CN100449918C - Output voltage adjustable dc-dc conversion circuit - Google Patents
Output voltage adjustable dc-dc conversion circuit Download PDFInfo
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- CN100449918C CN100449918C CNB2006101107586A CN200610110758A CN100449918C CN 100449918 C CN100449918 C CN 100449918C CN B2006101107586 A CNB2006101107586 A CN B2006101107586A CN 200610110758 A CN200610110758 A CN 200610110758A CN 100449918 C CN100449918 C CN 100449918C
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Abstract
The invention relates to a direct-current-direct-current convert circuit, which comprises: one direct-current power source, one direct-current-direct-current converter, one power manage chip and one load, wherein the load can be backlight source of liquid crystal display; said power manage chip can control the direct-current-direct-current converter to convert the direct-current voltage into one output voltage to power the load; and based on the minimum voltage change of said load, controls the direct-current-direct-current converter to adjust its output voltage to reach the minimum voltage needed by load.
Description
Technical field
The direct current that the present invention relates to a kind of adjustable output voltage is to DC converting circuit, and particularly a kind of direct current can be adjusted to its output voltage the needed minimum voltage of load to DC converting circuit.
Background technology
As everyone knows, need utilize a backlight to light its display frame in the general LCD, and backlight is a power consumption components main in the LCD, if can effectively reduce the power consumption of backlight, can significantly reduce the whole power consumption of LCD.Therefore, how to reduce the power consumption of backlight, promptly become one of important topic of circuit design in the LCD.
See also Fig. 1, it is the Organization Chart that shows the available circuit of an offered load voltage, the voltage transitions that direct current transducer 104 is provided DC power supply 102 comprising a direct current becomes an output voltage V out required with offered load 108, load 108 herein can be Backlight For Liquid Crystal Display Panels, and this backlight can be a plurality of light-emitting diodes.One current feedback unit, 110 control flows make the electric current of this load 108 of flowing through keep stable through the electric current of load 108.Simultaneously, output voltage V out also is supplied to the resistance R 1 and the R2 of series connection, makes series resistance R1 and R2 with output voltage V out dividing potential drop, and provides a feedback voltage Vfb to a power management chip 106 between resistance R 1 and R2.This power management chip 106 is adjusted output voltage V out to reach the required voltage swing of these load 108 reality according to feedback voltage Vfb control direct current to direct current transducer 104.
Yet, because series resistance R1 and R2 are made as definite value to cooperate the required voltage of load 108.When load 108 actual required voltages reduce, this moment, output voltage V out still was a definite value, and the feedback voltage Vfb that is produced via series resistance R1 and R2 dividing potential drop can't change to some extent, therefore can't make power management chip 106 these direct currents of control that direct current transducer 104 is removed really to reduce output voltage V out.At this moment, too high output voltage V out not only can increase the power consumption of load 108, and also can shorten the useful life of load 108.
Therefore, if the variation of load 108 required voltages can be fed back to power management chip 106 effectively, with the control direct current direct current transducer 104 is gone to produce and be fit to the required output voltage V out of load 108, not only can effectively reduce the power consumption of load 108, also can prolong the useful life of load 108.
Summary of the invention
Therefore, the direct current that main purpose of the present invention is a kind of adjustable output voltage is provided can be adjusted into its output voltage the required minimum voltage of load to DC converting circuit, with the power consumption of effective reduction load, and prolongs the useful life of load.
According to above-mentioned purpose of the present invention, the invention provides a kind of direct current to DC converting circuit, it comprises that a direct current power supply, a direct current are to direct current transducer (DC-DC Converter), a power management chip, a load, a controller, a current control circuit and a resistance-variable circuit, wherein this load can be the backlight in the LCD, and this backlight can be the light-emitting diode of a plurality of series connection.Direct current of the present invention to DC converting circuit in, this power management chip is controlled the voltage transitions that this direct current supplied a direct current power supply to direct current transducer and is become an output voltage required with offered load.This current control circuit is used to make the flow through electric current of load to keep stable.When the required voltage of this load changed, its residual voltage can change thereupon, made this controller be able to adjust according to the variation of residual voltage the equivalent resistance of this resistance-variable circuit.When the equivalent resistance of resistance-variable circuit changed, the feedback voltage of resistance-variable circuit can change thereupon.Take this, this power management chip can be controlled this direct current according to the variation of feedback voltage direct current transducer is adjusted its output voltage, makes output voltage can reach the required minimum voltage of load.
Direct current of the present invention also can adopt a voltage control circuit to replace aforesaid controller and resistance-variable circuit to DC converting circuit, removes to adjust feedback voltage with the variable quantity according to residual voltage.
Direct current of the present invention can be according to the required change in voltage of load reality to DC converting circuit, feed back to power management chip effectively, with the control direct current direct current transducer is removed to produce the actual required minimum output voltage of this load, not only can effectively reduce the power consumption of load, also can prolong the useful life of load.
Description of drawings
Fig. 1 is the circuit framework figure of the direct current of prior art to DC converting circuit.
Fig. 2 is the circuit framework figure of direct current of the present invention to first embodiment of DC converting circuit.
Fig. 3 is the circuit framework figure of direct current of the present invention to second embodiment of DC converting circuit.
Fig. 4 is the circuit framework figure of direct current of the present invention to the 3rd embodiment of DC converting circuit.
Fig. 5 is the detailed circuit diagram of the first embodiment of the present invention.
Fig. 6 is the detailed circuit diagram of the second embodiment of the present invention.
Fig. 7 is the detailed circuit diagram of the third embodiment of the present invention.
The reference numeral explanation
202,302,402,502,602,702 DC power supply
204,304,404,504,604,704 direct currents are to direct current transducer
206,306,406,506,606,706 power management chips
208,308,408,508,608,708 loads
210,310,510,610 controllers
212,312,412,512,612,712 current control circuits
214,314,514,614 resistance-variable circuit
316,416,616,716 minimum voltage selectors
410,710 voltage control circuits
The Vout output voltage
The Vfb feedback voltage
V1, V11, V12...V1n residual voltage
Embodiment
See also Fig. 2, be the circuit framework figure of direct current of the present invention to first embodiment of DC converting circuit, it comprises: a direct current power supply 202, a direct current are to direct current transducer (DC-DC Converter) 204, one power management chip 206, a load 208, a controller 210, a current control circuit 212 and a resistance-variable circuit 214, wherein, this load 208 can be the backlight in the LCD, and this backlight can be the light-emitting diode of a plurality of series connection.This power management chip 206 can be a pulse width modulating chip (Pulse-Width Modulator IC, PWM IC).In this first embodiment, the voltage transitions that power management chip 206 these direct currents of control are supplied a direct current power supply 202 to direct current transducer 204 becomes an output voltage V out required with offered load 208.This current control circuit 212 is used to make the flow through electric current of load 208 to keep stable.When load 208 actual required voltages change, impel residual voltage V1 also can change thereupon, this controller 210 can be adjusted the equivalent resistance of this resistance-variable circuit 214 according to the variation of this residual voltage V1 by this.When the equivalent resistance of resistance-variable circuit 214 changed, the resistance R 22 of series connection and the feedback voltage Vfb between the resistance-variable circuit 214 can change thereupon.Power management chip 206 according to the variation of feedback voltage Vfb control direct current to direct current transducer 204 to adjust its output voltage V out, make output voltage V out can reach the actual required voltage swing of load 208.
For example, when the voltage of load 208 actual needs reduced, residual voltage V1 can rise, and then controller 210 can increase the equivalent resistance of this resistance-variable circuit 214, make the cross-pressure between resistance R 22 and the resistance-variable circuit 214 become big, promptly feedback voltage Vfb rises thereupon.Power management chip 206 makes direct current reduce output voltage V out to direct current transducer 204 according to the feedback voltage Vfb that rises at this moment, to reach the required magnitude of voltage of present load 208 reality.Otherwise, when load 208 actual required voltages rose, residual voltage V1 then descended, and made this controller 210 can reduce the equivalent resistance of resistance-variable circuit 214, cross-pressure between resistance R 22 and the resistance-variable circuit 214 is diminished, and promptly feedback voltage Vfb decreases.Power management chip 206 makes direct current improve output voltage V out to direct current transducer 204 according to the feedback voltage Vfb that reduces at this moment.By this, direct current of the present invention can be adjusted output voltage V out at any time according to the required change in voltage of load 208 reality to DC converting circuit, makes output voltage V out remain on the required minimum voltage value of load 208 reality.
See also Fig. 3, be the circuit framework figure of direct current of the present invention to second embodiment of DC converting circuit, it comprises that a direct current power supply 302, a direct current are to direct current transducer 304, a power management chip 306, a load 308, a controller 310, a current control circuit 312, a resistance-variable circuit 314 and a minimum voltage selector 316.The difference of second embodiment and first embodiment is: the load 208 among first embodiment is single string light-emitting diode, and the load 308 among second embodiment is an array LED, this array LED comprises many string light-emitting diodes, and every string light-emitting diode is the light-emitting diode of a plurality of series connection.Because the load 308 among second embodiment is many string light-emitting diodes, and the required minimum voltage of every string light-emitting diode is not quite similar, for making every string light-emitting diode all have enough voltage to keep normal operation, so direct current must be an establishing criteria with required voltage soprano in these many string light-emitting diodes to the output voltage V out of direct current transducer 304, offers the required minimum voltage of these many string light-emitting diodes.Therefore, the lowest among residual voltage V11, the V12...V1n, represent that the required voltage of this string light-emitting diode is the highest, select respectively to go here and there the lowest among residual voltage V11, the V12...V1n of light-emitting diode so utilize minimum voltage selector 316, offer the foundation of controller 310 as the equivalent resistance of adjusting resistance-variable circuit 314, then according to the variation of feedback voltage Vfb, the control direct current produces the required minimum output voltage Vout of load 308 reality to direct current transducer 304 to power management chip 306.
See also Fig. 4, be the circuit framework figure of direct current of the present invention the 3rd embodiment of DC converting circuit.The 3rd embodiment comprise a direct current power supply 402, a direct current to direct current transducer 404, a power management chip 406, a load 408, a voltage control circuit 410, a current control circuit 412, with a minimum voltage selector 416.Be with the difference of previous embodiment: the 3rd embodiment respectively goes here and there the lowest among residual voltage V11, the V12...V1n of light-emitting diode with voltage control circuit 410 according to what minimum voltage selector 416 was selected, remove to adjust the cross-pressure of series resistance R41, R42 with the variable quantity of this minimum residual voltage, to reach the purpose of adjusting feedback voltage Vfb.For instance, when its required voltage value of required voltage soprano in many strings light-emitting diode descends, its residual voltage value of the lowest can rise among residual voltage V11, the V12...V1n, voltage control circuit 410 increases total cross-pressure of series resistance R41, R42 according to the residual voltage of this rising, and then feedback voltage Vfb rises thereupon.This moment, power management chip 406 was according to the feedback voltage Vfb that rises, and made direct current reduce output voltage V out to direct current transducer 404, to meet the required magnitude of voltage of present load 408.Otherwise, when its required voltage value of required voltage soprano in many strings light-emitting diode rises, its residual voltage value of the lowest can descend among residual voltage V11, the V12...V1n, then voltage control circuit 410 reduces total cross-pressure of series resistance R41, R42 according to the residual voltage of this decline, and then feedback voltage Vfb decreases.This moment, power management chip 406 was according to the feedback voltage Vfb that reduces, and made direct current increase output voltage V out to direct current transducer 404, to meet the required magnitude of voltage of present load 408.
Seeing also Fig. 5, is the detailed circuit diagram of first embodiment.The voltage transitions that power management chip 506 control direct currents are supplied DC power supply 502 to direct current transducer 504 becomes an output voltage V out with offered load 508, and wherein, this load 508 can be a single string light-emitting diode.Current control circuit 512 makes the electric current of the load 508 of flowing through keep stable.When load 508 actual required voltages changed, residual voltage V1 can change thereupon, and the equivalent resistance of resistance-variable circuit 514 is adjusted in 510 variations according to residual voltage V1 of controller.In Fig. 5, controller 510 utilizes amplifier A5 oppositely to amplify residual voltage V1 value, resistance-variable circuit 514 utilizes transistor Q51 to adjust the equivalent resistance of resistance-variable circuit 514 according to the residual voltage V1 value that is reversed amplification, wherein this transistor Q51 can be two-carrier junction transistor (Bipolar Junction Transistor, BJT), field-effect transistor (Field-EffectTransistor, FET) or the transistor of other type.
The anode input value of aforementioned amplifier A5 is a reference voltage Vref, and this reference voltage Vref must equate that reference voltage Vref can utilize a pi controller (PI controller, not shown) to make Vref=V1 with residual voltage V1 value; Residual voltage V1 then inputs to the negative terminal input of amplifier A5 via resistance R 51.When load 508 actual required voltages descended, residual voltage V1 can rise.According to the ratio of resistance R in the controller 510 51 with R52, after this residual voltage V1 can be exaggerated the reverse amplification of device A5, export the grid of transistor Q51 to, the grid voltage of this transistor Q51 is risen, so its equivalent resistance descends, the equivalent resistance of resistance-variable circuit 514 descends thereupon, and then the cross-pressure at resistance-variable circuit 514 two ends also descends thereupon, that is feedback voltage Vfb reduces.Power management chip 506 makes direct current improve its output voltage V out to direct current transducer 504 according to the feedback voltage Vfb that reduces at this moment.Therefore by adjusting this output voltage V out, can make output voltage V out remain on the required minimum voltage value of load 508 reality.In Fig. 5, also comprise the design of protective circuit, when fault made the complete conducting of transistor Q51, resistance R 55 can limit its maximum output voltage to reach the purpose of overvoltage protection; And when fault ended transistor Q51 fully, resistance R 56 can be avoided the feedback voltage Vfb suspension joint and cause circuit erroneous action.
Seeing also Fig. 6, is the detailed circuit diagram of second embodiment.To the introduction of second embodiment, the load 608 among Fig. 6 is an array LED as before, and this array LED comprises many string light-emitting diodes, and every string light-emitting diode is the light-emitting diode of a plurality of series connection.Therefore need provide a minimum voltage selector 616 to select minimum residual voltage value in many string light-emitting diodes.Minimum voltage selector 616 connects a diode respectively with each string light-emitting diode tail end, make and respectively go here and there residual voltage V11, the V12...V1n of light-emitting diode and be coupled to the input of controller 610 in the reverse bias mode, so can select the minimum remaining magnitude of voltage of residual voltage V11, V12...V1n by this diode.
Seeing also Fig. 7, is the detailed circuit diagram of the 3rd embodiment.In Fig. 7, the present invention adopt a voltage control circuit 710 according to minimum voltage selector 716 selected respectively go here and there the lowest among residual voltage V11, the V12...V1n of light-emitting diode, remove to adjust the cross-pressure of series resistance R75, R76 with the variable quantity of minimum residual voltage, to reach the purpose of adjusting feedback voltage Vfb.Voltage control circuit 710 utilizes an amplifier A7, the lowest among residual voltage V11, the V12...V1n is inputed to the anode input of amplifier A7 via resistance R 72; The negative terminal input of amplifier A7 then connects ground connection via resistance R 73.Amplifier A7 amplifies this minimum residual voltage value according to the ratio of resistance R 73, R74, with the cross-pressure of adjustment series resistance R75, R76, and then adjusts feedback voltage Vfb.When its required voltage value of required voltage soprano in many strings light-emitting diode descends, its residual voltage value of the lowest can rise among residual voltage V11, the V12...V1n, voltage control circuit 710 amplifies this residual voltage value increases total cross-pressure of series resistance R75, R76, and then feedback voltage Vfb rises thereupon.Power management chip 706 makes direct current reduce its output voltage V out to direct current transducer 704 according to the feedback voltage Vfb that rises at this moment, to reach the required magnitude of voltage of present load 708 reality.
Compared to prior art, direct current of the present invention can be according to the required change in voltage of load reality to DC converting circuit, feed back to power management chip effectively, with the control direct current direct current transducer is removed to produce the actual required minimum output voltage of load, not only can effectively reduce the power consumption of load, also can prolong the useful life of load.
The above person only is a better embodiment of the present invention, and the personage who has the knack of this case technology such as helps the equivalence of doing according to spirit of the present invention and modifies or variation, all is covered by in the appended claim.
Claims (19)
1. a direct current is to DC converting circuit, and it comprises:
One load;
One direct current is to direct current transducer, converts the direct voltage of a direct current power supply to an output voltage with offered load;
One resistance-variable circuit, it has variable equivalent resistance, and exports a feedback voltage according to this equivalence resistance value;
One controller changes the equivalent resistance of adjusting this resistance-variable circuit according to the residual voltage of this load, and then adjusts the feedback voltage of this resistance-variable circuit output; And
One power management chip in order to the feedback voltage of being exported according to this resistance-variable circuit, is controlled this direct current direct current transducer is adjusted its output voltage to the actual required voltage swing of this load.
2. direct current as claimed in claim 1 is to DC converting circuit, and wherein, this controller has an amplifier, in order to amplify this residual voltage; This resistance-variable circuit has a transistor, changes this transistorized equivalent resistance in order to the residual voltage according to this amplification.
3. direct current as claimed in claim 2 is to DC converting circuit, and wherein, this resistance-variable circuit comprises a protective circuit in addition, in order to when this transistor breaks away from its normal range of operation, avoids this direct current that DC converting circuit is produced misoperation.
4. direct current as claimed in claim 3 is to DC converting circuit, and wherein, it is in parallel with this transistor that this protective circuit has at least one resistance.
5. direct current as claimed in claim 1 is to DC converting circuit, and wherein, this load is a single string light-emitting diode, and it comprises the light-emitting diode of a plurality of series connection.
6. direct current as claimed in claim 1 is to DC converting circuit, and wherein, this load is an array formula light-emitting diode, and it comprises many string light-emitting diodes, and every string light-emitting diode has the light-emitting diode of a plurality of series connection.
7. direct current as claimed in claim 6 is to DC converting circuit, and other comprises a minimum voltage selector, in order to selecting minimum residual voltage in these many string light-emitting diodes, and exports this minimum residual voltage to this controller.
8. direct current as claimed in claim 7 is to DC converting circuit, wherein, this minimum voltage selector has a plurality of diodes, each diode is connected to respectively respectively goes here and there the tail end of light-emitting diode, makes respectively to go here and there the residual voltage of light-emitting diode and be coupled to this controller by this diode in the reverse bias mode.
9. direct current as claimed in claim 1 is to DC converting circuit, and wherein, this power management chip is a pulse width modulating chip.
10. direct current as claimed in claim 1 is to DC converting circuit, and other comprises a current control circuit, uses so that the electric current of this load of flowing through keeps stable.
11. a direct current is to DC converting circuit, it comprises:
One load;
Resistor assembly;
One direct current is to direct current transducer, converts an output voltage to for should load in order to the direct voltage that a direct current power supply is supplied;
One voltage control circuit changes the cross-pressure adjusted in this resistor assembly to produce a feedback voltage in order to the residual voltage according to this load; And
One power management chip in order to the feedback voltage of exporting according to this resistor assembly, is controlled this direct current direct current transducer is adjusted its output voltage to the actual required voltage swing of this load.
12. direct current as claimed in claim 11 is to DC converting circuit, wherein, this resistor assembly comprises two resistance of series connection, make the cross-pressure of voltage control circuit, produce a feedback voltage with the tie point between two resistance of this series connection according to the series circuit two ends of two resistance compositions of this series connection of residual voltage variation adjustment of this load.
13. direct current as claimed in claim 12 is to DC converting circuit, wherein, this voltage control circuit has an amplifier, and in order to amplifying this residual voltage, and the residual voltage that will amplify exports the series circuit that two resistance of this series connection are formed to.
14. direct current as claimed in claim 11 is to DC converting circuit, wherein, this load is a single string light-emitting diode, and it comprises the light-emitting diode of a plurality of series connection.
15. direct current as claimed in claim 11 is to DC converting circuit, wherein, this load is an array formula light-emitting diode, and it comprises many string light-emitting diodes, and every string light-emitting diode has the light-emitting diode of a plurality of series connection.
16. direct current as claimed in claim 15 is to DC converting circuit, other comprises a minimum voltage selector, in order to selecting minimum residual voltage in these many string light-emitting diodes, and exports this minimum residual voltage to voltage control circuit.
17. direct current as claimed in claim 16 is to DC converting circuit, wherein, this minimum voltage selector has a plurality of diodes, each diode is connected to respectively respectively goes here and there the tail end of light-emitting diode, makes respectively to go here and there the residual voltage of light-emitting diode and be coupled to this voltage control circuit by this diode in the reverse bias mode.
18. direct current as claimed in claim 11 is to DC converting circuit, wherein, this power management chip is a pulse width modulating chip.
19. direct current as claimed in claim 11 is to DC converting circuit, other comprises a current control circuit, uses so that the electric current of this load of flowing through keeps stable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101107586A CN100449918C (en) | 2006-08-11 | 2006-08-11 | Output voltage adjustable dc-dc conversion circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006101107586A CN100449918C (en) | 2006-08-11 | 2006-08-11 | Output voltage adjustable dc-dc conversion circuit |
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| CN1909347A CN1909347A (en) | 2007-02-07 |
| CN100449918C true CN100449918C (en) | 2009-01-07 |
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| CNB2006101107586A Active CN100449918C (en) | 2006-08-11 | 2006-08-11 | Output voltage adjustable dc-dc conversion circuit |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101727170B (en) * | 2008-10-31 | 2012-05-23 | 英业达股份有限公司 | Power supply managing device for central processing unit |
| CN103179743A (en) * | 2009-03-04 | 2013-06-26 | 立锜科技股份有限公司 | Led driver with direct ac-dc conversion and control, and method and integrated circuit therefor |
| CN101950541B (en) * | 2010-07-12 | 2013-03-27 | 深圳市华星光电技术有限公司 | Backlight module and liquid crystal display |
| CN108668128A (en) * | 2017-03-29 | 2018-10-16 | 深圳市东创良盛电子技术有限公司 | A kind of television set automatization test system and test method |
| CN114399978B (en) * | 2022-03-24 | 2022-07-01 | 南京浣轩半导体有限公司 | Control method and system for dynamic energy saving of LED backlight |
| CN114708839B (en) * | 2022-04-02 | 2023-08-22 | Tcl华星光电技术有限公司 | Backlight module and display device |
| US11763760B1 (en) | 2022-04-02 | 2023-09-19 | Tcl China Star Optoelectronics Technology Co., Ltd. | Backlight module and display device |
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| CN1358057A (en) * | 2000-12-07 | 2002-07-10 | 国碁电子股份有限公司 | DC-AC converter |
| US20030151601A1 (en) * | 2002-02-09 | 2003-08-14 | Chung In Jae | Apparatus and method of driving discharge tube lamp and liquid crystal display using the same |
| CN1575080A (en) * | 2003-06-13 | 2005-02-02 | 日本航空电子工业株式会社 | Power supply for lighting |
| US20060108933A1 (en) * | 2004-11-19 | 2006-05-25 | Sheng-Feng Chen | Light emitted diode driving apparatus |
| CN1794894A (en) * | 2004-12-25 | 2006-06-28 | 鸿富锦精密工业（深圳）有限公司 | Driving device of cold-cathode fluorescent lamp |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1358057A (en) * | 2000-12-07 | 2002-07-10 | 国碁电子股份有限公司 | DC-AC converter |
| US20030151601A1 (en) * | 2002-02-09 | 2003-08-14 | Chung In Jae | Apparatus and method of driving discharge tube lamp and liquid crystal display using the same |
| CN1575080A (en) * | 2003-06-13 | 2005-02-02 | 日本航空电子工业株式会社 | Power supply for lighting |
| US20060108933A1 (en) * | 2004-11-19 | 2006-05-25 | Sheng-Feng Chen | Light emitted diode driving apparatus |
| CN1794894A (en) * | 2004-12-25 | 2006-06-28 | 鸿富锦精密工业（深圳）有限公司 | Driving device of cold-cathode fluorescent lamp |
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| CN1909347A (en) | 2007-02-07 |
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