LED drive circuit and LED lighting device

Abstract

The utility model provides an LED driving circuit and an LED lighting device, and relates to the technical field of circuit design. The LED drive circuit comprises a control circuit, and an electromagnetic interference filter circuit, a rectification filter circuit and a valley fill circuit which are connected in sequence, wherein the input end of the electromagnetic interference filter circuit is connected with an alternating current power supply; the output end of the electromagnetic interference filter circuit is connected with the input end of the control circuit; the output end of the control circuit is connected with the valley filling circuit; the control circuit receives the input voltage output by the electromagnetic interference filter circuit; when the input voltage is greater than a first value, the control circuit outputs a first signal, and the first signal is used for controlling current to flow through a first resistor in the valley fill circuit; when the input voltage is smaller than the first value, the control circuit outputs a second signal which is used for controlling the current not to flow through the first resistor. Through the control circuit, the problem that the first resistor in the valley fill circuit is seriously heated during low-voltage input is solved.

Description

Technical Field

[0001] This application relates to the technical field of circuit design, and more specifically, to an LED driver circuit and an LED lighting device. Background Technology

[0002] Valley fill circuits utilize the valley fill circuits behind the rectifier bridge to significantly increase the conduction angle of the rectifier diodes. By filling the valley points, the input current changes from a spike pulse to a waveform close to a sine wave, thereby improving the power factor and reducing total harmonic distortion.

[0003] In related technologies, in order to meet the corresponding harmonic standards when the valley filling circuit is operating at high voltage, a large resistance value needs to be set for the damping resistor of the valley filling circuit; however, setting a large resistance value will cause the damping resistor to overheat severely when the valley filling circuit is operating at low voltage. Utility Model Content

[0004] This application addresses the shortcomings of existing methods by proposing an LED driver circuit and an LED lighting device to solve the technical problem of severe heat generation of the damping resistor during low-voltage operation of valley-filling circuits in related technologies.

[0005] In a first aspect, this application provides an LED driver circuit, comprising:

[0006] The control circuit and the electromagnetic interference filter circuit, rectifier filter circuit, and valley filling circuit connected in sequence;

[0007] The input terminal of the electromagnetic interference filtering circuit is connected to an AC power supply.

[0008] The output terminal of the electromagnetic interference filtering circuit is connected to the input terminal of the control circuit;

[0009] The output terminal of the control circuit is connected to the valley filling circuit;

[0010] The control circuit receives the input voltage output by the electromagnetic interference filter circuit;

[0011] When the input voltage is greater than a first value, the control circuit outputs a first signal, which is used to control the current to flow through the first resistor in the valley filling circuit;

[0012] When the input voltage is less than the first value, the control circuit outputs a second signal, which is used to control the current from flowing through the first resistor.

[0013] In one possible implementation, the control circuit includes: a voltage detection circuit;

[0014] The voltage detection circuit includes: a second resistor, a third resistor, a fourth resistor, and a first capacitor;

[0015] The first end of the second resistor serves as the input terminal of the voltage detection circuit and is connected to the electromagnetic interference filtering circuit; the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor, the first end of the first capacitor, and the first end of the fourth resistor are connected; the second end of the first capacitor and the second end of the fourth resistor are grounded.

[0016] In one possible implementation, the voltage detection circuit further includes: a first Zener diode, a first field-effect transistor, and an input terminal of an optocoupler, wherein the input terminal is a light-emitting diode;

[0017] The positive terminal of the first Zener diode is connected to the gate of the first field-effect transistor, and the negative terminal of the first Zener diode is connected to the first end of the fourth resistor; the drain of the first field-effect transistor is connected to the negative terminal of the light-emitting diode, and the source of the first field-effect transistor is grounded.

[0018] In one possible implementation, the control circuit further includes: a first resistor control module;

[0019] The first resistor control module includes an output terminal of an optocoupler and a second field-effect transistor; the output terminal is a phototransistor; the collector of the phototransistor is connected to the gate of the second field-effect transistor, the emitter of the phototransistor and the first end of the first resistor are connected to the source of the second field-effect transistor, and the second end of the first resistor is connected to the drain of the second field-effect transistor.

[0020] In one possible implementation, when the input voltage is greater than the first value, the first Zener diode is turned on, current flows through the gate of the first field-effect transistor, and the first field-effect transistor is turned on.

[0021] The light-emitting diode sends an optical signal to the phototransistor, and the phototransistor turns on.

[0022] When the gate-source voltage of the second field-effect transistor is less than the turn-on voltage, the second field-effect transistor is turned off, and the current flows through the first resistor of the valley-fill circuit.

[0023] In one possible implementation, when the input voltage is less than the first value, the first Zener diode is in the off state, the current does not pass through the gate of the first field-effect transistor, and the first field-effect transistor is in the off state.

[0024] The light-emitting diode does not send light signals to the phototransistor, and the phototransistor is cut off;

[0025] When the gate-source voltage of the second field-effect transistor is greater than the turn-on voltage, the second field-effect transistor is turned on, and the current flows through the source and drain of the second field-effect transistor, but does not flow through the first resistor of the valley-fill circuit.

[0026] In one possible implementation, the LED driving circuit further includes a flyback circuit;

[0027] The flyback circuit also includes a transformer, the primary winding of which includes a first coil, which is connected to the output terminal of the valley fill circuit.

[0028] In one possible implementation, the primary winding of the transformer further includes a second coil; and the LED driving circuit further includes a flyback circuit control module, the flyback circuit control module including a flyback circuit control chip, the flyback circuit control chip being connected to a first end of the second coil, and the second end of the second coil being grounded.

[0029] In one possible implementation, the LED driving circuit further includes an output module;

[0030] The output module includes an output filtering circuit and a signal feedback circuit.

[0031] The input terminal of the output filter circuit is connected to the flyback circuit, and the output terminal of the output filter circuit is connected to the input terminal of the signal feedback circuit.

[0032] The output of the signal feedback circuit is connected to the flyback circuit control module.

[0033] Secondly, this application provides an LED lighting device, including an LED module and an LED driving circuit as described in any one of the first aspects; the LED driving circuit is connected to the LED module.

[0034] The beneficial technical effects of the technical solution provided in this application include:

[0035] This application provides an LED driver circuit and an LED lighting device. The control circuit receives an input voltage output from an electromagnetic interference filter circuit. When the input voltage is greater than a first value, the control circuit outputs a first signal to control the current flow through a first resistor in the valley-fill circuit. When the input voltage is less than the first value, the control circuit outputs a second signal to control the current from flowing through the first resistor. This LED driver circuit controls the flow of the valley-fill current through the control circuit, ensuring that the valley-fill circuit passes harmonic standards while solving the problem of severe heat generation of the damping resistor when the valley-fill circuit operates at low voltage. This achieves the technical effect of low heat generation of the damping resistor while ensuring that the valley-fill circuit passes harmonic standards.

[0036] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0037] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0038] Figure 1 A schematic diagram of the framework of an LED driver circuit provided in this application;

[0039] Figure 2 A circuit diagram of an LED driver circuit provided in this application;

[0040] Figure 3 A circuit diagram of a control circuit, an electromagnetic interference filter circuit, a rectifier filter circuit, and a valley-filling circuit provided for this application;

[0041] Figure 4 A circuit diagram of a flyback circuit and a flyback circuit control module provided in this application;

[0042] Figure 5 A circuit diagram of an output rectifier circuit and a signal feedback circuit provided for this application;

[0043] Figure 6 This application provides a structural schematic diagram of an LED lighting device;

[0044] Figure label:

[0045] 10: Control circuit; 20: Electromagnetic interference filter circuit; 30: Rectifier filter circuit; 40: Valley fill circuit; 50: Flyback circuit; 60: Flyback circuit control module; 70: Output rectifier circuit; 80: Signal feedback circuit;

[0046] R39 - First resistor; R391 - First terminal of the first resistor; R392 - Second terminal of the first resistor;

[0047] R20 - Second resistor; R201 - First terminal of the second resistor; R202 - Second terminal of the second resistor;

[0048] R40 - Third resistor; R401 - First terminal of the third resistor; R402 - Second terminal of the third resistor;

[0049] R22 - Fourth resistor; R221 - First terminal of the fourth resistor; R222 - Second terminal of the fourth resistor;

[0050] R71 - First terminal of resistor R7; R72 - Second terminal of resistor R7; R81 - First terminal of resistor R8; R82 - Second terminal of resistor R8; R131 - First terminal of resistor R13; R132 - Second terminal of resistor R13; R141 - First terminal of resistor R14; R142 - Second terminal of resistor R14; R151 - First terminal of resistor R15; R152 - Second terminal of resistor R15; R161 - First terminal of resistor R16; R162 - Second terminal of resistor R16; R171 - First terminal of resistor R17; R172 - Second terminal of resistor R17; R301 - First terminal of resistor R30; R302 - Second terminal of resistor R30; R311 - First terminal of resistor R31; R312 - Second terminal of resistor R31;

[0051] C21 - First capacitor; C211 - First terminal of first capacitor; C212 - Second terminal of first capacitor; C51 - First terminal of capacitor C5; C52 - Second terminal of capacitor C5; C71 - First terminal of capacitor C7; C72 - Second terminal of capacitor C7; C81 - First terminal of capacitor C8; C82 - Second terminal of capacitor C8; C91 - First terminal of capacitor C9; C92 - Second terminal of capacitor C9; C191 - First terminal of capacitor C19; C192 - Second terminal of capacitor C19;

[0052] D10 - First Zener diode; Q1 - First field-effect transistor; Q5 - Second field-effect transistor;

[0053] U5A: Input terminal of the optocoupler; U5B: Output terminal of the optocoupler;

[0054] U3: Flyback circuit chip; T1: Transformer. Detailed Implementation

[0055] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0056] Those skilled in the art will understand that, unless specifically stated otherwise, the terms “comprising” and “the” used herein may also include plural forms. It should be further understood that the term “comprising” as used in the specification of this application means the presence of features, integers, steps, operations, elements, and / or components, but does not exclude other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by the art. It should be understood that when we say an element is “connected” or “coupled” to another element, the element may be directly connected or coupled to the other element, or it may mean that the element and the other element are connected through an intermediate element. Furthermore, “connected” or “coupled” as used herein may include wireless connection or wireless coupling. The term “and / or” as used herein means at least one of the items defined by the term; for example, “A and / or B” can be implemented as “A”, or as “B”, or as “A and B”.

[0057] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0058] Research has revealed that, in order to meet the corresponding harmonic standards when the valley filling circuit operates at high voltage, a large resistance value needs to be set for the damping resistor of the valley filling circuit; however, setting a large resistance value will cause the damping resistor to overheat severely when the valley filling circuit operates at low voltage.

[0059] The LED (Light Emitting Diode) driving circuit and LED lighting device provided in this application are intended to solve the above-mentioned technical problems in related technologies.

[0060] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0061] like Figure 1 and Figure 2As shown, the LED driving circuit includes: a control circuit 10, and an electromagnetic interference filter circuit 20, a rectifier filter circuit 30, and a valley filler circuit 40 connected in sequence; wherein, the input terminal of the electromagnetic interference filter circuit 20 is connected to an AC power supply; the output terminal of the electromagnetic interference filter circuit 20 is connected to the input terminal of the control circuit 10; the output terminal of the control circuit 10 is connected to the valley filler circuit 40; the control circuit 10 receives the input voltage output by the electromagnetic interference filter circuit 20; when the input voltage is greater than a first value, the control circuit 10 outputs a first signal, which is used to control the current to flow through the first resistor R39 in the valley filler circuit 40; when the input voltage is less than the first value, the control circuit 10 outputs a second signal, which is used to control the current not to flow through the first resistor R39.

[0062] Its working principle is that the control circuit 10 detects the input voltage of the electromagnetic interference filter circuit 20, and controls whether the current in the valley filling circuit 40 flows through the first resistor R39 according to the relationship between the input voltage and the first value, thereby ensuring that the valley filling circuit 40 passes the harmonic standard when working at high voltage, while the first resistor R39 heats up less when working at low voltage.

[0063] like Figure 1 , Figure 2 As shown, the LED driver circuit also includes a flyback circuit 50, a flyback circuit control module 60, an output rectifier circuit 70, and a signal feedback circuit 80. The input terminal of the flyback circuit 50 is connected to the output terminal of the valley fill circuit 40, the output terminal of the flyback circuit 50 is connected to the input terminal of the output rectifier circuit 70, the output terminal of the output rectifier circuit 70 is connected to the signal feedback circuit 80, the output terminal of the signal feedback circuit 80 is connected to the flyback circuit control module 60, and the output terminal of the flyback circuit control module 60 is connected to the flyback circuit 50. The output rectifier circuit 70 is used to output voltage to drive the LED lighting device. The signal feedback circuit 80 is used to generate a feedback signal based on the output voltage of the output rectifier circuit 70 and feeds the feedback signal back to the flyback circuit control module 60 through opto-isolation. The flyback circuit control module 60 adjusts the voltage output from the flyback circuit 50 to the output rectifier circuit 70 based on the received feedback signal.

[0064] like Figure 3As shown, the control circuit 10 includes a voltage detection circuit 110; wherein the voltage detection circuit 110 includes a second resistor R20, a third resistor R40, a fourth resistor R22, and a first capacitor C21; the first terminal R201 of the second resistor R20 serves as the input terminal of the voltage detection circuit and is connected to the electromagnetic interference filtering circuit; the second terminal R202 of the second resistor R20 is connected to the first terminal R401 of the third resistor R40, and the second terminal R402 of the third resistor R40, the first terminal C211 of the first capacitor C21, and the first terminal R221 of the fourth resistor R22 are connected; the second terminal C212 of the first capacitor C21 and the second terminal R222 of the fourth resistor R22 are grounded.

[0065] Specifically, in this application, the first terminal R201 of the second resistor R20 is connected to the electromagnetic interference filter circuit 20 as the input terminal of the voltage detection circuit; this allows the voltage signal after electromagnetic interference filtering to be received, thereby avoiding the influence of electromagnetic interference on the detection results; the first terminal R401 of the third resistor R40 is connected to the second terminal R202 of the second resistor R20, together forming part of the voltage divider circuit. Through the voltage divider effect, the circuit can reduce the input high voltage to a suitable detection range; the first terminal R221 of the fourth resistor R22, the first terminal C211 of the first capacitor C21, and the second terminal R402 of the third resistor R40 are connected to form an RC filter circuit. This filter circuit can further smooth the voltage signal and reduce the influence of voltage fluctuations on the detection results; at the same time, the first capacitor can also play the role of energy storage and voltage stabilization.

[0066] like Figure 3 As shown, in some optional embodiments, the voltage detection circuit further includes: a first Zener diode D10, a first field-effect transistor Q1, and the input terminal U5A of an optocoupler; the output terminal U5A is a light-emitting diode; wherein, the anode of the first Zener diode D10 is connected to the gate of the first field-effect transistor Q1, the cathode of the first Zener diode D10 is connected to the first terminal R221 of the fourth resistor R22; the drain of the first field-effect transistor Q1 is connected to the cathode of the input terminal U5A of the optocoupler, and the source of the first field-effect transistor Q1 is grounded.

[0067] Specifically, the anode of the first Zener diode D10 is connected to the gate of the first field-effect transistor Q1, and the cathode is connected to the first terminal R221 of the fourth resistor R22 (which is also the second terminal R402 of the third resistor R40 and the first terminal C211 of the first capacitor C21). When the voltage exceeds its regulated value, the first Zener diode D10 will break down and conduct, thereby protecting the subsequent circuit from overvoltage damage. The gate of the first field-effect transistor Q1 is connected to the anode of the first Zener diode D10, the drain is connected to the cathode of the light-emitting diode, and the source is grounded. In this application, the first field-effect transistor Q1 is used as a switching element, and its on / off state is controlled by the gate voltage. When the gate voltage reaches or exceeds the threshold voltage of the first field-effect transistor, the first field-effect transistor conducts, allowing current to flow; otherwise, it is off. The negative terminal of the light-emitting diode is connected to the drain of the first field-effect transistor. When the first field-effect transistor is turned on, the light-emitting diode lights up, generates a light signal, and sends the light signal to the output terminal U5B of the optocoupler, so that the output terminal U5B of the optocoupler is turned on.

[0068] like Figure 3 As shown, in some optional embodiments, the control circuit 10 further includes: a first resistor control module 120; wherein, the first resistor control module 120 includes the output terminal U5B of an optocoupler and a second field-effect transistor Q5; the output terminal U5B of the optocoupler is a phototransistor; the collector of the phototransistor is connected to the gate of the second field-effect transistor, the emitter of the phototransistor and the first terminal R391 of the first resistor R39 are connected to the source of the second field-effect transistor Q5, and the second terminal R392 of the first resistor R39 is connected to the drain of the second field-effect transistor Q5.

[0069] In practical applications, an optical coupler (OC), also known as an opto-isolator or simply optocoupler, is a device that uses light as a medium to transmit electrical signals. It typically encapsulates the transmitting end (infrared light-emitting diode, LED) and the receiving end (photosensitive semiconductor tube) within the same housing. When an electrical signal is applied to the transmitting unit of the optocoupler, the LED emits light; the receiving end receives this light and generates a photocurrent, which flows out from the output end, thus achieving an "electrical-to-optical-to-electrical" conversion.

[0070] In this application, the output terminal U5B of the optocoupler is a phototransistor. The collector of the phototransistor is connected to the gate of the second field-effect transistor Q5, and the emitter is connected to the first terminal R391 of the first resistor R39 and the source of the second field-effect transistor Q5. The phototransistor is used as an optoelectronic device, and its operating state is controlled by the received optical signal. When the intensity of the optical signal sent by the input terminal U5A of the optocoupler reaches or exceeds a preset threshold, the output terminal U5B of the optocoupler is turned on, thereby changing the gate voltage of the second field-effect transistor Q5. Further, the gate of the second field-effect transistor Q5 is connected to the collector of the output terminal U5B of the optocoupler, the source is connected to the emitter of the output terminal U5B of the optocoupler and the first terminal R391 of the first resistor R39, and the drain is connected to the second terminal R392 of the first resistor R39. The conduction state of the second field-effect transistor Q5 is controlled by the gate voltage.

[0071] like Figure 3 As shown, in some optional embodiments, when the input voltage is greater than a first value, the first Zener diode D10 is turned on, and current flows through the gate of the first field-effect transistor Q1, turning on the first field-effect transistor Q1; the input terminal U5A of the optocoupler sends an optical signal to the output terminal U5B of the optocoupler, turning on the output terminal U5B of the optocoupler; the gate-source voltage of the second field-effect transistor Q5 is less than the turn-on voltage, turning off the second field-effect transistor Q5, and current flows through the first resistor R39 of the valley-fill circuit 40.

[0072] Specifically, when the input voltage is greater than the first value, the voltage across the fourth resistor R22 is greater than the second value, the first Zener diode D10 is in the conducting state, and there is current input to the gate of the first field-effect transistor Q1. Therefore, the first field-effect transistor Q1 is also in the conducting state. In this case, the input terminal U5A of the optocoupler sends an optical signal to the output terminal U5B of the optocoupler. Due to the excitation of the optical signal, the output terminal U5B of the optocoupler is also in the conducting state. At this time, the gate and source of the second field-effect transistor Q5 are both connected to the first terminal R391 of the first resistor R39. Therefore, the voltages of the gate and source are the same, that is, the gate-source voltage is less than the conduction voltage. The second field-effect transistor Q5 is in the cut-off state, and the current cannot flow from the source to the drain of the second field-effect transistor Q5, but flows through the first resistor.

[0073] It should be noted that in this application, the first and second values ​​can be determined according to the actual situation.

[0074] like Figure 3As shown, in some optional embodiments, when the input voltage is less than a first value, the first Zener diode D10 is in the off state, the current does not pass through the gate of the first field-effect transistor Q1, and the first field-effect transistor Q1 is in the off state; the input terminal U5A of the optocoupler does not send an optical signal to the output terminal U5B of the optocoupler, and the output terminal U5B of the optocoupler is off; the gate-source voltage of the second field-effect transistor Q5 is greater than the turn-on voltage, the second field-effect transistor Q5 is turned on, and the current flows through the source and drain of the second field-effect transistor Q5, but does not flow through the first resistor R39 of the valley-fill circuit.

[0075] Specifically, when the input voltage is less than the first value, the voltage across the fourth resistor R22 is less than the second value. The cathode of the first Zener diode D10 is connected to the first terminal R221 of the fourth resistor R22. This can be understood as the voltage at the cathode of the first Zener diode D10 being the same as the voltage at the first terminal R221 of the fourth resistor R22. Since the second value is less than the reverse conduction voltage of the first Zener diode D10, the first Zener diode D10 is in the off state. There is no current input to the gate of the first field-effect transistor Q1, so the first field-effect transistor Q1 is also in the off state. In this case, the input terminal U5A of the optocoupler does not send an optical signal to the output terminal U5B of the optocoupler. Due to the lack of optical signal excitation, the output terminal U5B of the optocoupler is also in the off state, i.e., not conducting. Although the first field-effect transistor Q1 and the output terminal U5B of the optocoupler are both in the off state, the gate-source voltage of the second field-effect transistor Q5 is greater than its conduction voltage. Therefore, the second field-effect transistor Q5 is in the conducting state, and current can flow through its source and drain. Meanwhile, since the first resistor R39 is connected in parallel with the source and drain of the second field-effect transistor Q5, the current flows from the source to the drain of the second field-effect transistor Q5 and does not flow through the first resistor R39 of the valley-fill circuit 40. It can be understood that the second field-effect transistor Q5 provides a low-impedance path for the circuit when it is in the conducting state, so that the current flows through the source and drain of the second field-effect transistor Q5, instead of the first resistor R39.

[0076] like Figure 4 As shown, in some optional embodiments, the LED driving circuit further includes a flyback circuit 50;

[0077] The flyback circuit 50 is also equipped with a transformer T1. The primary winding of the transformer T1 includes a first coil, which is connected to the output terminal of the valley filling circuit 40.

[0078] Specifically, transformer T1 is provided with a primary winding, which includes a first coil, and the first end of the first coil ( Figure 2 The end of transformer T1 (marked by 1) is connected to the first end R131 of resistor R13, and the second end of the first coil ( Figure 2The first end of transformer T1 (marked by 2) is connected to the second end C52 of capacitor C5, and the second end R132 of resistor R13 is connected to the first end C51 of capacitor C5.

[0079] In this application, the valley filling circuit 40 improves the power factor of the circuit by adjusting the waveform of the input current to be closer to a sine wave, which helps to reduce harmonic pollution of the power grid and improve the efficiency of power utilization. At the same time, by adjusting the turns ratio of the first coil, the conversion between the input voltage and the output voltage can be realized to meet the voltage requirements of the LED lighting device.

[0080] See Figure 4 As shown, in some optional embodiments, the primary winding of transformer T1 further includes a second coil; and the LED driving circuit further includes a flyback circuit control module 60, which includes a flyback circuit control chip U3, which is connected to the first end of the second coil, and the second end of the second coil is grounded.

[0081] Specifically, the first end of the second coil ( Figure 2 One end of transformer T1 marked with 4) and the second end ( Figure 2 One end of the transformer T1 (marked by 5) is connected in parallel with capacitor C6, and the first end of the second coil is connected to the negative terminal of diode D2, the negative terminal of D6, and the first end R81 of resistor R8. The second end R82 of resistor R8 is connected to the DEM pin of flyback circuit control chip U3, and the second end of the second coil is grounded.

[0082] Specifically, the flyback circuit control module 60 also includes a switching transistor Q2; wherein, the gate of Q2 is connected to resistors R25 and R24, ferrite bead B1, and the GATE pin of the flyback circuit control chip; resistor R28 is connected in parallel with the gate and source of Q2; the drain of Q2 is connected to the anode of diode D7 and the second end of the first coil; the source of Q2 is connected to the bidirectional Zener diode D12 and then grounded; D12 is connected in parallel with resistors R27 and R29; furthermore, the FB pin of the flyback control chip is connected to the collector of the output terminal U1B of the optocoupler and the first terminal C171 of capacitor C17; the output terminal U1B of the optocoupler is used to receive the feedback signal sent by the input terminal U1A of the optocoupler, and controls the output voltage of the GATE pin of the flyback circuit control chip U3 according to the feedback signal, thereby controlling the on / off state of the switching transistor Q2, and thus realizing the control of the on / off state of the flyback circuit.

[0083] See Figure 5 As shown, in some optional embodiments, the LED driver circuit further includes an output module;

[0084] The output module includes an output filter circuit 70 and a signal feedback circuit 80.

[0085] The input terminal of the output filter circuit 70 is connected to the flyback circuit 50, and the output terminal of the output filter circuit 70 is connected to the input terminal of the signal feedback circuit 80.

[0086] The output of the signal feedback circuit 80 is connected to the flyback circuit control module 60.

[0087] Specifically, the output filter circuit 70 is connected to the secondary winding of the transformer T1 of the flyback circuit 50. The first and second ends of the secondary winding are the S end and the F end, respectively. The S end is connected to the capacitor C22, the first end C71 of the capacitor C7, the positive terminal of the diode D1, and the positive terminal of the diode D8. The second end C72 of the capacitor C7 is connected to the first end R151 of the resistor R15. The second end R152 of the resistor R15 is connected to the negative terminals of the diodes D1 and D8, the positive terminals of the polarized capacitors C10 and C11, the first end R171 of the resistor R17, and the V+ end. The F end is connected to the first end C81 of the capacitor C8, the first end C91 of the capacitor C9, the negative terminals of the polarized capacitors C10 and C11, and the second end R172 of the resistor R17. The second end C82 of the capacitor C8 is connected to the HV end, and the second end C92 of the capacitor C9 is grounded.

[0088] Specifically, the signal feedback circuit 80 includes the input terminal U1A of the optocoupler, capacitor C19, resistors R14, R16, resistors R30~R31, diode D9, and comparator U4; wherein, the first terminal R141 of R14, the cathode of diode D9, and the first terminal R161 of resistor R16 are connected to the output filter circuit 70; the second terminal R142 of resistor R14 and the first terminal R71 of resistor R7 are connected to the positive terminal U1A of the optocoupler. The negative terminal of the input terminal U1A of the electrocoupler, the second terminal R72 of resistor R7, the first terminal R301 of resistor R30, and pin 3 of comparator U4 are connected. The second terminal R302 of resistor R30 is connected to the first terminal C191 of capacitor C19. The second terminal C192 of capacitor C19 is connected to the second terminal R162 of resistor R16, the first terminal R311 of resistor R31, and pin 1 of comparator U4. Pin 2 of comparator U4 and the second terminal R312 of resistor R31 are grounded.

[0089] It should be noted that when the load voltage V+ output from the secondary winding is too high, the load voltage output from the secondary winding is divided by resistors R16 and R31. After voltage division, the voltage of resistor R31 is compared with the reference voltage of comparator U4. If it is greater than the reference voltage, comparator U4 conducts to form a loop, and the input terminal U1A of the optocoupler generates a feedback signal. The feedback signal is sent to the output terminal U1B of the optocoupler as an optical signal through opto-splitting. The output terminal U1B of the optocoupler converts the optical signal into an electrical signal and feeds the electrical signal back to the FB pin of the flyback circuit control chip U3. The flyback circuit control chip U3 controls the on / off state of the flyback circuit 50 through the switching transistor Q2, thereby adjusting the voltage value of the transformer output to the output filter circuit 70.

[0090] Based on the same inventive concept, this application provides an LED lighting device, including an LED module and an LED driving circuit provided in this application, wherein the LED driving circuit is connected to the LED module.

[0091] The LED driver circuit of this application controls the direction of the circuit in the valley filling current through the control circuit. While ensuring that the valley filling circuit passes the harmonic standard, it solves the problem of severe heating of the damping resistor when the valley filling circuit is working at low voltage. It achieves the technical effect of the valley filling circuit passing the harmonic standard without the damping resistor heating up.

[0092] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in related technologies that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0093] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0094] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0095] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0096] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0097] The above are only some embodiments of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of this application.

Claims

1. An LED driving circuit, characterized in that, include: The control circuit and the electromagnetic interference filter circuit, rectifier filter circuit, and valley filling circuit connected in sequence; The input terminal of the electromagnetic interference filtering circuit is connected to an AC power supply. The output terminal of the electromagnetic interference filtering circuit is connected to the input terminal of the control circuit; The output terminal of the control circuit is connected to the valley filling circuit; The control circuit receives the input voltage output by the electromagnetic interference filter circuit; When the input voltage is greater than a first value, the control circuit outputs a first signal, which is used to control the current to flow through the first resistor in the valley filling circuit; When the input voltage is less than the first value, the control circuit outputs a second signal, which is used to control the current from flowing through the first resistor.

2. The LED driving circuit according to claim 1, characterized in that, The control circuit includes: a voltage detection circuit; The voltage detection circuit includes: a second resistor, a third resistor, a fourth resistor, and a first capacitor; The first end of the second resistor serves as the input terminal of the voltage detection circuit and is connected to the electromagnetic interference filtering circuit; the second end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor, the first end of the first capacitor, and the first end of the fourth resistor are connected; the second end of the first capacitor and the second end of the fourth resistor are grounded.

3. The LED driving circuit according to claim 2, characterized in that, The voltage detection circuit further includes: a first Zener diode, a first field-effect transistor, and the input terminal of an optocoupler, wherein the input terminal is a light-emitting diode; The positive terminal of the first Zener diode is connected to the gate of the first field-effect transistor, and the negative terminal of the first Zener diode is connected to the first end of the fourth resistor; the drain of the first field-effect transistor is connected to the negative terminal of the light-emitting diode, and the source of the first field-effect transistor is grounded.

4. The LED driving circuit according to claim 3, characterized in that, The control circuit further includes: a first resistor control module; The first resistor control module includes an output terminal of an optocoupler and a second field-effect transistor; the output terminal is a phototransistor; the collector of the phototransistor is connected to the gate of the second field-effect transistor, the emitter of the phototransistor and the first end of the first resistor are connected to the source of the second field-effect transistor, and the second end of the first resistor is connected to the drain of the second field-effect transistor.

5. The LED driving circuit according to claim 4, characterized in that, When the input voltage is greater than the first value, the first Zener diode is turned on, and current flows through the gate of the first field-effect transistor, turning the first field-effect transistor on. The light-emitting diode sends an optical signal to the phototransistor, and the phototransistor turns on. When the gate-source voltage of the second field-effect transistor is less than the turn-on voltage, the second field-effect transistor is turned off, and the current flows through the first resistor of the valley-fill circuit.

6. The LED driving circuit according to claim 4, characterized in that, When the input voltage is less than the first value, the first Zener diode is in the off state, the current does not pass through the gate of the first field-effect transistor, and the first field-effect transistor is in the off state. The light-emitting diode does not send light signals to the phototransistor, and the phototransistor is cut off; When the gate-source voltage of the second field-effect transistor is greater than the turn-on voltage, the second field-effect transistor is turned on, and the current flows through the source and drain of the second field-effect transistor, but does not flow through the first resistor of the valley-fill circuit.

7. The LED driving circuit according to claim 1, characterized in that, The LED driving circuit also includes a flyback circuit; The flyback circuit also includes a transformer, the primary winding of which includes a first coil, which is connected to the output terminal of the valley fill circuit.

8. The LED driving circuit according to claim 7, characterized in that, The primary winding of the transformer also includes a second coil; and the LED driving circuit also includes a flyback circuit control module, which includes a flyback circuit control chip. The flyback circuit control chip is connected to the first end of the second coil, and the second end of the second coil is grounded.

9. The LED driving circuit according to claim 8, characterized in that, The LED driving circuit also includes an output module; The output module includes an output filtering circuit and a signal feedback circuit. The input terminal of the output filter circuit is connected to the flyback circuit, and the output terminal of the output filter circuit is connected to the input terminal of the signal feedback circuit. The output of the signal feedback circuit is connected to the flyback circuit control module.

10. An LED lighting device, characterized in that, It includes an LED module and an LED driving circuit according to any one of claims 1-9; the LED driving circuit is connected to the LED module.

Images