CN110120627A - Light emitting element driving circuit - Google Patents
Light emitting element driving circuit Download PDFInfo
- Publication number
- CN110120627A CN110120627A CN201810796571.9A CN201810796571A CN110120627A CN 110120627 A CN110120627 A CN 110120627A CN 201810796571 A CN201810796571 A CN 201810796571A CN 110120627 A CN110120627 A CN 110120627A
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- China
- Prior art keywords
- light emitting
- emitting element
- driving circuit
- element driving
- feedback signal
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C27/00—Electric analogue stores, e.g. for storing instantaneous values
- G11C27/02—Sample-and-hold arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/395—Linear regulators
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/10—Controlling the light source
Abstract
A kind of light emitting element driving circuit includes: power-switching circuit, error amplifying circuit, sample-and-hold circuit, load current generation circuit and feed-forward capacitance.When the non-enabled stage, feedback signal is electrically connected to each other via sample-and-hold circuit and with the second reference voltage and is disconnected from each other with load node, and when turning the turnover time point in enabled stage in the non-enabled stage as a result, feed-forward capacitance samples a sampling voltage.When the enabled stage, feedback signal is disconnected from each other via sample-and-hold circuit and with the second reference voltage and is coupled to each other with load node, sampling voltage is maintained by feed-forward capacitance, so that in predetermined current rise time after time point of transferring, feedback signal and the first reference voltage have sufficiently large difference, so that load current rises within the predetermined current rise time to reach the first electric current level.
Description
Technical field
The present invention relates to a kind of light emitting element driving circuits, particularly relate to a kind of by the luminous member of sample-and-hold circuit promotion
The load instantaneous of part driving circuit reacts (load-transient response), so that load current can be in default electricity
Rapid increase in the rise time is flowed, to reach the light emitting element driving circuit of the electric current level of target.
Background technique
Please refer to Fig. 1 and Fig. 2.Fig. 1 marks the schematic diagram of the light emitting element driving circuit of the prior art.Fig. 2 marks existing
The waveform diagram of the operation signal of the light emitting element driving circuit of technology.
In the light emitting element driving circuit 100 of the prior art, when light emitting element driving circuit 100 is in the non-enabled stage
When low level (this means, enable signal EN be), the level of load current iLOAD is zero, and at this point, the feedback letter of the prior art
Number FB is in a very high voltage level (such as, but not limited to can be 1.6V), and corresponding error amplification signal COMP is for example
It is zero.(such as, but not limited to may be used conventionally, as this reference voltage VREF is set to a very low voltage level
For 0.2V).Therefore, as shown in Fig. 2, when the light emitting element driving circuit 100 of the prior art switchs to enabled rank in the non-enabled stage
When one turnover time point Ts of section (when this means, enable signal EN switchs to high levels by low level), feedback signal FB must be from originally
Very high voltage level (such as, but not limited to can be 1.6V) is reduced to a very low voltage level (such as, but not limited to can be
0.2V), therefore, in a period of time T1 after the time point Ts that transfers, the transition status not yet of error amplifying circuit 13, it is,
It is zero that its corresponding error amplification signal COMP, which is still maintained, therefore, power-switching circuit 12 still can not conversion electric power VIN with
Load current iLOAD is provided, as shown, load current iLOAD will be unable to quickly rise to a target in time T1
Electric current level Ip.This is a big disadvantage of the prior art.In time T1, load current iLOAD is only capable of drawing electricity from capacitor C2
Stream, however, such electric current level is still very low (waveform diagram of the load current Iload in time T1 as shown in Figure 2).
In addition, in the prior art, load current iLOAD is relevant to the level of feedback signal FB, therefore, the prior art it is another
One it is big the disadvantage is that: when feedback signal FB drop to it is also lower than the level of reference voltage VREF (such as, but not limited to can be 0.2V)
When, (overshoot) effect is rushed due to excessively upper, feedback signal FB may be down to such as, but not limited to 0.1V, due to load
Electric current iLOAD is relevant to the level of feedback signal FB, and therefore, too low feedback signal FB level will also result in load current
ILOAD can not quickly reach the electric current level Ip of its target, and wherein the electric current level Ip of target is, for example, to correspond to feedback signal
Load current level when FB is 0.2V.
The present invention is to propose a kind of light emitting element driving circuit for the above subject, is promoted by sample-and-hold circuit
The load instantaneous of light emitting element driving circuit reacts (load-transient response), so that load current is pre-
If in current rise time can rapid increase to reach the light emitting element driving circuit of the electric current level of target.
Summary of the invention
Just wherein a viewpoint says that the present invention provides a kind of light emitting element driving circuits, to provide a load current extremely
One light-emitting component, to drive the light-emitting component, which includes: a power-switching circuit, to according to one
Error amplification signal converts an input voltage and generates an output voltage in an output end and provide the load current to the hair
Optical element, the light-emitting component are coupled between the output end and a load node；One error amplifying circuit, according to one first reference
One difference of voltage and a feedback signal, generates the error amplification signal；One sample-and-hold circuit, be coupled to the feedback signal with
Between the load node；It is negative to be coupled together at this with the sample-and-hold circuit and the light-emitting component for one load current generation circuit
Node, one first electric current level of the load current generation circuit to determine the load current in an enabled stage are carried, and is used
The stage is enabled with Yu Yifei, determines one second electric current level of the load current；An and feed-forward capacitance (feed-forward
Capacitor), it is coupled between the output end and the feedback signal；Wherein, non-make when the light emitting element driving circuit is in this
When the energy stage, which is electrically connected to each other via the sample-and-hold circuit with one second reference voltage, and, the feedback letter
It number is disconnected from each other via the sample-and-hold circuit with the load node, switchs to the enabled stage in the non-enabled stage as a result,
One turnover time point when, the feed-forward capacitance sample a sampling voltage；Wherein, when the light emitting element driving circuit is in the enabled rank
Duan Shi, the feedback signal are disconnected from each other via the sample-and-hold circuit with second reference voltage, and, the feedback signal via
The sample-and-hold circuit and be coupled to each other with the load node, wherein the sampling voltage is maintained by the feed-forward capacitance so that in
In in a predetermined current rise time after the turnover time point, the feedback signal is sufficiently large with one with first reference voltage
Difference, and the load current is made to increase within the predetermined current rise time to reach the first electric current level.
Preferably implement in kenel a kind of, the level of second reference voltage is less than the level of first reference voltage.
Preferably implement in kenel a kind of, the level of second reference voltage is equal to the level of first reference voltage.
Preferably implement in kenel a kind of, enables the stage in this, the load current generation circuit is according to the load node
Voltage and determine the first electric current level.
Preferably implement in kenel a kind of, which is relevant to first reference voltage.
Preferably implement in kenel a kind of, which includes a voltage-controlled current source, should to basis
The voltage of load node and adjust the load current.
Preferably implement in kenel a kind of, which includes: a resistance；One first switch, with the resistance
It is one another in series and is coupled between the load node and the feedback signal；And a second switch, be coupled to the feedback signal with should
Between second reference voltage；Wherein when the light emitting element driving circuit is in the non-enabled stage, first switch control is
Be not turned on, and the second switch control for conducting, as a result, the feedback signal via the sample-and-hold circuit and with this second reference
Voltage is electrically connected to each other, and the feedback signal is disconnected from each other with the load node, and is somebody's turn to do when the light emitting element driving circuit is in
When the enabled stage, first switch control is conducting, and second switch control is is not turned on, as a result, the feedback signal with should
Second reference voltage is disconnected from each other, and the feedback signal is coupled to each other with the load node.
Preferably implement in kenel a kind of, which is in the enabled stage in the light emitting element driving circuit
When, feedforward (feed-forward) function is provided, thus the light emitting element driving circuit operates in a stable state, and this shines
The bandwidth of element driving circuit is higher than a preset frequency.
Preferably implement in kenel a kind of, which is relevant to the resistance value and the feedforward of the resistance
The product of the capacitance of capacitor.
Preferably implement in kenel a kind of, the predetermined current rise time is less than 1 microsecond (micro second, μ s).
Preferably implement in kenel a kind of, which includes that a linear voltage regulator or a switched-mode power supply supply
Answer device.
Preferably implement in kenel a kind of, which is 0.
Preferably implement in kenel a kind of, the sufficiently large difference is less than a preset voltage difference upper limit, so that should
Load current rises within the predetermined current rise time to reach the first electric current level.
Below by way of specific embodiment elaborate, should be easier to understand the purpose of the present invention, technology contents, feature and
The effect of it is realized.
Detailed description of the invention
Fig. 1 marks the schematic diagram of the light emitting element driving circuit of the prior art.
Fig. 2 marks the operation signal waveform diagram of the light emitting element driving circuit of the prior art.
Fig. 3 marks the block schematic diagram of an embodiment of light emitting element driving circuit of the invention.
Fig. 4 marks an embodiment schematic diagram of load current generation circuit of the invention.
Fig. 5 A marks specific embodiment schematic diagram when light emitting element driving circuit of the invention is in the non-enabled stage.
Fig. 5 B marks specific embodiment schematic diagram when light emitting element driving circuit of the invention is in the enabled stage.
Fig. 6 is shown, and corresponds to Fig. 5 A-5B, the operation signal waveform diagram of light emitting element driving circuit of the invention.
Fig. 7 A marks another specific embodiment signal when light emitting element driving circuit of the invention is in the non-enabled stage
Figure.
Fig. 7 B marks another specific embodiment schematic diagram when light emitting element driving circuit of the invention is in the enabled stage.
Fig. 8 is shown, and corresponds to Fig. 7 A-7B, the operation signal waveform diagram of light emitting element driving circuit of the invention.
Fig. 9 A marks an embodiment schematic diagram of power-switching circuit of the invention.
Fig. 9 B marks another embodiment schematic diagram of power-switching circuit of the invention.
Figure 10 A~10B shows the load instantaneous reaction (load-transient that the present invention promotes light emitting element driving circuit
Response waveform diagram) is measured.
Symbol description in figure
Light emitting element driving circuit known to 100
Reference voltage known to VREF
Time known to T1
200,300 light emitting element driving circuit
12 power-switching circuits
13 error amplifying circuits
14 load current generation circuits
141 voltage-controlled current sources
15 sample-and-hold circuits
C1 feed-forward capacitance
COMP error amplification signal
EN enable signal
ENb reverse phase enable signal
FB feedback signal
ILOAD load current
Ip the first electric current level
LD light-emitting component
NLD load node
OUT output end
R1 resistance
S1 first switch
S2 second switch
Tf predetermined current fall time
The Tr predetermined current rise time
Ts turnover time point
Tw pulse width
Δ V voltage difference
The cross-pressure of VC1 feed-forward capacitance
VOUT output voltage
Vsmpl sampling voltage
Vhold voltage level
The second reference voltage of VREF_a
The first reference voltage of VREF_b
Specific embodiment
Attached drawing in the present invention belongs to signal, is mostly intended to indicate coupling relationship and each signal waveform between each circuit
Between relationship, as circuit, signal waveform and frequency then and not according to ratio draw.
Please refer to Fig. 3 and Fig. 4.Fig. 3 marks the block schematic diagram of an embodiment of light emitting element driving circuit of the invention.
Fig. 4 marks an embodiment of load current generation circuit of the invention.
As shown in figure 3, light emitting element driving circuit 200 of the invention, shines to provide a load current iLOAD to one
Element LD, to drive light-emitting component LD that it is made to shine, wherein light-emitting component LD can be such as, but not limited to laser light emitting diode,
The light-emitting component of such high-energy needs high driving current, is generally mostly driven with pulse-type current to avoid such as overheat etc.
Problem, therefore (such as, but not limited to 1 is micro- within the very short predetermined current rise time for the needs of light emitting element driving circuit 200
Second), load current iLOAD rapid increase is controlled to reach the electric current level (such as, but not limited to 6A) of target.
As shown, in one embodiment, light emitting element driving circuit 200 of the invention may include: power supply conversion electricity
Road 12, an error amplifying circuit 13, a sample-and-hold circuit 15, a load current generation circuit 14 and a feed-forward capacitance
(feed-forward capacitor)C1。
In one embodiment, power-switching circuit 12 is to convert input voltage VIN according to an error amplification signal COMP
And an output voltage VO UT is generated in output end OUT, and provide load current iLOAD to light-emitting component LD.As shown in figure 3,
Light-emitting component LD is coupled between output voltage VO UT and a load node NLD.In one embodiment, the electric current of light-emitting component LD
It flows into end and is coupled to output voltage VO UT, and its electric current outflow end is coupled to load node NLD.
In one embodiment, as shown in Figure 9 A, power-switching circuit such as, but not limited to can be a linear voltage regulator, to
It converts input voltage VIN with such as linear power supply conversion regime according to error amplification signal COMP and generates output voltage VO UT
In output end OUT and load current iLOAD is provided to light-emitting component LD.In another embodiment, as shown in Figure 9 B, power supply turns
Changing circuit such as, but not limited to can be for a switched power supply, to according to error amplification signal COMP, for example to switch
Formula power supply conversion regime converts input voltage VIN and generates output voltage VO UT in output end OUT and provide load current
ILOAD to light-emitting component LD.
With continued reference to FIG. 3, error amplifying circuit 13 is according to an one first reference voltage VREF_b's and feedback signal FB
One difference generates error amplification signal COMP.In one embodiment, error amplification signal COMP=a* (the first reference voltage
VREF_b- feedback signal FB).Wherein, a indicates the magnifying power of error amplifying circuit 13.It should be noted that error amplifying circuit
Positive and negative terminal is to illustrative and not limiting as illustrated in the drawing in 13, similarly, the positive negative direction of error amplification signal COMP also phase
Together, under teachings of the present invention, those skilled in the art are implemented with different positive and negative sense when can change its configuration.
Sample-and-hold circuit 15 is coupled between feedback signal FB and load node NLD (about the present invention how by taking
The load instantaneous that sample holding circuit 15 promotes light emitting element driving circuit 200 and 300 reacts (load-transient
Response), so that load current iLOAD within the predetermined current rise time rapid increase to reach the electric current position of target
Quasi- feature and details, is detailed later).
Feed-forward capacitance C1 is coupled between output end OUT and feedback signal FB.Feed-forward capacitance C1 has a cross-pressure VC1, such as
Shown in Fig. 3.
Load current generation circuit 14 and sample-and-hold circuit 15 and light-emitting component LD are coupled together at load node
NLD.Load current generation circuit 14 is in enabled stage (enable signal EN refering to Fig. 3 and refering to the enable signal of Fig. 6
The waveform diagram of EN) determine the one first electric current level of load current iLOAD, and the stage is enabled (refering to making for Fig. 3 to Yu Yifei
Can signal EN and refering to Fig. 6 enable signal EN waveform diagram), determine load current iLOAD one second electric current level.One
In embodiment, the first electric current level Ip is such as, but not limited to 6A as the aforementioned, and the second electric current level such as, but not limited to can be such as Fig. 6
Shown in electric current level 0.
In one embodiment, load current generation circuit 14 determines the first electric current position according to the voltage of load node NLD
Quasi- Ip.In one embodiment, the first electric current level Ip is relevant to the first reference voltage VREF_b.For example, such as Fig. 3 and Fig. 4
It is shown, when VREF_b is set as 0.2V, and when the stable state in enabled stage, level (the namely load node of feedback signal FB
The voltage level of NLD) it is also approximately equal to 0.2V, in one embodiment, and when the level of feedback signal FB is 0.2V, the first electric current
Level Ip can correspond to 6A.
Please refer to Fig. 4.In one embodiment, load current generation circuit 14 is such as, but not limited to may include a voltage controlled current
Source 141.As shown in figure 4, voltage-controlled current source 141 is controlled by enable signal EN and is adjusted negative according to the voltage of load node NLD
Carry electric current iLOAD.In one embodiment, load current iLOAD is such as, but not limited to be proportional to the voltage level of load node NLD
(the namely level of feedback signal FB when the enabled stage).
Please refer to Fig. 5 A, Fig. 5 B and Fig. 6.Fig. 5 A marks light emitting element driving circuit of the invention and is in the non-enabled stage
Specific embodiment when (Disabled Phase).Fig. 5 B marks light emitting element driving circuit of the invention and is in the enabled stage
Specific embodiment when (Enabled Phase).Fig. 6 is shown, and corresponds to Fig. 5 A-5B, and light-emitting component of the invention drives electricity
The waveform diagram of the operation signal on road.
As shown in Fig. 5 A and Fig. 5 B, in one embodiment, sample-and-hold circuit 15 is such as, but not limited to can include: resistance
R1, first switch S1 and second switch S2.First switch S1 and resistance R1, which is one another in series, is coupled to load node NLD and feedback letter
Between number FB.Second switch S2 is coupled between feedback signal FB and the second reference voltage VREF_a.It should be noted that first opens
Closing the sequence that S1 and resistance R1 are one another in series, there is no restriction, in one embodiment, what first switch S1 and resistance R1 was one another in series
Sequence can be as shown in Fig. 5 A and Fig. 5 B.
Illustrate how the present invention promotes the load instantaneous of light emitting element driving circuit 200 by sample-and-hold circuit 15 below
It reacts (load-transient response), so that on load current iLOAD is quick within the predetermined current rise time
It rises to reach the feature and details of the electric current level of target.
As shown in Figure 5A, in one embodiment, when light emitting element driving circuit 200 is in the non-enabled stage, first is opened
Pass S1 is controlled by enable signal EN and the signal EN control that is enabled is is not turned on, and second switch S2 is controlled by such as, but not limited to
One reverse phase enable signal ENb and be inverted enable signal ENb control for conducting, as a result, feedback signal FB via sampling maintain electricity
Road 15 and be electrically connected to each other with the second reference voltage VREF_a, and feedback signal FB via sample-and-hold circuit and and load node
NLD is disconnected from each other.Light emitting element driving circuit 200 switchs to a turnover time point Ts (ginseng in enabled stage in the non-enabled stage as a result,
Read the waveform diagram of the enable signal EN of Fig. 6) when, feed-forward capacitance C1 samples a sampling voltage Vsmpl (refering to the output voltage of Fig. 6
The waveform diagram of VOUT and feedback signal FB).It is worth noting that, sampling voltage " Vsmpl " described here refers to feed-forward capacitance
Voltage level of the cross-pressure VC1 of C1 in the case where the non-enabled stage.
As shown in Figure 5 B, in one embodiment, when light emitting element driving circuit 200 is in the enabled stage, first switch
S1 is controlled by enable signal EN and the signal EN control that is enabled is conducting, and second switch S2 is controlled by a reverse phase enable signal
ENb and it is inverted enable signal ENb control to be not turned on, feedback signal FB is via sample-and-hold circuit 15 and with second as a result,
Reference voltage VREF_a is disconnected from each other, and, feedback signal FB via sample-and-hold circuit 15 and with load node NLD coupling each other
It connects.
As a result, when light emitting element driving circuit 200 is in the enabled stage, sampling voltage is maintained by feed-forward capacitance C1
Vsmpl (Vhold is approximately equal to Vsmpl in namely Fig. 6), so that in predetermined current rise time Tr after the time point Ts that transfers
(refering to the waveform diagram of the feedback signal FB of Fig. 6), feedback signal FB and the first reference voltage VREF_b have a sufficiently large difference
Value, and load current iLOAD is made to increase in predetermined current rise time Tr to reach the first electric current level Ip.
In one embodiment, feed-forward capacitance C1 provides feedforward when light emitting element driving circuit 200 is in the enabled stage
(feed-forward) function, to the loop compensation and Bandwidth adjustment as driving circuit 200, so that light-emitting component driving electricity
Road 200 is operable in a stable state, and the bandwidth of light emitting element driving circuit 200 can be higher than a preset frequency.It is worth note
It anticipates, in the present embodiment, feed-forward capacitance C1 of the invention has the function of feed forward function above-mentioned and sampling and maintenance simultaneously
Can, loop stability degree, bandwidth and the electric current rate of climb are combined, while not improving cost.
In one embodiment, the product of the resistance value of resistance R1 and the capacitance of feed-forward capacitance C1 determines light-emitting component driving
One time constant of the load instantaneous reaction (load-transient response) of circuit 200, wherein predetermined current rises
Time, Tr was relevant to time constant.In other words, predetermined current rise time Tr is relevant to the resistance value and feed-forward capacitance of resistance R1
The product of the capacitance of C1.
In one embodiment, predetermined current rise time Tr is such as, but not limited to smaller than 1 microsecond (micro second, μ
s).It is worth noting that, in the present invention, due to the value very little of predetermined current rise time Tr, in identical enabled letter
Under number operation, compared to preceding case, for load current iLOAD of the invention when the enabled stage, pulse width Tw is more negative than preceding case
Current-carrying pulse width significantly improves (as shown in Fig. 6 and Fig. 8), and in other words, light emitting element driving circuit of the invention can have
Effect improves the brightness or other parameters performance of light-emitting component LD.
In addition, in the light emitting element driving circuit 200 of the present embodiment, when light emitting element driving circuit 200 is in enabled
When the stage (when this means, enable signal EN is high levels), since the present embodiment includes sample-and-hold circuit 15, with as described above
Control details so that feedback signal FB is disconnected from each other via sample-and-hold circuit 15 with the second reference voltage VREF_a.Such as
This one, in predetermined current rise time Tr, the level of feedback signal FB will be from slightly lower than second reference voltage
The voltage level of VREF_a gradually rises up to the first reference voltage VREF_b by the trend of feedback control.This means, real one
It applies in example, when light emitting element driving circuit 200 is in the stable state in enabled stage, the level of feedback signal FB is approximately equal to the
One reference voltage VREF_b.
It should be noted that in the embodiment in fig 6, the level of the second reference voltage VREF_a is less than the first reference voltage
The level of VREF_b, however spirit according to the present invention is not limited to this, the level of the second reference voltage VREF_a also can be equal to,
Or the level slightly larger than the first reference voltage VREF_b, can still have effect of the invention, wherein the second reference voltage VREF_a
The embodiment of level of the level equal to the first reference voltage VREF_b be detailed later.
In the present embodiment, when light emitting element driving circuit 200 is in the enabled stage, (this means, enable signal EN is height
When level), since load current iLOAD is relevant to feedback signal FB, (when the stable state in enabled stage, level is approximately equal to
First reference voltage VREF_b), and since the level of feedback signal FB from the second reference voltage VREF_a rises to the first reference
Time needed for voltage VREF_b is very short, and therefore, compared to the prior art, the load current generation circuit 14 of the present embodiment is in making
It, can be according to voltage (the namely level of feedback signal FB) the quick decision load current iLOAD of load node NLD when the energy stage
The first electric current level Ip, as a result, load current iLOAD within the predetermined current rise time Tr can rapid increase to reach mesh
Target electric current level Ip.For a viewpoint, the second reference voltage VREF_a and the first reference voltage VREF_b can be suitably selected
Relationship (i.e. size and difference), make to tie up after the light emitting element driving circuit switchs to the enabled stage by the feed-forward capacitance
Hold the sampling voltage, in the predetermined current rise time after the turnover time point, the feedback signal above-mentioned and this first
The sufficiently large difference is less than a preset voltage difference upper limit between reference voltage, so that load current generation circuit is pre- one
If determining the first electric current level in current rise time.
Please refer to Fig. 7 A, Fig. 7 B and Fig. 8.Fig. 7 A marks light emitting element driving circuit of the invention and is in the non-enabled stage
Another specific embodiment when (Disabled Phase).Fig. 7 B marks light emitting element driving circuit of the invention and is in enabled rank
Another specific embodiment when section (Enabled Phase).Fig. 8 is shown, and corresponds to Fig. 7 A-7B, and light-emitting component of the invention drives
The waveform diagram of the operation signal of dynamic circuit.
Light emitting element driving circuit 300 shown in Fig. 7 A-7B is approximately similar to the driving electricity of light-emitting component shown in Fig. 5 A-5B
Road 200, difference is: in the embodiment of light emitting element driving circuit 300 shown in Fig. 7 A-7B, the second reference voltage
The level of VREF_a is equal to the level of the first reference voltage VREF_b.The light emitting element driving circuit 300 shown in Fig. 7 A-7B
In embodiment, such as, but not limited to the second reference voltage VREF_a can be coupled directly to the first reference voltage VREF_b.
In this way, as shown in Figure 7 A, in one embodiment, when light emitting element driving circuit 300 is in the non-enabled stage
When, first switch S1 is controlled by enable signal EN and the signal EN control that is enabled is is not turned on, and second switch S2 is controlled by one
Reverse phase enable signal ENb and be inverted enable signal ENb control for conducting, feedback signal FB is via sample-and-hold circuit as a result,
15 and be electrically connected to each other with the first reference voltage VREF_b, and feedback signal FB via sample-and-hold circuit and and load node
NLD is disconnected from each other.Light emitting element driving circuit 300 switchs to a turnover time point Ts (ginseng in enabled stage in the non-enabled stage as a result,
Read the waveform diagram of the enable signal EN of Fig. 8) when, feed-forward capacitance C1 samples a sampling voltage Vsmpl (refering to the output voltage of Fig. 8
The waveform diagram of VOUT and feedback signal FB).It is worth noting that, sampling voltage Vsmpl described here, " Vsmpl " therein
Refer to voltage level of the cross-pressure VC1 of feed-forward capacitance C1 in the case where the non-enabled stage.
As shown in Figure 7 B, in one embodiment, when light emitting element driving circuit 200 is in the enabled stage, first switch
S1 is controlled by enable signal EN and the signal EN control that is enabled is conducting, and second switch S2 is controlled by a reverse phase enable signal
ENb and it is inverted enable signal ENb control to be not turned on, feedback signal FB is via sample-and-hold circuit 15 and with first as a result,
Reference voltage VREF_b is disconnected from each other, and, feedback signal FB via sample-and-hold circuit 15 and with load node NLD coupling each other
It connects.
As a result, when light emitting element driving circuit 300 is in the enabled stage, sampling voltage is maintained by feed-forward capacitance C1
Vsmpl (Vhold is approximately equal to Vsmpl in namely Fig. 8), so that in predetermined current rise time Tr after the time point Ts that transfers
(refering to the waveform diagram of the feedback signal FB of Fig. 8), feedback signal FB and the first reference voltage VREF_b have a sufficiently large difference
Value, and load current iLOAD is made to increase in a predetermined current rise time Tr to reach the first electric current level Ip.
Compared to the prior art, the load current iLOAD of the light emitting element driving circuit 300 of the present embodiment is in predetermined current
In rise time Tr can rapid increase to reach the electric current level Ip of target.Illustrate following with Fig. 6 and Fig. 8 of the invention and existing
There is the difference of technology: it is, the present invention is able to ascend the load instantaneous reaction (load- of light emitting element driving circuit 200
Transient response) so that load current iLOAD within the predetermined current rise time rapid increase to reach mesh
Target electric current level.
In the light emitting element driving circuit 200 and 300 of the present embodiment, make when light emitting element driving circuit 200 is in non-
When the energy stage (when this means, enable signal EN is low level), since the present invention includes sample-and-hold circuit 15, as described above
Details is controlled, so that feedback signal FB is electrically connected to each other via sample-and-hold circuit 15 with the second reference voltage VREF_a,
In the second reference voltage VREF_a level lower than (Fig. 6) or be equal to (Fig. 8) first reference voltage VREF_b level.Such one
Coming, feedback signal FB compared to the prior art is in a very high voltage level (such as, but not limited to can be 1.6V), this
The feedback signal FB of invention is being coupled to the second reference voltage VREF_a or the first reference voltage when the non-enabled stage
VREF_b, that is, be slightly less than or the target value to be reached (the first reference voltage VREF_b) when equal to the enabled stage.In this way
The advantages of be: as shown in Fig. 6 or Fig. 8, when the light emitting element driving circuit 200 or 300 of the present embodiment switchs in the non-enabled stage
Enabled stage (when this means, enable signal EN is high levels) as soon as turnover time point Ts when, feedback signal FB is necessarily from script
Very high voltage level is reduced to a very low voltage level, can so effectively shorten reaction time of feedback signal FB,
And then improve the speed that electric current rises.
Further, since output voltage VO UT is reduced because of load current iLOAD, pass through the sampling and maintenance of feed-forward capacitance C1
Function (namely such as the Vsmpl and Vhold in Fig. 6 or Fig. 8)), (such as scheme within a period of time after the time point Ts that transfers
The leading portion of predetermined current rise time Tr in 6 or Fig. 8), the level of feedback signal FB from the second reference voltage VREF_a and exports
Voltage VOUT generally synchronously reduce (due in Fig. 6 or Fig. 8 in the leading portion of predetermined current rise time Tr feed-forward capacitance C1 across
Pressure VC1 be still generally maintained turnover time point on sample obtained by voltage level Vhold, be approximately equal to Vsmpl) to one slightly
Voltage level (being lower than the first reference voltage VREF_b) lower than the second reference voltage VREF_a, corresponding error amplification is believed at this time
Number COMP will quick response or transition (such as being rapidly reduced to a low level from the high levels of script in Fig. 6), it is electric as a result,
Power-switching circuit 12 can rapidly provide load current iLOAD, therefore, in predetermined current rise time Tr, load current
ILOAD can rapidly rise to the electric current level Ip of target.
Figure 10 A~10B is please referred to, the load instantaneous reaction (load- that the present invention promotes light emitting element driving circuit is shown
Transient response) measurement waveform diagram.As shown in Figure 10 A, the load of the light emitting element driving circuit of the present embodiment
Electric current iLOAD within the predetermined current rise time Tr can rapid increase to reach the electric current level of target.Figure 10 B is Figure 10 A
Enlarged diagram be more clearly visible the load current of the light emitting element driving circuit of the present embodiment as shown in Figure 10 B
ILOAD within the predetermined current rise time Tr can rapid increase to reach the electric current level of target.
Illustrate the present invention for preferred embodiment above, but described above, is only easy to those skilled in the art
Understand the contents of the present invention, interest field not for the purpose of limiting the invention.Under same spirit of the invention, art technology
Personnel are contemplated that various equivalence changes.For example, can plant not influences the main function of circuit between the shown circuit element being directly connected to
The circuit element of energy, such as switch or resistance.In another example aforementioned first switch S1 is controlled by enable signal EN, and second switch
S2 is controlled by reverse phase enable signal ENb, this is only for example rather than limits, when first switch S1 is different kenels from second switch S2
Transistor when, can also all be controlled by enable signal EN.All this kind, according to the present invention can all teach and analogize and obtain.In addition,
Illustrated each embodiment, however it is not limited to it is used alone, it can also be with combined application, such as, but not limited to simultaneously by two embodiments
With, or replaced the corresponding circuits of another embodiment with the local circuit of one of embodiment.Therefore, the scope of the present invention is answered
Cover above-mentioned and other all equivalence changes.In addition, any implementation kenel of the invention is not necessarily to realize all purposes or excellent
Point, therefore, any one of claim also should not be as limits.
Claims (13)
1. a kind of light emitting element driving circuit, should to drive the light-emitting component to provide a load current a to light-emitting component
Light emitting element driving circuit includes:
One power-switching circuit, to convert an input voltage and generate an output voltage in one according to an error amplification signal
Output end and provide the load current to the light-emitting component, the light-emitting component be coupled to the output end and a load node it
Between；
One error amplifying circuit generates the error amplification signal according to a difference of one first reference voltage and a feedback signal；
One sample-and-hold circuit is coupled between the feedback signal and the load node；
One load current generation circuit is coupled together at the load node with the sample-and-hold circuit and the light-emitting component, this is negative
One first electric current level of the current generating circuit to determine the load current in an enabled stage is carried, and enabled to Yu Yifei
Stage determines one second electric current level of the load current；And
One feed-forward capacitance is coupled between the output end and the feedback signal；
Wherein, when the light emitting element driving circuit is in the non-enabled stage, the feedback signal is via the sample-and-hold circuit
And be electrically connected to each other with one second reference voltage, and, the feedback signal via the sample-and-hold circuit and with the load node that
This is disconnected, and when switching to a turnover time point in the enabled stage in the non-enabled stage as a result, which samples electricity
Pressure；
Wherein, when the light emitting element driving circuit is in the enabled stage, the feedback signal via the sample-and-hold circuit and
Be disconnected from each other with second reference voltage, and, the feedback signal via the sample-and-hold circuit and with load node coupling each other
It connects, wherein the sampling voltage is maintained by the feed-forward capacitance, so that the predetermined current rise time after the turnover time point
Interior, the feedback signal and first reference voltage have a sufficiently large difference, and make the load current in the predetermined current
Rise in rise time to reach the first electric current level.
2. light emitting element driving circuit as described in claim 1, wherein the level of second reference voltage is less than first ginseng
Examine the level of voltage.
3. light emitting element driving circuit as described in claim 1, wherein the level of second reference voltage is equal to first ginseng
Examine the level of voltage.
4. light emitting element driving circuit as described in claim 1, wherein the stage is enabled in this, the load current generation circuit root
The first electric current level is determined according to the voltage of the load node.
5. light emitting element driving circuit as claimed in claim 4, wherein the first electric current level is relevant to the first reference electricity
Pressure.
6. light emitting element driving circuit as claimed in claim 4, wherein the load current generation circuit includes a voltage controlled current
Source adjusts the load current to the voltage according to the load node.
7. light emitting element driving circuit according to any one of claims 1 to 6, wherein the sample-and-hold circuit includes:
One resistance；
One first switch is one another in series with the resistance and is coupled between the load node and the feedback signal；And
One second switch is coupled between the feedback signal and second reference voltage；
Wherein when the light emitting element driving circuit is in the non-enabled stage, first switch control to be not turned on, and this
Two switch controls are conducting, and the feedback signal is electrically connected via the sample-and-hold circuit with second reference voltage each other as a result,
It connects, and the feedback signal is disconnected from each other with the load node, and when the light emitting element driving circuit is in the enabled stage, it should
First switch control is conducting, and second switch control is is not turned on, as a result, the feedback signal and second reference voltage that
This is disconnected, and the feedback signal is coupled to each other with the load node.
8. light emitting element driving circuit as described in claim 1, wherein the feed-forward capacitance is at the light emitting element driving circuit
When this enables the stage, feed forward function is provided, thus the light emitting element driving circuit operates in a stable state, and the member that shines
The bandwidth of part driving circuit is higher than a preset frequency.
9. light emitting element driving circuit as claimed in claim 7, wherein the predetermined current rise time is relevant to the resistance
The product of the capacitance of resistance value and the feed-forward capacitance.
10. light emitting element driving circuit as described in claim 1, wherein the predetermined current rise time is less than 1 microsecond.
11. light emitting element driving circuit as described in claim 1, wherein the power-switching circuit include a linear voltage regulator or
One switched power supply.
12. light emitting element driving circuit as described in claim 1, wherein the second electric current level is 0.
13. light emitting element driving circuit as described in claim 1, wherein the sufficiently large difference is less than a preset voltage difference
It is worth the upper limit, so that the load current rises within the predetermined current rise time to reach the first electric current level.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201862627109P | 2018-02-06 | 2018-02-06 | |
| US62/627,109 | 2018-02-06 |
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| CN110120627B CN110120627B (en) | 2020-09-01 |
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| CN201810796571.9A Active CN110120627B (en) | 2018-02-06 | 2018-07-19 | Light emitting element drive circuit |
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Cited By (1)
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| CN110995049A (en) * | 2019-12-23 | 2020-04-10 | 苏州易德龙科技股份有限公司 | Method for improving current response speed of pulse power supply |
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| Publication number | Publication date |
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| TWI659671B (en) | 2019-05-11 |
| TW201936009A (en) | 2019-09-01 |
| CN110120627B (en) | 2020-09-01 |
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