CN105451391B - A kind of LED drive circuit and light fixture - Google Patents

Abstract

The invention discloses a kind of LED drive circuit, including civil power, current rectifying and wave filtering circuit, drive circuit, output circuit and feedback circuit, wherein civil power is connected with current rectifying and wave filtering circuit, current rectifying and wave filtering circuit is connected with drive circuit, regulation circuit is provided between current rectifying and wave filtering circuit and drive circuit, the drive circuit other end is connected with output circuit and feedback circuit.The present invention between current rectifying and wave filtering circuit and drive circuit by increasing regulation circuit so that output voltage and electric current are stable, stroboscopic caused by so as to eliminate when LED drives.

Description

A kind of LED drive circuit and lamp

technical field

The invention relates to the technical field of lighting, in particular to an LED driving circuit and a lamp.

Background technique

With the development of science and technology, LED, as a new type of light source, has the advantages of small size, low power consumption, high light efficiency, long life, environmental protection, etc., and is widely used in the field of lighting, and various LEDs have emerged Driving circuit, in practical applications, the use of different LED driving circuits will have an impact on luminous efficiency and life.

At present, among many ways of driving LEDs, some use rectification and filtering circuits to directly connect with LED driving circuits to achieve efficient driving of LEDs. However, there are defects such as LED load flickering, easy damage, and strong high-frequency interference. caused inconvenience. In the application, the LED driving circuit needs to eliminate the stroboscopic problem caused by LED driving as much as possible.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides an LED drive circuit that can eliminate the stroboscopic problem caused by LED drive.

Technical solution: In order to achieve the above purpose, the present invention provides an LED drive circuit capable of eliminating the stroboscopic problem caused by driving, including a mains power supply, a rectification filter circuit, a drive circuit, an output circuit and a feedback circuit, wherein the mains power supply and the rectification filter circuit The circuit is connected, the rectification filter circuit is connected with the drive circuit, an adjustment circuit is arranged between the rectification filter circuit and the drive circuit, and the other end of the drive circuit is connected with the output circuit and the feedback circuit.

Further, the rectification filter circuit includes a piezoresistor R1, an inductor L1, an inductor L2, a resistor R2, a resistor R3, a capacitor C1 and a rectifier circuit, one end of the inductor L1 is connected to the live line L of the mains, and one end of the inductor L2 is connected to the mains The neutral line N of the electricity is connected, the other end of the inductor L1 and the inductor L2 are connected to the input end of the rectifier circuit, the two ends of the resistor R2 are respectively connected to the two ends of the inductor L1, and the two ends of the resistor R3 are respectively connected to the two ends of the inductor L2.

Further, the rectification circuit in the rectification and filtering circuit is a full-bridge rectification circuit.

Further, the drive circuit includes an inductor L3, a diode D2, a Zener diode D3, a diode D4, a Zener diode D5, a diode D6, a diode D7, a transformer T, a transistor Q3, a MOS transistor Q4 and a driver chip U1, wherein the inductor L3 One end of the inductance L3 is connected to the positive output end of the rectifier circuit, the other end of the inductance L3 is connected to the voltage input end VCC of the driver chip U1 after passing through the diode D4 and the resistor R14, and the other end of the inductance L3 is connected to the voltage input end VCC of the driver chip U1 through the primary winding of the transformer T and the diode D7. The output terminal DRV of the driver chip U1 is connected, the resistor R8 and the resistor R9 are connected in series, and one end is connected to the inductor L3, and the other end is connected to the collector of the transistor Q3, and the collector of the transistor Q3 is connected to the negative output terminal of the rectification filter circuit after being adjusted by the circuit. The connection point of the resistor R8 and the resistor R9 is connected to the anode of the diode D2 and the base of the transistor Q3, the other end of the diode D2 is respectively connected to the emitter of the transistor Q3, one end of the capacitor C2 and one end of the resistor R10, and the other end of the capacitor C2 It is connected to the collector of the transistor Q3, the other end of the resistor R10 is connected to the gate of the MOS transistor Q4, the source of the MOS transistor Q4 is connected to the collector of the transistor Q3, and the drain of the MOS transistor Q4 is connected to the gate of the transistor Q3 after passing through the resistor R11. The collector is connected, the anode of the Zener diode D5 is connected to the other end of the inductor L3, the cathode of the Zener diode D5 is connected to the cathode of the diode D6, and the anode of the diode D6 is connected to the output terminal DRV of the driver chip U1 after passing through the diode D7.

Further, the driving chip U1 includes a field effect transistor, wherein the drain of the field effect transistor is used as the output of the driving chip U1, and the source of the field effect transistor is connected to the drain of the MOS transistor Q4.

Further, the output circuit includes a Zener diode D8, a capacitor C6 and a resistor R19, the anode of the Zener diode D8 is connected to the positive end of the secondary winding of the transformer T, and the cathode of the Zener diode D8 is connected in series via a plurality of LEDs. The connected LED light strings are then connected to the negative terminal of the secondary winding of the transformer T.

Further, the feedback circuit includes a diode D9, a diode D10, a Zener diode D11 and a triode Q5, wherein the anode of the diode D9 is connected to the positive end of the auxiliary winding of the transformer T through a resistor R18, and the cathode of the diode D9 is connected to the triode Q5 through a resistor R15. The collector of Q5 is connected to the feedback terminal FB of the driver chip U1, the anode of the diode D10 is connected to the positive terminal of the auxiliary winding of the transformer T, the cathode of the diode D10 is connected to the cathode of the Zener diode D11 and one end of the capacitor C9, and the other end of the capacitor C9 One end is connected to the emitter of the transistor Q5, and the anode of the Zener diode D11 is connected to the base of the transistor Q5.

Further, the regulating circuit includes a MOS transistor Q1, a resistor R4, a resistor R5, a resistor R6 and a transistor Q2, wherein the drain of the MOS transistor Q1 is connected to the positive output terminal of the rectifier circuit, and the source of the MOS transistor Q1 passes through the resistor R4 It is connected to the negative output terminal of the rectifier circuit, one end of the resistor R5 is connected to the positive output terminal of the rectifier circuit, the other end of the resistor R5 is connected to the gate of the MOS transistor Q1 and the collector of the transistor Q2, and the emitter stage of the transistor Q2 is connected to the rectifier circuit The base of the transistor Q2 is connected to the negative output terminal of the rectifier circuit after passing through resistors R6 and R7, and one end of the voltage regulator tube D1 is connected to the gate of the MOS transistor Q1, and the other end is connected to the negative output terminal of the rectifier circuit , the connection point of the resistor R6 and the resistor R7 is connected to the collector of the triode Q3 in the drive circuit.

A lamp includes the above-mentioned LED driving circuit.

Compared with the prior art, the present invention has the advantages that: by adding a regulating circuit between the rectifying filter circuit and the driving circuit, the present invention makes the output voltage and current stable, thereby eliminating the flicker caused by LED driving.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a circuit structure diagram of the LED driving circuit of the present invention.

detailed description

The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments.

This embodiment provides a kind of LED drive circuit, as shown in Figure 1, mains 1, rectification and filter circuit 2, drive circuit 3, output circuit 4 and feedback circuit 5, it is characterized in that it also includes regulation circuit 6, and it is connected to rectifier Between the filter circuit 2 and the drive circuit 3 .

Fig. 2 shows the structure of the LED control circuit 3 of the LED drive circuit of the present invention, specifically:

The rectification filter circuit 2 includes a piezoresistor R1, an inductor L1, an inductor L2, a resistor R2, a resistor R3, a capacitor C1, and a rectifier circuit. One end of the inductor L1 and one end of the inductor L2 are respectively connected to the live line L and the neutral line N of the mains 1, The other end of the inductance L1 and the other end of the inductance L2 are connected to the input end of the rectification circuit, and the resistors R2 and R3 are respectively connected in parallel to the two ends of the inductance L1 and the inductance L2. The rectification circuit is a full-bridge rectification circuit.

The regulating circuit 6 includes a MOS transistor Q1, a resistor R4, a resistor R5, a resistor R6, and a triode Q2, wherein the drain of the MOS transistor Q1 is connected to the positive output terminal of the rectifier circuit, and the source of the MOS transistor Q1 is connected to the positive output terminal of the rectifier circuit after passing through the resistor R4. The negative output terminal of the output terminal, one terminal of the resistor R5 is connected to the positive output terminal of the rectifier circuit, the other terminal of the resistor R5 is connected to the gate of the MOS transistor Q1 and the collector of the transistor Q2, and the emitter of the transistor Q2 is connected to the negative output terminal of the rectifier circuit, The base of the transistor Q2 is connected to the negative output terminal of the rectifier circuit through the resistor R6 and the resistor R7, and the regulator D1 is connected between the gate of the MOS transistor Q1 and the negative output terminal of the rectifier circuit, and the connection point of the resistor R6 and the resistor R7 It is connected with the collector of the triode Q3 in the driving circuit 3 .

The drive circuit 3 includes an inductor L3, a diode D2, a voltage regulator diode D3, a diode D4, a voltage regulator diode D5, a diode D6, a diode D7, a transformer T, a triode Q3, a MOS transistor Q4, and a driver chip U1, wherein one end of the inductor L3 is connected to a rectifier The positive output terminal of the circuit, the other end is connected to the voltage input terminal VCC of the driver chip U1 after the diode D4 and the resistor R4, the other end of the inductor L3 is connected to the output terminal DRV of the driver chip U1 after the primary winding of the transformer T, the diode D7, and the resistor R8 and resistor R9 are connected in series between the other end of inductor L3 and the collector of transistor Q3. The collector of transistor Q3 is connected to the negative output terminal of rectifier filter circuit 2 after regulating circuit 6. The connection point of resistor R8 and resistor R9 Connect the anode of the diode D2 and the base of the transistor Q3, the other end of the diode D2 is respectively connected to the emitter of the transistor Q3, one end of the capacitor C2, one end of the resistor R10, the other end of the capacitor C2 is connected to the collector of the transistor Q3, and the resistor R10 The other end is connected to the gate of the MOS transistor Q4, the source of the MOS transistor Q4 is connected to the collector of the transistor Q3, the drain of the MOS transistor Q4 is connected to the collector of the transistor Q3 through the resistor R11, and the anode of the Zener diode D5 is connected to the inductor L3 At the other end, the cathode of the Zener diode D5 is connected to the cathode of the diode D6, and the anode of the diode D6 is connected to the output terminal DRV of the driver chip U1 after passing through the diode D7. The driver chip U1 includes a field effect transistor, wherein the drain of the field effect transistor As the output of the driving chip U1, the source of the field effect transistor is connected to the drain of the MOS transistor Q4.

The output circuit 4 includes a Zener diode D8, a capacitor C6, and a resistor R19. The anode of the Zener diode D8 is connected to the positive end of the secondary winding of the transformer T, and the cathode of the Zener diode D8 is connected in series through a plurality of LED lights. Then connect the negative end of the secondary winding of the transformer T.

The feedback circuit 5 includes a diode D9, a diode D10, a Zener diode D11, and a transistor Q5, wherein the anode of the diode D9 is connected to the positive terminal of the auxiliary winding of the transformer T through a resistor R18, and the cathode of the diode D9 is connected to the collector of the transistor Q5 through a resistor R15 and The feedback terminal FB of the driver chip U1, the anode of the diode D10 is connected to the positive terminal of the auxiliary winding of the transformer T, and its cathode is connected to the cathode of the Zener diode D11 and one end of the capacitor C9, and the other end of the capacitor C9 is connected to the emitter of the triode Q5. The anode of the diode D11 is connected to the base of the transistor Q5.

Since the adjustment circuit 6 is added between the rectification filter circuit 2 and the drive circuit 3, the adjustment circuit 6 senses the output voltage through the resistor R6, thereby controlling the turn-on and turn-off of the transistor Q2, and the turn-on and turn-off of the transistor Q2 further controls the MOS The turn-on and turn-off of the tube Q1 adjusts the output of the circuit through the turn-on and turn-off of the MOS tube, and the Zener diode R4 protects the MOS tube Q1. The addition of the regulating circuit 6 can eliminate the LED load stroboscopic problem caused when the rectifying and filtering circuit 2 is directly connected to the driving circuit 3 .

The present invention further provides a lamp, which includes an LED lamp string and the LED driving circuit shown in FIGS. 1-2 , wherein the LED lamp string includes at least two LED lamps.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. All modifications should be included within the protection scope of the present invention.

Claims (8)

1. a kind of LED drive circuit, including civil power, current rectifying and wave filtering circuit, drive circuit, output circuit and feedback circuit, it is special Sign is：Regulation circuit is provided between civil power and current rectifying and wave filtering circuit, current rectifying and wave filtering circuit is connected with drive circuit, driving electricity The road other end is connected with output circuit and feedback circuit；The drive circuit includes inductance L3, diode D2, voltage-regulator diode D3, diode D4, voltage-regulator diode D5, diode D6, diode D7, transformer T, triode Q3, metal-oxide-semiconductor Q4 and driving chip U1, the wherein positive output end of inductance L3 one end and rectification circuit are connected, and the inductance L3 other end passes through diode D4 and resistance It is connected after R14 with driving chip U1 voltage input end VCC, armature winding and two poles of the inductance L3 other end through transformer T It is connected after pipe D7 with driving chip U1 output end DRV, one end is connected the other end with inductance L3 after resistance R8 connects with resistance R9 It is connected with triode Q3 colelctor electrode, the negative output terminal after the triode Q3 adjusted circuit of colelctor electrode with current rectifying and wave filtering circuit connects Connect, resistance R8 is connected with resistance R9 tie point with the base stage of diode D2 positive pole and triode Q3, and diode D2's is another One end of one end emitting stage with triode Q3, electric capacity C2 one end and resistance R10 respectively is connected, the electric capacity C2 other end and three Pole pipe Q3 colelctor electrode connection, the resistance R10 other end are connected with metal-oxide-semiconductor Q4 grid, metal-oxide-semiconductor Q4 source electrode and triode Q3 Colelctor electrode connection, the colelctor electrode of metal-oxide-semiconductor Q4 drain electrode with triode Q3 after resistance R11 is connected, voltage-regulator diode D5's Anode is connected with the inductance L3 other end, and voltage-regulator diode D5 negative electrode is connected with diode D6 negative electrode, diode D6 sun Output end DRV connections of the diode D7 after driving chip U1 is passed through in pole.

A kind of 2. LED drive circuit according to claim 1, it is characterised in that：The current rectifying and wave filtering circuit includes pressure-sensitive Resistance R1, inductance L1, inductance L2, resistance R2, resistance R3, electric capacity C1 and rectification circuit, inductance L1 one end and the live wire L of civil power Connection, inductance L2 one end and the zero line N connections of civil power, the input of inductance L1 and inductance the L2 other end and rectification circuit connect Connect, resistance R2 both ends connect respectively at inductance L1 both ends, and resistance R3 both ends connect respectively at inductance L2 both ends.

A kind of 3. LED drive circuit according to claim 2, it is characterised in that：Rectification in the current rectifying and wave filtering circuit Circuit is full bridge rectifier.

A kind of 4. LED drive circuit according to claim 1, it is characterised in that：The driving chip U1 includes field effect Output of Ying Guan, wherein the FET drain electrode as driving chip U1, the source electrode of FET connect with metal-oxide-semiconductor Q4 drain electrode Connect.

A kind of 5. LED drive circuit according to claim 1, it is characterised in that：The output circuit includes the pole of voltage stabilizing two Pipe D8, electric capacity C6 and resistance R19, voltage-regulator diode D8 anode are connected with the anode of transformer T secondary windings, voltage-regulator diode Negative terminal of the D8 negative electrode with transformer T secondary windings after the LED string that multiple LEDs are serially connected is connected.

A kind of 6. LED drive circuit according to claim 1, it is characterised in that：The feedback circuit include diode D9, Diode D10, voltage-regulator diode D11 and triode Q5, wherein diode D9 anode aid in by resistance R18 and transformer T The anode connection of winding, diode D9 negative electrode are anti-with triode Q5 colelctor electrode and driving chip U1 after resistance R15 End FB connections are presented, diode D10 anode is connected with the anode of transformer T assists windings, diode D10 negative electrode and voltage stabilizing two Pole pipe D11 negative electrode is connected with electric capacity C9 one end, and the electric capacity C9 other end is connected with triode Q5 emitting stage, the pole of voltage stabilizing two Pipe D11 anode is connected with triode Q5 base stage.

A kind of 7. LED drive circuit according to claim 3, it is characterised in that：It is described regulation circuit include metal-oxide-semiconductor Q1, Resistance R4, resistance R5, resistance R6 and triode Q2, the wherein positive output end of metal-oxide-semiconductor Q1 drain electrode and rectification circuit are connected, MOS Pipe Q1 source electrode is connected after resistance R4 with the negative output terminal of rectification circuit, resistance R5 one end and the positive output of rectification circuit End connection, the resistance R5 other end is connected with the colelctor electrode of metal-oxide-semiconductor Q1 grid and triode Q2, triode Q2 emitting stage and The negative output terminal connection of rectification circuit, the negative output terminal of triode Q2 base stage after resistance R6, resistance R7 with rectification circuit Connection, the other end is connected with metal-oxide-semiconductor Q1 grid for voltage-stabiliser tube D1 one end and the negative output terminal of rectification circuit connects, resistance R6 and electricity Resistance R7 tie point is connected with triode Q3 colelctor electrodes in drive circuit.

A kind of 8. light fixture, it is characterised in that：The light fixture includes the LED drive circuit as described in claim any one of 1-7.