an open-circuit protection detection resistor R₁The open protection detection pin (i.e., OVP pin) is connected to the second terminal of the buck control circuit 104 via an open protection detection pin resistor (i.e., OVP pin).

The open circuit protection detection resistor R connected with the open circuit protection detection pin (i.e. OVP pin) by the control chip U1₁To set the voltage for output over-voltage protection, the control chip U1 will turn on the output over-voltage protection when the output voltage exceeds the set voltage.

As shown in fig. 1, in some embodiments, a chip reference ground pin (i.e., GND pin) is connected to a second terminal of buck control circuit 104.

As shown in FIG. 1, in some embodiments, the buck control circuit 104 further includes a freewheeling diode D₅Power inductor L₁And an output filter capacitor C₂Freewheel diode D₅A power inductor L connected between the first terminal of the buck control circuit 104 and the DRAIN pin (i.e., DRAIN pin) of the internal power transistor₁Connected between the DRAIN pin (i.e., DRAIN pin) of the internal power transistor and the third terminal of the buck control circuit 104, and outputting a filter capacitor C₂Is connected between the first terminal and the third terminal of the buck control circuit 104.

As shown in FIG. 1, in some embodiments, the input rectification circuit 102 includesFuse F₁Rectifier bridge (comprising rectifier diode D)₁、D₂、D₃、D₄) And an input filter capacitor C₁. Here, the Alternating Current (AC) input to the rectification circuit 102 may be a normal AC input.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. An LED drive circuit, comprising an input rectification circuit and a voltage reduction control circuit, wherein:

a first terminal of the input rectification circuit and a first terminal of the step-down control circuit are connected together,

a second terminal of the input rectifying circuit and a second terminal of the step-down control circuit are connected together, and

an LED load is connected between the first terminal and the third terminal of the buck control circuit.

2. The LED driving circuit of claim 1, wherein the buck control circuit comprises a control chip including an input voltage function selection pin and a chip high voltage supply pin, wherein:

the chip high voltage supply pin serves as a first terminal of the buck control circuit,

the control chip judges whether to start the low input voltage current foldback function and whether to start the high input voltage protection function based on the connection mode of the input voltage function selection pin, and

the control chip detects the input voltage of the LED driving circuit through the chip high-voltage power supply pin.

3. The LED driving circuit according to claim 2, wherein the control chip further comprises one or more of a chip reference ground pin, an open protection detection pin, a current detection pin, and an internal power tube drain pin.

4. The LED drive circuit of claim 3 wherein the buck control circuit further comprises a current sense resistor, the current sense pin being connected to the second terminal of the buck control circuit via the current sense resistor.

5. The LED driver circuit of claim 3, wherein the buck control circuit further comprises an open protection detection resistor, the open protection detection pin being connected to the second terminal of the buck control circuit via the open protection detection pin resistor.

6. The LED driving circuit according to claim 2, wherein the chip reference pin is connected to the second terminal of the buck control circuit.

7. The LED driving circuit according to claim 3, wherein the buck control circuit further comprises a freewheeling diode connected between the chip high voltage supply pin and the internal power transistor drain pin, a power inductor connected between the internal power transistor drain pin and the third terminal of the buck control circuit, and an output filter capacitor connected between the first terminal and the third terminal of the buck control circuit.

8. The LED driving circuit according to claim 2, wherein the input voltage function selection pin is connected in a manner including ground and floating.

9. The LED driving circuit of claim 1, wherein the input rectifying circuit comprises a fuse, a rectifying diode, and an input filter capacitor.

10. The LED driving circuit according to claim 2, wherein the control chip performs the following operations based on the input voltage:

under the condition that the low input voltage and current foldback function is started, when the input voltage is lower than a first voltage threshold value, controlling the reference voltage inside the control chip to be reduced along with the reduction of the input voltage; and

and under the condition that the high input voltage protection function is enabled, when the input voltage is higher than a second voltage threshold value, controlling the control chip to stop working.