CN104270873B - LED driver, control method and control circuit - Google Patents
LED driver, control method and control circuit Download PDFInfo
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- CN104270873B CN104270873B CN201410584124.9A CN201410584124A CN104270873B CN 104270873 B CN104270873 B CN 104270873B CN 201410584124 A CN201410584124 A CN 201410584124A CN 104270873 B CN104270873 B CN 104270873B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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Abstract
The invention discloses an LED driver, a control method and a control circuit. When a dimming signal is indicated to be of a lowest value, the output voltage of the power level circuit of the LED driver is controlled to be smaller than a first threshold namely the lowest voltage which can power on LED load, and a dimming effect can be normally achieved; meanwhile, the output voltage is controlled to be greater than a second threshold, thereby ensuring that an auxiliary winding can provide sufficient voltage for supplying power to a dimmer normally. Therefore, when the dimmer directly or indirectly obtains power from the auxiliary winding, the problem that the dimmer cannot obtain power to work normally after a lowest dimming value of the dimmer is achieved is solved.
Description
Technical field
The present invention relates to Power Electronic Technique is and in particular to a kind of led driver, control method and control circuit.
Background technology
Light emitting diode (light-emitting diode, abbreviation led) illumination is increasingly becoming the main flow of lighting source
Technology.Tunable optical led device would generally change output current according to dim signal, thus realizing dimming function.If light modulation letter
Number produced by independent dimmer, need for dimmer powered, the supply voltage that dimmer needs is generally 3v-5v.
In the prior art, the power supply mode of dimmer mainly has two kinds:
The first power supply mode is from voltage bus power taking, and this mode is from an independent high voltage power supply power taking, needs
Corresponding voltage conversion device or stable-pressure device supply voltage is made to meet the needs of dimmer, this can increase and is manufactured into
This.The voltage being additionally, since voltage bus is higher, is therefore lost larger in transformation process.
Second power supply mode is directly or indirectly for dimmer powered by assists winding.Specifically, can be directly from auxiliary
Help the high-pressure side power taking of winding it is also possible to power taking at the supply node of assists winding power supply circuits, assists winding power supply circuits
Can using the voltage of assists winding between be connected in control circuit and power.Although second power supply mode has the low and low cost of loss
Advantage, assists winding provide voltage related to the output voltage of power stage circuit, when dim signal instruction minimum (generally right
Answer zero or close to zero output current so that led load brightness reach minimum) when, control circuit can quit work, and makes
The power switch obtaining power stage circuit is held off, and thus leads to output voltage to decline to a great extent.The decline of output voltage can lead to
Assists winding is supplied to the undertension of dimmer, and when re-starting light modulation, dimmer cannot normal work.
Content of the invention
In view of this, the present invention provides led driver, control method and control circuit, with solve dimmer directly or
Connect when assists winding power taking, dimmer is in light modulation to the problem that cannot obtain power supply after minimum.
In a first aspect, providing a kind of led driver, comprising:
Power stage circuit；
Assists winding, is coupled with the energy-storage travelling wave tube of described power stage circuit；
Dimmer, is directly or indirectly powered by described assists winding, exports dim signal；
Control circuit, in the flrst mode, controlling described power stage circuit output and light modulation letter according to dim signal
Number corresponding driving current, under the second mode, controls described power stage circuit output less than first threshold and to be more than the second threshold
Value output voltage；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the
One pattern；Described first threshold is the minimum output voltage value that led load can be made to light；Described Second Threshold is that dimmer is minimum
Output voltage values corresponding to supply voltage.
Preferably, described control circuit includes:
Constant-current control circuit, generates switch controlling signal according to described dim signal, and described switch controlling signal is used for controlling
Make described power stage circuit and export described driving current；
Pressure limiting circuit, for working under the second mode, when power stage circuit output voltage is more than rotection thresholds, output
Pressure limiting enables signal, and described rotection thresholds are less than described first threshold；
Logic circuit, when receiving described pressure limiting enable signal, does not export described switch controlling signal, is not receiving
When described pressure limiting enables signal, export described switch controlling signal.
Preferably, described control circuit includes:
Constant-current control circuit, generates first switch control signal according to described dim signal, and described first switch controls letter
Number it is used for controlling described power stage circuit to export described driving current；
Constant-voltage control circuit, generates second switch control signal, and described second switch control signal is used for controlling described work(
Rate level circuit output is less than first threshold and the output voltage more than Second Threshold；
Logic circuit, exports described first switch control signal to power stage circuit, in the flrst mode in second mode
Lower to power stage circuit export described second switch control signal.
Preferably, described control circuit includes:
Constant-current control circuit, in the flrst mode, generates first switch control signal according to dim signal, in second mode
Under, quit work, described first switch control signal is used for controlling described power stage circuit to export described driving current；
Constant-voltage control circuit, does not work in the flrst mode, under the second mode, generates second switch control signal, institute
State second switch control signal for controlling described power stage circuit output to be less than first threshold and the output more than Second Threshold
Voltage；
Logic circuit, exports described first switch control signal, otherwise when described first switch control signal is detected
Export described second switch control signal.
Second aspect, provides a kind of led driver control method, described led driver include power stage circuit, auxiliary around
Group and dimmer；Wherein, assists winding is coupled with the energy-storage travelling wave tube of described power stage circuit；Described dimmer by described auxiliary around
Group is directly or indirectly powered, and exports dim signal；
Methods described includes:
Work in first mode when described dim signal does not indicate minimum, otherwise, work in second mode；
In the flrst mode, described power stage circuit is controlled to export drive corresponding with dim signal according to described dim signal
Streaming current；
Under the second mode, control described power stage circuit output less than first threshold and electric more than the output of Second Threshold
Pressure；
Wherein, described first threshold is so that led loads the minimum output voltage value lighted；Described Second Threshold is light modulation
Output voltage values corresponding to the minimum supply voltage of device.
Preferably, described under the second mode, control the output of described power stage circuit less than first threshold and to be more than second
The output voltage of threshold value includes:
Under the second mode, when power stage circuit output voltage is more than and protects described first threshold, output switch does not control
Signal；
Wherein, described rotection thresholds are less than described first threshold.
Preferably, described under the second mode, control the output of described power stage circuit less than first threshold and to be more than second
The output voltage of threshold value includes:
Under the second mode, described power stage circuit is controlled by the switch controlling signal that constant-voltage control circuit generates, make
Obtain described output voltage to be less than first threshold and be more than Second Threshold.
The third aspect, provides a kind of control circuit, and for controlling led driver, described control circuit includes:
Constant-current control circuit, generates switch controlling signal according to dim signal, and described switch controlling signal is used for controlling institute
State power stage circuit and export described driving current；
Pressure limiting circuit, for working under the second mode, when power stage circuit output voltage is more than rotection thresholds, output
Pressure limiting enables signal, and described rotection thresholds are less than described first threshold；
Logic circuit, when receiving described pressure limiting enable signal, does not export described switch controlling signal, is not receiving
When described pressure limiting enables signal, export described switch controlling signal；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the
One pattern；Described first threshold is the minimum voltage that led load can be made to light；Described Second Threshold is dimmer minimum power supply electricity
The corresponding output voltage values of pressure.
Fourth aspect, provides a kind of control circuit, and for controlling led driver, described control circuit includes:
Constant-current control circuit, generates first switch control signal according to dim signal, and described first switch control signal is used
Export driving current corresponding with dim signal in controlling described power stage circuit；
Constant-voltage control circuit, generates second switch control signal, and described second switch control signal is used for controlling described work(
Rate level circuit output is less than first threshold and the output voltage more than Second Threshold；
Logic circuit, exports described first switch control signal in the flrst mode, exports described under the second mode
Two switch controlling signals；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the
One pattern；Described first threshold is the minimum voltage that led load can be made to light；Described Second Threshold is dimmer minimum power supply electricity
The corresponding output voltage values of pressure.
5th aspect, provides a kind of control circuit, and for controlling led driver, described control circuit includes:
Constant-current control circuit, in the flrst mode, generates first switch control signal according to dim signal, in second mode
Under quit work, described first switch control signal is used for controlling described power stage circuit to export driving corresponding with dim signal
Electric current；
Constant-voltage control circuit, quits work in the flrst mode, under the second mode, generates second switch control signal,
Described second switch control signal is used for controlling described power stage circuit output less than first threshold and defeated more than Second Threshold
Go out voltage；
Logic circuit, exports described first switch control signal, otherwise when described first switch control signal is detected
Export described second switch control signal；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the
One pattern；Described first threshold is the minimum voltage that led load can be made to light；Described Second Threshold is dimmer minimum power supply electricity
The corresponding output voltage values of pressure.
By when described dim signal is designated as minimum, controlling the output electricity of the power stage circuit making led driver
Pressure is less than first threshold, that is, enabling led to load the minimum voltage that can light so that dimming effect is normally realized；Meanwhile,
Output voltage is made to be more than Second Threshold it is ensured that assists winding provides enough voltage normally to supply for dimmer by controlling
Electricity.Thus, it is possible to solve dimmer directly or indirectly when assists winding power taking, dimmer is in light modulation to cannot obtain after minimum
The problem of power supply normal work.
Brief description
By the description to the embodiment of the present invention referring to the drawings, the above-mentioned and other purpose of the present invention, feature and
Advantage will be apparent from, in the accompanying drawings:
Fig. 1 is the circuit diagram of the led driver of the embodiment of the present invention；
Fig. 2 is the circuit block diagram of the control circuit of one embodiment of the invention；
Fig. 3 is the circuit block diagram of the control circuit of another embodiment of the present invention；
Fig. 4 is the circuit block diagram of the control circuit of another embodiment of the present invention；
Fig. 5 is the flow chart of the control method of led driver of the embodiment of the present invention.
Specific embodiment
Below based on embodiment, present invention is described, but the present invention is not restricted to these embodiments.Under
Literary composition in the detailed description of the present invention, detailed describes some specific detail sections.Do not have for a person skilled in the art
The description of these detail sections can also understand the present invention completely.In order to avoid obscuring the essence of the present invention, known method, mistake
Journey, flow process, element and circuit do not describe in detail.
Additionally, it should be understood by one skilled in the art that provided herein accompanying drawing be provided to descriptive purpose, and
Accompanying drawing is not necessarily drawn to scale.
It will also be appreciated that in the following description, " circuit " refers to be passed through electrically by least one element or electronic circuit
Connect or the galvanic circle that connects and composes of electromagnetism." connect when claiming element or another element of circuit " being connected to " or title element/circuit
" between two nodes when, it can directly be coupled or be connected to another element or there may be intermediary element, element it
Between connection can be physically, in logic or its combination.On the contrary, when claiming element " being directly coupled to " or " directly connect
Be connected to " another element when it is meant that there is not intermediary element in both.
Unless the context clearly requires otherwise, otherwise entire disclosure is similar with " inclusion " in claims, "comprising" etc.
Word should be construed to the implication comprising rather than exclusive or exhaustive implication；That is, being containing of " including but not limited to "
Justice.
In describing the invention it is to be understood that term " first ", " second " etc. are only used for describing purpose, and not
It is understood that as indicating or implying relative importance.Additionally, in describing the invention, unless otherwise stated, the implication of " multiple "
It is two or more.
Fig. 1 is the circuit diagram of the led drive circuit of the embodiment of the present invention.As shown in figure 1, the led of the present embodiment drives
Dynamic device 10 includes power stage circuit 11, assists winding 12, dimmer 13 and control circuit 14.
In FIG, power stage circuit 11 sampling reverse exciting topological, it includes primary side winding np, vice-side winding ns, power are opened
Close q1, commutation diode d1 and filter capacitor co.
Primary side winding np one end connects voltage bus receives input supply voltage vs, the other end is connected with power switch q1.
Voltage bus are to primary side winding np input DC power voltage vs.Primary side winding np and vice-side winding ns constitute power stage circuit 11
Energy-storage travelling wave tube.
In FIG, power switch q1 adopts metal oxide semiconductor transistor (mosfet), certainly, art technology
Personnel are appreciated that power switch q1 can also adopt other controllable semiconductor switches.
Commutation diode d1 is connected between one end of vice-side winding ns and the outfan o of power stage circuit 11, filtered electrical
Hold coIt is connected between the outfan o of power stage circuit 11 and the reference edge of secondary circuit.The other end of vice-side winding ns also with
The reference edge of secondary circuit connects.
The electric current flowing through primary side winding can be controlled by the turn-on and turn-off controlling power switch q1, it is by energy transmission
To vice-side winding ns so that power stage circuit exports satisfactory voltage or electric current.
Easy to understand, the power stage circuit of the led drive circuit of the present embodiment can also adopt other types of, can be with coupling
Close the DC-DC converter topology of assists winding, for example, positive activation type topology.
In FIG, the driving port drv of control circuit 14, to the grid output switch control signal of power switch q1, is controlled
The turn-on and turn-off of power switch q1 processed.Driving between port drv and the grid of power switch q1, can connect as needed
Drive resistance r5.
Meanwhile, sampling resistor r6 is connected between source electrode and the earth terminal of power switch q1, and its both end voltage is as electric current
Feedback signal viIt is input to the current feedback port isen of control circuit 14.Easy to understand, so that control circuit 14 obtains
The relevant information of output current, it would however also be possible to employ other components and circuit structure are realizing output current relevant information
Feedback.
Energy-storage travelling wave tube (namely the change that primary side winding np and vice-side winding ns are constituted of assists winding 12 and power stage circuit 11
Depressor) electromagnetic coupled.Thus, assists winding 12 can produce faradic current, exports the voltage related to output voltage.
Based on this characteristic, assists winding 12 may be used for control circuit and provides feedback voltage vfb.As shown in figure 1, auxiliary
Winding 12 first end connects resistor voltage divider circuit, and the second end is connected to earth terminal.In resistor voltage divider circuit, resistance r3 and resistance
R4 is connected in series between first end and the earth terminal of assists winding 12, and the voltage of both connected ends is as feedback voltage vfbInput
Voltage Feedback port vsen to control circuit.
Meanwhile, assists winding 12 can be combined with that peripheral circuit is control circuit or other circuit is powered.As shown in figure 1,
Start resistance r1 to be connected between voltage bus and feeder ear s, start-up capacitance c1 is connected between feeder ear s and earth terminal, two
Pole pipe d2 and resistance r2 are connected in series between the first end of assists winding 12 and feeder ear s.Feeder ear s and the confession of control circuit
Electric port vin connects, for its power supply.
Start resistance r1 and open the initial stage to start-up capacitance c1 charging so that start-up capacitance c1 both end voltage rises in circuit,
Power for control circuit 14.After circuit start, flow through the faradic current of assists winding 12 after diode d2 rectification in electricity
A voltage can be control circuit or other circuit is powered so that feeder ear s has to form pressure drop on resistance r2.
The supply port of dimmer 13 is connected with the first end of assists winding 12 or is connected (connection line with feeder ear s
It is represented by dashed line in FIG).Thus, assists winding 12 can directly or indirectly be powered for dimmer 13.Dimmer 13 is to control
The light modulation port pwm output dim signal v of circuit 14dim.In the present embodiment, dim signal vdimCan be a pulsewidth modulation letter
Number, it is input to the dim signal input port pwm of control circuit 14.Control circuit 14 is according to dim signal vdimAverage electricity
Pressure or dutycycle are adjusting driving current ioSo that drive circuit ioWith dim signal vdimCorresponding.In dim signal vdimAverage
When voltage is larger, control circuit 14 controls power stage circuit 11 to export larger driving current so that led load brightness is larger,
In dim signal vdimAverage voltage less when, control circuit 14 control power stage circuit 11 export less driving current, make
Obtain led load brightness less, hereby it is achieved that light modulation.
Certainly, it should be readily apparent to one skilled in the art that dim signal vdimCan also take other form.
In the present embodiment, control circuit 14 can be in two MODE of operation.In dim signal vdimWhen indicating minimum
(that is, instruction zero or close to zero output current so that led load brightness reach minimum when, now, dim signal vdim's
Average voltage can be between 0-5v), control circuit 14 works in second mode, otherwise, works in first mode.In the first mould
Under formula, control circuit 14 is according to dim signal vdimControl power stage circuit 11 output and dim signal vdimCorresponding driving current
io；Under the second mode, control circuit 14 controls power stage circuit 11 to make output voltage voLess than first threshold and more than second
Threshold value.
Wherein, described first threshold is so that led loads the minimum voltage value lighted, and described Second Threshold is to make auxiliary
Winding can be normally the minimum voltage of dimmer powered, that is, the output voltage values corresponding to the minimum supply voltage of dimmer.
By when described dim signal is designated as minimum, controlling the output electricity of the power stage circuit making led driver
Pressure is less than first threshold, that is, enabling led to load the minimum voltage that can light so that dimming effect is normally realized；Meanwhile,
Output voltage is made to be more than Second Threshold it is ensured that assists winding provides enough voltage normally to supply for dimmer by controlling
Electricity.Thus, it is possible to solve dimmer directly or indirectly when assists winding power taking, dimmer is in light modulation to cannot obtain after minimum
The problem of power supply normal work.
Fig. 2 is the circuit block diagram of the control circuit of one embodiment of the invention.As shown in Fig. 2 in this embodiment, control
Circuit 14 includes constant-current control circuit 141, pressure limiting circuit 142 and logic circuit 143.Easy to understand, so that control circuit
Normal work, control circuit 14 generally will also include other circuit unit such as power supply circuits being connected to supply port, and (in figure is not
Illustrate).
Constant-current control circuit 141 is connected with light modulation port pwm, Voltage Feedback port vsen and current feedback port isen,
Input dim signal vdim, voltage feedback signal vfbWith current feedback signal vi, it is according to dim signal vdimAnd feedback voltage
vfbWith current feedback signal viGenerate switch controlling signal.Switch controlling signal is used for controlling described power stage circuit output and adjusting
The corresponding driving current of optical signal.Wherein, dim signal vdimFor knowing corresponding desired output for constant-current control circuit 141
Driving current.Feedback voltage vfbWith current feedback signal viFor obtaining the shape of power stage circuit for constant-current control circuit 141
State, keeps stablizing of driving current.
Pressure limiting circuit 142 is connected with light modulation port pwm and Voltage Feedback port vsen, inputs dim signal vdimAnd voltage
Feedback signal vfb.Pressure limiting circuit 142 is used for working under the second mode, in power stage circuit 11 output voltage voMore than protection threshold
During value, output pressure limiting enables signal, starts pressure-limiting function.Pressure limiting circuit 142 is according to dim signal vdimDetermine working condition.?
Dim signal vdimWhen not indicating minimum, pressure limiting circuit 142 does not work.In dim signal vdimWhen indicating minimum, pressure limiting circuit 142
Start and work.Wherein, rotection thresholds are less than first threshold, that is, under the second mode, do not rise to and can make in output voltage
Led load when lighting, pressure limiting circuit 142 will export pressure limiting and enable signal.
Logic circuit 143, when receiving described pressure limiting enable signal, does not export described switch controlling signal, is not receiving
During to pressure limiting enable signal, export described switch controlling signal.
Control circuit shown in Fig. 2 can be applicable in the led driver shown in Fig. 1.In dim signal vdimInstruction is not
When low, pressure limiting circuit 142 does not work.Now, the normal output switch control signal of logic circuit 143, controls power stage circuit 11
Output and dim signal vdimCorresponding driving current is so that led loads normal luminous.
In dim signal vdimWhen indicating minimum, pressure limiting circuit 142 works in second mode, and its rotection thresholds is less than second
Threshold value.Now, output voltage is generally also greater than Second Threshold, that is, being more than rotection thresholds, therefore, pressure limiting circuit 142 output limit
Pressure enables signal so that logic circuit 143 not output switch control signal, and power switch q1 is turned off, and led load stops luminous
(namely modulated light is extremely minimum), control circuit 14 quits work simultaneously.Output voltage continuous decrease, drops to little in output voltage
After rotection thresholds, pressure limiting circuit 142 stops output pressure limiting and enables signal.Meanwhile, voltage bus are passed through to start resistance r1 to opening
Dynamic condenser c1 charges and so that the voltage of feeder ear s is increased, and constitutes and control circuit 14 is recovered after postponing a period of time
Work.After control circuit 14 is resumed work, logic circuit output switch control signal makes the output voltage of power stage circuit 11
Rise.When being raised on the output voltage more than rotection thresholds, output protection enables so that control circuit pressure limiting circuit 142 again
14 quit work.
Thus, in dim signal vdimRemain instruction minimum period, control circuit 14 repeats above-mentioned startup, stops, restarting
Process so that power stage circuit 11 output voltage be less than first threshold, thereby may be ensured that led load during this period not by
Light, output voltage can be remained above Second Threshold again simultaneously, thus voltage can be provided in assists winding 12 direct or indirect
Power for dimmer 13, it is to avoid dimmer cisco unity malfunction.
Fig. 3 is the circuit block diagram of the control circuit of another embodiment of the present invention.As shown in figure 3, control circuit 14 includes
Constant-current control circuit 141 ', constant-voltage control circuit 142 ' and logic circuit 143 '.
Constant-current control circuit 141 ' is connected with light modulation port pwm, Voltage Feedback port vsen and current feedback port isen,
Input dim signal vdim, voltage feedback signal vfbWith current feedback signal vi, it is according to dim signal and feedback voltage vfbWith
Current feedback signal viGenerate first switch control signal, first switch control signal is used for controlling power stage circuit 11 output to adjust
Optical signal vdimCorresponding driving current.Wherein, feedback voltage vfbWith current feedback signal viFor for constant-current control circuit 141 '
Obtain the state of power stage circuit, keep stablizing of driving current.
Constant-voltage control circuit 142 ' is connected with Voltage Feedback port vsen, and input voltage feeds back signal vfb, generate second and open
Close control signal, second switch control signal is used for controlling power stage circuit 11 output less than first threshold and to be more than Second Threshold
Output voltage.
Logic circuit 143 ' is connected with light modulation port pwm, inputs dim signal vdim, also input first switch control simultaneously
Signal and second switch control signal.Logic circuit 143 ' may operate in different patterns.In dim signal vdimDo not indicate
When low, logic circuit 143 ' works in first mode, exports described first switch control signal to power stage circuit 11；In light modulation
Signal vdimWhen indicating minimum, logic circuit 143 ' works under second mode, exports described second switch to power stage circuit 11
Control signal.
Thus, in dim signal vdimRemain instruction minimum period, control circuit 14 does not quit work, but switching
For Isobarically Control pattern, control power stage circuit 11 output less than first threshold and be more than the output voltage of Second Threshold.One side
Face ensure that led load can not obtain higher than the voltage of first threshold and light, on the other hand ensure that can in assists winding 12
To provide voltage directly or indirectly as dimmer powered, it is to avoid dimmer cisco unity malfunction.
Fig. 4 is the circuit block diagram of the control circuit of another embodiment of the present invention.As shown in figure 4, control circuit 14 includes
Constant-current control circuit 141 ", constant-voltage control circuit 142 " and logic circuit 143 ".
Constant-current control circuit 141 " is connected with light modulation port pwm, Voltage Feedback port vsen and current feedback port isen,
Input dim signal vdim, voltage feedback signal vfbWith current feedback signal vi.In dim signal vdimWhen not indicating minimum, constant current
Control circuit 141 " is according to dim signal and feedback voltage vfbWith current feedback signal viGenerate first switch control signal, the
One switch controlling signal is used for controlling the described power stage circuit output corresponding driving current of dim signal；In dim signal vdim
When indicating minimum, constant-current control circuit 141 " quit work, do not export first switch control signal.
Constant-voltage control circuit 142 " is connected with light modulation port pwm and Voltage Feedback port vsen, inputs dim signal vdimWith
Voltage feedback signal vfb.In the present embodiment, constant-voltage control circuit 142 " are according to dim signal vdimWork in different work shapes
State.In dim signal vdimWhen not indicating minimum, constant-voltage control circuit 142 " quit work；In dim signal vdimInstruction is minimum
When, constant-voltage control circuit 142 " generate second switch control signal, second switch control signal is used for controlling power stage circuit 11
Output is less than first threshold and the output voltage more than Second Threshold.
Logic circuit 143 " exports first switch control signal when first switch control signal is detected, otherwise output the
Two switch controlling signals.
Thus, in dim signal vdimRemain instruction minimum period, control circuit 14 does not quit work, but switching
For Isobarically Control pattern, control power stage circuit 11 output less than first threshold and be more than the output voltage of Second Threshold.One side
Face ensure that led load can not obtain higher than the voltage of first threshold and light, on the other hand ensure that can in assists winding 12
To provide voltage directly or indirectly as dimmer powered, it is to avoid dimmer cisco unity malfunction.
Easy to understand, above-described embodiment only describes the electric circuit element related to the technical problem being solved, according to existing
Technology, can also include power supply circuits in control circuit 14 and be connected to logic circuit and drive the driving electricity between port
Road, to provide necessary power supply and signal conditioning functions.
Fig. 5 is the method flow diagram of the led driver control method of the embodiment of the present invention, and it is used for controlling shown in Fig. 1
Led driver.Methods described includes:
Step 510, work in first mode when described dim signal does not indicate minimum, otherwise, work in second mode.
Step 520, in the flrst mode, controls described power stage circuit output corresponding with dim signal according to dim signal
Driving current.
Step 530, under the second mode, controls and makes the output voltage of described power stage circuit be less than first threshold and big
In Second Threshold.
Wherein, described first threshold is so that led loads the minimum voltage lighted.Described Second Threshold is that dimmer is minimum
Output voltage values corresponding to supply voltage.
In a preferred embodiment, under the second mode, not defeated when power stage circuit output voltage is more than rotection thresholds
Go out switch controlling signal；
Wherein, described rotection thresholds are less than described Second Threshold.
In another optimal way, under the second mode, the switch controlling signal control being generated by constant-voltage control circuit
Make described power stage circuit so that described output voltage is less than first threshold and is more than Second Threshold.
By when described dim signal is designated as minimum, controlling the output electricity of the power stage circuit making led driver
Pressure is less than first threshold, that is, enabling led to load the minimum voltage that can light so that dimming effect is normally realized；Meanwhile,
Output voltage is made to be more than Second Threshold it is ensured that assists winding provides enough voltage normally to supply for dimmer by controlling
Electricity.Thus, it is possible to solve dimmer directly or indirectly when assists winding power taking, dimmer is in light modulation to cannot obtain after minimum
The problem of power supply normal work.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for those skilled in the art
For, the present invention can have various change and change.All any modifications made within spirit and principles of the present invention, equivalent
Replace, improve etc., should be included within the scope of the present invention.
Claims (10)
1. a kind of led driver, comprising:
Power stage circuit；
Assists winding, is coupled with the energy-storage travelling wave tube of described power stage circuit；
Dimmer, is directly or indirectly powered by described assists winding, exports dim signal；
Control circuit, in the flrst mode, controlling described power stage circuit output and dim signal pair according to dim signal
The driving current answered, under the second mode, controls described power stage circuit output less than first threshold and more than Second Threshold
Output voltage；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the first mould
Formula；Described first threshold is the minimum output voltage value that led load can be made to light；Described Second Threshold is the minimum power supply of dimmer
Output voltage values corresponding to voltage.
2. led driver according to claim 1 is it is characterised in that described control circuit includes:
Constant-current control circuit, generates switch controlling signal according to described dim signal, and described switch controlling signal is used for controlling institute
State power stage circuit and export described driving current；
Pressure limiting circuit, for working under the second mode, when power stage circuit output voltage is more than rotection thresholds, exports pressure limiting
Enable signal, described rotection thresholds are less than described first threshold；
Logic circuit, when receiving described pressure limiting enable signal, does not export described switch controlling signal, described not receiving
When pressure limiting enables signal, export described switch controlling signal.
3. led driver according to claim 1 is it is characterised in that described control circuit includes:
Constant-current control circuit, generates first switch control signal according to described dim signal, and described first switch control signal is used
Export described driving current in controlling described power stage circuit；
Constant-voltage control circuit, generates second switch control signal, and described second switch control signal is used for controlling described power stage
Circuit output is less than first threshold and the output voltage more than Second Threshold；
Logic circuit, in the flrst mode to power stage circuit export described first switch control signal, under the second mode to
Power stage circuit exports described second switch control signal.
4. led driver according to claim 1 is it is characterised in that described control circuit includes:
Constant-current control circuit, in the flrst mode, generates first switch control signal according to dim signal, under the second mode,
Quit work, described first switch control signal is used for controlling described power stage circuit to export described driving current；
Constant-voltage control circuit, does not work in the flrst mode, under the second mode, generates second switch control signal, and described the
Two switch controlling signals are used for the output voltage controlling described power stage circuit output less than first threshold and being more than Second Threshold；
Logic circuit, exports described first switch control signal, otherwise exports when described first switch control signal is detected
Described second switch control signal.
5. a kind of control method of led driver, described led driver includes power stage circuit, assists winding and dimmer；Its
In, assists winding is coupled with the energy-storage travelling wave tube of described power stage circuit；Described dimmer is direct or indirect by described assists winding
Power supply, exports dim signal；
Methods described includes:
Work in first mode when described dim signal does not indicate minimum, otherwise, work in second mode；
In the flrst mode, described power stage circuit output driving electricity corresponding with dim signal is controlled according to described dim signal
Stream；
Under the second mode, control described power stage circuit output less than first threshold and be more than the output voltage of Second Threshold；
Wherein, described first threshold is so that led loads the minimum output voltage value lighted；Described Second Threshold is for dimmer
Output voltage values corresponding to low suppling voltage.
6. led driver control method according to claim 5 it is characterised in that described under the second mode, control institute
State power stage circuit output to include less than first threshold and more than the output voltage of Second Threshold:
Under the second mode, the not output switch control signal when power stage circuit output voltage is more than rotection thresholds；
Wherein, described rotection thresholds are less than described first threshold.
7. led driver control method according to claim 5 it is characterised in that described under the second mode, control institute
State power stage circuit output to include less than first threshold and more than the output voltage of Second Threshold:
Under the second mode, the switch controlling signal being generated by constant-voltage control circuit controls described power stage circuit so that institute
State output voltage to be less than first threshold and be more than Second Threshold.
8. a kind of control circuit, for controlling the power stage circuit of led driver, described control circuit includes:
Constant-current control circuit, generates switch controlling signal according to dim signal, and described switch controlling signal is used for controlling described work(
Rate level circuit output driving current；
Pressure limiting circuit, for working under the second mode, when power stage circuit output voltage is more than rotection thresholds, exports pressure limiting
Enable signal, described rotection thresholds are less than first threshold；
Logic circuit, when receiving described pressure limiting enable signal, does not export described switch controlling signal, described not receiving
When pressure limiting enables signal, export described switch controlling signal；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the first mould
Formula；Described first threshold is the minimum voltage that led load can be made to light.
9. a kind of control circuit, for controlling the power stage circuit of led driver, described control circuit includes:
Constant-current control circuit, generates first switch control signal according to dim signal, and described first switch control signal is used for controlling
Make described power stage circuit and export driving current corresponding with dim signal；
Constant-voltage control circuit, generates second switch control signal, and described second switch control signal is used for controlling described power stage
Circuit output is less than first threshold and the output voltage more than Second Threshold；
Logic circuit, exports described first switch control signal in the flrst mode, exports described second under the second mode and opens
Close control signal；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the first mould
Formula；Described first threshold is the minimum voltage that led load can be made to light；Described Second Threshold is dimmer minimum supply voltage institute
Corresponding output voltage values.
10. a kind of control circuit, for controlling the power stage circuit of led driver, described control circuit includes:
Constant-current control circuit, in the flrst mode, generates first switch control signal according to dim signal, stops under the second mode
Only work, described first switch control signal is used for controlling described power stage circuit output driving electricity corresponding with dim signal
Stream；
Constant-voltage control circuit, quits work in the flrst mode, under the second mode, generates second switch control signal, described
Second switch control signal is used for controlling described power stage circuit output less than first threshold and electric more than the output of Second Threshold
Pressure；
Logic circuit, exports described first switch control signal, otherwise exports when described first switch control signal is detected
Described second switch control signal；
Wherein, described control circuit works in second mode when the instruction of described dim signal is minimum, otherwise, works in the first mould
Formula；Described first threshold is the minimum voltage that led load can be made to light；Described Second Threshold is dimmer minimum supply voltage institute
Corresponding output voltage values.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410584124.9A CN104270873B (en) | 2014-10-27 | 2014-10-27 | LED driver, control method and control circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410584124.9A CN104270873B (en) | 2014-10-27 | 2014-10-27 | LED driver, control method and control circuit |
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| CN104270873A CN104270873A (en) | 2015-01-07 |
| CN104270873B true CN104270873B (en) | 2017-02-01 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106162985B (en) * | 2016-06-30 | 2018-03-06 | 成都芯源系统有限公司 | L ED driver and driving method |
| CN113423156A (en) * | 2021-06-19 | 2021-09-21 | 浙江榆阳电子有限公司 | Low-dimming-rate quick start circuit of LED dimming power supply and start method thereof |
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|---|---|---|---|---|
| CN201541386U (en) * | 2009-10-20 | 2010-08-04 | 秦兵 | Remote-control and key dimming energy-saving lamp |
| CN102239742A (en) * | 2008-09-05 | 2011-11-09 | 埃尔多实验室控股有限公司 | Led based lighting application |
| CN202145692U (en) * | 2011-07-28 | 2012-02-15 | 林万炯 | LED flicker filter circuit |
| CN103440848A (en) * | 2013-09-02 | 2013-12-11 | 深圳市华星光电技术有限公司 | Backlight driving circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8183845B2 (en) * | 2008-11-24 | 2012-05-22 | Exelis, Inc. | Low voltage power supply |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102239742A (en) * | 2008-09-05 | 2011-11-09 | 埃尔多实验室控股有限公司 | Led based lighting application |
| CN201541386U (en) * | 2009-10-20 | 2010-08-04 | 秦兵 | Remote-control and key dimming energy-saving lamp |
| CN202145692U (en) * | 2011-07-28 | 2012-02-15 | 林万炯 | LED flicker filter circuit |
| CN103440848A (en) * | 2013-09-02 | 2013-12-11 | 深圳市华星光电技术有限公司 | Backlight driving circuit |
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