CN105208730A - LED drive circuit capable of achieving current matching - Google Patents
LED drive circuit capable of achieving current matching Download PDFInfo
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- CN105208730A CN105208730A CN201510629832.4A CN201510629832A CN105208730A CN 105208730 A CN105208730 A CN 105208730A CN 201510629832 A CN201510629832 A CN 201510629832A CN 105208730 A CN105208730 A CN 105208730A
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Abstract
The invention provides an LED drive circuit capable of achieving current matching. The LED drive circuit comprises a reference current source, a first resistor and multiple LED drive branch circuits; the first connecting end of the first resistor is connected with the output end of the reference current source, and the second connecting end of the first resistor is connected with the grounded end; each LED drive branch circuit comprises a programmable operational amplifier, an output transistor, a drive resistor and an offset calibration circuit, wherein the first connecting end of the output transistor serves as the output end of the LED drive branch circuit and can be connected with a driven LED, the first input end of the offset calibration circuit is connected with the first connecting end of the first resistor, the second input end of the offset calibration circuit is connected with the second input end of the programmable operational amplifier, and the first resistor are mutually matched with matching resistors to reduce relative errors between the first resistor and the matching resistor. By means of the characteristic that the relative errors of the matching resistors are small, more consistent LED drive currents can be supplied.
Description
[technical field]
The present invention relates to LED (light-emittingdiode) drive circuit chip design field, particularly a kind of LED drive circuit of currents match.
[background technology]
Multipath LED drive circuit is widely used in big screen LED display, the panel computer of such as large-screen, notebook computer, TV or large-screen billboard.In these display devices, all provide backlight by LED.Because LED array is very large, needs LED multi-path to drive, in order to ensure the uniformity of large scale display, needing the drive current of every paths of LEDs all as far as possible equal.
Fig. 1 describes a kind of multipath LED drive circuit of prior art, which describes the situation that two string LED export.In Fig. 1, the drain electrode of transistor MN3 is adjusted to 0.3V by operational amplifier OP1, and the grid voltage of transistor MN41, MN42 and MN3 is equal, and (ensured by operational amplifier OP2, voltage GT adjustment is equaled the grid voltage GN3 of transistor MN3 by OP2.Operational amplifier OP31 adjustment simultaneously makes the drain voltage DN41 of transistor MN41 equal voltage VD, and operational amplifier OP32 adjustment makes the drain voltage DN42 of transistor MN42 also equal voltage VD.Therefore the grid voltage of transistor MN41, MN42 all equals the grid voltage of transistor MN3, and the drain voltage of transistor MN41, MN42 also all equals the drain voltage of transistor MN3, and source electrode all ground connection of transistor MN41, MN42, MN3, voltage is also equal.The drain current of such MN41, MN42 is proportional to the drain current of MN3, and its ratio is the ratio of the breadth length ratio of the relative MN3 of MN41, MN42.The width of general design MN41 with MN42 is all identical with length, so the electric current of MN41 and MN42 should be equal.But actual conditions, due to process deviation, between chip, MN41 drain current and MN42 drain current consistency are not so desirable, and possible deviation is between-5% to+5%.Reduce this deviation, be conducive to improving large-size screen monitors display effect.First there is input deviation in operational amplifier OP31 and OP32, namely there is certain little value deviation between its positive-negative input end voltage.Fig. 1 design is by allowing MN3, MN41 and MN42 all be operated in saturation region, contribute to reducing the impact of this deviation on current mismatch, even so, the input deviation of operational amplifier OP31 and OP31 still can cause the drain current mismatch of MN41 and MN42 to a certain extent.In addition, also there is the mismatch of device itself between MN41 and MN42, such as its threshold voltage may there are differences, and its gate oxide thickness may there are differences, and there are differences between the developed width of raceway groove and length.There is input mismatch in operational amplifier OP2 in addition, causes there are differences between the grid voltage of MN41, MN42 and the grid voltage of MN3, the drain current ratio of the drain current of transistor MN41, MN42 and transistor MN3 can be caused like this to there is chip chamber deviation.
Therefore, a kind of LED drive circuit of currents match of improvement is urgently proposed.
[summary of the invention]
An object of the present invention is the LED drive circuit of the currents match providing a kind of improvement, and it can drive LED multi-path, and keeps the drive current of each paths of LEDs to have higher consistency.
In order to solve the problem, the invention provides a kind of LED drive circuit, it comprises: reference current source, first resistance, its first link is connected with the output of described reference current source, and its second link is connected with earth terminal, multiple LED drives branch road, each LED drives branch road to comprise programmable operational amplifier, output transistor, drive resistance and mistuning calibration function circuit, the first input end of wherein said programmable operational amplifier and the first link of the first resistance, its second input is connected with driving the first link of resistance, first link of described driving resistance is also connected with the second link of output transistor, second link of described driving resistance is connected with earth terminal, the output of described programmable operational amplifier is connected with the control end of described output transistor, first link of described output transistor drives the output of branch road can be connected with driven LED as this LED, the first input end of described mistuning calibration function circuit and the first link of the first resistance, second input of described mistuning calibration function circuit is connected with the second input of described programmable operational amplifier, described mistuning calibration function circuit output bias calibrating signal gives described programmable operational amplifier, described programmable operational amplifier is calibrated based on described deviation calibration signal, wherein the first resistance and described build-out resistor are mated mutually with most reduction relative error each other.
Further, the relative error of the first resistance and described build-out resistor is less than or equal to +/-0.1%.
Further, described output transistor is nmos pass transistor, and the source electrode of described nmos pass transistor is the second link of described output transistor, and the drain electrode of described nmos pass transistor is the first link of described output transistor.
Further, negative electrode and the described LED of described driven LED drive the output of branch road to be connected, and its anode is connected with power voltage terminal.
Further, one of them LED drives the first input end of the mistuning calibration function circuit in branch road also can be connected to the first link of the driving resistance in another LED driving branch road.
Further, described mistuning calibration function circuit the first input end of described mistuning calibration function circuit voltage higher than the voltage of the second input and the first predetermined threshold and time, adjust its deviation calibration signal, described mistuning calibration function circuit is when the voltage of the first input end of described mistuning calibration function circuit is lower than the voltage of the second input and the second predetermined threshold poor, adjust its deviation calibration signal, the first input end of described mistuning calibration function circuit voltage lower than the voltage of the second input and the first predetermined threshold and and higher than the voltage of the second input and the second predetermined threshold poor time, keep its deviation calibration signal.
Further, described mistuning calibration function circuit comprises the first voltage comparator circuit, the second voltage comparator circuit and logical output circuit, first voltage comparator circuit the first input end of described mistuning calibration function circuit voltage higher than the voltage of the second input and the first predetermined threshold and time, it exports the first signal, otherwise exports secondary signal; Second voltage comparator circuit is when the voltage of the first input end of described mistuning calibration function circuit is lower than the voltage of the second input and the second predetermined threshold poor, and it exports the first signal, otherwise exports secondary signal; Described logical output circuit is when the first voltage comparator circuit exports the first signal and the second voltage comparator circuit exports secondary signal, increase its deviation calibration signal, when the first voltage comparator circuit exports secondary signal and the second voltage comparator circuit exports the first signal, reduce its deviation calibration signal, when the first voltage comparator circuit exports secondary signal and the second voltage comparator circuit exports secondary signal, keep its deviation calibration signal.
Further, described programmable operational amplifier comprises: the first difference transistor and the second difference transistor, wherein the first difference transistor or the second difference transistor include the differential crystal pipe unit of multiple parallel connection, each in Partial Differential transistor unit is connected with a programmable switch, the control end of described programmable switch receives described deviation calibration signal, under the control of described deviation calibration signal, described programmable switch conducting or cut-off.
Further, described programmable operational amplifier comprises the multiple output resistances being positioned at the series connection exported on branch road, first link of each output resistance is connected with the output of described programmable operational amplifier by a programmable switch, the control end of described programmable switch receives described deviation calibration signal, under the control of described deviation calibration signal, described programmable switch conducting or cut-off.
Compared with prior art, the present invention, by arranging the resistance of coupling mutually, utilizes the feature that the resistance relative error of coupling is less, provides more consistent LED drive current.In addition, the input offset voltage of operational amplifier by mistuning calibration function circuit calibrates to very little, thus can further improve the consistency of each paths of LEDs drive current.
[accompanying drawing explanation]
In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.Wherein:
Fig. 1 illustrates the examples of circuits figure of LED drive circuit of the prior art;
Fig. 2 illustrates the LED drive circuit examples of circuits figure in one embodiment in the present invention;
Fig. 3 illustrates the mistuning calibration function circuit examples of circuits figure in one embodiment in Fig. 2;
Fig. 4 illustrates the programmable operational amplifier examples of circuits figure in one embodiment in Fig. 2;
Fig. 5 illustrates the programmable operational amplifier examples of circuits figure in another embodiment in Fig. 2;
Fig. 6 illustrates the logical output circuit examples of circuits figure in one embodiment in Fig. 3;
Fig. 7 illustrates the LED drive circuit examples of circuits figure in another embodiment in the present invention.
[embodiment]
For enabling above-mentioned purpose of the present invention, feature and advantage become apparent more, and below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
The invention provides the multipath LED drive circuit of the currents match of improvement, it can drive LED multi-path, and the consistency of the drive current of each paths of LEDs is higher.
Fig. 2 illustrates the LED drive circuit 200 examples of circuits figure in one embodiment in the present invention.As shown in Figure 2, described LED drive circuit 200 comprises reference current source I21, the first resistance R1 and multiple LED driving branch road.Having illustrated in Fig. 2 that two LED drive branch roads, be designated as 210,220 respectively, in other embodiments, also can be three tunnels, four tunnels or more multichannel.Each LED drives branch road to drive a paths of LEDs, and negative electrode and the LED of driven LED drive the output of branch road to be connected, and the anode of driven LED is connected with power voltage terminal VCC.Concrete, negative electrode and the LED of LED1 drive the output of branch road 210 to be connected, and negative electrode and the LED of LED2 drive the output of branch road 220 to be connected, and the anode of LED1 is connected with power voltage terminal VCC with the anode of LED2.First link of the first resistance R1 is connected with the output of described reference current source I21, and its second link is connected with earth terminal.
As shown in Figure 2, each driving branch road comprises programmable operational amplifier, output transistor, driving resistance and mistuning calibration function circuit.The first input end of wherein said programmable operational amplifier and first link of the first resistance R1, its second input is connected with driving the first link of resistance, first link of described driving resistance is also connected with the second link of output transistor, second link of described driving resistance is connected with earth terminal, the output of described programmable operational amplifier is connected with the control end of described output transistor, the first input end VP of described mistuning calibration function circuit is connected with the first input end of described programmable operational amplifier, second input VN of described mistuning calibration function circuit is connected with the second input of described programmable operational amplifier, described mistuning calibration function circuit output bias calibrating signal D0-Dn-1 gives described programmable operational amplifier, described programmable operational amplifier is calibrated based on described deviation calibration signal.
First resistance R1 and described build-out resistor mate to reduce relative error each other as far as possible mutually.
Concrete, programmable operational amplifier in described driving branch road 210 is OP21, output transistor in described driving branch road 210 is nmos pass transistor MN21, and the driving resistance in described driving branch road 210 is R2, and the mistuning calibration function circuit in described driving branch road 210 is the first mistuning calibration function circuit; Programmable operational amplifier in described driving branch road 220 is OP22, output transistor in described driving branch road 220 is nmos pass transistor MN22, driving resistance in described driving branch road 220 is R3, and the mistuning calibration function circuit in described driving branch road 220 is the second mistuning calibration function circuit.Programmable operational amplifier is the first input end of OP21, OP22 is normal phase input end, and the second input is negative-phase input.The source electrode of nmos pass transistor MN21 and MN22 is the second link of output transistor, and the drain electrode of nmos pass transistor MN21 and MN22 is the first link of output transistor, and the grid of nmos pass transistor MN21 and MN22 is the control end of output transistor.
In the present invention, by selecting type identical, through meticulous matched design, the first resistance R1 and the relative error between build-out resistor R2 and R3 can be designed into the precision of 0.1%.In the present invention, resistance R1, R2, R3 will through meticulous matched design, and its relative scale is very accurate.Industry such as can be adopted to know various technology, and design as Central Symmetry and keep the sense of current of each section of resistance all identical, the width of each section of resistance all designs identical with length.
In the present invention, reference current source I21 provides reference current I21, and reference current I21 flows through resistance R1 and produces reference voltage VD.Operational amplifier OP21 and OP22 adjustment makes the voltage of node SN51 and SN52 equal voltage VD.Operational amplifier OP21 with OP22 in the present invention is different from conventional operational amplifiers, is its input deviation programmable operational amplifier.By the biased poor calibrating signal D0 ~ Dn-1 of n, the input deviation voltage (or claiming input offset voltage) of operational amplifier can be changed.The input deviation of operational amplifier OP21 and OP22 all by the mistuning calibration function circuit calibrates of correspondence to small value, such as, within 1mV.Can ensure that the voltage deviation of node VD voltage and node SN51, SN52 is very little after calibration, can be approximated to be and think equal.The input deviation up to 30mV may be there is in unregulated normal operation amplifier.Design deviation calibrating signal figure place is more, can realize higher calibration accuracy.According to kirchhoff KCL law, the electric current of LED1 equals resistance R2 electric current, and the electric current of LED2 equals the electric current of resistance R3.According to above-mentioned principle, the electric current of R2 equals I21.R1/R2, and the electric current of R3 equals I21.R1/R3.When R2 equals R3, the electric current of LED1 and LED2 is equal.Due to R1 and R2, and R1 and R3 have employed the design of coupling mutually, and their relative error is very little, and the error between the electric current therefore on R2 and R3 is also very little.It is to be understood that in integrated circuits the matching of resistance far above the matching of transistor.
As shown in Figure 2, described mistuning calibration function circuit the first input end of described mistuning calibration function circuit voltage VP higher than the voltage VN of the second input and the first predetermined threshold (can be zero) and time, increase its deviation calibration signal D0-Dn-1, described mistuning calibration function circuit, when the voltage VP of the first input end of described mistuning calibration function circuit is lower than the voltage VN of the second input and the second predetermined threshold poor, reduces its deviation calibration signal D0-Dn-1.The first input end of described mistuning calibration function circuit voltage lower than the voltage of the second input and the first predetermined threshold and and higher than the voltage of the second input and the second predetermined threshold poor time, keep its deviation calibration signal D0-Dn-1.
As shown in Figure 3, described mistuning calibration function circuit comprises the first voltage comparator circuit 310, second voltage comparator circuit 320 and logical output circuit 330.First voltage comparator circuit 310 the first input end VP of described mistuning calibration function circuit voltage higher than the voltage of the second input and the first predetermined threshold and time, it exports the first signal, otherwise exports secondary signal; Now the first predetermined threshold is 0.Second voltage comparator circuit 320 is when the voltage of the first input end of described mistuning calibration function circuit is lower than the voltage of the second input and the second predetermined threshold poor, and it exports the first signal, otherwise exports secondary signal, and now the second predetermined threshold is voltage Ve.Described logical output circuit 330 is when the first voltage comparator circuit 310 exports the first signal and the second voltage comparator circuit 320 exports secondary signal, increase its deviation calibration signal, when the first voltage comparator circuit 310 exports secondary signal and the second voltage comparator circuit 320 exports the first signal, reduce its deviation calibration signal, when the first voltage comparator circuit 310 exports secondary signal and the second voltage comparator circuit 320 exports secondary signal, keep its deviation calibration signal.
Concrete, the first voltage comparator circuit 310 comprises switch S 12, S11, S13, inverter INV11, inverter INV13, inverter INV14, operational amplifier OP5, d type flip flop ffdf1 and electric capacity C11.Wherein first input end VP is connected through the normal phase input end of switch S 12 with operational amplifier OP5, and the second input VN is connected through the normal phase input end of switch S 11 with operational amplifier OP5.The negative-phase input of operational amplifier OP5 is connected with earth terminal by electric capacity C11, and negative-phase input is also connected with its output by switch S 13.Clock signal C K1 is connected with the control end of switch S 11, and is connected with the control end of switch S 12 by inverter INV11.Inverter INV13, inverter INV14 are series between the input of operational amplifier OP5 and the input d of d type flip flop ffdf1 successively, and the clock end of d type flip flop ffdf1 is connected with clock signal C K4.The output q of d type flip flop ffdf1 outputs signal VH.Be the first signal at the high level of signal VH, low level is secondary signal.
Concrete, the second voltage comparator circuit 320 comprises switch S 22, S21, S23, inverter INV21, inverter INV23, inverter INV24, operational amplifier OP4, d type flip flop ffdf2 and electric capacity C21.Wherein first input end VP is connected with the normal phase input end of operational amplifier OP4 through switch S 22, voltage source V e, and the second input VN is connected through the normal phase input end of switch S 21 with operational amplifier OP4.The negative-phase input of operational amplifier OP4 is connected with earth terminal by electric capacity C21, and negative-phase input is also connected with its output by switch S 23.Clock signal C K1 is connected with the control end of switch S 21, and is connected with the control end of switch S 22 by inverter INV21.Inverter INV23, inverter INV24 are series between the input of operational amplifier OP4 and the input d of d type flip flop ffdf2 successively, and the clock end of d type flip flop ffdf2 is connected with clock signal C K4.The output q of d type flip flop ffdf2 outputs signal VL.Be the first signal at the high level of signal VL, low level is secondary signal.
Concrete, as shown in Figure 3, when VP voltage is greater than VN voltage, VH becomes high level, and the deviation calibration signal D0-Dn-1 that this logical output circuit exports adds 1; When VP voltage is less than VN-Ve, VL becomes high level, and the deviation calibration signal D0-Dn-1 that this logical output circuit exports subtracts 1.When VP voltage is between VN and VN-Ve, VH and VL is low level, and the deviation calibration signal D0-Dn-1 that this logical output circuit exports remains unchanged.
Fig. 6 illustrates the logical output circuit 330 examples of circuits figure in one embodiment in Fig. 3.As shown in Figure 6, in order to simplified characterization, be just introduced for 2 biased poor calibrating signals herein.In reality, the implementation of more long number can be designed as required.Can realizing by Digital Design mode, such as, by writing verilog or VHDL code, producing required circuit by automated software synthesis.Described logical output circuit 330 comprises or door OR1, OR2, OR3, with door AND1, AND2, AND3, AND4, NOR gate NOR1, inverter INV2, inverter INV3, inverter INV1, d type flip flop ffdf3, ffdf4.Concrete annexation as shown in Figure 6.
Fig. 4 illustrates the programmable operational amplifier examples of circuits figure in one embodiment in Fig. 2.As shown in Figure 4, described programmable operational amplifier comprises the first difference transistor MP7 and the second difference transistor 410, wherein the second difference transistor 410 includes the differential crystal pipe unit MP81 of multiple parallel connection, MP82, MP8n, MP8, Partial Differential transistor unit MP81, MP82, each and a programmable switch MPS1 in MP8n, MPS2, MPSn connects, described programmable switch MPS1, MPS2, the control end of MPSn receives described deviation calibration signal D0-Dn-1, under the control of described deviation calibration signal, described programmable switch MP81, MP82, MP8n conducting or cut-off.As shown in Figure 4, described programmable operational amplifier also comprises current source I1, I2, nmos pass transistor MN1, MN2, MN3.By conducting or end described programmable switch MP81, MP82, MP8n, differential crystal pipe unit MP81, MP82, MP8n can be made to introduce the second difference transistor 410, thus trim the input deviation voltage of this programmable operational amplifier.
Fig. 5 illustrates the programmable operational amplifier examples of circuits figure in another embodiment in Fig. 2.As shown in Figure 5, described programmable operational amplifier comprises the multiple output resistance R5n-R51 being positioned at the series connection exported on branch road, first link of each output resistance R5n-R51 is connected with the output of described programmable operational amplifier by a programmable switch SW1-SWn, the control end of described programmable switch SW1-SWn receives described deviation calibration signal D0-Dn-1, under the control of described deviation calibration signal D0-Dn-1, described programmable switch SW1-SWn conducting or cut-off.By conducting or end described programmable switch SW1-SWn, the input deviation voltage of this programmable operational amplifier can be regulated.As shown in Figure 5, described programmable operational amplifier also comprises current source I51, I52, nmos pass transistor MN1, MN2, MN3, difference transistor MP7 and MP8.
Fig. 7 illustrates the LED drive circuit examples of circuits figure in another embodiment in the present invention.LED drive circuit in Fig. 7 and the difference of the LED drive circuit shown in Fig. 2 are: described LED drive the first input end VP of the second mistuning calibration function circuit in branch road 220 to be connected to the first link that described LED drives the driving resistance R2 in branch road 210, and as shown in Figure 2, described LED drives the first input end VP of the second mistuning calibration function circuit in branch road 220 to be connected to first link of the first resistance R1.Like this, the effect of high matching precision in the present invention can be realized equally.
Connection in the present invention, connect, being connected etc. represents that the word be electrically connected all refers to direct or indirect electric connection, describedly indirectly refers to by an element, the electric connections such as such as electric capacity, inductance or transistor.
It is pointed out that the scope be familiar with person skilled in art and any change that the specific embodiment of the present invention is done all do not departed to claims of the present invention.Correspondingly, the scope of claim of the present invention is also not limited only to previous embodiment.
Claims (9)
1. a LED drive circuit, is characterized in that, it comprises:
Reference current source;
First resistance, its first link is connected with the output of described reference current source, and its second link is connected with earth terminal;
Multiple LED drives branch road, each LED drives branch road to comprise programmable operational amplifier, output transistor, drive resistance and mistuning calibration function circuit, the first input end of wherein said programmable operational amplifier and the first link of the first resistance, its second input is connected with driving the first link of resistance, first link of described driving resistance is also connected with the second link of output transistor, second link of described driving resistance is connected with earth terminal, the output of described programmable operational amplifier is connected with the control end of described output transistor, first link of described output transistor drives the output of branch road can be connected with driven LED as this LED, the first input end of described mistuning calibration function circuit and the first link of the first resistance, second input of described mistuning calibration function circuit is connected with the second input of described programmable operational amplifier, described mistuning calibration function circuit output bias calibrating signal gives described programmable operational amplifier, described programmable operational amplifier is calibrated based on described deviation calibration signal,
Wherein the first resistance and described build-out resistor are mated mutually with most reduction relative error each other.
2. LED drive circuit according to claim 1, is characterized in that, the relative error of the first resistance and described build-out resistor is less than or equal to +/-0.1%.
3. LED drive circuit according to claim 1, it is characterized in that, described output transistor is nmos pass transistor, and the source electrode of described nmos pass transistor is the second link of described output transistor, and the drain electrode of described nmos pass transistor is the first link of described output transistor.
4. LED drive circuit according to claim 1, is characterized in that, negative electrode and the described LED of described driven LED drive the output of branch road to be connected, and its anode is connected with power voltage terminal.
5. LED drive circuit according to claim 1, is characterized in that, one of them LED drives the first input end of the mistuning calibration function circuit in branch road also can be connected to the first link of the driving resistance in another LED driving branch road.
6. LED drive circuit according to claim 1, it is characterized in that, described mistuning calibration function circuit the first input end of described mistuning calibration function circuit voltage higher than the voltage of the second input and the first predetermined threshold and time, adjust its deviation calibration signal, described mistuning calibration function circuit is when the voltage of the first input end of described mistuning calibration function circuit is lower than the voltage of the second input and the second predetermined threshold poor, adjust its deviation calibration signal, the first input end of described mistuning calibration function circuit voltage lower than the voltage of the second input and the first predetermined threshold and and higher than the voltage of the second input and the second predetermined threshold poor time, keep its deviation calibration signal.
7. LED drive circuit according to claim 6, is characterized in that, described mistuning calibration function circuit comprises the first voltage comparator circuit, the second voltage comparator circuit and logical output circuit,
First voltage comparator circuit the first input end of described mistuning calibration function circuit voltage higher than the voltage of the second input and the first predetermined threshold and time, it exports the first signal, otherwise exports secondary signal;
Second voltage comparator circuit is when the voltage of the first input end of described mistuning calibration function circuit is lower than the voltage of the second input and the second predetermined threshold poor, and it exports the first signal, otherwise exports secondary signal;
Described logical output circuit is when the first voltage comparator circuit exports the first signal and the second voltage comparator circuit exports secondary signal, increase its deviation calibration signal, when the first voltage comparator circuit exports secondary signal and the second voltage comparator circuit exports the first signal, reduce its deviation calibration signal, when the first voltage comparator circuit exports secondary signal and the second voltage comparator circuit exports secondary signal, keep its deviation calibration signal.
8. LED drive circuit according to claim 1, it is characterized in that, described programmable operational amplifier comprises: the first difference transistor and the second difference transistor, wherein the first difference transistor or the second difference transistor include the differential crystal pipe unit of multiple parallel connection, each in Partial Differential transistor unit is connected with a programmable switch, the control end of described programmable switch receives described deviation calibration signal, under the control of described deviation calibration signal, described programmable switch conducting or cut-off.
9. LED drive circuit according to claim 1, it is characterized in that, described programmable operational amplifier comprises the multiple output resistances being positioned at the series connection exported on branch road, first link of each output resistance is connected with the output of described programmable operational amplifier by a programmable switch, the control end of described programmable switch receives described deviation calibration signal, under the control of described deviation calibration signal, described programmable switch conducting or cut-off.
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| CN114967810A (en) * | 2022-01-27 | 2022-08-30 | 成都利普芯微电子有限公司 | Constant current source calibration circuit, constant current source drive circuit, drive chip and electronic equipment |
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| CN106898310A (en) * | 2017-03-21 | 2017-06-27 | 京东方科技集团股份有限公司 | A kind of circuit, backlight, the display device of expansion LED quantity |
| CN113252949A (en) * | 2021-05-13 | 2021-08-13 | 北京芯格诺微电子有限公司 | High-precision current sampling circuit with on-chip real-time calibration |
| CN113252949B (en) * | 2021-05-13 | 2021-11-05 | 北京芯格诺微电子有限公司 | High-precision current sampling circuit with on-chip real-time calibration |
| CN114937433A (en) * | 2022-01-27 | 2022-08-23 | 成都利普芯微电子有限公司 | Constant-current driving circuit, driving chip and electronic device for LED display screen |
| CN114967810A (en) * | 2022-01-27 | 2022-08-30 | 成都利普芯微电子有限公司 | Constant current source calibration circuit, constant current source drive circuit, drive chip and electronic equipment |
| CN114937433B (en) * | 2022-01-27 | 2023-11-14 | 成都利普芯微电子有限公司 | LED display screen constant current drive circuit, drive chip and electronic equipment |
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| CN105208730B (en) | 2018-04-13 |
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