KR101078973B1 - Light emitting diode driving circuit - Google Patents

Abstract

A rectifier configured as a bridge diode to rectify the input power; An inductor configured to be charged by the output power of the rectifier or discharged by the following switching transistor to boost or step down the output power; A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal; 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 feedback unit for transmitting the magnitude of power supplied to the light emitting diode module to the controller; And a protection circuit connected to the smoothing circuit in series to remove the reverse voltage flowing from the load end to the power supply end.

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.

Because of 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.

A light emitting diode driver circuit according to the present invention comprises a rectifier configured to rectify the input power source is composed of a bridge diode; An inductor configured to be charged by the output power of the rectifier or discharged by the following switching transistor to boost or step down the output power; A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal; 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 feedback unit for transmitting the magnitude of power supplied to the light emitting diode module to the controller; It is connected to the smoothing circuit in series characterized in that it comprises a protection circuit for removing the reverse voltage flowing from the load end to the power supply end.

Another feature of a light emitting diode driver circuit according to the present invention is a zener diode in which the protection circuit is connected in series between the smoothing circuit and the load terminal; A first varistor having one end connected between the smoothing circuit and the zener diode and the other end grounded; A second varistor having one end connected between the operation voltage input terminal and the load terminal of the controller and the other end grounded; And a third varistor having one end connected to the zener diode and the other end connected to the feedback unit.

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

Another feature of the LED driver circuit according to the present invention is that the first and second varistors are devices of the same standard.

Another feature of the LED driver circuit according to the present invention is that the LED driver circuit drives a high brightness LED having an output of 40 W using an input voltage of 9 to 25 V.

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 a light emitting diode that can display an output of 40W by using an input voltage of DC 9 ~ 25V. It is a circuit that can be applied to a high brightness light emitting diode using a 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 feedback unit 30 for transmitting the magnitude of power supplied to the light emitting diode module to the control unit 40, and the smoothing circuit 20 in series. It includes a protection circuit 100 is connected to remove the reverse voltage flowing from the load stage to the power stage, it can drive a high-brightness LED having an output of 40W using an input voltage of 9 ~ 25V.

The rectifier 10 includes a plurality of capacitors C1, C2, and C3 connected in parallel including a bridge diode, a resistor R4 connected in series to the capacitor C2, and a parallel connection to the resistor R4. The resistors R1 and R3 and a diode D1 connected in parallel to the capacitor C3 are provided to full-wave rectify AC input power to output a pulse current power. The resistor R4 detects a waveform of an output voltage and performs a role of a synchronization resistor for transmitting the waveform to the controller 40.

The smoothing circuit 20 is made of a capacitor (C4) to smooth the direct current of the pulsating current flow rectified by the rectifier 10.

The inductor L1 connected in series with the diode D1 temporarily charges the current by the pulse current power output from the rectifier 10, and discharges the current charged by the switching of the switching transistor Q1. The output power of (10) is boosted and stepped down and supplied to the smoothing circuit 20.

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 control unit 40 applies a pulse signal to the gate terminal of the switching transistor Q1 through a resistor R5 so that a constant voltage or a constant current is supplied to the light emitting diode through the smoothing circuit 20. Controlling the switching of the signal and modulating the pulse width of the signal applied to the gate terminal of the switching transistor Q1 by a pulse width modulation signal for dimming.

The dimming control signals d1 and d2 are transmitted to the controller 40 to change the color of the light emitting diode and the size of the output. The capacitor C8 connected to the controller 40 provides a signal that is a reference for the switching operation of the controller 40.

The feedback unit 30 includes a zener diode D4 and a plurality of resistors R9, R10, and R11 connected in parallel to the capacitor C6, and controls the size of the power supplied to the light emitting diode module. The control unit 40 controls the pulse width of the pulse signal applied to the switching transistor Q1 by using the signal fed back to the control unit 40.

The protection circuit 100 includes a zener diode ZD1 connected in series between a capacitor C4 constituting the smoothing circuit 20 and a load terminal, and one end thereof between the capacitor C4 and the zener diode ZD1. A first varistor VX1 connected to the other end and grounded, and a second varistor having one end connected between the operating voltage lead terminal Vin and the load terminal of the controller 40 through a resistor R2 and the other end grounded. VX2) and a third varistor VX3 having one end connected between the zener diode ZD1 and the coil L2 and the other end connected to the feedback unit.

The varistors (VX1, VX2, VX3) are classified into symmetric varistors whose resistance is determined by the magnitude of the voltage, and asymmetric varistors varying by the polarity of the applied voltage, 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 from the load terminal from being transmitted to the control unit 40 or the switching transistor Q1 through the smoothing circuit 20, and the first varistor VX1 is configured as the zener diode ZD1) serves to induce a reverse voltage or reverse current that is not blocked by the ground, and the second varistor VX2 flows in through the resistor R7 of the feedback unit 30 and the diode D2. It serves to block the voltage or reverse current from being transmitted to the controller 40 or the switching transistor Q1. On the other hand, the third varistor (VX3) serves to block the reverse voltage or reverse current transmitted to the controller 40 through the resistor (R9, R10) of the feedback unit 30 via the coil (L2).

The first and second varistors VX1 and VX2 have the same standard (05D560K) and allowable voltages are AC 35V and DC 45V, and allowable voltages AC 30V and DC of the third varistor VX3 (05D470K). Greater than 38V

The protection circuit 100 protects the light emitting diode driver circuit by blocking a predetermined voltage and a specific current to remove the voltage and current flowing back from the load end to the power supply end, and ultimately the lighting device using the light emitting diode as well as the power supply end and It is possible to protect various equipments coming in from the distribution board, and the input / output can remove the risk factors such as the circuit breakdown or the fire due to the transient state due to voltage, current or external noise. When a short, noise, or the like is introduced from the light emitting diode lighting device, that is, the load end circuit part, the current flows back to the power supply stage by the operation of the plurality of varistors VX1, VX2, and VX3 and the zener diode ZD1. The voltage or current can be removed, and when the LED lighting apparatus 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.

10: rectifier 20: smoothing circuit
30: feedback unit 40: control unit
100: light emitting diode driver circuit

Claims (5)

A rectifier configured as a bridge diode to rectify the input power;
An inductor configured to be charged by the output power of the rectifier or discharged by the following switching transistor to boost or step down the output power;
A smoothing circuit for smoothing the DC power up or down through the inductor and directing the DC power to the load terminal;
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 feedback unit for transmitting the magnitude of power supplied to the light emitting diode module to the controller;
And a protection circuit connected in series with the smoothing circuit to remove a reverse voltage flowing from the load end to the power supply end. The method of claim 1, wherein the protection circuit,
A zener diode connected in series between the smoothing circuit and the load terminal;
A first varistor having one end connected between the smoothing circuit and the zener diode and the other end grounded;
A second varistor having one end connected between the operation voltage input terminal and the load terminal of the controller and the other end grounded;
And a third varistor having one end connected to the zener diode and the other end connected to a feedback part. 3. The light emitting diode driver circuit according to claim 2, wherein an allowable voltage of the first and second varistors is larger than an allowable voltage of the third varistor. 4. The light emitting diode driver circuit according to claim 3, wherein the first and second varistors are devices of the same standard. The light emitting diode driver circuit of claim 1, wherein the light emitting diode driver circuit drives a high brightness light emitting diode having an output of 40 W using an input voltage of 9 to 25V.

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