CN104952398B - A kind of LED backlight drive circuit and LCD display - Google Patents
A kind of LED backlight drive circuit and LCD display Download PDFInfo
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- CN104952398B CN104952398B CN201410114905.1A CN201410114905A CN104952398B CN 104952398 B CN104952398 B CN 104952398B CN 201410114905 A CN201410114905 A CN 201410114905A CN 104952398 B CN104952398 B CN 104952398B
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Abstract
The embodiment of the invention discloses a kind of LED backlight drive circuit and LCD displays; wherein; the circuit includes: that DC/DC boost chip U1, power supply circuit, square-wave signal conversion circuit, protection circuit, voltage detecting circuit, backlight LED load circuit, metal-oxide-semiconductor Q2, inductance L1, diode D2, the DC/DC boost chip U1, the metal-oxide-semiconductor Q2, the inductance L1 and the diode D2 constitute booster circuit；The power supply circuit is powered to the DC/DC boost chip U1, and the DC/DC boost chip U1 provides voltage by the metal-oxide-semiconductor Q2 for the backlight LED load circuit；The backlight LED load circuit, which is separately connected the voltage detecting circuit, the square-wave signal conversion circuit and the protection circuit, makes backlight LED voltage stabilization, and the present invention can save electric energy and extend the service life of LCD display.
Description
Technical field
The present invention relates to field of circuit technology more particularly to a kind of LED backlight drive circuit and LCD displays.
Background technique
Currently, cold-cathode fluorescence lamp CCFL is widely used in LCD display as backlight, CCFL backlight drive circuit is made
For the important component of backlight control circuit, complex circuit keeps the service life of cold-cathode fluorescence lamp CCFL short, and power consumption
Amount is very much not able to satisfy energy-efficient needs.
Summary of the invention
The technical problem to be solved by the embodiment of the invention is that providing a kind of LED backlight drive circuit and LCD is shown
LED can be used as backlight in device, and route simply can reach energy saving purpose.
In order to solve the above-mentioned technical problem, the embodiment of the invention provides a kind of LED backlight drive circuits, including DC/DC
Boost chip U1, input terminal CON1, power supply circuit, square-wave signal conversion circuit, protection circuit, voltage detecting circuit, backlight
Source LED load circuit, resistance R6, metal-oxide-semiconductor Q2, inductance L1, diode D2, fuse F1, capacitor C3, resistance R3, diode D1,
Resistance R4;
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the back
The connection of light source led load circuit, also passes through the fuse F1, the electricity of the power supply circuit and the DC/DC boost chip U1
Source pin VDD connection；The input terminal CON1 also makes can control by the resistance R3 and DC/DC boost chip U1
Pin EA connection；The input terminal CON1 also passes through the diode D1, the resistance R4 and the DC/DC boost chip U1
The INN connection of pwm signal input pin；The protection circuit also passes through the capacitor C3's and DC/DC boost chip U1
Compensation pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, described
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, two pole
Pipe D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through described
Voltage detecting circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and outstanding
Empty pin NC ground connection.
Wherein, the power supply circuit includes resistance R1, resistance R2, triode Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with one end of the fuse F1；Institute
The other end for stating resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；The pressure stabilizing
The plus earth of pipe ZD1；The base stage of the triode Q1 is connect with the other end of the resistance R2, the transmitting of the triode Q1
Pole is connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1 respectively, and the capacitor C4's is another
One end ground connection.
Wherein, the protection circuit includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the transmitting of the triode Q3
Pole respectively with one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12 one
End connection, the other end of the resistance R5 are connect with the pwm signal input pin INN of the DC/DC boost chip U1；The electricity
The other end, the other end of the resistance R11 and the other end of the resistance R12 of resistance R10 is grounded；The collection of the triode Q3
Electrode is connect with the cathode of the backlight LED load circuit.
Wherein, the square-wave signal conversion circuit includes resistance R14, diode D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor
One end of C7 is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with
The output pin OUT connection of the DC/DC boost chip U1, the other end of the other end of the resistance R15 and the capacitor C7
It is grounded.
Wherein, the voltage detecting circuit includes resistance R7, resistance R8 and diode D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively,
The other end of the resistance R7 is grounded；The over-voltage of the cathode of the diode D5 and the DC/DC boost chip U1 detect pin
OVP connection；The other end of the resistance R8 is connect with the cathode of the diode D2.
Correspondingly, the embodiment of the invention also provides a kind of LCD displays, comprising:
LCD display and LED backlight drive circuit,
The LED backlight drive circuit is used to control the backlight illumination of the LCD display；
The LED backlight drive circuit includes DC/DC boost chip U1, input terminal CON1, power supply circuit, square-wave signal
Conversion circuit, protection circuit, voltage detecting circuit, backlight LED load circuit, resistance R6, metal-oxide-semiconductor Q2, inductance L1, diode
D2, fuse F1, capacitor C3, resistance R3, diode D1, resistance R4;
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the back
The connection of light source led load circuit, also passes through the fuse F1, the electricity of the power supply circuit and the DC/DC boost chip U1
Source pin VDD connection；The input terminal CON1 also makes can control by the resistance R3 and DC/DC boost chip U1
Pin EA connection；The input terminal CON1 also passes through the diode D1, the resistance R4 and the DC/DC boost chip U1
The INN connection of pwm signal input pin；The protection circuit also passes through the capacitor C3's and DC/DC boost chip U1
Compensation pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, described
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, two pole
Pipe D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through described
Voltage detecting circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and outstanding
Empty pin NC ground connection.
Wherein, the power supply circuit includes resistance R1, resistance R2, triode Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with one end of the fuse F1；Institute
The other end for stating resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；The pressure stabilizing
The plus earth of pipe ZD1；The base stage of the triode Q1 is connect with the other end of the resistance R2, the transmitting of the triode Q1
Pole is connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1 respectively, and the capacitor C4's is another
One end ground connection.
Wherein, the protection circuit includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the transmitting of the triode Q3
Pole respectively with one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12 one
End connection, the other end of the resistance R5 are connect with the pwm signal input pin INN of the DC/DC boost chip U1；The electricity
The other end, the other end of the resistance R11 and the other end of the resistance R12 of resistance R10 is grounded；The collection of the triode Q3
Electrode is connect with the cathode of the backlight LED load circuit.
Wherein, the square-wave signal conversion circuit includes resistance R14, diode D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor
One end of C7 is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with
The output pin OUT connection of the DC/DC boost chip U1, the other end of the other end of the resistance R15 and the capacitor C7
It is grounded.
Wherein, the voltage detecting circuit includes resistance R7, resistance R8 and diode D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively,
The other end of the resistance R7 is grounded；The over-voltage of the cathode of the diode D5 and the DC/DC boost chip U1 detect pin
OVP connection；The other end of the resistance R8 is connect with the cathode of the diode D2.
The implementation of the embodiments of the present invention has the following beneficial effects:
The embodiment of the present invention passes through the inductance L1, the diode D2, the metal-oxide-semiconductor Q2 and DC/DC boosting core
Piece U1 constitutes booster circuit and controls the voltage of the backlight LED load circuit, and is detected by voltage detecting circuit 4 described
The voltage of backlight LED load circuit adjusts the output of the DC/DC boost chip U1, and loads electricity in the backlight LED
Series connection protects circuit 3 and square-wave signal conversion circuit 2 to avoid when the DC/DC boost chip U1 does not work in road, institute
The voltage for stating backlight LED load is uncontrollable, also reduces the cost of conventional driving circuit, extends the use of LCD backlight circuit
Service life.
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 structural schematic diagram of LED backlight drive circuit provided in an embodiment of the present invention；
Fig. 2 is a kind of LED backlight drive circuit figure provided in an embodiment of the present invention；
Fig. 3 is a kind of structural schematic diagram of LCD display provided in an embodiment of the present invention.
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 embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
It referring to Figure 1, is a kind of structural schematic diagram of LED backlight drive circuit provided in an embodiment of the present invention, the electricity
Road includes:
DC/DC boost chip U1, input terminal CON1, power supply circuit 1, square-wave signal conversion circuit 2, protection circuit 3, electricity
Press detection circuit 4, backlight LED load circuit 5, resistance R6, metal-oxide-semiconductor Q2, inductance L1, diode D2, fuse F1, capacitor
C3, resistance R3, diode D1, resistance R4;
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the back
The connection of light source led load circuit, also passes through the fuse F1, the electricity of the power supply circuit and the DC/DC boost chip U1
Source pin VDD connection；The input terminal CON1 also makes can control by the resistance R3 and DC/DC boost chip U1
Pin EA connection；The input terminal CON1 also passes through the diode D1, the resistance R4 and the DC/DC boost chip U1
The INN connection of pwm signal input pin；The protection circuit also passes through the capacitor C3's and DC/DC boost chip U1
Compensation pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, described
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, two pole
Pipe D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through described
Voltage detecting circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and outstanding
Empty pin NC ground connection.
Wherein, the input terminal CON1 is for output voltage (such as 12V voltage), dim signal and the control DC/DC
The working condition of boost chip U1.
The working principle of the LED backlight drive circuit are as follows:
The 12V DC voltage that the power pins VCC of input terminal CON1 is provided is two-way by the fuse F1 points,
It powers all the way by the power supply circuit 1 to the DC/DC boost chip U1, another way passes through the inductance L1, two pole
Pipe D2, the metal-oxide-semiconductor Q2 and the DC/DC boost chip U1 constitute booster circuit.
Wherein, the working principle of the booster circuit specifically:
When metal-oxide-semiconductor Q2 conducting, the 12V voltage by the fuse F1 is by the inductance L1 and described
Metal-oxide-semiconductor Q2, while the inductance L1 stores the energy of its process, the energy when the metal-oxide-semiconductor Q2 is closed, in the inductance L1
It discharges by the diode D2 to the capacitor C8, the backlight LED load circuit 5.The voltage detecting circuit can incite somebody to action
It is supplied to over-voltage detection pin OVP of the Voltage Feedback to the DC/DC boost chip U1 of the backlight LED load circuit 5,
Then, the adjustable output of the output pin OUT of the DC/DC boost chip U1, and determine the conducting of the metal-oxide-semiconductor Q2 and cut
Only, and then the voltage for being supplied to the backlight LED load circuit 5 is controlled.
In addition, to avoid the voltage of the backlight LED load circuit 5 uncontrollable in the embodiment of the present invention, the LED back
Light drive circuit further includes protection circuit 3, and when the DC/DC boost chip U1 does not work, the metal-oxide-semiconductor Q2 is also switched off, though
The voltage that the power pins VCC of the right input terminal CON1 is provided can be supplied directly to the backlight LED load circuit 5,
But since one end of the protection circuit 3 is connect with the cathode of the backlight LED load circuit 5 respectively, the protection circuit 3
Also it is connect with the square-wave signal conversion circuit 2, when the output pin OUT of the DC/DC boost chip U1 is not exported, institute
It states square-wave signal conversion circuit 2 and protects circuit not work so that returning where the backlight LED load circuit 5 with described
Road is open circuit, and then protects the backlight LED load circuit 5.
Implement the embodiment of the present invention the utility model has the advantages that
The embodiment of the present invention passes through the inductance L1, the diode D2, the metal-oxide-semiconductor Q2 and DC/DC boosting core
Piece U1 constitutes the voltage that booster circuit controls the backlight LED load circuit 5, and detects institute by voltage detecting circuit 4
The voltage for stating backlight LED load, adjusts the output of the DC/DC boost chip U1, and in the backlight LED load circuit
Middle series connection protects circuit 3 and square-wave signal conversion circuit 2 to avoid when the DC/DC boost chip U1 does not work, described
The voltage of backlight LED load is uncontrollable.
Fig. 2 is referred to, is a kind of specific LED backlight drive circuit figure provided in an embodiment of the present invention, the circuit packet
Include DC/DC boost chip U1, input terminal CON1, power supply circuit 1, square-wave signal conversion circuit 2, protection circuit 3, voltage detecting
Circuit 4, backlight LED load circuit 5, resistance R6, metal-oxide-semiconductor Q2, inductance L1, diode D2, fuse F1, capacitor C6, capacitor
C1, capacitor C2, capacitor C3, capacitor C9, capacitor C8, capacitor C10, resistance R3, diode D1, resistance R4, diode D1;
Wherein, the power pins VCC of the input terminal CON1 is connect with one end of the fuse F1, the fuse
The other end of F1 is connect with the power supply circuit 1, the electricity of the other end of the power supply circuit 1 and the DC/DC boost chip U1
Source pin VDD connection；The output pin OUT of the DC/DC boost chip U1 respectively with the square-wave signal conversion circuit 2 one
End is connected with one end of the resistance R6, and the other end of the resistance R6 is connect with the grid of the metal-oxide-semiconductor Q2, the metal-oxide-semiconductor
The source electrode of Q2 is grounded, and the drain electrode of the metal-oxide-semiconductor Q2 is connect with the anode of one end of the inductance L1 and the diode D2 respectively；
The other end of the inductance L1 is connect with the other end of the fuse F1；The cathode of the diode D2 respectively with the backlight
The anode of source LED load circuit connects；The cathode of the backlight LED load circuit is connect with one end of the protection circuit,
The other end of the protection circuit is connect with the other end of the square-wave signal conversion circuit 2；
The over-voltage detection pin OVP of the DC/DC boost chip U1 is connect with one end of the voltage detecting circuit 4, institute
The other end for stating voltage detecting circuit 4 is connect with the cathode of the diode D2；
The DC/DC boost chip U1 make can control pin EA respectively with one end of the capacitor C2 and the resistance R3
One end connection；The other end of the capacitor C2 is grounded；The switch of the other end of the resistance R3 and the input terminal CON1
Pin N/F connection；
The compensation pin CMP of the DC/DC boost chip U1 is connect with one end of the capacitor C3；The capacitor C3's is another
One end is connect with one end of the protection circuit 3 and the resistance R4 respectively；
The pwm signal input pin INN of the DC/DC boost chip U1 is also connect with one end of the resistance R4, described
The other end of resistance R4 is connect with the cathode of the diode D1, and the anode of the diode D1 is with the input terminal CON1's
Dim pin connection；
One end of the capacitor C6 is connect with the other end of the fuse F1, the other end ground connection of the capacitor C6；Institute
The anode for stating capacitor C1 is connect with the other end of the fuse F1, the minus earth of the capacitor C1；The one of the capacitor C9
End is connect with the cathode of the diode D2, the other end ground connection of the capacitor C9；The anode of the capacitor C8 and two pole
The cathode of pipe D2 connects, the minus earth of the capacitor C8；The cathode of one end of the capacitor C10 and the diode D2 connect
It connects, the other end ground connection of the capacitor C10.Wherein, the capacitor C6, the capacitor C1, the capacitor C9, the capacitor C8 and
The capacitor C10 is filtered effect to the booster circuit.
Wherein, the power supply circuit 1 includes resistance R1, resistance R2, triode Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with the other end of the fuse F1；
The other end of the resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；It is described steady
The plus earth of pressure pipe ZD1；The base stage of the triode Q1 is connect with the other end of the resistance R2, the hair of the triode Q1
Emitter-base bandgap grading is connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1 respectively, the capacitor C4's
Other end ground connection.
The protection circuit 3 includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the transmitting of the triode Q3
Pole respectively with one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12 one
End connection, the other end of the resistance R5 are connect with the pwm signal input pin INN of the DC/DC boost chip U1；The electricity
The other end, the other end of the resistance R11 and the other end of the resistance R12 of resistance R10 is grounded；The collection of the triode Q3
Electrode is connect with the cathode of the backlight LED load circuit 5.
It is the triode Q3 that crucial protective effect is played in the protection circuit 3, the protection circuit 3 and DC/
DC boost chip U1 works together constant, the concrete operating principle that can also maintain output electric current are as follows: the backlight LED load
The electric current of circuit 5 by the resistance R10, the resistance R11 and the resistance R12 and couples after the triode Q3
Behind ground, voltage drop is had on the resistance R10, the resistance R11 and the resistance R12, for example, set the resistance R10,
Total resistance value after the resistance R11 and resistance R12 is in parallel is Ro, and the electric current of the backlight LED load circuit 5 is Io,
Then as Ro*Io >=0.2V, i.e., when the light modulation pin INN of the described DC/DC boost chip U1 reaches 0.2V, the DC/DC boosting
Chip U1 will adjust the output of its output pin OUT, and the Io is made to maintain a constant value.
The square-wave signal conversion circuit 2 includes resistance R14, diode D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor
One end of C7 is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with
The output pin OUT connection of the DC/DC boost chip U1, the other end of the other end of the resistance R15 and the capacitor C7
It is grounded.
The voltage detecting circuit 4 includes resistance R7, resistance R8 and diode D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively,
The other end of the resistance R7 is grounded；The over-voltage of the cathode of the diode D5 and the DC/DC boost chip U1 detect pin
OVP connection；The other end of the resistance R8 is connect with the cathode of the diode D2.
In addition, being input to described after the light modulation pin ADJ of the input terminal CON1 is subjected to external dim signal
The pwm signal input pin INN of DC/DC boost chip U1.The backlight LED load circuit 5 can be connected by two paths of LED parallel connection
It connects, the every road backlight LED branch constituted after at least one LED series connection can pass through input terminal CON2 and input terminal respectively
It is in parallel after the 1st pin of CON3 and the 2nd pin, for example, the backlight LED load circuit is shone by two 5 shown in Fig. 2
(specially LED11, LED12, LED13, LED14, LED15 are constituted after the concatenated branch circuit parallel connection of diode (LED)；LED21,
LED22, LED23, LED24, LED25).
The working principle of the voltage detecting circuit 4 are as follows:
The resistance R7 and resistance R8 detects output voltage, and divides, i.e., by the backlight LED load circuit 5
Input voltage partial pressure after be used as voltage detection signal, for example, if protection point voltage be 1.5V, as Vo* (R7/ (R7+
R8)) >=1.5V when, the output voltage of the DC/DC boost chip U1 will be reduced, to maintain output voltage in the range of setting
It is interior.
The driving of LED backlight described in the embodiment of the present invention further includes resistance R13, resistance R16, capacitor C5, wherein the electricity
Hold C5 to be used to filter the voltage detecting circuit, the size of the resistance R13 and resistance R16 control signal stablize institute
State voltage detection signal.
Implement the embodiment of the present invention the utility model has the advantages that
The embodiment of the present invention passes through the inductance L1, the diode D2, the metal-oxide-semiconductor Q2 and DC/DC boosting core
Piece U1 constitutes the voltage that booster circuit controls the backlight LED load circuit 5, and detects institute by voltage detecting circuit 4
The voltage for stating backlight LED load circuit 5 adjusts the output of the DC/DC boost chip U1, and the backlight LED is negative
It carries circuit 5 and connects the triode Q3 and diode D4 to avoid when the DC/DC boost chip U1 does not work, institute
The voltage for stating backlight LED load circuit 5 is uncontrollable, also reduces the cost of conventional driving circuit, extends LCD backlight circuit
Service life.
Referring to Fig. 3 is a kind of structural schematic diagram of LCD display provided in an embodiment of the present invention, the LCD display
Including LCD display 01 and LED backlight drive circuit 02,
Wherein the LED backlight drive circuit 02 is used to control the backlight illumination of the LCD display 01；
The LED backlight drive circuit 02 includes DC/DC boost chip U1, input terminal CON1, power supply circuit, square wave letter
Number conversion circuit, protection circuit, voltage detecting circuit, backlight LED load circuit, resistance R6, metal-oxide-semiconductor Q2, inductance L1, two poles
Pipe D2, fuse F1, capacitor C3, resistance R3, diode D1, resistance R4;
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the back
The connection of light source led load circuit, also passes through the fuse F1, the electricity of the power supply circuit and the DC/DC boost chip U1
Source pin VDD connection；The input terminal CON1 also makes can control by the resistance R3 and DC/DC boost chip U1
Pin EA connection；The input terminal CON1 also passes through the diode D1, the resistance R4 and the DC/DC boost chip U1
The INN connection of pwm signal input pin；The protection circuit also passes through the capacitor C3's and DC/DC boost chip U1
Compensation pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, described
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, two pole
Pipe D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through described
Voltage detecting circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and outstanding
Empty pin NC ground connection.
Wherein, the power supply circuit includes resistance R1, resistance R2, triode Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with the other end of the fuse F1；
The other end of the resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；It is described steady
The plus earth of pressure pipe ZD1；The base stage of the triode Q1 is connect with the other end of the resistance R2, the hair of the triode Q1
Emitter-base bandgap grading is connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1 respectively, the capacitor C4's
Other end ground connection.
Wherein, the protection circuit includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the transmitting of the triode Q3
Pole respectively with one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12 one
End connection, the other end of the resistance R5 are connect with the pwm signal input pin INN of the DC/DC boost chip U1；The electricity
The other end, the other end of the resistance R11 and the other end of the resistance R12 of resistance R10 is grounded；The collection of the triode Q3
Electrode is connect with the cathode of the backlight LED load circuit.
Wherein, the square-wave signal conversion circuit includes resistance R14, diode D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor
One end of C7 is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with
The output pin OUT connection of the DC/DC boost chip U1, the other end of the other end of the resistance R15 and the capacitor C7
It is grounded.
Wherein, the voltage detecting circuit includes resistance R7, resistance R8 and diode D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively,
The other end of the resistance R7 is grounded；The over-voltage of the cathode of the diode D5 and the DC/DC boost chip U1 detect pin
OVP connection；The other end of the resistance R8 is connect with the cathode of the diode D2.
The working principle of the LCD display are as follows:
Backlight of the LED backlight drive circuit 02 using LED as the LCD display, the LED backlight driving
Circuit controls the backlight LED by the DC/DC boost chip U1, the metal-oxide-semiconductor Q2 and the voltage detecting circuit 4 and bears
The voltage of circuit 5 is carried in the range of setting；The backlight LED load circuit 5 is avoided directly to connect by the triode Q3
It is uncontrollable by the voltage provided from the input terminal CON1；By in the resistance R10, the resistance R11 and described
On resistance R12 generate voltage drop control the backlight LED load circuit 5 electric current it is constant, for example, setting the resistance R10, institute
Total resistance value after stating resistance R11 and resistance R12 parallel connection is Ro, and the electric current of the backlight LED load circuit 5 is Io, then
As Ro*Io >=0.2V, i.e., when the light modulation pin INN of the described DC/DC boost chip U1 reaches 0.2V, the DC/DC boosting core
Piece U1 will adjust the output of its output pin OUT, and the Io is made to maintain constant value.
The implementation of the embodiments of the present invention has the following beneficial effects:
The embodiment of the present invention controls to adjust the brightness of the display screen by the LED backlight drive circuit, can be to avoid
The voltage of the backlight LED load is uncontrollable, reduces the cost of conventional driving circuit as backlight using LED, simultaneously
Extend the service life of LCD backlight circuit.
Those of ordinary skill in the art will appreciate that realizing all or part of the process in above-described embodiment method, being can be with
Relevant hardware is instructed to complete by computer program, the program can be stored in a computer-readable storage medium
In, the program is when being executed, it may include such as the process of the embodiment of above-mentioned each method.Wherein, the storage medium can be magnetic
Dish, CD, read-only memory (Read-Only Memory, ROM) or random access memory (Random Access
Memory, RAM) etc..
The above disclosure is only the preferred embodiments of the present invention, cannot limit the right model of the present invention with this certainly
It encloses, therefore equivalent changes made in accordance with the claims of the present invention, is still within the scope of the present invention.
Claims (8)
1. a kind of LED backlight drive circuit, which is characterized in that including DC/DC boost chip U1, input terminal CON1, power supply electricity
Road, square-wave signal conversion circuit, protection circuit, voltage detecting circuit, backlight LED load circuit, resistance R6, metal-oxide-semiconductor Q2, electricity
Feel L1, diode D2, fuse F1, capacitor C3, resistance R3, diode D1, resistance R4；
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the backlight
LED load circuit connection, is also drawn by the power supply of the fuse F1, the power supply circuit and the DC/DC boost chip U1
Foot VDD connection；The input terminal CON1 also by the resistance R3 and the DC/DC boost chip U1 make can control pin
EA connection；The input terminal CON1 is also by the diode D1, the resistance R4 with the DC/DC boost chip U1's
The INN connection of pwm signal input pin；The protection circuit also passes through the benefit of the capacitor C3 and the DC/DC boost chip U1
Repay pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, the guarantor
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, the diode
D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through the electricity
Pressure detection circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and hanging
Pin NC ground connection；
The protection circuit includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the emitter point of the triode Q3
Do not connect with one end of one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12
It connects, the other end of the resistance R5 is connect with the pwm signal input pin INN of the DC/DC boost chip U1；The resistance
The other end of the other end of R10, the other end of the resistance R11 and the resistance R12 is grounded；The current collection of the triode Q3
Pole is connect with the cathode of the backlight LED load circuit.
2. circuit as described in claim 1, which is characterized in that the power supply circuit includes resistance R1, resistance R2, triode
Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with one end of the fuse F1；The electricity
The other end of resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；The voltage-stabiliser tube ZD1
Plus earth；The base stage of the triode Q1 is connect with the other end of the resistance R2, the emitter point of the triode Q1
It is not connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1, the other end of the capacitor C4
Ground connection.
3. circuit as claimed in claim 1 or 2, which is characterized in that the square-wave signal conversion circuit includes resistance R14, two
Pole pipe D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor C7
One end is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with it is described
The other end of the output pin OUT connection of DC/DC boost chip U1, the other end of the resistance R15 and the capacitor C7 connect
Ground.
4. circuit as claimed in claim 3, which is characterized in that the voltage detecting circuit includes resistance R7, resistance R8 and two
Pole pipe D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively, described
The other end of resistance R7 is grounded；The over-voltage detection pin OVP of the cathode of the diode D5 and the DC/DC boost chip U1 connect
It connects；The other end of the resistance R8 is connect with the cathode of the diode D2.
5. a kind of LCD display, which is characterized in that including LCD display and LED backlight drive circuit,
Wherein, the LED backlight drive circuit is used to control the backlight illumination of the LCD display；
The LED backlight drive circuit includes DC/DC boost chip U1, input terminal CON1, power supply circuit, square-wave signal conversion
Circuit, protection circuit, voltage detecting circuit, backlight LED load circuit, resistance R6, metal-oxide-semiconductor Q2, inductance L1, diode D2,
Fuse F1, capacitor C3, resistance R3, diode D1, resistance R4；
Wherein, the input terminal CON1 passes through the fuse F1, the inductance L1, the diode D2 and the backlight
LED load circuit connection, is also drawn by the power supply of the fuse F1, the power supply circuit and the DC/DC boost chip U1
Foot VDD connection；The input terminal CON1 also by the resistance R3 and the DC/DC boost chip U1 make can control pin
EA connection；The input terminal CON1 is also by the diode D1, the resistance R4 with the DC/DC boost chip U1's
The INN connection of pwm signal input pin；The protection circuit also passes through the benefit of the capacitor C3 and the DC/DC boost chip U1
Repay pin CMP connection；The output pin OUT of the DC/DC boost chip U1 passes through the square-wave signal conversion circuit, the guarantor
Protection circuit is connect with the backlight LED load circuit, while also passing through the resistance R6, the metal-oxide-semiconductor Q2, the diode
D2 is connect with the backlight LED load circuit；The over-voltage detection pin OVP of the DC/DC boost chip U1 passes through the electricity
Pressure detection circuit is connect with the backlight LED load circuit；The grounding pin GND of the DC/DC boost chip U1 and hanging
Pin NC ground connection；
The protection circuit includes triode Q3, resistance R5, resistance R10, resistance R11, resistance R12,
Wherein, the base stage of the triode Q3 is connect with the square-wave signal conversion circuit, the emitter point of the triode Q3
Do not connect with one end of one end of the resistance R5, one end of the resistance R10, one end of the resistance R11 and the resistance R12
It connects, the other end of the resistance R5 is connect with the pwm signal input pin INN of the DC/DC boost chip U1；The resistance
The other end of the other end of R10, the other end of the resistance R11 and the resistance R12 is grounded；The current collection of the triode Q3
Pole is connect with the cathode of the backlight LED load circuit.
6. LCD display as claimed in claim 5, which is characterized in that the power supply circuit includes resistance R1, resistance R2, three
Pole pipe Q1, voltage-stabiliser tube ZD1, capacitor C4,
Wherein, one end of the resistance R1 and one end of the resistance R2 are connect with one end of the fuse F1；The electricity
The other end of resistance R1 is connect with the collector of the cathode of the voltage-stabiliser tube ZD1 and the triode Q1 respectively；The voltage-stabiliser tube ZD1
Plus earth；The base stage of the triode Q1 is connect with the other end of the resistance R2, the emitter point of the triode Q1
It is not connect with the power pins VDD of one end of the capacitor C4 and the DC/DC boost chip U1, the other end of the capacitor C4
Ground connection.
7. LCD display as claimed in claim 6, which is characterized in that the square-wave signal conversion circuit include resistance R14,
Diode D4, resistance R15, capacitor C7；
Wherein, one end of the resistance R14, the cathode of the diode D4, one end of the resistance R15, the capacitor C7
One end is connect with the base stage of the triode Q3；The anode of the other end of the resistance R14 and the diode D4 with it is described
The other end of the output pin OUT connection of DC/DC boost chip U1, the other end of the resistance R15 and the capacitor C7 connect
Ground.
8. LCD display as claimed in claim 7, which is characterized in that the voltage detecting circuit includes resistance R7, resistance R8
With diode D5,
Wherein, one end of the resistance R7 is connect with one end of the anode of the diode D5 and the resistance R8 respectively, described
The other end of resistance R7 is grounded；The over-voltage detection pin OVP of the cathode of the diode D5 and the DC/DC boost chip U1 connect
It connects；The other end of the resistance R8 is connect with the cathode of the diode D2.
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| CN201410114905.1A CN104952398B (en) | 2014-03-25 | 2014-03-25 | A kind of LED backlight drive circuit and LCD display |
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| CN201410114905.1A CN104952398B (en) | 2014-03-25 | 2014-03-25 | A kind of LED backlight drive circuit and LCD display |
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| CN104952398B true CN104952398B (en) | 2019-02-05 |
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| CN106409239B (en) * | 2016-09-09 | 2019-11-26 | 广州视源电子科技股份有限公司 | A kind of LED backlight drive circuit |
| 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 |
| CN109637469A (en) * | 2019-02-20 | 2019-04-16 | 昆山弘锦威电子有限公司 | Backlight regulating circuit |
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| CN104952398A (en) | 2015-09-30 |
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