KR101078988B1 - Light emitting diode driving circuit - Google Patents

Abstract

A rectifier configured as a bridge diode to convert an AC input into a pulse current; An inductor charged or stepped down by the output power of the rectifier or discharged by a switching transistor described below; A controller for outputting a switching pulse such that the power output through the smoothing circuit is maintained at a constant magnitude regardless of load variation; A switching transistor configured to receive and switch a switching pulse of the controller to charge or discharge a current in the inductor; A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal; A filter circuit for removing switch noise and electromagnetic waves caused by the switching operation of the switching transistor; An overcurrent protection circuit configured to switch according to a control signal of the controller to prevent overcurrent from being transmitted to the light emitting diode (LED) module; And a protection circuit connected between the smoothing circuit and the control unit and the load terminal in series and in parallel to remove reverse voltage, signal noise, impact voltage, external pulse, etc. flowing from the load terminal to the power supply terminal. Diode driver circuit.

Description

Light emitting diode driving circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode driver circuit, and more particularly, to a light emitting diode driver circuit having a protection circuit for protecting a power supply terminal from a reverse voltage or noise flowing from a load end of a light emitting diode module used as an illumination device. It is about.

Lighting devices for converting electrical energy into light energy include incandescent lamps, fluorescent lamps or halogen lamps, and they are selectively used according to their purpose.Incandescent lamps convert heat energy into light energy when electric energy is applied to the filament inside the glass tube. It is a structure that consumes power, and a fluorescent lamp is composed of a discharge tube. When electrical energy is applied to both electrodes, each atom and electron in the discharge tube scatter and emit light to the phosphor.

The incandescent lamp consumes heat energy even after switching the switch on and off for a short time, so there is no big difference in power consumption. There is a problem that the airborne, which has to change the lighting often because the holding, life is very short. Fluorescent lamps are easy to purchase and are most commonly used in ordinary homes.However, disadvantages include high heat when used for a long time such as incandescent lamps, and their lifespan is relatively longer than incandescent lamps (4,000 to 8,000 hours), but they are frequently switched on and off. If you do, the life of about 1 hour is reduced at a time, there is an inconvenience to replace the fluorescent lamp frequently.

On the other hand, the lighting device using a light emitting diode (Light Emitting Diode) is attracting attention as a long time, low maintenance cost, and low power consumption with high reliability compared to existing lighting fixtures.

The light emitting diode is a semiconductor device that generates a small number of carriers (electrons or holes) injected using a PN junction structure of a semiconductor and emits light energy by recombination thereof. Has high luminous efficiency because it converts directly into light energy, it is widely used in display lamps of various kinds of electronic devices such as display devices of automobile instruments, light sources for optical communication, numeral / letter / figure display devices, lighting devices, card readers, backlights of liquid crystal displays, etc. It is used.

Due to these advantages, light emitting diode modules in which a plurality of light emitting diodes are arranged in series or in parallel are widely used for lighting or various display devices. In particular, recently, input power and output brightness of the light emitting diode modules have been increased, and thus they are used in various areas.

However, as the light emitting diode illumination device is gradually changed to a high output, a reverse voltage, reverse current, or noise may be introduced from the light emitting diode load end to the power supply end, which causes the driver circuit of the light emitting diode to be damaged or in a transient state. This causes problems such as a fire.

An object of the present invention is to provide a light emitting diode driver circuit capable of protecting a non-insulating semiconductor integrated circuit for light emitting diode operation control.

Another object of the present invention is to provide a light emitting diode driver circuit capable of blocking reverse voltage, reverse current, or noise flowing from a power supply stage from a load stage.

Still another object of the present invention is to provide a light emitting diode driver circuit capable of exhibiting a load efficiency of 80% or more when the light emitting diode lamp is operated.

The light emitting diode driver circuit according to the present invention comprises a rectifying unit which is composed of a bridge diode to convert an AC input into a pulse current; An inductor configured to be charged by the output power of the rectifier or discharged by the following switching transistor to step up / down the output power; A controller for outputting a switching pulse such that the power output through the smoothing circuit is maintained at a constant magnitude regardless of load variation; A switching transistor configured to receive and switch a switching pulse of the controller to charge or discharge a current in the inductor; A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal; A filter circuit for removing switch noise and electromagnetic waves during the switching operation of the switching transistor; An overcurrent protection circuit which is switched according to a control signal of the controller to prevent overcurrent from being transmitted to the light emitting diode (LED) module; A zener diode connected in series between the inductor and the smoothing circuit, a first varistor connected between the zener diode and a ground line, one end of which is connected between the first varistor and the smoothing circuit, and the other end of the overcurrent protection circuit and the controller A second varistor connected between the third and second varistors connected between the overvoltage detection signal input terminal and the ground line of the controller and one end of the second varistor connected between the second varistor and the controller and the other end of which is connected to the ground line. And a protection circuit for removing reverse voltage, signal noise, impact voltage, external pulses, etc. flowing into the power supply terminal from the lower end.

Another feature of the LED driver circuit according to the present invention is that the first, third and fourth varistors are of the same specification and the allowable voltage is larger than the allowable voltage of the second varistor.

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A further feature of the LED driver circuit according to the present invention is that the first, second, third and fourth varistors block overvoltage or noise greater than 30V from the load stage to the power stage. .

Another feature of the light emitting diode driver circuit according to the present invention is to drive a high brightness light emitting diode of 3 ~ 24V using an input voltage of 9 ~ 16V.

The light emitting diode driver circuit according to the present invention has the following effects.

First, the reverse voltage or the reverse current is introduced from the load stage to the power stage to prevent the circuit from being damaged.

Secondly, the LED lighting device can be protected from the reverse voltage of the load stage.

Third, it is possible to protect a variety of equipment drawn from the power supply terminal and the distribution panel from the reverse voltage of the load terminal.

1 is a view schematically showing the configuration of a lighting apparatus using a light emitting diode according to the present invention.
2 is a circuit diagram showing the configuration of a light emitting diode driver circuit according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms "... part", "... group", "module", "block", etc. described in the specification mean a unit that processes at least one function or operation.

1 is a view schematically showing the configuration of a lighting apparatus using a light emitting diode according to the present invention. As shown, the driver circuit 1 receives an alternating current (AC) voltage to control a group of light emitting diodes consisting of a plurality of light emitting diodes (LD1, LD2, ... LDn), the light emitting diode group in series with the driver circuit. A set of light emitting diodes LD1, LD2,... LDn connected to each other and composed of light emitting diodes of the same or different colors. The light emitting diode driver circuit according to the present invention It is a driver configuration circuit for using the light emitting diode driven by the output voltage of 3 ~ 24V by using the input voltage DC 9 ~ 16V and is applicable to high brightness light emitting diode by using the Boost-buck circuit.

2 is a circuit diagram showing the configuration of a light emitting diode driver circuit according to the present invention. As shown, the light emitting diode driver circuit according to the present invention includes a bridge diode (BD) to be rectified by the rectifying unit 10 for rectifying the input power, and the output power of the rectifying unit 10 or the following switching An inductor L1 discharged by a transistor to boost / step down the output power, a smoothing circuit 20 for directing and directing the DC power up or down through the inductor L1 to the load end, and the smoothing The control unit 40 outputs a switching pulse so that the power output through the circuit 20 is maintained at a constant magnitude regardless of the load variation, and receives and switches the switching pulse of the control unit 40 to charge or induce current in the inductor. A switching transistor (Q1) for discharging, a filter circuit (30) for removing switch noise and electromagnetic waves due to the switching operation of the switching transistor (Q1); An overcurrent protection circuit 50 which is switched according to a control signal of the controller 40 to prevent an overcurrent from being transmitted to the light emitting diode module; The zener diode ZD1 and the first, second, third and fourth varistors VX1, VX2, VX3 and VX4 are connected in series or in parallel between the smoothing circuit 20, the controller 40 and the load terminal. It includes a protection circuit 100 to remove the reverse voltage, signal noise, impact voltage, external pulses, etc. flowing into the power supply terminal from the light emitting diode module side, and using a DC 9 ~ 16V of 3 ~ 24V A high brightness light emitting diode driven by an output voltage can be used.

The rectifier 10 includes a plurality of capacitors C1 and C2 connected in parallel including a bridge diode to full-wave rectify AC input power and output a pulse current power.

The inductor L1 connected in parallel to the capacitor C2 temporarily charges the current by the pulsating power output from the rectifier 10, and discharges the current charged by the switching of the switching transistor Q1 to the rectifier. The output power of (10) is boosted and stepped down and supplied to the smoothing circuit 20.

The smoothing circuit 20 includes a diode D1 rectifying the pulsed power passed through the inductor L1, and capacitors C10 and C11 for smoothing and directing the power rectified by the diode D1. It is done by

The switching transistor Q1 includes a field effect transistor (FET) having a drain terminal connected to the inductor L1 and a gate terminal connected to the controller 40. The resistors R11 and R12 connected to the source terminal of the switching transistor Q1 serve to stabilize the switching operation of the switching transistor Q1.

The controller 40 applies a pulse signal to the gate terminal of the switching transistor Q1 to control the switching of the switching transistor Q1 such that a constant voltage or a constant current is supplied to the light emitting diode through the smoothing circuit 20, The pulse width of the pulse signal applied to the gate terminal of the switching transistor Q1 is modulated by a pulse width modulation signal.

A resistor R3 is connected to the synchronization signal input terminal SYNC of the controller 40, a resistor R6 and a capacitor C9 are connected to the feedback signal input terminal FDBK and the comparison signal input terminal COMPP to the capacitor C8. Side by side are connected in parallel, and the resistors R7 and R8 are connected in parallel to the clamping signal input terminal CLM. The pulse required for the switching operation of the switching transistor Q1 is output through the gain control output terminal GAT of the controller 40.

In the filter circuit 30, capacitors C4, C5, and C6 connected in parallel to each other are connected in series between the inductor L1 and the coil L2, and noise and electromagnetic waves due to the switching operation of the switching transistor Q1 are performed. Remove it.

The overcurrent protection circuit 50 includes resistors R1 and R2 and a capacitor C3 connected to a load, a switching transistor Q2 receiving a control signal from the control unit 40 through a gate terminal, and the switching transistor ( A resistor R13 and R14 and a capacitor C12 connected to the source terminal of Q2) and a diode D2 connected to the drain terminal and the load terminal of the switching transistor Q2 are included.

The resistors R1 and R2 and the capacitor C3 are connected between the output terminal of the smoothing unit 20 and the load terminal formed of the light emitting diode module to sense the magnitude of the current output through the light emitting diode module to control the controller 40. ) Is transmitted to the overvoltage detection signal input terminal (OVP). Accordingly, the switching transistor Q2 is turned off by the control signal output through the operation blocking signal output terminal FAULT of the controller 40. The resistors R13 and R14 stabilize the switching operation of the switching transistor Q2, and the capacitor C12 serves to compensate for gain in a high frequency band, and the voltage applied to the resistor R13 is controlled by the controller 40. The control unit 40 controls the pulse width of the pulse signal applied to the switching transistor Q1 by using the feedback signal.

The protection circuit 100 may include a zener diode ZD1 connected in series between the inductor L1 and the smoothing circuit 20, a first varistor VX1 connected between the zener diode ZD1 and a ground line; One end is connected between the first varistor VX1 and the smoothing circuit, and the other end is connected to the second varistor VX2 connected between the overcurrent protection circuit 50 and the controller 40 and the overvoltage of the controller 40. A third varistor VX3 connected between the sensing signal input terminal OVP and a ground line; One end is formed between the second varistor (VX2) and the control unit 40 and the other end comprises a fourth varistor (VX4) connected to the ground line.

The varistors (VX1, VX2, VX3, VX4) are classified into symmetric varistors whose resistance is determined by the magnitude of the voltage, and asymmetric varistors varying by the polarity of the voltage applied, regardless of the polarity of the applied voltage. It is used to protect the light emitting diode driver circuit from surge voltage.

The zener diode ZD1 blocks the reverse voltage flowing through the smoothing circuit 20 from the load terminal to the control unit 40 or the switching transistor Q1, and the first varistor VX1 is configured as the zener diode ZD1) to induce a reverse voltage or a reverse current to the ground, the second varistor (VX2) is a reverse voltage or reverse current flowing through the smoothing circuit 20 from the load terminal to the control unit 40 It blocks the transmission. On the other hand, the third varistor (VX3) is that the reverse voltage, reverse current, noise, shock voltage or external pulse flowing from the load terminal through the resistor (R1) is transmitted to the overvoltage detection signal input terminal (OVP) of the controller 40 The fourth varistor VX4 has a reverse voltage, a reverse current, a noise, an impact voltage, or an external pulse that is not blocked by the second varistor VX2. Block FAULT).

The first, third, and fourth varistors (VX1, VX3, VX4) have the same specification (05D560K) and its allowable voltage is 35 V AC and 45 V DC, allowing the second varistor (VX2) (05D470K). Voltage is greater than AC 30V, DC 38V. Therefore, the reverse voltage which is not blocked by the second varistor VX2 may be prevented from being transmitted to the controller 40.

The protection circuit 100 protects the light emitting diode driver circuit by blocking a predetermined voltage and a specific current in order to remove a reverse voltage or a current of 30V or more flowing back from the load end to the power supply end, and ultimately the lighting device using the light emitting diode Of course, it is possible to protect the various devices that are drawn in from the power supply terminal and the distribution panel, and the input and output can remove the risk factors such as the circuit is broken by the voltage, current or external noise, or the fire occurs according to the transient state. When a short, noise, or the like is introduced from the light emitting diode lighting device, that is, the load end circuit portion, the power supply terminal is operated by the operation of the plurality of varistors VX1, VX2, VX3, and VX4 and the zener diode ZD1. It can remove the reverse voltage or current, and when the LED lighting device is operated, it can have a load efficiency of 80% or more.

In the above description of the present invention, a light emitting diode driver circuit having a specific structure has been described with reference to the accompanying drawings. However, the present invention may be variously modified and changed by those skilled in the art, and such modifications and changes are intended to protect the present invention. Should be interpreted as being within the scope.

1: light emitting diode driver circuit 10: rectifier
20: smoothing circuit 30: filter circuit
40: control unit 50: overcurrent protection circuit
100: protection circuit

Claims (6)

A rectifier configured as a bridge diode to convert an AC input into a pulse current;
An inductor charged or stepped down by the output power of the rectifier or discharged by a switching transistor described below;
A control unit for outputting a switching pulse so that the power output through the smoothing circuit is maintained at a constant size regardless of load variation;
A switching transistor configured to receive and switch a switching pulse of the controller to charge or discharge a current in the inductor;
A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal;
A filter circuit for removing switch noise and electromagnetic waves caused by the switching operation of the switching transistor;
An overcurrent protection circuit configured to switch according to a control signal of the controller to prevent overcurrent from being transmitted to the light emitting diode module;
A zener diode connected in series between the inductor and the smoothing circuit, a first varistor connected between the zener diode and a ground line, one end of which is connected between the first varistor and the smoothing circuit, and the other end of the overcurrent protection circuit and the controller A second varistor connected between the third and second varistors connected between the overvoltage detection signal input terminal and the ground line of the controller and one end of the second varistor connected between the second varistor and the controller and the other end of which is connected to the ground line. A light emitting diode driver circuit having a protection circuit for removing any one of a reverse voltage, a signal noise, an impact voltage, an external pulse flowing into the power supply terminal from the lower end. delete 2. The light emitting diode driver circuit of claim 1, wherein the allowable voltages of the first, third and fourth varistors are larger than the allowable voltages of the second varistors. 4. The light emitting diode driver circuit according to claim 3, wherein the first, third and fourth varistors are devices of the same standard. 5. The light emitting diode driver circuit according to claim 3 or 4, wherein the first, second, third and fourth varistors block reverse voltage greater than 30V from entering the control unit from the load terminal. The light emitting diode driver circuit of claim 1, wherein the light emitting diode driver circuit drives a high luminance light emitting diode of 3 to 24V using an input voltage of 9 to 16V.

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