CN104754805A - Backlight driving device - Google Patents
Backlight driving device Download PDFInfo
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- CN104754805A CN104754805A CN201310747978.XA CN201310747978A CN104754805A CN 104754805 A CN104754805 A CN 104754805A CN 201310747978 A CN201310747978 A CN 201310747978A CN 104754805 A CN104754805 A CN 104754805A
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- drive device
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Abstract
A backlight driving device is used for driving a backlight unit and comprises a power supply management unit, a backlight driving unit and an overvoltage protection unit; the backlight driving unit is electrically connected with the power supply management unit so as to obtain a power supply which is converted into the driving voltage to be output from a positive output terminal and a negative output terminal, wherein the backlight unit is driven by the driving voltage to emit light; the overvoltage protection unit is electrically connected between the positive output terminal and the negative output terminal. According to the backlight driving device, the overvoltage protection unit is added between the backlight driving unit and the backlight unit and accordingly the feedback protection response speed of the backlight driving device when the load open-circuit fault is produced is improved.
Description
Technical field
The present invention relates to a kind of backlight drive device, particularly relate to a kind of LCD screen backlight drive unit.
Background technology
At present, the LCDs of portable electron device mostly drives luminous based on backlight LED, along with the super largeization of portable electron device LCDs develops, the number of backlight LED strip connection constantly increases, and the required voltage of LED of these series connection reaches four to five times even higher of cell voltage usually.So, the backlight drive device of existing LCDs mostly lacks overvoltage feedback protection circuit, when load end is opened a way, is easy to cause fault.
Summary of the invention
In view of the above circumstances, the invention provides a kind of backlight drive device with overvoltage feedback protection circuit.
A kind of backlight drive device; for driving a back light unit; comprise Power Management Unit, backlight driving unit and Overvoltage protecting unit; this backlight driving unit is electrically connected at described Power Management Unit to obtain power supply; and be drive the driving voltage of back light unit luminescence to be exported by positive-negative output end by this Power convert, this Overvoltage protecting unit is electrically connected between described positive-negative output end.
Described backlight drive device by increasing described Overvoltage protecting unit between this backlight driving unit and this back light unit, and when effectively ensure that load open circuit fault appears in this backlight drive device, its high voltage exported can not cause damage to the circuit of surrounding.This Overvoltage protecting unit principle is simple, improves the feedback protection response speed of backlight drive device when there is load open circuit fault.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the backlight drive device of present pre-ferred embodiments.
Main element symbol description
Following embodiment will further illustrate the present invention in conjunction with above-mentioned accompanying drawing.
Embodiment
Refer to Fig. 1, the backlight drive device 100 that present pre-ferred embodiments provides is applicable to the back light unit 50 of the LCDs driving portable electron device, comprises Power Management Unit 10, filter unit 20, energy-storage units 30, backlight driving unit 40.Described backlight driving unit 40 comprises backlight driving chip U1 and Overvoltage protecting unit 41, and described backlight driving unit 40 is connected with described Power Management Unit 10, filter unit 20, energy-storage units 30 and back light unit 50, for driving this back light unit 50 luminous.
Described Power Management Unit 10 provides electric energy for this backlight drive device 100.Described Power Management Unit 10 comprises a universal input/output (General Purpose Input/Output, GPIO) pin and a power supply output pin V1, this GPIO pin is for exporting a high level or low level control signal, to control unlatching or the closedown of described backlight driving chip U1, this power supply output pin V1 is used for out-put supply to backlight driving chip U1.
Described backlight driving chip U1 comprises power input VIN, enable control end CTRL, change over switch end SW, feedback end FB, error compensation end COMP and earth terminal GND.Wherein, this power input VIN is connected with the power supply output pin V1 of described Power Management Unit 10, for obtaining electric energy from described Power Management Unit 10; This enable control end CTRL is connected with the GPIO pin of Power Management Unit 10 by the first resistance R1, for the control signal exported according to this GPIO pin, as level high or low of control signal, control unlatching or the closedown of this backlight driving chip U1, this enable control end CTRL is also by one second resistance R2 ground connection; This change over switch end SW is connected to power input VIN by described energy-storage units 30, and store or release electric energy to control described energy-storage units for output signal, this change over switch end SW is also connected with the positive pole of a rectifier diode D1; This feedback end FB is connected to described Overvoltage protecting unit 41; This error compensation end COMP is by a building-out capacitor C4 ground connection; This earth terminal GND ground connection.
Described filter unit 20 comprises the first electric capacity C1, the second electric capacity C2 and the 3rd electric capacity C3.Between the power supply output pin V1 that this first electric capacity C1 and the 3rd electric capacity C3 one end are all electrically connected on described Power Management Unit 10 and described backlight driving chip U1, the equal ground connection of the other end, for the high frequency ripple of filter out power administrative unit 10 output voltage.This second electric capacity C2 one end is connected between the enable control end CTRL of described first resistance R1 and described backlight driving chip U1, other end ground connection, carries out filtering, to ensure the accuracy of control signal for the control signal exported described Power Management Unit 10.
Described energy-storage units 30 comprises energy storage inductor L1, and this energy storage inductor L1 is electrically connected between the power input VIN of described backlight driving chip U1 and change over switch end SW, under the control of this backlight driving chip U1, stores or release electric energy.When the control signal from this GPIO pin that the enable control end CTRL of this backlight driving chip U1 receives is high level, this backlight driving chip U1 is outputed signal by its change over switch end SW and controls this energy-storage units 30 storage of electrical energy; When the control signal from this GPIO pin of the reception of enable control end CTRL is low level, this backlight driving chip U1 outputs signal this energy-storage units 30 of control by its change over switch end SW and discharges electric energy, to be driven described back light unit 50 luminous by described backlight driving unit 40.
Described backlight driving unit 40 also comprises rectifier diode D1, filter inductance L2, earth resistance R3 and filter capacitor C5.Described rectifier diode D1, filter inductance L2, Overvoltage protecting unit 41 and this earth resistance R3 are series between described change over switch end SW and ground successively.The positive pole of this rectifier diode D1 is electrically connected with the change over switch end SW of this backlight driving chip U1, and negative pole is electrically connected with one end of this filter inductance L2, carries out rectification, to obtain direct current signal for the AC signal exported described energy-storage units 30.The other end of this filter inductance L2 is the positive output end VOUT+ of this backlight driving unit 40.This filter capacitor C5 one end is connected between the negative pole of this rectifier diode D1 and this filter inductance L2, other end ground connection.This filter capacitor C5 and this filter inductance L2 forms LC filter circuit, is superimposed upon the high frequency ripple on the direct current signal of rectifier diode D1 output for filtering.Described Overvoltage protecting unit 41 comprises the voltage stabilizing didoe D2 and divider resistance R4 that are connected in series.The feedback end FB of this backlight driving chip U1 is connected between this voltage stabilizing didoe D2 and divider resistance R4.In the present embodiment, this voltage stabilizing didoe D2 is Zener diode, and its positive pole is connected with this divider resistance R4, and its negative pole is connected to described change over switch end SW by this filter inductance L2 and rectifier diode D1.Node between this earth resistance R3 and Overvoltage protecting unit 41 is the negative output terminal VOUT-of this backlight driving unit 40.This Overvoltage protecting unit 41 is electrically connected between positive-negative output end VOUT+ and VOUT-of this backlight driving unit 40.
Described back light unit 50 is connected between positive-negative output end VOUT+ and VOUT-of backlight driving unit 40, therefore forms parallel connectivity with described Overvoltage protecting unit 41.This back light unit 50 comprises the light-emitting diode 51 of multiple series connection, for luminous under the driving of described backlight driving unit 40.In the present embodiment, this back light unit 50 comprises at least 6 light-emitting diodes 51 of mutually connecting.
Further illustrate the operation principle of this Overvoltage protecting unit 41 below.Under Utopian transfer function, when the duty ratio D of described backlight driving chip U1 is close to its maximum, this backlight driving unit 40 can be made to produce high output voltage.In the present embodiment, the maximum of getting this duty ratio D is 90%, and the power input VIN voltage of this backlight driving chip U1 is 4V, then the output voltage of this backlight driving unit 40 is: 4/ (1-0.9)=40V.The output voltage that this backlight driving unit 40 is so high probably exceeds the maximum withstand voltage of peripheral assembly, if the overvoltage protection monitoring mechanism of this backlight driving chip U1 fails to respond in time, then may cause fault.Present pre-ferred embodiments is connected in parallel on the output of this backlight driving unit 40 after utilizing voltage stabilizing didoe D2 and divider resistance R4 to connect; form Overvoltage protecting unit 41; even if the overvoltage protection monitoring mechanism of this backlight driving chip U1 fails to respond in time; this Overvoltage protecting unit 41 also can available protecting circuit not damaged, and the power consumption of this Overvoltage protecting unit 41 is negligible.
Particularly, when there is open fault in described back light unit 50, the feedback end FB of described backlight driving chip U1 is pulled down to ground, in order to the voltage maintaining this feedback end FB is in normal value, this backlight driving chip U1 is under the effect of feedback monitoring mechanism, its duty ratio can be increased as much as possible, thus cause the output voltage of described backlight driving unit 40 to rise, until described voltage stabilizing didoe D2 opens, now electric current flows through this voltage stabilizing didoe D2, ground is got back to after divider resistance R4 and earth resistance R3, thus effectively prevent the infringement of too high output voltage to other components and parts in circuit.In the present embodiment, the selection of this voltage stabilizing didoe D2 should ensure when this backlight driving unit 40 normally works, electric current is not had to flow through this voltage stabilizing didoe D2, therefore, the reverse breakdown voltage of selected voltage stabilizing didoe D2 at least should be greater than maximum load voltage (i.e. the operating voltage of this back light unit 50) about the 2V of this backlight driving unit 40, must be less than the maximum rated output voltage of this backlight driving unit 40 simultaneously.This divider resistance R4 should choose the as far as possible large resistance of resistance, to minimize the power consumption of this voltage stabilizing didoe D2.
Described backlight drive device 100; by the Overvoltage protecting unit 41 be composed in series by voltage stabilizing didoe D2 and divider resistance R4 in the output parallel connection one of described backlight driving unit 40; make this backlight drive device 100 when open fault appears in back light unit 50; quick response is directly made by this Overvoltage protecting unit 41; by the voltage ground that this backlight driving unit 40 exports, protective circuit is not damaged by too high output voltage.This Overvoltage protecting unit 41 circuit structure is simple, and has low-power consumption, high efficiency feature.
The above, be only preferred embodiment of the present invention, is not to do any pro forma restriction to the present invention.In addition, those skilled in the art also can do other change in spirit of the present invention, and certainly, these changes done according to the present invention's spirit, all should be included within the present invention's scope required for protection.
Claims (10)
1. a backlight drive device; for driving a back light unit; comprise Power Management Unit and backlight driving unit; it is characterized in that: described backlight drive device also comprises Overvoltage protecting unit; this backlight driving unit is electrically connected at described Power Management Unit to obtain power supply; and be drive the driving voltage of back light unit luminescence to be exported by positive-negative output end by this Power convert, this Overvoltage protecting unit is electrically connected between described positive-negative output end.
2. backlight drive device as claimed in claim 1, it is characterized in that: described backlight drive device also comprises energy-storage units, described backlight driving chip comprises power input, enable control end and change over switch end, this power input is used for obtaining electric energy from described Power Management Unit, this enable control end is for receiving the control signal controlling this backlight driving chip and open or close, and this change over switch end controls the storage of this energy-storage units or release electric energy for outputing signal.
3. backlight drive device as claimed in claim 2; it is characterized in that: described backlight driving unit also comprises rectifier diode, filter inductance and earth resistance; this rectifier diode, filter inductance, Overvoltage protecting unit and this earth resistance are series between the change over switch end of described backlight driving chip and ground successively; the positive pole of this rectifier diode is connected with change over switch end; node between filter inductance and Overvoltage protecting unit is described positive output end, and the node between earth resistance and Overvoltage protecting unit is described negative output terminal ground.
4. backlight drive device as claimed in claim 3; it is characterized in that: described Overvoltage protecting unit comprises voltage stabilizing didoe and the divider resistance of series connection; this voltage stabilizing didoe positive pole is connected with this divider resistance, and its negative pole is connected to the change over switch end of described backlight driving chip by this filter inductance and rectifier diode.
5. backlight drive device as claimed in claim 4, is characterized in that: described voltage stabilizing didoe is Zener diode.
6. backlight drive device as claimed in claim 2, it is characterized in that: this backlight drive device also comprises the first resistance and the second resistance, the enable control end of described backlight driving chip is connected to the universal input output pin of described Power Management Unit to input described control signal, between this second resistance this enable control end and ground by this first resistance.
7. backlight drive device as claimed in claim 3, it is characterized in that: described backlight drive device also comprises multiple filter capacitor, the power input of backlight driving chip, enable control end and the node between rectifier diode and filter inductance are respectively by a filter capacitor ground connection.
8. backlight drive device as claimed in claim 2, it is characterized in that: described energy-storage units comprises energy storage inductor, this energy storage inductor is connected between the power input of described backlight driving chip and change over switch end.
9. backlight drive device as claimed in claim 1, is characterized in that: described back light unit comprises at least 6 light-emitting diodes of mutually connecting.
10. backlight drive device as claimed in claim 4, is characterized in that: the reverse breakdown voltage of described voltage stabilizing didoe is greater than maximum load voltage about the 2V of this backlight driving unit, is less than the maximum rated output voltage of this backlight driving unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310747978.XA CN104754805A (en) | 2013-12-31 | 2013-12-31 | Backlight driving device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310747978.XA CN104754805A (en) | 2013-12-31 | 2013-12-31 | Backlight driving device |
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| Publication Number | Publication Date |
|---|---|
| CN104754805A true CN104754805A (en) | 2015-07-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310747978.XA Pending CN104754805A (en) | 2013-12-31 | 2013-12-31 | Backlight driving device |
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| CN (1) | CN104754805A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105405422A (en) * | 2015-12-10 | 2016-03-16 | 昆山龙腾光电有限公司 | Voltage stabilizing power supply circuit and liquid crystal display device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201267026Y (en) * | 2008-10-06 | 2009-07-01 | 李春海 | Drive circuit of mixing light source |
| CN102970791A (en) * | 2012-11-01 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Light-emitting diode (LED) constant current driving circuit and LED lamp |
-
2013
- 2013-12-31 CN CN201310747978.XA patent/CN104754805A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201267026Y (en) * | 2008-10-06 | 2009-07-01 | 李春海 | Drive circuit of mixing light source |
| CN102970791A (en) * | 2012-11-01 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Light-emitting diode (LED) constant current driving circuit and LED lamp |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105405422A (en) * | 2015-12-10 | 2016-03-16 | 昆山龙腾光电有限公司 | Voltage stabilizing power supply circuit and liquid crystal display device |
| CN105405422B (en) * | 2015-12-10 | 2018-07-06 | 昆山龙腾光电有限公司 | A kind of voltage-stabilized power supply circuit and liquid crystal display device |
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Application publication date: 20150701 |
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