CN205546101U - Light -emitting diode (LED) driving circuit - Google Patents
Light -emitting diode (LED) driving circuit Download PDFInfo
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- CN205546101U CN205546101U CN201620351760.1U CN201620351760U CN205546101U CN 205546101 U CN205546101 U CN 205546101U CN 201620351760 U CN201620351760 U CN 201620351760U CN 205546101 U CN205546101 U CN 205546101U
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Abstract
The utility model provides a light -emitting diode (LED) driving circuit is through the DCDC converting unit and the load of stationary flow unit common drive LED of output series connection, it obtains the output ripple of stationary flow unit and generates ripple signal relevant with it to obtain the unit through feedback signal, by feedback signal processing unit according to ripple signal output feedback signal, through the sampled signal of DCDC the control unit according to feedback signal, direct current base mark signal and sign DCDC converting unit output voltage, generate control signal at last, control signal is when light -emitting diode (LED) driving circuit job stabilization, and the output voltage ripple that can control DCDC converting unit is opposite with the phase place of the output voltage ripple of stationary flow unit, makes the ripple in the LED load reduce elimination even, avoid output current to have great ripple and cause the LED lamp stroboscopic phenomenon to appear, and when light -emitting diode (LED) driving circuit work was unstable, control DCDC converting unit's output parameter made it stably.
Description
Technical field
This utility model relates to LED actuation techniques field, particularly relates to a kind of LED drive circuit.
Background technology
LED, as a kind of novel illumination device, owing to its luminous efficiency is high, is widely used in illumination neck
Territory, and it typically requires constant-current driving, the LED driver driven as its current stabilization in the prior art is normal
Use single-stage solution.
And use the LED driver of single-stage solution, owing to PFC (Power Factor taken into account by needs
Correction, PFC) function, i.e. it controls loop needs the slowest response speed just can have
Higher PF (Power Factor, power factor) value, therefore, it is relatively slow that it controls loop response speed,
And this can cause output electric current to have bigger ripple, the cycle of this ripple is the input ac voltage cycle
Half.When LED driver connects load, this current ripples will cause LED stroboscopic phenomenon occur,
This stroboscopic phenomenon will affect the service life of LED, also have certain damage to human eye.Particularly,
Under low temperature environment, ripple can be bigger.This is because (the most subzero 40 °) electrochemical capacitor under low temperature environment
Capacitance decline to a great extent, cause output ripple to be significantly increased, especially for single-level circuit, under low temperature
The situation that output ripple is significantly increased becomes apparent from.
Utility model content
In view of this, this utility model provides a kind of LED drive circuit, can not only solve prior art
Output electric current has bigger ripple and causes LED the problem of stroboscopic phenomenon occur, but also can be real
The function of the most efficient and high PF value, particularly also ensures that circuit can steady operation when low temperature environment.
To achieve these goals, the technical scheme that this utility model embodiment provides is as follows:
A kind of LED drive circuit, including:
Control the steady flow unit of described LED drive circuit output stabling current value；
With the DC/DC converter unit that described steady flow unit drives LED load jointly, described steady flow unit
And the outfan series connection of described DC/DC converter unit；
Obtain the output ripple of described steady flow unit, and generate the anti-of ripple signal according to described output ripple
Feedback signal acquiring unit；Described output ripple includes: output current ripple and/or output voltage ripple；Institute
The outfan of the input and described steady flow unit of stating feedback signal acquiring unit is connected；
Receive described ripple signal, and export the anti-of associated feedback signal according to described ripple signal
Feedback signal processing unit；
Obtain described feedback signal and a sampling letter characterizing described DC/DC converter unit output voltage
Number, obtain or built-in DC reference signal, and according to described sampled signal, described feedback signal and described
DC reference signal generates the DC/DC control unit controlling signal to described DC/DC converter unit；Institute
Stating control signal is to control described DC/DC converter unit when described LED drive circuit working stability
The opposite in phase of output voltage ripple of output voltage ripple and described steady flow unit, drive at described LED
During the job insecurity of galvanic electricity road, the output voltage controlling described DC/DC converter unit is zero or controls institute
State DC/DC converter unit output voltage ripple reduce or be zero control signal；Described DC/DC is controlled
The feedback end of unit processed is connected with the outfan of described feedback signal processing unit.
Preferably, described feedback signal processing unit includes: switch；
Described switch is connected to the outfan of described feedback signal acquiring unit and described DC/DC control unit
Feedback end between；
The control end of described switch receives switching signal；
Described switching signal is when the ripple of output voltage of described steady flow unit is more than the first preset range
Time, control the switching signal of described switch OFF.
Preferably, described feedback signal processing unit includes: switch, the first resistance and the second resistance；
Described switch is connected to the outfan of described feedback signal acquiring unit and described DC/DC control unit
Feedback end between；
Described first resistance and described switch in parallel；
One end ground connection of described second resistance, the other end of described second resistance and described DC/DC control single
The feedback end of unit is connected；
The control end of described switch receives switching signal；
Described switching signal is when the ripple of output voltage of described steady flow unit is more than the second preset range
Time, control the switching signal of described switch OFF.
Preferably, described feedback signal processing unit includes: clamp circuit；
Described clamp circuit and described feedback signal acquiring unit be parallel to the outfan of described steady flow unit with
Between the feedback end of described DC/DC control unit；
Described clamp circuit is when the ripple of output voltage of described steady flow unit is more than the 3rd preset range
Time, obtain the clamp circuit of described feedback signal after described ripple signal is carried out clamper.
Preferably, the outfan of described feedback signal acquiring unit and described feedback signal processing unit is defeated
Enter end to be connected；
Described DC/DC control unit also includes the ripple end receiving described ripple signal, described ripple end with
The outfan of described feedback signal acquiring unit is connected；
Described feedback signal processing unit is when the ripple of the output voltage of described steady flow unit is pre-more than the 4th
If during scope, the described feedback signal of output controls described DC/DC by described DC/DC control unit
The output voltage of converter unit is the feedback signal processing unit of zero.
Preferably, described DC/DC control unit includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is that described DC/DC controls list
The reference edge of unit, receives described DC reference signal, and another input of described subtractor is described DC/DC
The feedback end of control unit, receives described feedback signal；The outfan of described subtractor and described first collection
The input becoming amplifier is connected；Another input of described first integrated transporting discharging is described DC/DC
The sampling end of control unit, receives described sampled signal；
Or, described DC/DC control unit includes: adder and the second integrated transporting discharging；Described adder
The feedback end that an input is described DC/DC control unit, receive described feedback signal；Described add
Another input of musical instruments used in a Buddhist or Taoist mass is the sampling end of described DC/DC control unit, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
Another input of amplifier is the reference edge of described DC/DC control unit, receives described DC reference letter
Number.
Preferably, described DC/DC control unit includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is that described DC/DC controls list
The reference edge of unit, receives described DC reference signal, and another input of described subtractor is described DC/DC
The ripple end of control unit, receives described ripple signal；The outfan of described subtractor and described first collection
The input becoming amplifier is connected；Another input of described first integrated transporting discharging is described DC/DC
The sampling end of control unit, receives described sampled signal；
Or, described DC/DC control unit includes: adder and the second integrated transporting discharging；Described adder
The ripple end that an input is described DC/DC control unit, receive described ripple signal；Described add
Another input of musical instruments used in a Buddhist or Taoist mass is the sampling end of described DC/DC control unit, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
Another input of amplifier is the reference edge of described DC/DC control unit, receives described DC reference letter
Number.
Preferably, described feedback signal processing unit includes: controls described feedback signal and believes with described ripple
Number ratio vary with temperature and the temperature detection bleeder circuit that changes in the same direction；Described temperature detection dividing potential drop electricity
The input on road is connected with the outfan of described feedback signal acquiring unit, described temperature detection bleeder circuit
Outfan be connected with the feedback end of described DC/DC control unit.
Preferably, described feedback signal acquiring unit includes: for obtaining the output voltage of steady flow unit
The block isolating circuit of AC compounent.
Preferably, the described sampled signal that described DC/DC control unit receives converts from described DC/DC
The outfan of unit obtains.
The application provides a kind of LED drive circuit, controls described LED drive circuit by steady flow unit defeated
Go out stable current value；The DC/DC converter unit connected by outfan is driven jointly with described steady flow unit
Dynamic LED load；By the output ripple of the feedback signal acquiring unit described steady flow unit of acquisition, and according to
Described output ripple generates ripple signal；Described ripple signal, and root is received by feedback signal processing unit
According to the feedback signal that the output of described ripple signal is associated；Institute is obtained finally by DC/DC control unit
State feedback signal and a sampled signal characterizing described DC/DC converter unit output voltage, obtain or interior
Put DC reference signal, and according to described sampled signal, described feedback signal and described DC reference signal
Generation controls signal to described DC/DC converter unit；Described control signal is at described LED drive circuit
During working stability, it is possible to control the output voltage ripple of described DC/DC converter unit and described steady flow unit
The opposite in phase of output voltage ripple, make the ripple in LED load reduce and even eliminate, it is to avoid output
Electric current has bigger ripple and causes LED stroboscopic phenomenon occur.Or at described LED drive circuit
During job insecurity, controlled the output voltage ripple of described DC/DC converter unit by described control signal
Reducing or be zero, or the output voltage controlling described DC/DC converter unit is zero, with avoid described surely
The excessive situation causing described DC/DC converter unit job insecurity of output ripple of stream unit occurs.
Accompanying drawing explanation
In order to be illustrated more clearly that this utility model embodiment or technical scheme of the prior art, below will
The accompanying drawing used required in embodiment or description of the prior art is briefly described, it should be apparent that,
Accompanying drawing in describing below is only embodiment of the present utility model, comes for those of ordinary skill in the art
Say, on the premise of not paying creative work, it is also possible to obtain other accompanying drawing according to the accompanying drawing provided.
The structural representation of a kind of LED drive circuit that Fig. 1 provides for the embodiment of the present application；
A kind of signal waveforms that Fig. 2 provides for the application one embodiment；
Another signal waveforms that Fig. 3 provides for the application one embodiment；
The structural representation of a kind of DC/DC control unit that Fig. 4 provides for another embodiment of the application；
The structural representation of another LED drive circuit that Fig. 5 provides for another embodiment of the application；
The structural representation of another LED drive circuit that Fig. 6 provides for another embodiment of the application；
The structural representation of another LED drive circuit that Fig. 7 provides for another embodiment of the application；
The structural representation of another LED drive circuit that Fig. 8 provides for another embodiment of the application.
Detailed description of the invention
Below in conjunction with the accompanying drawing in this utility model embodiment, to the technology in this utility model embodiment
Scheme is clearly and completely described, it is clear that described embodiment is only this utility model one
Divide embodiment rather than whole embodiments.Based on the embodiment in this utility model, this area is common
The every other embodiment that technical staff is obtained under not making creative work premise, broadly falls into this
The scope of utility model protection.
This utility model provides a kind of LED drive circuit, can not only solve prior art output electric current tool
There is bigger ripple to cause LED that the problem of stroboscopic phenomenon occurs, but also can realize efficient and high
The function of PF value, particularly also ensures that circuit can steady operation when low temperature environment.
Concrete, as it is shown in figure 1, described LED drive circuit includes: steady flow unit 101, DC/DC
Converter unit 102, feedback signal acquiring unit 103, feedback signal processing unit 104 and DC/DC are controlled
Unit 105 processed；
The outfan series connection of steady flow unit 101 and DC/DC converter unit 102；
The input of feedback signal acquiring unit 103 is connected with the outfan of steady flow unit 101；
The input of feedback signal processing unit 104 is connected with the outfan of feedback signal acquiring unit 103；
The feedback end of DC/DC control unit 105 is connected with the outfan of feedback signal processing unit 104.
What deserves to be explained is, the anode of the outfan of steady flow unit 101 and the positive pole of LED load in Fig. 1
Being connected, the negative terminal of the outfan of DC/DC converter unit 102 is connected with the negative pole of described LED load；?
In actual application, it would however also be possible to employ the anode of the outfan of DC/DC converter unit 102 and LED load
Positive pole be connected, the negative terminal of the outfan of steady flow unit 101 is connected with the negative pole of described LED load；Figure
1 is only a kind of example, steady flow unit 101 and DC/DC converter unit 102 and the company of described LED load
Connect mode and be not specifically limited, can be according to the applied environment of its reality depending on.
Concrete operation principle is:
Steady flow unit 101 controls the current value that the output of described LED drive circuit is stable；
The DC/DC converter unit 102 of outfan series connection and steady flow unit 101 are provided commonly for driving LED
Load；
Feedback signal acquiring unit 103 obtains the output ripple of steady flow unit 101, and according to described output
Ripple generates the ripple signal Vp characterizing described output ripple size；
Preferably, described output ripple includes: output current ripple and/or output voltage ripple.
Feedback signal processing unit 104 receives ripple signal Vp, and exports therewith according to ripple signal Vp
Relevant feedback signal VFB；
DC/DC control unit 105 obtains feedback signal VFB and a sign DC/DC converter unit 102
Sampled signal VS of output voltage V2, and obtain or built-in DC reference signal Vref, and according to adopting
Sample signal VS, feedback signal VFB and DC reference signal Vref generate control signal VC to DC/DC
Converter unit 102, controls the output of DC/DC converter unit 102, specific as follows:
When LED drive circuit working stability, especially DC/DC converter unit 102 working stability are (steady
The output voltage V1 ripple of stream unit 101 is less) time, the control signal of DC/DC control unit 105
VC controls DC/DC converter unit 102 so that the output ripple of DC/DC converter unit 102 and current stabilization
The output ripple opposite in phase of unit 101, reduces with this and even eliminates the ripple in LED load.
And when the output ripple of steady flow unit 101 makes the most greatly DC/DC converter unit 102 job insecurity,
Control signal VC controls DC/DC converter unit 102 so that the output stricture of vagina of DC/DC converter unit 102
Ripple reduces or is zero or direct closedown DC/DC converter unit 102 so that it is not output voltage.
What deserves to be explained is, in concrete actual application, DC/DC converter unit 102 can be buck
The DC/DC converter units such as converter unit or boost converter unit；
When DC/DC converter unit 102 is buck converter unit, cause buck converter unit unstable
Factor be: the output voltage V2 of buck converter unit is continuously more than its input voltage vin or it is defeated
Go out voltage V2 and the situation less than or equal to 0 occurs continuously.As in figure 2 it is shown, the output of buck converter unit
Voltage V2 should meet V2 ∈ [0, Vin], just can be at stable duty.
In like manner, when DC/DC converter unit 102 is boost converter unit, boost converter unit is caused
The factors of instability are: the output voltage of boost converter unit is less than its input voltage or its output voltage
The highest (output voltage is the highest causes dutycycle very big, and circuit is likely to instability).
And the output voltage V2 of DC/DC converter unit 102 is the base by DC/DC control unit 105
Calibration signal controls.As shown in Figure 4, for doing with sampled signal VS in DC/DC control unit 105
Reference signal relatively is actually (Vref-VFB)；Therefore, < Vmax can not only to arrange 0 < Vref
Ensure 0 < Vref-VFB < Vmax (Vmax be circuit sampling signal etc. constant in the case of corresponding BUCK
The maximum reference signal of the maximum allowable output voltage Vomax of circuit, Vomax=Vin).The present embodiment
In order to eliminate ripple, for the benchmark letter compared with sampled signal VS in DC/DC control unit 105
Number no longer the same with prior art is a DC quantity (DC reference signal Vref), but one and current stabilization
The amount (Vref-VFB) that the output ripple of unit 101 is relevant.So, when DC/DC converter unit 102
During for buck converter unit, feedback signal VFB of feedback signal processing unit 104 output should make DC/DC
Less than certain value Vmax, (Vmax is circuit sampling letter to the reference signal (Vref-VFB) of control unit 105
Number etc. constant in the case of the maximum benchmark letter of maximum allowable output voltage Vomax of corresponding BUCK circuit
Number Vomax=Vin), namely need to meet condition: (Vref-VFB) ∈ [0, Vmax], such as Fig. 3 institute
Show.
And when DC/DC converter unit 102 is boost converter unit, feedback signal processing unit 104
Feedback signal VFB of output should make in DC/DC control unit 105 for comparing with sampled signal VS
Reference signal meet condition: (Vref-VFB) > (Vmin is that circuit sampling signal etc. is constant to Vmin
In the case of the minimum minimum reference signal allowing output voltage Vomin of corresponding boost converter unit,
Vomin=Vin).
From the above mentioned, the present embodiment by feedback signal processing unit 104 to ripple signal Vp process
After obtain associated feedback signal VFB, then feedback signal VFB be input to DC/DC control single
Unit 105, makes in DC/DC control unit 105 for the reference signal compared with sampled signal VS
(Vref-VFB) corresponding condition is met, it is to avoid directly inputted as feedback signal by ripple signal Vp
To DC/DC control unit 105, when ripple signal Vp is the biggest, DC/DC converter unit 102 works
Unstable situation occurs.
The described LED drive circuit that the present embodiment provides, by above-mentioned connected mode and operation principle,
During normal circuit operation, generate control signal VC to DC/DC converter unit 102, control DC/DC and become
Change the opposite in phase of the output voltage ripple of unit 102 and the output voltage ripple of steady flow unit 101, make
Ripple reduction in LED load even eliminates, it is to avoid output electric current has bigger ripple and causes LED
There is stroboscopic phenomenon in lamp.
And when the output ripple of steady flow unit 101 causes the most greatly DC/DC converter unit 102 job insecurity
Time, by control signal VC control DC/DC converter unit 102 output voltage ripple reduce or be zero,
Or directly closing DC/DC converter unit 102, the output voltage controlling DC/DC converter unit 102 is
Zero, work shakiness with the output ripple excessive DC/DC of the causing converter unit 102 avoiding steady flow unit 101
Fixed situation occurs.
What deserves to be explained is, in prior art, cause in order to avoid output electric current has bigger ripple
The stroboscopic phenomenon that LED occurs, the LED driver of employing two-step scheme is also by more selection, thereafter
The input directly outfan with prime AC-DC converter of level DC-DC converter is connected, described before
Level AC-DC converter is used for realizing PFC function, and described rear class DC-DC converter is used for realizing constant current
Or pressure-keeping functions, the control loop response speed of prime AC-DC converter can be very slow, without causing
LED driver output current ripple problem, the control loop response speed of rear class DC-DC converter is permissible
Comparatively fast, meet quickly adjust and reduce output current ripple demand, it is easy to solution single-stage solution exist
Problem.
But two-step scheme has carried out two times transfer due to input power, the efficiency making LED driver is two
The efficiency product of level circuit.Such as front stage circuits efficiency is η 1, and late-class circuit efficiency is η 2, the most existing skill
Art uses the efficiency eta=η 1 × η 2 of the LED driver of two-step scheme, greatly reduces LED driver
Efficiency, increases loss, it is impossible to highlight the advantage that LED illumination System is energy-conservation.
And use the LED drive circuit that the present embodiment provides, by above-mentioned connected mode and control principle,
While realizing low ripple output and ensureing higher PF value, if the efficiency of steady flow unit 101 is η 1,
The efficiency of DC/DC converter unit 102 is η 2, and the efficiency eta of the most described LED drive circuit is only slightly less than η 1,
The efficiency eta of the described LED drive circuit degree less than η 1 depends on that DC/DC converter unit 102 processes
The size of power, compared to existing technology in use the LED driver efficiency of two-step scheme high and be lost low.
Another embodiment of this utility model additionally provides another LED drive circuit, as it is shown in figure 1,
Including: steady flow unit 101, DC/DC converter unit 102, feedback signal acquiring unit 103, feedback letter
Number processing unit 104 and DC/DC control unit 105；
The outfan series connection of steady flow unit 101 and DC/DC converter unit 102；
The input of feedback signal acquiring unit 103 is connected with the outfan of described steady flow unit；
The feedback end of DC/DC control unit 105 is connected with the outfan of feedback signal processing unit 104.
About feedback signal processing unit 104, optionally, as it is shown in figure 5, include: switch；
Described switch is connected to outfan and the DC/DC control unit 105 of feedback signal acquiring unit 103
Feedback end between；
The control end of described switch receives switching signal VK；
Switching signal VK is when the ripple of output voltage V1 of steady flow unit 101 is more than the first preset range
Time, control the switching signal of described switch OFF.
Illustrate as a example by DC/DC converter unit 102 is for buck converter unit, concrete, when surely
The ripple of the output voltage V1 of stream unit 101 exceedes described first preset range and causes described (Vref-VFB)
∈ [0, Vmax] relation is false, DC/DC converter unit 102 job insecurity time, open described in shutoff
Close, then feedback signal processing unit 104 does not has feedback signal VFB to be input to DC/DC control unit 105.
Now, as long as DC reference signal Vref is less than Vmax, i.e. can guarantee that described LED drive circuit is stable
Work；Therefore, feedback signal processing unit 104 is set to V1 ripple and exceedes described first preset range
Time, controlling switching signal Vk is that low level can turn off described switch, and DC/DC converter unit 102 is straight
Connect one DC voltage relevant to DC reference signal Vref of output.Though the most described LED drive circuit
So lose fall ripple effect, but ensure that circuit stability.
And when normal circuit operation, described switch closes, feedback signal VFB=Vp, it is directly inputted to
DC/DC control unit 105, DC/DC control unit 105 controls opening of DC/DC converter unit 102
Guan Guan, makes the output voltage V2 of DC/DC converter unit 102 have the output electricity with steady flow unit 101
The ripple that pressure V1 ripple is equal in magnitude, in opposite direction, it is achieved fall ripple function.
Or, feedback signal processing unit 104 as shown in Figure 6, including: switch, the first resistance R1 and
Second resistance R2；
Described switch is connected to outfan and the DC/DC control unit 105 of feedback signal acquiring unit 103
Feedback end between；
First resistance R1 and described switch in parallel；
One end ground connection of the second resistance R2, the other end of the second resistance R2 and DC/DC control unit 105
Feedback end be connected；
The control end of described switch receives switching signal VK；
Switching signal VK is when the ripple of output voltage V1 of steady flow unit 101 is more than the second preset range
Time, control the switching signal of described switch OFF.
When described LED drive circuit normally works, described switch closes, and VFB=Vp is equivalent to ripple
Signal Vp is directly injected into DC/DC control unit 105, the output voltage V2 of DC/DC converter unit 102
With the ripple opposite in phase of the output voltage V1 of steady flow unit 101, the ripple of described LED drive circuit
Will reduce and even be eliminated.
When the ripple of the output voltage V1 of steady flow unit 101 is too big, i.e. exceed described second preset range,
When causing circuit instability, described in switch off, ripple signal Vp through the first resistance R1 and second electricity
Obtaining feedback signal VFB after resistance R2 dividing potential drop, feedback signal VFB injects DC/DC control unit 105；
Now the ripple size of the output voltage V2 of DC/DC converter unit 102 cannot be with steady flow unit 101
The ripple of output voltage V1 is all offset, but also can offset a part, drives for whole described LED
For galvanic electricity road, ripple is also reduction of, and circuit stability.
Again or, feedback signal processing unit 104 as it is shown in fig. 7, comprises: clamp circuit；
Described clamp circuit and feedback signal acquiring unit 103 be parallel to the outfan of steady flow unit 101 with
Between the feedback end of DC/DC control unit 105；
Described clamp circuit is when the ripple of output voltage V1 of steady flow unit 101 is more than the 3rd preset range
Time, obtain the clamp circuit of feedback signal VFB after ripple signal Vp is carried out clamper.
Feedback signal processing unit 104 is clamp circuit, can obtain after ripple signal Vp is carried out clamper
VFB；When described LED drive circuit normally works, ripple signal Vp is less than the pincers of described clamp circuit
Position voltage, the output ripple of the output voltage V2 of DC/DC converter unit 102 and steady flow unit 101
Output voltage V1 opposite in phase；During described LED drive circuit instability, clamp voltage is to ripple signal
Vp obtains feedback signal VFB after carrying out clamper, feedback signal VFB after clamper can guarantee that described LED
Drive circuit steady operation.
Preferably, in the embodiment shown in Fig. 5 to Fig. 7, DC/DC control unit 105 includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is DC/DC control unit
The reference edge of 105, receives described DC reference signal, and another input of described subtractor is DC/DC
The feedback end of control unit 105, receives described feedback signal；The outfan of described subtractor and described the
One input of one integrated transporting discharging is connected；Another input of described first integrated transporting discharging is DC/DC
The sampling end of control unit 105, receives described sampled signal；
Or, DC/DC control unit 105 includes: adder and the second integrated transporting discharging；Described adder
The feedback end that an input is DC/DC control unit 105, receive described feedback signal；Described add
The sampling end that another input is DC/DC control unit 105 of musical instruments used in a Buddhist or Taoist mass, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
The reference edge that another input is DC/DC control unit 105 of amplifier, receives described DC reference letter
Number.
Or, as shown in Figure 8, the outfan of feedback signal acquiring unit 103 processes with feedback signal
The input of unit 104 is connected；
DC/DC control unit 105 also includes the ripple end receiving described ripple signal, described ripple end with
The outfan of feedback signal acquiring unit 103 is connected；
Feedback signal processing unit 104 is when the ripple of output voltage V1 of steady flow unit 101 is more than the 4th
During preset range, feedback signal VFB of output controls DC/DC by DC/DC control unit 105 and becomes
Change the feedback signal processing unit that output voltage is zero of unit 102.
Feedback signal acquiring unit 103 obtains the AC compounent of the output voltage V1 of steady flow unit 101, i.e.
Ripple signal Vp, ripple signal Vp can be directly inputted to the ripple end of DC/DC control unit 105,
When described LED drive circuit normally works, after superposing with sampled signal VS again with DC reference signal Vref
Relatively obtain control signal VC, or sampled signal VS compares with (Vref-Vp) and obtains control signal
VC, makes output ripple and the steady flow unit 101 of the output voltage V2 of DC/DC converter unit 102
Output voltage V1 opposite in phase, described LED drive circuit can play the effect reducing ripple.
And when the output voltage V1 ripple of steady flow unit 101 is very big, when i.e. ripple signal Vp peak value is the biggest,
For preventing described LED drive circuit unstable, feedback signal processing unit 104 output feedback signal VFB
Feedback end to DC/DC control unit 105 so that DC/DC control unit 105 exports a control
Idle control signal VC of DC/DC converter unit 102, controls the defeated of DC/DC converter unit 102
Going out voltage is zero.
Preferably, in the embodiment shown in fig. 8, DC/DC control unit 105 includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is DC/DC control unit
The reference edge of 105, receives described DC reference signal, and another input of described subtractor is DC/DC
The ripple end of control unit 105, receives described ripple signal；The outfan of described subtractor and described the
One input of one integrated transporting discharging is connected；Another input of described first integrated transporting discharging is DC/DC
The sampling end of control unit 105, receives described sampled signal；
Or, described DC/DC control unit includes: adder and the second integrated transporting discharging；Described adder
The ripple end that an input is DC/DC control unit 105, receive described ripple signal；Described add
The sampling end that another input is DC/DC control unit 105 of musical instruments used in a Buddhist or Taoist mass, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
The reference edge that another input is DC/DC control unit 105 of amplifier, receives described DC reference letter
Number.
What deserves to be explained is, the first preset range described in the present embodiment, the second preset range, the 3rd
Preset range and the 4th preset range, be not specifically limited herein, and its concrete span may be identical,
Being likely to each other, be for normally working so that DC/DC converter unit 102, protection is described
LED drive circuit working stability, can be depending on its concrete applied environment, all at the protection model of the application
In enclosing.
Owing to ripple and the temperature of LED drive circuit are closely bound up, when temperature reduces, output filter capacitor
ESR increase, output ripple will increase.In another embodiment the most of the present utility model, feedback letter
Number processing unit 104 can include temperature detection bleeder circuit, in concrete application, described temperature
Detection bleeder circuit is the bleeder circuit relevant with temperature, and the input of described temperature detection bleeder circuit is even
Connect feedback signal acquiring unit and obtain ripple signal Vp, and ripple signal Vp is entered according to the difference of temperature
After the dividing potential drop of row different proportion, output is to the feedback end of described DC/DC control unit: concrete, temperature is the highest,
Described intrinsic standoff ratio is the highest；Temperature is the lowest, and described intrinsic standoff ratio is the lowest.This is because during low temperature, ripple signal
Vp is very big, if intrinsic standoff ratio is very big, then causes feedback signal VFB the biggest, and VFB very conference causes institute
State DC/DC converter unit job insecurity.Therefore, during in order to ensure low temperature, circuit stability works, suitable
When sacrificing fall ripple effect to ensure circuit stability and work efficiency.
It addition, optional, described feedback signal acquiring unit includes: for obtaining the output of steady flow unit
The block isolating circuit of the AC compounent of voltage；The input of described block isolating circuit is that described feedback signal obtains list
The input of unit, the outfan of described block isolating circuit is the outfan of described feedback signal acquiring unit.
Being illustrated in figure 7 a kind of example, certainly, described feedback signal acquiring unit includes that block isolating circuit can
To be applied to the arbitrary shown LED drive circuit of Fig. 1, Fig. 5 to Fig. 8.
Optionally, described DC/DC converter unit is buck converter unit；Described DC/DC converter unit
As it is shown in fig. 7, comprises: second switch pipe K2, the second diode D2, the second electric capacity C2 and the first electricity
Sense L1；Wherein:
One end of one end of second switch pipe K2 and the first inductance L1 and the anode phase of the second diode D2
Even；
The other end of the first inductance L1 is an input of described DC/DC converter unit；
The other end of second switch pipe K2 and one end of the second electric capacity C2 are connected, and junction point is described
Another input of DC/DC converter unit；
The negative electrode of the second diode D2 and the other end of the second electric capacity C2 are connected；
The two ends of the second electric capacity C2 are respectively two outfans of described DC/DC converter unit.
Optionally, as arbitrary in Fig. 1, Fig. 5 to Fig. 8 shown in, DC/DC control unit 105 receive adopt
Sample signal VS obtains from the outfan of DC/DC converter unit 102.
It addition, the described LED drive circuit that the present embodiment provides can also be used in light adjusting circuit, adjust
The output voltage V1 of steady flow unit described in photoreduction process also can change.
In concrete actual application, steady flow unit 101, feedback signal acquiring unit 103 and DC/DC
The internal structure of control unit 105 can use existing circuit structure, repeats the most one by one, all
In the protection domain of the application.
In this utility model, each embodiment uses the mode gone forward one by one to describe, and each embodiment stresses
Being all the difference with other embodiments, between each embodiment, identical similar portion sees mutually.
For device disclosed in embodiment, owing to it corresponds to the method disclosed in Example, so describing
Fairly simple, relevant part sees method part and illustrates.
Below it is only preferred implementation of the present utility model, makes to skilled artisans appreciate that or real
Existing this utility model.To the multiple amendment of these embodiments will be to one skilled in the art aobvious and
Being clear to, generic principles defined herein can be without departing from spirit or scope of the present utility model
In the case of, realize in other embodiments.Therefore, this utility model is not intended to be limited to illustrated herein
These embodiments, and be to fit to consistent with principles disclosed herein and features of novelty the widest
Scope.
Claims (10)
1. a LED drive circuit, it is characterised in that including:
Control the steady flow unit of described LED drive circuit output stabling current value；
With the DC/DC converter unit that described steady flow unit drives LED load jointly, described steady flow unit
And the outfan series connection of described DC/DC converter unit；
Obtain the output ripple of described steady flow unit, and generate the anti-of ripple signal according to described output ripple
Feedback signal acquiring unit；Described output ripple includes: output current ripple and/or output voltage ripple；Institute
The outfan of the input and described steady flow unit of stating feedback signal acquiring unit is connected；
Receive described ripple signal, and export the anti-of associated feedback signal according to described ripple signal
Feedback signal processing unit；
Obtain described feedback signal and a sampling letter characterizing described DC/DC converter unit output voltage
Number, obtain or built-in DC reference signal, and according to described sampled signal, described feedback signal and described
DC reference signal generates the DC/DC control unit controlling signal to described DC/DC converter unit；Institute
Stating control signal is to control described DC/DC converter unit when described LED drive circuit working stability
The opposite in phase of output voltage ripple of output voltage ripple and described steady flow unit, drive at described LED
During the job insecurity of galvanic electricity road, the output voltage controlling described DC/DC converter unit is zero or controls institute
State DC/DC converter unit output voltage ripple reduce or be zero control signal；Described DC/DC is controlled
The feedback end of unit processed is connected with the outfan of described feedback signal processing unit.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Processing unit includes: switch；
Described switch is connected to the outfan of described feedback signal acquiring unit and described DC/DC control unit
Feedback end between；
The control end of described switch receives switching signal；
Described switching signal is when the ripple of output voltage of described steady flow unit is more than the first preset range
Time, control the switching signal of described switch OFF.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Processing unit includes: switch, the first resistance and the second resistance；
Described switch is connected to the outfan of described feedback signal acquiring unit and described DC/DC control unit
Feedback end between；
Described first resistance and described switch in parallel；
One end ground connection of described second resistance, the other end of described second resistance and described DC/DC control single
The feedback end of unit is connected；
The control end of described switch receives switching signal；
Described switching signal is when the ripple of output voltage of described steady flow unit is more than the second preset range
Time, control the switching signal of described switch OFF.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Processing unit includes: clamp circuit；
Described clamp circuit and described feedback signal acquiring unit be parallel to the outfan of described steady flow unit with
Between the feedback end of described DC/DC control unit；
Described clamp circuit is when the ripple of output voltage of described steady flow unit is more than the 3rd preset range
Time, obtain the clamp circuit of described feedback signal after described ripple signal is carried out clamper.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
The outfan of acquiring unit is connected with the input of described feedback signal processing unit；
Described DC/DC control unit also includes the ripple end receiving described ripple signal, described ripple end with
The outfan of described feedback signal acquiring unit is connected；
Described feedback signal processing unit is when the ripple of the output voltage of described steady flow unit is pre-more than the 4th
If during scope, the described feedback signal of output controls described DC/DC by described DC/DC control unit
The output voltage of converter unit is the feedback signal processing unit of zero.
6. according to the arbitrary described LED drive circuit of claim 1-4, it is characterised in that described
DC/DC control unit includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is that described DC/DC controls list
The reference edge of unit, receives described DC reference signal, and another input of described subtractor is described DC/DC
The feedback end of control unit, receives described feedback signal；The outfan of described subtractor and described first collection
The input becoming amplifier is connected；Another input of described first integrated transporting discharging is described DC/DC
The sampling end of control unit, receives described sampled signal；
Or, described DC/DC control unit includes: adder and the second integrated transporting discharging；Described adder
The feedback end that an input is described DC/DC control unit, receive described feedback signal；Described add
Another input of musical instruments used in a Buddhist or Taoist mass is the sampling end of described DC/DC control unit, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
Another input of amplifier is the reference edge of described DC/DC control unit, receives described DC reference letter
Number.
LED drive circuit the most according to claim 5, it is characterised in that described DC/DC is controlled
Unit processed includes:
Subtractor and the first integrated transporting discharging；One input of described subtractor is that described DC/DC controls list
The reference edge of unit, receives described DC reference signal, and another input of described subtractor is described DC/DC
The ripple end of control unit, receives described ripple signal；The outfan of described subtractor and described first collection
The input becoming amplifier is connected；Another input of described first integrated transporting discharging is described DC/DC
The sampling end of control unit, receives described sampled signal；
Or, described DC/DC control unit includes: adder and the second integrated transporting discharging；Described adder
The ripple end that an input is described DC/DC control unit, receive described ripple signal；Described add
Another input of musical instruments used in a Buddhist or Taoist mass is the sampling end of described DC/DC control unit, receives described sampled signal；
The outfan of described adder is connected with an input of described second integrated transporting discharging；Described second integrated
Another input of amplifier is the reference edge of described DC/DC control unit, receives described DC reference letter
Number.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Processing unit includes: the ratio controlling described feedback signal and described ripple signal vary with temperature and in the same direction
The temperature detection bleeder circuit of change；The input of described temperature detection bleeder circuit and described feedback signal
The outfan of acquiring unit is connected, and the outfan of described temperature detection bleeder circuit controls with described DC/DC
The feedback end of unit is connected.
LED drive circuit the most according to claim 1, it is characterised in that described feedback signal
Acquiring unit includes: for obtaining the block isolating circuit of the AC compounent of the output voltage of steady flow unit.
LED drive circuit the most according to claim 1, it is characterised in that described DC/DC
The described sampled signal that control unit receives obtains from the outfan of described DC/DC converter unit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620351760.1U CN205546101U (en) | 2016-04-22 | 2016-04-22 | Light -emitting diode (LED) driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620351760.1U CN205546101U (en) | 2016-04-22 | 2016-04-22 | Light -emitting diode (LED) driving circuit |
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|---|---|
| CN205546101U true CN205546101U (en) | 2016-08-31 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109362141A (en) * | 2018-09-13 | 2019-02-19 | 华域视觉科技(上海)有限公司 | OLED light source drive control circuit and OLED luminaire |
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2016
- 2016-04-22 CN CN201620351760.1U patent/CN205546101U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109362141A (en) * | 2018-09-13 | 2019-02-19 | 华域视觉科技(上海)有限公司 | OLED light source drive control circuit and OLED luminaire |
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