JP7006866B2 - LED drive circuit - Google Patents

LED drive circuit Download PDF

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JP7006866B2
JP7006866B2 JP2017153479A JP2017153479A JP7006866B2 JP 7006866 B2 JP7006866 B2 JP 7006866B2 JP 2017153479 A JP2017153479 A JP 2017153479A JP 2017153479 A JP2017153479 A JP 2017153479A JP 7006866 B2 JP7006866 B2 JP 7006866B2
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宗 藤原
堅次 武渕
智春 矢田
義規 加藤
王義 山崎
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New Japan Radio Co Ltd
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Description

本発明はＬＥＤ駆動回路に関する。 The present invention relates to an LED drive circuit.

図２に従来のＬＥＤ駆動回路を示す。１は電圧入力端子、２，３はｎ個（ｎは１以上の整数）のＬＥＤが直列接続された第１および第２のＬＥＤ群、４はＰＷＭ端子である。５は第１の制御回路であり、電圧入力端子１に入力する電圧ＶＩＮの高低を検出する電圧検知回路５１と、その電圧検知回路５１の検出結果に応じた制御信号を出力するスイッチ制御回路５２を含む。６は駆動回路であり、第１のＬＥＤ群２を駆動する第１の駆動部６１と、第２のＬＥＤ群３又は第１および第２のＬＥＤ群２，３の直列回路を駆動する第２の駆動部６２を含み、それらは所定の電流値を設定するとともに、ＰＷＭ端子に入力するＰＷＭ信号によって、電流のオン／オフを行う。７～１０はスイッチ制御回路５２でオン／オフが個別的に制御されるスイッチ回路である。 FIG. 2 shows a conventional LED drive circuit. 1 is a voltage input terminal, 2 and 3 are first and second LED groups to which n LEDs (n is an integer of 1 or more) are connected in series, and 4 is a PWM terminal. Reference numeral 5 denotes a first control circuit, which is a voltage detection circuit 51 that detects the height of the voltage VIN input to the voltage input terminal 1, and a switch control circuit 52 that outputs a control signal according to the detection result of the voltage detection circuit 51. including. Reference numeral 6 is a drive circuit, in which the first drive unit 61 for driving the first LED group 2 and the second LED group 3 or the second series circuit for the first and second LED groups 2 and 3 are driven. Including the drive unit 62 of the above, they set a predetermined current value and turn on / off the current by the PWM signal input to the PWM terminal. 7 to 10 are switch circuits whose on / off is individually controlled by the switch control circuit 52.

図２に示すＬＥＤ駆動回路の動作は、特許文献１に開示されているように、スイッチ回路７～１０のオン／オフを制御することにより、電圧入力端子１の入力電圧ＶＩＮが低い電圧のときは第１のＬＥＤ群２と第２のＬＥＤ群３を並列接続にして駆動し、電圧入力端子１の入力電圧ＶＩＮが高い電圧のときは第１のＬＥＤ群２と第２のＬＥＤ群３を直列接続にして駆動する。 As disclosed in Patent Document 1, the operation of the LED drive circuit shown in FIG. 2 is when the input voltage VIN of the voltage input terminal 1 is a low voltage by controlling the on / off of the switch circuits 7 to 10. Drives the first LED group 2 and the second LED group 3 in parallel, and when the input voltage VIN of the voltage input terminal 1 is high, the first LED group 2 and the second LED group 3 are connected. Drive in series connection.

このような構成にすることで、入力電圧ＶＩＮが低い電圧の場合には大きな順方向電圧ＶｆのＬＥＤも使用可能となり、また入力電圧ＶＩＮが高い電圧の場合には回路のダイナミックレンジを有効活用することができるとともに駆動回路６の電流値を制御することで第１のＬＥＤ群２と第２のＬＥＤ群３を並列接続した時と同じ輝度に設定することができる。 With such a configuration, when the input voltage VIN is low, an LED with a large forward voltage Vf can be used, and when the input voltage VIN is high, the dynamic range of the circuit is effectively utilized. By controlling the current value of the drive circuit 6, the same brightness as when the first LED group 2 and the second LED group 3 are connected in parallel can be set.

特開２０１５－１６７２１３号公報Japanese Unexamined Patent Publication No. 2015-167213

しかし、このようなＬＥＤ駆動回路ではスイッチ回路の一部で動作不良が起きた場合に問題が生じてしまう。例えば、スイッチ回路７動作不良となった場合、第１のＬＥＤ群２と第２のＬＥＤ群３を直列接続するときは第１のＬＥＤ群２と第２のＬＥＤ群３は問題なく点灯するが、並列接続する場合には第１のＬＥＤ群２が点灯しないことになる。また、スイッチ回路１０が動作不良となった場合、第１のＬＥＤ群２と第２のＬＥＤ群３を直列接続するときは第１のＬＥＤ群２と第２のＬＥＤ群３は問題なく点灯するが、並列接続する場合には第２のＬＥＤ群３が点灯しないことになる。 However, in such an LED drive circuit, a problem occurs when a malfunction occurs in a part of the switch circuit. For example, when the switch circuit 7 malfunctions, when the first LED group 2 and the second LED group 3 are connected in series, the first LED group 2 and the second LED group 3 light up without any problem. When connected in parallel, the first LED group 2 will not light up. Further, when the switch circuit 10 malfunctions, the first LED group 2 and the second LED group 3 light up without any problem when the first LED group 2 and the second LED group 3 are connected in series. However, when connected in parallel, the second LED group 3 does not light up.

このＬＥＤ駆動回路を航海灯ＬＥＤ照明灯の駆動回路として使用した場合、並列接続した第１のＬＥＤ群２と第２のＬＥＤ群３のいずれかが点灯しない状態では光量が不足し、航海灯の光量規定を逸脱するといった不具合が発生する。ところが、目視では光量不足は判別しづらいため、不具合状態を見逃してしまう可能性がある。 When this LED drive circuit is used as a drive circuit for a navigation light LED lighting, the amount of light is insufficient when either the first LED group 2 or the second LED group 3 connected in parallel is not lit, and the navigation light Problems such as deviation from the light intensity regulation occur. However, since it is difficult to visually determine the insufficient amount of light, there is a possibility that the defective state may be overlooked.

本発明は上記問題点を解消し、ＬＥＤ群の輝度レベルを所望のレベルに設定するとともに光量が不足した場合には目視で不具合状態を確認できるＬＥＤ駆動回路を提供することを目的とする。 It is an object of the present invention to solve the above-mentioned problems and to provide an LED drive circuit that can set the luminance level of the LED group to a desired level and visually confirm the defective state when the amount of light is insufficient.

上記目的を達成するために、
請求項１にかかる発明は、ｎ個（ｎは１以上の整数）のＬＥＤの直列回路からなる第１および第２のＬＥＤ群と、複数のスイッチ回路と、前記第１のＬＥＤ群に流れる電流を制御する第１の駆動部および前記第２のＬＥＤ群に流れる電流を制御する第２の駆動部を有する駆動回路と、電圧入力端子の電圧を検出して前記複数のスイッチ回路を個別にオン／オフ制御して前記第１のＬＥＤ群と前記第２のＬＥＤ群を並列接続あるいは直列接続するとともに前記駆動回路の前記第１および第２の駆動部を制御する第１の制御回路とを備えるＬＥＤ駆動回路であって、前記第１のＬＥＤ群を流れる電流を検知する第１の電流検知回路と前記第２のＬＥＤ群あるいは直列接続された前記第１のＬＥＤ群と前記第２のＬＥＤ群を流れる電流を検知する第２の電流検知回路と、前記電圧入力端子の電圧を検出して第１の定電流と第２の定電流を生成する定電流発生回路と、前記第１の電流検知回路で検知した電流と前記第１の定電流を比較する第１の電流比較回路と、前記第２の電流検知回路で検知した電流と前記第２の定電流を比較する第２の電流比較回路とを含む第２の制御回路とを備え、前記第１の制御回路は前記第１の電流比較回路および前記第２の電流比較回路の比較結果が正常であれば前記複数のスイッチ回路のオン／オフの状態を維持し、前記第１の電流比較回路あるいは前記第２の電流比較回路の比較結果が異常であれば前記複数のスイッチ回路をオフして全てのＬＥＤを消灯することを特徴とする。 To achieve the above objectives
The invention according to claim 1 is a first and second LED group composed of a series circuit of n LEDs (n is an integer of 1 or more), a plurality of switch circuits, and a current flowing through the first LED group. A drive circuit having a first drive unit for controlling the voltage and a second drive unit for controlling the current flowing through the second LED group, and the plurality of switch circuits individually for detecting the voltage of the voltage input terminal. A first control circuit that controls on / off to connect the first LED group and the second LED group in parallel or in series and to control the first and second drive units of the drive circuit. An LED drive circuit including a first current detection circuit for detecting a current flowing through the first LED group and the second LED group or the first LED group and the second LED connected in series. A second current detection circuit that detects the current flowing through the group, a constant current generation circuit that detects the voltage of the voltage input terminal and generates a first constant current and a second constant current, and the first current. A first current comparison circuit that compares the current detected by the detection circuit with the first constant current, and a second current comparison that compares the current detected by the second current detection circuit with the second constant current. A second control circuit including a circuit is provided, and the first control circuit turns on the plurality of switch circuits if the comparison result of the first current comparison circuit and the second current comparison circuit is normal. The feature is that the / off state is maintained, and if the comparison result of the first current comparison circuit or the second current comparison circuit is abnormal, the plurality of switch circuits are turned off and all the LEDs are turned off. do.

本発明によれば、各ＬＥＤ群に流れる電流が正常な電流値であることを検知し、正常であれば所望の状態を保持し、各ＬＥＤ群に電流が流れない等の異常がある場合にはスイッチ回路がオフに制御され、各ＬＥＤ群を全消灯することにより目視で不具合状態であることを確認することができる。 According to the present invention, when it is detected that the current flowing through each LED group is a normal current value, the desired state is maintained if it is normal, and there is an abnormality such as no current flowing through each LED group. The switch circuit is controlled to be off, and by turning off all the LEDs, it is possible to visually confirm that the state is defective.

本発明の実施例のＬＥＤ駆動回路の回路図である。It is a circuit diagram of the LED drive circuit of the Example of this invention. 従来のＬＥＤ駆動回路の回路である。It is a circuit of a conventional LED drive circuit.

以下、本発明について図を参照しながら説明する。なお、以下に説明する部材・配置等は本発明を限定するものではなく、本発明の趣旨の範囲内で種々改変することができるものである。図面において、同一番号は同等あるいは同一部分を示している。 Hereinafter, the present invention will be described with reference to the drawings. The members, arrangements, and the like described below are not limited to the present invention, and can be variously modified within the scope of the purpose of the present invention. In the drawings, the same numbers indicate the same or the same parts.

図１に本発明のＬＥＤ駆動回路を示す。１は電圧入力端子、２はｎ個の（ｎは１以上の整数）のＬＥＤが直列接続された第１のＬＥＤ群、３もｎ個のＬＥＤが直列接続された第２のＬＥＤ群、４はＰＷＭ端子である。５は第１の制御回路であり、電圧入力端子１に入力する電圧ＶＩＮの高低を検出する電圧検知回路５１と、その電圧検知回路５１の検出結果と後述する第２の制御回路１３から出力される制御信号に応じた制御信号を出力するスイッチ制御回路５２を含む。６は駆動回路であり、第１のＬＥＤ群２を駆動する第１の駆動部６１と、第２のＬＥＤ群３又は第１および第２のＬＥＤ群２，３の直列回路を駆動する第２の駆動部６２を含み、それらは所定の電流値を設定するとともに、ＰＷＭ端子４に入力するＰＷＭ信号によって、電流のオン／オフを行う。７～１０はスイッチ制御回路５２でオン／オフが個別的に制御されるスイッチ回路である。１１は第１の電流検知回路であり、第１のＬＥＤ群２に流れる電流を検知する。１２は第２の電流検知回路であり、第２のＬＥＤ群３あるいは第１および第２のＬＥＤ群２，３に流れる電流を検知する。１３は第２の制御回路であり、電圧検知回路５１の検出結果に応じて定電流を生成する定電流発生回路１３１と、定電流発生回路１３１で生成された第１の定電流Ｉｒｅｆ１と第１の電流検知回路１１の検知した電流を比較する第１の電流比較回路１３２と、定電流発生回路１３１で生成された第２の定電流Ｉｒｅｆ２と第２の電流検知回路１２の検知した電流を比較する第２の電流比較回路１３３を含む。 FIG. 1 shows the LED drive circuit of the present invention. 1 is a voltage input terminal, 2 is a first LED group in which n LEDs (n is an integer of 1 or more) are connected in series, and 3 is a second LED group in which n LEDs are connected in series. Is a PWM terminal. Reference numeral 5 is a first control circuit, which is output from a voltage detection circuit 51 that detects the height of the voltage VIN input to the voltage input terminal 1, a detection result of the voltage detection circuit 51, and a second control circuit 13 described later. A switch control circuit 52 that outputs a control signal corresponding to the control signal is included. Reference numeral 6 is a drive circuit, in which the first drive unit 61 for driving the first LED group 2 and the second LED group 3 or the second series circuit for the first and second LED groups 2 and 3 are driven. Including the drive unit 62 of the above, they set a predetermined current value and turn on / off the current by the PWM signal input to the PWM terminal 4. 7 to 10 are switch circuits whose on / off is individually controlled by the switch control circuit 52. Reference numeral 11 is a first current detection circuit, which detects the current flowing through the first LED group 2. Reference numeral 12 is a second current detection circuit, which detects the current flowing through the second LED group 3 or the first and second LED groups 2 and 3. Reference numeral 13 is a second control circuit, which is a constant current generation circuit 131 that generates a constant current according to the detection result of the voltage detection circuit 51, and a first constant current Iref 1 and a first constant current generated by the constant current generation circuit 131. The first current comparison circuit 132 that compares the currents detected by the current detection circuit 11 and the second constant current Iref2 generated by the constant current generation circuit 131 and the currents detected by the second current detection circuit 12 are compared. The second current comparison circuit 133 is included.

さて、電圧入力端子１には、高い電圧あるいは低い電圧ＶＩＮが入力する。まず、入力電圧ＶＩＮが、制御回路５の電圧検知回路５１において低い所望の電圧であると検知されたときは、スイッチ制御回路５２によって、スイッチ回路７，８，１０がオンに制御され、スイッチ回路９がオフに制御される。これにより、第１および第２のＬＥＤ群２，３が電圧入力端子１に対して並列接続される。そして、駆動回路６の駆動部６１，６２が互いに同じ電流値に設定され且つ同じＰＷＭ信号で制御されることで、第１および第２のＬＥＤ群２，３の各ＬＥＤがそのＰＷＭ制御に応じた同じ輝度で発光する。 Now, a high voltage or a low voltage VIN is input to the voltage input terminal 1. First, when the input voltage VIN is detected by the voltage detection circuit 51 of the control circuit 5 to be a low desired voltage, the switch control circuit 52 controls the switch circuits 7, 8 and 10 to be turned on, and the switch circuit. 9 is controlled off. As a result, the first and second LED groups 2 and 3 are connected in parallel to the voltage input terminal 1. Then, the drive units 61 and 62 of the drive circuit 6 are set to the same current value and controlled by the same PWM signal, so that the LEDs of the first and second LED groups 2 and 3 respond to the PWM control. It emits light with the same brightness.

また、第１の制御回路５の電圧検知回路５１の検出結果は第２の制御回路１３の定電流発生回路１３１へ入力され、定電流発生回路１３１は所望の定電流を生成し、第１の電流比較回路１３２へ第１の定電流Ｉｒｅｆ１を、第２の電流比較回路１３３へ第２の定電流Ｉｒｅｆ２を出力する。第１の電流検知回路１１では、第１のＬＥＤ群２に流れる電流を検知し、その検知した電流と第１の定電流Ｉｒｅｆ１を第２の制御回路１３の第１の電流比較回路１３２にて比較し、第１のＬＥＤ群２に流れる電流が所望の電流であることを検知する。同様に、第２の電流検知回路１２では、第２のＬＥＤ群３に流れる電流を検知し、その検知した電流と第２の定電流Ｉｒｅｆ２を第２の制御回路１３の第２の電流比較回路１３３にて比較し、第２のＬＥＤ群３に流れる電流が所望の電流であることを検知する。 Further, the detection result of the voltage detection circuit 51 of the first control circuit 5 is input to the constant current generation circuit 131 of the second control circuit 13, the constant current generation circuit 131 generates a desired constant current, and the first The first constant current Iref1 is output to the current comparison circuit 132, and the second constant current Iref2 is output to the second current comparison circuit 133. The first current detection circuit 11 detects the current flowing through the first LED group 2, and transfers the detected current and the first constant current Iref1 to the first current comparison circuit 132 of the second control circuit 13. By comparison, it is detected that the current flowing through the first LED group 2 is a desired current. Similarly, in the second current detection circuit 12, the current flowing in the second LED group 3 is detected, and the detected current and the second constant current Iref2 are combined with the second current comparison circuit of the second control circuit 13. Compared with 133, it is detected that the current flowing through the second LED group 3 is a desired current.

第１および第２のＬＥＤ群２，３に流れる電流が所望の電流である場合は、スイッチ制御回路５２によって、スイッチ回路７，８，１０がオンに制御されスイッチ回路９がオフに制御された状態を維持する。スイッチ回路等の異常により、第１および第２のＬＥＤ群２，３に流れる電流が所望の電流でないことを第１の電流比較回路１１あるいは第２の電流比較回路１２が検知した場合は、スイッチ制御回路５２によってスイッチ回路７～１０がオフに制御される。これにより第１および第２のＬＥＤ群２，３のどちらも点灯しないため、目視で不具合状態であることを確認することができる。 When the current flowing through the first and second LED groups 2 and 3 is a desired current, the switch control circuit 52 controls the switch circuits 7, 8 and 10 to be on and the switch circuit 9 to be turned off. Maintain the state. When the first current comparison circuit 11 or the second current comparison circuit 12 detects that the current flowing through the first and second LED groups 2 and 3 is not a desired current due to an abnormality in the switch circuit or the like, the switch is switched. The switch circuits 7 to 10 are controlled off by the control circuit 52. As a result, neither the first LED group nor the second LED group 2 or 3 is lit, so that it can be visually confirmed that the LED group is in a defective state.

次に、入力電圧ＶＩＮが、第１の制御回路５の電圧検知回路５１において高い所望の電圧であると検知されたときは、スイッチ制御回路５２によって、スイッチ回路８，９がオンに制御され、スイッチ回路７，１０がオフに制御される。これにより、第１および第２のＬＥＤ群２，３が電圧入力端子１に対して直列接続される。このとき、駆動回路６の駆動部６２がＰＷＭ制御されることで、第１および第２のＬＥＤ群２，３がそのＰＷＭ制御に応じた輝度で発光する。このとき、駆動部６２の電流値を、スイッチ制御回路５２によって、並列接続されていた際に第２のＬＥＤ群３に流れた電流値と同じ電流値に制御することで、第１および第２のＬＥＤ群２，３が並列接続されていた際に入力したＰＷＭ信号と同じＰＷＭ信号が入力する際に、直列接続された第１および第２のＬＥＤ群２，３の各ＬＥＤの輝度レベルを並列接続時の輝度レベルと同程度にすることができる。 Next, when the input voltage VIN is detected to be a high desired voltage in the voltage detection circuit 51 of the first control circuit 5, the switch control circuit 52 controls the switch circuits 8 and 9 to be turned on. The switch circuits 7 and 10 are controlled to be off. As a result, the first and second LED groups 2 and 3 are connected in series to the voltage input terminal 1. At this time, the drive unit 62 of the drive circuit 6 is PWM controlled, so that the first and second LED groups 2 and 3 emit light with the brightness corresponding to the PWM control. At this time, the current value of the drive unit 62 is controlled by the switch control circuit 52 to the same current value as the current value flowing through the second LED group 3 when they are connected in parallel, so that the first and second LEDs can be used. When the same PWM signal as the PWM signal input when the LEDs 2 and 3 are connected in parallel is input, the brightness level of each LED of the first and second LED groups 2 and 3 connected in series is set. It can be set to the same level as the brightness level when connected in parallel.

また、第１の制御回路５の電圧検知回路５１の検出結果は第２の制御回路１３の定電流発生回路１３１へ入力され、定電流発生回路１３１は所望の定電流を生成し、第２の制御回路１３の第２の電流比較回路１３３へ第２の定電流Ｉｒｅｆ２を出力する。第２の電流検知回路１２では、第１および第２のＬＥＤ群２，３に流れる電流を検知し、その検知した電流と第２の定電流Ｉｒｅｆ２を第２の制御回路１３の第２の電流比較回路１３３にて比較し、第１および第２のＬＥＤ群２，３に流れる電流が所望の電流であることを検知する。 Further, the detection result of the voltage detection circuit 51 of the first control circuit 5 is input to the constant current generation circuit 131 of the second control circuit 13, the constant current generation circuit 131 generates a desired constant current, and the second The second constant current Iref2 is output to the second current comparison circuit 133 of the control circuit 13. The second current detection circuit 12 detects the current flowing through the first and second LED groups 2 and 3, and uses the detected current and the second constant current Iref2 as the second current of the second control circuit 13. The comparison circuit 133 compares and detects that the current flowing through the first and second LED groups 2 and 3 is a desired current.

第１および第２のＬＥＤ群２，３に流れる電流が所望の電流である場合は、スイッチ制御回路５２によって、スイッチ回路８，９がオンに制御されスイッチ回路７，１０がオフに制御された状態を維持する。スイッチ回路等の異常により、第１および第２のＬＥＤ群２，３に流れる電流が所望の電流でないことを第２の電流比較回路１２が検知した場合は、スイッチ制御回路５２によってスイッチ回路７～１０がオフに制御される。これにより第１および第２のＬＥＤ群２，３のどちらも点灯しないため、目視で不具合状態であることを確認することができる。 When the current flowing through the first and second LED groups 2 and 3 is a desired current, the switch control circuit 52 controls the switch circuits 8 and 9 to be on and the switch circuits 7 and 10 to be turned off. Maintain the state. When the second current comparison circuit 12 detects that the current flowing through the first and second LED groups 2 and 3 is not a desired current due to an abnormality in the switch circuit or the like, the switch control circuit 52 detects the switch circuits 7 to 7. 10 is controlled off. As a result, neither the first LED group nor the second LED group 2 or 3 is lit, so that it can be visually confirmed that the LED group is in a defective state.

以上のように、本発明によれば、入力電圧の高低に応じて第１および第２のＬＥＤ群２，３を並列接続あるいは直列接続することで回路のダイナミックレンジを有効に活用してＬＥＤ群の輝度レベルを所望のレベルに設定することができるとともに、スイッチ回路等の異常により第１および第２のＬＥＤ群２，３に流れる電流が所望の電流とならず光量が不足した場合に不具合状態を目視で容易に確認することができる。 As described above, according to the present invention, the LED group can effectively utilize the dynamic range of the circuit by connecting the first and second LED groups 2 and 3 in parallel or in series according to the level of the input voltage. The brightness level can be set to a desired level, and a malfunction state occurs when the current flowing through the first and second LED groups 2 and 3 does not become the desired current due to an abnormality in the switch circuit or the like and the amount of light is insufficient. Can be easily confirmed visually.

１：電圧入力端子、２，３：ＬＥＤ群、４：ＰＷＭ端子、５：第１の制御回路、５１：電圧検知回路、５２：スイッチ制御回路、６：駆動回路、６１：第１の駆動部、６２：第２の駆動部、７～１０：スイッチ回路、１１：第１の電流検知回路、１２：第２の電流検知回路、１３：第２の制御回路、１３１：定電流発生回路、１３２：第１の電流比較回路、１３３：第２の電流比較回路 1: Voltage input terminal, 2, 3: LED group, 4: PWM terminal, 5: First control circuit, 51: Voltage detection circuit, 52: Switch control circuit, 6: Drive circuit, 61: First drive unit , 62: 2nd drive unit, 7-10: switch circuit, 11: 1st current detection circuit, 12: 2nd current detection circuit, 13: 2nd control circuit, 131: constant current generation circuit, 132 : First current comparison circuit 133: Second current comparison circuit

Claims (1)

ｎ個（ｎは１以上の整数）のＬＥＤの直列回路からなる第１および第２のＬＥＤ群と、複数のスイッチ回路と、前記第１のＬＥＤ群に流れる電流を制御する第１の駆動部および前記第２のＬＥＤ群に流れる電流を制御する第２の駆動部を有する駆動回路と、電圧入力端子の電圧を検出して前記複数のスイッチ回路を個別にオン／オフ制御して前記第１のＬＥＤ群と前記第２のＬＥＤ群を並列接続あるいは直列接続するとともに前記駆動回路の前記第１および第２の駆動部を制御する第１の制御回路とを備えるＬＥＤ駆動回路であって、
前記第１のＬＥＤ群を流れる電流を検知する第１の電流検知回路と前記第２のＬＥＤ群あるいは直列接続された前記第１のＬＥＤ群と前記第２のＬＥＤ群を流れる電流を検知する第２の電流検知回路と、前記電圧入力端子の電圧を検出して第１の定電流と第２の定電流を生成する定電流発生回路と、前記第１の電流検知回路で検知した電流と前記第１の定電流を比較する第１の電流比較回路と、前記第２の電流検知回路で検知した電流と前記第２の定電流を比較する第２の電流比較回路とを含む第２の制御回路とを備え、
前記第１の制御回路は前記第１の電流比較回路および前記第２の電流比較回路の比較結果が正常であれば前記複数のスイッチ回路のオン／オフの状態を維持し、前記第１の電流比較回路あるいは前記第２の電流比較回路の比較結果が異常であれば前記複数のスイッチ回路をオフして全てのＬＥＤを消灯する、
ことを特徴とするＬＥＤ駆動回路。 A first and second LED group consisting of a series circuit of n LEDs (n is an integer of 1 or more), a plurality of switch circuits, and a first drive unit that controls a current flowing through the first LED group. A drive circuit having a second drive unit that controls the current flowing through the second LED group, and the first switch circuit that detects the voltage of the voltage input terminal and individually turns on / off the plurality of switch circuits. An LED drive circuit including a first control circuit for connecting the LED group and the second LED group in parallel or in series and controlling the first and second drive units of the drive circuit.
A first current detection circuit that detects the current flowing through the first LED group and the second LED group or a second LED group that detects the current flowing through the first LED group and the second LED group connected in series. The current detection circuit of 2, the constant current generation circuit that detects the voltage of the voltage input terminal and generates the first constant current and the second constant current, the current detected by the first current detection circuit, and the above. A second control including a first current comparison circuit for comparing the first constant current and a second current comparison circuit for comparing the current detected by the second current detection circuit with the second constant current. Equipped with a circuit,
If the comparison result of the first current comparison circuit and the second current comparison circuit is normal, the first control circuit maintains the on / off state of the plurality of switch circuits, and the first current If the comparison result of the comparison circuit or the second current comparison circuit is abnormal, the plurality of switch circuits are turned off and all the LEDs are turned off .
An LED drive circuit characterized by this.
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CN104936330A (en) 2014-03-18 2015-09-23 赵依军 LED driving power supply and LED illuminating device comprising the same
JP2015167213A (en) 2014-03-04 2015-09-24 新日本無線株式会社 Led driving circuit
JP2016201514A (en) 2015-04-14 2016-12-01 新日本無線株式会社 Led drive circuit and led drive method
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JP2004527138A (en) 2001-05-25 2004-09-02 コーニンクレッカ　フィリップス　エレクトロニクス　エヌ　ヴィ LED power supply
JP2009252344A (en) 2008-04-01 2009-10-29 Sharp Corp White led driving circuit for lighting, and lighting fixture and electronic device provided with the same
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