JP2015185405A - LED lighting device - Google Patents
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本発明は、 ＬＥＤを点灯させるＬＥＤ点灯装置に関する。 The present invention relates to an LED lighting device that lights an LED.
従来、 発光ダイオード(ＬＥＤ：Light Emitting Diode) を点灯するＬＥＤ点灯装置として、 直流電流により点灯するＬＥＤを点灯制御するＬＥＤ点灯装置が知られている (特許文献1)。
このＬＥＤ点灯装置は、 直流電流により点灯するＬＥＤに対して直列にインダクタとスイッチング素子が接統され、 ＬＥＤとインダクタとの直列回路と並列に接続され、スイッチング素子のオフ時にインダクタの蓄積エネルギーを半導体発光素子に放出する方向に接続された回生ダイオードを備えた降圧チョッバ回路と、スイッチング索子をオン/オフさせる制御回路とを備える。
制御回略は、スイッチング素子のオン時にインダクタに流れる漸増電流の瞬時値が所定値に達するとスイッチング索子をオフする手段と、スイッチング素子のオフ時にインダクタに流れる漸減電流が略ゼロになるとスイッチング素子をオンする手段とを備える。
2. Description of the Related Art Conventionally, as an LED lighting device that lights a light emitting diode (LED), an LED lighting device that controls lighting of an LED that is lit by a direct current is known (Patent Document 1).
In this LED lighting device, an inductor and a switching element are connected in series to an LED that is lit by a direct current, and is connected in parallel to a series circuit of the LED and the inductor, and the stored energy of the inductor is semiconductor when the switching element is off. A step-down chopper circuit having a regenerative diode connected in a direction to emit light to the light emitting element and a control circuit for turning on / off the switching cord are provided.
The control circuit consists of means for turning off the switching element when the instantaneous value of the increasing current flowing through the inductor when the switching element is turned on reaches a predetermined value, and the switching element when the decreasing current flowing through the inductor when the switching element is turned off becomes substantially zero. And means for turning on.
従来のＬＥＤ点灯裝置においては、スイッチング素子のオフ時にインダクタに流れる漸減電流が略ゼロになると、スイッチング素子をオンすることにより平均電流制御を行うことができるが、臨界モード制御のためインダクタに流れる電流のピーク値が大きく、スイッチングオフ時の損失が大きくなる。
また、入力電圧変動によりスイッチング素子のオフからオンになるタイミングが変化し、発振周波数が変動するので、スイッチング損失も変動してしまう。
しかしながら、スイッチング素子に流れる電流のピーク値を画定したＰＷＭ (pulse width Modulation) 制御では、入力電圧変動があるときには平均電流制御を行うことができないという問題がある。
In the conventional LED lighting device, when the gradually decreasing current flowing through the inductor when the switching element is turned off becomes approximately zero, the average current control can be performed by turning on the switching element, but the current flowing through the inductor for critical mode control. The peak value of is large, and the loss when switching off is large.
In addition, the timing at which the switching element is turned on is changed due to the input voltage variation, and the oscillation frequency varies, so that the switching loss also varies.
However, in PWM (pulse width modulation) control in which the peak value of the current flowing through the switching element is defined, there is a problem that the average current control cannot be performed when the input voltage varies.
また、ＬＥＤを点灯させるためのＬＥＤ願動回路は、一般に定電流で制御を行う。 従来のＰＷＭ制御を行う降圧型のＬＥＤ駆動回路では、ＬＥＤがフローティングされており、ＬＥＤを流れる電流を検出するための電流検出部ではローサイド (ＧＮＤライン) 検出が不可能である。 このため、平均電流検出を行う時はＬＥＤに流れる電流を直接に検出するフローティングされた電流検出回路が必要である。
しかしながら、フローティングされた電流検出回路を使用すると、電流検出回路と制御回路との間の耐圧を高くする必要があるので、フォトカプラ等により信号を絶緑する回路や高耐圧部品を採用しなければならず、高コストとなる問題がある。
本発明の課題は、入力電圧変動があっても平均電流制御を行うことができ、しかも簡単な構成で安価なＬＥＤ点灯装置を提供することにある。
Further, the LED driving circuit for turning on the LED is generally controlled with a constant current. In a conventional step-down LED drive circuit that performs PWM control, the LED is floating, and a low-side (GND line) detection is impossible in a current detection unit for detecting a current flowing through the LED. For this reason, when the average current detection is performed, a floating current detection circuit for directly detecting the current flowing through the LED is required.
However, if a floating current detection circuit is used, it is necessary to increase the withstand voltage between the current detection circuit and the control circuit. However, there is a problem of high cost.
An object of the present invention is to provide an LED lighting device that can perform average current control even when there is an input voltage fluctuation and that is inexpensive and has a simple configuration.
前記課題を解決するために、本発明のＬＥＤ点灯装置は、直流電源と、前記直流電源の両端にＬＥＤとインダクタとスイッチング素子と電流検出抵抗とが直列に接続された直列回路と、前記ＬＥＤと前記インダクタとの直列回路に並列に接続された回生ダイオードと、前記スイッチング索子がオンの時の電流を検出する手段と、前記電流検出手段で得られた信号と所定の基準値とを比較して得た誤差信号を電流変換して制御電流とする電流増幅器と、コンデンサと、前記スイッチング索子がオンの時に前記制御電流をコンデンサに充放電させるスイッチとを有し、
前記スイッチング素子をオンオフ制御し且つ前記コンデンサの電圧に基づき前記スイッチング索子のオン期間の電流平均値が一定になるようにＰＷＭ制御して前記ＬＥＤに流れる電流を一定に制御するＰＷＭ制御回路とを備えることを特徴とする。
In order to solve the above problems, an LED lighting device according to the present invention includes a DC power supply, a series circuit in which an LED, an inductor, a switching element, and a current detection resistor are connected in series at both ends of the DC power supply; A regenerative diode connected in parallel to a series circuit with the inductor, a means for detecting a current when the switching element is on, and a signal obtained by the current detection means are compared with a predetermined reference value. A current amplifier that converts the error signal obtained in this way into a control current, a capacitor, and a switch that charges and discharges the control current to the capacitor when the switching cord is on,
A PWM control circuit that performs on-off control of the switching element and performs PWM control based on the voltage of the capacitor so that a current average value during an on period of the switching element is constant, thereby controlling a current flowing through the LED to be constant. It is characterized by providing.
本発明に係わるＬＥＤ点灯装置によれば、スイッチング素子がオンの時の電流と、所定の基準値とを比較して誤差信号を電流変換し、前記スイッチング索子がオンの時に前記電流変換された誤差信号でコンデンサを充放電し、ＰＷＭ制御回路がコンデンサの電圧に基づきスイッチング素子のオン期間の電流平均値が一定になるようにＰＷＭ制御してＬＥＤに流れる電流を一定に制御するので、入力電圧変動があっても平均電流制御を行うことができ、しかも簡単な構成で安価なＬＥＤ点灯装置を提供できる。 According to the LED lighting device of the present invention, the current when the switching element is on is compared with a predetermined reference value to convert the error signal into current, and the current is converted when the switching cord is on. The capacitor is charged and discharged with the error signal, and the PWM control circuit performs PWM control so that the average current value during the ON period of the switching element is constant based on the voltage of the capacitor, thereby controlling the current flowing to the LED constant. Even if there is a fluctuation, the average current control can be performed, and an inexpensive LED lighting device can be provided with a simple configuration.
以下、本発明の実施の形態のＬＥＤ点灯装置を、図面を参照しながら詳細に説明する。 Hereinafter, an LED lighting device according to an embodiment of the present invention will be described in detail with reference to the drawings.
図１は、本発明の実施例１のＬＥＤ点灯装置の回路図である。図２は、本発明の実施例１のＬＥＤ点灯装置の動作を説明するためのタイミングチャートである。ＬＥＤ点灯装置は、負極が接地され電圧Ｖｉｎを発生する直流電源ＶＩＮ、直流電源ＶＩＮの正極にアノードが接続され、電流ＩＬＥＤが流れることにより発光する複数のＬＥＤ（ＬＥＤｓ）、一端がＬＥＤのカソードに接続されたインダクタＬ１、ドレインがインダクタＬ１の他端に接続されたスイッチング素子Ｑ１、一端がスイッチング素子Ｑ１のソースに接続され、他端が接地された電流検出抵抗Ｒ１を備える。
ＬＥＤとインダクタＬ１との直列回路に並列に回生ダイオードＤ１が接続され、回生ダイオードＤ１は、スイッチング素子Ｑ１のオフ時にインダクタＬ１の蓄積エネルギーをＬＥＤに放出する方向に接続される。
FIG. 1 is a circuit diagram of an LED lighting device according to Embodiment 1 of the present invention. FIG. 2 is a timing chart for explaining the operation of the LED lighting device according to the first embodiment of the present invention. The LED lighting device has a DC power source VIN that has a negative electrode grounded and generates a voltage Vin, an anode connected to the positive electrode of the DC power source VIN, and a plurality of LEDs (LEDs) that emit light when a current ILED flows, and one end is the cathode of the LED A connected inductor L1, a switching element Q1 whose drain is connected to the other end of the inductor L1, a current detection resistor R1 whose one end is connected to the source of the switching element Q1, and whose other end is grounded.
A regenerative diode D1 is connected in parallel to the series circuit of the LED and the inductor L1, and the regenerative diode D1 is connected in a direction to release the stored energy of the inductor L1 to the LED when the switching element Q1 is turned off.
スイッチング素子Ｑ１のゲートには、スイッチング素子Ｑ１のオン／オフを制御するＰＷＭ制御回路１０のｄｒｉｖ端子が接続される。ＰＷＭ制御回路１０のｓｅｎｓ端子には、スイッチング素子Ｑ１のソースと電流検出抵抗Ｒ１とが接続され、ＰＷＭ制御回路１０のｃｏｍｐ端子には、位相補正用のコンデンサＣ２の一端が接続され、コンデンサＣ２の他端は接地されている。
ＰＷＭ制御回路１０は、電流検出用の電流増幅器ＯＴＡ１、スイッチＳＷ１、三角波発振器ＯＳＣ１，コンパレータＣＰ１、ドライバＤＲＶを備える。
ＰＷＭ制御回路１０は、スイッチング素子Ｑ１をオンオフ制御し、且つ、コンデンサＣ２の電圧に基づきスイッチング素子のオン期間の電流平均値が一定になるようにＰＷＭ制御してＬＥＤに流れる電流を一定に制御する。
The drive terminal of the PWM control circuit 10 that controls on / off of the switching element Q1 is connected to the gate of the switching element Q1. The source of the switching element Q1 and the current detection resistor R1 are connected to the sens terminal of the PWM control circuit 10, and one end of the capacitor C2 for phase correction is connected to the comp terminal of the PWM control circuit 10. The other end is grounded.
The PWM control circuit 10 includes a current amplifier OTA1 for current detection, a switch SW1, a triangular wave oscillator OSC1, a comparator CP1, and a driver DRV.
The PWM control circuit 10 controls on / off of the switching element Q1, and controls the current flowing in the LED to be constant by performing PWM control so that the current average value during the on period of the switching element becomes constant based on the voltage of the capacitor C2. .
本発明の定電流制御信号発生回路は、電流増幅器ＯＴＡ１、基準電圧Ｖｔｈ１，スイッチＳＷ１、コンデンサＣ２から構成されている。
電流増幅器ＯＴＡ１の非反転入力端子には、ｓｅｎｓ端子を介してスイッチング素子Ｑ１のソースと電流検出抵抗Ｒ１とが接続される。電流増幅器ＯＴＡ１の反転入力端子には、基準電圧Ｖｔｈ１の正極が接続され、基準電圧Ｖｔｈ１の負極と抵抗Ｒ１の他端は接地されている。
ｃｏｍｐ端子には、スイッチＳＷ１を介して電流増幅器ＯＴＡ１の出力が接続され、且つコンデンサＣ２の一端が接続され、コンデンサＣ２の他端は接地されている。ｃｏｍｐ端子には、コンデンサＣ２を充放電するための制御電流Ｉｃｏｍｐが流れる。即ち、スイッチング素子Ｑ１のオン期間と同期させてスイッチＳＷ１を導通させて、電流増幅器ＯＴＡ１からの誤差信号電流を制御電流Ｉｃｏｍｐとして、コンデンサＣ２を充電または放電する。
より詳しくは、図２（ａ）Ｉｃｏｍｐ波形に示すように、電圧ＶｄｒｉｖのＨレベル期間の前半では、制御電流ＩｃｏｍｐによるコンデンサＣ２の充電が行われ、後半ではコンデンサＣ２の放電が行われる。コンデンサＣ２の充放電により、コンデンサＣ２には、制御電圧Ｖｃｏｍｐが発生する。
三角波発振器ＯＳＣ１は、三角波信号を発生してコンパレータＣＰ１の反転入力端子に出力する。コンパレータＣＰ１は、三角波発振器ＯＳＣ１からの三角波とｃｏｍｐ端子の制御電圧Ｖｃｏｍｐとを比較し、比較出力信号をドライバＤＲＶに出力する。ドライバＤＲＶは、電圧Ｖｄｒｉｖをｄｒｉｖ端子を介してＰＷＭ信号としてスイッチング素子Ｑ１のゲートに出力する。
即ち、ＬＥＤ点灯装置の定電流制御は、ｃｏｍｐ端子の制御電圧Ｖｃｏｍｐと三角波発振器ＯＳＣ１からの三角波とを比較することで、ｄｒｉｖ端子から出力されるＰＷＭ信号のデューティーを制御することにより行われる。
また、制御電圧Ｖｃｏｍｐは、制御電流ＩｃｏｍｐとコンデンサＣ２の容量により応答速度が決定されるので、コンデンサＣ２の容量を調整することで、電流増幅器ＯＴＡ１の利得を調整しなくても、定電流制御の位相補償を変更することが可能である。
The constant current control signal generation circuit according to the present invention includes a current amplifier OTA1, a reference voltage Vth1, a switch SW1, and a capacitor C2.
The source of the switching element Q1 and the current detection resistor R1 are connected to the non-inverting input terminal of the current amplifier OTA1 via a sens terminal. The inverting input terminal of the current amplifier OTA1 is connected to the positive electrode of the reference voltage Vth1, and the negative electrode of the reference voltage Vth1 and the other end of the resistor R1 are grounded.
The comp terminal is connected to the output of the current amplifier OTA1 via the switch SW1, and one end of the capacitor C2 is connected to the other end of the capacitor C2. A control current Icomp for charging and discharging the capacitor C2 flows through the comp terminal. That is, the switch SW1 is turned on in synchronization with the ON period of the switching element Q1, and the capacitor C2 is charged or discharged using the error signal current from the current amplifier OTA1 as the control current Icomp.
More specifically, as shown in FIG. 2 (a) Icomp waveform, the capacitor C2 is charged by the control current Icomp in the first half of the H level period of the voltage Vdrive, and the capacitor C2 is discharged in the second half. Due to charging / discharging of the capacitor C2, a control voltage Vcomp is generated in the capacitor C2.
The triangular wave oscillator OSC1 generates a triangular wave signal and outputs it to the inverting input terminal of the comparator CP1. The comparator CP1 compares the triangular wave from the triangular wave oscillator OSC1 with the control voltage Vcomp at the comp terminal, and outputs a comparison output signal to the driver DRV. The driver DRV outputs the voltage Vdrive to the gate of the switching element Q1 as a PWM signal via the drive terminal.
That is, the constant current control of the LED lighting device is performed by controlling the duty of the PWM signal output from the drive terminal by comparing the control voltage Vcomp of the comp terminal with the triangular wave from the triangular wave oscillator OSC1.
Further, since the response speed of the control voltage Vcomp is determined by the control current Icomp and the capacitance of the capacitor C2, the constant current control can be performed without adjusting the gain of the current amplifier OTA1 by adjusting the capacitance of the capacitor C2. It is possible to change the phase compensation.
また、インダクタＬ１に流れる電流が連続モードの時、インダクタＬ１にエネルギーを蓄えている期間中の電流を検出することにより、スイッチング素子Ｑ１がオフしている期間にインダクタＬ１のエネルギーが放出される期間中の電流も合わせて平均化することが可能となる。
図２は、ＬＥＤ点灯装置の動作を説明するためのタイミングチャートであって、図２（ａ）は直流電源ＶＩＮの電圧Ｖｉｎが低い入力時、図２（ｂ）は直流電源ＶＩＮの電圧Ｖｉｎが高い入力時を示す。直流電源ＶＩＮの電圧Ｖｉｎが低い入力の場合には、図２（ａ）に示すように、ＰＷＭ制御回路１０のｄｒｉｖ端子から電圧Ｖｄｒｉｖとして出力されるＰＷＭ信号のオン幅が長くなるように制御される。
In addition, when the current flowing through the inductor L1 is in the continuous mode, the period during which the energy of the inductor L1 is released while the switching element Q1 is off by detecting the current during the period in which the energy is stored in the inductor L1. It is possible to average the current inside.
FIG. 2 is a timing chart for explaining the operation of the LED lighting device. FIG. 2A shows a case where the voltage Vin of the DC power source VIN is low, and FIG. Indicates high input. When the voltage Vin of the DC power supply VIN is low, as shown in FIG. 2A, the PWM signal output as the voltage Vdrive from the drive terminal of the PWM control circuit 10 is controlled to be long. The
一方、電圧変動によって直流電源ＶＩＮの電圧Ｖｉｎが高くなると、図２（ｂ）に示すように、ＰＷＭ制御回路１０のｄｒｉｖ端子から電圧Ｖｄｒｉｖとして出力されるＰＷＭ信号のオン幅が短くなるように制御される。いずれの場合も、ＰＷＭ信号の周期は一定である。これにより、電圧変動により入力電圧が変化しても、ＬＥＤに流れる電流ＩＬＥＤが一定になるように制御される。 On the other hand, when the voltage Vin of the DC power supply VIN increases due to voltage fluctuation, control is performed so that the ON width of the PWM signal output as the voltage Vdrive from the drive terminal of the PWM control circuit 10 is shortened as shown in FIG. Is done. In either case, the period of the PWM signal is constant. Thereby, even if the input voltage changes due to voltage fluctuation, the current ILED flowing through the LED is controlled to be constant.
このように本発明の実施例１のＬＥＤ点灯装置によれば、従来のスイッチングオフ時に生じる損失と入力電圧変動に起因する発振周波数の変動によるスイッチング損失を回避しつつ、入力電圧変動があってもＰＷＭ制御による平均電流制御を行うことができる。
また、直流電源ＶＩＮとドライバとなるスイッチング素子Ｑ１との間に負荷であるＬＥＤを接続し、直流電源ＶＩＮから負荷を通ってドライバに流れこむ電流を制御するローサイド方式を採用し、ローサイド側でＬＥＤの電流を検出するので、回路の簡素化が可能であるとともに、安価な部品を使用でき、コンデンサの容量変更で位相補償が得られ、簡単な構成で安価なＬＥＤ点灯装置を提供できる。
As described above, according to the LED lighting device of Embodiment 1 of the present invention, even when there is an input voltage fluctuation while avoiding the switching loss due to the fluctuation of the oscillation frequency caused by the loss and the input voltage fluctuation caused by the conventional switching-off. Average current control by PWM control can be performed.
In addition, an LED, which is a load, is connected between the DC power source VIN and the switching element Q1 serving as a driver, and a low-side method is used in which the current flowing from the DC power source VIN through the load to the driver is controlled. Therefore, the circuit can be simplified, inexpensive components can be used, phase compensation can be obtained by changing the capacitance of the capacitor, and an inexpensive LED lighting device can be provided with a simple configuration.
図３は実施例２のＬＥＤ点灯装置の構成を示す図である。実施例２のＬＥＤ点灯装置１ａは、ディミング信号電圧ＤＩＭを追加するとともに、ＰＷＭ制御回路１０ａが実施例１のＬＥＤ点灯装置１と異なる。
即ち、ＰＷＭ制御回路１０ａは、実施例１のＰＷＭ制御回路１０にＡＮＤ回路ＡＮＤ１を追加し、ｄｉｍｍ端子を設けている。
実施例２は、外部調光信号のディミング信号電圧ＤＩＭに応じてＬＥＤ点灯装置１ａのＬＥＤの光出力を調光するものである。
FIG. 3 is a diagram illustrating a configuration of the LED lighting device according to the second embodiment. The LED lighting device 1a of the second embodiment adds a dimming signal voltage DIM, and the PWM control circuit 10a is different from the LED lighting device 1 of the first embodiment.
That is, the PWM control circuit 10a adds an AND circuit AND1 to the PWM control circuit 10 of the first embodiment, and is provided with a dimm terminal.
In the second embodiment, the light output of the LED of the LED lighting device 1a is dimmed according to the dimming signal voltage DIM of the external dimming signal.
ＰＷＭ制御回路１０ａは、実施例１のＰＷＭ制御回路１０に対して、外部調光信号のディミング信号電圧ＤＩＭを接続するｄｉｍｍ端子が設けられている。ここで、ＰＷＭ制御回路１０ａは、実施例１のＰＷＭ制御回路１０に対して、ｄｉｍｍ端子に一方の入力が接続されたＡＮＤ回路ＡＮＤ１と、ＡＮＤ回路ＡＮＤ１の入出力が、コンパレータＣＰ１の出力からドライバＤＲＶの入力とスイッチＳＷ１のオンオフ制御端子との間に接続されている点が異なる。
即ち、実施例２は、外部調光信号のディミング信号電圧ＤＩＭのパルス信号に応じて、ＡＮＤ回路１を介してコンパレータＣＰ１からのＰＷＭ信号をオン／オフすることでＬＥＤ点灯装置１ａのＬＥＤの光出力を調光するものである。
The PWM control circuit 10a is provided with a dimm terminal for connecting the dimming signal voltage DIM of the external dimming signal to the PWM control circuit 10 of the first embodiment. Here, the PWM control circuit 10a is different from the PWM control circuit 10 of the first embodiment in that the AND circuit AND1 has one input connected to the dimm terminal, and the input / output of the AND circuit AND1 is a driver from the output of the comparator CP1. The difference is that it is connected between the DRV input and the ON / OFF control terminal of the switch SW1.
That is, in the second embodiment, the LED light of the LED lighting device 1a is turned on / off by turning on / off the PWM signal from the comparator CP1 via the AND circuit 1 in accordance with the pulse signal of the dimming signal voltage DIM of the external dimming signal. The output is dimmed.
このように本発明の実施例２のＬＥＤ点灯装置１ａによれば、従来のスイッチングオフ時に生じる損失と入力電圧変動に起因する発振周波数の変動によるスイッチング損失を回避しつつ、入力電圧変動があってもＰＷＭ制御による平均電流制御を行い、かつ、外部調光信号のディミング信号に基づきＬＥＤの光出力を調光することができる。
また、実施例１のＰＷＭ制御回路にＡＮＤ回路ＡＮＤ１の追加のみで外部調光を可能とし、回路の簡素化が可能であるとともに、安価な部品を使用でき、簡単な構成で安価なＬＥＤ点灯装置を提供できる。
As described above, according to the LED lighting device 1a of the second embodiment of the present invention, the input voltage fluctuates while avoiding the switching loss due to the fluctuation of the oscillation frequency due to the loss at the time of switching off and the input voltage fluctuation. In addition, average current control by PWM control can be performed, and the light output of the LED can be dimmed based on the dimming signal of the external dimming signal.
In addition, external dimming is possible only by adding an AND circuit AND1 to the PWM control circuit of the first embodiment, the circuit can be simplified, inexpensive parts can be used, and an inexpensive LED lighting device with a simple configuration Can provide.
本発明は、ＬＥＤを利用した照明器具、照明システムなどに利用可能である。 The present invention can be used for lighting fixtures, lighting systems, and the like using LEDs.
１、１ａ ＬＥＤ点灯装置
１０、１０ａ ＰＷＭ制御回路
ＶＩＮ 直流電源
Ｑ１ スイッチング素子
Ｒ１ 電流検出抵抗
Ｄ１ 回生ダイオード
ＬＥＤｓ 発光ダイオード
Ｌ１ インダクタ
ＯＴＡ１ 電流増幅器
ＣＰ１ コンパレータ
ＯＳＣ１ 三角波発振器
ＡＮＤ１ ＡＮＤ回路
ＤＲＶ ドライバ
ＳＷ１ スイッチ
Ｃ１，Ｃ２ コンデンサ
1, 1a LED lighting device 10, 10a PWM control circuit VIN DC power supply Q1 switching element R1 current detection resistor D1 regenerative diode LEDs light emitting diode L1 inductor OTA1 current amplifier CP1 comparator OSC1 triangular wave oscillator AND1 AND circuit DRV driver SW1 switch C1, C2 capacitor
Claims (2)
前記スイッチング素子をオンオフ制御し且つ前記コンデンサの電圧に基づき前記スイッチング索子のオン期間の電流平均値が一定になるようにＰＷＭ制御して前記ＬＥＤに流れる電流を一定に制御するＰＷＭ制御回路とを備えることを特徴とするＬＥＤ点灯装置。 A DC power supply, a series circuit in which an LED, an inductor, a switching element, and a current detection resistor are connected in series at both ends of the DC power supply, and a regenerative diode connected in parallel to the series circuit of the LED and the inductor, A current amplifier for detecting a current when the switching cord is on; and a current amplifier for converting the error signal obtained by comparing the signal obtained by the current detection means and a predetermined reference value into a control current And a capacitor, and a switch for charging and discharging the control current to the capacitor when the switching cord is on,
A PWM control circuit that performs on-off control of the switching element and performs PWM control based on the voltage of the capacitor so that a current average value during an on period of the switching element is constant, thereby controlling a current flowing through the LED to be constant. An LED lighting device comprising:
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| JP2013132107A (en) * | 2011-12-20 | 2013-07-04 | Rohm Co Ltd | Dc/dc converter and control circuit and control method for current driver, and light-emitting device and electronic equipment using them |
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| JP2010170845A (en) * | 2009-01-22 | 2010-08-05 | Panasonic Electric Works Co Ltd | Power supply and luminaire using the same |
| JP2013132107A (en) * | 2011-12-20 | 2013-07-04 | Rohm Co Ltd | Dc/dc converter and control circuit and control method for current driver, and light-emitting device and electronic equipment using them |
| JP2013132186A (en) * | 2011-12-22 | 2013-07-04 | Rohm Co Ltd | Control circuit of switching power supply for driving light-emitting element, and light-emitting device and electronic apparatus using the same |
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