CN109862292A - A constant current control circuit and TV set - Google Patents
A constant current control circuit and TV set Download PDFInfo
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- CN109862292A CN109862292A CN201910245559.3A CN201910245559A CN109862292A CN 109862292 A CN109862292 A CN 109862292A CN 201910245559 A CN201910245559 A CN 201910245559A CN 109862292 A CN109862292 A CN 109862292A
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Abstract
The embodiment of the invention discloses a kind of constant-current control circuit and television sets.The constant-current control circuit includes that the input terminal of ON-OFF control circuit connects to power supply, output end is connect with the anode of the first LED light group, controlled end is connect with the output end of single- stage PFC control circuit, the cathode of first LED light group is connect with matrix current adjustment circuit, the sampling end of over-voltage adjustment circuit is connect with the first LED light group, the output end of over-voltage adjustment circuit is connect with the feedback end of single- stage PFC control circuit, the anode of second LED light group is connect with matrix current adjustment circuit, and the cathode of the second LED light group is connect with ON-OFF control circuit.For the embodiment of the present invention by the connection type of optimization constant-current control circuit, realizing reduces line cost, improves power-efficient, reduces the ripple current of backlight, improves the stability of backlight work, can match the demand of any number of channels of backlight.
Description
Technical field
The present embodiments relate to power supply control technology field more particularly to a kind of constant-current control circuits and television set.
Background technique
Using LED light bar as backlight in LED liquid crystal television, make LED liquid crystal television fuselage thickness, energy consumption, environmental protection,
Service life and color etc. are advantageously compared to common TV.
The power supply of conventional television is powered to LED light bar, using first passing through PFC (Power Factor
Correction, PFC) circuit is corrected voltage, and constant pressure, which is carried out, using ac-dc conversion circuit turns
It changes, by the 24V constant voltage source of output by being powered to LED backlight lamp bar after BOOST boosting inverter.Conventional power source power supply
The problem of mode is the cost input of the low and additional pfc circuit of the transfer efficiency of power supply, while in order to meet LED backlight
The constant current demand of item, and increase the cost needs of constant current plate.For disadvantages described above problem, it is proposed that controlled using single- stage PFC
Circuit realizes constant current output, and without the two times transfer that boosts, voltage directly carries out AC-DC after single- stage PFC control circuit
The constant pressure of translation circuit is converted.But single- stage PFC control circuit carries out structure chart such as Fig. 1 of constant current output to LED backlight lamp bar
Shown, each LED light bar voltage needs that connect of the single- stage PFC control circuit output in constant-current control circuit are consistent, and every
A LED light bar requires a constant-current circuit and is controlled, and such mode increases the cost of constant current plate, and constant current plate damages
Consume that larger, temperature rise is higher, while relatively narrow to the matching range of LED light bar, such as the two string LED light bars of 70V and 77V just can not be into
Row matching.
Summary of the invention
The embodiment of the present invention provides a kind of constant-current control circuit and television set, to realize reduction line cost, reduces constant current
Loss, improve power-efficient, meanwhile, reduce the ripple current of backlight, improve the stability of backlight work, can match
The demand of any number of channels of backlight.
In a first aspect, the constant-current control circuit includes single-stage the embodiment of the invention provides a kind of constant-current control circuit
PFC control circuit, ON-OFF control circuit, the first LED light group, over-voltage adjustment circuit, matrix current adjustment circuit and the second LED light group；
The input terminal of the ON-OFF control circuit connects to power supply, the output end of the ON-OFF control circuit and first LED light group
Anode connection, the controlled end of the ON-OFF control circuit connect with the output end of the single- stage PFC control circuit, described first
The cathode of LED light group is connect with the matrix current adjustment circuit, the sampling end of the over-voltage adjustment circuit and first LED light group
Connection, the output end of the over-voltage adjustment circuit are connect with the feedback end of the single- stage PFC control circuit, second LED light
The anode of group is connect with the matrix current adjustment circuit, and the cathode of second LED light group is connect with the ON-OFF control circuit；
The ON-OFF control circuit, for giving the first LED after the output voltage filtering by the ON-OFF control circuit
Lamp group is powered；It is also used to receive the electric current of the second LED light group output and is back to the ON-OFF control circuit；
The matrix current adjustment circuit, the second LED light group described in the current control for being exported according to first LED light group
Input current.
Further, the ON-OFF control circuit includes Half bridge rectifier circuit and flyback transformer；The Half bridge rectifier electricity
Road includes first diode, the second diode, first capacitor, the second capacitor, third capacitor, first resistor and second resistance；Institute
The anode for stating first diode is connect with the output end of the flyback transformer, for receiving the electricity of the flyback transformer output
Pressure, the cathode of the first diode connect with the first end of the third capacitor, the second end of the first resistor with it is described
The first end of first capacitor connects, and the first end of the first resistor is in parallel with the second end of the first capacitor and described first
Between the positive electrode and negative electrode of diode, the anode of second diode and the cathode of second LED light group and described the
The second end of three capacitors is connected, for receiving electric current of the cathode of second LED light group by the third capacitor filtering, institute
The cathode for stating the second diode is connect with the output end of the flyback transformer, the second end of the second resistance and described second
The first end of capacitor connects, and the first end of the second resistance is in parallel with the second end of second capacitor and the two or two pole
Between the positive electrode and negative electrode of pipe.
Further, the over-voltage adjustment circuit includes third diode, the 4th resistance, the 5th resistance and the 4th capacitor；
The input terminal of the output end of the over-voltage adjustment circuit and adjuster connects, and the one of the output end of the adjuster and photo-coupler
End connection, the other end of the photo-coupler are connect with the feedback end of the single- stage PFC control circuit, the over-voltage adjustment circuit
For exporting the voltage of first LED light group detected, and by the Voltage Feedback of first LED light group to adjuster,
The voltage of first LED light group is converted into electric current by the photo-coupler by the adjuster, and by the current feedback
To the feedback end of the single- stage PFC control circuit.
Further, the matrix current adjustment circuit includes amplifier tube, operational amplifier, RC filter circuit and sampling resistor；
The input terminal of the amplifier tube is connect with the cathode of first LED light group, the output end of the amplifier tube and sampling electricity
The first end of resistance connects, and the second end of the sampling resistor is connect with the anode of second LED light group, the operational amplifier
It is in parallel with the RC filter circuit between the amplifier tube and the first end of the sampling resistor.
Further, the constant-current control circuit further includes reference voltage circuit, the output end of the reference voltage circuit
It is connect with the matrix current adjustment circuit, the input terminal of the reference voltage circuit is for receiving pwm signal, the adjustment of Xiang Suoshu electric current
Circuit provides reference voltage.
Further, the constant-current control circuit further includes the smooth adjustment circuit of brightness, the brightness smooth adjustment circuit
It is connect with the matrix current adjustment circuit；The electric current that the brightness smooth adjustment circuit exports first LED light group takes
Sample, and it is converted into voltage signal, the voltage signal is compared with reference voltage, according to comparison result adjustment described first
The brightness of LED light group.
Further, the constant-current control circuit further includes EMI filter circuit and power supply circuit, the EMI filter circuit
Output end connect with the input terminal of the ON-OFF control circuit, the access of the input terminal of the EMI filter circuit connects to power supply,
The output end of the power supply circuit is connected with the power end of the single- stage PFC control circuit.
Further, the cathode of first LED light group is connect with the first end of the matrix current adjustment circuit, the electric current
The second end of adjustment circuit is grounded, and the anode of second LED light group connects with the second end ground terminal of the matrix current adjustment circuit
It connects.
Further, first LED light group includes multiple concatenated LED light, and second LED light group includes multiple strings
The LED light of connection.
Second aspect, the embodiment of the invention also provides a kind of television sets, including such as first aspect of embodiment of the present invention institute
The constant-current control circuit stated.
The embodiment of the present invention is connected to power supply by the input terminal of ON-OFF control circuit, the output end of ON-OFF control circuit with
The anode connection of first LED light group, the controlled end of ON-OFF control circuit are connect with the output end of single- stage PFC control circuit, and first
The cathode of LED light group is connect with matrix current adjustment circuit, and the sampling end of over-voltage adjustment circuit is connect with the first LED light group, over-voltage tune
The output end of whole circuit is connect with the feedback end of single- stage PFC control circuit, and anode and the matrix current adjustment circuit of the second LED light group connect
It connects, the cathode of the second LED light group is connect with ON-OFF control circuit.ON-OFF control circuit is used for the output electricity of ON-OFF control circuit
It is powered after filters pressing wave to the first LED light group；It is also used to receive the electric current of the second LED light group output and is back to switch control
Circuit；The input current for the second LED light group of current control that matrix current adjustment circuit is used to be exported according to the first LED light group.In this way
Method optimize the connection type of constant-current control circuit, realizing reduces line cost, reduces the loss of constant current, improves power supply
Efficiency, meanwhile, the ripple current of backlight is reduced, the stability of backlight work is improved, any port number of backlight can be matched
The demand of amount.
Detailed description of the invention
Fig. 1 is the structure chart that single- stage PFC control circuit carries out constant current output to LED backlight lamp bar；
Fig. 2 is a kind of structural schematic diagram of constant-current control circuit provided in an embodiment of the present invention；
Fig. 3 is a kind of circuit structure diagram of constant-current control circuit provided in an embodiment of the present invention.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawing to of the invention specific real
Example is applied to be described in further detail.It is understood that specific embodiment described herein is used only for explaining the present invention,
Rather than limitation of the invention.
It also should be noted that only the parts related to the present invention are shown for ease of description, in attached drawing rather than
Full content.It should be mentioned that some exemplary embodiments are described before exemplary embodiment is discussed in greater detail
At the processing or method described as flow chart.Although operations (or step) are described as the processing of sequence by flow chart,
It is that many of these operations can be implemented concurrently, concomitantly or simultaneously.In addition, the sequence of operations can be by again
It arranges.The processing can be terminated when its operations are completed, it is also possible to have the additional step being not included in attached drawing.
The processing can correspond to method, function, regulation, subroutine, subprogram etc..
Fig. 2 show a kind of structural schematic diagram of constant-current control circuit provided in an embodiment of the present invention, and the present embodiment can fit
For controlling the case where LED light group electric current is in steady state, the specific structure of the constant-current control circuit 100 is as follows:
Including single- stage PFC control circuit 110, ON-OFF control circuit 120, the first LED light group 130, over-voltage adjustment circuit
140, matrix current adjustment circuit 150 and the second LED light group 160；
The input terminal of the ON-OFF control circuit 120 connects to power supply, the output end of the ON-OFF control circuit 120 and institute
State the anode connection of the first LED light group 130, the controlled end of the ON-OFF control circuit 120 and the single- stage PFC control circuit
110 output end connection, the cathode of first LED light group 130 are connect with the matrix current adjustment circuit 150, the over-voltage tune
The sampling end of whole circuit 140 is connect with first LED light group 130, the output end and the list of the over-voltage adjustment circuit 140
The feedback end connection of grade PFC control circuit 110, anode and the matrix current adjustment circuit 150 of second LED light group 160 connect
It connects, the cathode of second LED light group 160 is connect with the ON-OFF control circuit 120；
The ON-OFF control circuit 120, for after the output voltage of the ON-OFF control circuit 120 is filtered to described the
One LED light group 130 is powered；It is also used to receive the electric current that second LED light group 160 exports and is back to the switch control
Circuit 120 processed；
The matrix current adjustment circuit 150, second described in the current control for being exported according to first LED light group 130
The input current of LED light group 160.
Wherein, first LED light group 130 includes multiple concatenated LED light, and second LED light group 160 includes multiple
Concatenated LED light.The quantity of specific LED light can be configured according to the actual demand of those skilled in the art, and the present invention is real
Example is applied to power by using mode concatenated between lamp group, keep flow through LED light group electric current it is constant under the premise of, realize herein
The demand of any number of LED light can be matched.
Specifically, ON-OFF control circuit 120 exports electric current under the control of single- stage PFC control circuit 110, to the first LED light
130 power supply of group, the voltage of the first LED light group 130 feeds back to single- stage PFC control circuit 110 through over-voltage adjustment circuit 140, when the
When the overtension of one LED light group 130, the voltage of the first LED light group 130 feeds back to single- stage PFC control through over-voltage adjustment circuit 140
The voltage that circuit 110 processed, single- stage PFC control circuit 110 and then control switch control circuit 120 export reduces, so that the
The electric current of one LED light group 130 output is constant.Optionally, the ON-OFF control circuit 120 in the embodiment of the present invention can choose setting
Being includes Half bridge rectifier circuit and flyback transformer.Illustratively, flyback transformer single- stage PFC control circuit 110 control under,
Output voltage is powered after Half bridge rectifier filters to the first LED light group 130, and the voltage of the first LED light group 130 adjusts electricity through over-voltage
Road 140 feeds back to single- stage PFC control circuit 110, and when the overtension of the first LED light group 130, which adjusts electricity through over-voltage
Road 140 feeds back to single- stage PFC control circuit 110, and the voltage drop of flyback transformer output is controlled by single- stage PFC control circuit 110
It is low, so that flowing through the current reduction of the first LED light group 130.Electricity is controlled using 110 control switch of single- stage PFC control circuit
Road 120 saves PCB surface product and cost, improves electrical source power factor because eliminating high-voltage electrolytic capacitor.
Further, the cathode of first LED light group 130 is connect with the first end of the matrix current adjustment circuit 150, institute
State the second end ground connection of matrix current adjustment circuit 150, anode and the matrix current adjustment circuit 150 of second LED light group 160
The connection of second end ground terminal.
Specifically, the second LED light group 160 of connecting again after 130 series current adjustment circuit 150 of the first LED light group, so that stream
The electric current of the electric current and the first LED light group 130 of crossing the second LED light group 160 is consistent, the electric current that the second last LED light group 160 flows out
It is back to ON-OFF control circuit 120.In the prior art, if two groups of LED light groups electricity that traditional single stage PFC control circuit 110 connects
Pressure needs consistent, and two matrix current adjustment circuits 150 is needed to control every group of LED light group respectively, such higher cost, constant current loss compared with
Greatly, temperature rise is higher, and relatively narrow to the matching range of lamp group, such as two cluster of lamps, ornamental items of 70V and 77V can not just match.The present invention is real
The technical solution for applying example to solve this problem, is first connect with the first LED light group 130, then lead to by single- stage PFC control circuit 110
Overcurrent adjustment circuit 150 is connected the second LED light group 160, as long as matrix current adjustment circuit 150 is allowed to control the electricity of every group of LED light group
Stream is in steady state, accordingly even when the voltage phase difference of every group of LED light group can also work normally greatly very much, simplifies electric current adjustment electricity
Road 150 and over-voltage adjustment circuit 140, while reducing filter capacitor quantity in specific implementation circuit diagram, then reduce LED perseverance
The loss of flow control circuit 100 reduces line cost, and a variety of screen bodies of matching can be facilitated by improving power-efficient again.In addition, passing through
The electric current of first LED light group 130 passes through matrix current adjustment circuit 150, so that flowing through the current ripples of LED light group reduces, improves
The stability of LED light group work.
Further, the matrix current adjustment circuit 150 includes amplifier tube, operational amplifier, RC filter circuit and sampling electricity
Resistance；The input terminal of the amplifier tube is connect with the cathode of first LED light group 130, the output end of the amplifier tube with it is described
The first end of sampling resistor connects, and the second end of the sampling resistor is connect with the anode of second LED light group 160, described
Operational amplifier is in parallel with the RC filter circuit between the amplifier tube and the first end of the sampling resistor.The constant current
Control circuit 100 further includes reference voltage circuit, and the output end of the reference voltage circuit and the matrix current adjustment circuit 150 connect
It connects, the input terminal of the reference voltage circuit provides reference voltage for receiving pwm signal, Xiang Suoshu matrix current adjustment circuit 150.
Wherein, the small ripple voltage of low frequency that constant-current control circuit 100 exports is larger, and traditional current constant control mode can not be examined
Ripple voltage is measured, so that the LED light ripple current of output is also larger, is adopted in matrix current adjustment circuit 150 in the embodiment of the present invention
Operational amplifier may be implemented after amplifying small ripple voltage, control constant-current source, so that the constant current ripple of output
It is lower.
Specifically, after reference voltage circuit generates higher reference voltage, being conveyed to electricity when pwm signal is high level
It flows adjustment circuit 150 and is used as reference voltage, operation can be made to put using reference voltage as reference by the voltage of sampling resistor at this time
The output adjustment amplifier tube of big device, so that its electric current passed through increases, then the voltage of sampling resistor is increased to reference voltage, finally
The brightness of the LED light of LED light group brightens；When pwm signal is low level 0V, it is 0V that reference voltage circuit, which generates reference voltage,
It is conveyed to reference voltage of the operational amplifier as operational amplifier after generating the reference voltage of 0V, passes through sampling resistor at this time
Voltage can make the output adjustment amplifier tube of operational amplifier using reference voltage 0V as reference, so that its electric current passed through becomes smaller,
Then down to reference voltage, the brightness of the LED light of last LED light group is dimmed for the voltage drop of sampling resistor.
When the duty ratio of pwm signal high level becomes larger, the reference voltage raising that reference voltage circuit generates is conveyed to fortune
Calculate amplifier, as the reference voltage of operational amplifier, at this time by the voltage of sampling resistor can using reference voltage as referring to,
Make the output adjustment amplifier tube of operational amplifier, so that its electric current passed through increases, then the voltage of sampling resistor is increased to benchmark
Voltage finally makes the brightness of the LED light of LED light group brighten；Similarly, when the duty ratio of pwm signal high level becomes smaller, LED
The brightness of the LED light of lamp group is dimmed.
Further, the constant-current control circuit 100 further includes EMI filter circuit and power supply circuit, the EMI filtered electrical
The output end on road is connect with the input terminal of the ON-OFF control circuit 120, the input terminal access of the EMI filter circuit and power supply
Connection, the output end of the power supply circuit are connected with the power end of the single- stage PFC control circuit 110.
Specifically, power supply circuit is controlled by optocoupler, so that single-stage when the enable signal of power supply circuit is high level
PFC control circuit 110 is started to work, and control switch control circuit 120 exports the first LED light group of current direction 130, electric current tune
Whole circuit 150 and the second LED light group 160.The first LED light group 130 and sampling is connected in series in amplifier tube in matrix current adjustment circuit 150
Resistance flows through sampling resistor by the electric current of the first LED light group 130, and the small voltage that sampling resistor samples feeds back to operation
Output control amplifier tube, amplifier tube always work in after amplifier, operational amplifier and reference voltage differential comparison operation amplifier
Linear zone, so that the electric current precision by the first LED light group 130 is constant, to reduce the electricity for flowing through the first LED light group 130
Flow liner wave reduces the current loss of LED light group, the power-efficient improved, meanwhile, the connection type of tandem makes LED
The pressure difference of lamp group can work normally very big, can facilitate a variety of screen bodies of matching, reduce line cost.When making for power supply circuit
When energy signal is low level, power supply circuit is controlled by optocoupler and stops power supply, so that the stopping of single- stage PFC control circuit 110
Work, and control switch control circuit 120 also stops working, the obstructed overcurrent of LED light group, LED light group is in OFF state, and
Single- stage PFC control circuit 110 stops working, and matrix current adjustment circuit 150 also stops working, and reduces stand-by power consumption.
It should be noted that it is normal to manage IC in primary side single- stage PFC control circuit 110 when booting enable signal is high level
Under working condition, pwm signal directly controls the matrix current adjustment circuit 150 and LED light group on multiple side, so that the LED light brightness of output
Smooth adjustable, primary side power management chip the operation is stable, without with pwm signal repeat switch machine.When standby enable signal is low
When level, control primary side single- stage PFC control circuit 110 manages IC and stops working, and is then powered off the electric current by LED light group, greatly
Stand-by power consumption is reduced greatly, meets user demand.In addition, power management IC mentioned herein is using the digital control of JPX
IC, model JP0010J, single- stage PFC control circuit 110 directly control 120 output constant current source of ON-OFF control circuit, eliminate high pressure
Electrolytic capacitor improves electrical source power factor and efficiency, reduces costs.
Further, the constant-current control circuit 100 further includes the smooth adjustment circuit of brightness, the brightness smooth adjustment electricity
Road is connect with the matrix current adjustment circuit 150；The electricity that the brightness smooth adjustment circuit exports first LED light group 130
Stream is sampled, and is converted into voltage signal, and the voltage signal is compared with reference voltage, is adjusted according to comparison result
The brightness of first LED light group 130.
By the way that brightness smooth adjustment circuit is arranged, it can realize that LED luminance is smoothly adjustable when user carries out PWM light modulation, and
The ripple current by LED light bar is reduced, stand-by power consumption is reduced.
The embodiment of the present invention is connected to power supply by the input terminal of ON-OFF control circuit 120, ON-OFF control circuit 120 it is defeated
Outlet is connect with the anode of the first LED light group 130, controlled end and the single- stage PFC control circuit 110 of ON-OFF control circuit 120
Output end connection, the cathode of the first LED light group 130 are connect with matrix current adjustment circuit 150, the sampling end of over-voltage adjustment circuit 140
It being connect with the first LED light group 130, the output end of over-voltage adjustment circuit 140 is connect with the feedback end of single- stage PFC control circuit 110,
The anode of second LED light group 160 is connect with matrix current adjustment circuit 150, the cathode and ON-OFF control circuit of the second LED light group 160
120 connections.ON-OFF control circuit 120 is used for after the output voltage filtering by ON-OFF control circuit 120 to the first LED light group 130
It is powered；It is also used to receive the electric current of the second LED light group 160 output and is back to ON-OFF control circuit 120；Electric current adjustment electricity
The input current for the second LED light group of current control 160 that road 150 is used to be exported according to the first LED light group 130.Such method
The connection type of constant-current control circuit is optimized, realizing reduces line cost, and the loss of constant current is reduced, power-efficient is improved,
Meanwhile the ripple current of backlight is reduced, the stability of backlight work is improved, the need of any number of channels of backlight can be matched
It asks.
It is a kind of circuit structure diagram of constant-current control circuit provided in an embodiment of the present invention shown in Fig. 3.
As shown in figure 3, power supply is conveyed to flyback transformer T1 after EMI is filtered and rectifies BD filtering, controlled in single- stage PFC
9 foot output control switch pipe Q1 of circuit U 1, and then transformer T1 concussion is controlled, so that T1 output voltage, rectified exporting
Give the first LED light group after D1 and capacitor C3 filtering (the first LED light group may include LED1 ... LED1n).Illustratively, described
ON-OFF control circuit includes Half bridge rectifier circuit and flyback transformer；The Half bridge rectifier circuit includes first diode D1,
Two diode D2, first capacitor C1, the second capacitor C2, third capacitor C3, first resistor R1 and second resistance R2；Described 1st
The anode of pole pipe D1 is connect with the output end of the flyback transformer T1, for receiving the electricity of the flyback transformer T1 output
Pressure, the cathode of the first diode D1 are connect with the first end of the third capacitor C3, the second end of the first resistor R1
It is connect with the first end of the first capacitor C1, the second end of the first end of the first resistor R1 and the first capacitor C1 are simultaneously
Between connection and the positive electrode and negative electrode of the first diode D1, anode and second LED light group of the second diode D2
Cathode and the second end of the third capacitor C3 be connected, for receiving the cathode of second LED light group by described the
The electric current of three capacitor C3 filtering, the cathode of the second diode D2 is connect with the output end of the flyback transformer T1, described
The second end of second resistance R2 is connect with the first end of the second capacitor C2, the first end of the second resistance R2 and described the
Between the second end parallel connection of two capacitor C2 and the positive electrode and negative electrode of the second diode D2.
The over-voltage adjustment circuit 140 includes third diode D3, the 4th resistance R4, the 5th resistance R5 and the 4th capacitor
C4；The output end of the over-voltage adjustment circuit 140 and the input terminal of adjuster connect, the output end and optical coupling of the adjuster
One end of device connects, and the other end of the photo-coupler is connect with the feedback end of the single- stage PFC control circuit, the over-voltage tune
Whole circuit 140 is used to export the voltage of first LED light group detected, and by the Voltage Feedback of first LED light group
To adjuster, the voltage of first LED light group is converted into electric current by the photo-coupler by the adjuster, and will be described
Current feedback gives the feedback end of the single- stage PFC control circuit.
Specifically, (the first LED light group may include LED1 ... LED1n through over-voltage adjustment circuit 140 to the first LED light group
1 foot for feeding back to TL431 adjuster U16, then controls the size of current by optocoupler, feeds back to primary side, and then control single-stage
4 feet of PFC control circuit U1 finally control the base of output by adjusting the working frequency and duty ratio of reference voltage circuit 170
Quasi- voltage.When the first LED light group overtension, the high voltage that over-voltage adjustment circuit 140 measures, by feeding back as described above
To 1 foot of single- stage PFC control circuit U1, and then the voltage for controlling flyback transformer T1 output reduces, so that output electric current is whole
It is constant.
Further, matrix current adjustment circuit 150 includes amplifier tube Q2, operational amplifier U2, RC filter circuit and sampling electricity
R7 is hindered, the first LED light group is concatenated with amplifier tube Q2 and sampling resistor R7.
Sampling resistor R7 is flowed through by the electric current of the first LED light group, the small voltage that sampling resistor R7 is sampled is fed back to
The reference voltage 0.5V of operational amplifier U2 carries out differential comparison, output control amplifier tube Q2, amplification after operational amplifier U2
Pipe Q2 work adjusts amplifier tube Q2c-e pole tension in linear zone, so that the electric current precision by the first LED light group is constant.
For example, it is assumed that the rated current 100mA of LED light group demand, when the ripple current crest value for flowing through LED light group is bigger than normal
When, sampling resistor R7 is 5 ohm, and the voltage crest value bigger than normal sampled is 0.55V, then LED light group is 110mA by electric current,
The reference voltage 0.5V for feeding back to operational amplifier U2 carries out differential comparison, and the 0.05V voltage of deviation is after operational amplifier U2
Output control amplifier tube Q2, so that the c-e pole tension of amplifier tube Q2 increases, so that the ripple voltage crest value of LED light group reduces,
Become 0.5V, then LED light group electric current is adjusted to 100mA；When the ripple current valley value for flowing through LED light group is less than normal, sampling electricity
The peak voltage value less than normal that resistance R7 is sampled is 0.45V, then LED light group is 90mA by electric current, feeds back to operational amplifier U2
Reference voltage 0.5V carry out differential comparison, the 0.05V voltage of deviation export after operational amplifier U2 controls amplifier tube Q2, make
The c-e pole tension for obtaining amplifier tube Q2 reduces, so that the ripple voltage valley value of LED light group increases, becomes 0.5V, then LED light group
Electric current is adjusted to 100mA.To sum up, the ripple voltage peak-to-peak value (i.e. Wave crest and wave trough value) at LED light group both ends reduces, i.e., constant
0.5V, then LED light group electric current is adjusted to constant 100mA, thereby reduces the current ripples for flowing through LED light group, i.e., constant
100mA。
It is grounded after current sampling resistor R7 in first LED light group series current adjustment circuit 150, then connects second from ground
The cathode of the anode of LED light group, the second LED light group is followed by rectifier diode D2 by filter capacitor C3, then is back to transformer,
Form loop.A matrix current adjustment circuit is eliminated in this way, and an over-voltage adjustment circuit reduces filter capacitor quantity, reduces
The loss of LED light group constant-current circuit, the power-efficient improved, while tandem connection type makes the pressure difference of LED light group
It can be worked normally very big, a variety of screen bodies of matching can be facilitated, reduce line cost.
When pwm signal is high level, higher stable reference voltage 0.5V is conveyed to fortune by reference voltage circuit 170
Amplifier U2 is calculated as reference voltage, the voltage sampled at this time by sampling resistor R7 can using reference voltage 0.5V as referring to,
Make operational amplifier U2 output control adjustment amplifier tube Q2, so that increased by the electric current of the second LED light group, then sampling resistor R7
The voltage of sampling is increased to reference voltage, and the brightness of last LED light group brightens；When pwm signal is low level, reference voltage electricity
Road 170 generates lower stable reference voltage 0V and is conveyed to operational amplifier U2 as reference voltage.Pass through sampling electricity at this time
The voltage for hindering R7 sampling can make operational amplifier U2 output control adjustment amplifier tube Q2 using reference voltage 0V as reference, so that
Become smaller by the electric current of LED light group, then down to reference voltage, the brightness of last LED light group is dimmed for the voltage drop of sampling resistor R7.
When linearity light adjusting to be used, when the duty ratio of pwm signal high level becomes larger, reference voltage circuit 170 is produced
The raw reference voltage 0-0.5V become larger, is conveyed to operational amplifier U2 as reference voltage.Pass through sampling resistor R7 at this time
The voltage of sampling can make operational amplifier U2 output control adjustment amplifier tube Q2, so that passing through LED using reference voltage as reference
The electric current of lamp group increases, then the voltage of sampling resistor R7 is increased to reference voltage, and the brightness of last LED light group gradually brightens；Together
Should the duty ratio of pwm signal high level when becoming smaller, the brightness of LED light group is dimmed.
Further, the enable signal for being input to power supply circuit 180 is backlight EN enable signal, when backlight EN enable signal
When for low level, power supply circuit 180 stops providing operating voltage for single- stage PFC control circuit U1, so that single- stage PFC control circuit
U1 stops working, and controls flyback transformer T1 and stop oscillation, and constant-current control circuit stops working, the obstructed overcurrent of LED light group,
LED light group is in OFF state, and single- stage PFC control circuit U1 stops working, and output constant current control circuit also stops working, drop
Low stand-by power consumption.
Flyback transformer T1 output passes through ZCD2 circuit, i.e. R8 and R9, sampled to be followed by single- stage PFC control circuit U1, is
Single- stage PFC control circuit U1 manages LED constant current module and provides zero passage detection signal, so that improving the single- stage PFC control of constant current output
The power factor (PF) of circuit U 1 processed.
Further, the working principle of the overcurrent of the backlight output in constant-current control circuit and overvoltage crowbar 190, electricity
Stream sample resistance R10 sampling is followed by 7 feet of single- stage PFC control circuit U1, when output power is excessive, in the electricity of R10 sampling
Pressure can be greater than the internal reference voltage of 7 feet of single- stage PFC control circuit U1, make single- stage PFC control circuit U1 overload protection and stop
Only work.The VCC voltage that overcurrent and overvoltage crowbar 190 export, it is primary when the overtension of flyback transformer T1 output
Side auxiliary winding similarly also will increase, and 2 feet of single- stage PFC control circuit U1 are detected by the overcurrent and overvoltage crowbar 190
The voltage of VCC makes the voltage of auxiliary winding be limited in safe range, avoids the voltage for making output excessive and damages LED light group.
Further, when PWM to be used is dimmed, reference voltage circuit 170 generates higher stable reference voltage
0.5V is conveyed to operational amplifier U2 as reference voltage.The voltage sampled at this time by sampling resistor R7 can be with reference voltage
0.5V makes operational amplifier U2 output control adjustment amplifier tube Q2, so that the electric current by LED light group increases, then as reference
The voltage of sampling resistor R7 is increased to reference voltage, and the brightness of last LED light group brightens；When pwm signal is low level, benchmark
Potential circuit 170 generates lower stable reference voltage 0V and is conveyed to operational amplifier U2 as reference voltage.Pass through at this time
The voltage of sampling resistor R7 sampling can make operational amplifier U2 output control adjustment amplifier tube using reference voltage 0V as reference
Q2, so that the electric current by LED light group becomes smaller, then the voltage drop of sampling resistor R7 is down to reference voltage, last LED light group it is bright
It spends dimmed；Frequency set by PWM is 100-200Hz, and because of the visual effect of human eye, LED light group work is being always on state.
The technical solution of the embodiment of the present invention is controlled using single- stage PFC control circuit and is exported when whole set of television works, and is saved
High-voltage electrolytic capacitor is removed, power factor (PF) is improved, the voltage symmetry or asymmetric constant current demand of LED backlight lamp group is provided, is reduced
The ripple current of LED backlight lamp group improves the stability of LED backlight lamp group work, reduces constant current line loss, improve electricity
Source efficiency reduces system cost.
The embodiment of the invention also provides a kind of television set, which includes such as any embodiment of embodiment of the present invention institute
The constant-current control circuit stated.
A kind of television set provided in an embodiment of the present invention, is connected to power supply by the input terminal of ON-OFF control circuit, switch
The output end of control circuit is connect with the anode of the first LED light group, the controlled end and single- stage PFC control circuit of ON-OFF control circuit
Output end connection, the cathode of the first LED light group connect with matrix current adjustment circuit, the sampling end of over-voltage adjustment circuit 140 and the
The connection of one LED light group, the output end of over-voltage adjustment circuit are connect with the feedback end of single- stage PFC control circuit, the second LED light group
Anode is connect with matrix current adjustment circuit, and the cathode of the second LED light group is connect with ON-OFF control circuit.ON-OFF control circuit is used for will
It is powered after the output voltage filtering of ON-OFF control circuit to the first LED light group；It is also used to receive the output of the second LED light group
Electric current is simultaneously back to ON-OFF control circuit；Matrix current adjustment circuit is used for the 2nd LED of current control exported according to the first LED light group
The input current of lamp group.Such method optimizes the connection type of constant-current control circuit, and realizing reduces line cost, reduces permanent
The loss of stream improves power-efficient, meanwhile, reduce the ripple current of backlight, improve the stability of backlight work, can
Demand with any number of channels of backlight.
Note that the above is only a better embodiment of the present invention and the applied technical principle.It will be appreciated by those skilled in the art that
The invention is not limited to the specific embodiments described herein, be able to carry out for a person skilled in the art it is various it is apparent variation,
It readjusts and substitutes without departing from protection scope of the present invention.Therefore, although being carried out by above embodiments to the present invention
It is described in further detail, but the present invention is not limited to the above embodiments only, without departing from the inventive concept, also
It may include more other equivalent embodiments, and the scope of the invention is determined by the scope of the appended claims.
Claims (10)
1. a kind of constant-current control circuit, which is characterized in that the constant-current control circuit includes single- stage PFC control circuit, switch control
Circuit, the first LED light group, over-voltage adjustment circuit, matrix current adjustment circuit and the second LED light group processed；The ON-OFF control circuit
Input terminal connects to power supply, and the output end of the ON-OFF control circuit is connect with the anode of first LED light group, the switch
The controlled end of control circuit is connect with the output end of the single- stage PFC control circuit, the cathode of first LED light group with it is described
Matrix current adjustment circuit connection, the sampling end of the over-voltage adjustment circuit are connect with first LED light group, the over-voltage adjustment electricity
The output end on road is connect with the feedback end of the single- stage PFC control circuit, anode and the electric current tune of second LED light group
The cathode of whole circuit connection, second LED light group is connect with the ON-OFF control circuit；
The ON-OFF control circuit, for giving first LED light group after the output voltage filtering by the ON-OFF control circuit
It is powered；It is also used to receive the electric current of the second LED light group output and is back to the ON-OFF control circuit；
The matrix current adjustment circuit, the second LED light group described in the current control for being exported according to first LED light group it is defeated
Enter electric current.
2. constant-current control circuit according to claim 1, which is characterized in that the ON-OFF control circuit includes Half bridge rectifier
Circuit and flyback transformer；The Half bridge rectifier circuit include first diode, the second diode, first capacitor, the second capacitor,
Third capacitor, first resistor and second resistance；The anode of the first diode is connect with the output end of the flyback transformer,
For receiving the voltage of the flyback transformer output, the first end company of the cathode of the first diode and the third capacitor
Connect, the second end of the first resistor is connect with the first end of the first capacitor, the first end of the first resistor with it is described
Between the second end parallel connection of first capacitor and the positive electrode and negative electrode of the first diode, the anode of second diode and institute
The second end of the cathode and the third capacitor of stating the second LED light group is connected, for receiving the cathode of second LED light group
By the electric current of the third capacitor filtering, the cathode of second diode is connect with the output end of the flyback transformer,
The second end of the second resistance is connect with the first end of second capacitor, the first end of the second resistance and described second
Between the second end parallel connection of capacitor and the positive electrode and negative electrode of second diode.
3. constant-current control circuit according to claim 1, which is characterized in that the over-voltage adjustment circuit includes the three or two pole
Pipe, the 4th resistance, the 5th resistance and the 4th capacitor；The output end of the over-voltage adjustment circuit and the input terminal of adjuster connect,
The output end of the adjuster and one end of photo-coupler connect, and the other end of the photo-coupler and the single- stage PFC control
The feedback end of circuit connects, and the over-voltage adjustment circuit is used to export the voltage of first LED light group detected, and by institute
The Voltage Feedback of the first LED light group is stated to adjuster, the voltage of first LED light group is passed through the optocoupler by the adjuster
Clutch is converted into electric current, and the current feedback is given to the feedback end of the single- stage PFC control circuit.
4. constant-current control circuit according to claim 1, which is characterized in that the matrix current adjustment circuit include amplifier tube,
Operational amplifier, RC filter circuit and sampling resistor；The input terminal of the amplifier tube and the cathode of first LED light group connect
It connects, the output end of the amplifier tube is connect with the first end of the sampling resistor, the second end of the sampling resistor and described the
The anode connection of two LED light groups, the operational amplifier are in parallel with the RC filter circuit with the amplifier tube and the sampling
Between the first end of resistance.
5. constant-current control circuit according to claim 4, which is characterized in that the constant-current control circuit further includes benchmark electricity
Volt circuit, the output end of the reference voltage circuit are connect with the matrix current adjustment circuit, the input of the reference voltage circuit
End provides reference voltage for receiving pwm signal, Xiang Suoshu matrix current adjustment circuit.
6. constant-current control circuit according to claim 5, which is characterized in that the constant-current control circuit further includes that brightness is flat
Sliding adjustment circuit, the brightness smooth adjustment circuit are connect with the matrix current adjustment circuit；The brightness smooth adjustment circuit pair
The electric current of first LED light group output is sampled, and is converted into voltage signal, by the voltage signal and reference voltage into
Row compares, and the brightness of first LED light group is adjusted according to comparison result.
7. constant-current control circuit according to claim 1, which is characterized in that the constant-current control circuit further includes EMI filter
Wave circuit and power supply circuit, the output end of the EMI filter circuit is connect with the input terminal of the ON-OFF control circuit, described
The input terminal access of EMI filter circuit connects to power supply, the output end of the power supply circuit and the single- stage PFC control circuit
Power end is connected.
8. constant-current control circuit according to claim 1, which is characterized in that the cathode of first LED light group with it is described
The first end of matrix current adjustment circuit connects, the second end ground connection of the matrix current adjustment circuit, the anode of second LED light group with
The second end ground terminal of the matrix current adjustment circuit connects.
9. constant-current control circuit according to claim 1, which is characterized in that first LED light group includes multiple series connection
LED light, second LED light group includes multiple concatenated LED light.
10. a kind of television set, which is characterized in that including such as described in any item constant-current control circuits of claim 1-9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110767152A (en) * | 2019-11-08 | 2020-02-07 | 深圳市德普微电子有限公司 | Constant current source generating method of LED display screen driving chip |
| CN110971850A (en) * | 2019-12-05 | 2020-04-07 | 深圳创维－Rgb电子有限公司 | Constant-voltage constant-current switching power supply and television |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130057163A1 (en) * | 2011-08-19 | 2013-03-07 | Sehat Sutardja | Regulator for led lighting color mixing |
| US20140265889A1 (en) * | 2013-03-15 | 2014-09-18 | Lumenetix, Inc. | Cascade led driver and control methods |
| CN205105105U (en) * | 2015-11-12 | 2016-03-23 | 苏州汇川技术有限公司 | Miniwatt auxiliary electrical power source |
| CN206775772U (en) * | 2017-03-29 | 2017-12-19 | 宾海文 | Linear full voltage LED drive circuit |
| CN107959991A (en) * | 2017-10-23 | 2018-04-24 | 东莞达文西光电有限公司 | A kind of dimming driving circuit |
| CN109362157A (en) * | 2018-12-04 | 2019-02-19 | 深圳创维－Rgb电子有限公司 | Constant current control circuit and TV |
-
2019
- 2019-03-28 CN CN201910245559.3A patent/CN109862292B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130057163A1 (en) * | 2011-08-19 | 2013-03-07 | Sehat Sutardja | Regulator for led lighting color mixing |
| US20140265889A1 (en) * | 2013-03-15 | 2014-09-18 | Lumenetix, Inc. | Cascade led driver and control methods |
| CN205105105U (en) * | 2015-11-12 | 2016-03-23 | 苏州汇川技术有限公司 | Miniwatt auxiliary electrical power source |
| CN206775772U (en) * | 2017-03-29 | 2017-12-19 | 宾海文 | Linear full voltage LED drive circuit |
| CN107959991A (en) * | 2017-10-23 | 2018-04-24 | 东莞达文西光电有限公司 | A kind of dimming driving circuit |
| CN109362157A (en) * | 2018-12-04 | 2019-02-19 | 深圳创维－Rgb电子有限公司 | Constant current control circuit and TV |
Non-Patent Citations (1)
| Title |
|---|
| 刘广学: "LED电视大尺寸多灯条高效背光驱动和电源一体化技术的设计与实现", 《中国优秀硕士学位论文全文数据库》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110767152A (en) * | 2019-11-08 | 2020-02-07 | 深圳市德普微电子有限公司 | Constant current source generating method of LED display screen driving chip |
| CN110971850A (en) * | 2019-12-05 | 2020-04-07 | 深圳创维－Rgb电子有限公司 | Constant-voltage constant-current switching power supply and television |
| CN110971850B (en) * | 2019-12-05 | 2022-05-03 | 深圳创维－Rgb电子有限公司 | A constant voltage and constant current switching power supply and TV |
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|---|---|
| CN109862292B (en) | 2021-08-03 |
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