KR102103266B1 - An LED driving circuit capable of multi-channel constant power constant current driving - Google Patents

Abstract

The present invention relates to an LED driving circuit capable of multi-channel constant power-constant current driving so as to enable a multi-channel constant power-constant current driving in the LED driving circuit, such as automotive lighting, which has a high input voltage and requires driving stability or high reliability such as reliability on a circuit temperature. To this end, the present invention in the LED driving circuit for driving a plurality of LEDs with constant current includes: a multi-channel constant power-constant current driving circuit connected to voltage input terminals of the plurality of LEDs and each driving channel and configured to control the constant current of each driving channel of the LED driving circuit to maintain the same constant power as when the maximum number of LEDs is turned on even in a low input voltage range, so that problems on output current stability and heat generation are solved in an entire input voltage range, thereby ensuring high reliability, and total sizes and costs of the implemented circuit are reduced, thereby reducing overall costs.

Description

An LED driving circuit capable of multi-channel constant power constant current driving}

The present invention relates to an LED driving circuit, and more specifically, a multi-channel constant power-constant current driving is possible in an LED driving circuit that has a wide input voltage and requires high reliability such as driving stability or reliability for circuit temperature, such as automotive lighting. The present invention relates to an LED driving circuit capable of driving a multi-channel constant power-constant current that can secure high reliability and reduce overall cost by reducing the total size and cost of the implemented circuit.

In general, the conventional LED driving method used for automobile lighting can be roughly divided into two types.

The first method is a switching driving method as illustrated in FIG. 1, and implements efficiency and high reliability (driving stability, circuit temperature stability, etc.) using a field effect transistor (FET), diode, inductor, etc. This is possible.

However, such a conventional switching driving method has a problem of electromagnetic interference due to switching driving, and the volume of required components is large, thereby increasing the total size of the implementation circuit and increasing the cost, which is not used well.

The second method is a constant current driving method called a linear driving method as illustrated in FIGS. 2A and 2B, and a bulky and expensive device such as a field effect transistor (FET), a diode, an inductor, etc. By using no components, there is no electromagnetic interference (EMI) problem and a circuit smaller than the switching driving method can be implemented.

However, this linear driving method has disadvantages in that the driving stability is poor depending on the input voltage range and the reliability of the circuit temperature is low.

Specifically, in the linear driving method as described above, in the region of the entire input voltage Vin 7V to 27V, which is the driving region of the general automobile lighting, a region in which constant current driving is not performed according to the quantity of LEDs occurs. For example, in the case of the constant current driving circuit as shown in FIG. 2B using a typical 3Vf LED 3EA, since the constant current driving is usually performed at 9V or higher, there is a problem that the normal constant current driving is not performed in the low voltage region 7V to 9V. However, the constant current driving circuit as shown in FIG. 2A using a typical 3Vf LED 2EA is a normal constant current driving in the low voltage region 7V to 9V, but a reliability problem occurs due to the heating problem of the constant current driving circuit when the input voltage is higher than 20V (depending on conditions). Occurs. Here, although the constant current driving circuit using the 3Vf LED 3EA shown in FIG. 2B has a heat generation problem, it means that it generates less heat than the constant current driving circuit using the 3Vf LED 2EA shown in FIG. 2A.

As described above, the constant current driving method has the advantage of having a smaller size and a lower cost of the constant current driving circuit than the switching driving method, but in common, a heat generation problem occurs, which is smaller than the switching driving method, but there is a problem in that the size of the constant current driving circuit needs to be increased. The cost of the constant current driving circuit increases.

KR 10-2013-0045056 A 2013.05.03 released KR 10-2013-0071776 A 2013.07.01 released

Therefore, the present invention has been devised to solve the above-mentioned disadvantages, and the technical problem to be solved by the present invention is an LED driving assembly in which input voltage is wide and high reliability such as driving stability or reliability for circuit temperature is required, such as automobile lighting. By enabling multi-channel constant power-constant current driving in the furnace, it is possible to secure high reliability by solving the output current stability and heat generation problem in the entire input voltage range, and reduce the total cost by reducing the total size and cost of the implemented circuit. It is to provide an LED driving circuit capable of driving a multi-channel constant power-constant current.

One embodiment of the present invention for achieving the above object, in the LED driving circuit for driving a plurality of LEDs in a constant current, the voltage input terminal of the plurality of LEDs and each drive channel is connected to each drive channel, the maximum number of Multi-channel constant-power-constant current-driven LED driving circuit including multi-channel constant-power-constant-current driving circuit that controls the constant current of each driving channel of the LED driving circuit so as to maintain the same LED brightness (constant power) when the LED is lit to be.

In one embodiment of the present invention, the multi-channel constant power-constant current driving circuit can be implemented by controlling the constant current of each driving channel according to the voltage of each driving channel of the LED driving circuit.

According to the present invention, it is possible to solve the problem of output current stability and heat generation in the entire input voltage range, minimize the size of the constant current driving circuit, minimize the total area of the circuit, and can also be implemented at the minimum cost. It provides the advantage of being able to save money.

1 is a conventional switching driving circuit diagram.
2A and 2B are a conventional LED 2EA driving circuit diagram and an LED 3EA driving circuit diagram, respectively.
3 is a diagram illustrating a state in which the multi-channel constant power-constant current driving circuit according to the present invention is applied to a circuit for driving three LEDs.
4 is a detailed block diagram of a multi-channel constant power-constant current driving circuit according to the present invention.
5 is a reference diagram illustrating current / voltage for each driving channel (per channel) in the multi-channel constant power-constant current driving circuit according to the present invention.
6 (a) and 6 (b) are graphs illustrating the current shape according to the voltage rise and the voltage drop of each drive channel in the multi-channel constant power-constant current driving circuit according to the present invention, respectively.
7A and 7B are diagrams illustrating a state in which the multi-channel constant power-constant current driving circuit according to the present invention is applied to circuits driving two LEDs and circuits driving one LED, respectively.

Hereinafter, the configuration and operation of the multi-channel constant power-constant current driving circuit according to the preferred embodiment of the present invention and the effects of the operation will be described in detail with reference to the accompanying drawings.

The terms or words used in the specification and claims are not to be construed as being limited to ordinary or lexical meanings, and the inventor is based on the principle that the concept of terms can be properly defined in order to best describe his or her invention. It should be interpreted in a sense and concept consistent with the technical idea of the present invention. Therefore, since the embodiments illustrated in the specification and the drawings illustrated in the specification are only the most preferred embodiments of the present invention, it is understood that there may be various equivalents and modifications that can replace them at the time of application. shall.

3 is a diagram illustrating a state in which the multi-channel constant power-constant current driving circuit according to the present invention is applied to a circuit for driving three LEDs, and FIG. 4 is a detailed block of the multi-channel constant power-constant current driving circuit according to the present invention As shown in the figure, the LED driving circuit capable of driving a multi-channel constant power-constant current according to the present invention includes, as illustrated in FIG. 3, a plurality of LEDs connected in series (LED1-LED3) and the plurality of LEDs (LED1-LED3). It comprises a multi-channel constant-power-constant-current driving circuit 100 connected between the voltage input terminal (Vin) and each driving channel terminal, such a multi-channel constant-power-driven LED driving circuit capable of driving is automotive It can be applied to LED driving circuits, such as lighting, which have a wide input voltage range and require high reliability. Here, the plurality of LEDs (LED1-LED3) may be configured in series as illustrated in FIG. 3, but may be configured in parallel or may be configured together in series and parallel, and in the following detailed description of the present invention, 3 The configuration in which the LEDs are connected in series will be described as an example.

The multi-channel constant power-constant current driving circuit 100 is connected to the voltage input terminal (Vin) of each LED (LED1-LED3) and each driving channel terminal, and has the same LED brightness when the maximum number of LEDs is lit even in the low input voltage range. The constant current of each driving channel of the LED driving circuit is controlled to maintain (constant power). The multi-channel constant power-constant current driving circuit 100 controls the constant current (I1 / I2 / I3 / I4) of each driving channel according to the terminal voltage (V1 / V2 / V3 / V4) of each driving channel of the LED driving circuit. Can be implemented. To this end, the multi-channel constant power-constant current driving circuit 100 of the present invention includes a driving circuit power generation circuit section 110, a driving channel voltage sensing and channel selection driving circuit section 120, and a channel, as illustrated in FIG. 4. It may be configured to include a constant current driving circuit 130 according to. In addition, the multi-channel constant power-constant current driving circuit 100 of the present invention may be implemented in different embodiments by further including a driving circuit temperature sensing and channel change signal generation circuit unit 140 and / or a temperature protection circuit unit 150. It might be.

The driving circuit power generation circuit unit 110 is connected to the voltage input terminal Vin of the LED driving circuit to generate and supply the power of the LED driving circuit.

The driving channel voltage detection and channel selection driving circuit unit 120 includes a plurality of fixed terminals respectively connected to each driving channel terminal of the LED driving circuit, and one switching terminal connected to the constant current driving circuit unit 130 according to the channel. It includes a drive channel selection switch for connecting the switching terminal to any one of a plurality of fixed terminals, and detects the voltage for each drive channel of the LED drive circuit or senses the temperature of the drive circuit and generates the channel change signal generation circuit 140 Received, and receives the channel change signal to be transmitted, controls the operation of the switching terminal by the channel change signal or the result of sensing the voltage of each drive channel, and controls any one of the drive channels of the LED drive circuit to the constant current drive circuit unit 130 according to the channel. Connect.

The constant current driving circuit unit 130 according to the channel supplies a constant current according to each driving channel to each driving channel of the LED driving circuit.

The drive circuit temperature detection and channel change signal generation circuit unit 140 sets a plurality of drive channel switching temperature values TCsw for changing the drive channel of the LED drive circuit, and detects the temperature of the LED drive circuit to switch for each drive channel According to the temperature value, a channel change signal for changing each drive channel is generated and transmitted to the drive channel voltage detection and channel selection drive circuit unit 120.

The temperature protection circuit unit 150 sets a shutdown temperature value TS for shutdown of the constant current driving circuit unit 130 according to a channel, detects the heating temperature of the LED driving circuit, and detects a predetermined shutdown temperature value, depending on the channel. The constant current driving circuit 130 is shut down to maintain temperature stability against heat generation of the constant current driving circuit 130 according to the channel.

The operation of the LED driving circuit capable of driving the multi-channel constant power-constant current according to the present invention configured as described above and the effect of the operation are as follows.

5 is a reference diagram illustrating current / voltage for each point (per channel) illustrated to illustrate the operation of the multi-channel constant power-constant current driving circuit according to the present invention, and FIGS. 6 (a) and (b) are In the multi-channel constant-power-constant-current driving circuit of FIG. 5, a graph illustrating the current form according to the voltage rise and the current form according to the voltage drop of each driving channel Ch1-Ch4 set in the constant-current driving circuit part according to the channel, according to the present invention The multi-channel constant power-constant current driving circuit is connected to the voltage input terminal (Vin) of each LED (LED1-LED3) and each driving channel terminal and maintains the same constant power when the maximum number of LEDs is turned on even in the low input voltage range. Thus, since it is possible to control the constant current of each driving channel of the LED driving circuit, even when using a typical 3Vf LED 3EA [dog] as illustrated in FIG. 5, a plurality of LEDs (LED1) even in a low input voltage region (7V to 9V) It is possible to realize the same power (light amount) as when ~ LED3) is all turned on, and the heat generation problem does not appear even in the general input voltage range of 7V to 27V, and the size and cost of the implementation circuit can be realized. The multi-channel constant voltage-constant current driving circuit of the present invention is a current (I1 / I2 / I3 /) for each point according to the voltage (V1 / V2 / V3 / V4) of each point (per drive channel) terminal illustrated in FIG. I4) can be implemented by controlling.

That is, FIG. 6 (a) illustrates the current form of each driving channel Ch1-Ch4 by the constant current driving circuit 130 according to the channel when the input voltage rises, and VR1 in which the voltage of V1 is set in the circuit of FIG. The initial driving channel Ch1 is opened by the driving channel voltage sensing and channel selection driving circuit unit 120 before reaching the voltage of, and the initial driving channel Ch1 is driven by a constant current according to the channel as illustrated in FIG. 6 (a). It is controlled by the I1 current set by the circuit unit 130.

Thereafter, when the voltage of V1 in the circuit of FIG. 5 reaches the set voltage of VR1, the initial driving channel Ch1 is closed and the second driving channel Ch2 is opened by the driving channel voltage sensing and channel selection driving circuit 120. The driving channel Ch2 is controlled by the I2 current set by the constant current driving circuit 130 according to the channel as illustrated in FIG. 6 (a). Here, the current I2 flowing in the second driving channel is set to have a lower value than the current I1 of the initial driving channel. In the multi-channel constant power-constant current driving circuit according to the present invention, it is preferable to implement a current I2 set to realize the same power as when two LEDs are turned on by lowering the current flowing in the corresponding channel when driving three LEDs as described above. Do. Accordingly, it is possible to realize the same power (light amount) regardless of the number of LEDs in the general input voltage 7V to 12V range. This makes it possible to drive three LEDs having high temperature stability not only in the stability of power (light amount) but also in the high input voltage range (ex 20V or more) in the future.

In addition, the second driving channel Ch2 is closed and the third driving channel Ch3 is closed by the driving channel voltage sensing and channel selection driving circuit 120 when the input voltage is continuously increased in the circuit of FIG. 5 and the voltage of V2 reaches the set VR2 voltage. Is opened, the third driving channel Ch3 is controlled by the current I3 set by the constant current driving circuit 130 according to the channel as illustrated in FIG. 6 (a). Here, the current I3 of the third driving channel is the same as the current I2 of the second driving channel. This prevents deterioration of circuit stability due to occurrence of heat generation of the constant current driving circuit as the input voltage rises, and at the same time, it is possible to maintain the same power (light amount) of the three LEDs.

In addition, when the voltage of V3 reaches the set VR3 voltage continuously in the circuit of FIG. 5, the third driving channel Ch3 is closed and the fourth driving channel Ch4 is closed by the driving channel voltage sensing and channel selection driving circuit unit 120. Is opened, and the fourth driving channel Ch4 is controlled by the current I4 set by the constant current driving circuit 130 according to the channel as illustrated in FIG. 6 (a). Here, the current I4 of the fourth driving channel is the same as the current I3 of the third driving channel. If the heat dissipation design is good, the stability of the entire constant current driving circuit may be realized by driving only the third driving channel Ch3.

FIG. 6 (b) illustrates the current form flowing through each of the driving channels Ch1-Ch4 by the constant current driving circuit according to the channel when the input voltage falls, and has a constant hysteresis as compared with the case where the voltage rises in FIG. 6 (a). It has a (hysteresis) and illustrates that it is set to move in contrast to FIG. 6 (a).

In addition, another feature of the present invention is a driving circuit voltage sensing and channel selection driving circuit unit 120, as illustrated in FIG. 4, further comprising a driving circuit temperature sensing and channel change signal generation circuit unit 140 to detect the driving circuit temperature. And a channel change signal generating circuit unit 140 to control the switching operation for sensing the driving channel voltage and selecting the channel of the channel selection driving circuit unit 120, thereby controlling the channel driving method using the own temperature sensing circuit of the constant current driving circuit. It is to enable stable constant current driving. This method makes it possible to provide a method for maintaining temperature stability even when constant current circuit heat generation due to abnormal heat generation according to the internal / external environment occurs before the operation by the set voltage sensing.

The multi-channel constant power-constant current driving circuit 100 according to the present invention maintains the same power (light amount) even when changing the channel using the driving circuit temperature sensing and channel changing signal generation circuit unit 140. It is a feature that, if a condition in which the same power (light quantity) cannot be maintained (ex drive voltage margin is insufficient) occurs, the entire temperature protection circuit unit (Thermal shutdown: 150) is operated without changing the channel.

In addition, the multi-channel constant power-constant current driving circuit 100 according to the present invention includes a driving channel voltage sensing and channel selection driving circuit 120 and a driving circuit temperature sensing and channel change signal generation circuit 140 as illustrated in FIG. 4. The method using or may be used individually or in combination.

7A and 7B are diagrams illustrating a state in which the multi-channel constant power-constant current driving circuit according to the present invention is applied to a circuit driving two LEDs and a circuit driving one LED, respectively. The multi-channel constant power-constant current driving circuit according to the present invention detects the above driving channel voltage and selects the driving circuit 120 regardless of the number of LEDs as illustrated in FIGS. 7 (a) and 7 (b). And it is possible to implement the same constant power (same brightness) and constant current using the driving circuit temperature sensing and channel change signal generation circuit unit 140.

According to the LED driving circuit capable of driving the multi-channel constant power-constant current of the present invention as described above, while solving the problem of output current stability and heat generation in the entire input voltage range, the size of the constant current driving circuit can be minimized and is also minimal. It is possible to implement at the cost of, so that the overall implementation cost can be reduced.

As described above, although the present invention has been described with limited embodiments and drawings, the present invention is not limited to the above embodiments, and various modifications and modifications can be made from these descriptions to those skilled in the art to which the present invention pertains. Deformation is possible. Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalents or equivalent modifications thereof will be said to be within the scope of the spirit of the present invention.

100: multi-channel constant power-constant current driving circuit
110: driving circuit power generation circuit
120: driving channel voltage detection and channel selection driving circuit
130: constant current driving circuit according to the channel
140: circuit for detecting the driving circuit temperature and generating a channel change signal
150: temperature protection circuit

Claims (6)

In the automotive LED driving circuit for driving a plurality of LEDs (LED1-LED3) constant current,
The voltage input terminal (Vin) of the plurality of LEDs (LED1-LED3) and connected to each driving channel sense the temperature of the LED driving circuit, and the same LED brightness (constant power) when the maximum number of LEDs is lit even in the low input voltage range Multi-channel constant power-constant current driving circuit for controlling the constant current of each driving channel of the LED driving circuit to maintain the; According to claim 1, The multi-channel constant power-constant current driving circuit 100,
Multi-channel constant power-constant current driving characterized in that the constant current (I1 / I2 / I3 / I4) of each driving channel is controlled according to the terminal voltage (V1 / V2 / V3 / V4) of each driving channel of the LED driving circuit This possible LED driving circuit. The method of claim 1, wherein the plurality of LEDs (LED1-LED3),
Multi-channel constant-power-constant current-driven LED driving circuit, characterized in that it is configured in series or parallel or a combination of series and parallel. According to claim 1, The multi-channel constant power-constant current driving circuit 100,
A driving circuit power generation circuit unit 110 connected to the voltage input terminal Vin of the LED driving circuit to generate power for the LED driving circuit;
A plurality of fixed terminals connected to each drive channel of the LED driving circuit and one switching terminal connected to the constant current driving circuit 130 according to the channel are provided, and the switching terminal is selected from any one of the plurality of fixed terminals. And a driving channel selection switch connected to each other, and sensing each driving channel voltage of the LED driving circuit to control the operation of the switching terminal according to each driving channel voltage detection result to control any one of the driving channels of the LED driving circuit. A driving channel voltage sensing and channel selection driving circuit unit 120 that connects to a constant current driving circuit unit 130 according to a channel; And
Multi-channel constant-power-driven LED driving circuit, characterized in that comprises a; constant current driving circuit unit 130 according to a channel for supplying a constant current for each channel to each driving channel of the LED driving circuit. According to claim 4, The multi-channel constant power-constant current driving circuit 100,
A plurality of driving channel switching temperature values TCsw for changing the driving channel of the LED driving circuit are set, and the temperature of the LED driving circuit is sensed to detect a channel changing signal for changing each driving channel according to the driving channel switching temperature value. Further comprising; a drive circuit temperature detection and channel change signal generation circuit section 140 to generate and transmit to the drive channel voltage detection and channel selection drive circuit section 120,
The driving channel voltage sensing and channel selection driving circuit unit 120,
A constant current driving circuit according to a channel controls any one of the driving channels of the LED driving circuit by controlling the operation of the switching terminal by a channel changing signal generated and transmitted by the driving circuit temperature sensing and channel changing signal generating circuit 140 LED driving circuit capable of driving a multi-channel constant power-constant current, characterized in that it is configured to be connected to (130). According to claim 4, The multi-channel constant power-constant current driving circuit 100,
A shutdown temperature value TS for shutdown of the constant current driving circuit unit 130 according to the channel is set, and when the heating temperature of the LED driving circuit is detected and a predetermined shutdown temperature value is detected, the constant current driving circuit unit 130 according to the channel ) Shutdown to maintain the temperature stability against the heat of the constant current driving circuit 130 according to the channel temperature protection circuit 150, multi-channel constant power-constant current driving LED drive assembly characterized in that further comprises in.

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