TWI808739B - Light source driver - Google Patents

Abstract

The invention discloses a light source driving device, which includes a first diode, a second diode and a driving chip. The first diode is coupled to the first dimming input end, and the second diode is coupled to the second dimming input end. The driving chip is coupled to the first diode, the second diode and the light source. The first diode and the second diode have the same specifications and are located in an isothermal environment. The first dimming input terminal and the second dimming input terminal receive the dimming voltage. The driving chip generates two equal fixed currents respectively passing through the first diode and the second diode, thereby generating a first driving voltage with the dimming voltage between the first diode and the driving chip, and generating a second driving voltage between the driving chip and the second diode, and the driving chip restores the dimming voltage and drives the light source according to the first driving voltage and the second driving voltage.

Description

Light source driver

The present invention relates to a driving device, and in particular to a light source driving device.

LED lighting has three main advantages, namely energy saving, environmental protection and green lighting. Because light-emitting diodes have high luminous efficiency and low production costs, their application prospects and markets are very broad, which makes light-emitting diodes one of the new generation of light sources that replace traditional light sources in the world today.

The dimming port of the current light-emitting diode driver, in order to prevent the high voltage from being wrongly connected, or when the dimming ports of multiple light-emitting diode drivers are connected in parallel, one of them will be damaged and all will be paralyzed, a diode 10 is connected to the positive input end of the dimming port, as shown in Figure 1. Although this measure is simple and low in cost, it brings two problems. Due to the voltage drop of the diode 10, the actual voltage between the positive and negative input terminals of the dimming port is different from the dimming voltage actually received by the LED driver. Currently, the conversion chip in the LED driver on the market cannot automatically eliminate the influence of the voltage drop on the diode 10. Some manufacturers do not consider the voltage drop on the diode 10 at all, while other manufacturers subtract 0.5 volts fixedly without considering the difference in voltage drop on the diode 10 of different types. In addition, since the diode is a nonlinear element. When the temperature changes, the voltage drop on the diode also changes, as shown in Figure 2, and it changes in a non-linear form, making the dimming voltage level between the positive and negative input terminals of the dimming port deviate more seriously than the brightness level output by the LED driver. In FIG. 2 , four different data correspond to four different forward bias voltages from top to bottom, which are 100, 10, 1 and 0.1 mA in sequence.

Therefore, the present invention proposes a light source driving device to solve the problems caused by the prior art.

The invention provides a light source driving device, which can truly restore the actual dimming voltage at different temperatures without changing the production cost, improves the detection accuracy of the dimming voltage, and improves the negative impact caused by the diode connected in series at the dimming input end.

To achieve the above purpose, the present invention provides a light source driving device, which is coupled to a light source. The light source driving device includes a first diode, a first driving chip, a second diode and a second driving chip. The cathode of the first diode is coupled to the first dimming input end, and the first driver chip is coupled to the anode of the first diode and the second dimming input end. The first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage, the first driver chip is used to generate a first fixed current through the first diode, and use the first fixed current and the dimming voltage to generate a first driving voltage at a first node between the first diode and the first driver chip. The cathode of the second diode is coupled to the ground, and the anode of the second diode is coupled to a constant current source. The fixed current source is used to generate a second fixed current through the second diode. The second fixed current is equal to the first fixed current. The first diode and the second diode have the same specifications and are located in an isothermal environment. The second fixed current generates a second driving voltage at a second node between the fixed current source and the second diode. The second driving chip is coupled to the light source, the first node and the second node. The second driving chip is used for receiving the first driving voltage and the second driving voltage, and driving the light source accordingly.

In an embodiment of the present invention, the light source driving device further includes a first filter circuit coupled between the first node and the second driver chip, and the second driver chip is used for receiving the first driving voltage through the first filter circuit.

In an embodiment of the present invention, the light source driving device further includes a second filter circuit coupled between the second node and the second driving chip, and the second driving chip is used for receiving the second driving voltage through the second filter circuit.

In one embodiment of the present invention, the first diode and the second diode are located at the same on a printed circuit board.

In an embodiment of the present invention, the fixed current source includes a fixed voltage source and a resistor, the resistor is coupled between the fixed voltage source and the second node, and the fixed voltage source is used to generate a second fixed current through the resistor.

In one embodiment of the present invention, the light source is a light emitting diode.

In an embodiment of the present invention, a light source driving device is coupled to a light source, and the light source driving device includes a first diode, a second diode and a driving chip. The cathode of the first diode is coupled to the first dimming input end, and the cathode of the second diode is coupled to the second dimming input end. The first diode and the second diode have the same specifications and are located in an isothermal environment. The first dimming input terminal and the second dimming input terminal are used for receiving a dimming voltage. The driving chip is coupled to the anodes of the first diode and the second diode and the light source. The driving chip is used to generate a first fixed current and a second fixed current respectively passing through the first diode and the second diode, and the second fixed current is equal to the first fixed current. The driving chip is used to generate a first driving voltage at the first node between the first diode and the driving chip by using the first fixed current and the dimming voltage, and the second fixed current generates a second driving voltage at the second node between the driving chip and the second diode. The driving chip is used to receive the first driving voltage and the second driving voltage, and drive the light source accordingly.

In an embodiment of the present invention, the light source driving device further includes a filter circuit coupled between the first node and the driving chip, and the driving chip is used for receiving the first driving voltage through the filter circuit.

In one embodiment of the present invention, the first diode and the second diode are located on the same printed circuit board.

In one embodiment of the present invention, the light source is a light emitting diode.

Based on the above, the light source driving device sets a diode and the diode connected to the dimming input terminal in an isothermal environment, and at the same time designs the first diode and the second diode to have the same specifications, and obtains the forward bias of the second diode under the premise that the same current passes through the first diode and the second diode. In this way, the actual dimming voltage can be truly restored at different temperatures without changing the production cost, the detection accuracy of the dimming voltage is improved, and the negative impact caused by the diode connected in series at the dimming input end is improved.

In order to make your review committee members have a further understanding and understanding of the structural features and the achieved effects of the present invention, I would like to provide a better embodiment diagram and a detailed description, as follows:

10: Diode

2: Light source driving device

20: The first diode

21: The first driver chip

22: Second diode

23: The second driver chip

24: Fixed current source

240: Resistor

25: The first dimming input terminal

26: Second dimming input terminal

27: The first filter circuit

28: Second filter circuit

3: light source

4: Light source driving device

40: The first diode

41: Second diode

42: Driver chip

43: The first dimming input terminal

44: Second dimming input terminal

45: filter circuit

5: light source

N1: the first node

N2: second node

VD: dimming voltage

I1: the first fixed current

I2: the second fixed current

V1: the first driving voltage

V2: Second driving voltage

VCC, VDD: fixed voltage source

FIG. 1 is a schematic diagram of a light emitting diode driver in the prior art.

FIG. 2 is a graph of the junction temperature and forward bias voltage of the light-emitting diode of the prior art.

Fig. 3 is a schematic diagram of the first embodiment of the light source driving device of the present invention.

Fig. 4 is a schematic diagram of the second embodiment of the light source driving device of the present invention.

Fig. 5 is a schematic diagram of the third embodiment of the light source driving device of the present invention.

Embodiments of the present invention will be further explained in conjunction with related figures below. Wherever possible, the same reference numerals have been used throughout the drawings and description to refer to the same or similar components. In the drawings, the shape and thickness may be exaggerated for the sake of simplification and convenient labeling. It should be understood that elements not particularly shown in the drawings or described in the specification are forms known to those skilled in the art. Those skilled in the art can make various changes and modifications according to the content of the present invention.

When an element is referred to as being "on", it may generally mean that the element is directly on other elements, or there may be other elements present in between. Conversely, when an element is referred to as being "directly on" another element, it cannot have the other element in between. As used herein, the word "and/or" includes any combination of one or more of the associated listed items.

The following description about "one embodiment" or "an embodiment" refers to at least A particular element, structure or feature associated within an embodiment. Therefore, multiple descriptions of "one embodiment" or "an embodiment" appearing in various places below do not refer to the same embodiment. Furthermore, specific components, structures and features in one or more embodiments may be combined in an appropriate manner.

The disclosure is particularly described with the following examples, which are only used for illustration, because for those skilled in the art, various changes and modifications can be made without departing from the spirit and scope of the disclosure, so the protection scope of the disclosure should be defined by the scope of the appended patent application. Throughout the specification and claims, the meanings of "a" and "the" include that such description includes "one or at least one" of the element or component, unless the content clearly specifies otherwise. Furthermore, as used in the present disclosure, singular articles also include descriptions of plural elements or components, unless it is obvious from the specific context that the plural is excluded. Also, as applied in this description and all claims below, the meaning of "in" may include "in" and "on" unless the content clearly dictates otherwise. The terms (terms) used throughout the specification and patent claims generally have the ordinary meaning of each term used in this field, in the content of this disclosure and in the specific content, unless otherwise specified. Certain terms used to describe the disclosure are discussed below or elsewhere in this specification to provide practitioners with additional guidance in describing the disclosure. The use of examples anywhere throughout the specification, including examples of any terms discussed herein, is for illustration only and certainly does not limit the scope and meaning of the disclosure or any exemplified terms. Likewise, the present disclosure is not limited to the various embodiments presented in this specification.

It can be understood that the terms "comprising", "including", "having", "containing", "involving", etc. as used herein are open-ended, meaning including but not limited to. In addition, any embodiment or scope of claims of the present invention does not necessarily achieve all the objectives or advantages or features disclosed in the present invention. In addition, the abstract and title are only used to assist in the search of patent documents, and are not used to limit the scope of patent applications for inventions.

Unless otherwise specified, some conditional sentences or words, such as "can (can)", "could (could)", "maybe (might)", or "may (may)", are generally intended to express that the embodiment of the present case has, but can also be interpreted as a feature, element, or step that may not be required. In other embodiments, these features, elements, or steps may not be required.

The following will describe a light source driving device, which sets a diode and the diode connected to the dimming input terminal in an isothermal environment, and at the same time designs the first diode and the second diode to have the same specifications, and obtains the forward bias voltage of the second diode under the premise that the same current passes through the first diode and the second diode. In this way, the actual dimming voltage can be truly restored at different temperatures without changing the production cost, and the detection accuracy of the dimming voltage is improved. affect.

Fig. 3 is a schematic diagram of the first embodiment of the light source driving device of the present invention. Please refer to FIG. 3 , the first embodiment of the light source driving device 2 is introduced below. The light source driving device 2 is coupled to a light source 3, and the light source 3 is an example of a light emitting diode, but the present invention is not limited thereto. The light source driving device 2 includes a first diode 20 , a first driver chip 21 , a second diode 22 , a second driver chip 23 , a constant current source 24 , a first dimming input 25 and a second dimming input 26 . The cathode of the first diode 20 is coupled to the first dimming input terminal 25 , the first driver chip 21 is coupled to the fixed voltage source VCC, the anode of the first diode 20 and the second dimming input terminal 26 . The cathode of the second diode 22 is coupled to the ground, and the anode of the second diode 22 is coupled to the fixed current source 24 . The second driving chip 23 is coupled to the fixed voltage source VDD, the light source 3 , the first node N1 between the first diode 20 and the first driving chip 21 , and the second node N2 between the fixed current source 24 and the second diode 22 . The first diode 20 and the second diode 22 have the same specifications, for example, the same size and doping concentration of semiconductor carriers, and the first diode 20 and the second diode 22 are located in an isothermal environment. For example, the first diode 20 and the second diode 22 can be located on the same printed circuit board, and the distance between them is less than 5 cm. In this way, when the temperature changes, the first two The voltage drop across the polar body 20 and the second diode 22 also changes in the same way. That is to say, no matter how the temperature changes, the temperature received by the first diode 20 and the second diode 22 is the same. If the current passing through the first diode 20 and the second diode 22 is designed to be the same, it means that the forward bias voltage of the first diode 20 and the second diode 22 is also the same.

The operation process of the first embodiment of the light source driving device 2 is introduced below. The first dimming input terminal 25 and the second dimming input terminal 26 receive a dimming voltage VD, the first driver chip 21 generates a first fixed current I1 passing through the first diode 20, and uses the first fixed current I1 and the dimming voltage VD to generate a first driving voltage V1 at a first node N1 between the first diode 20 and the first driver chip 21. The fixed current source 24 generates a second fixed current I2 passing through the second diode 22, and the second fixed current I2 is designed to be equal to the first fixed current I1, so that the forward bias voltages of the first diode 20 and the second diode 22 are the same. The second fixed current I2 generates a second driving voltage V2 at the second node N2 between the fixed current source 24 and the second diode 22 . The second driving chip 23 receives the first driving voltage V1 and the second driving voltage V2, and drives the light source 3 accordingly. Since the first driving voltage V1 is equal to the forward bias voltage of the first diode 20 plus the dimming voltage VD, and the forward bias voltages of the first diode 20 and the second diode 22 are the same, the second driving chip 23 can subtract the second driving voltage V2 from the first driving voltage V1 to truly restore the dimming voltage VD at any temperature without changing the manufacturing cost, improve the detection accuracy of the dimming voltage VD, and improve the negative impact caused by the series connection of diodes at the dimming input.

In order to improve the accuracy of the first driving voltage V1 and the second driving voltage V2, in some embodiments of the present invention, the light source driving device 2 may further include a first filter circuit 27 and a second filter circuit 28 . The first filter circuit 27 is coupled between the first node N1 and the second driver chip 23 , and the second driver chip 23 receives the first driving voltage V1 through the first filter circuit 27 . The second filter circuit 28 is coupled between the second node N2 and the second driver chip 23 , and the second driver chip 23 receives the second driving voltage V2 through the second filter circuit 28 . Furthermore, in specific In the present circuit, the fixed current source 24 may include a fixed voltage source VDD and a resistor 240 . The resistor 240 is coupled between the fixed voltage source VDD and the second node N2 , and the fixed voltage source VDD generates a second fixed current I2 passing through the resistor 240 .

Fig. 4 is a schematic diagram of the second embodiment of the light source driving device of the present invention. Please refer to FIG. 4 , the second embodiment of the light source driving device 4 is introduced below. The light source driving device 4 is coupled to a light source 5, and the light source 5 is an example of a light emitting diode, but the present invention is not limited thereto. The light source driving device 4 includes a first diode 40 , a second diode 41 , a driving chip 42 , a first dimming input 43 and a second dimming input 44 , wherein the second dimming input 44 is coupled to the ground. The cathode of the first diode 40 is coupled to the first dimming input terminal 43 , and the cathode of the second diode 41 is coupled to the second dimming input terminal 44 . The first diode 40 and the second diode 41 have the same specifications, such as the same size and doping concentration of semiconductor carriers, and the first diode 40 and the second diode 41 are located in an isothermal environment. For example, the first diode 40 and the second diode 41 can be located on the same printed circuit board, and the distance between them is less than 5 cm. In this way, when the temperature changes, the voltage drops on the first diode 40 and the second diode 41 also change in the same way. That is to say, no matter how the temperature changes, the temperature received by the first diode 40 and the second diode 41 is the same. If the current passing through the first diode 40 and the second diode 41 is designed to be the same, it means that the forward bias voltage of the first diode 40 and the second diode 41 is also the same. The driving chip 42 is coupled to the anodes of the first diode 40 and the second diode 41 and the light source 5 .

The operation process of the second embodiment of the light source driving device 4 is introduced below. The first dimming input terminal 43 and the second dimming input terminal 44 receive a dimming voltage VD, and the driving chip 42 generates a first fixed current I1 and a second fixed current I2 passing through the first diode 40 and the second diode 41 respectively, and the second fixed current I2 is designed to be equal to the first fixed current I1, so that the forward bias voltages of the first diode 40 and the second diode 41 are the same. The driver chip 42 uses the first fixed current I1 and the dimming voltage VD to generate the first driving voltage V1 at the first node N1 between the first diode 40 and the driver chip 42, and the second fixed current I2 The second driving voltage V2 is generated at the second node N2 between the driving chip 42 and the second diode 41 . The driving chip 42 receives the first driving voltage V1 and the second driving voltage V2, and drives the light source 5 accordingly. Since the first driving voltage V1 is equal to the forward bias voltage of the first diode 40 plus the dimming voltage VD, and the forward bias voltages of the first diode 40 and the second diode 41 are the same, the driver chip 42 can restore the dimming voltage VD at any temperature by subtracting the second driving voltage V2 from the first driving voltage V1, without changing the manufacturing cost, improving the detection accuracy of the dimming voltage VD, and reducing the negative impact caused by the series connection of diodes at the dimming input.

In order to improve the accuracy of the first driving voltage V1, in some embodiments of the present invention, the light source driving device 4 may further include a filter circuit 45, which is coupled between the first node N1 and the driving chip 42, and the driving chip 42 receives the first driving voltage V1 through the filtering circuit 45.

Fig. 5 is a schematic diagram of the third embodiment of the light source driving device of the present invention. The difference between the third embodiment and the second embodiment is that the filter circuit 45 of the third embodiment is integrated in the driving chip 42 and coupled to the first node N1 to reduce circuit complexity. The driving chip 42 receives the first driving voltage V1 through the filter circuit 45 .

According to the above-mentioned embodiment, the light source driving device sets the second diode and the first diode connected to the dimming input terminal in an isothermal environment, and at the same time, the first diode and the second diode are designed to have the same specifications, and the forward bias voltage of the second diode is obtained under the premise that the same current passes through the first diode and the second diode. In this way, the actual dimming voltage can be restored at different temperatures without changing the production cost, improving the detection accuracy of the dimming voltage, and improving the negative effects caused by the series connection of diodes at the dimming input terminal. affect.

The above is only a preferred embodiment of the present invention, and is not used to limit the scope of the present invention. Therefore, all equal changes and modifications made according to the shape, structure, characteristics and spirit described in the scope of the patent application of the present invention should be included in the scope of the patent application of the present invention.

2: Light source driving device

20: The first diode

21: The first driver chip

22: Second diode

23: The second driver chip

24: Fixed current source

240: Resistor

25: The first dimming input terminal

26: Second dimming input terminal

27: The first filter circuit

28: Second filter circuit

3: light source

N1: the first node

N2: second node

VD: dimming voltage

I1: the first fixed current

I2: the second fixed current

V1: the first driving voltage

V2: Second driving voltage

VCC, VDD: fixed voltage source

Claims (10)

A light source driving device, coupled to a light source, the light source driving device includes: a first diode, the cathode of which is coupled to the first dimming input terminal; A first driving chip, coupled to the anode of the first diode and the second dimming input terminal, wherein the first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage, the first driving chip is used to generate a first fixed current passing through the first diode, and use the first fixed current and the dimming voltage to generate a first driving voltage at a first node between the first diode and the first driving chip; a second diode, the cathode of which is coupled to the ground terminal, and the anode is coupled to a fixed current source, wherein the fixed current source is used to generate a second fixed current through the second diode, the second fixed current is equal to the first fixed current, the first diode and the second diode have the same specification, and are located in an isothermal environment, and the second fixed current generates a second driving voltage at a second node between the fixed current source and the second diode; and A second driving chip is coupled to the light source, the first node and the second node, wherein the second driving chip is used for receiving the first driving voltage and the second driving voltage, and driving the light source accordingly. The light source driving device according to claim 1 further includes a first filter circuit coupled between the first node and the second driver chip, and the second driver chip is configured to receive the first driving voltage through the first filter circuit. The light source driving device according to claim 2 further includes a second filter circuit coupled between the second node and the second driver chip, and the second driver chip is configured to receive the second drive voltage through the second filter circuit. The light source driving device according to claim 1, wherein the first diode and the second diode are located on the same printed circuit board. The light source driving device as described in Claim 1, wherein the fixed current source includes: a fixed voltage source; and A resistor is coupled between the fixed voltage source and the second node, wherein the fixed voltage source is used to generate the second fixed current through the resistor. The light source driving device according to claim 1, wherein the light source is a light emitting diode. A light source driving device, coupled to a light source, the light source driving device includes: a first diode, the cathode of which is coupled to the first dimming input terminal; a second diode, the cathode of which is coupled to the second dimming input terminal, wherein the first diode and the second diode have the same specification and are located in an isothermal environment, the first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage; and A driving chip, coupled to the anodes of the first diode and the second diode and the light source, wherein the driving chip is used to generate a first fixed current and a second fixed current passing through the first diode and the second diode respectively, the second fixed current is equal to the first fixed current, the driving chip is used to generate a first driving voltage at a first node between the first diode and the driving chip using the first fixed current and the dimming voltage, and the second fixed current is used to generate a second driving voltage at a second node between the driving chip and the second diode. The chip is used for receiving the first driving voltage and the second driving voltage, and driving the light source accordingly. The light source driving device as claimed in Claim 7 further includes a filter circuit coupled between the first node and the driver chip, and the driver chip is configured to receive the first driving voltage through the filter circuit. The light source driving device according to claim 7, wherein the first diode and the second diode are located on the same printed circuit board. The light source driving device according to claim 7, wherein the light source is a light emitting diode.

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