CN106712509B - A kind of power circuit and liquid crystal display - Google Patents
A kind of power circuit and liquid crystal display Download PDFInfo
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- CN106712509B CN106712509B CN201611189682.0A CN201611189682A CN106712509B CN 106712509 B CN106712509 B CN 106712509B CN 201611189682 A CN201611189682 A CN 201611189682A CN 106712509 B CN106712509 B CN 106712509B
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- 239000004973 liquid crystal related substance Substances 0.000 title claims description 34
- 239000003990 capacitor Substances 0.000 claims abstract description 49
- 230000008859 change Effects 0.000 claims abstract description 15
- 230000005611 electricity Effects 0.000 claims description 12
- 230000005669 field effect Effects 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 2
- 101100112673 Rattus norvegicus Ccnd2 gene Proteins 0.000 description 12
- 238000000034 method Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Liquid Crystal Display Device Control (AREA)
Abstract
A kind of power circuit includes current source, switch, first and second comparator, latch, driver, second and third resistance, first capacitor, first and second electric switch, rate converter, current source is grounded by first capacitor, the anode and cathode of current source is connected to voltage input end by rate converter, so that the second electric current changes according to the voltage change that voltage input end inputs, first comparator compares the voltage in fixed voltage and first capacitor, second capacitor also passes through switch ground connection, switch is controlled by reversed pwm signal, first comparator connects driver by latch, it controls driver and exports PWM low level signal, second and third resistance is connected between voltage output end and ground, second comparator compares voltage and reference voltage at the intermediate node of second and third resistance, second comparator passes through latch Driver is connected, to control driver output PWM high level signal.The present invention improves system stability.
Description
Technical field
The present invention relates to a kind of field of display technology, more particularly, to a kind of power circuit and liquid crystal display.
Background technique
With the development of science and technology, higher and higher to the requirement of electronic equipment, for example, the performance of electronic equipment more may be used
It leans on, function is continuously increased, and more convenient to use, volume increasingly reduces, these become DC-DC (DC to DC) converter technique
It obtains more important.Currently, DC-DC scheme is fixed due to the high level turn-on time of pwm signal now, and line regulation is opposite
Poor, when input voltage fluctuation is larger, the fluctuation of output voltage also can be larger, to influence system stability.
Summary of the invention
The purpose of the present invention is to provide a kind of power circuits, to improve the stability of system.
Another object of the present invention is to provide a kind of liquid crystal displays.
To achieve the goals above, embodiment of the present invention provides the following technical solutions:
The present invention provides a kind of power circuit, be applied to liquid crystal display in, the power circuit include the first current source,
Second current source, first switch, second switch, first comparator, the second comparator, latch, driver, first resistor,
Two resistance, 3rd resistor, first capacitor, the first electric switch and the second electric switch, first current source are connected to described first
The first end of switch, to provide the first electric current, the second end of the first switch is grounded by the first resistor, and described first
Switch is controlled by the first pwm signal, and second current source is grounded by the first capacitor, described to provide the second electric current
The anode and cathode of second current source is connected to voltage input end by the rate converter, so that the second electric current is according to the voltage
Input terminal input voltage change and change, the inverting input terminal of the first comparator be connected to the first switch with it is described
Node between first resistor, the non-inverting input terminal of the first comparator are connected to second current source and first electricity
Node between appearance, and be grounded by the second switch, the second switch is controlled by the second pwm signal, first ratio
Compared with the end R that the output end of device is connected to the latch, the end S of the latch is connected to the output of second comparator
End, the second resistance and the 3rd resistor are connected between voltage output end and ground, and the reverse phase of second comparator is defeated
Enter the node that end is connected between the second resistance and the 3rd resistor, the non-inverting input terminal of second comparator receives
The output end of reference voltage, the latch is connected to driver, to control the output of the driver, the height of the driver
Voltage output end is connected to the control terminal of first electric switch, and the low-voltage output end of the driver is connected to described second
The control terminal of electric switch, the first end of first electric switch are connected to voltage input end, the second end of first electric switch
It is connected to the first end of second electric switch, the second end ground connection of second electric switch, first electric switch and described
Node between second electric switch is connected to voltage output end, the voltage output end connection load, first pwm signal with
And the second pwm signal polarity is opposite.
Wherein, the power circuit further includes inductance and the second capacitor, and the first end of the inductance is connected to described first
On node between electric switch and the second electric switch, the second end of the inductance is connected to by second capacity earth
The voltage output end.
Wherein, the power circuit further includes the 4th resistance, third capacitor and the 4th capacitor, and the 4th resistance is connected to
Between the second end of the first switch and the inverting input terminal of the first comparator, the third capacitance connection is described
Between the second end and ground of one switch, the 4th capacitance connection is between the inverting input terminal and ground of the first comparator.
Wherein, the power circuit further includes phase inverter, and the input terminal of the phase inverter receives first pwm signal,
The output end of the phase inverter is connected to the second switch, and the 2nd PWM letter is obtained after the first pwm signal is negated
Number, so that second pwm signal controls the second switch closing or opening.
Wherein, the power circuit further includes diode, and it is negative that the anode of the diode is connected to first current source
Pole, the cathode of the diode are connected to the anode of first current source.
Wherein, first electric switch and second electric switch are N-type field-effect tube, first electric switch and institute
The control terminal, first end and second end for stating the second electric switch are respectively grid, drain electrode and the source electrode of field-effect tube.
The present invention also provides a kind of liquid crystal displays, provide operating voltage including liquid crystal display panel and for the liquid crystal display panel
Power circuit, the power circuit include the first current source, the second current source, first switch, second switch, first comparator,
Second comparator, latch, driver, first resistor, second resistance, 3rd resistor, first capacitor, the first electric switch and second
Electric switch, first current source are connected to the first end of the first switch, to provide the first electric current, the first switch
Second end is grounded by the first resistor, and the first switch is controlled by the first pwm signal, and second current source passes through institute
First capacitor ground connection is stated, to provide the second electric current, the anode and cathode of second current source is connected to by the rate converter
Voltage input end, so that the second electric current changes, the first comparator according to the voltage change that the voltage input end inputs
Inverting input terminal be connected to the node between the first switch and the first resistor, the first comparator it is same mutually defeated
Enter the node that end is connected between second current source and the first capacitor, and is grounded by the second switch, it is described
Second switch is controlled by the second pwm signal, and the output end of the first comparator is connected to the end R of the latch, the lock
The end S of storage is connected to the output end of second comparator, and it is defeated that the second resistance and the 3rd resistor are connected on voltage
Between outlet and ground, the inverting input terminal of second comparator is connected between the second resistance and the 3rd resistor
The non-inverting input terminal of node, second comparator receives reference voltage, and the output end of the latch is connected to driver, with
The output of the driver is controlled, the high-voltage output terminal of the driver is connected to the control terminal of first electric switch, institute
The low-voltage output end for stating driver is connected to the control terminal of second electric switch, the first end connection of first electric switch
To voltage input end, the second end of first electric switch is connected to the first end of second electric switch, and described second establishes by cable
The second end of pass is grounded, and the node between first electric switch and second electric switch is connected to voltage output end, described
Voltage output end is connected to the liquid crystal display panel, first pwm signal with and the second pwm signal polarity it is opposite.
Wherein, the power circuit further includes inductance and the second capacitor, and the first end of the inductance is connected to described first
On node between electric switch and the second electric switch, the second end of the inductance is connected to by second capacity earth
The voltage output end.
Wherein, the power circuit further includes the 4th resistance, third capacitor and the 4th capacitor, and the 4th resistance is connected to
Between the second end of the first switch and the inverting input terminal of the first comparator, the third capacitance connection is described
Between the second end and ground of one switch, the 4th capacitance connection is between the inverting input terminal and ground of the first comparator.
Wherein, the power circuit further includes phase inverter, and the input terminal of the phase inverter receives first pwm signal,
The output end of the phase inverter is connected to the second switch, and the 2nd PWM letter is obtained after the first pwm signal is negated
Number, so that second pwm signal controls the second switch closing or opening.
The embodiment of the present invention have the following advantages that or the utility model has the advantages that
A kind of power circuit of the invention is applied in liquid crystal display, and the power circuit includes the first current source, the
Two current sources, first switch, second switch, first comparator, the second comparator, latch, driver, first resistor, second
Resistance, 3rd resistor, first capacitor, the first electric switch and the second electric switch, first current source are connected to described first and open
The first end of pass, to provide the first electric current, the second end of the first switch is grounded by the first resistor, and described first opens
Pass is controlled by the first pwm signal, and second current source is grounded by the first capacitor, to provide the second electric current, described
The anode and cathode of two current sources is connected to voltage input end by the rate converter, so that the second electric current is defeated according to the voltage
Enter the voltage change of end input and change, the inverting input terminal of the first comparator is connected to the first switch and described the
Node between one resistance, the non-inverting input terminal of the first comparator are connected to second current source and the first capacitor
Between node, and be grounded by the second switch, the second switch is controlled by the second pwm signal, and described first compares
The output end of device is connected to the end R of the latch, and the end S of the latch is connected to the output end of second comparator,
The second resistance and the 3rd resistor are connected between voltage output end and ground, the inverting input terminal of second comparator
The non-inverting input terminal of the node being connected between the second resistance and the 3rd resistor, second comparator receives reference
The output end of voltage, the latch is connected to driver, to control the output of the driver, the high voltage of the driver
Output end is connected to the control terminal of first electric switch, and the low-voltage output end of the driver is connected to described second and establishes by cable
The control terminal of pass, the first end of first electric switch are connected to voltage input end, the second end connection of first electric switch
To the first end of second electric switch, the second end ground connection of second electric switch, first electric switch and described second
Node between electric switch is connected to voltage output end, the voltage output end connection load, first pwm signal and and institute
It is opposite to state the second pwm signal polarity.Therefore, the rate converter makes second electric current and input voltage proportional, it is ensured that
The line regulation of the power circuit is effectively improved, thus guarantee be using the liquid crystal display of the power circuit
System stability.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is a kind of circuit diagram for power circuit that first aspect of the present invention embodiment provides；
Fig. 2 is a kind of block diagram for liquid crystal display that second aspect of the present invention embodiment provides.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiment is only a part of the embodiments of the present invention, instead of all the embodiments.Base
Embodiment in the present invention, those of ordinary skill in the art are obtained all without making creative work
Other embodiments shall fall within the protection scope of the present invention.
In addition, the explanation of following embodiment is referred to the additional illustration, the spy that can be used to implement to illustrate the present invention
Determine embodiment.Direction terms mentioned in the present invention, for example, "upper", "lower", "front", "rear", "left", "right", "inner",
"outside", " side " etc. are only the directions with reference to annexed drawings, and therefore, the direction term used is to more preferably, more clearly say
The bright and understanding present invention, rather than indicate or imply signified device or element and must have a particular orientation, with specific square
Position construction and operation, therefore be not considered as limiting the invention.
In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, term " installation ", " phase
Even ", " connection " shall be understood in a broad sense, for example, it may be fixedly connected, is also possible to detachably connected, or integrally connects
It connects；It can be mechanical connection；It can be directly connected, can also can be in two elements indirectly connected through an intermediary
The connection in portion.For the ordinary skill in the art, the tool of above-mentioned term in the present invention can be understood with concrete condition
Body meaning.
In addition, in the description of the present invention, unless otherwise indicated, the meaning of " plurality " is two or more.If this
Occur the term of " process " in specification, refers not only to independent process, when can not clearly be distinguished with other process, as long as
Effect desired by the process is able to achieve then to be also included in this term.In addition, the numerical value model indicated in this specification with "~"
Enclose the range for referring to that the numerical value for recording "~" front and back is included as minimum value and maximum value.In the accompanying drawings, structure
Similar or identical is indicated by the same numeral.
Referring to Fig. 1, first aspect of the present invention embodiment provides a kind of power circuit 100.The power circuit 100 is applied
In liquid crystal display, to provide operating voltage for the liquid crystal display panel of liquid crystal display.The power circuit 100 includes the first electricity
Stream source A1, the second current source A2, first switch K1, second switch K2, first comparator U1, the second comparator U2, latch SR,
Driver D, first resistor R1, second resistance R2,3rd resistor R3, first capacitor C1, the first electric switch Q1, the second electric switch Q2
And rate converter Z.The first current source A1 is connected to the first end of the first switch K1, to provide the first electric current, institute
The second end for stating first switch K2 is grounded by the first resistor R1, and the first switch K is controlled by the first pwm signal, institute
It states the second current source A2 to be grounded by the first capacitor C1, to provide the second electric current, the anode and cathode of the second current source A2
It is connected to voltage input end Vin by the rate converter Z, so that the electricity that the second electric current is inputted according to the voltage input end
Buckling and change, the inverting input terminal of the first comparator U1 is connected to the first switch K1 and the first resistor R1
Between node, the non-inverting input terminal of the first comparator U is connected to the second current source A2 and the first capacitor C1
Between node, and be grounded by the second switch K2, the second switch K2 is controlled by the second pwm signal, described first
The output end of comparator U1 is connected to the end R of the latch SR, and the end S of the latch SR is connected to second comparator
The output end of U2, the second resistance R2 and the 3rd resistor R3 are connected between voltage output end VO and ground, and described second
The inverting input terminal of comparator U2 is connected to the node between the second resistance R2 and the 3rd resistor R3, second ratio
Non-inverting input terminal compared with device U2 receives reference voltage Vref, and the output end G of the latch SR is connected to driver D, with control
The output of the driver D, the high-voltage output terminal UG of the driver D are connected to the control terminal of the first electric switch Q1,
The low-voltage output end LG of the driver D is connected to the control terminal of the second electric switch Q2, the first electric switch Q1's
First end is connected to voltage input end Vin, and the second end of the first electric switch Q1 is connected to the of the second electric switch Q2
One end, the second end ground connection of the second electric switch Q2, the section between the first electric switch Q1 and the second electric switch Q2
Point is connected to voltage output end VO, first pwm signal with and the second pwm signal polarity it is opposite.
It should be noted that passing through the partial pressure electricity for detecting the node between the second resistance R2 and 3rd resistor R3
FB is pressed, the voltage condition of the voltage output end VO can be reflected.The power circuit 100 is also DC-DC conversion circuit.
Wherein, when the branch pressure voltage FB voltage is less than the reference voltage Vref, the output of the second comparator U2
End output high level, i.e. pin=1 S of latch SR, the output end Q of the latch SR is for exporting the first PWM letter
Number, at this point, the output end Q exports high level signal.The high-voltage output terminal UG of the driver D is high level.Described
One electric switch Q1 closure, the voltage that the voltage of the voltage output end VO output of the power circuit is the voltage input end Vin.
Meanwhile the first switch K1 is closed, the voltage V1=i*R1*D at the inverting input terminal of the second comparator U2, wherein i
For first electric current, R1 is the resistance value of the first resistor R1.D is the duty ratio of the first pwm signal.Therefore, described second
Voltage V1 at the inverting input terminal of comparator U2 is fixed value.The second switch K2 is disconnected, and the first capacitor C1 starts
It charges, the voltage of the voltage V2 at the non-inverting input terminal of the second comparator U2 is begun to ramp up.Wherein, V2=i*Ton/C1,
Wherein, the i is second electric current, and is equal to first electric current, and C1 is the capacitance of the first capacitor C1, and Ton is institute
State the turn-on time of the first pwm signal.The rising of the voltage of voltage V2 at the non-inverting input terminal of the second comparator U2 is oblique
Rate is fixed.When the voltage V2 rises to equal to the voltage V1, the R pin of the latch SR is 1, the latch SR
Output end Q export low level.The second switch K2 ground connection, the voltage V2 pull down to ground.Voltage V2=voltage V1 reaches
Peak value.Since voltage V1 is fixed, the rate of rise of voltage V2 is fixed, and therefore, the high level time of first pwm signal is solid
It is fixed.Therefore work as load to become larger suddenly, the output voltage and second resistance R2 and third of the voltage output end VO of the power circuit
When node voltage FB between resistance R3 declines, the frequency of first pwm signal becomes faster, so that load response becomes faster, with true
The voltage fluctuation for protecting the voltage output end VO output of the power circuit 100 is smaller, promotes the liquid of the application power circuit 100
The system stability of crystal display.
In addition, the present embodiment is by increasing a rate converter for keeping the second electric current i1 proportional to input voltage vin
Z, when input voltage vin variation, the second electric current i1 is followed, so that the high level turn-on time Ton of the first pwm signal can be fast
Speed follows input voltage vin to change, and guarantees that output voltage VO will not fluctuate greatly, lifting system stability.
For example, then the second electric current i1 will increase to i2 from i1 when input voltage vin increases to Vin2 from Vin1, and
I2=Vin2/Vin1*i1, thus Ton2=Vin1/Vin2*Ton1, and Ton2 reduces, and may insure to work as input voltage in this way
When Vin becomes larger very much, the output voltage fluctuation will not be very big, to guarantee the liquid crystal display using the power circuit 100
The system stability of device.
Similarly, when input voltage vin is reduced to Vin2 from Vin1, then the second electric current i1 will be reduced to i2 from i1,
And i2=Vin2/Vin1*i1, thus Ton2=Vin1/Vin2*Ton1, and Ton2 increases, and may insure to work as input voltage in this way
When Vin becomes smaller very much, the output voltage fluctuation will not be very big, to guarantee the liquid crystal display using the power circuit 100
The system stability of device.
Therefore, in the present embodiment, increase the rate converter Z in this way and allow the second electric current i1 and input voltage
Vin is proportional, it is ensured that the line regulation of the power circuit 100 is effectively improved, to guarantee using the power supply electricity
The system stability of the liquid crystal display on road 100.
Further, the power circuit 100 further includes inductance L and the second capacitor C2.The first end of the inductance L connects
On node between the first electric switch K1 and the second electric switch K2, the second end of the inductance L passes through second electricity
Hold C2 ground connection, and is connected to the voltage output end VO.
The power circuit 100 further includes the 4th resistance R4, third capacitor C3 and the 4th capacitor C4, the 4th resistance R4
It is connected between the second end of the first switch K1 and the inverting input terminal of the first comparator U1, the third capacitor C3
It is connected between the second end and ground of the first switch K1, the 4th capacitor C4 is connected to the anti-of the first comparator U1
Between phase input terminal and ground.
Specifically, the power circuit 100 further includes phase inverter N.The input terminal of the phase inverter N receives described first
Pwm signal, the output end of the phase inverter N are connected to the second switch K2, obtain after the first pwm signal is negated
Second pwm signal, so that second pwm signal controls being turned on or off for the second switch K2.
In the present embodiment, the phase inverter N is NOT gate.
Further, the power circuit 100 further includes diode D1, and the anode of the diode D1 is connected to described
One current source A1 cathode, the cathode of the diode D1 are connected to the anode of the first current source A1.
In the present embodiment, the first electric switch Q1 and the second electric switch Q2 are N-type field-effect tube, and described the
Control terminal, first end and the second end of one electric switch Q1 and the second electric switch Q2 are respectively the grid of field-effect tube, drain electrode
And source electrode.In other embodiments, the type of the first electric switch Q1 and the second electric switch Q2 can also be according to reality
Situation replacement.
Referring to Fig. 2, second aspect of the present invention embodiment provides a kind of liquid crystal display 200.The liquid crystal display 200
The power circuit of operating voltage is provided including liquid crystal display panel 210 and for the liquid crystal display panel 210.The power circuit is above-mentioned the
Power circuit 100 in one scheme.Specifically:
The power circuit 100 includes the first current source A1, the second current source A2, first switch K1, second switch K2, the
One comparator U1, the second comparator U2, latch SR, driver D, first resistor R1, second resistance R2,3rd resistor R3,
One capacitor C1, the first electric switch Q1 and the second electric switch Q2.The first current source A1 is connected to the of the first switch K1
One end, to provide the first electric current, the second end of the first switch K2 is grounded by the first resistor R1, the first switch
K is controlled by the first pwm signal, and the second current source A2 is grounded by the first capacitor C1, described to provide the second electric current
The inverting input terminal of first comparator U1 is connected to the node between the first switch K1 and the first resistor R1, and described
The non-inverting input terminal of one comparator U is connected to the node between the second current source A2 and the first capacitor C1, and passes through
The second switch K2 ground connection, the second switch K2 are controlled by the second pwm signal, and the output end of the first comparator U1 connects
It is connected to the end R of the latch SR, the end S of the latch SR is connected to the output end of the second comparator U2, and described
Two resistance R2 and the 3rd resistor R3 are connected between voltage output end VO and ground, the anti-phase input of the second comparator U2
End is connected to the node between the second resistance R2 and the 3rd resistor R3, the non-inverting input terminal of the second comparator U2
Reference voltage Vref is received, the output end G of the latch SR is connected to driver D, to control the output of the driver D,
The high-voltage output terminal UG of the driver D is connected to the control terminal of the first electric switch Q1, the low-voltage of the driver D
Output end LG is connected to the control terminal of the second electric switch Q2, and the first end of the first electric switch Q1 is connected to voltage input
Vin is held, the second end of the first electric switch Q1 is connected to the first end of the second electric switch Q2, the second electric switch Q2
Second end ground connection, the node between the first electric switch Q1 and the second electric switch Q2 is connected to voltage output end VO,
The voltage output end VO is connected to the liquid crystal display panel 210, first pwm signal and and the second pwm signal polarity
On the contrary.
It should be noted that passing through the partial pressure electricity for detecting the node between the second resistance R2 and 3rd resistor R3
FB is pressed, the voltage condition of the voltage output end VO can be reflected.The power circuit 100 is also DC-DC conversion circuit.
Wherein, when the branch pressure voltage FB voltage is less than the reference voltage Vref, the output of the second comparator U2
End output high level, i.e. pin=1 S of latch SR, the output end Q of the latch SR is for exporting the first PWM letter
Number, at this point, the output end Q exports high level signal.The high-voltage output terminal UG of the driver D is high level.Described
One electric switch Q1 closure, the voltage that the voltage of the voltage output end VO output of the power circuit is the voltage input end Vin.
Meanwhile the first switch K1 is closed, the voltage V1=i*R1*D at the inverting input terminal of the second comparator U2, wherein i
For first electric current, R1 is the resistance value of the first resistor R1.D is the duty ratio of the first pwm signal.Therefore, described second
Voltage V1 at the inverting input terminal of comparator U2 is fixed value.The second switch K2 is disconnected, and the first capacitor C1 starts
It charges, the voltage of the voltage V2 at the non-inverting input terminal of the second comparator U2 is begun to ramp up.Wherein, V2=i*Ton/C1,
Wherein, the i is second electric current, and is equal to first electric current, and C1 is the capacitance of the first capacitor C1, and Ton is institute
State the turn-on time of the first pwm signal.The rising of the voltage of voltage V2 at the non-inverting input terminal of the second comparator U2 is oblique
Rate is fixed.When the voltage V2 rises to equal to the voltage V1, the R pin of the latch SR is 1, the latch SR
Output end Q export low level.The second switch K2 ground connection, the voltage V2 pull down to ground.Voltage V2=voltage V1 reaches
Peak value.Since voltage V1 is fixed, the rate of rise of voltage V2 is fixed, and therefore, the high level time of first pwm signal is solid
It is fixed.Therefore work as load to become larger suddenly, the output voltage and second resistance R2 and third of the voltage output end VO of the power circuit
When node voltage FB between resistance R3 declines, the frequency of first pwm signal becomes faster, so that load response becomes faster, with true
The voltage fluctuation for protecting the voltage output end VO output of the power circuit is smaller, and the system for promoting the liquid crystal display 200 is steady
It is qualitative.
In addition, the present embodiment is by increasing a rate converter for keeping the second electric current i1 proportional to input voltage vin
Z, when input voltage vin variation, the second electric current i1 is followed, so that the high level turn-on time Ton of the first pwm signal can be fast
Speed follows input voltage vin to change, and guarantees that output voltage VO will not fluctuate greatly, lifting system stability.
For example, then the second electric current i1 will increase to i2 from i1 when input voltage vin increases to Vin2 from Vin1, and
I2=Vin2/Vin1*i1, thus Ton2=Vin1/Vin2*Ton1, and Ton2 reduces, and may insure to work as input voltage in this way
When Vin becomes larger very much, the output voltage fluctuation will not be very big, to guarantee the liquid crystal display using the power circuit 100
The system stability of device.
Similarly, when input voltage vin is reduced to Vin2 at Vin1, then the second electric current i1 will be reduced to i2 at i1,
And i2=Vin2/Vin1*i1, thus Ton2=Vin1/Vin2*Ton1, and Ton2 increases, and may insure to work as input voltage in this way
When Vin becomes smaller very much, the output voltage fluctuation will not be very big, to guarantee the liquid crystal display using the power circuit 100
The system stability of device.
Therefore, in the present embodiment, increase the rate converter Z in this way and allow the second electric current i1 and input voltage
Vin is proportional, it is ensured that the line regulation of the power circuit 100 is effectively improved, to guarantee using the power supply electricity
The system stability of the liquid crystal display on road 100.
Further, the power circuit 100 further includes inductance L and the second capacitor C2.The first end of the inductance L connects
On node between the first electric switch K1 and the second electric switch K2, the second end of the inductance L passes through second electricity
Hold C2 ground connection, and is connected to the voltage output end VO.
The power circuit 100 further includes the 4th resistance R4, third capacitor C3 and the 4th capacitor C4, the 4th resistance R4
It is connected between the second end of the first switch K1 and the inverting input terminal of the first comparator U1, the third capacitor C3
It is connected between the second end and ground of the first switch K1, the 4th capacitor C4 is connected to the anti-of the first comparator U1
Between phase input terminal and ground.
Specifically, the power circuit 100 further includes phase inverter N.The input terminal of the phase inverter N receives described first
Pwm signal, the output end of the phase inverter N are connected to the second switch K2, obtain after the first pwm signal is negated
Second pwm signal, so that second pwm signal controls being turned on or off for the second switch K2.
In the present embodiment, the phase inverter N is NOT gate.
Further, the power circuit 100 further includes diode D1, and the anode of the diode D1 is connected to described
One current source A1 cathode, the cathode of the diode D1 are connected to the anode of the first current source A1.
In the present embodiment, the first electric switch Q1 and the second electric switch Q2 are N-type field-effect tube, and described the
Control terminal, first end and the second end of one electric switch Q1 and the second electric switch Q2 are respectively the grid of field-effect tube, drain electrode
And source electrode.In other embodiments, the type of the first electric switch Q1 and the second electric switch Q2 can also be according to reality
Situation replacement.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show
The description of example " or " some examples " etc. means particular features, structures, materials, or characteristics described in conjunction with this embodiment or example
It is included at least one embodiment or example of the invention.In the present specification, schematic expression of the above terms are different
Surely identical embodiment or example is referred to.Moreover, the particular features, structures, materials, or characteristics of description can be any one
It can be combined in any suitable manner in a or multiple embodiment or examples.
Embodiments described above does not constitute the restriction to the technical solution protection scope.It is any in above-mentioned implementation
Made modifications, equivalent substitutions and improvements etc., should be included in the protection model of the technical solution within the spirit and principle of mode
Within enclosing.
Claims (10)
1. a kind of power circuit, be applied in liquid crystal display, it is characterised in that: the power circuit include the first current source,
Second current source, first switch, second switch, first comparator, the second comparator, latch, driver, first resistor,
Two resistance, 3rd resistor, first capacitor, the first electric switch, the second electric switch and rate converter, the first current source connection
To the first end of the first switch, to provide the first electric current, the second end of the first switch is connect by the first resistor
Ground, the first switch are controlled by the first pwm signal, and second current source is grounded by the first capacitor, to provide
The anode and cathode of two electric currents, second current source is connected to voltage input end by the rate converter, so that the second electric current
Changed according to the voltage change of voltage input end input, the inverting input terminal of the first comparator is connected to described the
Node between one switch and the first resistor, the non-inverting input terminal of the first comparator are connected to second current source
It with the node between the first capacitor, and is grounded by the second switch, the second switch is controlled by the 2nd PWM letter
Number, the output end of the first comparator is connected to the end R of the latch, and the end S of the latch is connected to described second
The output end of comparator, the second resistance and the 3rd resistor are connected between voltage output end and ground, second ratio
Be connected to the node between the second resistance and the 3rd resistor compared with the inverting input terminal of device, second comparator it is same
Phase input terminal receives reference voltage, and the output end of the latch is connected to driver, to control the output of the driver, institute
The high-voltage output terminal for stating driver is connected to the control terminal of first electric switch, and the low-voltage output end of the driver connects
It is connected to the control terminal of second electric switch, the first end of first electric switch is connected to voltage input end, first electricity
The second end of switch is connected to the first end of second electric switch, and the second end of second electric switch is grounded, and described first
Node between electric switch and second electric switch is connected to voltage output end, first pwm signal and and described second
Pwm signal polarity is on the contrary, the second current following variation described in when the voltage change of voltage input end input, and described first
The high level turn-on time of pwm signal can rapidly follow the voltage change of the voltage input end input, guarantee described defeated
Voltage fluctuation is small out.
2. power circuit as described in claim 1, which is characterized in that the power circuit further includes inductance and the second capacitor,
The first end of the inductance is connected on the node between first electric switch and the second electric switch, the second end of the inductance
By second capacity earth, and it is connected to the voltage output end.
3. power circuit as claimed in claim 1 or 2, which is characterized in that the power circuit further includes the 4th resistance, third
The reverse phase of capacitor and the 4th capacitor, second end and the first comparator that the 4th resistance is connected to the first switch is defeated
Enter between end, the third capacitance connection is between the second end and ground of the first switch, and the 4th capacitance connection is in institute
It states between the inverting input terminal of first comparator and ground.
4. power circuit as claimed in claim 3, which is characterized in that the power circuit further includes phase inverter, the reverse phase
The input terminal of device receives first pwm signal, and the output end of the phase inverter is connected to the second switch, by first
Pwm signal obtains the second pwm signal after being negated, so that second pwm signal controls the second switch closure or disconnected
It opens.
5. power circuit as claimed in claim 4, which is characterized in that the power circuit further includes diode, two pole
The anode of pipe is connected to first current source negative pole, and the cathode of the diode is connected to the anode of first current source.
6. power circuit as claimed in claim 1 or 2, which is characterized in that first electric switch and second electric switch
It is N-type field-effect tube, control terminal, first end and the second end of first electric switch and second electric switch are respectively field
Grid, drain electrode and the source electrode of effect pipe.
7. a kind of liquid crystal display provides the power circuit of operating voltage including liquid crystal display panel and for the liquid crystal display panel, described
Power circuit includes the first current source, the second current source, first switch, second switch, first comparator, the second comparator, lock
Storage, driver, first resistor, second resistance, 3rd resistor, first capacitor, the first electric switch, the second electric switch and ratio turn
Parallel operation, first current source are connected to the first end of the first switch, to provide the first electric current, the of the first switch
Two ends are grounded by the first resistor, and the first switch is controlled by the first pwm signal, and second current source passes through described
First capacitor ground connection, to provide the second electric current, the anode and cathode of second current source is connected to electricity by the rate converter
Input terminal is pressed, so that the second electric current changes according to the voltage change that the voltage input end inputs, the first comparator
Inverting input terminal is connected to the node between the first switch and the first resistor, the homophase input of the first comparator
End is connected to node between second current source and the first capacitor, and is grounded by the second switch, and described the
Two switches are controlled by the second pwm signal, and the output end of the first comparator is connected to the end R of the latch, the latch
The end S of device is connected to the output end of second comparator, and the second resistance and the 3rd resistor are connected on voltage output
Between end and ground, the inverting input terminal of second comparator is connected to the section between the second resistance and the 3rd resistor
The non-inverting input terminal of point, second comparator receives reference voltage, and the output end of the latch is connected to driver, with control
The output of the driver is made, the high-voltage output terminal of the driver is connected to the control terminal of first electric switch, described
The low-voltage output end of driver is connected to the control terminal of second electric switch, and the first end of first electric switch is connected to
Voltage input end, the second end of first electric switch are connected to the first end of second electric switch, second electric switch
Second end ground connection, the node between first electric switch and second electric switch is connected to voltage output end, described the
One pwm signal with and the second pwm signal polarity on the contrary, when voltage input end input voltage change when described in the second electric current
Variation is followed, and the high level turn-on time of first pwm signal can rapidly follow the voltage input end to input
Voltage change, guarantee that output voltage fluctuation is small.
8. liquid crystal display as claimed in claim 7, which is characterized in that the power circuit further includes inductance and the second electricity
To hold, the first end of the inductance is connected on the node between first electric switch and the second electric switch, and the of the inductance
Two ends are connected to the voltage output end by second capacity earth.
9. liquid crystal display as claimed in claim 7 or 8, which is characterized in that the power circuit further includes the 4th resistance,
Three capacitors and the 4th capacitor, the 4th resistance are connected to the second end of the first switch and the reverse phase of the first comparator
Between input terminal, between the second end and ground of the first switch, the 4th capacitance connection exists the third capacitance connection
Between the inverting input terminal and ground of the first comparator.
10. liquid crystal display as claimed in claim 9, which is characterized in that the power circuit further includes phase inverter, described anti-
The input terminal of phase device receives first pwm signal, and the output end of the phase inverter is connected to the second switch, by first
Pwm signal obtains the second pwm signal after being negated, so that second pwm signal controls the second switch closure or disconnected
It opens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201611189682.0A CN106712509B (en) | 2016-12-21 | 2016-12-21 | A kind of power circuit and liquid crystal display |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201611189682.0A CN106712509B (en) | 2016-12-21 | 2016-12-21 | A kind of power circuit and liquid crystal display |
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| CN106712509B true CN106712509B (en) | 2019-07-23 |
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| CN201611189682.0A Active CN106712509B (en) | 2016-12-21 | 2016-12-21 | A kind of power circuit and liquid crystal display |
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| CN107171536B (en) * | 2017-06-13 | 2019-11-05 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and switch converters |
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|---|---|---|---|---|
| CN102331810A (en) * | 2011-07-18 | 2012-01-25 | 西安民展微电子有限公司 | Alternative circuit of current sensing power metal oxide semiconductor field effect transistor (MOSFET) |
| CN102360541A (en) * | 2011-10-12 | 2012-02-22 | 友达光电股份有限公司 | Power switching circuit |
| CN104238702A (en) * | 2013-06-07 | 2014-12-24 | 鸿富锦精密工业（深圳）有限公司 | Power supply circuit |
| CN104917376A (en) * | 2014-03-11 | 2015-09-16 | 精工电子有限公司 | Dc/dc converter |
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2016
- 2016-12-21 CN CN201611189682.0A patent/CN106712509B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102331810A (en) * | 2011-07-18 | 2012-01-25 | 西安民展微电子有限公司 | Alternative circuit of current sensing power metal oxide semiconductor field effect transistor (MOSFET) |
| CN102360541A (en) * | 2011-10-12 | 2012-02-22 | 友达光电股份有限公司 | Power switching circuit |
| CN104238702A (en) * | 2013-06-07 | 2014-12-24 | 鸿富锦精密工业（深圳）有限公司 | Power supply circuit |
| CN104917376A (en) * | 2014-03-11 | 2015-09-16 | 精工电子有限公司 | Dc/dc converter |
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