CN102360541A - Power switching circuit - Google Patents
Power switching circuit Download PDFInfo
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- CN102360541A CN102360541A CN2011103173865A CN201110317386A CN102360541A CN 102360541 A CN102360541 A CN 102360541A CN 2011103173865 A CN2011103173865 A CN 2011103173865A CN 201110317386 A CN201110317386 A CN 201110317386A CN 102360541 A CN102360541 A CN 102360541A
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Abstract
The invention provides a power switching circuit suitable for driving a light emitting semiconductor module. The power switching circuit comprises a DC (Direct Current) power source used for providing a first DC signal, a converter coupled to the DC power source, used for converting the first DC signal into a second DC signal to drive the light emitting semiconductor module and including a first switching element, a DC sensor coupled to the first switching element and used for sensing current of the first switching element so as to generate a sensing current signal, and a controller coupled to the DC sensor and used for generating a control signal according to the sensing current signal to control the first switching element, wherein when the current sensor senses that the direction of the current flowing through the first switching element is opposite to a preset direction, the controller generates the control signal corresponding to the current sensing signal provided by the current sensor at this moment and transmits the control signal to the first switching element to stop the first switching element. The power switching circuit provided by the invention prevents a counter-current phenomenon.
Description
Technical field
The present invention relates to a kind of power-switching circuit, particularly relates to the power-switching circuit that is used for driven for emitting lights diode string.
Background technology
Light emitting diode (LED) is the light fixture of a new generation, and it has advantages such as power saving and long service life, therefore, has been widely used in various device, particularly is applied in the backlight module of flat-panel screens (like LCD).
Light emitting diode in the flat-panel screens needs direct-current drive to light light emitting diode usually, generally needs direct current transducer (DC-DC converter) circuit, will import that power supply boosts or the step-down conversion to light light emitting diode.
With reference to Fig. 1, Fig. 1 has illustrated the circuit diagram of existing driven for emitting lights diode string, and it comprises direct supply 11, buck converter 12, light emitting diode string 13 and current regulator 14.Wherein, the buck converter 12 direct current I that can direct supply 11 be provided
IConvert direct current I into
OWith driven for emitting lights diode string 13; The electric current that current regulator 14 is regulated light emitting diode string 13 is with the give out light luminous intensity of diode of control.Buck converter 12 comprises on-off element Q
1, inductance L, capacitor C and diode D.Its principle of work mainly is, t ∈ [0, DT
S] lining, on-off element Q
1Conducting, diode D end, inductance L energy storage and capacitor C charging, wherein, T
SBe on-off element Q
1Cycle of control signal, D is the dutycycle of control signal for this reason; At t ∈ [DT
S, T
S] lining, on-off element Q
1By, diode D conducting, inductance L and capacitor C are to light emitting diode string 13 discharges, to light light emitting diode.But, in the circuit of existing driven for emitting lights diode string 13, can cause sizable power loss to the diode D on the path of light emitting diode string 13 discharges in inductance L.
Because mos field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor; MOSFET) has the characteristic of low on-resistance and two-way admittance; Therefore; Those skilled in the art have proposed employing switch MOS FET and have replaced existing diode D one-tenth synchronous rectification control, and to improve the efficient of buck converter 12, physical circuit is with reference to Fig. 2.
Fig. 2 has illustrated another circuit diagram of existing driven for emitting lights diode string, and it comprises power supply 21, step-down controller 22, light emitting diode string 23, current regulator 24, feedback voltage sensing circuit 25 and controller 26.Wherein, the buck converter 22 direct current I that can direct supply 21 be provided
IConvert direct current I into
OWith driven for emitting lights diode string 23; The electric current that current regulator 24 is regulated light emitting diode string 23 is with the give out light luminous intensity of diode of control; The feedback voltage V that controller 26 is provided according to feedback voltage sensing circuit 25
FBThe feedback current I that provides with current regulator 24
FBProduce control signal with CS Q
1, Q
2Buck converter 22 comprises on-off element Q
1, on-off element Q
2, inductance L and capacitor C.Feedback voltage sensing circuit 25 comprises resistance R
1And resistance R
2, the feedback voltage V of its sensing
FBVoltage V with light emitting diode string 23 two ends
ORelevant.In this driving circuit 2, its principle of work mainly is, t ∈ [0, DT
S] lining, on-off element Q
1Conducting, on-off element Q
2End, inductance L energy storage and capacitor C charging are at t ∈ [DT
S, T
S] lining, promptly at (1-D) T
SIn cycle, on-off element Q
1By, on-off element Q
2Conducting, inductance L and capacitor C are to light emitting diode string 23 discharges, to light light emitting diode.
In the practice, possibly carry out light modulation to light emitting diode, it has been generally acknowledged that light emitting diode lighted to be regarded as heavy duty, light emitting diode does not have to light and is regarded as underloading, is in other states between heavy duty and the underloading certainly in addition.When heavy duty, circuit shown in Figure 2 can be raised the efficiency, and still, when underloading, capacitor C has the contrary situation of sending energy, by power switch Q
2Release and to operate.
With reference to Fig. 3, Fig. 3 has illustrated the current waveform synoptic diagram of circuit shown in Figure 2 when light condition.As shown in Figure 3, the adverse current of appearance (Reverse current) phenomenon is arranged, because on-off element Q on the inductance L
2For MOSFET pipe is the two-way admittance element, when capacitor C is contrary when sending energy, output voltage V
OReverse drive on-off element Q
2And make its conducting, there is reverse electric current to flow through on the inductance L thereby make, and then makes and at this moment, can cause output voltage V by the electric current branch cause originally the being supplied to light emitting diode string 23 on-off element Q2 that flows through
ODescend, make the electric current of light emitting diode unstable, and then cause light emitting diode to produce the problem of flicker.
Summary of the invention
In order to address the above problem, the present invention proposes a kind of power-switching circuit, is suitable for driving an emitting semiconductor module, comprises: a direct current power supply, in order to one first direct current signal to be provided; One converter is coupled to said direct supply, and in order to said first direct current signal being converted into one second direct current signal driving said emitting semiconductor module, and said converter comprises one first on-off element; The current sense device is coupled to said first on-off element always, produces a sensed current signal in order to the electric current of said first on-off element of sensing; And a controller, be coupled to said direct current sensor, in order to produce a control signal according to said sensed current signal to control said first on-off element; Wherein, When said current sensor senses the sense of current of said first on-off element of flowing through when opposite with a predetermined direction; Said controller will the said control signal of corresponding generation transfer to said first on-off element according to the current sensing signal that this moment, current sensor was provided, so that said first on-off element ends.
Preferably, said converter is a buck converter.
Preferably, said step-down controller also comprises: a second switch element (Q1) is coupled to said direct supply; One inductance, the one of which end sees through a first node and is coupled to said second switch element, and said first on-off element is coupled to said first node; And an electric capacity, it sees through the other end that a Section Point is coupled to said inductance.
Preferably, said power-switching circuit also comprises: a feedback voltage sensing circuit is coupled to said Section Point, in order to a feedback voltage signal to said controller to be provided; And a current regulator, be coupled to said emitting semiconductor module, in order to regulating the electric current of emitting semiconductor module, and a feedback current signal to said controller is provided; Wherein, Said controller produces said control signal to control said first on-off element and said second switch element according to said feedback voltage signal, said feedback current signal and said sensed current signal; And; When said current sensor senses the sense of current of said first on-off element of flowing through when opposite with said predetermined direction, said controller produces control signal with correspondence so that said first on-off element and said second switch element all end.。
Preferably, said first on-off element and said second switch element are mos field effect transistor.
By on can know; The circuit of power source conversion proposed by the invention; It has current sensor and carries out sensing with the electric current to first on-off element of flowing through; When the direction of current that senses first on-off element of flowing through is will be with before direction (preset direction) opposite; Then controller sends at once and controls signal to first on-off element and second switch element and make first on-off element and the second switch element all ends, thereby has prevented the adverse current phenomenon and stablized the output voltage of converter, and then has avoided light emitting diode because loading undertension above that and cause the problem of its flicker.
Description of drawings
Fig. 1 has illustrated the circuit diagram of existing driven for emitting lights diode string;
Fig. 2 has illustrated another circuit diagram of existing driven for emitting lights diode string;
Fig. 3 has illustrated the current waveform synoptic diagram of circuit shown in Figure 2 when light condition;
Fig. 4 has illustrated the circuit diagram of the power-switching circuit of an embodiment of the present invention; And
Fig. 5 has illustrated the current waveform synoptic diagram of power-switching circuit shown in Figure 4 when operation.
Embodiment
Below will and specify clear explaination embodiment of the present invention with accompanying drawing, for the purpose of simplifying accompanying drawing, some known habitual structures and assembly will illustrate with the mode of simple signal in the accompanying drawings.
With reference to Fig. 4, Fig. 4 has illustrated the circuit diagram of the power-switching circuit of an embodiment of the present invention.
As shown in Figure 4, power-switching circuit 4 comprises: a direct current power supply 41, a converter 42, an emitting semiconductor module 43, current regulator 44, feedback voltage sensing circuit 45 and controller 46.In this embodiment, with respect to available circuit shown in Figure 2, power-switching circuit 4 also comprises a current sensor 47.Wherein, the converter 42 first direct current signal I that can direct supply 41 be provided
IConvert one second direct current signal I into
OWith driven for emitting lights semiconductor module 43; Current regulator 44 is regulated the luminous intensity of the electric current of emitting semiconductor module 43 with control emitting semiconductor module; The feedback voltage signal V that controller 46 is provided according to feedback voltage sensing circuit 45
FB, the feedback current signal I that provides of current regulator 44
FBReach the sensed current signal I that current sensor 47 is provided
SProduce a control signal with CS converter 42.
In this embodiment, direct supply 41 preferably, is direct voltage source.
In this embodiment, converter 42 is a buck converter (BUCK Converter), comprises the first on-off element Q
2, second switch element Q
1, inductance L and capacitor C.Wherein, an end of inductance L and on-off element Q
1Be coupled to first node N
1, on-off element Q
2Be coupled to this node N
1, the other end of capacitor C and inductance L is coupled to a Section Point N
2In this embodiment, on-off element Q
1, Q
2, preferably, be mos field effect transistor (MOSFET).In this embodiment, current sensor 47 can be used for senses flow through on-off element Q
2Electric current I
Q2, to obtain aforementioned current sensing signal I
S, especially, when current sensor 47 senses the on-off element Q that flows through
2Electric current I
Q2The flow direction during with before current opposite in direction, when promptly opposite with a predetermined direction, the controller 46 current sensing signal I that will be provided according to current sensor 47 this moment so
SProduce control signal with CS element Q
2And it is ended.
In this embodiment, emitting semiconductor module 43 is a light emitting diode string, and still, what need explanation is, also can be other emitting components, and not as limit, and its connected mode is not limited to series system, also can other connected modes.
In this embodiment, feedback voltage sensing circuit 45 comprises resistance R
1And resistance R
2, the feedback voltage signal V of its sensing
FBTransfer to controller 46.In this embodiment, this feedback voltage signal V
FBBe the voltage V that is used for reflecting emitting semiconductor module 43 two ends
O, promptly the output voltage of converter 42 can be known V by voltage divider principle
FB=(R
2/ (R
1+ R
2) V
O), therefore, sense voltage signal V
FBJust can learn the voltage V at emitting semiconductor module 43 two ends
O
Please with reference to Fig. 5, Fig. 5 has illustrated the current waveform synoptic diagram of power-switching circuit shown in Figure 4 when operation again.
The following while is with reference to Fig. 4 and Fig. 5, and the running of power-switching circuit 4 is described in detail.
At first, at D
1T
SDuring this time, controller 46 is according to feedback voltage signal V
FB, feedback current signal I
FBAnd to on-off element Q
2Carry out the sensed current signal I of sensing gained
SProduce control signal CS element Q
1With on-off element Q
2, during this period in, on-off element Q
1Conducting, on-off element Q
2End, then the electric current I that provided of direct supply 41
IAt the on-off element Q that flows through
1The back flows into inductance L and capacitor C, thereby makes inductance L energy storage (I
LForward increases) and capacitor C charging (I
CForward increases).
Then, at D
2T
SDuring this time, in like manner, controller 46 is according to feedback voltage signal V
FB, feedback current signal I
FBAnd to on-off element Q
2Carry out the sensed current signal I of sensing gained
SProduce control signal CS element Q
1With on-off element Q
2, can know by Fig. 5, during this period in, on-off element Q
1By, on-off element Q
2Conducting, then inductance L or capacitor C will with emitting semiconductor module 43 and on-off element Q
2Form a loop, at this moment, inductance L and capacitor C will be to 43 discharges of emitting semiconductor module, to light light-emitting diode.
What need to stress is, when current sensor 47 has just sensed the on-off element Q that flows through
2Electric current I
Q2The flow direction will be with it D between early stage
2T
SElectric current I
Q2Current opposite in direction the time, promptly this moment be about to produce the adverse current phenomenon of mentioning of the prior art, specifically, capacitor C will be against sending energy to inductance L and on-off element Q
2Thereby, make voltage V
OReduce, and then cause LED flash.And in this embodiment, when the adverse current phenomenon has just produced, current sensor 47 will send current sensing signal I at once
STo controller 46, and controller 46 sends and controls signal to on-off element Q
1, Q
2And make CS element Q
1, Q
2End simultaneously, thereby avoid the energy of capacitor C to run off, and then make voltage V
OMaintain position surely, and then avoid the flicker problem of light emitting diode.In this embodiment, D during process
3T
SAfter, controller 46 will send again and make on-off element Q
1Conducting, on-off element Q
2The control signal of ending is with CS element Q
1, Q
2State.
By on can know, the circuit of power source conversion proposed by the invention, it has current sensor with to the on-off element Q that flows through
2Electric current carry out sensing, when sensing I
Q2Direction of current when will be with before direction (preset direction) opposite, then controller sends at once and controls signal to on-off element Q
1, Q
2And make on-off element Q
1, Q
2All end, thereby prevented the adverse current phenomenon and stablized output voltage V
O, and then avoided light emitting diode to cause the problem of its flicker because loading undertension above that.
In the preceding text, illustrate and describe embodiment of the present invention.But those skilled in the art can understand, and under situation without departing from the spirit and scope of the present invention, can also specific embodiments of the invention do various changes and replacement.These changes and replacement all drop in claims of the present invention institute restricted portion.
Claims (5)
1. a power-switching circuit is suitable for driving an emitting semiconductor module, it is characterized in that, comprises:
One direct current power supply is in order to provide one first direct current signal;
One converter is coupled to said direct supply, and in order to said first direct current signal being converted into one second direct current signal driving said emitting semiconductor module, and said converter comprises one first on-off element (Q
2);
The current sense device is coupled to said first on-off element always, in order to senses flow through the electric current of said first on-off element and produce a sensed current signal; And
One controller is coupled to said direct current sensor, in order to produce a control signal according to said sensed current signal to control said first on-off element;
Wherein, When said current sensor senses the sense of current of said first on-off element of flowing through when opposite with a predetermined direction; Said controller will the said control signal of corresponding generation transfer to said first on-off element according to the current sensing signal that this moment, current sensor was provided, so that said first on-off element ends.
2. power-switching circuit according to claim 1 is characterized in that, said converter is a buck converter.
3. power-switching circuit according to claim 2 is characterized in that, said step-down controller also comprises:
One second switch element (Q1) is coupled to said direct supply;
One inductance, the one of which end sees through a first node and is coupled to said second switch element, and said first on-off element is coupled to said first node; And
One electric capacity, it sees through the other end that a Section Point is coupled to said inductance.
4. power-switching circuit according to claim 3 is characterized in that, also comprises:
One feedback voltage sensing circuit is coupled to said Section Point, in order to a feedback voltage signal to said controller to be provided; And
One current regulator is coupled to said emitting semiconductor module, in order to the electric current of adjusting emitting semiconductor module, and a feedback current signal to said controller is provided;
Wherein, Said controller produces said control signal to control said first on-off element and said second switch element according to said feedback voltage signal, said feedback current signal and said sensed current signal; And; When said current sensor senses the sense of current of said first on-off element of flowing through when opposite with said predetermined direction, said controller produces control signal with correspondence so that said first on-off element and said second switch element all end.
5. power-switching circuit according to claim 3 is characterized in that, said first on-off element and said second switch element are mos field effect transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011103173865A CN102360541A (en) | 2011-10-12 | 2011-10-12 | Power switching circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011103173865A CN102360541A (en) | 2011-10-12 | 2011-10-12 | Power switching circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102360541A true CN102360541A (en) | 2012-02-22 |
Family
ID=45585862
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011103173865A Pending CN102360541A (en) | 2011-10-12 | 2011-10-12 | Power switching circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102360541A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106256085A (en) * | 2014-05-29 | 2016-12-21 | 住友电气工业株式会社 | Abnormal detector |
| CN106712509A (en) * | 2016-12-21 | 2017-05-24 | 深圳市华星光电技术有限公司 | Power circuit and liquid crystal display |
| JP2021048174A (en) * | 2019-09-17 | 2021-03-25 | パナソニックＩｐマネジメント株式会社 | Semiconductor light source drive device and projection type video display device |
-
2011
- 2011-10-12 CN CN2011103173865A patent/CN102360541A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106256085A (en) * | 2014-05-29 | 2016-12-21 | 住友电气工业株式会社 | Abnormal detector |
| CN106256085B (en) * | 2014-05-29 | 2018-09-18 | 住友电气工业株式会社 | Abnormal detector |
| CN106712509A (en) * | 2016-12-21 | 2017-05-24 | 深圳市华星光电技术有限公司 | Power circuit and liquid crystal display |
| CN106712509B (en) * | 2016-12-21 | 2019-07-23 | 深圳市华星光电技术有限公司 | A kind of power circuit and liquid crystal display |
| JP2021048174A (en) * | 2019-09-17 | 2021-03-25 | パナソニックＩｐマネジメント株式会社 | Semiconductor light source drive device and projection type video display device |
| JP7386437B2 (en) | 2019-09-17 | 2023-11-27 | パナソニックＩｐマネジメント株式会社 | Semiconductor light source drive device and projection type image display device |
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| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20120222 |