CN103687139A - LED driver - Google Patents

Abstract

The invention discloses an LED drive device which is applicable to driving a plurality of LED units, wherein the LED units are connected in parallel. The LED drive device comprises a voltage conversion unit, a plurality of detection units, a protection unit and a control unit, wherein the voltage conversion unit is used for receiving working voltage, converting the working voltage into an output voltage according to a control signal, and outputting the output voltage to the anode taps of the LED units; the detection units are coupled with the cathode taps of the LED units respectively and used for generating a plurality of detection signals; the protection unit is coupled with the detection units and used for receiving the detection signals and correspondingly generating a protection signal according to the detection signals; the control unit is coupled with the protection unit and the voltage conversion unit and used for receiving the protection signal and generating a control signal according to the protection signal.

Description

LED driver

technical field

The invention relates to a driving device, in particular to a light emitting diode driving device.

Background technique

Light Emitting Diodes (LEDs) have advantages such as long life, small size, high shock resistance, low heat generation, and low power consumption, so they have been widely used as indicators or light sources in household and various equipment. In recent years, light-emitting diodes have developed towards multi-color and high brightness, so their application fields have been extended to large outdoor signage, traffic signal lights and related lighting fields. In the future, light-emitting diodes may become the main lighting source with both power saving and environmental protection functions.

For the driving method of light emitting diodes, most of them convert the AC voltage into DC voltage or current first, and then use the stable DC voltage or current to drive the light emitting diodes to work and emit light. Moreover, most of the electrical or electronic products currently provide power from the mains, and most of these electrical or electronic products contain conductors such as metals for power transmission.

However, due to some external factors, such as lightning, electromagnetic interference (Electromagnetic Interference, EMI), electromagnetic compatibility (Electromagnetic Compatibility, EMC), surge current or power supply misconnection, etc., the LED driving circuit will make the driving of the LED The current increases. Once the driving current exceeds the rated value of the LED, it will easily lead to damage or shorten the life of the LED. Therefore, there is still room for improvement in the LED driving circuit, so as to effectively prevent LED products from being damaged due to factors such as over-current, over-voltage, and wrong connection of power sources.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a light emitting diode driving device, so as to achieve the protection function of over-current, over-voltage and wrong connection of power supply.

A light emitting diode driving device disclosed in the present invention is suitable for driving a plurality of light emitting diode units, wherein the light emitting diode units are connected in parallel. The LED driving device includes a voltage conversion unit, a plurality of detection units, a protection unit and a control unit. The voltage conversion unit receives the operating voltage, converts the operating voltage into an output voltage according to the control signal, and outputs the output voltage to the anode terminal of the LED unit. The aforementioned detection units are respectively coupled to the cathode terminals of the LED units for generating a plurality of detection signals. The protection unit is coupled to the detection unit for receiving the detection signal and correspondingly generating a protection signal. The control unit is coupled to the protection unit and the voltage conversion unit for receiving the protection signal and generating a control signal accordingly.

In an embodiment, the aforementioned voltage conversion unit includes a first resistor, a first capacitor, a transformer, a first diode, a first switch unit and a second diode. The first resistor has a first terminal and a second terminal. The first end of the first resistor receives the working voltage. The first capacitor has a first terminal and a second terminal. The first terminal of the first capacitor is coupled to the first terminal of the first resistor, and the second terminal of the first capacitor is coupled to the second terminal of the first resistor. The transformer has a primary side and a secondary side. The first terminal of the primary side of the transformer is coupled to the first terminal of the first resistor, and the second terminal of the secondary side of the transformer is coupled to the ground terminal. The first diode has a first end and a second end, the cathode end of the first diode is coupled to the second end of the first resistor, and the anode end of the first diode is coupled to the second end of the primary side of the transformer . The first switch unit has a first terminal, a second terminal and a third terminal, the first terminal of the first switch unit is coupled to the anode terminal of the first diode, the second terminal of the first switch unit is coupled to the ground terminal, and the second terminal of the first switch unit is coupled to the ground terminal. A third terminal of a switch unit receives a control signal. The second diode has a first end and a second end, the anode end of the second diode is coupled to the first end of the secondary side of the transformer, and the cathode end of the second diode generates an output voltage.

In an embodiment, each of the aforementioned detection units includes a second resistor. The second resistor has a first terminal and a second terminal, the first terminal of the second resistor is coupled to the cathode terminal of the corresponding LED unit to generate a detection signal, and the second terminal of the second resistor is coupled to the ground terminal.

In an embodiment, the aforementioned protection unit includes a plurality of protection circuits. The protection circuits are respectively one-to-one coupled to the detection units for receiving corresponding detection signals and correspondingly generating protection signals.

In an embodiment, each of the protection circuits includes a third resistor, a second capacitor, a fourth resistor, a comparison unit, a fifth resistor, a third diode, and a fourth diode. The third resistor has a first terminal and a second terminal, and the first terminal of the third resistor receives one of the detection signals. The second capacitor has a first terminal and a second terminal, the first terminal of the second capacitor is coupled to the second terminal of the third resistor, and the second terminal of the second capacitor is coupled to the ground terminal. The fourth resistor has a first terminal and a second terminal, and the first terminal of the fourth resistor receives a first reference signal. The comparing unit has a first input terminal, a second input terminal and an output terminal, the first input terminal of the comparing unit is coupled to the second terminal of the third resistor, and the second input terminal of the comparing unit is coupled to the second terminal of the fifth resistor. The fifth resistor has a first terminal and a second terminal, and the first terminal of the fifth resistor is coupled to the output terminal of the comparison unit.

The third diode has a first terminal and a second terminal, the anode terminal of the third diode is coupled to the second terminal of the fifth resistor, and the cathode terminal of the third diode is coupled to the first input terminal of the comparison unit. The fourth diode has a first end and a second end, the anode of the fourth diode is coupled to the output end of the comparison unit, and the cathode end of the fourth diode generates a protection signal.

In an embodiment, the aforementioned protection unit further includes a reference voltage generator. The reference voltage generator is coupled to the first end of the fifth resistor for receiving the second reference signal to generate the first reference signal.

In an embodiment, the aforementioned reference voltage generator includes a sixth resistor, a third capacitor, a Zener diode, a seventh resistor, an eighth resistor, and a fourth capacitor. The sixth resistor has a first terminal and a second terminal, and the first terminal of the sixth resistor receives the second reference signal. The third capacitor has a first terminal and a second terminal, the first terminal of the third capacitor is coupled to the second terminal of the sixth resistor, and the second terminal of the third capacitor is coupled to the ground terminal. The Zener diode has an anode end and a cathode end, the cathode end of the Zener diode is coupled to the first end of the third capacitor, and the second end of the Zener diode is coupled to the second end of the third capacitor. The seventh resistor has a first terminal and a second terminal, the first terminal of the seventh resistor is coupled to the cathode terminal of the Zener diode, and the second terminal of the seventh resistor generates a first reference signal. The eighth resistor has a first terminal and a second terminal, the first terminal of the eighth resistor is coupled to the first terminal of the seventh resistor, and the second terminal of the eighth resistor is coupled to the cathode terminal of the Zener diode. The fourth capacitor has a first terminal and a second terminal, the first terminal of the fourth capacitor is coupled to the first terminal of the eighth resistor, and the second terminal of the fourth capacitor is coupled to the second terminal of the eighth resistor.

In an embodiment, the aforementioned control unit includes a ninth resistor, a second switch unit, an optocoupler, and a pulse width modulation unit. The ninth resistor has a first end and a second end, the first end of the ninth resistor receives the protection signal, and the second end of the ninth resistor is coupled to the ground. The second switch unit has a first terminal, a second terminal and a third terminal, the first terminal of the second switch unit is coupled to the first terminal of the ninth resistor, and the second terminal of the second switch unit is coupled to the ground terminal. The optocoupler is coupled to the third terminal of the second switch unit, and is used for generating a coupling signal according to whether the second switch unit is turned on or not. The pulse width modulation unit is coupled to the optocoupler for receiving the coupled signal to generate a control signal.

In an embodiment, the LED driving device further includes a filtering unit and a rectifying unit. The filter unit receives a power supply voltage and filters the power supply voltage to generate a filter voltage. The rectifying unit is coupled to the filtering unit to receive the filtered voltage and rectify the filtered voltage to generate a working voltage.

The light-emitting diode driving device disclosed in the present invention, the light-emitting diode driving device, uses the detection of the current flowing through the light-emitting diode unit to generate a detection signal, and then generates a protection signal according to the detection signal to adjust the voltage level of the control signal. Further, it is controlled whether the voltage conversion unit generates an output voltage. In this way, the protection functions of Over Current Protection (OCP), Over Voltage Protection (OVP) and power misconnection can be effectively achieved.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 is the schematic diagram of light-emitting diode driving circuit of the present invention;

FIG. 2 is a detailed schematic diagram of the LED driving circuit of the present invention.

Among them, reference signs

100, 200 LED drive device

110 voltage conversion unit

120_1, 120_2 detection unit

130 protection unit

140 control unit

180_1, 180_2 LED unit

210 filter unit

220 rectifier unit

222 transformer

224 The first switch unit

226_1, 226_2 protection circuit

228 comparison unit

230 reference voltage generator

232 Second switch unit

234 optocoupler

236 pulse width modulation unit

C1 first capacitor

C2 Second capacitor

C3 third capacitor

C4 fourth capacitor

D1 first diode

D2 second diode

D3 third diode

D4 fourth diode

DZ Zener diode

R1 the first resistor

R2 Second resistor

R3 the third resistor

R4 the fourth resistor

R5 fifth resistor

R6 the sixth resistor

R7 the seventh resistor

R8 Eighth resistor

R9 Ninth resistor

CS control signal

VD_1, VD_2 detection signal

VP protection signal

VREF1 first reference signal

VREF2 Second reference signal

VIN working voltage

VO output voltage

VS supply voltage

GND ground terminal

Detailed ways

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

In the various embodiments listed below, the same or similar elements will be represented by the same reference numerals.

Please refer to FIG. 1 , which are schematic diagrams of the LED driving device of the present invention. The LED driving device 100 of this embodiment is suitable for driving a plurality of LED units 180_1 and 180_2 , wherein the LED units 180_1 and 180_2 are connected in parallel. In one embodiment, each of the LED units 180_1 and 180_2 includes a LED, the anode of the LED serves as the anode of the LED units 180_1 and 180_2 , and the cathode of the LED serves as the cathode of the LED units 180_1 and 180_2 . extreme.

In another embodiment, each of the LED units 180_1 and 180_2 includes a plurality of LEDs, and these LEDs are connected in series to form an LED string. The anode terminal and the cathode terminal of the LED string serve as the cathode terminals of the LED units 180_1 and 180_2 .

The LED driving device 100 includes a voltage conversion unit 110 , detection units 120_1 , 120_2 , a protection unit 130 and a control unit 140 . Wherein, the number of detection units corresponds to the number of light emitting diode units. That is to say, the number of light emitting diode units is 2, the number of detection units is also 2, and the rest can be deduced by analogy.

The voltage conversion unit 110 receives the operating voltage VIN, converts the operating voltage VIN into an output voltage VO according to the control signal CS, and outputs the aforementioned output voltage VO to the anode terminals of the LED units 180_1 and 180_2 . In this embodiment, the working voltage VIN can be provided by, for example, an input power circuit, such as an input power circuit of an AC power supply or a DC power supply.

The detection units 120_1 , 120_2 are respectively coupled to the cathode terminals of the LED units 180_1 , 180_2 for generating detection signals VD_1 , VD_2 . The protection unit 130 is coupled to the detection units 120_1 , 120_2 for receiving the detection signals VD_1 , VD_2 and correspondingly generating the protection signal VP. The control unit 140 is coupled to the protection unit 130 and the voltage conversion unit 110 for receiving the protection signal VP and generating the control signal CS accordingly.

When the LED driving device 100 starts to operate, the voltage conversion unit 110 converts the working voltage VIN into the output voltage VO according to the voltage potential of the control signal CS, and outputs the output voltage VO to the LED units 180_1 and 180_2 , to drive the LED units 1801 and 180_0.

For example, when the voltage level of the control signal CS is a high voltage level, the voltage converting unit 110 will not convert the operating voltage VIN, that is, the voltage converting unit 110 will perform the energy storage operation. When the piezoelectric potential of the control signal CS is a low voltage level, the voltage conversion unit 110 converts the working voltage VIN into the output voltage VO, that is, the voltage conversion unit 110 converts the stored energy voltage into the output voltage VO and outputs it.

Next, the detection units 120_1 and 120_2 detect the current flowing through the LED units 180_1 and 180_2 , and convert the aforementioned current into detection signals VD_1 and VD_2 . After that, the protection unit 130 receives the aforementioned detection signals VD_1 and VD_2 , and generates a corresponding protection signal VP according to the voltage levels of the detection signals VD_1 and VD_2 .

For example, when the voltage level of one of the detection signals VD_1 and VD_2 is higher than a preset value or the voltage level of the detection signals VD_1 and VD_2 is higher than the aforementioned preset value at the same time, the protection unit 130 will correspondingly generate, for example, a high voltage. Potential protection signal VP. When the voltage levels of the detection signals VD_1 and VD_2 are not higher than the aforementioned preset value at the same time, the protection unit 130 will correspondingly generate, for example, a protection signal VP with a low voltage level.

Next, the control unit 140 receives the aforementioned protection signal VP, and generates the control signal CS according to the voltage level of the protection signal VP, that is, adjusts the voltage level of the control signal CS to control whether the voltage conversion unit 110 converts the working voltage VIN. into the output voltage VO.

For example, when the voltage level of the protection signal VP is, for example, a high voltage level, the control unit 140 eg generates a control signal CS with a low voltage level so that the voltage conversion unit 110 does not convert the operating voltage VIN into the output voltage VO. When the voltage level of the protection signal VP is, for example, a low voltage level, the control unit 140, for example, generates a control signal CS with a high voltage level, so that the voltage converting unit 110 converts the operating voltage VIN into an output voltage VO, and outputs the output voltage to the LED unit 180_1 and 180_2 to drive the LED units 180_1 and 180_2.

In this way, the detection signals VD_1 and VD_2 are used to generate the protection signal VP to adjust the voltage potential of the control signal CS, and then control the basis for the voltage conversion unit 110 to generate the output voltage, so as to achieve overvoltage, overcurrent and drive power Misconnection protection.

In this embodiment, the light-emitting diode driving device 100 is used to drive two light-emitting diode units as an example, but the present invention is not limited thereto, and three or more light-emitting diode units can also be driven, and the driving method can refer to the aforementioned implementation example, so it will not be repeated here.

Please refer to FIG. 2 , which is a detailed schematic diagram of the LED driving device of the present invention. The LED driving device 200 of this embodiment is suitable for driving the LED units 180_1 and 180_2 , wherein the LED units 180_1 and 180_2 are connected in parallel. The LED driving device 200 includes a filter unit 210 , a rectification unit 220 , a voltage conversion unit 110 , detection units 120_1 , 120_2 , a protection unit 130 and a control unit 140 .

The filtering unit 210 receives a power supply voltage VS and filters the power supply voltage VS to generate a filtered voltage, wherein the power supply voltage VS is, for example, an AC voltage. The rectifying unit 220 is coupled to the filtering unit 210, receives the filtered voltage, and rectifies the filtered voltage to generate the working voltage VIN.

The voltage conversion unit 110 includes a first resistor R1 , a first capacitor C1 , a transformer 222 , a first diode D1 , a first switch unit 224 and a second diode D2 . The first resistor R1 has a first terminal and a second terminal, and the first terminal of the first resistor R1 receives the working voltage VIN. The first capacitor C1 has a first terminal and a second terminal, the first terminal of the first capacitor C1 is coupled to the first terminal of the first resistor R1, and the second terminal of the first capacitor C1 is coupled to the second terminal of the first resistor R1 .

The transformer 222 has a primary side and a secondary side. The first terminal of the primary side of the transformer 222 is coupled to the first terminal of the first resistor R1, and the second terminal of the secondary side of the transformer 222 is coupled to the ground terminal GND. The cathode terminal of the first diode D1 is coupled to the second terminal of the first resistor R1 , and the anode terminal of the first diode D1 is coupled to the second terminal of the primary side of the transformer 222 .

The first switch unit 224 has a first terminal, a second terminal and a third terminal, the first terminal of the first switch unit 224 is coupled to the anode terminal of the first diode D1, and the second terminal of the first switch unit 224 is coupled to The ground terminal GND, the third terminal of the first switch unit 224 receives the control signal.

In this embodiment, the first switch unit 224 is implemented by, for example, an N-type transistor. The first terminal of the first switch unit 224 is, for example, the drain terminal (Drain) of the N-type transistor, the second terminal of the first switch unit 224 is, for example, the source terminal (Source) of the N-type transistor, and the third terminal of the first switch unit 224 The terminal is, for example, a gate terminal (Gate) of an N-type transistor. However, the present invention is not limited thereto, and the first switch unit 224 can also be implemented by a P-type transistor or other switch elements. The anode terminal of the second diode D2 is coupled to the first terminal of the secondary side of the transformer 222 , and the cathode terminal of the second diode D2 generates an output voltage.

Each of the detection units 120_1 and 120_2 includes a second resistor R2. The second resistor has a first terminal and a second terminal. The first terminal of the second resistor R2 is coupled to the cathode terminals of the corresponding LED units 180_1 and 180_2 to generate detection signals VD_1 and VD_2. The second terminal of the second resistor R2 terminal is coupled to the ground terminal GND.

The protection unit 130 includes a plurality of protection circuits 226_1 and 226_2. The protection circuits 226_1 and 226_2 are respectively one-to-one coupled to the detection units 120_1 and 120_2 for receiving the corresponding detection signals VD_1 and VD_2 and correspondingly generating the protection signal VP. Wherein, the number of protection circuits corresponds to the number of detection units, that is, the number of detection units is 2, the number of protection circuits is also 2, and the rest are analogous.

Moreover, the protection circuits each include a third resistor R3 , a second capacitor C2 , a fourth resistor R4 , a comparison unit 228 , a fifth resistor R6 , a third diode D3 , and a fourth diode D4 , each of 226_1 and 226_2 .

The third resistor R3 has a first terminal and a second terminal, and the first terminal of the third resistor R3 receives one of the detection signals. For example, the first end of the third resistor R3 of the protection circuit 226_1 receives the detection signal VD_1 , and the first end of the third resistor R3 of the protection circuit 226_1 receives the detection signal VD_2 . The second capacitor C2 has a first terminal and a second terminal, the first terminal of the second capacitor C2 is coupled to the second terminal of the third resistor R3, and the second terminal of the second capacitor C2 is coupled to the ground terminal GND.

The fourth resistor R4 has a first terminal and a second terminal, and the first terminal of the fourth resistor R4 receives the first reference signal VREF1 . The comparison unit 228 has a first input terminal (such as a positive input terminal), a second input terminal (such as a negative input terminal) and an output terminal. The first input terminal of the comparison unit 228 is coupled to the second terminal of the third resistor R3. The comparison unit The second input end of 228 is coupled to the second end of the fourth resistor R4.

The fifth resistor R5 has a first terminal and a second terminal, and the first terminal of the fifth resistor R5 is coupled to the output terminal of the comparing unit 228 . The third diode D3 has an anode end and a cathode end, the anode end of the third diode D3 is coupled to the second end of the fifth resistor R5, and the cathode end of the third diode D3 is coupled to the first end of the comparison unit 228 input. The fourth diode D4 has an anode terminal and a cathode terminal, the anode of the fourth diode D4 is coupled to the output terminal of the comparison unit 228 , and the cathode terminal of the fourth diode D4 generates the protection signal VP.

The protection unit 130 also includes a reference voltage generator 230 . The reference voltage generator 230 is coupled to the first end of the fourth resistor R4 for receiving the second reference signal VREF2 to generate the first reference signal VREF1 . Moreover, the reference voltage generator 230 includes a sixth resistor R6, a third capacitor C3, a Zener diode DZ, a seventh resistor R7, an eighth resistor R8, and a fourth capacitor C4.

The sixth resistor R6 has a first terminal and a second terminal, and the first terminal of the sixth resistor R6 receives the second reference signal VREF2 . The third capacitor C3 has a first terminal and a second terminal, the first terminal of the third capacitor C3 is coupled to the second terminal of the sixth resistor R6, and the second terminal of the third capacitor C3 is coupled to the ground terminal GND. The Zener diode DZ has an anode end and a cathode end, the cathode end of the Zener diode DZ is coupled to the first end of the third capacitor C3, and the second end of the Zener diode DZ is coupled to the second end of the third capacitor C3.

The seventh resistor R7 has a first terminal and a second terminal, the first terminal of the seventh resistor R7 is coupled to the cathode terminal of the Zener diode DZ, and the second terminal of the seventh resistor R7 generates the first reference signal VREF1 . The eighth resistor R8 has a first terminal and a second terminal, the first terminal of the eighth resistor R8 is coupled to the first terminal of the seventh resistor R7, and the second terminal of the eighth resistor R8 is coupled to the cathode terminal of the Zener diode DZ. The fourth capacitor C4 has a first end and a second end, the first end of the fourth capacitor C4 is coupled to the first end of the eighth resistor R8, and the second end of the fourth capacitor C4 is coupled to the second end of the eighth resistor R8 .

In this embodiment, the reference voltage generator 230 uses the seventh resistor R7 and the eighth resistor R8 to divide the second reference voltage VREF2 to generate the first reference resistor signal VREF1 .

The control unit 140 includes a ninth resistor R9 , a second switch unit 232 , an optocoupler 234 and a pulse width modulation unit 236 . The ninth resistor R9 has a first terminal and a second terminal, the first terminal of the ninth resistor R9 receives the protection signal VP, and the second terminal of the ninth resistor R9 is coupled to the ground terminal GND.

The second switch unit 232 has a first terminal, a second terminal and a third terminal, the first terminal of the second switch unit 232 is coupled to the first terminal of the ninth resistor R9, and the second terminal of the second switch unit 232 is coupled to the ground Terminal GND.

In this embodiment, the second switch unit 232 is implemented by, for example, an N-type transistor. The first terminal of the second switch unit 232 is, for example, the gate terminal of an N-type transistor, the second terminal of the second switch unit 232 is, for example, the source terminal of the N-type transistor, and the third terminal of the second switch unit 232 is, for example, an N-type transistor. the drain terminal. However, the present invention is not limited thereto, and the second switch unit 232 can also be implemented by a P-type transistor or other switch elements.

The optocoupler 234 is coupled to the third terminal of the second switch unit 232 for generating a coupling signal according to whether the second switch unit 232 is turned on or not. The pulse width modulation unit 236 is coupled to the optical coupler 234 for receiving the coupled signal to generate the control signal CS.

When the LED driving device 200 operates and the voltage conversion unit 110 generates the output voltage VO to drive the LED units 180_1 and 180_2, the detection units 120_1 and 120_2 detect the currents flowing through the LED units 180_1 and 180_2 respectively to generate detection signals. VD_1, VD_2. Moreover, the detection signals VD_1 and VD_2 are respectively output to the first input terminals of the comparison unit 228 of the protection circuits 226_1 and 226_2 .

Next, the comparison unit 228 of the protection circuit 226_1 compares the signals received by the first input terminal and the second input terminal, that is, the voltage level of the detection signal VD_1 and the first reference signal VREF1 , and adjusts the voltage level of the protection signal VP accordingly. .

On the other hand, the comparison unit 228 of the protection circuit 226_1 also compares the signals received by the first input terminal and the second input terminal, that is, compares the detection signal VD_2 with the voltage level of the first reference signal VREF1, and adjusts the protection signal accordingly. The voltage potential of VP.

When the currents flowing through the LED units 180_1 and 180_2 are normal, the voltage levels of the detection signals VD_1 and VD_2 will not exceed the voltage level of the first reference voltage VREF1, so the comparison units 228 of the protection circuits 226_1 and 226_2 will output low voltage levels. signal, so that the protection signal VP generated by the protection unit 130 is a low voltage level.

However, when the current flowing through the LED units 180_1 and 180_2 suddenly increases, that is, over-current, over-voltage or wrong power connection occurs, the voltage levels of the detection signals VD_1 and VD_2 will continue to rise. Moreover, the comparison unit 228 of the protection circuits 226_1 and 226_2 will continuously compare the detection signals VD_1 , VD_2 with the first reference signal VREF1 . Next, when the comparison unit 228 of the protection circuits 226_1 and 226_2 compares that the detection signal VD_1, VD_2 has a voltage level higher than the first reference signal VREF1, it will generate a signal with a high voltage level correspondingly, so that the protection signal VP generated by the protection unit 130 for the high voltage potential.

In addition, since the sixth resistor R6 and the third diode D3 are arranged between the first input terminal and the output terminal of the comparison unit 228 of the protection circuits 226_1 and 226_2, and there is positive feedback (Feedback), when the protection circuit When the comparison units 228 of the protection circuits 226_1 and 226_2 output high-voltage signals, the comparison units 228 of the protection circuits 226_1 and 226_2 will lock this state to complete the self-locking function, and then keep outputting high-voltage signals.

Next, when the protection unit 130 generates the protection signal VP with a high voltage level, and the protection signal VP is provided to the second switch unit 232 , so that the second switch unit 232 is turned on. Afterwards, the light emitting end of the optocoupler 234 is turned on and emits light, so that the light receiving end of the optocoupler 234 is turned on and correspondingly outputs a signal of a high voltage level to the pulse width modulation unit 236 . Next, the pulse width modulation unit 236 generates a low voltage control signal CS to the voltage conversion unit 110 according to the high voltage signal generated by the optocoupler 234 , so that the voltage conversion unit 110 stops generating the output voltage VO.

In this way, the protection functions of over-current, over-voltage and wrong connection of power supply can be effectively achieved, so as to avoid damage to the LED units 180_1 and 180_2 .

In the foregoing embodiments, the LED driving devices 100 and 200 take driving a plurality of LED units as an example, but the present invention is not limited thereto. The LED driving devices 100 and 200 may also only drive one LED unit, and the detection unit and The number of the protection circuit is also one (that is, the number corresponding to the number of LED units), and its related driving method can refer to the description of the foregoing embodiments, so it will not be repeated here.

The light-emitting diode driving device of the present invention uses the detection of the current flowing through the light-emitting diode unit to generate a detection signal, and then generates a protection signal according to the detection signal to adjust the voltage potential of the control signal, and then controls whether the voltage conversion unit generates The output voltage. In this way, the protection functions of over-current, over-voltage and wrong connection of power supply can be effectively achieved.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (9)

1. a light emitting diode drive device, is suitable for driving a plurality of light emitting diodes, and wherein those light emitting diodes are connected in parallel, and it is characterized in that, this light emitting diode drive device comprises:

One voltage conversion unit, receives an operating voltage, and according to a control signal, and convert this operating voltage to an output voltage, and export this output voltage to the anode tap of those light emitting diodes;

A plurality of detecting units, couple respectively the cathode terminal of those light emitting diodes, in order to produce a plurality of detection signals;

One protected location, couples those detecting units, and in order to receive those detection signals, and correspondence produces a guard signal according to this; And

One control unit, couples this protected location and this voltage conversion unit, in order to receive this guard signal, and produces according to this this control signal.

2. light emitting diode drive device according to claim 1, is characterized in that, this voltage conversion unit comprises:

One first resistance, has a first end and one second end, and this first end of this first resistance receives this operating voltage;

One first electric capacity, has a first end and one second end, and this first end of this first electric capacity couples this first end of this first resistance, and the second end of this first electric capacity couples this second end of this first resistance;

One transformer, has a primary side and a secondary side, and the first end of this primary side of this transformer couples this first end of this first resistance, and the second end of this secondary side of this transformer couples earth terminal;

One first diode, has an anode tap and a cathode terminal, and this cathode terminal of this first diode couples this second end of this first resistance, and this anode tap of this first diode couples the second end of this primary side of this transformer;

One first switch element, there is a first end, one second end and one the 3rd end, this first end of this first switch element couples this anode tap of this first diode, and this second end of this first switch element couples earth terminal, and the 3rd termination of this first switch element is received this control signal; And

One second diode, has an anode tap and a cathode terminal, and this anode tap of this second diode couples the first end of this secondary side of this transformer, and this cathode terminal of this second diode produces this output voltage.

3. light emitting diode drive device according to claim 1, is characterized in that, those detecting units comprise separately:

One second resistance, has a first end and one second end, and this first end of this second resistance couples the cathode terminal of this corresponding light emitting diode, and to produce this detection signal, this second end of this second resistance couples earth terminal.

4. light emitting diode drive device according to claim 1, is characterized in that, this protected location comprises:

A plurality of protective circuits, couple respectively those detecting units one to one, and in order to receive those corresponding detection signals, and correspondence produces this guard signal according to this.

5. light emitting diode drive device according to claim 4, is characterized in that, those protective circuits comprise separately:

One the 3rd resistance, has a first end and one second end, and this first end of the 3rd resistance receives one of those detection signals;

One second electric capacity, has a first end and one second end, and this first end of this second electric capacity couples this second end of the 3rd resistance, and this second end of this second electric capacity couples earth terminal;

One the 4th resistance, has a first end and one second end, and this first end of the 4th resistance receives one first reference signal;

One comparing unit, has a first input end, one second input and an output, and this first input end of this comparing unit couples this second end of the 3rd resistance, and this of this comparing unit the second input couples this second end of the 4th resistance;

One the 5th resistance, has a first end and one second end, and this first end of the 5th resistance couples this output of this comparing unit;

One the 3rd diode, has an anode tap and a cathode terminal, and this anode tap of the 3rd diode couples this second end of the 5th resistance, and this cathode terminal of the 3rd diode couples this first input end of this comparing unit; And

One the 4th diode, has an anode tap and a cathode terminal, and this anode of the 4th diode couples this output of this comparing unit, and this cathode terminal of the 4th diode produces this guard signal.

6. light emitting diode drive device according to claim 5, is characterized in that, this protected location also comprises:

One reference voltage generator, couples this first ends of those the 5th resistance, in order to receive one second reference signal, to produce this first reference signal.

7. light emitting diode drive device according to claim 6, is characterized in that, this reference voltage generator comprises:

One the 6th resistance, has a first end and one second end, and this first end of the 6th resistance receives this second reference signal;

One the 3rd electric capacity, has a first end and one second end, and this first end of the 3rd electric capacity couples this second end of the 6th resistance, and this second end of the 3rd electric capacity couples earth terminal;

One Zener diode, has an anode tap and a cathode terminal, and this cathode terminal of this Zener diode couples this first end of the 3rd electric capacity, and this of this Zener diode the second end couples this second end of the 3rd electric capacity;

One the 7th resistance, has a first end and one second end, and this first end of the 7th resistance couples this cathode terminal of this Zener diode, and this second end of the 7th resistance produces this first reference signal;

One the 8th resistance, has a first end and one second end, and this first end of the 8th resistance couples this first end of the 7th resistance, and this second end of the 8th resistance couples this cathode terminal of this Zener diode; And

One the 4th electric capacity, has a first end and one second end, and this first end of the 4th electric capacity couples this first end of the 8th resistance, and this second end of the 4th electric capacity couples this second end of the 8th resistance.

8. light emitting diode drive device according to claim 1, is characterized in that, this control unit comprises:

One the 9th resistance, has a first end and one second end, and this first end of the 9th resistance receives this guard signal, and this second end of the 9th resistance couples earth terminal;

One second switch unit, has a first end, one second end and one the 3rd end, and this first end of this second switch unit couples the first end of the 9th resistance, and this second end of this second switch unit couples earth terminal;

In order to the conducting according to this second switch unit whether one optical coupler, couples the 3rd end of this second switch unit,, and produce according to this coupled signal; And

One pulse-width modulation unit, couples this optical coupler, in order to receive this coupled signal, to produce this control signal.

9. light emitting diode drive device according to claim 1, is characterized in that, also comprises:

One filter unit, receives a supply voltage, and this supply voltage is carried out to filtering, to produce a filtering voltage; And

One rectification unit, couples this filter unit, receives this filtering voltage, and this filtering voltage is carried out to rectification, to produce this operating voltage.

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