CN104619087B - Many LED strip drive circuits and its control method - Google Patents
Many LED strip drive circuits and its control method Download PDFInfo
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- CN104619087B CN104619087B CN201510064575.4A CN201510064575A CN104619087B CN 104619087 B CN104619087 B CN 104619087B CN 201510064575 A CN201510064575 A CN 201510064575A CN 104619087 B CN104619087 B CN 104619087B
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Abstract
The present invention relates to a kind of many LED strip drive circuits and its control method.The present invention selects minimum feedback voltage passage by the selecting module, and exports corresponding Continuity signal, and the on-off circuit controlled in the channels in series that the minimum feedback voltage is located is turned on all the time；Pass through the duty cycle control module again, according to the feedback voltage in each channels in series, the on-off circuit interval in remaining each channels in series of control in addition to minimum feedback voltage channels in series is turned on, and makes the average feedback voltage of remaining each channels in series equal with the feedback voltage of minimum feedback voltage channels in series.As the average current of channels in series is relevant to the ratio of average feedback voltage and conducting resistance in channels in series, and the brightness of LED is directly related to the average current size of LED, therefore, it is equal by controlling average feedback voltage in each passage, and then realize that the brightness of string LED is consistent, and extra power consumption is less, system effectiveness is also substantially increased.
Description
Technical field
The present invention relates to a kind of LED control fields, particularly a kind of many LED strip drive circuits and its control method.
Background technology
Widely, profit is as being used as all kinds of computer liquid crystals for application of the light emitting diode (abbreviation LED) in various product
Show backlight, big screen LED advertisement screen etc. in device.
In many applications, generally multiple LED strips are joined, constitutes a LED strip and join branch road, and by drive circuit come same
When or drive several LED strips connection branch road (hereinafter referred to as LED strip) work respectively, due to particularity during LED processing and manufacturings, lead
Cause different the manufacturers even electric current of LED of the same manufacturer produced in a collection of product, voltage characteristic equal
There is larger individual variation.Conducting voltage just because of each LED is different, so the electric current phase of each LED strip will be realized
Deng needing to be adjusted each LED strip.
In prior art, typically connected in each LED strip again a NMOS tube or bipolar transistor, by output services
Voltage VO is adjusted to the minimum running voltage needed for higher than LED, then by adjust the NMOS tube connected on each LED branch road or
The conducting state of bipolar transistor further adjusts its voltage drop, and the unnecessary pressure drop of LED setting electric currents will be maintained to pass through NMOS tube
Or bipolar transistor adjustment is consumed.The shortcoming of this mode is that these NMOS tubes or bipolar transistor are in half conducting state, will
Consume extra efficiency, and multiple LED strips will lower consumption more power, so as to cause system effectiveness low.
The content of the invention
Instant invention overcomes disadvantages mentioned above, there is provided a kind of to be lost little, efficiency high, and realize consistent many of each LED luminance
LED strip drive circuit.
The present invention solves its technical problem and is adopted the technical scheme that：A kind of many LED strip drive circuits, for connection and
Some LED strips are driven, including
Some on-off circuits, for turning on and off the channels in series that each LED strip is located；
Some feedback resistances, for partial pressure and obtain the feedback voltage of place channels in series；
Wherein, an a LED strip, an on-off circuit and feedback resistance channels in series in series；
Also include,
Voltage control circuit, its outfan are connected with each channels in series, for each channels in series offer work
Voltage；
Selecting module, its input are connected with the feedback resistance in each channels in series, and outfan is direct or indirect
It is connected with the control end of the on-off circuit, for minimum feedback voltage is selected in each channels in series, and exports corresponding
Continuity signal, the on-off circuit controlled in the channels in series that the minimum feedback voltage is located turned on all the time；
Control circuit of duty ratio, its input are connected with the feedback resistance in each channels in series, and its outfan is straight
Connect or be connected with the control end of the on-off circuit indirectly, for according to the feedback voltage in each channels in series, control is except most
The on-off circuit interval in remaining each channels in series outside low feedback voltage channels in series is turned on, and makes described remaining each series connection
The average feedback voltage of passage is equal with the feedback voltage of minimum feedback voltage channels in series.
The first error amplifier is may also include, its input connects the minimum feedback voltage outfan of the selecting module,
Its outfan is connected with the voltage control circuit, for the minimum feedback voltage and the benchmark electricity that obtain the selecting module
Pressure compares, and obtains error voltage, and feeds back to the voltage control circuit, and the voltage control circuit is according to error electricity
The running voltage of pressure adjustment output；After circuit stability, the minimum feedback voltage, the average feedback voltage and the base are made
Quasi- voltage is equal.
The selecting module can pass through with the input and Continuity signal outfan with the equal number of the channels in series
The input obtains the feedback voltage of each channels in series, and the minimum feedback voltage for therefrom obtaining, and controls minimum anti-with described
The corresponding Continuity signal outfan output useful signal of feedthrough voltage channels in series, remaining Continuity signal outfan export invalid letter
Number；
The control circuit of duty ratio can with some duty cycle control modules of the channels in series number identical, respectively
The connection corresponding with the feedback resistance in each channels in series respectively of the input of duty cycle control module, each Duty ratio control
The outfan of module, according to the feedback voltage in the corresponding channels in series for receiving, exports corresponding duty by its outfan
Compare signal；
Many LED strip drive circuits may also include some logic gates, correspond respectively to each channels in series, each institute
State logic gates and there is first input end, the second input and outfan, the outfan with corresponding channels in series
The control end of on-off circuit is connected, and the first input end is connected with the outfan of the corresponding duty cycle control module
Connect, second outfan is connected with the Continuity signal outfan of the corresponding selecting module；
Any one for each gate, in its described Continuity signal and the duty cycle signals for receiving
For it is effective when, the logic gates output control signal controls corresponding on-off circuit conducting, otherwise, output control signal control
Corresponding on-off circuit cut-off.
The selecting module can also have an initializing signal outfan, and it is first that the initializing signal outfan is exported
Beginningization signal continues section time effective pulse signal for one；
Each described logic gates also has the 3rd input, and the 3rd input is initial with the selecting module
Change signal output part to be connected；For each logic gates, believe in the initializing signal, Continuity signal and dutycycle
When any one in number is output as effective, the logic gates output control signal controls corresponding on-off circuit conducting, otherwise,
Output control signal controls corresponding on-off circuit cut-off.
The selecting module can further include comparison module and the output module being sequentially connected with；The comparison module, uses
In the feedback voltage of each channels in series of comparison, the channels in series that minimum feedback voltage is located, the output module, for root are obtained
Corresponding Continuity signal is exported according to the channels in series that minimum feedback voltage is located, and minimum feedback voltage is exported.
The selecting module may also include initialization module, and the initialization module is used to provide initializing signal, and which is defeated
The clock signal for going out is directly or indirectly connected to the control end of the on-off circuit；The initialization letter of the initialization module output
Number for a continuous and effective time period, in effective period of time starting, the on-off circuit controlled in each channels in series is led
It is logical, and by the feedback voltage of the more each channels in series of the comparison module, the channels in series that minimum feedback voltage is located is obtained,
At the end of the effective period of time, led according to the passage output that minimum feedback voltage is located accordingly by the output module
Messenger.
Each described duty cycle control module may include wave filter, the second error amplifier and the comparator being sequentially connected with,
Second error amplifier, one input is connected with the outfan of the wave filter, and another input is accessed with reference to electricity
Pressure, outfan are connected to an input of the comparator, and another input of the comparator accesses triangular signal, defeated
Go out outfan of the end i.e. as control circuit of duty ratio.
Each described logic gates can be OR gate, and the input of each OR gate connects the initial of the selecting module respectively
Change the outfan of signal output part, one of Continuity signal outfan and a control circuit of duty ratio, the OR gate
Outfan connect the control end of the corresponding channels in series breaker in middle circuit；The initializing signal is represented when being high level
Effectively, represent effective when the duty cycle signals are high level, the Continuity signal represents effective when being high level, the OR gate
When being output as high level, its corresponding on-off circuit conducting, when the OR gate is output as low level, its corresponding on-off circuit cuts
Only.
A kind of many LED strip drive control methods, comprise the steps：
The channels in series that each LED strip is located is all turned on；
Obtain the feedback voltage of each channels in series, relatively and select minimum feedback voltage in each channels in series；
The minimum channels in series of control feedback voltage is turned on all the time, according to feedback voltage and the reference of remaining each channels in series
Voltage, produces duty cycle signals, and control correspondence channels in series interval is turned on, and makes the average feedback of remaining each channels in series
Voltage is equal with the feedback voltage of minimum feedback voltage channels in series.
The step of channels in series that each LED strip is located is all turned on, can further include following steps：
When electricity on circuit or when being enabled, an initializing signal is produced,
An optional channels in series, and the current feedback voltage of the channels in series is obtained,
Current feedback voltage is compared with reference voltage, is obtained error voltage, and is produced work according to the error voltage
Make voltage, be that each channels in series is powered；
In the feedback voltage for obtaining each channels in series, relatively and minimum feedback voltage step in each channels in series is selected
After rapid, the step of also end including initializing signal.
In the feedback voltage for obtaining each channels in series, relatively and minimum feedback voltage step in each channels in series is selected
After rapid, may also include and be compared with reference voltage according to the minimum feedback voltage, obtain error voltage, and adjust work
The step of voltage.
The present invention selects minimum feedback voltage passage by the selecting module, and exports corresponding Continuity signal, controls
On-off circuit in the channels in series that the minimum feedback voltage is located is turned on all the time；Again by the duty cycle control module,
According to the feedback voltage in each channels in series, the institute in remaining each channels in series in addition to minimum feedback voltage channels in series is controlled
State on-off circuit interval to turn on, make the average feedback voltage and minimum feedback voltage channels in series of remaining each channels in series
Feedback voltage is equal.As the average current of channels in series is relevant to the ratio of conducting resistance in average feedback voltage and channels in series
Value, and the brightness of LED is directly related to the average current size of LED, therefore, by controlling average feedback voltage in each passage
It is equal, and then realize that the brightness of string LED is consistent, and also extra power consumption is less, also substantially increases system effectiveness.
Description of the drawings
Fig. 1 is the circuit theory diagrams of many LED strip drive circuits in the present invention；
Fig. 2 is the circuit theory diagrams of duty cycle control module in Fig. 1；
Fig. 3 is the oscillogram of each output signal in the duty cycle control module；
Fig. 4 is the circuit theory diagrams of selecting module in Fig. 1；
Fig. 5 is the flow chart of many LED strip drive control methods in the present invention.
Specific embodiment
The invention provides a kind of many LED strip drive circuits, for connecting and driving several LED strips.
As shown in fig. 1, a kind of circuit theory of preferred implementation of many LED strip drive circuits for providing for the present invention
Figure, in the present embodiment, many LED strip drive circuits are used to drive three LED strips, each LED strip to be formed by three LED strip connection, respectively
It is the first LED strip being in series by LED1A, LED1B and LED1C, second be in series by LED2A, LED2B and LED2C
LED strip, the 3rd LED strip being in series by LED3A, LED3B and LED3C.The LED strip can be reduced to one it is single
LED, or can also be other series-parallel systems.
This preferred embodiment includes three on-off circuits for joining branch road for turning on and off each LED strip, and is used for partial pressure
And three feedback resistances of the feedback voltage of place channels in series are obtained, the on-off circuit includes corresponding with LED strip number
Three nmos pass transistors, an one group of LED strip, an on-off circuit and feedback resistance channels in series in series, i.e.,
One LED strip, nmos pass transistor MN1 and feedback resistance R1 series connection, constitute the first channels in series, other channels in series by that analogy,
Second LED strip, nmos pass transistor MN2 and feedback resistance R2 series connection, constitutes the second channels in series, the 3rd LED strip, nmos pass transistor
MN3 and feedback resistance R3 series connection, constitutes the 3rd channels in series.Wherein, the resistance value of resistance R1～R3 is identical, is r.This is preferably
Embodiment is also including voltage control circuit U1, selecting module U2, control circuit of duty ratio, error amplifier EA and gate electricity
Road.
The input connection power voltage terminal VIN of the voltage control circuit U1, outfan VO are connected to each series connection
The voltage input end of passage, and running voltage is provided to each channels in series.
Selecting module U2 is with the input with the equal number of the channels in series (being three in the present embodiment)
FB1, FB2, FB3 and Continuity signal outfan ON1, ON2, ON3, minimum feedback voltage outfan Min, an initialization letter
Number outfan Init.Feedback resistance R1 in input FB1, FB2, FB3 of selecting module U2 and each channels in series,
R2, R3 are connected, for obtaining the feedback voltage of each channels in series in each channels in series, and by the minimum feedback for therefrom obtaining
Voltage, while being exported by the Continuity signal in Continuity signal outfan ON1, ON2, ON3 corresponding to minimum feedback voltage passage
End output useful signal, the on-off circuit controlled in the minimum feedback voltage place channels in series are turned on all the time, remaining conducting
Signal output part exports invalid signals；Again minimum feedback voltage is exported to error from the minimum feedback voltage outfan Min
The input of amplifier EA, the error voltage that the outfan of the error amplifier EA is connected to the voltage control circuit U1 are defeated
Enter to hold EAO, for the minimum feedback voltage that the selecting module is obtained is compared with reference voltage, the error voltage that will be obtained
The voltage control circuit is fed back to, the voltage control circuit adjusts the running voltage of output according to the error voltage.
The control circuit of duty ratio include the number of duty cycle control module AvgReg1, AvgReg2, AvgReg3 also with
Channels in series number is identical, feedback resistance R1, R2, the R3 in the input of each duty cycle control module and each channels in series
It is connected, outfan Jing logic gates is connected to the control end of the nmos pass transistor.According to the feedback in each channels in series
Voltage, the on-off circuit interval controlled in remaining each channels in series in addition to minimum feedback voltage channels in series are turned on,
After whole circuit stability, the average feedback voltage of remaining each channels in series and the feedback of minimum feedback voltage channels in series are made
Voltage is equal, and equal with the reference voltage.
The logic gates is by the output of the selecting module and duty cycle control module for controlling the switch
The control signal of circuit (i.e. nmos pass transistor), the control end of corresponding access each channels in series breaker in middle circuit, i.e.,
The grid of nmos pass transistor, which includes three OR gates OR1, OR2, OR3.Three inputs of the OR gate OR1 connect choosing respectively
Select the output of initializing signal outfan Init, Continuity signal outfan ON1 and the duty cycle control module AvgReg1 of module U2
End, outfan are connected to the grid of the nmos pass transistor MN1, and by that analogy, three inputs of the OR gate OR2 connect respectively
Meet initializing signal outfan Init, Continuity signal outfan ON2 and the duty cycle control module AvgReg2 of selecting module U2
Outfan, outfan are connected to the grid of the nmos pass transistor MN2；Three inputs of the OR gate OR3 connect choosing respectively
Select the output of initializing signal outfan Init, Continuity signal outfan ON3 and the duty cycle control module AvgReg3 of module U2
End, outfan are connected to the grid of the nmos pass transistor MN3, when appointing in the signal of three inputs input of OR gate
One for it is effective when, control the conducting of corresponding on-off circuit.
Based on foregoing circuit structure, its course of work is as follows：
First, the initializing signal outfan Init of selecting module U2 exports an initializing signal, when every secondary circuit electricity
Electricity or initializing signal is produced when being enabled on source, i.e., when power supply electrifying or when being enabled, Init ends become high level, continue one
The section time, then become low level.The now output of the high level signal Jing OR gate OR1, OR2, OR3 to nmos pass transistor MN1,
The grid of MN2, MN3 is all changed into high level, and switch MN1～MN3 is all turned on, and all turns on all channels in series.
Now selecting module U2 selects the feedback voltage of any channels in series (i.e. any in input FB1～FB3
One) export to minimum feedback voltage outfan Min, loop feedback control is carried out, although as current each channels in series is in
Conducting state, but now voltage control circuit U1 does not have output services voltage, and each channels in series electric current is zero, therefore this is anti-
Feedthrough voltage is that error amplifier EA is compared with reference voltage VR described in 0, Jing, and the error voltage (equivalent to VR) of generation is input to institute
The error voltage input EAO of voltage control circuit U1 is stated, then the voltage control circuit U1 produces work according to error voltage
Make voltage, powered for LED strip by voltage output end VO.This process is to utilize negative feedback, makes voltage control circuit and LED strip
Working condition is entered from off state.Wherein, the voltage control circuit U1 can adopt Boost DC-direct current conversion and control
Device, buck DC to dc switching controller or AC-DC switching controller are realizing.
Now selecting module U2 compares the feedback voltage of three inputs FB1, FB2, FB3, i.e. find out feedback voltage
That minimum channels in series, then exports minimum feedback voltage to minimum feedback voltage outfan MIN, and controls corresponding
The Continuity signal outfan output high level of channels in series, other Continuity signal outfans are low level.Such as described selection mould
Block U2 judges that the feedback voltage (i.e. the feedback voltage of input FB1) of the first channels in series is minimum, then by the electricity of input FB1
Pressure output is to minimum feedback voltage outfan Min, and Continuity signal outfan ON1 is set to high level, and other two is turned on
Signal output part ON2 and ON3 are set to low level.
Wherein, the initializing signal of the initializing signal outfan Init outputs of selecting module U2, is a high electricity
The flat time period (i.e. high level is effective), it is used for selecting minimum feedback voltage channels in series, when the time period starting
When, i.e., when the saltus step of initializing signal outfan is high level, the switch in each channels in series is controlled by the logic gates
Circuit turn-on, and it is used for the control of loop with the feedback voltage of optional channels in series, by realizing this with error amplifier EA
Feedback voltage is compared with reference voltage VR, produces error voltage, and the voltage control circuit U1 is produced according to the error voltage
And running voltage is adjusted, by voltage output end VO, it is that LED strip is powered, then by the more each channels in series of the comparison module
Feedback voltage, obtain the channels in series that minimum feedback voltage is located.At the end of the time period, i.e. initializing signal outfan
When saltus step is low level, corresponding Continuity signal is exported according to the passage that minimum feedback voltage is located by the output module.
This high level time section is used to judging and selecting minimum feedback voltage and minimum feedback voltage channels in series, the afterwards initialization
Signal output part is low level always.
Then, the high level signal of the Continuity signal outfan ON1 outputs of selecting module U2, Jing OR gates OR1 controls
The nmos pass transistor MN1 is constantly on (being 100% i.e. equivalent to its dutycycle), and feedback voltage minimum means this branch road
The series connection conducting voltage of LED strip is maximum, when the nmos pass transistor MN1 it is constantly on, after amenorrhea ring feedback, the first channels in series
Feedback voltage be equal to reference voltage VR, the electric current of this first LED strip is constantly equal to VR/r.And the other two of selecting module U2 is led
Messenger outfan ON2 and ON3 are low level, are now believed by duty cycle control module AvgReg2, AvgReg3 output duty cycle
Number, OR gate OR2, OR3 described in Jing make this two-way series connection logical controlling nmos pass transistor MN2, MN3 in other two channels in series
Road batch (-type) conducting, leads to as the conducting voltage of LED strip in the two channels in series is below the minimum feedback voltage series connection
The series connection conducting voltage of the LED strip in road, adjusts nmos pass transistor by the duty cycle control module and turns on period dutycycle
Less than 1, and the average voltage of feedback voltage is met equal to reference voltage VR, then the LED strip of remaining two channels in series is flat
Electric current is also equal to VR/r.
As shown in Fig. 2 for the schematic diagram of duty cycle control module in this preferred embodiment, the duty cycle control module bag
Wave filter Filter, the second error amplifier OP and comparator Comp being sequentially connected with is included, wherein, the input of the wave filter
It is connected with the feedback resistance, obtains feedback voltage, outfan is connected to the anti-phase input of the second error amplifier OP
Reference voltage VR is accessed at end, the in-phase input end of the second error amplifier OP, and outfan is connected to the comparator Comp
In-phase input end, the inverting input of the comparator Comp accesses triangular signal.The error amplifier and comparator
Peripheral circuit be routine techniquess, not shown in figure, those skilled in the art can be designed and suitably according to actual needs
Choose.
The specific work process of the duty cycle control module is as follows, the feedback voltage signal of each channels in series, Jing
Average-voltage signal AVFB is produced after wave filter Filter filtering, the wave filter Filter will be the signal waveform being input into whole
Shape, makes this waveform more stable, so as to the second error amplifier OP steady operations.The wave filter Filter can adopt conventional
Various low pass filters, such as RC wave filter or other low-pass active filters, belong to routine techniquess, omit herein and specifically retouch
State.Average-voltage signal AVFB is compared by the second error amplifier OP with reference voltage VR, according to their voltage difference
Error signal OPO is produced, error signal OPO is compared by the comparator Comp with triangular signal Ramp, produce phase
The duty cycle signals D for answering, then export to corresponding logic gates.
When the average-voltage signal AVFB voltages are higher than reference voltage VR, error amplifier OP reduces the error of its output
The dutycycle reduced to reduce duty cycle signals D of signal OPO, comparator Comp according to error signal OPO, with reference to knowable to Fig. 1,
When the dutycycle of the duty cycle signals D reduces, after OR gate, cause leading for corresponding on-off circuit, i.e. nmos pass transistor
The logical time reduces, and so causes the high level time of corresponding voltage feedback signal to reduce, further results in through low-pass filtering
Average-voltage signal AVFB signals after device Filter reduce, and result in formation of negative feedback.Conversely, working as the average-voltage signal
When AVFB signals are less than reference voltage VR, error amplifier OP increases error signal OPO of its output, causes the comparator
The dutycycle of Comp output signals D increases, and causes the signal dutyfactor after OR gate to increase, and controls corresponding nmos pass transistor
ON time increases, and so as to the high level time for causing corresponding feedback voltage signal increases, further results in through low pass filtered
Average-voltage signal AVFB signals after ripple device Filter increase, and also show as negative feedback.It is when this feedback loop is stable, inevitable
Meet average-voltage signal AVFB equal with reference voltage VR.So when final all control loops are stablized, the electricity of each LED strip
The meansigma methodss of stream are equal to VR/r, therefore, as long as arranging resistance all phases of feedback resistance R1, R2, the R3 in all channels in series
Together, then can realize that the average current of all LED strips is all equal.
As shown in Figure 3, be each output signal in the duty cycle control module oscillogram, Ramp is periodic triangular
Ripple signal, in one cycle, when, in time period of error signal OPO higher than Ramp signals, duty cycle signals D is high level；
In a cycle, when, in time period of error signal OPO less than Ramp signals, duty cycle signals D is low level.Illustrate in figure
The rising time of Ramp signals is longer, the trailing edge time shorter (almost nil), but in actual design, it is also possible in design
Rise shorter along the time, the trailing edge time is longer.
As shown in Figure 4, be selecting module described in this preferred embodiment circuit theory diagrams.The selecting module includes
Comparison module, output module and initialization module, the comparison module are used for the feedback voltage of each channels in series of comparison, obtain most
The channels in series of little feedback voltage, the output module are exported for the feedback voltage by the channels in series of minimum feedback voltage
Corresponding Continuity signal, and minimum feedback voltage is exported.The initialization module, for providing starting clock signal, which is defeated
Logic gates described in clock signal Jing for going out is connected to the control end of the on-off circuit.
The comparison module include comparator CM1～CM3, phase inverter inv1, nor gate nor1, nor2 and with door and1.
The feedback voltage of three channels in series is respectively connected to the input of three comparators, when the feedback voltage signal of the first channels in series
When FB1 voltages are minimum, the outfan MIN1 of OR gate nor1 is high level, and outfan MIN2 and MIN3 are low level.When the first string
When the feedback voltage signal FB2 voltages in UNICOM road are minimum, the outfan MIN2 with door and1 is high level, and MIN1 and MIN3 is low
Level.When the voltage of the feedback voltage signal FB3 of the 3rd channels in series is minimum, the outfan MIN3 of nor gate nor2 is high electricity
Flat, MIN1 and MIN2 is low level.Three output signals MIN1, MIN2, MIN3 be respectively outputted to three d type flip flop ffdf1～
The d ends of ffdf3, when TL signal trailing edges, MIN1～MIN3 signal latches are touched by the d type flip flop ffdf1～ffdf3 to D
The q ends of device are sent out, and as the Continuity signal outfan ON1～ON3 of the selecting module.
Feedback voltage signal FB1, FB2, FB3 of three channels in series is respectively through three switch S1, S2, S3 outputs to institute
Minimum feedback voltage outfan MIN ends are stated, when initializing signal Init signals are high level, by OR gate OR4 controlling switches
S1 is turned on, and selects the feedback voltage signal FB1 outputs of the first channels in series to MIN outfans, due to this selection be it is arbitrary,
FB2 or FB3 outputs can also be selected to MIN ends.After Init signals are low level, the defeated of high level in ON1～ON3, is output as
Go out end, it is corresponding to be the minimum channels in series of feedback voltage, and switched minimum accordingly in controlling switch S1, S2, S3
Feedback voltage signal output is to MIN ends.
The initialization module includes resistance R4, R5, comparator CM4, phase inverter INV2, OR gate OR5 and four concatenations
D type flip flop ffdf4～ffdf7.Here the number of d type flip flop is simply illustrated, and can increase as the case may be in actual design
Add deduct little d type flip flop number, and the number of d type flip flop determines the time that initializing signal Init is high level, and number is more,
Init is longer for the time of high level.Input supply voltage VIN is carried out partial pressure by described resistance R2, R1, then by comparator
CM4 is compared with reference voltage VRUV, produces UV signals, when input supply voltage is less than VRUV × (R4+R5)/R5, UV signals
For high level, therefore the minimum running voltage of circuit is provided with by the partial pressure of resistance R4, R5.When supply voltage power up
In, can typically there is one section of virtual voltage less than VRUV × (R4+R5)/R5, i.e., the time period of minimum running voltage, now produce
A period of time UV is high level state, produces reset signal RST of all d type flip flops through OR gate OR5.Or when circuit is enabled
Signal EN be low level when, after phase inverter INV2 be high level, through OR gate OR5 RST signal also be high level.So
Circuit is prohibited work or supply voltage power up can all produce reset signal, i.e. RST signal for high level, all D triggerings
Device resets for high level, the outfan q of all d type flip flops can be reset to low level, outfan qb is reset to high level.
CK is clock signal, can be produced by any oscillator structure.
The TL signals of the 3rd d type flip flop ffdf6 outputs, are high electricity in four clock cycle after circuit is started working
It is flat, low level will be changed in the trailing edge of the 4th clock cycle.4th d type flip flop ffdf7 output and Init signals in electricity
It is high level in eight clock cycle after the start-up operation of road, low level will be changed in the trailing edge of the 8th clock cycle.It is described
TL signals are used for generation and the selection result of minimum feedback voltage channels in series are latched into d type flip flop ffdf1, ffdf2, ffdf3
In time point, in order to ensure correctly to select minimum feedback Voltage Series passage, Init signals should for time of high level
Continue until that the trailing edge of TL signals arrives, i.e., the trailing edge of initializing signal Init signals should be later than the trailing edge of TL signals,
Specific time delay can be produced by analog delay circuit, it is also possible to produced by digital circuit.Concrete time delay can be with root
According to being actually needed free setting.
As shown in Figure 5, the flow chart of many LED strip drive control methods for providing for the present invention, comprises the steps：
1st, when electricity on circuit or when being enabled, an initializing signal is produced, as the whole starting clock for driving process
Signal, the initializing signal can be the time period of a high level；
2nd, an optional channels in series, and obtain the current feedback voltage of the channels in series；
3rd, it is compared according to the feedback voltage and reference voltage, obtains error voltage, and according to the error voltage
Produce running voltage to power for channels in series；As each channels in series electric current is zero before, this process is to utilize negative feedback,
The channels in series comprising LED strip is made to enter working condition from off state；
4th, obtain the feedback voltage of each channels in series, relatively and select minimum feedback voltage in each channels in series；
5th, it is compared according to minimum feedback voltage and reference voltage, obtains error voltage, and adjust the defeated of running voltage
Go out；
6th, initializing signal terminates, i.e., initializing signal is low level by high level saltus step；
7th, control the minimum channels in series of feedback voltage to turn on all the time, according to the feedback voltage and ginseng of remaining each channels in series
Voltage is examined, duty cycle signals are produced, remaining channels in series interval is controlled and is turned on, and make the average anti-of remaining each channels in series
Feedthrough voltage is equal with the feedback voltage of minimum feedback voltage channels in series.
Above many LED strip drive circuits provided by the present invention and its control method are described in detail, herein
Apply specific case to be set forth the principle and embodiment of the present invention, the explanation of above example is only intended to help
Understand the method for the present invention and its core concept；Simultaneously for one of ordinary skill in the art, according to the thought of the present invention,
Will change in specific embodiments and applications, in sum, this specification content is should not be construed as to this
The restriction of invention.
Claims (10)
1. a kind of many LED strip drive circuits, for connecting and driving some LED strips, it is characterised in that：Including
Some on-off circuits, for turning on and off the channels in series that each LED strip is located；
Some feedback resistances, for obtaining the feedback voltage of place channels in series；
Wherein, an a LED strip, an on-off circuit and feedback resistance channels in series in series；
Also include,
Voltage control circuit, its outfan are connected with each channels in series, for providing running voltage to each channels in series；
Selecting module, its input are connected with the feedback resistance in each channels in series, and outfan is directly or indirectly and institute
The control end for stating on-off circuit is connected, for selecting minimum feedback voltage, and output to lead accordingly in each channels in series
Messenger, the on-off circuit controlled in the channels in series that the minimum feedback voltage is located are turned on all the time；
Control circuit of duty ratio, its input are connected with the feedback resistance in each channels in series, its outfan directly or
It is connected with the control end of the on-off circuit indirectly, for according to the feedback voltage in each channels in series, control is except minimum anti-
The on-off circuit interval in remaining each channels in series outside feedthrough voltage channels in series is turned on, and makes described remaining each channels in series
Average feedback voltage it is equal with the feedback voltage of minimum feedback voltage channels in series.
2. many LED strip drive circuits according to claim 1, it is characterised in that：Also include the first error amplifier, which is defeated
Enter the minimum feedback voltage outfan of the end connection selecting module, its outfan is connected with the voltage control circuit, is used
In the minimum feedback voltage that the selecting module is obtained is compared with reference voltage, error voltage is obtained, and feeds back to described
Voltage control circuit, the voltage control circuit adjust the running voltage of output according to the error voltage；After circuit stability,
Make the minimum feedback voltage, the average feedback voltage equal with the reference voltage.
3. many LED strip drive circuits according to claim 1, it is characterised in that：
The selecting module with the input and Continuity signal outfan with the equal number of the channels in series, by described defeated
Enter the feedback voltage that end obtains each channels in series, and the minimum feedback voltage for therefrom obtaining, control and the minimum feedback voltage
The corresponding Continuity signal outfan output useful signal of channels in series, remaining Continuity signal outfan export invalid signals；
The control circuit of duty ratio with some duty cycle control modules of the channels in series number identical, each dutycycle
The connection corresponding with the feedback resistance in each channels in series respectively of the input of control module, each duty cycle control module root
According to the feedback voltage in the corresponding channels in series for receiving, corresponding duty cycle signals are exported by its outfan；
Many LED strip drive circuits also include some logic gates, correspond respectively to each channels in series, each described logic
Gate circuit has first input end, the second input and outfan, the outfan and the switch electricity in corresponding channels in series
The control end on road is connected, and the first input end is connected with the outfan of the corresponding duty cycle control module, described
Second outfan is connected with the Continuity signal outfan of the corresponding selecting module；
For each gate, any one in its described Continuity signal and the duty cycle signals for receiving is have
During effect, the logic gates output control signal controls corresponding on-off circuit conducting, otherwise, output control signal control correspondence
On-off circuit cut-off.
4. many LED strip drive circuits according to claim 3, it is characterised in that：The selecting module is also with the beginning of one
Beginningization signal output part, the initializing signal of the initializing signal outfan output is the time period pulse of a continuous and effective
Signal；
The initialization that each described logic gates also has the 3rd input, the 3rd input and the selecting module is believed
Number outfan is connected；
For each logic gates, any one in the initializing signal, Continuity signal and duty cycle signals is defeated
Go out for it is effective when, the logic gates output control signal controls corresponding on-off circuit conducting, otherwise, output control signal control
Make corresponding on-off circuit cut-off.
5. many LED strip drive circuits according to claim 4, it is characterised in that：
Each described logic gates is OR gate, and the input of each OR gate connects the initializing signal of the selecting module respectively
The outfan of outfan, one of Continuity signal outfan and a control circuit of duty ratio, the output of the OR gate
The control end of the corresponding channels in series breaker in middle circuit of end connection；
The initializing signal represents effective when being high level, and the duty cycle signals represent effective when being high level, described to lead
Messenger represents effective when being high level, when the OR gate is output as high level, its corresponding on-off circuit conducting, and the OR gate
When being output as low level, its corresponding on-off circuit cut-off.
6. many LED strip drive circuits according to claim 3, it is characterised in that：Each duty cycle control module includes suitable
The wave filter of secondary connection, the second error amplifier and comparator, second error amplifier, one input and the filtering
The outfan of device is connected, and another input accesses reference voltage, and outfan is connected to an input of the comparator,
Another input of the comparator accesses triangular signal, outfan of the outfan i.e. as control circuit of duty ratio.
7. many LED strip drive circuits according to any one of claim 1～6, it is characterised in that：The selecting module is entered
One step includes the comparison module being sequentially connected with and output module；The comparison module, for the feedback electricity of each channels in series of comparison
Pressure, obtains the channels in series that minimum feedback voltage is located, the output module, for the series connection being located according to minimum feedback voltage
Passage exports corresponding Continuity signal, and minimum feedback voltage is exported.
8. a kind of many LED strip drive control methods, comprise the steps：
The channels in series that each LED strip is located is all turned on；
Obtain the feedback voltage of each channels in series, relatively and select minimum feedback voltage in each channels in series；
The minimum channels in series of control feedback voltage is turned on all the time, according to the feedback voltage of remaining each channels in series and with reference to electricity
Pressure, produces duty cycle signals, and control correspondence channels in series interval is turned on, and makes the average feedback electricity of remaining each channels in series
Pressure is equal with the feedback voltage of minimum feedback voltage channels in series.
9. many LED strip drive control methods according to claim 8, it is characterised in that：The series connection that each LED strip is located
The step of passage is all turned on, further includes following steps：
When electricity on circuit or when being enabled, an initializing signal is produced,
An optional channels in series, and the current feedback voltage of the channels in series is obtained,
Current feedback voltage is compared with reference voltage, obtains error voltage, and according to error voltage generation work electricity
Pressure, is that each channels in series is powered；
In the feedback voltage for obtaining each channels in series, relatively and select minimum feedback voltage step in each channels in series it
Afterwards, the step of also terminating including initializing signal.
10. many LED strip drive control methods according to claim 8 or claim 9, it is characterised in that：Each series connection is obtained described
The feedback voltage of passage, relatively and after selecting minimum feedback voltage step in each channels in series, also includes according to most
Low feedback voltage is compared with reference voltage, obtains error voltage, and the step of adjust running voltage.
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| CN101917809A (en) * | 2010-08-24 | 2010-12-15 | 成都芯源系统有限公司 | Driver for driving a plurality of luminescent elements, driving method and display equipment |
| CN102340908A (en) * | 2010-07-23 | 2012-02-01 | 原景科技股份有限公司 | Light emitting diode circuit and operation method thereof |
| CN204350419U (en) * | 2015-02-06 | 2015-05-20 | 无锡中星微电子有限公司 | Many LED strip drive circuit |
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| CN2831680Y (en) * | 2005-09-20 | 2006-10-25 | 复旦大学 | Direct high voltage power supplied series LED constant current driving circuit |
| KR100679410B1 (en) * | 2006-04-04 | 2007-02-06 | 엘지.필립스 엘시디 주식회사 | Device for driving light emitting diode |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102340908A (en) * | 2010-07-23 | 2012-02-01 | 原景科技股份有限公司 | Light emitting diode circuit and operation method thereof |
| CN101917809A (en) * | 2010-08-24 | 2010-12-15 | 成都芯源系统有限公司 | Driver for driving a plurality of luminescent elements, driving method and display equipment |
| CN204350419U (en) * | 2015-02-06 | 2015-05-20 | 无锡中星微电子有限公司 | Many LED strip drive circuit |
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