CN208111043U - Switching circuit and backlight drive circuit - Google Patents
Switching circuit and backlight drive circuit Download PDFInfo
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- CN208111043U CN208111043U CN201820547014.9U CN201820547014U CN208111043U CN 208111043 U CN208111043 U CN 208111043U CN 201820547014 U CN201820547014 U CN 201820547014U CN 208111043 U CN208111043 U CN 208111043U
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Abstract
Disclose a kind of switching circuit and backlight drive circuit, wherein switching circuit includes：First enabled circuit generates the first enable signal when input voltage is in preset range for receiving input voltage；Reduction voltage circuit is connected with the first enabled circuit, for providing the first output voltage according to input voltage and sampled signal when receiving the first enable signal；Sample circuit is connected with reduction voltage circuit, for being sampled the first output voltage to provide sampled signal；Second enabled circuit, is connected with sample circuit, and the second enable signal is generated when for not receiving sampled signal；And load switching circuit, it is connected with the second enabled circuit, for providing the second output voltage according to input voltage, realizing the switching without intermediate region neutral gear when receiving the second enable signal.
Description
Technical field
The utility model relates to backlight drive field, relate more specifically to a kind of switching circuit and backlight drive circuit.
Background technique
Since liquid crystal display device has many advantages, such as frivolous, energy saving, low-power consumption, TV, computer, hand have been widely used in it
In the electronic equipments such as machine, digital camera.
Liquid crystal has anisotropic characteristics refractive index, dielectric constant etc., and liquid crystal display device uses the electricity of liquid crystal
And optical characteristics, show image by picture element matrix.Each pixel of liquid crystal display device is by using liquid crystal aligning direction
The optical transmittance relative to polarizing film is adjusted according to the variation of data-signal, realizes gray level.Liquid crystal display device is quilt
Dynamic display device, therefore traditional liquid crystal display device has backlight module, driving circuit is used for the back of liquid crystal display device
The power supply of light lamp.
By taking pocket pc as an example, existing liquid crystal display device can be used adapter power supply or be supplied by battery
Electricity, because battery power supply is different with the voltage swing provided when adapter power supply, existing liquid crystal display device needs
Add switching circuit before driving circuit for driving backlight.
Fig. 1 shows the structural schematic diagram of existing switching circuit.As shown in Figure 1, switching circuit 100 includes the first enabled electricity
Road 110, load switching circuit 120, the second enabled circuit 130, reduction voltage circuit 140 and sample circuit 150.
Load switching circuit 120 includes load switch chip 121 and peripheral circuit connected to it, wherein load switch
Single channel load switch chip TPS22810 can be used in chip 121.Reduction voltage circuit 140 include decompression conversion chip 141 and
Peripheral circuit connected to it, wherein synchronous buck conversion chip TPS54202 can be used in decompression conversion chip 141.
First enabled circuit 110 include first resistor R1 and second resistance R2 composition bleeder circuit, 3rd resistor R3 with
And first switch tube M1.First resistor R1 and second resistance R2 are series between input voltage vin and ground.3rd resistor R3 and
One switching tube M1 is series between power source voltage Vcc and ground, the control terminal and first resistor R1 of first switch tube M1 and the second electricity
The intermediate node for hindering R2 is connected, the first path terminal of first switch tube M1 and the intermediate node of 3rd resistor R3 and load switch core
The enable end EN of piece 121 is connected, for providing the first enable signal.
Second enabled circuit 130 includes the 6th resistance R6 and the 7th resistance R7 being series between input voltage vin and ground,
The intermediate node of 6th resistance R6 and the 7th resistance R7 is connected with the enable end EN of decompression conversion chip 141, for that will input electricity
Press Vin partial pressure to obtain the second enable signal.
Sample circuit 150 includes the 8th resistance R8 and the 9th being series between decompression 141 output end of conversion chip and ground
The intermediate node of resistance R9, the 8th resistance R8 and the 9th resistance R9 are connected with the feedback end FB of decompression conversion chip 141.
The switching circuit 100 of the prior art includes the first enabled circuit 110 and the second enabled circuit 130, by input
Voltage Vin carries out electric resistance partial pressure to select through load switching circuit 120 or reduction voltage circuit 140.But for existing skill
The switching circuit 100 of art, there are the neutral gears of intermediate region for electric resistance partial pressure, when being that adapter is powered from battery power switching, drop
Volt circuit 140 may be in heavy duty, lead to the starting failure of reduction voltage circuit 140.
Therefore, it is necessary to be improved to the switching circuit of the prior art so that switching circuit is when input voltage changes
No neutral gear switching may be implemented.
Utility model content
In view of this, the purpose of this utility model is to provide a kind of switching circuit and including the backlight of the switching circuit
Driving circuit can be realized when input voltage changes and switch without neutral gear.
A kind of switching circuit that one side according to the present utility model provides, including：First enabled circuit, it is defeated for receiving
Enter voltage, generates the first enable signal when input voltage is in preset range；Reduction voltage circuit, with the described first enabled circuit phase
Connection, for providing the first output voltage according to input voltage and sampled signal when receiving first enable signal；It adopts
Sample circuit is connected with the reduction voltage circuit, for being sampled first output voltage to provide sampled signal；Second makes
Energy circuit, being connected with the sample circuit, the second enable signal is generated when for not receiving sampled signal；And load switch
Circuit is connected with the described second enabled circuit, for providing second according to input voltage when receiving second enable signal
Output voltage.
Preferably, the described first enabled circuit includes：The first resistor being series between the input voltage and ground and
The intermediate node of two resistance, the first resistor and second resistance provides first enable signal.
Preferably, the reduction voltage circuit includes：First capacitor and the second capacitor；It is depressured conversion chip, the decompression conversion
The power voltage input terminal of chip receives the input voltage and is connected to ground, enable signal end and institute via the first capacitor
The first enabled circuit to be stated to be connected to receive second enable signal, feedback signal input terminal receives the sampled signal, and first
Output end is connected with second output terminal via second capacitor；Inductance coil, the first end of the inductance coil and the drop
The second output terminal of conversion chip is pressed to be connected, second end provides second output voltage.
Preferably, the sample circuit includes the 3rd resistor being series between the inductance coil second end and ground and
Four resistance, the node between the 3rd resistor and the 4th resistance provide the sampled signal, the 3rd resistor and the 4th electricity
Node between resistance is connected with the feedback signal input terminal of the decompression conversion chip.
Preferably, the described second enabled circuit includes：The 5th resistance and the switching tube being series between supply voltage and ground,
The control terminal of the switching tube is connected to receive the sampled signal, the switching tube and the 5th electricity with the sample circuit
Node between resistance provides second enable signal.
Preferably, the load switching circuit includes：6th resistance；Load switch chip, the load switch chip
Power voltage input terminal receives the input voltage, the node between enable signal end and the switching tube and the 5th resistance
It is connected to receive second enable signal, output end is connected with repid discharge end via the 6th resistance；4th capacitor, string
It is coupled between the power voltage input terminal and ground of the load switch chip；And the 5th capacitor and the 7th resistance, it is in parallel
Between the output end and ground connection of the load switch chip.
Preferably, switching circuit further includes：Output circuit is connected to reduction voltage circuit and load switching circuit, for exporting
The first output voltage provided by reduction voltage circuit or the second output voltage provided by load switching circuit.
Preferably, the output circuit includes：Diode, the first end of the diode be connected with the reduction voltage circuit with
First output voltage is received, second end is connected to receive second output voltage with the load switching circuit；Filtering
Capacitor is series between the second end and ground of the diode.
Another aspect according to the present utility model provides a kind of backlight drive circuit, including：Above-mentioned switching circuit, and
The post-stage drive circuit being attached thereto, the driving circuit receives the output voltage that the switching circuit provides, according to described defeated
Voltage drives backlight display out.
Switching circuit provided by the utility model and the beneficial effect of backlight drive circuit are to open in reduction voltage circuit
When dynamic, effective sampled signal is provided from sample circuit to the second enabled circuit, load switching circuit is closed, realizes without middle area
The switching of domain neutral gear.Also, for switching circuit provided by the utility model, if reduction voltage circuit does not work, load switching circuit
It can work normally, avoid the damage caused by circuit of reduction voltage circuit heavy duty work.
Detailed description of the invention
By referring to the drawings to the description of the utility model embodiment, above-mentioned and other mesh of the utility model
, feature and advantage will be apparent from.
Fig. 1 shows the structural schematic diagram of existing switching circuit.
Fig. 2 shows the structural schematic diagrams of the switching circuit of the utility model embodiment.
Fig. 3 shows the circuit diagram of the switching circuit of the utility model embodiment.
Fig. 4 shows the simulation schematic diagram of the switching circuit of the utility model embodiment.
Specific embodiment
Hereinafter reference will be made to the drawings is more fully described the utility model.In various figures, identical element is using similar
Appended drawing reference indicate.For the sake of clarity, the various pieces in attached drawing are not necessarily to scale.In addition, may in figure
Certain well known parts are not shown.
Many specific details of the utility model, such as the structure of component, material, size, place are described hereinafter
Science and engineering skill and technology, to be more clearly understood that the utility model.But just as the skilled person will understand,
The utility model can not be realized according to these specific details.
Fig. 2 shows the structural schematic diagrams of the switching circuit of the utility model.As shown in Fig. 2, provided by the utility model cut
Changing circuit 200 includes the first enabled circuit 210, reduction voltage circuit 220, sample circuit 230, the second enabled circuit 240 and load
Switching circuit 250.First enabled circuit 210 receives input voltage vin, input voltage vin within a preset range when generate the
One enable signal.Reduction voltage circuit 220 is connected with the first enabled circuit 210, for when receiving the first enable signal, according to defeated
Enter voltage Vin and sampled signal provides the first output voltage.Sample circuit 230 is connected with reduction voltage circuit 220, for output electricity
Pressure Vout is sampled to obtain sampled signal.
Second enabled circuit 240 is connected with sample circuit 230, enabled for generating second when not receiving sampled signal
Signal.Load switching circuit 250 is connected with the second enabled circuit 240, for when receiving the second enable signal according to input
Voltage Vin provides the second output voltage.
Fig. 3 shows the circuit diagram of the switching circuit of the utility model embodiment.As shown in figure 3, load switching circuit
250 include load switch chip 251 and peripheral circuit connected to it, wherein single-pass can be used in load switch chip 251
Road load switch chip TPS22810.Reduction voltage circuit 220 includes being depressured conversion chip 221 and peripheral circuit connected to it,
Wherein, synchronous buck conversion chip TPS54202 can be used in decompression conversion chip 221.Certainly, the load of the utility model is opened
It closes chip 251 and decompression conversion chip 221 is not limited thereto system, those skilled in the art can select as the case may be
The type of chip.
First enabled circuit 210 includes the first resistor R1 and second resistance R2 being series between input voltage vin and ground,
The intermediate node of first resistor R1 and second resistance R2 are connected with the enable signal end EN of decompression conversion chip 221 to provide first
Enable signal.
Reduction voltage circuit 220 includes decompression conversion chip 221 and first capacitor C1, the second capacitor C2, inductance coil L1.Its
In, the power voltage input terminal VIN of decompression conversion chip 221 receives input voltage vin, and first capacitor C1 is series at decompression conversion
Between the power voltage input terminal VIN and ground terminal GND of chip 221, and it is depressured the ground terminal GND ground connection of conversion chip 221.
The first end of second capacitor C2 is connect with the first output end BOOT of decompression conversion chip 221, second end and decompression conversion chip
221 second output terminal SW is connected.The second of the first end of inductance coil L1 and the second capacitor C2 and decompression conversion chip 221
The intermediate node of output end SW is connected, and second end provides output voltage.
Sample circuit 230 includes the 3rd resistor R3 being connected between decompression 221 output end SW of conversion chip and ground and the
The feedback signal input terminal FB of the intermediate node of four resistance R4,3rd resistor R3 and the 4th resistance R4 and decompression conversion chip 221
It is connected.
Switching circuit 200 further includes output circuit 260, and output circuit 260 is connected to reduction voltage circuit 220 and load switch electricity
Road 250, for exporting the first output voltage provided by reduction voltage circuit 220 or provided by load switching circuit 250 second
Output voltage.Wherein, output circuit 260 includes third capacitor C3 and diode D1, the first end and 3rd resistor of diode D1
R3 is connected with the intermediate node of inductance coil L1, and second end is connected with the output end of output voltage Vout.Third capacitor C3 series connection
Between the output end and ground of output voltage Vout.
Second enabled circuit 240 includes the 5th resistance R5 and the switching tube M1 being series between supply voltage VCC and ground, is opened
The control terminal for closing pipe M1 is connected to receive above-mentioned sampled signal with the intermediate node of 3rd resistor R3 and the 4th resistance R4, switch
The first path terminal of pipe M1 and the intermediate node of the 5th resistance R5 export the second enable signal and open when receiving sampled signal
Pipe M1 conducting is closed, the second enable signal is invalid.
Load switching circuit 250 include load switch chip 251, the 4th capacitor C4, the 5th capacitor C5, the 6th capacitor C6 with
And the 6th resistance R6 and the 7th resistance R7.The first end of 4th capacitor C4 and the power voltage input terminal of load switch chip 251
VIN is connected, second end ground connection.6th resistance R6 is series at the output end VOUT and repid discharge end QOD of load switch chip 251
Between.5th capacitor C5 and the 7th resistance R7 form RC filter circuit, the first end of the 5th capacitor C5 and the 7th resistance R7 with bear
The output end VOUT of load switch chip 251 is connected, second end ground connection.The first end and load switch chip 251 of 6th capacitor C6
Switching rate control terminal CT be connected, second end ground connection.The output end VOUT's and output voltage Vout of load switch chip 251
Output end is connected.
Fig. 4 shows the simulation schematic diagram of the switching circuit of the utility model embodiment.Curve 1 indicates output voltage Vout's
Change curve, curve 2 indicate that the change curve of input voltage vin, curve 3 indicate the change curve of the second enable signal.
As shown in figure 4, output voltage Vout of the switching circuit of the utility model in input voltage vin handoff procedure
Moment is minimum in 6.8V or so, meets the output demand of late-class circuit, there is no the neutral gears of intermediate region.
Another aspect according to the present utility model provides a kind of backlight drive circuit, including above-mentioned switching circuit and with
Connected post-stage drive circuit, driving circuit is used to receive the output voltage of switching circuit offer, driven according to the output voltage
Dynamic backlight display.
In conclusion switching circuit provided by the utility model and backlight drive circuit include reduction voltage circuit, load and open
Powered-down road and sample circuit, sample circuit is for sampling to provide sampling the first output voltage that reduction voltage circuit provides
Signal.Switching circuit provided by the utility model can be provided when reduction voltage circuit starts from sample circuit to the second enabled circuit
Effective sampled signal closes load switching circuit, realizes the switching without intermediate region neutral gear.Also, for the utility model
The switching circuit of offer, if reduction voltage circuit does not work, load switching circuit be can work normally, and avoid reduction voltage circuit heavy duty work
Work is damaged caused by circuit.
It should be noted that herein, relational terms such as first and second and the like are used merely to a reality
Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation
In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to
Non-exclusive inclusion, so that the process, method, article or equipment including a series of elements is not only wanted including those
Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or equipment
Intrinsic element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that
There is also other identical elements in process, method, article or equipment including the element.
It is as described above according to the embodiments of the present invention, these embodiments details all there is no detailed descriptionthe,
Also not limiting the utility model is only the specific embodiment.Obviously, as described above, many modification and change can be made
Change.These embodiments are chosen and specifically described to this specification, is in order to preferably explain the principles of the present invention and actually to answer
With so that skilled artisan be enable to utilize the utility model and repairing on the basis of the utility model well
Change use.The utility model is limited only by the claims and their full scope and equivalents.
Claims (9)
1. a kind of switching circuit, which is characterized in that including：
First enabled circuit generates the first enable signal when input voltage is in preset range for receiving input voltage；
Reduction voltage circuit is connected with the described first enabled circuit, for when receiving first enable signal, according to input
Voltage and sampled signal provide the first output voltage；
Sample circuit is connected with the reduction voltage circuit, for being sampled first output voltage to provide sampled signal；
Second enabled circuit, is connected with the sample circuit, and the second enable signal is generated when for not receiving sampled signal；With
And
Load switching circuit is connected with the described second enabled circuit, is used for when receiving second enable signal, according to input
Voltage provides the second output voltage.
2. switching circuit according to claim 1, which is characterized in that the first enabled circuit includes：
The first resistor and second resistance being series between the input voltage and ground, in the first resistor and second resistance
Intermediate node provides first enable signal.
3. switching circuit according to claim 1, which is characterized in that the reduction voltage circuit includes：
First capacitor and the second capacitor；
It is depressured conversion chip, the power voltage input terminal of the decompression conversion chip receives the input voltage and via described the
To ground, enable signal end is connected with the described first enabled circuit to receive second enable signal, feedback letter one capacitance connection
Number input terminal receives the sampled signal, and the first output end is connected with second output terminal via second capacitor；
Inductance coil, the first end of the inductance coil are connected with the second output terminal of the decompression conversion chip, and second
End provides second output voltage.
4. switching circuit according to claim 3, which is characterized in that the sample circuit includes being series at the inductor wire
The 3rd resistor and the 4th resistance between second end and ground are enclosed, described in the node offer between the 3rd resistor and the 4th resistance
Sampled signal,
Node between the 3rd resistor and the 4th resistance is connected with the feedback signal input terminal of the decompression conversion chip.
5. switching circuit according to claim 1, which is characterized in that the second enabled circuit includes：
The 5th resistance and the switching tube being series between supply voltage and ground, the control terminal of the switching tube and the sample circuit
It is connected to receive the sampled signal,
Node between the switching tube and the 5th resistance provides second enable signal.
6. switching circuit according to claim 5, which is characterized in that the load switching circuit includes：
6th resistance；
The power voltage input terminal of load switch chip, the load switch chip receives the input voltage, enable signal end
Node between the switching tube and the 5th resistance is connected to receive second enable signal, output end with quickly put
Electric end is connected via the 6th resistance；
4th capacitor is series between the power voltage input terminal and ground of the load switch chip；And
5th capacitor and the 7th resistance are connected in parallel between the output end of the load switch chip and ground connection.
7. switching circuit according to claim 1, which is characterized in that further include：Output circuit, be connected to reduction voltage circuit and
Load switching circuit, for exporting the first output voltage provided by reduction voltage circuit or provided by load switching circuit second
Output voltage.
8. switching circuit according to claim 7, which is characterized in that the output circuit includes：
Diode, the first end of the diode are connected to receive first output voltage, second end with the reduction voltage circuit
It is connected with the load switching circuit to receive second output voltage；
Filter capacitor is series between the second end and ground of the diode.
9. a kind of backlight drive circuit, which is characterized in that including：
The described in any item switching circuits of claim 1-8, and
The post-stage drive circuit being attached thereto, the driving circuit receives the output voltage that the switching circuit provides, according to institute
State output voltage driving backlight display.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201820547014.9U CN208111043U (en) | 2018-04-17 | 2018-04-17 | Switching circuit and backlight drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201820547014.9U CN208111043U (en) | 2018-04-17 | 2018-04-17 | Switching circuit and backlight drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN208111043U true CN208111043U (en) | 2018-11-16 |
Family
ID=64118687
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201820547014.9U Active CN208111043U (en) | 2018-04-17 | 2018-04-17 | Switching circuit and backlight drive circuit |
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| Country | Link |
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| CN (1) | CN208111043U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109586397A (en) * | 2018-12-05 | 2019-04-05 | 新华三技术有限公司 | Power control circuit and electronic equipment |
| CN109686322A (en) * | 2019-02-19 | 2019-04-26 | 昆山龙腾光电有限公司 | Switching circuit and backlight drive circuit |
| CN110571917A (en) * | 2019-09-30 | 2019-12-13 | 华勤通讯技术有限公司 | Switching control circuit and electronic equipment |
-
2018
- 2018-04-17 CN CN201820547014.9U patent/CN208111043U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109586397A (en) * | 2018-12-05 | 2019-04-05 | 新华三技术有限公司 | Power control circuit and electronic equipment |
| CN109586397B (en) * | 2018-12-05 | 2021-01-01 | 新华三技术有限公司 | Power supply control circuit and electronic equipment |
| CN109686322A (en) * | 2019-02-19 | 2019-04-26 | 昆山龙腾光电有限公司 | Switching circuit and backlight drive circuit |
| CN109686322B (en) * | 2019-02-19 | 2021-11-23 | 昆山龙腾光电股份有限公司 | Switching circuit and backlight driving circuit |
| CN110571917A (en) * | 2019-09-30 | 2019-12-13 | 华勤通讯技术有限公司 | Switching control circuit and electronic equipment |
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Address after: 215301, 1, Longteng Road, Kunshan, Jiangsu, Suzhou Patentee after: Kunshan Longteng Au Optronics Co Address before: 215301, 1, Longteng Road, Kunshan, Jiangsu, Suzhou Patentee before: Kunshan Longteng Optronics Co., Ltd. |