LED drive circuit and LED device with high power factor and low harmonics

Abstract

The present invention belongs to the technical field of LED driving, and discloses a high power factor and low harmonic LED driving circuit and an LED device. A voltage divider circuit divides a DC voltage to generate a reference voltage, and a clamp circuit outputs an analog signal equal to the reference voltage; a constant current circuit controls an output current according to the analog signal so that the output current is proportional to the analog signal, or controls the output current so that the output current is proportional to the reference voltage so that the output current of the constant current circuit is proportional to the DC voltage, thereby reducing the harmonic distortion of the high power factor and low harmonic LED driving circuit.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED driving, and in particular relates to an LED driving circuit and an LED device with high power factor and low harmonics. Background Art

[0002] Conventional LED drive circuits generally use constant current drive, and constant current drive using operational amplifiers and switching elements generally has problems of low power factor and excessive harmonic distortion, especially for high-power LED drive circuits, where the problems of low power factor and harmonic distortion are more obvious. Therefore, conventional LED drive circuits are improved by using segmented drive circuits to drive LEDs, thereby improving their power factor. However, this drive mode still does not solve the problem of excessive harmonic distortion. Therefore, a high power factor and low harmonic LED drive circuit is needed to solve the problem of excessive harmonic distortion in LED drive. Summary of the invention

[0003] In view of this, the embodiments of the present invention provide a high power factor and low harmonic LED driving circuit and LED device, aiming to solve the problem of excessive harmonic distortion existing in traditional technical solutions.

[0004] A first aspect of an embodiment of the present invention provides a high power factor and low harmonic LED driving circuit, wherein the high power factor and low harmonic LED driving circuit comprises a voltage divider circuit, an LED component, N clamping circuits, N+1 constant current circuits, and a current limiting component;

[0005] The voltage divider circuit is configured to divide the DC voltage to generate a reference voltage when a DC voltage is connected;

[0006] The LED assembly includes N+1 loads connected in series in sequence, the N+1 loads include a first load to an N+1th load, the positive electrode of the first load is connected to a DC voltage, and the negative electrode of the kth load is connected to the positive electrode of the k+1th load; wherein N is an integer greater than or equal to 1, and k is a positive integer less than or equal to N;

[0007] an i-th clamping circuit, connected to the voltage divider circuit, configured to output an analog signal equal to the reference voltage when the reference voltage is less than the clamping voltage of the i-th clamping circuit and when the reference voltage is greater than or equal to the clamping voltage of the i-1-th clamping circuit; wherein i is a positive integer less than or equal to N;

[0008] a jth constant current circuit, connected to the jth clamping circuit, the jth load, the j+1th load and the current limiting component, and configured to control the output current according to the analog signal so that the output current is proportional to the analog signal; wherein j is a positive integer less than or equal to N;

[0009] an N+1th constant current circuit, connected to the N+1th load, the voltage divider circuit and the current limiting component, and configured to control the output current so that the output current is proportional to the reference voltage when the reference voltage is greater than or equal to the clamping voltage of the Nth clamping circuit and the reference voltage is less than an upper limit voltage;

[0010] The current limiting component is configured to limit the output current of the constant current circuit.

[0011] In one embodiment of the first aspect, each of the N clamping circuits includes a clamping component, wherein the clamping component includes a first operational amplifier, a second operational amplifier, a first field effect transistor, and a first resistor;

[0012] The non-inverting input terminal of the first operational amplifier is the reference voltage input terminal of the clamp circuit, the non-inverting input terminal of the second operational amplifier is the clamp voltage input terminal of the clamp circuit, the inverting input terminal of the first operational amplifier, the inverting input terminal of the second operational amplifier, the source of the first field effect tube and the first end of the first resistor together constitute the output terminal of the clamp circuit, the output terminal of the first operational amplifier and the output terminal of the second operational amplifier are commonly connected to the gate of the first field effect tube, the drain of the first field effect tube is connected to the internal power supply, and the second end of the first resistor is connected to the power ground.

[0013] In one embodiment of the first aspect, each of the N constant current circuits includes a constant current component, and the constant current component includes a third operational amplifier and a second field effect transistor;

[0014] The non-inverting input terminal of the third operational amplifier is the analog signal input terminal of the constant current component, the output terminal of the third operational amplifier is connected to the gate of the second field effect tube, the negative phase input terminal of the third operational amplifier and the source of the second field effect tube together constitute the output current output terminal of the constant current component, and the drain of the second field effect tube is the input voltage input terminal of the constant current component;

[0015] The N+1th constant current circuit includes a fourth operational amplifier and a third field effect transistor;

[0016] The non-inverting input terminal of the fourth operational amplifier is the upper limit voltage input terminal of the N+1th constant current circuit, the output terminal of the fourth operational amplifier is connected to the gate of the third field effect transistor, the negative input terminal of the fourth operational amplifier and the source of the third field effect transistor together constitute the output current output terminal of the N+1th constant current circuit, and the drain of the third field effect transistor is the input voltage input terminal of the N+1th constant current circuit.

[0017] In one embodiment of the first aspect, the voltage divider circuit includes a second resistor and a third resistor, and the second end of the second resistor and the first end of the third resistor together constitute a reference voltage output end of the voltage divider circuit; the first end of the second resistor is a DC voltage first input end of the voltage divider circuit, and the second end of the third resistor is a DC voltage second input end of the voltage divider circuit.

[0018] In one embodiment of the first aspect, the high power factor and low harmonic LED driving circuit further includes:

[0019] A rectifier circuit is connected to the AC power and used to rectify the AC power to generate a DC voltage.

[0020] In one embodiment of the first aspect, the rectifier circuit includes a first diode, a second diode, a third diode and a fourth diode; the anode of the first diode and the anode of the fourth diode together constitute a second DC voltage output terminal of the rectifier circuit, the cathode of the first diode and the anode of the second diode together constitute a first AC input terminal of the rectifier circuit, the cathode of the second diode and the cathode of the third diode together constitute the first DC voltage output terminal of the rectifier circuit, and the anode of the third diode and the cathode of the fourth diode together constitute a second AC input terminal of the rectifier circuit.

[0021] A second aspect of the embodiments of the present invention provides an LED device, wherein the LED device comprises the high power factor and low harmonic LED driving circuit described in any embodiment of the first aspect.

[0022] The above-mentioned high power factor and low harmonic LED driving circuit is provided with N clamping circuits and N+1 constant current circuits; when the reference voltage is less than the clamping voltage of the i-th clamping circuit and when the reference voltage is greater than or equal to the clamping voltage of the i-1-th clamping circuit, the i-th clamping circuit outputs an analog signal equal to the reference voltage to the j-th constant current circuit, and the j-th constant current circuit controls the output current according to the analog signal so that the output current is proportional to the analog signal; when the reference voltage is greater than or equal to the clamping voltage of the N-th clamping circuit and the reference voltage is less than the upper limit voltage, the N+1-th constant current circuit controls the output current so that the output current is proportional to the reference voltage; therefore, in the N clamping circuits and the N+1 constant current circuits, the output current of the LED driving circuit is kept proportional to the DC voltage, thereby reducing the harmonic distortion of the LED driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A principle block diagram of a high power factor and low harmonic LED driving circuit provided by an embodiment of the present application;

[0025] Figure 2 A circuit schematic diagram of a clamping assembly provided in one embodiment of the present application;

[0026] Figure 3 A circuit schematic diagram of a constant current component provided in one embodiment of the present application;

[0027] Figure 4 A circuit schematic diagram of the N+1th constant current circuit provided in an embodiment of the present application;

[0028] Figure 5 A circuit schematic diagram of a voltage divider circuit provided in an embodiment of the present application;

[0029] Figure 6 A principle block diagram of a high power factor and low harmonic LED driving circuit provided by another embodiment of the present application;

[0030] Figure 7 A circuit schematic diagram of a rectifier circuit provided in one embodiment of the present application;

[0031] Figure 8 A circuit schematic diagram of a high power factor and low harmonic LED driving circuit provided by an embodiment of the present application;

[0032] Fig. 9 The output voltage and current waveforms of the LED driving circuit with high power factor and low harmonics in this application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] like Figure 1 As shown, an embodiment of the present invention provides a high power factor and low harmonic LED driving circuit. For the convenience of explanation, only the parts related to this embodiment are shown, which are described in detail as follows: a high power factor and low harmonic LED driving circuit. The high power factor and low harmonic LED driving circuit 1 includes a voltage divider circuit 101, an LED component 11, N clamping circuits, N+1 constant current circuits and a current limiting component 14.

[0035] The voltage divider circuit 101 is configured to divide the DC voltage to generate a reference voltage when a DC voltage is connected.

[0036] The LED component 11 includes N+1 loads connected in series in sequence, and the N+1 loads include a first load 111 to an N+1th load 11n+1. The positive pole of the first load 111 is connected to a DC voltage, and the negative pole of the kth load is connected to the positive pole of the k+1th load; wherein N is an integer greater than or equal to 1, which is equivalent to the LED component 11 including at least 2 loads; wherein k is a positive integer not greater than N.

[0037] The i-th clamp circuit 12i among the N clamp circuits is connected to the voltage divider circuit 101, and the i-th clamp circuit 12i inputs a reference voltage. The i-th clamp circuit 12i is also configured to output an analog signal equal to the reference voltage when the reference voltage is less than the clamp voltage of the i-th clamp circuit 12i and when the reference voltage is greater than or equal to the clamp voltage of the i-1-th clamp circuit; wherein the clamp voltage of the i-1-th clamp circuit is less than the clamp voltage of the i-th clamp circuit 12i; wherein i is a positive integer less than or equal to N, because N is an integer greater than or equal to 1, so the minimum value of i is 1; it should be noted that when N is 1, that is, when i is also 1, the i-1-th clamp circuit does not exist, and at this time the first clamp circuit is configured to output an analog signal equal to the reference voltage when the reference voltage is less than the clamp voltage of the first clamp circuit 121.

[0038] The N+1 constant current circuits include N constant current circuits and the N+1th constant current circuit. Among them, the jth constant current circuit 13j of the N constant current circuits is respectively connected to the jth clamping circuit, the jth load, the j+1th load and the current limiting component 14; the jth constant current circuit 13j is also configured to control the output current according to the analog signal so that the output current is proportional to the analog signal; wherein j is a positive integer less than or equal to N. The output current of the jth constant current circuit 13j is proportional to the analog signal, the analog signal is equal to the reference voltage, and the reference voltage is obtained by dividing the DC voltage, so when the output current of the jth constant current circuit 13j is proportional to the DC voltage, the harmonic distortion of the LED drive circuit is small.

[0039] The N+1th constant current circuit 13n+1 is respectively connected to the N+1th load 11n+1, the voltage divider circuit 101 and the current limiting component 14; the N+1th constant current circuit 13n+1 is also configured to control the output current so that the output current is proportional to the reference voltage when the reference voltage is greater than or equal to the clamping voltage of the Nth clamping circuit and the reference voltage is less than the upper limit voltage. The upper limit voltage is the peak value that the DC voltage of the reference voltage can reach under normal circumstances. Because the reference voltage is obtained by dividing the DC voltage, the waveform of the reference voltage is the same as the waveform of the DC voltage, and the output current of the N+1th constant current circuit 13n+1 is proportional to the wave of the reference voltage, so the output current of the N+1th constant current circuit 13n+1 is proportional to the DC voltage, so when the N+1th constant current circuit 13n+1 outputs, the harmonic distortion of the LED drive circuit is small.

[0040] The current limiting component 14 is configured to limit the output current of the constant current circuit.

[0041] like Figure 2 As shown, in one embodiment, N clamping circuits all include a clamping component, and the clamping component includes: a first operational amplifier U1, a second operational amplifier U2, a first field effect transistor Q1 and a first resistor R1; the non-inverting input terminal of the first operational amplifier U1 is the reference voltage input terminal of the clamping circuit; the non-inverting input terminal of the second operational amplifier U2 is the clamping voltage input terminal of the clamping circuit; the inverting input terminal of the first operational amplifier U1, the inverting input terminal of the second operational amplifier U2, the source of the first field effect transistor Q1 and the first end of the first resistor R1 together constitute the output end of the clamping circuit; the output end of the first operational amplifier U1 and the output end of the second operational amplifier U2 are commonly connected to the gate of the first field effect transistor Q1; the drain of the first field effect transistor Q1 is connected to the internal power supply; the second end of the first resistor R1 is connected to the power ground.

[0042] like Figure 3As shown, in one embodiment, N constant current circuits all include a constant current component, and the constant current component includes a third operational amplifier U3 and a second field effect transistor Q2; the non-inverting input terminal of the third operational amplifier U3 is the analog signal input terminal of the constant current component; the output terminal of the third operational amplifier U3 is connected to the gate of the second field effect transistor Q2; the negative phase input terminal of the third operational amplifier U3 and the source of the second field effect transistor Q2 together constitute the output current output terminal of the constant current component; the drain of the second field effect transistor Q2 is the input voltage input terminal of the constant current component.

[0043] like Figure 4 As shown, in one embodiment, the N+1th constant current circuit 13n+1 includes a fourth operational amplifier U4 and a third field effect transistor Q3; the non-inverting input terminal of the fourth operational amplifier U4 is the upper limit voltage input terminal of the N+1th constant current circuit 13n+1; the output terminal of the fourth operational amplifier U4 is connected to the gate of the third field effect transistor Q3; the negative phase input terminal of the fourth operational amplifier U4 and the source of the third field effect transistor Q3 together constitute the output current output terminal of the N+1th constant current circuit 13n+1; the drain of the third field effect transistor Q3 is the input voltage input terminal of the N+1th constant current circuit 13n+1.

[0044] like Figure 5 As shown, in one embodiment, the voltage divider circuit 101 includes a second resistor R2 and a third resistor R3, and the second end of the second resistor R2 and the first end of the third resistor R3 together constitute the output end of the voltage divider circuit 101; the first end of the second resistor R2 is the first input end of the DC voltage of the voltage divider circuit 101, and the second end of the third resistor R3 is the second input end of the DC voltage of the voltage divider circuit 101.

[0045] like Figure 6 As shown, in one embodiment, the high power factor and low harmonic LED driving circuit 1 further includes a rectifier circuit 105 , which is connected to the alternating current and is used to rectify the alternating current to generate a direct current voltage.

[0046] like Figure 7 As shown, in one embodiment, the rectifier circuit 105 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; the anode of the first diode D1 and the anode of the fourth diode D4 together constitute the second output end of the rectifier circuit 105, the cathode of the first diode D1 and the anode of the second diode D2 together constitute the first input end of the rectifier circuit 105, the cathode of the second diode D2 and the cathode of the third diode D3 together constitute the first output end of the rectifier circuit 105, and the anode of the third diode D3 and the cathode of the fourth diode D4 together constitute the second input end of the rectifier circuit 105.

[0047] The following is combined with the working principle Figure 8As shown in further explanation, Figure 7 The circuit schematic diagram of the LED driving circuit with high power factor and low harmonics when N is 2 is shown, that is, the LED driving circuit 1 with high power factor and low harmonics includes a rectifier circuit 105, a voltage divider circuit 101, an LED component 11, two clamping circuits, three constant current circuits and a current limiting component 14, and the current limiting component 14 is a resistor R4, wherein the LED component 11 includes a first light-emitting diode L1, a second light-emitting diode L2 and a third light-emitting diode L3; it should be noted that this embodiment does not limit the LED driving circuit 1 with high power factor and low harmonics, but is an exemplary description thereof, and it cannot be assumed that the N of the LED driving circuit 1 with high power factor and low harmonics can only be 2. The rectifier circuit 105 rectifies the alternating current to output a direct current voltage, and the second resistor R2 and the third resistor R3 divide the direct current voltage and output a reference voltage.

[0048] When the reference voltage is not greater than the clamping voltage of the first clamping circuit 121, the reference voltage is input to the positive phase input terminal of the first operational amplifier U1 of the first clamping circuit 121, and the clamping voltage V1 is input to the positive phase input terminal of the second operational amplifier U2. Because the negative phase input terminal of the first operational amplifier U1, the negative phase input terminal of the second operational amplifier U2, the source of the first field effect transistor Q1 and the first end of the first resistor R1 are connected in common, the first operational amplifier U1 outputs a high level to the gate of the first field effect transistor Q1, so that the first field effect transistor Q1 is turned on, so that the source of the first field effect transistor Q1 outputs an analog signal equal to the reference voltage to the positive phase input terminal of the third operational amplifier U3. Input terminal, therefore, the output terminal of the third operational amplifier U3 outputs a high level to the gate of the second field effect transistor Q2 of the first constant current circuit 131, so that the second field effect transistor Q2 of the first constant current circuit 131 is turned on. At the same time, because the negative phase input terminal of the third operational amplifier U3, the source of the second field effect transistor Q2 and the first end of the current limiting component 14 (the fourth resistor R4) are connected in common, the current flowing through the first light-emitting diode L1 is proportional to the analog signal, so that the current flowing through the first light-emitting diode L1 is proportional to the DC voltage. Therefore, when only the first light-emitting diode L1 is turned on, the output current of the LED driving circuit is proportional to the DC voltage, and the harmonic distortion is small.

[0049] When the reference voltage is greater than the clamping voltage of the first clamping circuit 121, and the reference voltage is not greater than the clamping voltage of the second clamping circuit 122, and because the voltage of the negative phase input terminal of the third operational amplifier U3 of the first clamping circuit 121 is greater than the positive phase input terminal, the output terminal of the third operational amplifier U3 of the first clamping circuit 121 outputs a low level, so that the second field effect transistor Q2 of the first constant current module 121 is turned off. At this time, the second clamping circuit 122 outputs an analog quantity equal to the reference voltage to the second constant current module 132, so that the second field effect transistor Q2 of the second constant current module 132 is turned on, so that the current flowing through the first light-emitting diode L1 and the second light-emitting diode L2 is proportional to the DC voltage. Therefore, when the first light-emitting diode L1 and the second light-emitting diode L2 are both turned on, the output current of the LED driving circuit is proportional to the DC voltage, and the harmonic distortion is small.

[0050] When the reference voltage is greater than the clamping voltage of the second clamping circuit 122, the voltage at the negative phase input terminal of the third operational amplifier U3 of the second clamping circuit 122 is greater than the voltage at the positive phase input terminal, and the output terminal of the third operational amplifier U3 of the second clamping circuit 122 outputs a low level so that the second field effect transistor Q2 of the second clamping circuit 122 is cut off, and at the same time, the fourth operational amplifier U4 outputs a high level to the third field effect transistor Q3, so that the third field effect transistor Q3 is turned on, so that the current flowing through the first light-emitting diode L1, the second light-emitting diode L2 and the third light-emitting diode L3 is proportional to the reference voltage, so that the current flowing through the first light-emitting diode L1, the second light-emitting diode L2 and the third light-emitting diode L3 is proportional to the DC voltage. Therefore, when the first light-emitting diode L1, the second light-emitting diode L2 and the third light-emitting diode L3 are all turned on, the output current and the DC voltage of the high power factor and low harmonic LED driving circuit 1 are also proportional, and the harmonic distortion is small. In summary, the waveforms of the output current and the DC voltage of the high power factor and low harmonic LED driving circuit 1 are as follows: Fig. 9 The waveform shown has less harmonic distortion.

[0051] An embodiment of the present invention further provides an LED device, which includes the high power factor and low harmonic LED driving circuit of any of the above embodiments. Because the LED device in this embodiment includes the high power factor and low harmonic LED driving circuit of any of the above embodiments, the LED device in this embodiment at least contains the beneficial effects corresponding to the high power factor and low harmonic LED driving circuit of any of the above embodiments.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high power factor and low harmonic LED driving circuit, characterized in that: The high power factor and low harmonic LED driving circuit comprises a voltage divider circuit, an LED component, N clamping circuits, N+1 constant current circuits and a current limiting component; The voltage divider circuit is configured to divide the DC voltage to generate a reference voltage when a DC voltage is connected; The LED assembly includes N+1 loads connected in series in sequence, the N+1 loads include a first load to an N+1th load, the positive electrode of the first load is connected to a DC voltage, and the negative electrode of the kth load is connected to the positive electrode of the k+1th load; wherein N is an integer greater than or equal to 1, and k is a positive integer less than or equal to N; an i-th clamping circuit, connected to the voltage divider circuit, configured to output an analog signal equal to the reference voltage when the reference voltage is less than the clamping voltage of the i-th clamping circuit and when the reference voltage is greater than or equal to the clamping voltage of the i-1-th clamping circuit; wherein i is a positive integer less than or equal to N; a jth constant current circuit, connected to the jth clamping circuit, the jth load, the j+1th load and the current limiting component, and configured to control the output current according to the analog signal so that the output current is proportional to the analog signal; wherein j is a positive integer less than or equal to N; an N+1th constant current circuit, connected to the N+1th load, the voltage divider circuit and the current limiting component, and configured to control the output current so that the output current is proportional to the reference voltage when the reference voltage is greater than or equal to the clamping voltage of the Nth clamping circuit and the reference voltage is less than an upper limit voltage; The current limiting component is configured to limit the output current of the constant current circuit; The voltage divider circuit comprises a second resistor and a third resistor, wherein the second end of the second resistor and the first end of the third resistor together constitute a reference voltage output end of the voltage divider circuit; the first end of the second resistor is a first DC voltage input end of the voltage divider circuit, and the second end of the third resistor is a second DC voltage input end of the voltage divider circuit; The high power factor and low harmonic LED driving circuit further includes: A rectifier circuit is connected to the AC power and used to rectify the AC power to generate a DC voltage.

2. The high power factor and low harmonic LED driving circuit according to claim 1, characterized in that: Each of the N clamping circuits includes a clamping component, wherein the clamping component includes a first operational amplifier, a second operational amplifier, a first field effect transistor, and a first resistor; The non-inverting input terminal of the first operational amplifier is the reference voltage input terminal of the clamp circuit, the non-inverting input terminal of the second operational amplifier is the clamp voltage input terminal of the clamp circuit, the inverting input terminal of the first operational amplifier, the inverting input terminal of the second operational amplifier, the source of the first field effect tube and the first end of the first resistor together constitute the output terminal of the clamp circuit, the output terminal of the first operational amplifier and the output terminal of the second operational amplifier are commonly connected to the gate of the first field effect tube, the drain of the first field effect tube is connected to the internal power supply, and the second end of the first resistor is connected to the power ground.

3. The high power factor and low harmonic LED driving circuit according to claim 1, characterized in that: Each of the N constant current circuits includes a constant current component, wherein the constant current component includes a third operational amplifier and a second field effect transistor; The non-inverting input terminal of the third operational amplifier is the analog signal input terminal of the constant current component, the output terminal of the third operational amplifier is connected to the gate of the second field effect tube, the negative phase input terminal of the third operational amplifier and the source of the second field effect tube together constitute the output current output terminal of the constant current component, and the drain of the second field effect tube is the input voltage input terminal of the constant current component; The N+1th constant current circuit includes a fourth operational amplifier and a third field effect transistor; The non-inverting input terminal of the fourth operational amplifier is the upper limit voltage input terminal of the N+1th constant current circuit, the output terminal of the fourth operational amplifier is connected to the gate of the third field effect transistor, the negative input terminal of the fourth operational amplifier and the source of the third field effect transistor together constitute the output current output terminal of the N+1th constant current circuit, and the drain of the third field effect transistor is the input voltage input terminal of the N+1th constant current circuit.

4. The high power factor and low harmonic LED driving circuit according to claim 1, characterized in that: The rectifier circuit includes a first diode, a second diode, a third diode and a fourth diode; the anode of the first diode and the anode of the fourth diode together constitute the second DC voltage output terminal of the rectifier circuit, the cathode of the first diode and the anode of the second diode together constitute the first AC input terminal of the rectifier circuit, the cathode of the second diode and the cathode of the third diode together constitute the first DC voltage output terminal of the rectifier circuit, and the anode of the third diode and the cathode of the fourth diode together constitute the second AC input terminal of the rectifier circuit.

5. An LED device, characterized in that: The invention comprises the high power factor and low harmonic LED driving circuit as claimed in any one of claims 1 to 4.

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