CN104470031A - Electronic device and control method capable of adjusting direct current flowing through element - Google Patents
Electronic device and control method capable of adjusting direct current flowing through element Download PDFInfo
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- CN104470031A CN104470031A CN201310421205.2A CN201310421205A CN104470031A CN 104470031 A CN104470031 A CN 104470031A CN 201310421205 A CN201310421205 A CN 201310421205A CN 104470031 A CN104470031 A CN 104470031A
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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 embodiment of the invention provides an electronic device and control method capable of adjusting direct current flowing through an element. The electronic device comprises an amplification circuit and a pulse width modulation generator; the amplification circuit is provided with a first input end which is coupled with a first voltage signal which represents the direct current flowing through the element, and a second input end which is coupled with a reference voltage; the amplification circuit is also provided with an output end which provides an output signal; the amplification circuit has a differential gain; the pulse width modulation generator provides a pulse width modulated signal according to the output signal and can define a switch-on time and a switch-off time to adjust the direct current; the differential gain is about zero at the closing time.
Description
Technical field
The present invention relates to control device and the control method of current driving element, particularly relate to relevant apparatus and the method that precisely can control the average driving current of current driving element.
Background technology
In order to more understand superiority of the present invention, first introduce a decompression converting circuit of the prior art (buck converter circuit) 100 at this, as shown in Figure 1.Decompression converting circuit 100 can be used in the backlight module (backlight module) of liquid crystal display, provides the backlight of certain brightness with light-emitting diode.In decompression converting circuit 100, an integrated circuit 102 controls power switch 104.Be serially connected in have between high power line VIN and ground power line GND a light-emitting diode string (LED string) 106, inductance 108, power switch 104, with current sense resistor RCS.Light-emitting diode string 106, by many light-emitting diodes, is forward serially connected.Discharge diode 110 is connected between high power line VIN and power switch 104.Filter capacitor 109 and light-emitting diode string (LED string) 106 are in parallel, and are used for making the drive current of light-emitting diode string 106 be unlikely to change excessive.
Controller 112 and gate drivers (gate driver) 114 is had in integrated circuit 102.The current detection signal V that controller 112 provides according to current sense resistor RCS
cS, produce pulse-width signal S
pWM.Gate drivers 114 is according to pulse-width signal S
pWMlogic level, appropriate voltage or current drive signal V are provided
g, carry out driving power switch 104.Fig. 2 shows an integrated circuit 102 of the prior art.Wherein, controller 112 includes set-reset flip-floop 116, clock generator 118, comparator 120, leading edge blanking device (leading edge blanking circuit) 122.
Clock generator 118 can periodically arrange set-reset flip-floop 116.When power switch 104 is unlocked at the beginning, pulse-width signal S
pWMenter the opening time (On time), leading edge blanking device (leading edge blanking circuit) 122 can cover current detection signal V
cSthe time of one very short, to avoid current detection signal V
cSnoise at the beginning have impact on whole control loop.Comparator 120 compares current detection signal V
cSwith reference voltage V
rEF-OLD.
Integrated circuit 102 in Fig. 2 can control current detection signal V
cSpeak value, make it approximate greatly reference voltage V
rEF-OLD.Fig. 3 shows the control result of Fig. 2, wherein, and current signal IL
1-OLDwith IL
2-OLDrepresent respectively, inductance 108 is respectively L
1with L
2time, flow through the electric current of inductance 108.Drive singal V
gduring " 1 " logically, power switch 104 conducting, is opening time (ON time), current signal IL
1-OLDwith IL
2-OLDall rise.As drive singal V
gduring " 0 " logically, power switch 104 is closed, and is shut-in time (OFF time), so current signal IL
1-OLDwith IL
2-OLDall decline.As shown in Figure 3, current signal IL
1-OLDwith IL
2-OLDpeak value all approximately maintain V
rEF-OLD/ R
cS, wherein R
cSfor the resistance value of current sense resistor RCS.The average current flowing through light-emitting diode string 106 is exactly the average current flowing through inductance 108.Can find from Fig. 3, when inductance 108 is respectively L
1with L
2time, flow through the average current of light-emitting diode string 106, be respectively different ILED
1-OLDwith ILED
2-OLD.Therefore, under the integrated circuit 102 of Fig. 2 controls, the average driving current of the light-emitting diode string 106 produced, will change along with inductance 108.In other words, the brightness that light-emitting diode string 106 produces, will along with the difference of inductance 108, instead of a fixed value.
Summary of the invention
One embodiment of the invention provide a kind of electronic installation that can adjust the direct current flowing through an element.This electronic installation includes an amplifying circuit and a PWM generator.This amplifying circuit has a first input end, couples one first voltage signal, and its representative flows through an electric current of this element, and one second input, couples a reference voltage.This amplifying circuit also has an output, provides an output signal.This amplifying circuit has a differential gain.This PWM generator, according to this output signal, provides a pulse-width signal, its definable one opening time and a shut-in time, adjusts this direct current.When this shut-in time, this differential gain is approximately 0.
One embodiment of the invention provide a kind of adjustment to flow through the control method of a direct current of an element: receive one first voltage signal, and its representative flows through an electric current of this element; One reference signal is provided; According to this first voltage signal and this reference signal, based on a differential gain, produce an output current signal; According to this output current signal, produce a pulse-width signal, to adjust this direct current, wherein, this pulse-width signal defines an opening time and a shut-in time; And, when this shut-in time, make this differential gain be approximately 0.
Accompanying drawing explanation
Fig. 1 is an existing decompression converting circuit.
Fig. 2 shows an existing integrated circuit, may be used for Fig. 1.
Fig. 3 is the control result of the integrated circuit of Fig. 2.
Fig. 4 shows the integrated circuit implemented according to the present invention.
Fig. 5 is the waveform of some signals in Fig. 4.
Fig. 6 shows Fig. 4 cover for the control result after Fig. 1.
Reference numeral explanation
100 decompression converting circuits
102 integrated circuits
104 power switchs
106 light-emitting diode strings
109 filter capacitors
108 inductance
110 discharge diodes
112 controllers
114 gate drivers
116 set-reset flip-floops
118 clock generators
120 comparators
122 leading edge blanking devices
200 integrated circuits
202 clock generators
203 PWM generator
204 amplifiers
206 comparators
208 adders
210 building-out capacitors
211 and door
212 computing transduction amplifiers
214 switches
GND ground power line
I
cOMcompensating current signal
IL
1, IL
2current signal
IL
1-OLD, IL
2-OLDcurrent signal
ILED
1-OLD, ILED
2-OLDthe average current of light-emitting diode string
RCS current sense resistor
SCLK clock signal
SDIM dim signal
S
pWMpulse-width signal
T
0, t
1, t
2time point
T
cYCcycle time
V
cOMcompensation voltage signal
V
cScurrent detection signal
V
gdrive singal
VIN height power line
V-
rAMPramp signal
V
rEFreference voltage
V
rEF-OLDreference voltage
V
sAWsawtooth waveforms
Embodiment
Fig. 4 shows an integrated circuit 200, in one embodiment, can replace the integrated circuit 102 in Fig. 1.In Fig. 4, with functionally same or analogous element in Fig. 2 of prior art, represent with identical symbol.
Integrated circuit 200 has PWM generator 203, amplifier 204 and leading edge blanking device 122.PWM generator 203 include clock generator 202, with door (And Gate) 211, set-reset flip-floop 116, building-out capacitor 210, comparator 206 and adder 208.
When dim signal SDIM is activation, namely during " 1 " in logic, clock generator 202 periodically sets set-reset flip-floop 116 with clock signal SCLK, so pulse-width signal SPWM periodically can enter the opening time (ON time), carried out the power switch 104 in conducting Fig. 1 by gate drivers 114.So, the electric current I L flowing through the inductance 108 in Fig. 1 starts to increase.Contrary, when dim signal SDIM is forbidden energy, namely during " 0 " in logic, block clock signal SCLK with door 211.Now, pulse-width signal S
pWMcan maintain the shut-in time (OFF time), power switch 104 is closed always.
The non-inverting input of amplifier 204 receives reference voltage V
rEF, reverse input end is by leading edge blanking device 122 received current detection signal V
cS.The output of amplifier 204 provides compensating current signal I
cOM(flowing out amplifier 204 to be just defined as), it is accumulated in the result on building-out capacitor 210, creates compensation voltage signal V
cOM.Computing transduction amplifier (operational transconductance amplifier, OTA) 212 and a switch 214 is included in amplifier 204.Switch 214 is controlled by pulse-width signal S
pWM.The differential transduction gain of computing transduction amplifier 212 is assumed to gm, that is I
cOM=gm* (V
rEF-V
cS).On the whole, when the opening time, switch 214 short circuit, the equivalent differential gain of amplifier 204 is gm, I
cOM-to building-out capacitor 210 discharge and recharge; When the shut-in time, switch 214 is opened a way, and the equivalent differential gain of amplifier 204 is approximately 0, I
cOM=0, building-out capacitor 210 holds the compensation voltage signal V observed instantly
cOM.
Comparator 206 compares compensation voltage signal V
cOMand ramp signal V-
rAMP.In the fig. 4 embodiment, ramp signal V-
rAMPapproximate greatly current detection signal V
cS-the sawtooth waveforms V provided with clock generator 202
sAWsum total.Sawtooth waveforms V
sAWwhen the opening time starts, can, from the definite value preset, start to rise.Sawtooth waveforms V
sAWadd, slope-compensation (slope compensation) can be provided, suppress subharmonic to shake the problem of (sub-harmonic oscillation).Once ramp signal V-
rAMPexceed compensation voltage signal V
cOM, comparator 206 can reset (reset) set-reset flip-floop 116, pulse-width signal S
pWMbecome " 0 " in logic, enter the shut-in time.
In another embodiment, ramp signal V-
rAMPcan be exactly current detection signal V
cS, namely do not carry out slope-compensation.In more another embodiment, ramp signal V-
rAMPcan be exactly sawtooth waveforms V
sAW, without any current detection signal V
cScomposition.
When stable state, compensation voltage signal V
cOMcan not along with clock signal S
cLKclock count and change.Because the equivalent differential gain of amplifier 204 is not only 0 when the opening time, so the circuit in Fig. 4, current detection signal V can be made
cS-mean value within the opening time, approximates greatly reference voltage V
rEF.
Fig. 5 is the waveform of some signals in Fig. 4.Please refer to Fig. 1 and Fig. 4.At this, assuming that the integrated circuit 200 of Fig. 4 instead of the integrated circuit 102 in Fig. 1, and in Fig. 1, decompression converting circuit 100 operates in continuous conduction mode (continuous conduction mode, CCM).Here so-called CCM, refers to that inductance 108 is in a switch periods, and complete discharge off, does not just enter another switch periods.In Fig. 5, the cycle time (cycle time) of each switch periods is TCYC.In one embodiment, cycle time, TCYC was a constant time constant.In other embodiments, TCYC can increase along with compensation voltage signal VCOM and reduce cycle time.
When each switch periods starts, just there is a short pulse, set-reset flip-floop 116 be set in clock signal SCLK.So, time point t0 in Figure 5, pulse-width signal S
pWMtransition is " 1 " in logic, and the opening time starts.Sawtooth waveforms V
sAWstart to increase from a preset value.
Within the opening time, because power switch 104 is conductings, the cross-pressure between high power line VIN to ground power line GND can drive the electric current of inductance 108, makes it start to increase.Therefore, current detection signal V
cSlinear rising.At time point t
0, current detection signal V
cSlower than reference voltage V
rEF.Therefore, compensating current signal I
cOMbuilding-out capacitor 210 is charged, compensation voltage signal V
cOMrise.
At time point t
1afterwards, current detection signal V
cSexceed reference voltage V
rEF, compensating current signal I
cOMstart to discharge to building-out capacitor 210, so compensation voltage signal V
cOMdecline.
As shown in Figure 5, ramp signal V-
rAMPapproximate greatly current detection signal V
cSwith sawtooth waveforms V
sAWsummation.So within the opening time, ramp signal V-
rAMPalso increase along with the time.At time point t
2, ramp signal V-
rAMPexceed compensation voltage signal V
cOM, so reseted set-reset flip-floop 116, made pulse-width signal S
pWMtransition is " 0 " in logic, enters the shut-in time.Now, power switch 104 is closed, current detection signal V
cSsuddenly 0 is dropped to, so result also in ramp signal V-
rAMPchange.
Within the shut-in time, the switch 214 in amplifier 204 cuts out not conducting, so the equivalent differential gain of amplifier 204 is approximately 0, I
cOM=0.Do not charged or discharge, building-out capacitor 210 holds the compensation voltage signal V observed instantly
cOM, until next switch periods starts.
When decompression converting circuit in Fig. 1 100 arrives a lower state (steady state), the state of all signals, each switch periods at the beginning time, all should want the same.Therefore, compensation voltage signal V
cOMa switch periods beginning with at the end of, need the same value.But, compensation voltage signal V can be affected
cOMcompensating current signal I
cOMmay not be just only 0 within the opening time, and compensating current signal I
cOMabout ratio is in current detection signal V
cSwith reference voltage V
rEFdifference.This means, when lower state, current detection signal V
cSmean value within the opening time, should approximate reference voltage V
rEF.
Under CCM operation, current detection signal V
cSmean value within the opening time, will correspond to the average current value flowing through inductance 108.Fig. 6 shows Fig. 4 cover for the control result after Fig. 1, wherein, and current signal IL
1with IL
2represent respectively, inductance 108 is respectively L
1with L
2time, flow through the current value of inductance 108.As shown in Figure 3, current signal IL
1with IL
2mean value all approximately maintain V
rEF/ R
cS, wherein R
cSfor the resistance value of current sense resistor RCS.Flow through the average driving current of light-emitting diode string 106, the average current flowing through inductance 108 will be equaled.As shown in Figure 6, in one embodiment, the average current of light-emitting diode string 106 can be controlled in V accurately
rEF/ R
cS, can not change along with inductance 108.
Via above instruction, those skilled in the art also can know by inference, are used in an embodiment of Fig. 1 at Fig. 4 cover, and the average current of light-emitting diode string 106 also can not change along with the cross-pressure between power line VIN to ground power line GND.
In above embodiments of the invention, when dim signal SDIM mono-transition is forbidden energy, pulse-width signal SPWM at once just enters the shut-in time, thus flow through that inductance 108 and the electric current of light-emitting diode string 106 can be very fast drop to 0A, light-emitting diode string 106 is not luminous.Now, building-out capacitor 210 is held and is observed compensation voltage signal VCOM, equals to have remembered to make the average current of light-emitting diode string 106 reach operating condition required for VREF/RCS.Be forbidden energy once dim signal SDIM from transition, such operating condition can be used at once, and decompression converting circuit 100 just can provide about electric current at once, drives light-emitting diode string 106, makes it luminous rapidly.In other words, embodiments of the invention are for dim signal S
dIM, have reaction speed faster.
The foregoing is only preferred embodiment of the present invention, all equalizations done according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.
Claims (20)
1. can adjust an electronic installation of the direct current flowing through an element, include:
One amplifying circuit, it has a first input end, couples one first voltage signal, and its representative flows through an electric current of this element, one second input, couples a reference voltage, and an output, in order to provide an output signal, wherein, this amplifying circuit has a differential gain;
One PWM generator, according to this output signal, provides a pulse-width signal, its definable one opening time and a shut-in time, adjusts this direct current;
Wherein, when this shut-in time, this differential gain is approximately 0.
2. electronic installation as claimed in claim 1, wherein, this amplifying circuit is a transduction amplifier, provides an output current signal.
3. electronic installation as claimed in claim 1, wherein, this amplifying circuit includes a transduction amplifier, according to this first voltage signal and this reference voltage, in an output, produce an output current signal, this PWM generator includes a building-out capacitor, this amplifying circuit include that a switch is coupled to this transduction amplifier between this output and this building-out capacitor, be controlled by this pulse-width signal.
4. electronic installation as claimed in claim 1, also includes a clock generator, periodically makes this pulse-width signal enter this opening time.
5. electronic installation as claimed in claim 1, wherein, this PWM generator includes:
One comparator, has two inputs, couples this output signal receiving this amplifying circuit respectively, and a ramp signal.
6. electronic installation as claimed in claim 5, also include a clock generator, periodically make this pulse-width signal enter this opening time, wherein, this ramp signal provided by this clock generator, is a sawtooth waveforms.
7. electronic installation as claimed in claim 5, also include a clock generator, periodically make this pulse-width signal enter this opening time, wherein, this ramp signal is associated with this first voltage signal.
8. electronic installation as claimed in claim 7, wherein, the sawtooth waveforms that this ramp signal provides according to this first voltage signal and this clock generator and producing.
9. electronic installation as claimed in claim 1, wherein, when this ramp signal is higher than this output signal, this pulse-width signal enters this shut-in time.
10. electronic installation as claimed in claim 1, also includes:
One power switch, is controlled by this pulse-width signal;
One inductance element, and this element is series between a high power line and this power switch; And
One discharge diode, is connected between this power switch and this high power line.
11. electronic installations as claimed in claim 1, also include:
One power switch, is controlled by this pulse-width signal; And
One current sense resistor, is connected between this power switch and a ground power line, can provide this first voltage signal.
12. electronic installations as claimed in claim 11, also include a filter capacitor, are connected in parallel to this element.
13. electronic installations as claimed in claim 1, wherein, this PWM generator is controlled by a dim signal, and when it is forbidden energy, this pulse-width signal maintains a state of this shut-in time of definition.
14. 1 kinds of adjustment flow through the control method of a direct current of an element, include:
Receive one first voltage signal, its representative flows through an electric current of this element;
One reference signal is provided;
According to this first voltage signal and this reference signal, based on a differential gain, produce an output current signal;
According to this output current signal, produce a pulse-width signal, to adjust this direct current, wherein, this pulse-width signal defines an opening time and a shut-in time; And
When this shut-in time, this differential gain is made to be approximately 0.
15. control methods as claimed in claim 14, also include:
Accumulate this output current signal, to produce an output voltage signal;
Relatively this output voltage signal and a ramp signal; And
When this ramp signal is higher than this output voltage signal, this pulse-width signal is made to enter this shut-in time.
16. control methods as claimed in claim 15, also include:
This pulse-width signal is periodically made to enter this opening time.
17. control methods as claimed in claim 15, also include:
There is provided a sawtooth waveforms, as this ramp signal.
18. control methods as claimed in claim 15, also include:
One sawtooth waveforms is provided; And
According to this first voltage signal and this sawtooth waveforms, produce this ramp signal, as slope-compensation.
19. control methods as claimed in claim 14, also include:
Connect this element and an inductance element between a high power line and a power switch;
This power switch is controlled according to this pulse-width signal; And
Connect a discharge diode in this power switch between this high power line.
20. control methods as claimed in claim 14, also include:
This power switch is controlled according to this pulse-width signal; And
Connect this power switch between this element and a current sense resistor;
Wherein, this current sense resistor provides this first voltage signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310421205.2A CN104470031B (en) | 2013-09-16 | 2013-09-16 | The electronic installation and control method for the DC current for flowing through an element can be adjusted |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310421205.2A CN104470031B (en) | 2013-09-16 | 2013-09-16 | The electronic installation and control method for the DC current for flowing through an element can be adjusted |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104470031A true CN104470031A (en) | 2015-03-25 |
| CN104470031B CN104470031B (en) | 2017-07-28 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI603571B (en) * | 2015-09-24 | 2017-10-21 | 萬國半導體股份有限公司 | System and method for extending the maximum duty cycle of a step-down switching converter without maximum duty control |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101436386B (en) * | 2007-11-15 | 2011-06-08 | 中华映管股份有限公司 | Drive device for backlight module unit |
| CN102170732B (en) * | 2011-04-24 | 2014-02-19 | 魏其萃 | Drive circuit topological device for MR16 (Multifaceted Reflector) light-emitting diode |
| KR102001967B1 (en) * | 2011-11-03 | 2019-10-02 | 삼성전자주식회사 | LED driving apparatus, method for driving the LED and display apparatus using the same |
| US8780590B2 (en) * | 2012-05-03 | 2014-07-15 | Hong Kong Applied Science & Technology Research Institute Company, Ltd. | Output current estimation for an isolated flyback converter with variable switching frequency control and duty cycle adjustment for both PWM and PFM modes |
-
2013
- 2013-09-16 CN CN201310421205.2A patent/CN104470031B/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI603571B (en) * | 2015-09-24 | 2017-10-21 | 萬國半導體股份有限公司 | System and method for extending the maximum duty cycle of a step-down switching converter without maximum duty control |
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|---|---|
| CN104470031B (en) | 2017-07-28 |
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