CN201927327U - LED driving circuit and output circuit thereof - Google Patents
LED driving circuit and output circuit thereof Download PDFInfo
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- CN201927327U CN201927327U CN2010205350475U CN201020535047U CN201927327U CN 201927327 U CN201927327 U CN 201927327U CN 2010205350475 U CN2010205350475 U CN 2010205350475U CN 201020535047 U CN201020535047 U CN 201020535047U CN 201927327 U CN201927327 U CN 201927327U
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Abstract
The utility model discloses an LED driving circuit and an output circuit thereof, wherein the output circuit comprises a benchmark current confirming unit with a control end and a bias end, a plurality of current driving pipes and an output pipe; wherein a first benchmark current or a second benchmark current is selected by the benchmark current confirming unit according to control signals of the control end, and a bias voltage generated according to the selected benchmark current is output by the bias end; source electrodes of the current driving pipes are connected with one another, and drain electrodes of the current driving pipes are connected with one another; wherein a grid electrode of one current driving pipe is directly connected with the bias end, and grid electrodes of the other current driving pipes are connected with the bias end through a switch circuit; a source electrode of the output pipe is connected with the drain electrodes of the current driving pipes, and a drain electrode of the output pipe is used as the output end of the output circuit; and a grid electrode of the output pipe controls the conduction and cutoff of the output pipe. Therefore, based on two different kinds of benchmark current, the output circuit can produce output current so as to expand the adjustment range of the output current and correspond to the light perception law of eyes of people.
Description
[technical field]
The utility model relates to the LED application, especially relates to a kind of led drive circuit and output circuit thereof.
[background technology]
LED(Light Emitting Diode, light emitting diode) because the life-span is long, characteristics such as response speed is fast, volume is little, power consumption is little, reliability height have been widely used in fields such as backlight, illumination, electronic equipment, display screen and automobile.Driving circuit is the important component part of LED product, and the performance of driving circuit will directly have influence on the performances such as life-span, power consumption and reliability of LED product.Usually,, have negative temperature characteristic again, therefore when LED is used as display panel, light fixture or backlight, need adopt constant-current driving LED because LED is the semiconductor devices of characteristic sensitivity.
LED product (such as light-emitting diode display etc.) all comprises the led array of being made up of some LED usually and is used for some driving circuits of driving LED array, wherein each driving circuit includes a plurality of passages (such as 4,8 or 16), and each passage of described driving circuit can provide constant drive current for one or more LED.Be the brightness of each LED and the consistance or the homogeneity of colourity in the assurance led array, each passage of each driving circuit need provide the constant output electric current of accurate unanimity.At present, the interchannel of the driving circuit of main flow (bit-to-bit) electric current difference generally all in ± 3%, and between sheet (chip-to-chip) electric current difference generally all in ± 6%.Precision for the constant output electric current that guarantees led drive circuit, not only need carry out meticulous design and layout in the design link, also need higher manufacturing process to reduce fabrication error as much as possible, this will increase substantially the production and the design cost of led drive circuit.
The reference value of one reference current as output current generally need be provided in led drive circuit inside, and therefore described reference current will directly influence the precision of output current.The precision of described reference current depends on an outer meeting resistance of described led drive circuit.For the consistance of the output current that guarantees the different LED driving circuit, need be within the specific limits with the resistance difference control of the outer meeting resistance of each led drive circuit.Like this, improved requirement, also increased the cost of outer meeting resistance outer meeting resistance.
In addition, the consistance of the brightness of each LED and colourity or homogeneity are not only relevant with the consistance of the output current of led drive circuit in the led array, and be also relevant with the consistance of the optical characteristics (such as luminous flux) of each LED.By way of example, if the output current of each passage of each driving circuit strict conformance all also and certain consistent with colourity once the brightness that guarantees each LED surely, also needs to consider at this moment the consistance of the optical characteristics (such as luminous flux) of each LED.For satisfy more and more higher application demand, just need to adopt higher, stricter production technology can produce the LED that satisfies the demand.Like this, the conforming strict demand to LED causes the yield rate of LED low, cost is high.And the cost proportion of the cost of LED in the LED product occupies very big ratio, and it is high that the cost increase of LED certainly will be arrived the cost that causes some LED products.
Therefore, be necessary to propose a kind of improved technical scheme and overcome the problems referred to above.
[utility model content]
One of the technical problems to be solved in the utility model is to provide a kind of led drive circuit, and it can provide accurately adjustable output current.
Two of the technical problems to be solved in the utility model is to provide a kind of output circuit, and it can utilize simple structure that accurately adjustable output current is provided.
In order to address the above problem, according to an aspect of the present utility model, the utility model provides a kind of output circuit, it comprises: the reference current determining unit with control end and offset side, its control signal according to control end is selected one between first reference current and second reference current, and produce a bias voltage according to selected reference current and export by described offset side, wherein first reference current is less than second reference current; Some current drives pipes, its source electrode is connected to each other, its drain electrode is connected to each other, the grid of one of them current drives pipe directly links to each other with described offset side, the grid of all the other each current drives pipes links to each other with described offset side by an on-off circuit, controls the turn-on and turn-off of corresponding current driving tube by the turn-on and turn-off of controlling each on-off circuit; And efferent duct, its source electrode links to each other with the drain electrode of described current drives pipe, and its drain electrode is as the output terminal of output circuit, and its grid is controlled the turn-on and turn-off of described efferent duct.
Further, the current ratio of first reference current and second reference current is 1:M, wherein 1.5≤M≤4.5.
Further, bias voltage on the described offset side drives each current drives pipe makes it produce output current, and drives the current ratio that ratio that each current drives pipe output current that produces and the bias voltage that produces according to second reference current drive the output current that the corresponding current driving tube produces equals first reference current and second reference current according to the bias voltage that first reference current produces.
Further, the ratio of the breadth length ratio of each current drives pipe of linking to each other with described offset side by on-off circuit of grid is respectively: 2
0: 2
1: ...: 2
Y-2: 2
Y-1, the number of the Y current drives pipe that to be grid link to each other with described offset side by on-off circuit wherein, described output circuit supports 2
Y+1The output current adjustment on rank.The relative breadth length ratio X of the current drives pipe that the direct and described offset side of grid connects satisfies: X+2
0+ 2
1+ ... + 2
Y-2+ 2
Y-1Less than M*X and X+2
0+ 2
1+ ... + 2
Y-2+ 2
Y-1And the every rank electric current adjusting range the when difference between the M*X is less than or equal to second reference current.
Further, according to Y+1 digit current data described output circuit is carried out the output current adjustment, wherein, control the turn-on and turn-off of each on-off circuit according to all the other the Y positions in the current data according to 1 in the current data control signal of determining the control end of described reference current determining unit.
According to another aspect of the present utility model, the utility model provides a kind of led drive circuit, it comprises: control module receives the latch enable signal that the latch enable input end is imported, and judges that according to described latch enable signal current is first mode of operation or second mode of operation; Registers group receives the N bit data that data input pin is imported; N output driver module and N corresponding output circuit, each output driver module drives corresponding output circuit, each output circuit provides output current by the output terminal of correspondence, when first mode of operation, each output driver module starts or stops corresponding output circuit according to 1 bit data of the correspondence in the N bit data in the registers group, when second mode of operation, described N bit data includes the adjustment modes data, current data and channel address data, when the adjustment modes data are adjusted for unification, each output driver module is according to the unified output current of adjusting each output circuit of described current data, when the adjustment modes data are the single channel adjustment, output driver module according to described channel address data enable correspondence, the output driver module that this enables is adjusted the output current of corresponding output circuit separately according to described current data, and N is a natural number.Described each output circuit is one of output circuit of preamble proposition.
Further, N is 4,8,16 or 32.
Further, led drive circuit also comprises: the reference current module, and it provides first reference current and second reference current, and wherein first reference current is less than second reference current.Each output circuit comprises: the reference current determining unit with control end and offset side, its control signal according to control end is selected one between first reference current and second reference current, and produce a bias voltage according to selected reference current and export by described offset side, wherein first reference current is less than second reference current; Some current drives pipes, its source electrode is connected to each other, its drain electrode is connected to each other, the grid of one of them current drives pipe directly links to each other with described offset side, the grid of all the other each current drives pipes links to each other with described offset side by an on-off circuit, controls the turn-on and turn-off of corresponding current driving tube by the turn-on and turn-off of controlling each on-off circuit; And efferent duct, its source electrode links to each other with the drain electrode of described current drives pipe, and its drain electrode is as the output terminal of output circuit, and its grid is controlled the turn-on and turn-off of described efferent duct.Each output driver module starts or stops corresponding output circuit according to 1 bit data of the correspondence in the N bit data in the registers group and is: each output driving circuit is according to the turn-on and turn-off of the efferent duct of the corresponding output circuit of 1 bit data of the correspondence in the N bit data in registers group control; Each output driver module according to the unified output current of adjusting each output circuit of described current data is: each output driver module sends control signal according to 1 in the described current data control end to the reference current determining unit of correspondence, described reference current determining unit is selected one according to described control signal between first reference current and second reference current, each output driver module is controlled the turn-on and turn-off of each on-off circuit in the corresponding output circuit according to the remaining bit in the described current data; The output current that the output driver module that this enables is adjusted corresponding output circuit separately according to described current data is: the output driver module that this enables sends control signal according to 1 control end to described reference current determining unit in the described current data, described reference current determining unit is selected one according to described control signal between first reference current and second reference current, the output driver module that this enables is controlled the turn-on and turn-off of each on-off circuit in the corresponding output circuit according to the remaining bit in the described current data.
Further, each output driver module is all stored described current data before the output current of adjusting corresponding output circuit according to described current data.
Compared with prior art, the led drive circuit in the utility model can provide the single channel of the output current of each current output channels to adjust function and/or the unified function of adjusting.Utilize the unified function of adjusting that the output current of each current output channels is unified to adjust, can reduce greatly even eliminate the output current difference that exists between drive circuit chip, utilizing single channel to adjust function adjusts separately the output current of each current output channels, the output current difference that each interchannel exists can be reduced even eliminate greatly, the brightness that the inconsistency of the optical characteristics (such as luminous flux) owing to LED causes and the inconsistency of colourity can also be reduced or eliminate simultaneously.Output circuit in the utility model produces output current based on two kinds of reference currents that vary in size, and has expanded the setting range of output current like this, and has more met human eye brightness law of perception.
About other purposes of the present utility model, feature and advantage are described in detail in embodiment below in conjunction with accompanying drawing.
[description of drawings]
In conjunction with reaching ensuing detailed description with reference to the accompanying drawings, the utility model will be more readily understood, the structure member that wherein same Reference numeral is corresponding same, wherein:
Fig. 1 is the led drive circuit structural representation block diagram in one embodiment in the utility model;
Fig. 2 is each signal sequence in one embodiment the synoptic diagram of led drive circuit when first mode of operation in the utility model;
Fig. 3 is each signal sequence in one embodiment the synoptic diagram of led drive circuit when second mode of operation in the utility model;
Fig. 4 is the order format exemplary plot in one embodiment that 16 digit currents in the utility model are adjusted data;
Fig. 5 is the output module circuit diagram in one embodiment in the utility model; With
Fig. 6 is the 6 digit current data of the output module among Fig. 5 and the curve synoptic diagram of current gain.
[embodiment]
For above-mentioned purpose of the present utility model, feature and advantage can be become apparent more, the utility model is described in further detail below in conjunction with the drawings and specific embodiments.
Detailed description of the present utility model mainly presents by program, step, logical block, process or other symbolistic descriptions, the running of the technical scheme in its direct or indirect simulation the utility model.Affiliated those of skill in the art use these descriptions herein and state that the others skilled in the art in affiliated field effectively introduce their work essence.
Alleged herein " embodiment " or " embodiment " are meant that special characteristic, structure or the characteristic relevant with described embodiment can be contained at least one implementation of the utility model at least.Different local in this manual " in one embodiment " that occur also nonessentially all refer to same embodiment, must not be yet with other embodiment mutually exclusive separately or select embodiment.In addition, represent the sequence of modules in method, process flow diagram or the functional block diagram of one or more embodiment and revocablely refer to any particular order, also do not constitute restriction of the present utility model.
See also shown in Figure 1, it is the led drive circuit 100 structural representation block diagram in one embodiment in the utility model, and described led drive circuit 100 comprises that control module 110, several output driver modules 120, several output modules 130(also can be called output circuit), reference current module 140 and registers group 150.
Described control module 110 can receive the latch enable signal (latch enable signal) of input end LE input and the output enable control signal (output enable control signal) of input end OE input.Described led drive circuit 100 has two kinds of mode of operations, is respectively first mode of operation and second mode of operation, and wherein first mode of operation also can be called the current drives pattern, and second mode of operation also can be called the electric current adjustment modes.Described control module 110 can enter first mode of operation or enter second mode of operation according to latch enable signal LE judgement is current.
In one embodiment, described registers group 150 includes shift register 151, output register 152 and command register 153.Shift register 151, output register 152 and command register 153 can be the N bit register, and wherein N can be 4,8,16,32 or other natural number.Described shift register 151 can receive the serial data of input end SDI input according to the clock signal of input end CLK input, after described latch enable signal LE comes into force, latch the N bit data in it, and current when being first mode of operation, export described N bit data to described output register 152 as the output enable data,, export described N bit data to described command register 153 and adjust data when being second mode of operation current as electric current.In other embodiments, also output register 152 and command register 153 can be carried out multiplexingly, perhaps shift register 151, output register 152 and command register 153 be carried out multiplexingly, certainly other distressed structure can also be arranged.
Described reference current module 140 links to each other with an outer meeting resistance via input end REXT, it can provide accurate reference current for output module 130, the size of described reference current is determined by described outer meeting resistance, it can provide size two kinds of reference currents simultaneously, their current ratio is 1:M, and 1.5≤M≤4.5 wherein are such as M=2,3,4,1.5 or 2.5 etc., little reference current also can be called as first reference current, and big reference current also can be called as second reference current.
In one embodiment, described output driver module 120 includes N, be respectively the first output driver module 121, the second output driver module 122 ... with N output driver module 123, described output module 130 also comprises N, be respectively first output module 131, second output module 132 ... with N output module 133, wherein each output driver module is used for driving a corresponding output module, and corresponding output driver module and output module form a current output channels.Therefore, we can say that also described led drive circuit 100 includes N current output channels.
Each output module provides accurate output current by the output terminal OUT of correspondence, and wherein said output current is based on that described reference current produces.When described led drive circuit 100 was used for driving LED, each output terminal OUT can connect one or more LED.Like this, each current output channels can provide accurate output current to the LED that connects.When first mode of operation, each output driver module starts (enabling) or stops (disable) corresponding output module according to 1 corresponding in the output register 152 bit data, wherein when starting an output module, this output module can provide output current to its output terminal, when stopping this output module, this output module then stops to provide output current to its output terminal.At this moment, the N bit data in the output register 152 is used as the output enable signal of N corresponding output channel respectively.When second mode of operation, each output driver module can be adjusted the output current value that data are adjusted output module according to the electric current in the command register 153.
Fig. 2 is each signal sequence in one embodiment the synoptic diagram of led drive circuit 100 when first mode of operation in the utility model, wherein N=16 in this example.See also shown in Figure 2, when 100 operations of described led drive circuit, in the data of the rising edge sampling input end SDI of clock signal clk input, each clock sampling 1 bit data, 16 clock sampling 16 bit data are to shift register 151.Afterwards, described latch enable signal LE is a high level by low transition earlier, through after the about clock period, be low level by the high level saltus step again, this moment, described latch enable signal LE came into force, 16 bit data in the latch shift register 151, described control circuit 110 is current according to lasting time (such as less than 2 cycles) judgement of the high level of described latch enable signal LE simultaneously is first mode of operation, and exports described N bit data to described output register 152 as the output enable data.After this, when the output enable control signal of input end OE input was effective, each output driver module started or stoped corresponding output module according to 1 corresponding in the output register 152 bit data, such as can start with 1 representative, 0 representative stop.In other embodiments, the time that described control circuit 110 also can continue according to the low level of described latch enable signal LE goes to judge to be first mode of operation or second mode of operation, can certainly judge it is first mode of operation or second mode of operation according to other signals rather than latch enable signal.
When described led drive circuit 100 is applied to driving LED, each output terminal OUT can connect one or more LED, and when an output module started, the LED that connects this output module opened (bright), when this output module stopped, the LED that connects this output module closed (going out).Under first mode of operation, by input end SDI and shift register 151 with preset frequency constantly to 16 output enable data of output register 152 inputs, thereby can control the light on and off that LED that each current output channels connects does not stop.Because the light on and off switching frequency of LED is higher than perception of human eyes, so the light on and off that human eye can not perceive LED switch, and only can perceive the variation of the brightness of LED.At this moment, just can regulate the brightness of LED by the dutycycle of control LED.
Fig. 3 is each signal sequence in one embodiment the synoptic diagram of led drive circuit 100 when second mode of operation in the utility model, wherein N=16 in this example.See also shown in Figure 3, when described led drive circuit 100 moves, data in the rising edge sampling input end SDI of clock signal clk input, each clock sampling 1 bit data, 16 clock sampling 16 bit data are to shift register 151, simultaneously described latch enable signal LE is a high level by low transition earlier, through after about 4 clock period, be low level by the high level saltus step again, this moment, described latch enable signal LE came into force, 16 bit data in the latch shift register 151, described control circuit 110 is current according to lasting time (such as greater than 2 cycles) judgement of the high level of described latch enable signal LE simultaneously is second mode of operation, and exports described 16 bit data to described command register 153 as electric current adjustment data.
Fig. 4 is the order format exemplary plot in one embodiment that 16 digit currents in the utility model are adjusted data.See also shown in Figure 4ly, C, D, E, F four figures are according to be checking data, and A is default, and DA0-DA5 six bit data are current data, can realize 2 of output current
6=64 contrasts are whole, and the 6-9 four figures can support 2 according to being channel address
4=16 current output channels.B selects the position for the electric current adjustment modes, if B is 0, it then is the single channel adjustment modes, this moment, control module 110 enabled the output driver module of its corresponding current output channels according to channel address 6-9, and this output driver module storaging current data DA0-DA5 also adjusts the output current of corresponding output module separately in view of the above.If B is 1, then be unified adjustment modes, this moment, control module 110 enabled the output driver module of all current output channels, each output driver module storaging current data DA0-DA5 and the unified in view of the above output current of adjusting the output module of each passage, and the 6-9 channel address is invalid.Like this, under second mode of operation, just can utilize single channel to adjust function the output current of each current output channels is adjusted separately, utilize the unified function of adjusting that the output current of each current output channels is unified to adjust.
An advantage of the present utility model or characteristics are: described led drive circuit 100 can provide the single channel of the output current of each current output channels to adjust function and/or the unified function of adjusting.Utilize the unified function of adjusting that the output current of each current output channels is unified to adjust, can reduce the output current difference that exists between drive circuit chip greatly, can increase substantially the brightness of LED of the LED product (such as light-emitting diode display) that has adopted the led drive circuit in the utility model and the consistance or the homogeneity of colourity like this, simultaneously also can reduce or eliminate the output current difference between the drive circuit chip that the inconsistency owing to outer meeting resistance causes, thereby can reduce conforming requirement outer meeting resistance.Utilizing single channel to adjust function adjusts separately the output current of each current output channels, can reduce even eliminate the output current difference that each interchannel exists greatly, can further improve the brightness of LED of the LED product (such as light-emitting diode display) that has adopted the led drive circuit in the utility model and the consistance or the homogeneity of colourity like this, simultaneously can also reduce or eliminate the brightness that the inconsistency of the optical characteristics (such as luminous flux) owing to LED causes and the inconsistency of colourity, thereby can reduce the consistance requirement of optical characteristics (such as luminous flux), and then reduce the cost of LED LED.
In one embodiment, if 1 LED of each channels drive, the inconsistency of the optical characteristics (such as luminous flux) of 16 LED that led drive circuit 100 drives is higher, that is to say, these 16 LED use same output current to drive, and their brightness and colourity also difference are bigger.In debug process to the LED product, led drive circuit 100 can be switched to second mode of operation, eliminate the inconsistency of the optical characteristics of 16 LED by the output current of independent each current output channels of fine setting, make brightness and the colourity of these 16 LED keep higher consistance at last, yet the output current of each current output channels have than big-difference at this moment.Because the single channel of led drive circuit is adjusted function, thereby can greatly reduce the coherence request of optical characteristics (such as luminous flux) to LED, and the highest part of cost is exactly LED in LED product, makes the LED product that adopts the led drive circuit in the utility model when guaranteeing application quality cost be reduced significantly like this.
Usually, for the brightness of the LED that guarantees to drive and the consistance of colourity, need the difference value of output current of each current output channels of led drive circuit the smaller the better.Yet, single channel in the led drive circuit in the utility model is adjusted function, then broken this thinking set traditionally, the target that its single channel is adjusted function can not be with the output current of each current output channels adjust more consistent, and can be the brightness of LED that each current output channels is driven and colourity adjust more consistent, this adjustment may be with the bigger inconsistency with the optical characteristics that remedies LED of the difference value adjustment of the output current of each current output channels.
In other embodiments, N also can be 4,8,32 or other numeral, current data under same second mode of operation also can change 4,5,7,8,9 or other digit order number into by 6, single channel also can only be set under second mode of operation adjust function or the unified function of adjusting, can also change the figure place of checking data arbitrarily.
Fig. 5 also can be referred to as output circuit for the output module 500(in the utility model) in one embodiment circuit diagram, still being 6 with the current data in the electric current adjustment data in this embodiment is that example is introduced, and described output module 500 can be as the output module in each current output channels of led drive circuit.Described output module 500 includes current drives pipe M1-M6, efferent duct M7 and reference current determining unit 510.
Described reference current determining unit 510 has control end and offset side, and its control signal according to control end is selected in first reference current and second reference current, and produces a bias voltage according to selected reference current and exported by described offset side.The control signal of described control end can be for 1 in the 6 digit current data, such as most significant digit.When concrete the application, most significant digit is 1, then shows selected second reference current, and described bias voltage produces according to second reference current, and most significant digit is 0, then shows selected first reference current, and described bias voltage produces according to first reference current.
The source electrode of each among the current drives pipe M1-M6 is connected to each other and ground connection, and drain electrode all is connected to each other.The grid of current drives pipe M1 directly links to each other with described offset side, and the grid of current drives pipe M2-M6 all links to each other with described offset side by an on-off circuit.Bias voltage on the described offset side drives each current drives pipe M1-M6 makes it produce output current, and drive the current ratio that ratio that each current drives pipe M1-M6 output current that produces and the bias voltage that produces according to second reference current drive the output current that corresponding current driving tube M1-M6 produces equals first reference current and second reference current according to the bias voltage that first reference current produces, be 1:M.
The ratio of the breadth length ratio of current drives pipe M1-M6 is respectively X:1:2:4:8:16, and the current ratio that flows through current drives pipe M1-M6 like this is respectively X:1:2:4:8:16 equally.The control end of the on-off circuit of current drives pipe M2-M6 correspondence links to each other with the output driver module, described output driver module is according to the turn-on and turn-off of other 5 each on-off circuits of control in the 6 digit current data, thereby control the turn-on and turn-off of each current drives pipe, and then realization is whole to 32 contrasts of the output current of output module 500.In addition, unite most significant digit in the 6 digit current data, thereby can be implemented in 64 contrasts of the output current of output module 500 whole the adjustment of reference current.The output current value of current drives pipe M2 is every rank electric current adjusting ranges.
For fear of the big jump of appearance between the maximum output current of the minimum output current of the output module 500 when the big reference current output module 500 during with little reference current, the relative breadth length ratio X of the current drives pipe M1 that grid connects with described offset side all the time needs well-designed, as a general design consideration can allow X satisfy X+1+2+4+8+16 less than M*X and X+1+2+4+8+16 near M*X.For instance, if M=4, X can be 11 so, if M=2, X can be 32 so, if M=3, X can be 16 so.Every rank electric current adjusting range when in one embodiment, X+1+2+4+8+16 is meant that near M*X between the two difference is less than or equal to big reference current.
When led drive circuit is second mode of operation, the output driver module in can memory command register 153 6 digit current data and control the conducting of current drives pipe M2-M6 of output module 500 or the selection of shutoff and reference current in view of the above.Can store 6 digit current data of acquiescence in each output driver module in advance,, in output current adjustment process subsequently, can it be covered with 6 up-to-date digit current data such as being 101010.Enumerate some adjust output current according to current data example below, if 6 digit current data are 011100, because most significant digit is 0, then selected first reference current, the decimal number that the back is 5 is 28, then can be with current drives pipe M4-M6 conducting, if 6 digit current data are 011110, because most significant digit is 0, then selected first reference current, the decimal number that the back is 5 is 30, then can be with current drives pipe M3-M6 conducting, if 6 digit current data are 101011, because most significant digit is 1, then selected second reference current, back 5 decimal number is 11, then can be with current drives pipe M2, M3 and M5 conducting.When specific implementation, can be with the on-off circuit of each the respectively corresponding current drives pipe in back 5, last corresponding current driving tube M2 wherein, penultimate corresponding current driving tube M3, by that analogy, the 5th corresponding current driving tube M6.
The drain electrode of described efferent duct M7 links to each other with output terminal OUT, and source electrode links to each other with the drain electrode of current drives pipe M1-M6.The grid of described efferent duct M7 links to each other with the output driver module as the switch control end of described efferent duct M7.When first mode of operation, the output driver module can be controlled conducting or the shutoff of efferent duct M7 according to 1 of the correspondence of the output enable data in the output register 152, thereby control the starting or stoping of output module 500 exported driver module this moment and controlled the conducting of current drives pipe M2-M6 of output module 500 or the selection of shutoff and reference current according to being stored in current data in it.
Fig. 6 is the 6 digit current data of the output module 500 among Fig. 5 and the curve synoptic diagram of current gain, and wherein said current gain is actual output current value and the ratio of giving tacit consent to output current value, and this moment, described acquiescence output current value was 101010, M=4.Usually, the default value of the output module of each current output channels of each led drive circuit is consistent, when Using Defaults the consistance of the brightness that can not guarantee external LED and colourity, the output current that can enter under second mode of operation the output module of each current output channels of each led drive circuit carries out separately or unified fine setting.Curve among the figure is formed by two different straight line L1 and L2 linkings of slope, adopt little reference current to carry out the electric current adjustment in the process of straight line L1 always, every rank electric current adjusting range is less, adopt big reference current to carry out the electric current adjustment in the process of straight line L2 always, every rank electric current adjusting range is bigger, and the M of every rank electric current adjusting range doubly during for L1.Such design also is to consider following several aspect: 1, when same exponent number is adjusted, can obtain wider setting range; 2, hour at output current, because human eye is more responsive to the variation of the optical characteristics (such as luminous flux) of LED, therefore adopt adjustment more by a small margin, when electric current is big, because human eye to the variation relative insensitivity of the optical characteristics (such as luminous flux) of LED, therefore adopts adjustment by a relatively large margin.
In one embodiment, described current drives pipe M1-M6 and efferent duct M7 are nmos pass transistor.Described efferent duct M7 is a high-voltage tube.
In other embodiments, the figure place that electric current is adjusted the current data in the data can also be 5,7 or other figure place, wherein selects the position as reference current for 1, and is remaining as current drives pipe control bit.For instance, figure place in current data is 5 o'clock, 4 as current drives pipe control bit, can remove the current drives pipe M6 of the output module among Fig. 5 just passable this moment, also need to reset the relative breadth length ratio X of current drives pipe M1 this moment, make it satisfy X+1+2+4+8 and get final product near M*X less than M*X and X+1+2+4+8, can realize 2 of output current this moment
5Contrast is whole.Again for instance, figure place in current data is 7 o'clock, 6 as current drives pipe control bit, increase that similar current drives pipe M8 is set is just passable with current drives pipe M6 this moment in can the output module in Fig. 5, the drain electrode of current drives pipe M8 links to each other with the drain electrode of current drives pipe M1-M6, source electrode links to each other with the source electrode of current drives pipe M1-M6, grid links to each other with described offset side by on-off circuit, current drives pipe M8 is 32:1 with the ratio of the breadth length ratio of current drives pipe M2, equally also need to reset the relative breadth length ratio X of current drives pipe M1 this moment, and it satisfies X+1+2+4+8+16+32 and gets final product near M*X less than M*X and X+1+2+4+8+16+32.
In general, the ratio of the breadth length ratio of current drives pipe M2-M6 satisfies: 2
0: 2
1: 2
2: 2
3: 2
4In one embodiment, if the number of the current drives pipe that grid is connected with offset side by on-off circuit is Y, the ratio of the breadth length ratio of the current drives pipe that is connected with offset side by on-off circuit of the current drives pipe that directly is connected with described offset side of grid and each grid is respectively so: X:2
0: 2
1: ...: 2
Y-2: 2
Y-1, wherein the relative breadth length ratio X of the current drives pipe of the direct and described offset side connection of grid satisfies: X+2
0+ 2
1+ ... + 2
Y-2+ 2
Y-1Less than M*X and X+2
0+ 2
1+ ... + 2
Y-2+ 2
Y-1And the every rank electric current adjusting range the when difference between the M*X is less than or equal to second reference current.
Another characteristics of the present utility model or advantage are: for output module provides two kinds of reference currents that vary in size, and when the minimum output current of output module is greater than little reference current during big reference current output module maximum output current and every rank electric current adjusting range of output module when the difference between the maximum output current of output module is less than or equal to big reference current when the minimum output current of output module and little reference current during big reference current, expand the setting range of output current like this, and more met human eye brightness law of perception.
Another characteristics of the present utility model or advantage are: the ratio of the breadth length ratio of each in check Y current drives pipe is respectively: 2
0: 2
1: ...: 2
Y-2: 2
Y-1Thereby, utilize minimum driving tube to realize 2 of output current
Y+1Contrast is whole, and preceding 2
YThe electric current adjusting range on rank is uniform substantially, back 2
YThe electric current adjusting range on rank is uniform substantially, and preceding 2
YThe electric current adjusting range on rank and back 2
YThe ratio of the electric current adjusting range on rank is the current ratio of big or small reference current, is 1:M.
In another embodiment, each current output channels of the led drive circuit in the utility model can drive a plurality of LED, and such as 4, this moment, each current output channels can adopt time-multiplexed mode that a plurality of LED that connect are thereon driven.At this moment, the output driver module can be provided with the current data memory block to store the current data of each LED for each LED, when second mode of operation, can carry out the electric current adjustment to each LED of each current channel, and the current data that adjustment can be finished is stored in the output driver module, can adjust the brightness of the different LED under the same current output channels like this, with the inconsistency of the optical characteristics that remedies these LED.
When concrete the application, the led drive circuit 100 that proposes in the utility model is particularly suitable for the driving LED display, and described light-emitting diode display comprises the led array of being made up of some LED.If each current output channels of each led drive circuit 100 can drive 4 LED, each led drive circuit can drive 64 LED like this, and a light-emitting diode display may need tens, up to a hundred or more led drive circuit 100.Each current output channels of different LED driving circuit unified adjusted function can improve the brightness between the LED of different LED driving circuit correspondence and the inconsistency of colourity, and the single channel of each current output channels of same led drive circuit is adjusted function then can improve the brightness between the LED of this led drive circuit correspondence and the inconsistency of colourity.Because the electric current of led drive circuit is adjusted function, especially single channel is adjusted function, the feasible conforming requirement that can relax the optical characteristics of LED, but can guarantee that equally light-emitting diode display has high-quality image display effect.
Above the utility model has been carried out the enough detailed description with certain singularity.Under those of ordinary skill in the field should be appreciated that the description among the embodiment only is exemplary, under the prerequisite that does not depart from true spirit of the present utility model and scope, make change and all should belong to protection domain of the present utility model.The utility model scope required for protection is limited by described claims, rather than limit by the foregoing description among the embodiment.
Claims (10)
1. output circuit, it is characterized in that: it comprises:
Reference current determining unit with control end and offset side, its control signal according to control end is selected one between first reference current and second reference current, and produce a bias voltage according to selected reference current and export by described offset side, wherein first reference current is less than second reference current;
Some current drives pipes, its source electrode is connected to each other, its drain electrode is connected to each other, the grid of one of them current drives pipe directly links to each other with described offset side, the grid of all the other each current drives pipes links to each other with described offset side by an on-off circuit, controls the turn-on and turn-off of corresponding current driving tube by the turn-on and turn-off of controlling each on-off circuit; With
Efferent duct, its source electrode links to each other with the drain electrode of described current drives pipe, and its drain electrode is as the output terminal of output circuit, and its grid is controlled the turn-on and turn-off of described efferent duct.
2. output circuit according to claim 1 is characterized in that, the current ratio of first reference current and second reference current is 1: M, wherein 1.5≤M≤4.5.
3. output circuit according to claim 2, it is characterized in that, bias voltage on the described offset side drives each current drives pipe makes it produce output current, and drives the current ratio that ratio that each current drives pipe output current that produces and the bias voltage that produces according to second reference current drive the output current that the corresponding current driving tube produces equals first reference current and second reference current according to the bias voltage that first reference current produces.
4. output circuit according to claim 2 is characterized in that, the ratio of the breadth length ratio of each current drives pipe that grid links to each other with described offset side by on-off circuit is respectively: 2
0: 2
1: ...: 2
Y-2: 2
Y-1, the number of the Y current drives pipe that to be grid link to each other with described offset side by on-off circuit wherein, described output circuit supports 2
Y+1The output current adjustment on rank.
5. output circuit according to claim 4 is characterized in that, the relative breadth length ratio X of the current drives pipe that the direct and described offset side of grid connects satisfies: X+2
0+ 2
1+ ...+2
Y-2+ 2
Y-1Less than M*X and X+2
0+ 2
1+ ...+2
Y-2+ 2
Y-1And the every rank electric current adjusting range the when difference between the M*X is less than or equal to second reference current.
6. output circuit according to claim 5, it is characterized in that, according to Y+1 digit current data described output circuit is carried out the output current adjustment, wherein, control the turn-on and turn-off of each on-off circuit according to all the other the Y positions in the current data according to 1 in the current data control signal of determining the control end of described reference current determining unit.
7. led drive circuit, it is characterized in that: it comprises:
Control module receives the latch enable signal that the latch enable input end is imported, and judges that according to described latch enable signal current is first mode of operation or second mode of operation;
Registers group receives the N bit data that data input pin is imported;
N output driver module and N corresponding output circuit, each output driver module drives corresponding output circuit, and each output circuit provides output current by the output terminal of correspondence,
When first mode of operation, each output driver module starts or stops corresponding output circuit according to 1 bit data of the correspondence in the N bit data in the registers group, when second mode of operation, described N bit data includes the adjustment modes data, current data and channel address data, when the adjustment modes data are adjusted for unification, each output driver module is according to the unified output current of adjusting each output circuit of described current data, when the adjustment modes data are the single channel adjustment, output driver module according to described channel address data enable correspondence, the output driver module that this enables is adjusted the output current of corresponding output circuit separately according to described current data, N is a natural number
Each output circuit is the arbitrary described output circuit of claim 1-5.
8. led drive circuit according to claim 7 is characterized in that, N is 4,8,16 or 32.
9. led drive circuit according to claim 7 is characterized in that,
It also comprises: the reference current module, and it provides first reference current and second reference current, and wherein first reference current is less than second reference current,
Each output driver module starts or stops corresponding output circuit according to 1 bit data of the correspondence in the N bit data in the registers group and is: each output driving circuit is according to the turn-on and turn-off of the efferent duct of the corresponding output circuit of 1 bit data of the correspondence in the N bit data in registers group control;
Each output driver module according to the unified output current of adjusting each output circuit of described current data is: each output driver module sends control signal according to 1 in the described current data control end to the reference current determining unit of correspondence, described reference current determining unit is selected one according to described control signal between first reference current and second reference current, each output driver module is controlled the turn-on and turn-off of each on-off circuit in the corresponding output circuit according to the remaining bit in the described current data;
The output current that the output driver module that this enables is adjusted corresponding output circuit separately according to described current data is: the output driver module that this enables sends control signal according to 1 control end to described reference current determining unit in the described current data, described reference current determining unit is selected one according to described control signal between first reference current and second reference current, the output driver module that this enables is controlled the turn-on and turn-off of each on-off circuit in the corresponding output circuit according to the remaining bit in the described current data.
10. led drive circuit according to claim 8, it is characterized in that, registers group includes N bit shift register, N position output register and N order of the bit register, described shift register receives the serial data of data input pin input, after described latch enable signal comes into force, N bit data in the latch shift register, and current when being first mode of operation, export described N bit data to described output register, when being second mode of operation, export described N bit data to described command register current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205350475U CN201927327U (en) | 2010-09-19 | 2010-09-19 | LED driving circuit and output circuit thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205350475U CN201927327U (en) | 2010-09-19 | 2010-09-19 | LED driving circuit and output circuit thereof |
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| Publication Number | Publication Date |
|---|---|
| CN201927327U true CN201927327U (en) | 2011-08-10 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010205350475U Expired - Lifetime CN201927327U (en) | 2010-09-19 | 2010-09-19 | LED driving circuit and output circuit thereof |
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|---|---|
| CN (1) | CN201927327U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101937650A (en) * | 2010-09-19 | 2011-01-05 | 无锡力芯微电子股份有限公司 | LED display, LED drive circuit and output circuit thereof |
| CN103582221A (en) * | 2012-07-23 | 2014-02-12 | 明阳半导体股份有限公司 | light emitting diode driving circuit, driving system and driving method thereof |
| CN109584789A (en) * | 2019-01-30 | 2019-04-05 | 上海艾为电子技术股份有限公司 | A kind of LED drive circuit and illuminating circuit |
| CN114690827A (en) * | 2022-04-14 | 2022-07-01 | 无锡力芯微电子股份有限公司 | Bias circuit for inhibiting reference voltage from second stable state |
-
2010
- 2010-09-19 CN CN2010205350475U patent/CN201927327U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101937650A (en) * | 2010-09-19 | 2011-01-05 | 无锡力芯微电子股份有限公司 | LED display, LED drive circuit and output circuit thereof |
| CN101937650B (en) * | 2010-09-19 | 2012-11-21 | 无锡力芯微电子股份有限公司 | LED display, LED drive circuit and output circuit thereof |
| CN103582221A (en) * | 2012-07-23 | 2014-02-12 | 明阳半导体股份有限公司 | light emitting diode driving circuit, driving system and driving method thereof |
| CN109584789A (en) * | 2019-01-30 | 2019-04-05 | 上海艾为电子技术股份有限公司 | A kind of LED drive circuit and illuminating circuit |
| CN114690827A (en) * | 2022-04-14 | 2022-07-01 | 无锡力芯微电子股份有限公司 | Bias circuit for inhibiting reference voltage from second stable state |
| CN114690827B (en) * | 2022-04-14 | 2024-02-06 | 无锡力芯微电子股份有限公司 | Bias circuit for inhibiting reference voltage second steady state |
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