CN201174804Y - An isolated general lighting LED drive circuit - Google Patents

Abstract

The utility model belongs to the field of electronic technology and relates to a general lighting LED drive circuit. The utility model comprises an input rectification circuit, a power factor correction (PFC) control circuit, a transformer surge current and peak voltage absorption circuit, an optocoupler isolation feedback circuit, an isolation switch transformer and a one-way rectification output circuit. The utility model uses ON Semiconductor's power management chip NCP1653 as the control core to detect the primary current of the switching transformer to realize the power factor correction function; the circuit topology is flyback and isolation, the working mode is continuous conduction mode, and has power factor correction , Dimming, constant current regulated output and absorbing the inrush current of the switching element at the moment of turning on and the function of the peak voltage at the moment of turning off. At the same time, because the utility model adopts the power management chip NCP1653, a large number of peripheral circuits can be saved, so it has the advantages of low cost and small volume, and is suitable for mass production.

Description

An isolated general lighting LED drive circuit

technical field

The utility model belongs to the field of electronic technology, and relates to a general lighting LED (light emitting diode) driving circuit, in particular to an isolated high-reliability lighting LED driving circuit.

Background technique

LED lighting technology has the advantages of energy saving, environmental protection, long life and easy control. It is one of the most promising high-tech fields in the 21st century. It will replace incandescent lamps and fluorescent lamps and become the leading lighting market. Under such a bright prospect of the LED lighting industry, various LED lamp driving circuits are also developing rapidly for different applications in the lighting field, and most of them adopt switching power supply technology. However, many LED drive circuits currently use non-isolated drive structures or isolated drive structures without power factor correction (PFC) functions. Non-isolated LED drive circuits have poor reliability, and LED drive circuits without PFC functions have low power utilization. . In addition, for the isolated circuit structure, due to the existence of the isolation transformer, a large inrush current will be generated when the switching element is turned on, and a large peak voltage will be generated at the moment of turning off, which will affect the power supply efficiency and the life of the switch tube. The absorption circuit of the existing isolated switching power supply at the moment when the switching element is turned off is relatively mature, but there are few absorption circuits when the switching element is turned on. The instantaneous surge current becomes a technical problem.

Utility model content

The utility model overcomes the deficiency of the existing LED drive circuit and provides an isolated high-performance general lighting LED drive circuit. The circuit has the characteristics of high reliability of the isolated LED drive circuit, and has power factor correction function and dimming function at the same time. And it has the function of surge absorption at the instant of switching element opening and closing.

The detailed technical scheme of the utility model is as follows:

An isolated general lighting LED drive circuit, which consists of an input rectifier circuit, a dimming control circuit, a power factor correction (PFC, Power Factor Correction) control circuit, a transformer surge current and peak voltage absorption circuit, an optocoupler isolation feedback circuit, an isolation Composed of a switching transformer and a unidirectional rectification output circuit, it is characterized in that:

The dimming control circuit is composed of diode D8 and capacitor C11; the power factor correction control circuit is composed of resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R11, R12, diode D1, capacitors C1, C2, The PFC control module circuit composed of C3, C4, C5 and ON Semiconductor's power management chip NCP1653 and the NCP1653 start-up circuit composed of resistor R10, diode D2 and capacitor C9; the transformer surge current and peak voltage absorption circuit is composed of diode D4 , D5, capacitor C6, inductors L1, L2; the optocoupler isolation feedback circuit is composed of resistors R13, R14, R15, R16, R17, R18, capacitor C8, transistor Q2, three-terminal device TL431 and optocoupler isolators U2A, U2B; The unidirectional rectification output circuit is composed of transformer secondary winding, diode D6, inductor L3, capacitors C7, C10 and light-emitting diodes LED1, LED2, ..., LED19, LED20 as loads;

The output terminal A of the AC mains rectified by the rectification circuit is connected to the terminal C of the primary winding of the isolated switching transformer T1, the output terminal B of the rectification circuit is grounded to GND, and the two output terminals A and B are connected through a capacitor C1; PWM dimming The signal is connected to the negative pole of the diode D8, the positive pole of the diode D8 is connected to the pin 2 of the power management chip NCP1653, the negative pole of the diode D8 is connected to the pin 6 of the chip NCP1653 through the capacitor C11, which is also the GND_IC of the chip, and the positive pole of the diode D8 is connected to the chip through the capacitor C4 Ground GND_IC; pin 3 of the power management chip NCP1653 is connected to the chip ground GND_IC through the capacitor C3 on the one hand, and connected to the port C of the primary winding of the isolated switching transformer T1 through the resistor R2 and the resistor R1 on the other hand, and the resistor R1 and the resistor R2 The connection point is connected to the chip ground GND_IC through the capacitor C2; the pin 4 of the power management chip NCP1653 is grounded to GND through the resistor R5; the pin 5 of the power management chip NCP1653 is connected to the chip ground GND_IC through the parallel circuit of the resistor R9 and the capacitor C5; the power management chip Pin 6 of the NCP1653 is connected to the chip ground GND_IC; the chip ground GND_IC is connected to the ground GND through a resistor R7; the pin 7 of the power management chip NCP1653 is connected to the gate of the MOS switch Q1 through the resistor R11, and the gate of the MOS switch Q1 At the same time, the resistor R12 is connected to the chip ground GND_IC, the source of the MOS switch tube Q1 is connected to the chip ground GND_IC, and the drain of the MOS switch tube Q1 is connected to the port D of the primary winding of the isolated switching transformer T1 through the inductor L2; the pin of the power management chip NCP1653 8 On the one hand, connect the GND_IC of the chip through the capacitor C9, on the other hand, connect the cathode of the diode D2 and the diode D3 and the collector of the controlled part of the optocoupler isolator U2B at the same time, and connect the anode of the diode D2 to the primary winding of the isolated switching transformer T1 through the resistor R10 Port C, the emitter of the controlled part U2B of the optocoupler isolator is connected to the anode of the diode D1 through the resistor R6, and at the same time connected to the chip ground GND_IC through the resistor R3, and the cathode of the diode D1 is connected to the pin 1 of the power management chip NCP1653 through the resistor R4; The pin 1 of the power management chip NCP1653 is also connected to the pin 8 of the power management chip NCP1653 through the resistor R4 and the resistor R8 in turn; the anode of the diode D3 is connected to the port E of the feedback winding of the isolated switching transformer T1, and the terminal of the feedback winding of the isolated switching transformer T1 Port F is connected to the chip ground GND_IC; port C of the primary winding of the isolated switching transformer T1 is connected to the negative pole of the diode D4, and the positive pole of the diode D4 is connected to the port D of the primary winding of the isolated switching transformer T1 through the capacitor C6; the positive pole of the diode D4 is connected through the inductor L1 The cathode of diode D5 is connected to the cathode, and the anode of diode D5 is connected to the chip ground GND_IC; the port G of the secondary winding of the isolated switching transformer T1 is connected to the anode of diode D6, and the port H is connected to the output ground GND_out; on the one hand, the cathode of diode D6 is connected to The output ground GND_out, on the other hand, is connected to the output ground GND_out through the inductor L3 and the capacitor C7 in turn; the connection point of the inductor L3 and the capacitor C7 is connected to the output ground GND_out through the resistor R17 and the resistor R18 on the one hand, and connected to the light through the resistor R15 on the other hand. The positive pole of the control part U2A of the coupler isolator; the negative pole of the control part U2A of the optocoupler isolator is connected to the collector of the transistor Q2 and the negative pole of the three-terminal device TL431 at the same time, and the resistor R16 is connected in parallel with the control part of the optocoupler isolator U2A; the three-terminal device TL431 The anode of the triode is connected to the output ground GND_out, the control pole of the three-terminal device TL431 is connected to the connection point of the resistor R17 and the resistor R18; the emitter of the transistor Q2 is connected to the output ground GND_out, and the base of the transistor Q2 is connected to the collector of the transistor Q2 through the capacitor C8 on the one hand. Connected, on the other hand through the resistor R14, resistor R13 and then connected to the output ground GND_out;

When the entire isolated general lighting LED drive circuit is working, the positive terminal connected in series with the connection point of the inductance L3 and the resistor R15, and the negative terminal connected with the resistor R13 and the resistor R13 and the resistor Connection point for R14.

The utility model has the following characteristics:

1. The power management chip NCP1653 of ON Semiconductor is used as the control core to detect the primary current of the switching transformer T1 to realize power factor correction.

2. The topology of the circuit is an isolated flyback (FlyBack) circuit, and the working mode is continuous conduction mode (CCM, Continuous Current Mode).

3. The dimming control circuit is composed of diode D8 and capacitor C11, which can adjust the brightness of LED with PWM wave, so it has dimming function.

4. The isolated feedback circuit is composed of resistors R13, R14, R15, R16, R17, R18, capacitor C8, transistor Q2, three-terminal device TL431 and optocoupler isolator (U2A, U2B) to ensure constant current regulated output and realize over current and LED open circuit protection.

5. The transformer surge current and peak voltage absorbing circuit is composed of diodes D4, D5, capacitor C6, inductors L1, L2, and has the function of absorbing the surge current and peak voltage at the moment of turning on the switching element.

In summary, the isolated general lighting LED driver circuit of the present invention has the functions of power factor correction, dimming, cross-current regulated output, and absorption of surge current at the moment of turn-on and peak voltage at the moment of turn-off of the switching element. At the same time, because the present invention adopts the power management chip NCP1653, a large number of peripheral circuits can be saved, so it has the advantages of low cost and small volume, and is suitable for mass production.

Description of drawings

Fig. 1 is a circuit diagram of the utility model.

Detailed ways

As shown in Figure 1, the circuit is mainly composed of NCP1653, isolated switching transformer T1, surge absorbing circuit (diode D4, D5, capacitor C6, inductor L1, L2), optocoupler isolator (U2A, U2B) and resistors, capacitors, NCP1653 The CS pin (the 4th pin) detects the current of the branch to change the pulse width to realize PFC. The diode D4, D4, D5, inductor L1, and capacitor C6 absorb the peak voltage generated at the moment the switch tube is turned off, and the inductor L2 absorbs The surge current generated at the moment the switch tube is turned on, the FB pin (the first pin) of the NCP1653 detects the feedback signal of the optocoupler isolator, and realizes the output overcurrent and LED open circuit protection functions, the V _control pin (the second pin) of the NCP1653 Pin) is connected to the PWM control signal through the diode D8 to realize the LED dimming function.

Claims (1)

1, a kind of insulation type general use illumination LED driving circuit, absorb circuit, light-coupled isolation feedback circuit, isolated switch transformer and unidirectional rectifying output circuit by input rectification circuit, adjusting control circuit, Active PFC control circuit, transformer inrush current and peak voltage and form, it is characterized in that:

Adjusting control circuit is made of diode D8 and capacitor C 11; The Active PFC control circuit comprises PFC control module circuit that the power management chip NCP1653 by resistance R 1, R2, R3, R4, R5, R6, R7, R8, R9, R11, R12, diode D1, capacitor C 1, C2, C3, C4, C5 and ON company constitutes and the start-up circuit of the NCP1653 that is made of resistance R 10, diode D2, capacitor C 9 is formed; Transformer inrush current and peak voltage absorb circuit and are made of diode D4, D5, capacitor C 6, inductance L 1, L2; The light-coupled isolation feedback circuit is made of resistance R 13, R14, R15, R16, R17, R18, capacitor C 8, triode Q2, three terminal device TL431 and optical coupling isolator U2A, U2B; Unidirectional rectifying output circuit by transformer secondary output winding, diode D6, inductance L 3, capacitor C 7, C10 and as the LED 1 of load, LED2 ..., LED19, LED20 form;

The output terminals A of electric main after the rectification circuit rectification meets the port C of the elementary winding of isolated switch transformer T1, and the output B ground connection GND of rectification circuit links to each other by capacitor C 1 between two output terminals A, the B; The PWM dim signal connects the negative pole of diode D8, the positive pole of diode D8 connects the pin two of power management chip NCP1653, the negative pole of diode D8 connects the pin 6 of chip NCP1653 by capacitor C 11, also is chip ground GND_IC, and the positive pole of diode D8 meets chip ground GND_IC by capacitor C 4; The pin 3 of power management chip NCP1653 meets chip ground GND_IC by capacitor C 3 on the one hand, successively by meeting the port C of the elementary winding of isolated switch transformer T1 after resistance R 2 and the resistance R 1, the tie point of resistance R 1 and resistance R 2 meets chip ground GND_IC by capacitor C 2 on the other hand; The pin 4 of power management chip NCP1653 is by resistance R 5 ground connection GND; Meet chip ground GND_IC behind the parallel circuits of the pin 5 of power management chip NCP1653 by resistance R 9 and capacitor C 5; The pin 6 of power management chip NCP1653 meets chip ground GND_IC; Link to each other by resistance R 7 between chip ground GND_IC and the ground GND; The pin 7 of power management chip NCP1653 connects the grid of MOS switching tube Q1 by resistance R 11, the grid of MOS switching tube Q1 meets chip ground GND_IC by resistance R 12 simultaneously, the source electrode of MOS switching tube Q1 meets chip ground GND_IC, and the drain electrode of MOS switching tube Q1 meets the port D of the elementary winding of isolated switch transformer T1 by inductance L 2; The pin 8 of power management chip NCP1653 meets chip ground GND_IC by capacitor C 9 on the one hand, connect the negative pole of diode D2, diode D3 and the collector electrode of the controlled part U2B of optical coupling isolator on the other hand simultaneously, the positive pole of diode D2 meets the port C of the elementary winding of isolated switch transformer T1 by resistance R 10, meet chip ground GND_IC by resistance R 3 when the emitter of the controlled part U2B of optical coupling isolator connects the positive pole of diode D1 by resistance R 6, the negative pole of diode D1 connects the pin one of power management chip NCP1653 by resistance R 4; The pin one of power management chip NCP1653 also connects the pin 8 of power management chip NCP1653 successively by resistance R 4, resistance R 8; The positive pole of diode D3 meets the port E of isolated switch transformer T1 feedback winding, and the port F of isolated switch transformer T1 feedback winding meets chip ground GND_IC; The port C of the elementary winding of isolated switch transformer T1 connects the negative pole of diode D4, and the positive pole of diode D4 links to each other with the port D of the elementary winding of isolated switch transformer T1 by capacitor C 6; The positive pole of diode D4 links to each other by the negative pole that inductance L 1 meets diode D5, and the positive pole of diode D5 meets chip ground GND_IC; The port G of isolated switch transformer T1 secondary winding connects the positive pole of diode D6, and port H meets output ground GND_out; The negative pole of diode D6 meets output ground GND_out by capacitor C 10 on the one hand, on the other hand successively by meeting output ground GND_out after inductance L 3, the capacitor C 7; The tie point of inductance L 3 and capacitor C 7 meets output ground GND_out by resistance R 17, resistance R 18 on the one hand successively, connects the positive pole of optical coupling isolator control section U2A on the other hand by resistance R 15; The negative pole of optical coupling isolator control section U2A connects the collector electrode of triode Q2 and the negative pole of triode TL431 simultaneously, and resistance R 16 is in parallel with optical coupling isolator control section U2A; The positive pole of three terminal device TL431 connects output ground GND_out, the control utmost point connecting resistance R17 of three terminal device TL431 and the tie point of resistance R 18; The emitter of triode Q2 meets output ground GND_out, and the base stage of triode Q2 links to each other with the collector electrode of triode Q2 by capacitor C 8 on the one hand, on the other hand successively by meeting output ground GND_out after resistance R 14, the resistance R 13;

Whole isolated formula general illumination LED drive circuit when work, as LED for illumination LED1, the LED2 of load ... the positive termination inductance L 3 after LED19 and the LED20 series connection and the tie point of resistance R 15, the tie point of negative terminal connecting resistance R13 and resistance R 14.

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