CN102223743A - Light emitting diode (LED) driving control circuit and method thereof - Google Patents
Light emitting diode (LED) driving control circuit and method thereof Download PDFInfo
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- CN102223743A CN102223743A CN2010101521898A CN201010152189A CN102223743A CN 102223743 A CN102223743 A CN 102223743A CN 2010101521898 A CN2010101521898 A CN 2010101521898A CN 201010152189 A CN201010152189 A CN 201010152189A CN 102223743 A CN102223743 A CN 102223743A
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Abstract
The invention discloses a light emitting diode (LED) driving control circuit and a method thereof. The circuit comprises: a pulse width regulation and control unit, which is used to output an adjustable pulse signal of a switch signal in a LED serial pathway so as to perform light modulation on LEDs in the LED serial pathway; a current limiting protection unit, which is connected with the pulse width regulation and control unit and the LED serial pathway, is used to control conduction of the LED serial pathway through the received pulse signal, and restrict and detect a current value, wherein the current flows through the LED serial pathway. When the current value exceeds a threshold value, the current limiting protection unit sends an over-current control signal to the pulse width regulation and control unit. After receiving the over-current control signal, the pulse width regulation and control unit is also used to send a shutdown signal to the current limiting protection unit so as to turn off the LED serial pathway. Current limiting protection to the LEDs can be achieved.
Description
Technical field
The present invention relates to light-emitting diode (Light Emitting Diode is called for short LED) Driving technique, relate in particular to a kind of light-emitting diode Drive and Control Circuit and method.
Background technology
In LCD TV, the LED TV has replaced traditional CCFL LCD TV, becomes the main flow of panel TV.One of core component in the LED TV is exactly the LED-backlit source, and LED-backlit source active illuminating through the TFT-LCD panel, forms image.LED-backlit is divided into straight-down negative and two kinds of side-light types are backlight, and the direct-light-type backlight color consistency is good, for power supply control flexibly; Side-light type back light, cost is low, and the relative direct-light-type backlight of thickness significantly reduces.In the LED-backlit source technology, no matter be for which kind of backlight technology, one of the core component in LED-backlit source is the LED Drive and Control Circuit.By of the accurate control of LED Drive and Control Circuit to LED, can improve the operating efficiency in LED-backlit source greatly, reach good display effect.
But, in the LED Drive and Control Circuit of existing drive controlling LED, because the design of its internal structure, cause the voltage of LED of its input serial connection limited, input voltage is tens volts scope, thereby restricted for the series connection quantity of LED; Simultaneously, perfect inadequately to the detection limit function of the electric current by LED, electric current generally is limited in tens milliamperes scope, the damage in the time of also can causing LED overcurrent under the unusual condition; And control complexity, the precision of pulse-width modulation (PWM) signal of LED being carried out light modulation is low, thereby the driving efficient of LED Drive and Control Circuit is low.
Summary of the invention
The invention provides a kind of light-emitting diode Drive and Control Circuit and method, improving the driving efficient of light-emitting diode Drive and Control Circuit, and the light-emitting diode of its drive controlling is carried out current-limiting protection.
The invention provides a kind of light-emitting diode Drive and Control Circuit, comprising:
Pulsewidth regulation and control unit, be used to export adjustable as the work pulse signal of switching signal on road of light emitting diode string, carry out light modulation with the light-emitting diode on the road that described light emitting diode string is worked, wherein, importing the work magnitude of voltage of voltage signal on road of described light emitting diode string determines according to the work number of the light-emitting diode that connects on the road of described light emitting diode string;
The current-limiting protection unit, be connected with described pulsewidth regulation and control unit and the described light emitting diode string road of working, be used for controlling the work conducting on road of described light emitting diode string by the described pulse signal that receives, restriction flow through described light emitting diode string work the road electric current size and the work size of electric current on road of the described light emitting diode string of flowing through detected, work after the electric current on road exceeds threshold value in the described described light emitting diode string of flowing through, sent flow control signals to described pulsewidth regulation and control unit;
Described pulsewidth regulation and control unit also be used for receive described cross flow control signals after, send shutdown signal to described current-limiting protection unit, to turn-off the described light emitting diode string road of working.
The present invention also provides a kind of light-emitting diode drive controlling method, comprising:
The output of pulsewidth regulation and control unit is adjustable as the work pulse signal of switching signal on road of light emitting diode string, wherein, importing the work magnitude of voltage of voltage signal on road of described light emitting diode string determines according to the work number of the light-emitting diode that connects on the road of described light emitting diode string;
After the current-limiting protection unit receives the described pulse signal of described pulsewidth regulation and control unit output, control the work conducting on road of described light emitting diode string and carry out light modulation with the light-emitting diode on road that described light emitting diode string is worked;
Described current-limiting protection unit restriction flow through described light emitting diode string work the road electric current size and the work size of electric current on road of the described light emitting diode string of flowing through detected, work after the electric current on road exceeds threshold value in the described described light emitting diode string of flowing through, sent flow control signals to described pulsewidth regulation and control unit;
Described pulsewidth regulation and control unit receive described cross flow control signals after, send shutdown signal to described current-limiting protection unit, to turn-off the described light emitting diode string road of working.
Light-emitting diode Drive and Control Circuit provided by the invention and method, the adjustable pulse signal of pulsewidth regulation and control unit output is as the pulse signal of dimming light-emitting diode, and adopt one road independent voltage signal to provide supply power voltage, thereby can select suitable supply power voltage according to the work number of the light-emitting diode that is connected in series in the road of light emitting diode string for light-emitting diode; Simultaneously, increased, the work electric current on road of light emitting diode string has been carried out current limliting, and can avoid the work damage of the electric current on road light-emitting diode when exceeding threshold value of light emitting diode string the work current-limiting protection unit of electric current on road of light emitting diode string.This light-emitting diode Drive and Control Circuit and method are simple, easy to use.
Description of drawings
The structural representation of the LED Drive and Control Circuit that Fig. 1 provides for the embodiment of the invention one;
The structural representation of the LED Drive and Control Circuit that Fig. 2 provides for the embodiment of the invention two;
The structural representation of the LED Drive and Control Circuit that Fig. 3 provides for the embodiment of the invention three;
The structural representation of the analog pulse width regulation and control unit of the LED Drive and Control Circuit that Fig. 4 provides for the embodiment of the invention three;
The selected cell of the LED Drive and Control Circuit that Fig. 5 provides for the embodiment of the invention three and the structural representation of switch element;
The schematic flow sheet of the LED drive controlling method that Fig. 6 provides for the embodiment of the invention four;
The schematic flow sheet of the LED drive controlling method that Fig. 7 provides for the embodiment of the invention five.
Reference numeral:
100-pulsewidth regulation and control unit; 101-digital pulse width regulation and control unit;
102-analog pulse width regulation and control unit; 200-current-limiting protection unit;
The 201-LED control sub unit; 202-current limliting subelement;
203-overcurrent protection subelement; The 300-LED IEEE Std serial highway;
The 500-selected cell; The 600-switch element.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
The structural representation of the LED Drive and Control Circuit that Fig. 1 provides for the embodiment of the invention one, as shown in Figure 1, this LED Drive and Control Circuit comprises: pulsewidth regulation and control unit 100 and current-limiting protection unit 200.Pulsewidth regulation and control unit 100 is used to export the pulse signal of adjustable switching signal as LED IEEE Std serial highway 300, so that the LED on the LED IEEE Std serial highway 300 is carried out light modulation, wherein, the voltage signal V of input LED IEEE Std serial highway 300
InMagnitude of voltage determine according to the number of the LED that connects on the LED IEEE Std serial highway 300.Current-limiting protection unit 200 is connected with LED IEEE Std serial highway 300 with pulsewidth regulation and control unit 100; be used for conducting by the pulse signal control LED IEEE Std serial highway 300 that receives; restriction flow through LED IEEE Std serial highway 300 electric current size and the size of the electric current of the LED IEEE Std serial highway 300 of flowing through detected; after the electric current of the LED IEEE Std serial highway 300 of flowing through exceeds threshold value, sent flow control signals to pulsewidth regulation and control unit 100.Pulsewidth regulation and control unit 100 also is used for after receiving flow control signals, sends shutdown signal to current-limiting protection unit 200, to turn-off LED IEEE Std serial highway 300.
The LED Drive and Control Circuit that present embodiment provides, the adjustable pulse signal of pulsewidth regulation and control unit output is as the pulse signal of LED light modulation, and adopt one road independent voltage signal to provide supply power voltage, thereby can select suitable supply power voltage according to the number of the LED that is connected in series in the LED IEEE Std serial highway for LED; Simultaneously; increased current-limiting protection unit, the electric current of LED IEEE Std serial highway has been carried out current limliting the electric current of LED IEEE Std serial highway, and can exceed threshold value at the electric current of LED IEEE Std serial highway the time; in time feed back shutdown signal, thereby avoid the damage of the LED on the LED IEEE Std serial highway to the LED IEEE Std serial highway.This LED Drive and Control Circuit is simple, easy to use, can be applied in direct-light-type backlight driving and the side-light type back light driving.
The structural representation of the LED Drive and Control Circuit that Fig. 2 provides for the embodiment of the invention two; as shown in Figure 2; pulsewidth regulation and control unit 100 and current-limiting protection unit 200 in the LED Drive and Control Circuit that provides as above-mentioned embodiment one is provided this LED Drive and Control Circuit; same section specifically describes as above, repeats no more.Describe the concrete structure of current-limiting protection unit 200 below in detail.This current-limiting protection unit 200 comprises: LED control sub unit 201, current limliting subelement 202 and overcurrent protection subelement 203; wherein LED control sub unit 201 is connected with pulsewidth regulation and control unit 100 with overcurrent protection subelement 203, and current limliting subelement 202 is connected with LED control sub unit 201 by overcurrent protection subelement 203.When pulse signal was high level, LED control sub unit 201 conducting LED IEEE Std serial highways 300 were with voltage signal V
InInput LED IEEE Std serial highway 300 is each LED power supply on the LED IEEE Std serial highway 300.By changing the normal voltage signal V of input current limliting subelement 202
RefMagnitude of voltage or normalized current signal I
sCurrent value change the current value of the predetermined current signal that exports LED IEEE Std serial highway 300 to.Overcurrent protection subelement 203 receives the predetermined current signal of current limliting subelement 202 outputs, and exports LED IEEE Std serial highway 300 to; The current value of the predetermined current signal that current limliting subelement 202 can also be exported and the current value of the actual current on the LED IEEE Std serial highway 300 of flowing through compare, if the current value of the current value overgauge current signal of actual current then sent flow control signals to pulsewidth regulation and control unit 100.
As shown in Figure 2, LED control sub unit 201 specifically can comprise: the first switch element Q1, first resistance R 1 and the first voltage-stabiliser tube D1, wherein the first switch element Q1 can be triode or field effect transistor, can be field effect transistor in the present embodiment.The first input end of the first switch element Q1 (as the grid of field effect transistor) connects the output of pulsewidth regulation and control unit 100, be used for the received pulse signal, second input of the first switch element Q1 (as the source electrode of field effect transistor) connects an end of first resistance R 1, the other end input voltage signal V of first resistance R 1
In, the output of LED IEEE Std serial highway 300, the first switch element Q1 that one group of LED of the output of the first switch element Q1 (as the drain electrode of field effect transistor) serial connection forms also connects the end of the first voltage-stabiliser tube D1, the other end ground connection of the first voltage-stabiliser tube D1.
As shown in Figure 2, current limliting subelement 202 specifically can comprise: current limliting input a, the second voltage-stabiliser tube D2, the 3rd resistance R 3, the 4th resistance R 4, the first operational amplifier F1 and second switch element Q2.Current limliting input a connects the positive input of the first operational amplifier F1 and imports normal voltage signal V
RefOr normalized current signal I
sThe end of the second voltage-stabiliser tube D2 connects current limliting input a, the other end ground connection of the second voltage-stabiliser tube D2; One end of the 3rd resistance R 4 connects the negative input of the first operational amplifier F1, and an end of the 4th resistance R 3 connects current limliting input a, and the other end of the other end of the 3rd resistance R 3 and the 4th resistance R 4 is ground connection respectively; The output of the first operational amplifier F1 connects the input (as the grid of field effect transistor) of second switch element Q2, first output of second switch element Q2 (as the drain electrode of field effect transistor) connects the negative input of the first operational amplifier F1, second output of second switch element Q2 (as the source electrode of field effect transistor) output predetermined current signal.
As shown in Figure 2, overcurrent protection subelement 203 specifically can comprise: second resistance R 2, the 5th resistance R 5 and the second operational amplifier F2.One end of second resistance R 2 connects the positive input of the second operational amplifier F2 and receives the predetermined current signal, and the other end of second resistance R 2 connects the other end of first resistance R 1; One end of the 5th resistance R 5 connects the negative input of the second operational amplifier F2, and the other end of the 5th resistance R 5 connects an end of first resistance R 1; The output of the second operational amplifier F2 sent flow control signals to pulsewidth regulation and control unit 100.
Particularly, current limliting subelement 202 can provide the predetermined current signal for LED IEEE Std serial highway 300 by following two kinds of mode of operations, and this predetermined current signal is the flow through electric current of LED IEEE Std serial highway 300 of expectation.
First kind of pattern is for using normal voltage signal V
Ref, wherein, V
RefBe adjustable flexibly, need external.The flow through current value of R2 and R1
When Q1 opened, the electric current that adds on the LED was predetermined current signal I
Ref, at this moment, the voltage on the R2 is
Virtual voltage on the R1 is V1=V
In-N * V
Ledon, wherein, V
LedonIt is the operating voltage of LED.If hypothesis R1=R2 so, when V1＞V2, illustrate that the actual current that passes through LED IEEE Std serial highway 300 is greater than I
RefWill make one of second operational amplifier F2 generation cross flow control signals and be sent to pulsewidth regulation and control unit 100; thereby make pulsewidth regulation and control unit 100 send shutdown signal,, LED IEEE Std serial highway 300 is protected to turn-off the first switch element Q1 to LED control sub unit 201.Because V
RefAdjustability, LED IEEE Std serial highway 300 is worked in very big current range, and can obtain current-limiting protection timely.
Second kind of pattern is for using constant-current source I
s, wherein, I
sBe adjustable flexibly.The flow through current value of R2 and R1
When Q1 opened, the electric current that adds on the LED was predetermined current signal I
Ref, at this moment, the voltage on the R2 is
Voltage on the R1 is V1=V
In-N * V
Ledon, wherein, V
LedonIt is the operating voltage of LED.If hypothesis R1=R2 so, when V1＞V2, illustrate that the actual current that passes through LED IEEE Std serial highway 300 is greater than I
RefWill make one of operational amplifier F2 generation cross flow control signals and be sent to pulsewidth regulation and control unit 100; thereby make pulsewidth regulation and control unit 100 send shutdown signal,, LED IEEE Std serial highway 300 is protected to turn-off the first switch element Q1 to LED control sub unit 201.Because I
sAdjustability, LED IEEE Std serial highway 300 is worked in very big current range, and can obtain current-limiting protection timely.
The LED Drive and Control Circuit that present embodiment provides by the duty ratio of pulsewidth regulation and control unit regulating impulse signal, is controlled unlatching and the shutoff of the first switch element Q1, again by second switch element Q2, the 3rd resistance R 3, the 4th resistance R 4 and normal voltage signal V
Ref/ normalized current signal I
sThe current limliting subelement of forming provides the predetermined current signal for the LED IEEE Std serial highway; also whether change by the actual current of overcurrent protection subelement monitoring in real time by the LED IEEE Std serial highway; if greater than the current value of predetermined current signal; then produced flow control signals; thereby turn-off the first switch element Q1 by pulsewidth regulation and control unit, thereby can protect the unlikely damage of LED on the LED IEEE Std serial highway.Like this, having guaranteed has bigger current range in the LED IEEE Std serial highway that the LED Drive and Control Circuit driven, generally can from several milliamperes to several peaces, and protection LED is not fragile.Simultaneously, for the voltage signal V that imports
InWithout limits, scope can lie prostrate several hectovolts from several, and the quantity of the LED that can connect according to needs in the LED IEEE Std serial highway adopt rational voltage signal V
InMagnitude of voltage, thereby make the driving of LED not be subjected to the restricted number of LED, can enough LED Drive and Control Circuit seldom drive the LED of greater number, saved the cost that drives design.
The structural representation of the LED Drive and Control Circuit that Fig. 3 provides for the embodiment of the invention three; as shown in Figure 3; pulsewidth regulation and control unit 100 and current-limiting protection unit 200 in the LED Drive and Control Circuit that provides as above-mentioned embodiment one and embodiment two is provided this LED Drive and Control Circuit; the specific descriptions of same section as above repeat no more.Wherein, pulsewidth regulation and control unit 100 specifically can comprise: digital pulse width regulation and control unit 101 and/or analog pulse width regulation and control unit 102; Digital pulse width regulation and control unit 101 is used to export the digital pulse signal of adjustable switching signal as LED IEEE Std serial highway 300, so that the LED on the LED IEEE Std serial highway 300 is carried out light modulation, analog pulse width regulation and control unit 102 is used to export the analog pulse signal of adjustable switching signal as LED IEEE Std serial highway 300, so that the LED on the LED IEEE Std serial highway 300 is carried out light modulation.
Wherein, digital pulse width regulation and control unit 101 can adopt micro-control unit to control core as it, this part can be reserved standard interface and give the user, thereby the user can directly write control data and code, and by other sheet choosings the digital pulse width signal of output is controlled.Simultaneously; in the present embodiment, this digital pulse width regulation and control unit 101 also can provide the current-limiting protection function of LED, promptly when receiving the mistake flow control signals that overcurrent protection subelement 203 sends; send shutdown signal to LED control sub unit 201, to turn-off LED IEEE Std serial highway 300.
The structural representation of the analog pulse width regulation and control unit of the LED Drive and Control Circuit that Fig. 4 provides for the embodiment of the invention three, as shown in Figure 4, analog pulse width regulation and control unit 102 specifically can comprise: variable resistor R, the 6th resistance R 6, the 7th resistance R 7, the 8th resistance R 8, the 9th resistance R 9, capacitor C, the 3rd operational amplifier F3, the first diode D3, the second diode D4 and the 3rd voltage-stabiliser tube D5.The end of variable resistor R connects the positive pole of the first diode D3, and the other end of variable resistor R connects the negative pole of the second diode D4; The positive pole of the negative pole of the first diode D3 and the second diode D4 is connected an end of the 9th resistance R 9, and the other end of the 9th resistance R 9 connects an end of capacitor C, the other end ground connection of capacitor C; The negative input of the 3rd operational amplifier F3 connects an end of capacitor C, and the positive input of the 3rd operational amplifier F3 connects an end of the 6th resistance R 6 and an end of the 7th resistance R 7, and the output of the 3rd operational amplifier F3 connects an end of the 8th resistance R 8; The other end ground connection of the 6th resistance R 6, the other end of the 7th resistance R 7 are connected the convertible tip of variable resistor R with the other end of the 8th resistance R 8, and output analog pulse signal Ua; The end of the 3rd voltage-stabiliser tube D5 connects the other end of the 7th resistance R 7, and the other end of the 3rd voltage-stabiliser tube D5 connects the other end of the 6th resistance R 6.Wherein, regulate, capacitor C is carried out the adjusting of charge/discharge, to change the duty ratio of the analog pulse signal of exporting by resistance to variable resistor R.
Particularly, as shown in Figure 4, analog pulse signal Ua is timing when output, the first diode D3 conducting, and the second diode D4 ends, and the charge constant of capacitor C is: the τ 1=(C of R ' w+rd1+R9); When output analog pulse signal Ua when negative, the first diode D3 ends, the second diode D4 conducting, the charge constant of capacitor C is: the τ 2=(C of Rw-R ' w+rd2+R9).Wherein, Rw is the resistance of the moved end of variable resistor R to upper extreme point, and R ' w is the resistance of the moved end of variable resistor R to lower extreme point, the equivalent resistance the when equivalent resistance when rd1 is the first diode D3 conducting, rd2 are the second diode D4 conducting.The internal resistance of the backward resistance of D1, D2 and the 3rd voltage-stabiliser tube D5 can be ignored.
With the method for estimation can obtain capacitor C charging time T 1 and cycle of oscillation time T be respectively:
Calculate and can get through arrangement:
As seen, regulating variable resistor R can make the duty ratio of the waveform of output analog pulse signal Ua change.
This LED Drive and Control Circuit can also comprise: selected cell 500 and switch element 600.The selected cell of the LED Drive and Control Circuit that Fig. 5 provides for the embodiment of the invention three and the structural representation of switch element as shown in Figure 5, are an example of selected cell 500 and switch element 600.Wherein, selected cell 500 is connected between pulsewidth regulation and control unit 100 and the current-limiting protection unit 200; be connected with analog pulse width regulation and control unit 102 with the digital pulse width regulation and control unit 101 that comprises in the pulsewidth regulation and control unit 100, receive and select output digital pulse signal or analog pulse signal.Switch element 600 is connected between selected cell 500 and the current-limiting protection unit 200, is used for selecting the digital pulse signal or the analog pulse signal of output to amplify to selected cell 500.
Particularly, as shown in Figure 5, analog pulse signal Ua is the output of analog pulse width regulation and control unit 102 controls, digital pulse signal Ub is the output of digital pulse width regulation and control unit 101 controls, the Gp signal is the shutdown signal that the microprocessing unit of digital pulse width regulation and control unit 101 provides, the SEL signal is an outer signal, can be set by user oneself, gives over to standby.Can set, when the actual current by LED IEEE Std serial highway 300 exceeded the threshold value warning, the Gp signal was " 0 ", otherwise does not exceed threshold value by the actual current of LED IEEE Std serial highway 300, and the Gp signal is " 1 ".So, the output of selected cell 500 can be expressed as PGATE=Ua * SEL+Ub * SEL+Gp.In order to reach the unlatching threshold value of the first switch element Q1, this PGATE can also be through the amplification of switch element 600, and output GATE signal is linked into current-limiting protection unit 200 and provides required signal for it.
The LED Drive and Control Circuit that present embodiment provides, digital pulse width regulation and control unit and analog pulse width regulation and control unit have been adopted, wherein, analog pulse width regulation and control unit implementation structure is simple, the unit is accurate but control precision does not have the digital pulse width regulation and control, therefore, has adopted two kinds of pulsewidth regulation and control unit to combine among the present invention, select for the user, thereby improve the operating efficiency of LED Drive and Control Circuit greatly.In addition, increased current-limiting protection unit, the electric current of LED IEEE Std serial highway has been carried out current limliting the electric current of LED IEEE Std serial highway, and can exceed threshold value at the electric current of LED IEEE Std serial highway the time, in time feed back shutdown signal, thereby avoid the damage of the LED on the LED IEEE Std serial highway to the LED IEEE Std serial highway; For the voltage signal of importing without limits, scope can lie prostrate several hectovolts from several, can be according to the quantity of the LED of needs connection in the LED IEEE Std serial highway, adopt the magnitude of voltage of rational voltage signal, thereby the driving that makes LED is not subjected to the restricted number of LED, the LED that the enough LED Drive and Control Circuit seldom of energy drive greater number has saved the cost that drives design.
The schematic flow sheet of the LED drive controlling method that Fig. 6 provides for the embodiment of the invention four as shown in Figure 6, comprises the steps:
The restriction of step 603, described current-limiting protection unit flow through described LED IEEE Std serial highway electric current size and the size of the electric current of the described LED IEEE Std serial highway of flowing through detected, after described electric current of flowing through described LED IEEE Std serial highway exceeds threshold value, sent flow control signals to described pulsewidth regulation and control unit;
The LED Drive and Control Circuit that the LED drive controlling method of present embodiment can adopt the embodiment of the invention to provide is carried out, and finishes corresponding flow process, does not repeat them here.
The LED drive controlling method that present embodiment provides, the adjustable pulse signal of pulsewidth regulation and control unit output is as the pulse signal of LED light modulation, and adopt one road independent voltage signal to provide supply power voltage, thereby can select suitable supply power voltage according to the number of the LED that is connected in series in the LED IEEE Std serial highway for LED; Simultaneously; increased current-limiting protection unit, the electric current of LED IEEE Std serial highway has been carried out current limliting the electric current of LED IEEE Std serial highway, and can exceed threshold value at the electric current of LED IEEE Std serial highway the time; in time feed back shutdown signal, thereby avoid the damage of the LED on the LED IEEE Std serial highway to the LED IEEE Std serial highway.This LED Drive and Control Circuit is simple, easy to use.
The schematic flow sheet of the LED drive controlling method that Fig. 7 provides for the embodiment of the invention five as shown in Figure 7, comprises the steps:
The magnitude of voltage of the input voltage of wherein said LED IEEE Std serial highway is determined according to the number of the LED that connects on the described LED IEEE Std serial highway.
The duty ratio of wherein said analog pulse signal can come the charge/discharge of control capacittance to change by regulating variable-resistance resistance.
After step 704, current-limiting protection unit receive described digital pulse signal or described analog pulse signal, select the described digital pulse signal or the described analog pulse signal of output to amplify to described selected cell.
The conducting that step 705, current-limiting protection unit are controlled described LED IEEE Std serial highway according to described digital pulse signal or described analog pulse signal is carried out light modulation with the LED to described LED IEEE Std serial highway.
The restriction of step 706, described current-limiting protection unit flow through described LED IEEE Std serial highway electric current size and the size of the electric current of the described LED IEEE Std serial highway of flowing through detected; after described electric current of flowing through described LED IEEE Std serial highway exceeds threshold value, sent flow control signals to described digital pulse width regulation and control unit.
The LED Drive and Control Circuit that the LED drive controlling method of present embodiment can adopt the embodiment of the invention to provide is carried out, and finishes corresponding flow process, does not repeat them here.
The LED drive controlling method that present embodiment provides, digital pulse width regulation and control unit and analog pulse width regulation and control unit have been adopted, wherein, analog pulse width regulation and control unit implementation structure is simple, the unit is accurate but control precision does not have the digital pulse width regulation and control, therefore, has adopted two kinds of pulsewidth regulation and control unit to combine among the present invention, select for the user, thereby improve the operating efficiency of LED Drive and Control Circuit greatly.In addition, increased current-limiting protection unit, the electric current of LED IEEE Std serial highway has been carried out current limliting the electric current of LED IEEE Std serial highway, and can exceed threshold value at the electric current of LED IEEE Std serial highway the time, in time feed back shutdown signal, thereby avoid the damage of the LED on the LED IEEE Std serial highway to the LED IEEE Std serial highway; For the voltage signal of importing without limits, scope can lie prostrate several hectovolts from several, can be according to the quantity of the LED of needs connection in the LED IEEE Std serial highway, adopt the magnitude of voltage of rational voltage signal, thereby the driving that makes LED is not subjected to the restricted number of LED, the LED that the enough LED Drive and Control Circuit seldom of energy drive greater number has saved the cost that drives design.
It should be noted that at last: above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the spirit and scope of various embodiments of the present invention technical scheme.
Claims (12)
1. a light-emitting diode Drive and Control Circuit is characterized in that, comprising:
Pulsewidth regulation and control unit, be used to export adjustable as the work pulse signal of switching signal on road of light emitting diode string, carry out light modulation with the light-emitting diode on the road that described light emitting diode string is worked, wherein, importing the work magnitude of voltage of voltage signal on road of described light emitting diode string determines according to the work number of the light-emitting diode that connects on the road of described light emitting diode string;
The current-limiting protection unit, be connected with described pulsewidth regulation and control unit and the described light emitting diode string road of working, be used for controlling the work conducting on road of described light emitting diode string by the described pulse signal that receives, restriction flow through described light emitting diode string work the road electric current size and the work size of electric current on road of the described light emitting diode string of flowing through detected, work after the electric current on road exceeds threshold value in the described described light emitting diode string of flowing through, sent flow control signals to described pulsewidth regulation and control unit;
Described pulsewidth regulation and control unit also be used for receive described cross flow control signals after, send shutdown signal to described current-limiting protection unit, to turn-off the described light emitting diode string road of working.
2. light-emitting diode Drive and Control Circuit according to claim 1, it is characterized in that, described current-limiting protection unit specifically comprises: light-emitting diode control sub unit, current limliting subelement and overcurrent protection subelement, wherein said light-emitting diode control sub unit is connected with described pulsewidth regulation and control unit with described overcurrent protection subelement, and described current limliting subelement is connected with described light-emitting diode control sub unit by described overcurrent protection subelement;
Described light-emitting diode control sub unit, be used for when described pulse signal is high level, the described light emitting diode string road of working is imported with described voltage signal in the described light emitting diode string of the conducting road of working, and is work each the described light-emitting diode power supply on the road of described light emitting diode string;
Described current limliting subelement, the current value that is used for normal voltage voltage of signals value by changing the described current limliting subelement of input or normalized current signal change and export the work current value of predetermined current signal on road of described light emitting diode string to;
Described overcurrent protection subelement; be used to receive the described predetermined current signal of described current limliting subelement output; and export the described light emitting diode string road of working to; be used for the work current value of the actual current on the road of the current value of the described predetermined current signal of described current limliting subelement output and the described light emitting diode string of flowing through is compared; if the current value of described actual current greater than the current value of described normalized current signal, then sends the described flow control signals of crossing to described pulsewidth regulation and control unit.
3. light-emitting diode Drive and Control Circuit according to claim 2 is characterized in that, described light-emitting diode control sub unit specifically comprises: first switch element, first resistance and first voltage-stabiliser tube,
The first input end of described first switch element connects the output of described pulsewidth regulation and control unit, be used to receive described pulse signal, second input of described first switch element connects an end of described first resistance, the other end of described first resistance is imported described voltage signal, the described light emitting diode string that one group of described light-emitting diode forms of being connected in series the output of described first switch element road of working, the output of described first switch element connects an end of described first voltage-stabiliser tube, the other end ground connection of described first voltage-stabiliser tube.
4. light-emitting diode Drive and Control Circuit according to claim 3 is characterized in that, described current limliting subelement specifically comprises: current limliting input, second voltage-stabiliser tube, the 3rd resistance, the 4th resistance, first operational amplifier and second switch element,
Described current limliting input connects the positive input of described first operational amplifier and imports described normal voltage signal or described normalized current signal; One end of described second voltage-stabiliser tube connects described current limliting input, the other end ground connection of described second voltage-stabiliser tube; One end of described the 3rd resistance connects the negative input of described first operational amplifier, and an end of described the 4th resistance connects described current limliting input, and the other end of the other end of described the 3rd resistance and described the 4th resistance is ground connection respectively; The output of described first operational amplifier connects the input of described second switch element, first output of described second switch element connects the negative input of described first operational amplifier, and second output of described second switch element is exported described predetermined current signal.
5. light-emitting diode Drive and Control Circuit according to claim 4 is characterized in that, described overcurrent protection subelement specifically comprises: second resistance, the 5th resistance and second operational amplifier,
One end of described second resistance connects the positive input of described second operational amplifier and receives described predetermined current signal, and the other end of described second resistance connects the other end of described first resistance; One end of described the 5th resistance connects the negative input of described second operational amplifier, and the other end of described the 5th resistance connects an end of described first resistance; The output of described second operational amplifier sends the described flow control signals of crossing to described pulsewidth regulation and control unit.
6. according to the arbitrary described light-emitting diode Drive and Control Circuit of claim 1-5, it is characterized in that described pulsewidth regulation and control unit specifically comprises:
Digital pulse width regulation and control unit is used to export adjustable as the work digital pulse signal of switching signal on road of light emitting diode string, carries out light modulation with the light-emitting diode on the road that described light emitting diode string is worked; And/or
Analog pulse width regulation and control unit is used to export adjustable as the work analog pulse signal of switching signal on road of light emitting diode string, carries out light modulation with the light-emitting diode on the road that described light emitting diode string is worked.
7. light-emitting diode Drive and Control Circuit according to claim 6, it is characterized in that, described analog pulse width regulation and control unit specifically comprises: variable resistor, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, electric capacity, the 3rd operational amplifier, first diode, second diode and the 3rd voltage-stabiliser tube
A described variable-resistance end connects the positive pole of described first diode, and the described variable-resistance other end connects the negative pole of described second diode; The positive pole of the negative pole of described first diode and described second diode is connected an end of described the 9th resistance, and the other end of described the 9th resistance connects an end of described electric capacity, the other end ground connection of described electric capacity; The negative input of described the 3rd operational amplifier connects an end of described electric capacity, the positive input of described the 3rd operational amplifier connects an end of described the 6th resistance and an end of described the 7th resistance, and the output of described the 3rd operational amplifier connects an end of the 8th resistance; The other end ground connection of described the 6th resistance, the other end of the other end of described the 7th resistance and described the 8th resistance is connected described variable-resistance convertible tip, and exports described analog pulse signal; One end of described the 3rd voltage-stabiliser tube connects the other end of described the 7th resistance, and the other end of described the 3rd voltage-stabiliser tube connects the other end of described the 6th resistance;
Wherein,, described electric capacity is carried out the adjusting of charge/discharge, to change the duty ratio of the described analog pulse signal of exporting by described variable-resistance resistance is regulated.
8. light-emitting diode Drive and Control Circuit according to claim 6; it is characterized in that; also comprise: selected cell; be connected between described pulsewidth regulation and control unit and the described current-limiting protection unit; be connected with described analog pulse width regulation and control unit with described digital pulse width regulation and control unit, receive and select described digital pulse signal of output or described analog pulse signal.
9. light-emitting diode Drive and Control Circuit according to claim 8; it is characterized in that; also comprise: switch element; be connected between described selected cell and the described current-limiting protection unit, be used for selecting the described digital pulse signal or the described analog pulse signal of output to amplify described selected cell.
10. a light-emitting diode drive controlling method is characterized in that, comprising:
The output of pulsewidth regulation and control unit is adjustable as the work pulse signal of switching signal on road of light emitting diode string, wherein, importing the work magnitude of voltage of voltage signal on road of described light emitting diode string determines according to the work number of the light-emitting diode that connects on the road of described light emitting diode string;
After the current-limiting protection unit receives the described pulse signal of described pulsewidth regulation and control unit output, control the work conducting on road of described light emitting diode string and carry out light modulation with the light-emitting diode on road that described light emitting diode string is worked;
Described current-limiting protection unit restriction flow through described light emitting diode string work the road electric current size and the work size of electric current on road of the described light emitting diode string of flowing through detected, work after the electric current on road exceeds threshold value in the described described light emitting diode string of flowing through, sent flow control signals to described pulsewidth regulation and control unit;
Described pulsewidth regulation and control unit receive described cross flow control signals after, send shutdown signal to described current-limiting protection unit, to turn-off the described light emitting diode string road of working.
11. light-emitting diode drive controlling method according to claim 10 is characterized in that, described pulsewidth regulation and control unit output is adjustable specifically comprises as the work pulse signal of switching signal on road of light emitting diode string:
The output of digital pulse width regulation and control unit is adjustable as the work digital pulse signal of switching signal on road of light emitting diode string;
The output of analog pulse width regulation and control unit is adjustable as the work analog pulse signal of switching signal on road of light emitting diode string, and the duty ratio of wherein said analog pulse width signal can come the charge/discharge of control capacittance to change by regulating variable-resistance resistance;
Selected cell receives described digital pulse signal and/or described analog pulse signal, and selects described digital pulse signal of output or described analog pulse signal to described current-limiting protection unit;
Then, the described current-limiting protection unit described pulse signal that receives described pulsewidth regulation and control unit output specifically comprises: described current-limiting protection unit receives described digital pulse signal or described analog pulse signal.
12. light-emitting diode drive controlling method according to claim 11; it is characterized in that; after described current-limiting protection unit received described digital pulse signal or described analog pulse signal, the described light emitting diode string of described control worked before the conducting on road, also comprises:
Select the described digital pulse signal or the described analog pulse signal of output to amplify to described selected cell.
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| CN201010152189.8A CN102223743B (en) | 2010-04-16 | 2010-04-16 | Light emitting diode (LED) driving control circuit and method thereof |
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