CN206210358U - A kind of overvoltage crowbar and LED backlight drive circuit - Google Patents
A kind of overvoltage crowbar and LED backlight drive circuit Download PDFInfo
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- CN206210358U CN206210358U CN201621212137.4U CN201621212137U CN206210358U CN 206210358 U CN206210358 U CN 206210358U CN 201621212137 U CN201621212137 U CN 201621212137U CN 206210358 U CN206210358 U CN 206210358U
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- resistance
- switch pipe
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- overvoltage crowbar
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Abstract
The utility model discloses a kind of overvoltage crowbar, including boost module, LED drive chip, sampling module and switch module；The boosting rectifier control input of the boost module is connected with the boosting rectifier control output end of LED drive chip; the sampling end of the sampling module is connected with the power output end of boost module; the over-pressed signal output part of the sampling module is connected with the over-pressed signal input part of switch module, and the triggering end of the switch module is connected with the overvoltage protection end of LED drive chip.Accordingly, the invention also discloses a kind of LED backlight drive circuit.Sampling module of the present utility model is sampled to the voltage that boost module is exported; over-pressed signal is sent to switch module in overvoltage; switch module receives direct electric conduction source and triggering end after over-pressed signal; triggering LED drive chip enters overvoltage protection; so as to accurately trigger overvoltage protection; the precision of overvoltage protection is improved, the stability of backlight drive is improve.
Description
Technical field
The utility model is related to electronic technology field, more particularly to a kind of overvoltage crowbar and LED backlight drive circuit.
Background technology
Liquid crystal display device is widely used because having many merits such as thin fuselage, power saving, radiationless.It is existing
It is backlight liquid crystal display device that the liquid crystal display device of in the market is most of.In backlight liquid crystal display device, liquid crystal panel
Itself do not light, LED backlight is oppositely arranged to come just to liquid crystal display panel for providing display light source with liquid crystal display panel
Image is often shown, wherein, LED backlight includes at least one LED string.Drive in the drive circuit of the LED backlight and lead to
Frequently with special LED drive chip, in order to avoid being damaged when LED is in open-circuit condition or other failures cause overtension
Bad interlock circuit component, current LED drive chip is typically provided an OVP pin (output over-voltage protection).
Fig. 1 show the LED backlight drive circuit of prior art offer, including boost module 1, LED drive chip 2, the
One resistance R1, second resistance R2 and LED string 5.Boost module 1 is the offer driving of LED string 5 after being boosted to input power
Power supply, first resistor R1 and second resistance R2 carry out partial pressure sampling to the driving power supply, when sampled voltage drives core more than LED
During the OVP voltage thresholds of piece 2, the control boost module 1 of LED drive chip 2 is stopped, and voltage no longer rises, to protect backlight
Component in drive circuit.But the OVP protections voltage threshold error of many LED drive chips is larger, up to ± 5%~
20%, lead to not the over-pressed signal of correct identification, the false triggering LED drive chip overvoltage protection in LED normal works, or mistake
Non- triggered as normal overvoltage protection during pressure, damages circuit components.
The content of the invention
Technical problem to be solved in the utility model is, there is provided a kind of overvoltage crowbar and LED-backlit drive electricity
Road, can accurately trigger the overvoltage protection of LED drive chip, the precision of overvoltage protection be improved, so as to improve the steady of backlight drive
It is qualitative.
In order to solve the above-mentioned technical problem, the utility model provide a kind of overvoltage crowbar, including boost module,
LED drive chip, sampling module and switch module；
The boost module includes boosting rectifier control input, power input and is exported for connecting the power supply of LED string
End；The LED drive chip includes boosting rectifier control output end and overvoltage protection end；The sampling module includes sampling end and overvoltage
Signal output part；The switch module includes over-pressed signal input part, triggering end and the power supply for being connected with direct voltage source
End；
The boosting rectifier control input is connected with the boosting rectifier control output end, the sampling end and the power output end
Connection, the over-pressed signal output part is connected with the over-pressed signal input part, and the triggering end connects with the overvoltage protection end
Connect.
Further, the sampling module also includes first resistor, second resistance, 3rd resistor and three end adjustable reference sources
Chip；
The first end of the first resistor is connected with the sampling end, and the second end of the first resistor connects described respectively
The reference pole of the first end of second resistance and the three ends adjustable reference source chip, the second end ground connection of the second resistance, institute
The plus earth of three end adjustable reference source chips is stated, the negative electrode of the three ends adjustable reference source chip connects the 3rd electricity respectively
Second end of resistance and the over-pressed signal output part, the first end of the 3rd resistor are used to connect direct voltage source.
Further, the three ends adjustable reference source chip is chip TL431.
Further, the switch module also includes the 4th resistance, the 5th resistance and first switch pipe；
The first end of the first switch pipe connects the power end by the 4th resistance, the first switch pipe
Control end connects the over-pressed signal input part, and the second end of the first switch pipe connects the first of the 5th resistance respectively
End and the triggering end, the second end of the 5th resistance are grounded.
Preferably, the first switch pipe is PNP type triode, the transmitting extremely described first of the PNP type triode
The first end of switching tube, the second end of the extremely described first switch pipe of current collection of the PNP type triode, the pole of the positive-negative-positive three
The base stage of pipe is the control end of the first switch pipe.
Further, the boost module also includes that the 6th resistance, the 7th resistance, inductance, diode, electric capacity and second are opened
Guan Guan；
The first end of the inductance is connected with the power input, and the second end of the inductance connects two pole respectively
The first end of the positive pole of pipe and the second switch pipe, the negative pole of the diode is connected with the first end of the electric capacity, described
The first end of electric capacity is connected with the power output end, the second end ground connection of the electric capacity, the control end of the second switch pipe
The boosting rectifier control input is connected by the 6th resistance, the second end of the second switch pipe passes through the 7th resistance
Ground connection.
Preferably, the second switch pipe is N-channel MOS pipe, and the drain electrode of the N-channel MOS pipe is the second switch
The first end of pipe, the source electrode of the N-channel MOS pipe is the second end of the second switch pipe, the grid of the N-channel MOS pipe
It is the control end of the second switch pipe.
The overvoltage crowbar that the utility model is provided, sampling module is sampled to the voltage that boost module is exported, when
When there is overvoltage, sampling module sends over-pressed signal to switch module, and switch module receives direct turn-on power after over-pressed signal
End and triggering end, triggering LED drive chip enter overvoltage protection, and LED drive chip control boost module stops to input power
Boosting work, with the component in protection circuit.By original sampled voltage, directly triggering is changed to be triggered by direct voltage source,
So as to accurate triggering overvoltage protection, the precision of overvoltage protection is improve, improve the stability of backlight drive.
Correspondingly, the utility model additionally provides a kind of LED backlight drive circuit, including overvoltage crowbar, LED string
With the 8th resistance；
The overvoltage crowbar is foregoing overvoltage crowbar；
The LED string includes electrode input end, output end and the M LED of series connection；
The power output end of the boost module in the overvoltage crowbar connects with the electrode input end of the LED string
Connect, the output end of the LED string passes through the 8th resistance eutral grounding.
Further, M >=2.
The LED backlight drive circuit that the utility model is provided, boost module input power is boosted after for LED string
Driving power supply is provided, sampling module is sampled to the voltage of the driving power supply, when over-pressed, sampling module sends over-pressed signal
To switch module, switch module receives direct electric conduction source and triggering end after over-pressed signal, and triggering LED drive chip entered
Pressure protection, LED drive chip controls the boost module to stop the boosting work to input power, with the first device in protection circuit
Part.By original sampled voltage, directly triggering is changed to be triggered by direct voltage source, so as to accurate triggering overvoltage protection, improves
The precision of overvoltage protection, improves the stability of backlight drive.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of the LED backlight drive circuit that prior art is provided；
Fig. 2 is a kind of circuit block diagram of overvoltage crowbar that the utility model is provided；
Fig. 3 is a kind of circuit theory diagrams of the one embodiment for overvoltage crowbar that the utility model is provided；
Fig. 4 is a kind of second circuit theory diagrams of embodiment of overvoltage crowbar that the utility model is provided；
Fig. 5 is a kind of the 3rd circuit theory diagrams of embodiment of overvoltage crowbar that the utility model is provided；
Fig. 6 is a kind of circuit theory diagrams of the one embodiment for LED backlight drive circuit that the utility model is provided.
Specific embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of the utility model, rather than whole
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment for being obtained, belongs to the scope of the utility model protection.
It is a kind of circuit block diagram of overvoltage crowbar that the utility model is provided referring to Fig. 2.
The utility model embodiment provides a kind of overvoltage crowbar, including boost module 21, LED drive chip 22, adopts
Egf block 23 and switch module 24；
The boost module 1 includes boosting rectifier control input Ctr, power input Vin and the electricity for connecting LED string
Source output terminal Vout；
The LED drive chip 22 includes boosting rectifier control output end GATE and overvoltage protection end OVP；
The sampling module 23 includes sampling end DI and over-pressed signal output part DO；
The switch module 24 includes over-pressed signal input part SW, triggering end TR and the electricity for being connected with direct voltage source
Source IN；
The boosting rectifier control input Ctr is connected with boosting rectifier control output end GATE, and the sampling end DI is exported with power supply
End Vout connections, the over-pressed signal output part DO is connected with overvoltage signal input part SW, the triggering end TR and overvoltage protection
End connection OVP.
In the specific implementation, sampling module 23 is exported by sampling end DI to the power output end Vout of boost module 21
Voltage is sampled, and when over-pressed, sampling module 23 passes through over-pressed signal output part DO and sends over-pressed signal to switch module 24, opens
The direct electric conduction source IN and triggering end TR after overvoltage signal input part SW receives over-pressed signal of module 24 is closed, LED is triggered
Driving chip 22 enters overvoltage protection, and LED drive chip 22 is sent a control signal to described by boosting rectifier control output end GATE
The boosting rectifier control input Ctr of boost module 21, control boost module 21 stops the boosting work to input power, to protect electricity
Component in road.By original sampled voltage, directly triggering is changed to be triggered by direct voltage source, so as to accurate triggering overvoltage
Protection, improves the precision of overvoltage protection, improves the stability of backlight drive.
It is a kind of circuit theory diagrams of the one embodiment for overvoltage crowbar that the utility model is provided referring to Fig. 3.
As shown in figure 3, the sampling module 23 also includes first resistor RA1, second resistance RA2,3rd resistor RA3 and three end adjustable substrates
Quasi- source chip U1；
The first end of the first resistor RA1 is connected with sampling end DI, and second end of the first resistor RA1 connects respectively
The reference pole of the first end of second resistance RA2 and three end adjustable reference source chip U1, second termination of the second resistance RA2
Ground, the plus earth of the three ends adjustable reference source chip U1, the negative electrode of the three ends adjustable reference source chip U1 is connected respectively
The first end of second end of 3rd resistor RA3 and over-pressed signal output part DO, the 3rd resistor RA3 is used to connect DC voltage
Source.
The course of work of wherein sampling module 23 is as follows：Electricity of the first resistor RA1 and second resistance RA2 to boost module 21
The voltage of source output terminal Vout outputs carries out partial pressure sampling, when inside ginseng of the sampled voltage more than three end adjustable reference source chip U1
When examining voltage, three end adjustable reference source chip U1 conductings, sampling module 23 is sent out over-pressed signal by overvoltage signal output part DO
Deliver to the over-pressed signal input part SW of switch module 24.Three end adjustable reference source chip U1 are because of its high precision, good stability and receive
Temperature influences small characteristic, can accurately identify over-pressed signal, so as to further improve the precision of overvoltage protection.
Wherein, the three ends adjustable reference source chip U1 is chip TL431, the internal reference voltage precision of chip TL431
Up to 0.4%.
It is a kind of second circuit theory diagrams of embodiment of overvoltage crowbar that the utility model is provided referring to Fig. 4.
As shown in figure 4, the switch module 24 also includes the 4th resistance RA4, the 5th resistance RA5 and first switch pipe Q1；
The first end of the first switch pipe Q1 connects power end IN, the first switch pipe Q1 by the 4th resistance RA4
Second end of control end connection over-pressed signal input part SW, the first switch pipe Q1 connect the of the 5th resistance RA5 respectively
The second end ground connection of one end and triggering end TR, the 5th resistance RA5.
Wherein, the course of work of switch module 24 is as follows：When the control end of first switch pipe Q1 is input into by control signal
After end SW receives over-pressed signal, first switch pipe Q1 conductings, the 4th resistance RA4 and the 5th resistance RA5 are to the straight of power end IN
Stream voltage carries out partial pressure, so that for LED drive chip 22 provides overvoltage protection trigger voltage；When the control end of first switch pipe Q1
When being not received by over-pressed signal, first switch pipe Q1 cut-offs.
Preferably, the first switch pipe Q1 is PNP type triode, and the transmitting extremely first of the PNP type triode is opened
Close the first end of pipe Q1, current collection extremely second end of first switch pipe Q1, the PNP type triode of the PNP type triode
Base stage for first switch pipe Q1 control end.
It is a kind of the 3rd circuit theory diagrams of embodiment of overvoltage crowbar that the utility model is provided referring to Fig. 4.
As shown in figure 4, the boost module 21 also includes the 6th resistance RA6, the 7th resistance RA7, inductance L, diode D, electric capacity C and the
Two switching tube Q2；
The first end of the inductance L is connected with power input Vin, and second end of the inductance L connects diode D respectively
Positive pole and second switch pipe Q2 first end, the negative pole of the diode D is connected with the first end of electric capacity C, the electric capacity C's
First end is connected with power output end Vout, and the second end ground connection of the electric capacity C, the control end of the second switch pipe Q2 passes through
Second end of the 6th resistance RA6 connection boosting rectifier controls input Ctr, the second switch pipe Q2 is grounded by the 7th resistance RA7.
Wherein, the course of work of boost module 24 is as follows：When circuit normal work, the control end of second switch pipe Q2 is led to
Cross the 6th resistance RA6 and receive the square-wave signal that LED drive chip 22 sends.During high level, second switch pipe Q2 conductings, inductance L
Charge, diode D is used to prevent electric capacity C from discharging over the ground；During low level, second switch pipe Q2 cut-offs, inductance L is allowed to discharge through two
Pole pipe D charges for electric capacity C, and LED drive chip 22 is continuously second switch pipe Q2 and provides square-wave signal, second switch pipe Q2 break-makes
Process constantly repeat, obtain the voltage higher than input voltage at electric capacity C two ends；During circuit overvoltage, LED drive chip 22 is no longer
Square-wave signal is sent, boost module 21 is stopped.
Preferably, the second switch pipe is N-channel MOS pipe, and the drain electrode of the N-channel MOS pipe is second switch pipe Q2
First end, the source electrode of the N-channel MOS pipe is second end of second switch pipe Q2, and the grid of the N-channel MOS pipe is the
The control end of two switching tube Q2.
It is a kind of circuit theory of the one embodiment for LED backlight drive circuit that the utility model is provided referring to Fig. 6
Figure.
The utility model provides a kind of LED backlight drive circuit, including overvoltage crowbar 26, LED string 25 and the 8th
Resistance RA8；
Described in a kind of any embodiment of overvoltage crowbar that the overvoltage crowbar 26 is provided for the utility model
Overvoltage crowbar；
The LED string 25 includes the LED LED1- of electrode input end LED_IN, output end LED_OUT and M series connection
LEDM；
The positive pole of the power output end Vout of the boost module 21 in the overvoltage crowbar 26 and the LED string 25
Input LED_IN is connected, and the output end LED_OUT of the LED string 25 is grounded by the 8th resistance RA8.
Further, M >=2.
In the specific implementation, for LED string 25 provides driving power supply after boost module 21 boosts to input power, adopt
Egf block 23 is sampled by sampling end DI to the voltage of the driving power supply, and when over-pressed, sampling module 23 is believed by overvoltage
Number output end DO sends over-pressed signal to switch module 24, and switch module 24 receives over-pressed signal by overvoltage signal input part SW
Direct electric conduction source IN and triggering end TR, triggers LED drive chip 22 and enters overvoltage protection afterwards, and LED drive chip 22 passes through
Boosting rectifier control output end GATE sends a control signal to the boosting rectifier control input Ctr of boost module 21, controls boost module 21
Stop the boosting work to input power, with the component in protection circuit.By original sampled voltage directly triggering be changed to by
Direct voltage source is triggered, and so as to accurate triggering overvoltage protection, improves the precision of overvoltage protection, improves the steady of backlight drive
It is qualitative.
It should be noted that in the overvoltage crowbar and LED backlight drive circuit of above-described embodiment offer, first switch
Pipe Q1 is PNP type triode and second switch pipe Q2 is N-channel MOS pipe, a kind of implementation method only therein, in other realities
Apply in mode, first switch pipe Q1 may be replaced by N-channel MOS pipe or other three ports for control switching devices or it derives from device
Part, second switch pipe Q2 may be replaced by PNP type triode or other three ports for control switching devices or it derives from device, not
With application scenario in, the power consumption, cost, driving power depending on side circuit and the drive control component parameters with switching tube
With etc. require reasonable selection and setting, from and set switching tube be prior art conventional design process, do not gone to live in the household of one's in-laws on getting married herein
State.
Overvoltage crowbar and LED backlight drive circuit that the utility model is provided, sampling module are exported to boost module
Voltage sampled, when there is overvoltage, sampling module sends over-pressed signal to switch module, and switch module receives over-pressed letter
Direct electric conduction source and triggering end after number, triggering LED drive chip enter overvoltage protection, and LED drive chip control rises pressing mold
Block stops the boosting work to input power, with the component in protection circuit.By original sampled voltage, directly triggering is changed to
Triggered by direct voltage source, so as to accurate triggering overvoltage protection, improve the precision of overvoltage protection, improve backlight drive
Stability.
The above is preferred embodiment of the present utility model, it is noted that for the ordinary skill of the art
For personnel, on the premise of the utility model principle is not departed from, some improvements and modifications can also be made, these improve and moisten
Decorations are also considered as protection domain of the present utility model.
Claims (9)
1. a kind of overvoltage crowbar, it is characterised in that including boost module, LED drive chip, sampling module and switching molding
Block；
The boost module includes boosting rectifier control input, power input and the power output end for connecting LED string；Institute
Stating LED drive chip includes boosting rectifier control output end and overvoltage protection end；The sampling module includes sampling end and over-pressed signal
Output end；The switch module includes over-pressed signal input part, triggering end and the power end for being connected with direct voltage source；
The boosting rectifier control input is connected with the boosting rectifier control output end, and the sampling end connects with the power output end
Connect, the over-pressed signal output part is connected with the over-pressed signal input part, the triggering end is connected with the overvoltage protection end.
2. overvoltage crowbar as claimed in claim 1, it is characterised in that the sampling module also includes first resistor, the
Two resistance, 3rd resistor and three end adjustable reference source chips；
The first end of the first resistor is connected with the sampling end, and the second end of the first resistor connects described second respectively
The reference pole of the first end of resistance and the three ends adjustable reference source chip, the second end ground connection of the second resistance, described three
The plus earth of adjustable reference source chip is held, the negative electrode of the three ends adjustable reference source chip connects the 3rd resistor respectively
Second end and the over-pressed signal output part, the first end of the 3rd resistor are used to connect direct voltage source.
3. overvoltage crowbar as claimed in claim 2, it is characterised in that the three ends adjustable reference source chip is chip
TL431。
4. overvoltage crowbar as claimed in claim 1, it is characterised in that the switch module also includes the 4th resistance, the
Five resistance and first switch pipe；
The first end of the first switch pipe connects the power end, the control of the first switch pipe by the 4th resistance
The end connection over-pressed signal input part, the second end of the first switch pipe connect respectively the 5th resistance first end and
The triggering end, the second end ground connection of the 5th resistance.
5. overvoltage crowbar as claimed in claim 4, it is characterised in that the first switch pipe is PNP type triode, institute
State the first end of the extremely described first switch pipe of transmitting of PNP type triode, the current collection of the PNP type triode extremely described the
Second end of one switching tube, the base stage of the PNP type triode is the control end of the first switch pipe.
6. overvoltage crowbar as claimed in claim 1, it is characterised in that the boost module also includes the 6th resistance, the
Seven resistance, inductance, diode, electric capacity and second switch pipe；
The first end of the inductance is connected with the power input, and the second end of the inductance connects the diode respectively
The first end of positive pole and the second switch pipe, the negative pole of the diode is connected with the first end of the electric capacity, the electric capacity
First end be connected with the power output end, the second end of electric capacity ground connection, the control end of the second switch pipe passes through
6th resistance connects the boosting rectifier control input, and the second end of the second switch pipe is connect by the 7th resistance
Ground.
7. overvoltage crowbar as claimed in claim 6, it is characterised in that the second switch pipe is N-channel MOS pipe, institute
The drain electrode for stating N-channel MOS pipe is the first end of the second switch pipe, and the source electrode of the N-channel MOS pipe is the second switch
Second end of pipe, the grid of the N-channel MOS pipe is the control end of the second switch pipe.
8. a kind of LED backlight drive circuit, it is characterised in that including overvoltage crowbar, LED string and the 8th resistance；
The overvoltage crowbar is the overvoltage crowbar as described in any one of claim 1 to 7；
The LED string includes electrode input end, output end and the M LED of series connection；
The power output end of the boost module in the overvoltage crowbar is connected with the electrode input end of the LED string, institute
The output end for stating LED string passes through the 8th resistance eutral grounding.
9. LED backlight drive circuit as claimed in claim 8, it is characterised in that M >=2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621212137.4U CN206210358U (en) | 2016-11-10 | 2016-11-10 | A kind of overvoltage crowbar and LED backlight drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621212137.4U CN206210358U (en) | 2016-11-10 | 2016-11-10 | A kind of overvoltage crowbar and LED backlight drive circuit |
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| Publication Number | Publication Date |
|---|---|
| CN206210358U true CN206210358U (en) | 2017-05-31 |
Family
ID=58752204
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201621212137.4U Active CN206210358U (en) | 2016-11-10 | 2016-11-10 | A kind of overvoltage crowbar and LED backlight drive circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107197569A (en) * | 2017-07-25 | 2017-09-22 | 合肥惠科金扬科技有限公司 | A kind of LED backlight Drive Protecting Circuit and display device |
| CN108665859A (en) * | 2018-08-01 | 2018-10-16 | 合肥惠科金扬科技有限公司 | Backlight control circuit and backlight |
| CN109958887A (en) * | 2017-12-25 | 2019-07-02 | 上海复弘科技发展有限公司 | Operation shadowless lamp color temperature adjusting system |
| CN110337159A (en) * | 2019-07-02 | 2019-10-15 | 厦门厦华科技有限公司 | A kind of large scale electronic whiteboard backlight drive circuit that control signal can be reset |
-
2016
- 2016-11-10 CN CN201621212137.4U patent/CN206210358U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107197569A (en) * | 2017-07-25 | 2017-09-22 | 合肥惠科金扬科技有限公司 | A kind of LED backlight Drive Protecting Circuit and display device |
| CN109958887A (en) * | 2017-12-25 | 2019-07-02 | 上海复弘科技发展有限公司 | Operation shadowless lamp color temperature adjusting system |
| CN108665859A (en) * | 2018-08-01 | 2018-10-16 | 合肥惠科金扬科技有限公司 | Backlight control circuit and backlight |
| CN108665859B (en) * | 2018-08-01 | 2023-12-29 | 合肥惠科金扬科技有限公司 | Backlight source control circuit and backlight source |
| CN110337159A (en) * | 2019-07-02 | 2019-10-15 | 厦门厦华科技有限公司 | A kind of large scale electronic whiteboard backlight drive circuit that control signal can be reset |
| CN110337159B (en) * | 2019-07-02 | 2024-03-05 | 厦门厦华科技有限公司 | Large-size electronic whiteboard backlight drive circuit with resettable control signals |
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