JP6513546B2 - LED power supply - Google Patents

Description

  The present invention relates to an LED power supply device, and more particularly to improvement of an LED load abnormality detection function and control circuit maintenance function at the time of abnormality detection.

  In recent years, replacement of conventional LED with light sources is rapidly progressing due to the improvement of luminous efficiency and life of LED elements. In the future, if the performance of the LED element is improved, it is expected that the LED light source will be adopted in the field of general lighting equipment, and the demand for a lighting power supply device such as an LED power supply device will increase. In general, the LED power supply device is for applying a DC voltage to an LED element which does not operate with commercial AC voltage to operate the LED element properly. And, for example, the LED power supply device in recent years changes the DC voltage value supplied to the LED element and adjusts the current value to the LED element to adjust the light control function, the input side (primary side) By isolating the output side (secondary side) from the output side (secondary side) by using a transformer, various devices have been made to provide a safety function or the like that enhances safety.

In Patent Document 1, two types of voltage supply circuits, a first voltage supply circuit and a second voltage supply circuit, are provided in the start-up circuit of the switching power supply device, and voltage is supplied by the first voltage supply circuit (stable When a sudden change in load occurs, the output voltage to the load is stopped and the second voltage supply circuit is switched to maintain the operation of only the control circuit that controls the switching power supply circuit. It is disclosed.
In addition, Patent Document 2 discloses a power control IC having an automatic reset type overload protection function (a function that automatically recovers after an abnormality is released instead of maintaining a stopped state). Even if it is not built in, there is disclosed a technology that maintains a constant voltage by connecting a resistor R0 between the power supply terminal VCC and the smoothing capacitor C1 and can maintain the stop state at the time of overload.

Japanese Patent Application Publication No. 2004-320858 Patent No. 5141438

  However, by providing two types of voltage supply circuits in the start-up circuit provided in the switching power supply as in Patent Document 1 described above, it is possible to realize stop of the output voltage in sudden changes of load etc. and maintenance of operation of the control circuit. However, it has not been possible to realize the function of maintaining the operation of the control circuit while detecting an abnormal state such as a short circuit or a no-load state to stop the output. In addition, when using the LED power supply, in practice, when load fluctuation occurs, appropriate control is performed according to the load fluctuation without stopping the output to the LED element, and a short circuit state, no load state, etc. It is desirable to stop the output to the LED element and maintain the operation of the control circuit only when it is difficult to maintain the operation of the circuit.

  Then, when voltage maintenance is performed depending on the resistance value as in Patent Document 2, it is necessary to change the resistance value according to the type of input voltage, and power consumption increases. In addition, as in Patent Document 1 and Patent Document 2, using a Zener diode (an element capable of outputting a constant voltage) as a voltage supply circuit for maintaining the operation of the control circuit (power supply control IC) in the output stop state is simple. However, constant current characteristics can not be maintained if a large current flows due to fluctuations in the input power supply, etc., so it is difficult to maintain stable control circuit operation. There is room for

  The present invention has been made in view of the above-mentioned problems of the prior art, and the object thereof is to perform appropriate control with respect to load fluctuation of the LED power supply device and detect a short circuit on the load side and no load condition detection. Sometimes, the output is stopped and the stable operation maintaining function of the control circuit at the time of the output stop is provided.

In order to solve the above-mentioned subject, the LED power supply concerning the present invention is:
An input-side rectifying and smoothing circuit that rectifies an AC voltage from a commercial power supply, a control circuit that appropriately controls a voltage supplied to the LED element, a power supply circuit that supplies a voltage to the control circuit, and the input-side rectifying and smoothing circuit Main circuit switching means for adjusting the voltage value by switching the rectified voltage; and an output side rectification smoothing circuit for rectifying the voltage adjusted by the main circuit switching means and supplying a DC voltage to the LED element LED power supply provided,
The output side rectifying and smoothing circuit includes a current detection unit that detects a current value to the LED element and also detects a short circuit state, and a no-load detection unit that detects a no-load state in which the LED element is not connected.
The power supply circuit includes a voltage supply switch that properly adjusts a voltage to the control circuit by performing a switching operation.
The control circuit has a two-step control mode of a normal operation mode for performing control at the time of normal operation of the LED element and an abnormality detection mode for performing control at the time of abnormality detection;
In the normal operation mode, an appropriate voltage is supplied to the LED element by switching the main circuit switching means,
The abnormality detection mode stops the switching operation of the main circuit switching means when the control circuit receives an abnormality detection signal, and changes the off-duty ratio by the switching operation of the voltage supply switch, thereby the control circuit Supply a voltage to the control circuit that can only operate.

Further, a transformer is provided between the main circuit switching means and the output side rectifying and smoothing circuit, and an auxiliary winding is provided on the primary side of the transformer,
An auxiliary power supply circuit for supplying a voltage from the auxiliary winding by the switching operation of the main circuit switching means to the control circuit;
Preferably, the auxiliary power supply circuit supplies a voltage to the control circuit after the stable operation of the LED element.

The power supply circuit further includes an auxiliary switch which is turned off when the voltage supply switch is on and is turned on when the voltage supply switch is off;
In the abnormality detection mode, the switching operation of the main circuit switching element is stopped, and the voltage supply from the auxiliary power supply circuit to the control circuit is stopped.
By adjusting the off-duty ratio of the voltage supply switch by the switching operation of the auxiliary switch, it is preferable to supply to the control circuit a voltage that can be maintained only by the control circuit.

According to the present invention, by providing the output-side rectifying and smoothing circuit with the insulation type current detection means and the insulation type no-load detection means as well, appropriate control according to the load fluctuation can be performed, and an output short circuit or no load. When the state is detected, it is possible to stop the output to the LED load.
Furthermore, the power supply circuit for start-up is provided with a voltage supply switch and an auxiliary switch, and when an abnormality occurs (when a short circuit is detected or no load is detected), the auxiliary switch adjusts the off duty ratio of the voltage supply switch. By supplying an appropriate voltage from the voltage supply switch to the control circuit, it is possible to stably maintain the operation of the control circuit in the output stop state at the time of output short circuit and no load, without depending on the input power supply It becomes.

The schematic block diagram of 1st Embodiment of the LED power supply device which concerns on this invention is shown. FIG. 1 shows a schematic view of a control circuit in a first embodiment of an LED power supply device according to the present invention. The voltage change in each point with respect to the time progress in 1st Embodiment of the LED power supply device which concerns on this invention is shown. The schematic block diagram of 2nd Embodiment of the LED power supply device which concerns on this invention is shown.

Hereinafter, although the LED power supply device of this invention is demonstrated using drawing, it is not limited to the following examples at all, unless the meaning of this invention is exceeded.
First Embodiment

  FIG. 1 is a schematic view of an LED power supply device according to a first embodiment of the present invention. The LED power supply device 10 shown in the figure includes a commercial power supply 12 for supplying commercial AC voltage, an input-side rectifying and smoothing circuit 14 for rectifying AC voltage, and a startup power supply circuit 16 for supplying voltage to the control circuit 18. The control circuit 18 performs switching control of the main circuit switching element 22, the auxiliary power supply circuit 20 that supplies a voltage to the control circuit 18 after startup, and the high-speed switching operation of the voltage rectified by the input-side rectifying and smoothing circuit 14 Thus, the main circuit switching element 22 (for adjusting the voltage value by adjusting the duty ratio) for generating a high frequency rectangular wave voltage and the peak value (voltage value) of the high frequency rectangular wave voltage are properly set. And a flyback transformer 24 for electrically insulating the primary side from the secondary side, and converting the rectangular wave voltage adjusted to an appropriate value into a DC voltage An output-side rectifying and smoothing circuit 26 for supplying a DC voltage to the ED load (LED elements 28), and a.

  Characteristic of the present invention is that the output side rectifying and smoothing circuit 26 is provided with a current detection operational amplifier 30 for detecting an output current and a short circuit, and a no load detection operational amplifier 32 for detecting a no-load state of the LED element 28. It is The start-up power supply circuit 16 is provided with an auxiliary switch Q2 and a voltage supply switch Q1 which is turned off when the auxiliary switch Q2 is on and is turned off when the auxiliary switch Q2 is off.

First, the input side rectifying and smoothing circuit 14 will be described.
The input side rectifying and smoothing circuit 14 includes a diode bridge DB and a smoothing capacitor C1. When an AC commercial voltage (such as AC 100 or AC 200 V) is applied by the commercial power supply 12, the commercial voltage reaches the diode bridge DB. The diode bridge DB is configured of a diode element or the like, but may be another semiconductor element as long as it can perform the same function. The voltage (also called pulsating voltage) that has been full-wave rectified (both positive and negative waves of alternating current are rectified and the flow direction is made the same) by diode bridge DB is a rough DC voltage by smoothing capacitor C1. (It is necessary to further integrate the integration circuit to obtain a complete DC voltage).

  The smoothed voltage reaches the main circuit switching element 22 and also reaches the starting power supply circuit 16. The start-up power supply circuit 16 includes resistors R1 to R4, a diode D1 for backflow prevention, a voltage supply switch Q1 formed of an FET, a Zener diode Z1 for generating a constant voltage, and an FET, and an auxiliary switch It is comprised from voltage supply switch Q1 which turns off when Q2 is on, and turns on when auxiliary switch Q2 is off.

  A constant voltage (Zener voltage) is generated at both ends of the Zener diode Z1 by the resistor R2 and the Zener diode Z1, and the voltage at both ends of the Zener diode Z1 is the gate voltage necessary for conducting the voltage supply switch Q1. The voltage thus drawn charges the capacitor C2. That is, when the voltage supply switch Q1 is turned on, charging of the charging capacitor C2 is started. When the voltage of the charging capacitor C2, that is, the voltage of P2, exceeds a certain value (about 5 V at which the CPU included in the control circuit 18 can operate), the control circuit 18 starts operation.

  When the control circuit 18 starts its operation, the control operation of the control circuit 18 starts the switching operation of the main circuit switching element 22 of FIG. By this switching operation, the voltage smoothed by the input side rectifying and smoothing circuit 14 becomes a high frequency rectangular wave voltage, and proceeds to the primary side Tla of the flyback transformer 24. The flyback transformer 24 adjusts the voltage value supplied from the commercial power supply 12 to a voltage value (or current value) appropriate for supplying the LED element 28, and the primary winding Tla which is the primary side of the flyback transformer 24. By electrically insulating the secondary winding Tlb on the secondary side, to enhance safety.

  Here, the operation of the flyback type power supply device will be briefly described. When the main circuit switching element 22 is on, the conduction loop from the positive pole side of the input side rectifying and smoothing circuit 14 to the negative pole side of the primary winding Tla of the flyback transformer 24, the main circuit switching element 22 and the input side rectifying and smoothing circuit 14 is The energy of the magnetic field is accumulated in the primary winding Tla of the flyback transformer 24 by applying the voltage which is formed and rectified by the input side rectification smoothing circuit 14. On the other hand, when it is off, the conduction loop is broken, and the current accompanying the discharge of the energy of the magnetic field from the secondary winding Tlb of the flyback transformer 24 flows through the diode D3 and the smoothing capacitor C3 in this order, Return to the 24 secondary windings Tlb. Such an operation generates a desired output current (and an output voltage corresponding to the output current) on the secondary winding Tlb side of the transformer 24.

  Then, the high frequency rectangular wave voltage advanced to the secondary winding Tlb of the flyback transformer 24 reaches the output side rectifying and smoothing circuit 26. The output-side rectifying / smoothing circuit 26 detects resistances R5 to R7, a diode D3, a smoothing capacitor C3, an output current, and a current detection operational amplifier 30 capable of detecting an output short circuit and a no-load state. A no load detection operational amplifier 32 is provided. The high frequency rectangular wave voltage is rectified to a DC voltage by the diode D 3 and the smoothing capacitor C 3, and the DC voltage is supplied to the LED element 28. The current detection operational amplifier 30 detects the current of the resistor R5 and feeds it back to the control circuit 18 to realize current detection. Therefore, since the control circuit 18 properly controls the switching operation while issuing a control command to the main circuit switching element 22 so that the current value to the LED element 28 is always appropriate, the stability of the LED element 28 is stable. Operation is possible.

Here, the operation of the control circuit 18 will be described in detail.
FIG. 2 shows a schematic view of the control circuit 18 in the first embodiment of the LED power supply device 10 according to the present invention. The control circuit 18 mainly includes an MCU (Micro Controller Unit) including a CPU, an FET driver for controlling the main circuit switching element 22, and a three-terminal regulator. The MCU also includes an I / O for sending a control signal to the auxiliary switch Q2, and an A / D for receiving a short circuit detection signal based on the current value of R5 and a no load detection signal based on the voltage value of R6. The MCU, which is a main part of the control circuit 18, operates at a voltage (5 V) obtained by converting a voltage of 12 V to 20 V, which is a supply voltage from P2 of FIG. 1, by the three-terminal regulator. That is, in order to maintain the operation of the control circuit 18, it is sufficient if a voltage of about 5 V can be secured. The voltage does not have to be exactly 5 V, for example, about 4 V to 10 V, and any voltage value may be used as long as the operating voltage of the MCU (or the CPU of the MCU) can be secured.

  Then, as described above, the control circuit 18 properly adjusts the switching operation of the main circuit switching element 22 by the feedback signal of the current detection operational amplifier 30 when the LED element 28 is in stable operation. Since the current supplied to the LED element 28 is determined while constantly monitoring the current value as the feedback signal, even if the LED element 28 fluctuates, the LED power supply device 10 in this embodiment It is possible to control appropriately according to the change. In addition, the LED power supply device 10 according to the present embodiment can stop the output when some trouble that is difficult to maintain the operation occurs (for example, a load short circuit or a no-load state). Specifically, the current detection operational amplifier 30 monitoring the current as a feedback signal detects the output current and at the same time the short circuit current can also be detected. Therefore, if a short circuit occurs, the control circuit 18 instantaneously The operation of the main circuit switching element 22 is stopped, and at the same time, the voltage output to the load side (the LED element 28 side) is stopped. Also, no-load detection such as no-load state is constantly monitored by the no-load detection operational amplifier 32. Therefore, if a no-load state is detected, the control circuit 18 receives the signal (no-load detection signal), stops the operation of the main circuit switching element 22 as in the short circuit, and outputs the voltage to the load side. Stop.

  In this manner, by constantly monitoring the current value as a feedback signal and also constantly monitoring the short circuit detection and no load detection by the control circuit 18, an appropriate current value can be supplied in the case of a simple load fluctuation. In the case where it is difficult to maintain the operation (at the time of short circuit detection and no load detection), the output to the load side can be immediately stopped.

  Generally, when the output to the load side is stopped, the voltage supply to the control circuit 18 is also stopped. However, in order to further enhance the safety, the control circuit is also stopped in the state where the output to the LED element 28 is stopped. It is necessary to maintain 18 operations. Therefore, in the present embodiment, it is devised that only the voltage supply to the control circuit 18 can be performed even when the output to the load side is stopped.

  Specifically, in addition to the voltage supply switch Q1 for adjusting the voltage supply to the start-up power supply circuit 16 in the LED power supply device 10 according to the present embodiment, the control circuit 18 detects a short circuit and no load. There is an auxiliary switch Q2 that allows proper voltage supply at the voltage supply switch Q1 only. Here, the operation of the auxiliary switch Q2 will be described together with the operation of the LED power supply 10 (flow until the voltage supplied from the commercial power supply 12 reaches the LED element 28) with reference to FIG.

  FIG. 3 shows the voltage change at each point with respect to the passage of time in the first embodiment of the LED power supply device according to the present invention. In FIG. 3, at time t1 when the power is turned on, the auxiliary switch Q2 is in the OFF state, and the charging voltage of the capacitor C2 is 0V. Then, a Zener voltage by the Zener diode Z1 is applied to the voltage between the gate and the source of the voltage supply switch Q1, the voltage supply switch Q1 is turned ON, and charging is performed through the resistor R1 and the diode D1 of the startup power supply circuit 16. The capacitor C2 is charged. When the voltage of the charging capacitor C2, that is, the voltage of P2, gradually rises and the current value flowing through R1 and the current value consumed by the control circuit 18 become equal, the voltage increase of P2 stops (FIG. 3) T2).

  Next, when the control circuit 18 starts operation and operates the switching elements of the switching circuit 22 of FIG. 1, the voltage of P2 further rises by the auxiliary power supply circuit 20 and reaches a constant value (time t3 in FIG. 3). P2). The auxiliary power supply circuit 20 includes an auxiliary winding Tlc added to the flyback transformer 24, a diode D2 that rectifies an induced voltage of the auxiliary winding Tlc, and a capacitor C2 for charging. The cathode of the diode D2 is connected to the positive electrode side of the capacitor C2. Since the positive electrode side of the capacitor C2 is also connected to P2 described above, the capacitor C2 can receive power supply from both of the starting power supply circuit 16 and the auxiliary power supply circuit 20. At this time, a stop signal is sent from the control circuit 18 to the start-up power supply circuit 16, and the auxiliary switch Q2 is turned on (Q2 at t3 in FIG. 3). Further, since the voltage between the gate and the source of the voltage supply switch Q1 is a negative voltage, the voltage supply switch Q1 is turned off (Q1 at time t3 in FIG. 3), and the LED element 28 is turned on. At this time, the control circuit 18 continues the lighting control of the LED element 28.

  When the no-load detection operational amplifier 32 detects a no-load state or the current detection operational amplifier 30 detects a short circuit in the stable operation state (LED lighting state) of the LED element 28, those detection signals are sent to the control circuit 18 The output to the LED element 28 is stopped by the control of the control circuit 18 (t4 in FIG. 4).

  At this time, the operation of the main circuit switching element 22 is stopped, and the charging of the charging capacitor C2 is stopped, so the operation of the auxiliary power supply circuit 20 which supplies the power to the control circuit 18 is also stopped.

Here, in order to maintain the operation of the control circuit 18, the switching operation of the auxiliary switch Q2 of the start-up power supply circuit 16 creates a voltage (about 5 V) at which only the control circuit 18 operates.
As described above, the voltage supply switch Q1 is configured to be turned off when the auxiliary switch Q2 is turned on, and turned on when the auxiliary switch Q2 is turned off. Therefore, specifically, at least the CPU of the control circuit 18 operates by switching the switching operation of the auxiliary switch Q2 configured of the FET by the CPU having the control circuit 18 and adjusting the off-duty ratio of the voltage supply switch Q1. By generating a voltage (about 5 V) at which P2 can maintain the voltage of P2, the operation of the control circuit 18 can be maintained even when the output to the LED element 28 is stopped.

  Further, as described above, the auxiliary switch Q2 is configured by a switching element such as an FET. For example, even if the supply voltage from the commercial power supply 12 fluctuates due to some influence, the switching operation of the auxiliary switch Q2 causes Since an appropriate voltage (about 5 V) can be generated by adjusting the off-duty ratio, a stable power supply for control circuit 18 is not provided, or a plurality of power supply means is not provided, and stable control circuit 18 can be produced. Operation can be maintained. In addition, whether the voltage from the commercial power supply 12 is 100 V or 200 V, for example, the auxiliary switch Q2 performs proper switching operation (off of the voltage supply switch Q1) in accordance with the power supply voltage. By performing control to adjust the duty ratio, stable operation maintenance of the control circuit 18 is possible.

  Then, when the power supply is turned on again, if the short circuit state or no load state is eliminated, the normal operation is performed, and if not eliminated, the similar operation (the output stop and the operation control of only the control circuit 18) is repeated. It will be.

  As described above, in the present embodiment, by providing the output-side rectifying / smoothing circuit 16 with the isolated output current detection operational amplifier 30 and the isolated no-load detection operational amplifier 32 as well, appropriate control according to the load fluctuation is performed. When it is difficult to maintain the operation by detecting an output short circuit or no load condition, the output to the LED element 28 can be stopped. Further, the power supply circuit for start-up 16 is provided with a voltage supply switch Q1 composed of FETs as switching elements, and an auxiliary switch Q2, and the switching operation of the auxiliary switch Q2 properly adjusts the off-duty ratio of the voltage supply switch Q1. By doing this, it is possible to stably maintain the operation of the control circuit 18 in the output stop state at the output short circuit and no load time without depending on the input power supply (such as the commercial power supply 12). For example, regardless of whether the input power supply is 100 V or 200 V, the switching operation by the auxiliary switch Q2 enables appropriate voltage supply (about 5 V) from the voltage supply switch Q1. The operation of the control circuit 18 can be maintained at the occurrence of an abnormality without changing the circuit configuration of FIG.

Further, in the LED power supply device 10 according to the present embodiment, by supplying an appropriate voltage that only the control circuit 18 (at least the CPU) can operate, the commercial voltage can be switched without the switching operation of the auxiliary switch Q2 when the output is stopped in the abnormality occurrence. Power consumption can be significantly reduced as compared with a system in which the control circuit 18 is directly supplied.
Second Embodiment

  Next, an LED power supply device according to a second embodiment of the present invention will be described using the drawings. The configuration common to the LED power supply device 10 (first embodiment) shown in FIG. 1 is indicated by adding 100 to the reference numerals.

  FIG. 4 is a schematic view of an LED power supply device according to a second embodiment of the present invention. The basic configuration of the LED power supply device 110 in FIG. 4 is the same as that of the LED power supply device 10 shown in FIG. 1 described above, but in the present embodiment, the force between the input side rectifying and smoothing circuit 114 and the main circuit switching element 122 A rate improvement circuit 140 is provided. Therefore, in the LED power supply device 110 according to the present embodiment, the distortion of the waveform due to the influence of harmonics from the input voltage is improved, and voltage supply to the LED element 128 becomes possible. Therefore, the LED power supply according to the first embodiment Power can be supplied more efficiently than the device 10.

  Since the voltage supply to the PFC control circuit included in the power factor correction circuit 140 is performed by the voltage supply switch Q1 (the auxiliary power supply circuit 120 after the stable operation of the LED element 128), the secondary side of the transformer 124 If a short circuit state or no load state is detected in the winding Tlb side and the output is stopped by the control circuit 118, the operation of the power factor correction circuit 140 is also stopped, and as in the first embodiment, the auxiliary switch By the switching operation of Q2 (control to adjust the off-duty ratio of the voltage supply switch Q1), it is possible to stably maintain only the control circuit 118 with the proper voltage from the voltage supply switch Q1.

  As described above, according to the LED power supply device of the present invention, proper control according to the load fluctuation can be achieved by providing the output-side rectifying and smoothing circuit with the isolated current detection operational amplifier and the isolated no load detection operational amplifier. With this operation, it is possible to detect an output short circuit or no load condition, and to stop the output to the LED element in the scene leading to the occurrence of a serious accident. In addition, the power supply circuit for start-up is provided with a voltage supply switching element and an auxiliary switching element, and when an abnormality occurs (at the time of short circuit detection or no load state detection) the off duty ratio of the voltage supply switching element is determined by the auxiliary switching element. By adjusting and supplying an appropriate voltage from the voltage supply switching element to the control circuit, the operation maintenance of the control circuit in the output stop state at the time of output short circuit and no load is stable without depending on the input power supply. It is possible to do

10 110 LED power supply 12 112 commercial power supply 14 114 input side rectification smoothing circuit 16 116 starting power supply circuit 18 118 control circuit 20 120 auxiliary power supply circuit 22 122 main circuit switching element 24 124 flyback transformer 26 126 output side rectification smoothing circuit 28 128 LED element 30 130 current detection operational amplifier 32 132 no load detection operational amplifier
140 Power factor correction circuit R1 to R7 Resistors D1 to D3 Diodes C1 and C3 Smoothing capacitor C2 Charging capacitor Q1 Voltage supply switch Q2 Auxiliary switch Tla Primary winding Tlb Secondary winding Tlc Auxiliary winding Z1 Zener diode

Claims (3)

An input-side rectifying and smoothing circuit that rectifies an AC voltage from a commercial power supply, a control circuit that appropriately controls a voltage supplied to the LED element, a power supply circuit that supplies a voltage to the control circuit, and the input-side rectifying and smoothing circuit Main circuit switching means for adjusting the voltage value by switching the rectified voltage; and an output side rectification smoothing circuit for rectifying the voltage adjusted by the main circuit switching means and supplying a DC voltage to the LED element LED power supply provided,
The output side rectifying and smoothing circuit includes a current detection unit that detects a current value to the LED element and also detects a short circuit state, and a no-load detection unit that detects a no-load state in which the LED element is not connected.
The power supply circuit includes a voltage supply switch that properly adjusts a voltage to the control circuit by performing a switching operation.
The control circuit has a two-step control mode of a normal operation mode for performing control at the time of normal operation of the LED element and an abnormality detection mode for performing control at the time of abnormality detection;
In the normal operation mode, an appropriate voltage is supplied to the LED element by switching the main circuit switching means,
The abnormality detection mode stops the switching operation of the main circuit switching means when the control circuit receives an abnormality detection signal, and changes the off-duty ratio by the switching operation of the voltage supply switch, thereby the control circuit An LED power supply device, which supplies a voltage to the control circuit that can only maintain operation. The LED power supply device according to claim 1, wherein
A transformer is provided between the main circuit switching means and the output side rectifying and smoothing circuit, and an auxiliary winding is provided on the primary side of the transformer,
An auxiliary power supply circuit for supplying a voltage from the auxiliary winding by the switching operation of the main circuit switching means to the control circuit;
The auxiliary power supply circuit supplies a voltage to the control circuit after stable operation of the LED element. The LED power supply device according to any one of claims 1 and 2, wherein
The power supply circuit includes an auxiliary switch which is turned off when the voltage supply switch is on and is turned on when the voltage supply switch is off;
In the abnormality detection mode, the switching operation of the main circuit switching element is stopped, and the voltage supply from the auxiliary power supply circuit to the control circuit is stopped.
An LED power supply device characterized in that a voltage which can be maintained only by the control circuit is supplied to the control circuit by adjusting the off-duty ratio of the voltage supply switch by the switching operation of the auxiliary switch.

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