CN104270020A - BUCK topology self-adaptation current ripple adjusting circuit inside driving circuit - Google Patents

BUCK topology self-adaptation current ripple adjusting circuit inside driving circuit Download PDF

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Publication number
CN104270020A
CN104270020A CN201410456446.5A CN201410456446A CN104270020A CN 104270020 A CN104270020 A CN 104270020A CN 201410456446 A CN201410456446 A CN 201410456446A CN 104270020 A CN104270020 A CN 104270020A
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China
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circuit
resistance
buck
voltage
pin
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CN201410456446.5A
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Chinese (zh)
Inventor
黄晓东
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康佳集团股份有限公司
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Priority to CN201410456446.5A priority Critical patent/CN104270020A/en
Publication of CN104270020A publication Critical patent/CN104270020A/en

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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current
    • H02M3/33523Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current with galvanic isolation between input and output
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only

Abstract

The invention provides a BUCK topology self-adaptation current ripple adjusting circuit inside a driving circuit. Through arranging an MCU control circuit between an AC-DC topology circuit and the BUCK structure driving circuit, the MCU control circuit detects the duty ratio of driving waveforms of driving voltage of the BUCK structure driving circuit, the AC-DC topology circuit is adjusted to be in a direct current voltage mode provided by the BUCK structure driving circuit according to the numerical value of the duty ratio, in this way, the requirement for the load voltage of the BUCK structure driving circuit is lowered, and it is guaranteed that driving current ripples are not affected by the load voltage within a designed range.

Description

BUCK topology adaptation current ripples Circuit tuning in drive circuit

Technical field

The present invention relates to drive circuit field, particularly relate to a kind of BUCK topology adaptation current ripples Circuit tuning.

Background technology

Adopt BUCK topological circuit to have application as LED backlight drive circuit simple, the advantages such as cost is low, safe and reliable, but the versatility of BUCK topological circuit is poor.Such as, drive the LED string of 50V, the input voltage of BUCK topological circuit is generally good with about 55V, if input voltage is lower, then there will be the problem of driving force deficiency when LED string there are differences; If input voltage is too high, then can there is the larger problem of current ripples.Visible BUCK circuit requires higher to the fluctuation range of input voltage, so BUCK topological circuit exists larger limitation in application.

As shown in Figure 1, BUCK topology current ripples Circuit tuning comprises: the AC-DC topological circuit 11 of FLYBACK structure and BUCK structure LED drive circuit 12 two parts.

Wherein, the AC-DC topological circuit 11 of FLYBACK structure comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1.The elementary tripod pole ground connection of photoelectrical coupler U4, the 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, and this pin plays output negative feedback, controls stable output direct voltage.The negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2.

The LED drive circuit 12 of BUCK structure comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, ISEN pin detects and controls to flow through the size of current of lamp string load, realizes the load of constant current driven LED string.The grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, between the output and the negative pole of driving load of AC-DC topological circuit, be also connected with electric capacity C4;

The ripple of BUCK circuit output current and the relation of input voltage as follows:

Suppose that in Fig. 1, AC-DC output voltage is V1, the voltage being added in inductance L 2 two ends when LED crosstalk pressure is V2, metal-oxide-semiconductor Q2 conducting is Von; The volt microsecond value of inductance L 2 is Et, carries out magnetic balance analysis according to inductance L 2:

The volt microsecond value Et=Von*Ton(1 of inductance L 2 when metal-oxide-semiconductor Q2 conducting)

Inductance L 2 is added in the voltage Von=V1-V2(2 at inductance L 2 two ends when metal-oxide-semiconductor conducting)

Ripple current during inductance L 2 conducting is (3)

By formula 1,2 substitute into formula 3 obtains: (4)

As can be seen from formula 4, the value of (V1-V2) is larger, larger, namely when AC-DC topological circuit output voltage V1 than lamp string pressure V2 large more time, the ripple current of lamp string will increase accordingly.Therefore the output voltage V1 of AC-DC topological circuit is needed automatically to follow LED string load voltage V2, to ensure that the value of (V1-V2) fluctuates in less voltage range, thus ensure that the ripple of the LED drive circuit output current of BUCK structure fluctuates in less scope.

Visible, the LED drive circuit of BUCK structure is comparatively harsh to the requirement of input voltage, need the LED load voltage that fixing DC input voitage collocation is fixing, otherwise the problems such as the not enough or output current ripple of driving force is large will be there is, be alternatively that the LED drive circuit of BUCK structure requires higher to LED string load voltage conversely, make practical application there is larger limitation.

Summary of the invention

For this reason, technical problem to be solved by this invention is: provide the Circuit tuning of the BUCK topology adaptation current ripples in a kind of drive circuit, make BUCK structure drive circuit lower to load voltage requirement, ensure the impact of the ripple of drive current not by load voltage in scope of design.

So, the invention provides the BUCK topology adaptation current ripples Circuit tuning in a kind of drive circuit, comprise: AC-DC topological circuit and BUCK structure drive circuit, AC-DC topological circuit provides direct voltage for BUCK structure drive circuit, MCU control circuit is connected with between AC-DC topological circuit and BUCK structure drive circuit, MCU control circuit for detecting the drive waveforms duty ratio of BUCK structure drive circuit driving voltage, and according to the direct voltage that the numerical value of this duty ratio adjustment AC-DC topological circuit provides for BUCK structure drive circuit.

Wherein, described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the drive waveforms output voltage of BUCK structure drive circuit, other one end of resistance R8 is connected with AC-DC topological circuit, for adjusting the output dc voltage of AC-DC topological circuit.

Described AC-DC topological circuit comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1.The elementary tripod pole ground connection of photoelectrical coupler U4, the 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, and this pin plays output negative feedback, controls stable output direct voltage.The negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2.

The reference pole reference voltage of described linear stable U5 is 2.5V.

Described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the drive waveforms output voltage of BUCK structure drive circuit, and other one end of resistance R8 is connected with the reference pole of AC-DC topological circuit neutral line source of stable pressure U5.

Described BUCK structure drive circuit comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, ISEN pin detects and controls to flow through the size of current of lamp string load, realizes the load of constant current driven LED string.The grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, between the output and the negative pole of driving load of AC-DC topological circuit, be also connected with electric capacity C4;

Described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the DRIVER pin for outputting drive voltage of BUCK chip U2 in BUCK structure drive circuit, other one end of resistance R8 is connected with AC-DC topological circuit, for adjusting the output dc voltage of AC-DC topological circuit.

Described in BUCK topology adaptation current ripples Circuit tuning of the present invention, AC-DC topological circuit comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1.The elementary tripod pole ground connection of photoelectrical coupler U4, the 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, and this pin plays output negative feedback, controls stable output direct voltage.The negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2.

Described BUCK structure drive circuit comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, ISEN pin detects and controls to flow through the size of current of lamp string load, realizes the load of constant current driven LED string.The grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, between the output and the negative pole of driving load of AC-DC topological circuit, be also connected with electric capacity C4;

Described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the DRIVER pin for outputting drive voltage of BUCK chip U2 in BUCK structure drive circuit, and other one end of resistance R8 is connected with the reference pole of AC-DC topological circuit neutral line source of stable pressure U5.

Wherein, the reference pole reference voltage of described linear stable U5 is 2.5V.

When described driving duty ratio is for being more than or equal to 90% and being less than or equal to 95%, the direct voltage that AC-DC topological circuit provides for BUCK structure drive circuit is constant, when described driving duty ratio is for being greater than 95%, AC-DC topological circuit raises its direct voltage provided for BUCK structure drive circuit, when described driving duty ratio is for being less than 90%, AC-DC topological circuit reduces its direct voltage provided for BUCK structure drive circuit.

BUCK topology adaptation current ripples Circuit tuning in drive circuit of the present invention, by arranging a MCU control circuit between AC-DC topological circuit and BUCK structure drive circuit, MCU control circuit is made to detect the drive waveforms duty ratio of BUCK structure drive circuit driving voltage, and according to the direct voltage mode that the numerical value adjustment AC-DC topological circuit of this duty ratio provides for BUCK structure drive circuit, BUCK structure drive circuit is reduced load voltage requirement, ensures the impact of the ripple of drive current not by load voltage in scope of design.

Accompanying drawing explanation

Fig. 1 is BUCK topology current ripples Circuit tuning schematic diagram in prior art;

Fig. 2 is the BUCK topology adaptation current ripples Circuit tuning block diagram in drive circuit described in the embodiment of the present invention;

Fig. 3 is the Voltage Cortrol schematic diagram in the BUCK topology adaptation current ripples Circuit tuning in drive circuit described in the embodiment of the present invention;

Fig. 4 is the BUCK topology adaptation current ripples Circuit tuning schematic diagram in drive circuit described in the embodiment of the present invention.

Embodiment

Below, describe the present invention by reference to the accompanying drawings.

The present embodiment provides the Circuit tuning of the BUCK topology adaptation current ripples in a kind of drive circuit, and this circuit is applicable to the applications such as LED liquid crystal television backlight drive circuit, light-emitting diode display backlight drive circuit, LED illumination drive circuit.

As shown in Figure 2, the BUCK topology adaptation current ripples Circuit tuning in drive circuit, comprising: AC-DC topological circuit 21, BUCK structure drive circuit 22 and MCU control circuit 23.

Wherein, AC-DC topological circuit 21 provides direct voltage for BUCK structure drive circuit 22, MCU control circuit 23 is connected with between AC-DC topological circuit 21 and BUCK structure drive circuit 22, MCU control circuit 23 for detecting the drive waveforms duty ratio of BUCK structure drive circuit 22 driving voltage, and according to the direct voltage that the numerical value of this duty ratio adjustment AC-DC topological circuit 21 provides for BUCK structure drive circuit 22.

MCU control circuit 23 comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the drive waveforms output voltage of BUCK structure drive circuit, other one end of resistance R8 is connected with AC-DC topological circuit, for adjusting the output dc voltage of AC-DC topological circuit.

As shown in Figure 4, the present embodiment with LED string for load is described, described AC-DC topological circuit 21 comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1.The elementary tripod pole ground connection of photoelectrical coupler U4, the 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, and this pin plays output negative feedback, controls stable output direct voltage.The negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2.

Described BUCK structure drive circuit 22 comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, ISEN pin detects and controls to flow through the size of current of lamp string load, realizes the load of constant current driven LED string.The grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, between the output and the negative pole of driving load of AC-DC topological circuit, be also connected with electric capacity C4;

Described MCU control circuit 23 comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the DRIVER pin for outputting drive voltage of BUCK chip U2 in BUCK structure drive circuit, and other one end of resistance R8 is connected with the gate pole of AC-DC topological circuit neutral line source of stable pressure U5.

BUCK topology adaptation current ripples Circuit tuning in drive circuit described in the present embodiment comprises the AC-DC circuit based on FLYBACK topological structure, the LED drive circuit of BUCK topological structure and MCU control circuit three part.Compare prior art scheme and add MCU control circuit part.

1, the AC-DC circuit of FLYBACK topological structure, its function the alternating voltage of civil power is changed into direct voltage output, as the input voltage of BUCK structure LED drive circuit.

2, the LED drive circuit of BUCK topological structure, its function mainly provides constant current for the load of LED string, realizes constant current and drives.The pass of BUCK topological circuit LED string load voltage V2 and direct voltage V1 is: (5),

Wherein D is the duty ratio of the drive waveforms of the DRIVER pin of BUCK chip U2, and when formula can find out that V2 and V1 value difference is larger thus, the value of D is less, therefore can be judged the difference of direct voltage V1 and LED string load voltage V2 by the value detecting D.

3, MCU control circuit, its major function is the drive waveforms by detecting BUCK control chip U2 outputting drive voltage, judge the duty ratio of drive waveforms, control procedure as shown in Figure 3, if the duty ratio of drive waveforms is less than 90%, the analog voltage that MCU control circuit then controls the output of its analog-to-digital conversion AD1 pin raises (being greater than 2.5 V) step by step, the output dc voltage of AC-DC topological circuit is reduced, until the driving duty ratio of BUCK structure drive circuit is greater than 90%.If the duty ratio of drive waveforms is greater than 95%, then the analog voltage that MCU control AD1 pin exports reduces (being less than 2.5V) step by step, and the output dc voltage of AC-DC topological circuit raises, until the driving duty ratio of BUCK structure drive circuit is less than 95%.If the duty ratio of drive waveforms is just between 90% to 95%, comprise 90% and 95%, MCU control circuit then controls the analog voltage that its analog-to-digital conversion AD1 pin exports 2.5V, and the output dc voltage of AC-DC topological circuit is constant.

MCU control circuit realizes AC-DC topological circuit output voltage following LED string load voltage by resistance R8 control AC-DC topological circuit voltage feedback loop, and the voltage feedback loop of AC-DC topological circuit comprises resistance R2, resistance R3, resistance R4, resistance R5, resistance R6, resistance R8, electric capacity C3, photoelectrical coupler U4, linear stable U5.Wherein the reference voltage of linear stable U5 is 2.5V, i.e. V3=2.5V.Physical circuit is analyzed as follows:

Obtained by Kirchhoff's current law (KCL): (6)

??(7)

??(8)

??(9)

Formula 7,8,9 is substituted into formula 6 arrange:

??(10)

As can be seen from formula 10, in formula as long as after resistance R3 and R4 confirms, formula value just secure.And also be fixed value after determining resistance value, therefore the output voltage VAD1 that only need adjust the AD1 pin of MCU just can adjust the output dc voltage V1 of AC-DC.When time, equal 0, AC-DC output dc voltage V1 constant; When time, be greater than 0, AC-DC output dc voltage V1 to increase; When time, be less than 0, AC-DC output dc voltage V1 to reduce.

In sum, Circuits System judges between the output dc voltage V1 of AC-DC topological circuit and LED string load voltage V2 by the driving duty ratio D detecting BUCK circuit voltage difference.If this difference is larger, the ripple of BUCK structure drive circuit output current then can be caused larger, therefore by the voltage feedback loop of MCU control circuit control AC-DC topological circuit, the output voltage V1 of AC-DC topological circuit is made to follow the voltage V2 of LED string load, make the value of (V1-V2) in certain scope, thus ensure that the ripple of the drive current that BUCK structure drive circuit exports under different LED lamp string load voltage is all in certain scope.

BUCK structure drive circuit can be made to reduce the requirement of LED string load voltage by the design of foregoing circuit structure, and can ensure that the ripple of LED string drive current is in scope of design, and can not by the impact of LED string load voltage.

In sum, BUCK topology adaptation current ripples Circuit tuning in drive circuit described in the present embodiment, by arranging a MCU control circuit between AC-DC topological circuit and BUCK structure drive circuit, MCU control circuit is made to detect the drive waveforms duty ratio of BUCK structure drive circuit driving voltage, and according to the direct voltage mode that the numerical value adjustment AC-DC topological circuit of this duty ratio provides for BUCK structure drive circuit, BUCK structure drive circuit is reduced load voltage requirement, ensure the impact of the ripple of drive current not by load voltage in scope of design.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. the BUCK topology adaptation current ripples Circuit tuning in a drive circuit, comprise: AC-DC topological circuit and BUCK structure drive circuit, AC-DC topological circuit provides direct voltage for BUCK structure drive circuit, it is characterized in that, MCU control circuit is connected with between AC-DC topological circuit and BUCK structure drive circuit, MCU control circuit for detecting the drive waveforms duty ratio of BUCK structure drive circuit driving voltage, and according to the direct voltage that the numerical value of this duty ratio adjustment AC-DC topological circuit provides for BUCK structure drive circuit.
2. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 1, it is characterized in that, described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the drive waveforms output voltage of BUCK structure drive circuit, other one end of resistance R8 is connected with AC-DC topological circuit, for adjusting the output dc voltage of AC-DC topological circuit.
3. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 1, it is characterized in that, described AC-DC topological circuit comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1, the elementary tripod ground connection of photoelectrical coupler U4, secondary 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, the negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2.
4. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 3, is characterized in that, the reference pole reference voltage of described linear stable U5 is 2.5V.
5. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 3, it is characterized in that, described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the drive waveforms output voltage of BUCK structure drive circuit, and other one end of resistance R8 is connected with the reference pole of AC-DC topological circuit neutral line source of stable pressure U5.
6. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 1, it is characterized in that, described BUCK structure drive circuit comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, the size of current of ISEN pin senses load and control flow check is overdrived, realize constant current driven load, the grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, electric capacity C4 is also connected with between the output and the negative pole of driving load of AC-DC topological circuit.
7. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 6, it is characterized in that, described MCU control circuit comprises: MCU control chip, the resistance R11 that pin is connected is detected with the duty ratio of MCU control chip, and the resistance R8 to be connected with the analog-to-digital conversion pin of MCU control chip, other one end of resistance R11 is connected with the DRIVER pin for outputting drive voltage of BUCK chip U2 in BUCK structure drive circuit, other one end of resistance R8 is connected with AC-DC topological circuit, for adjusting the output dc voltage of AC-DC topological circuit.
8. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 1, it is characterized in that, described AC-DC topological circuit comprises: for the flyback topologies control chip U1 of control AC-DC voltage transitions, its DRIVER pin for outputting drive voltage is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is by resistance R1 ground connection, the drain electrode of field effect transistor Q1 is connected with primary coil one end of transformer T1, the primary coil other end of T1 is connected with rectification circuit output end, secondary coil one end of transformer T1 is connected with the positive pole of diode D2, the negative pole of diode D2 is connected to BUCK structure drive circuit input, the negative pole of diode D2 is also by electric capacity C2 ground connection, the secondary coil other end ground connection of transformer T1, the elementary tripod pole ground connection of photoelectrical coupler U4, 4th pin of photoelectrical coupler U4 is connected to the FB pin of flyback topologies control chip U1, the negative pole of diode D2 is also connected to photoelectrical coupler U4 level first pin by resistance R2, photoelectrical coupler U4 level crus secunda is connected with the negative electrode of linear stable U5, the plus earth of linear stable U5, the reference pole of linear stable U5 is connected to MCU control circuit, resistance R6 and photoelectrical coupler U4 secondary parallel, photoelectrical coupler U4 level crus secunda that after resistance R5 connects with electric capacity C3, one end of resistance R5 is connected to, one end of electric capacity C3 is by resistance R4 ground connection, other one end of resistance R4 is also connected with resistance R3, other one end of resistance R3 is connected to the negative pole of diode D2,
Described BUCK structure drive circuit comprises: drive load, the positive pole of load is driven to be connected with the output of AC-DC topological circuit, the negative pole of load is driven to be connected to the drain electrode of field effect transistor Q2 by coil L2, the source electrode of field effect transistor Q2 is by resistance R7 ground connection, the source electrode of field effect transistor Q2 is also connected with the ISEN pin of BUCK chip U2, ISEN pin senses also controls the size of current flowing through the load of lamp string, realize constant current driven load, the grid of field effect transistor Q2 is connected to the DRIVER pin for outputting drive voltage of BUCK chip U2, the drain electrode of field effect transistor Q2 is also connected with the positive pole of diode D3, the negative pole of diode D3 is connected to the output of AC-DC topological circuit, electric capacity C4 is also connected with between the output and the negative pole of driving load of AC-DC topological circuit,
Described MCU control circuit comprises: MCU control chip, detect the resistance R11 that pin is connected and the resistance R8 be connected with the analog-to-digital conversion pin of MCU control chip with the duty ratio of MCU control chip, other one end of resistance R11 is connected with the DRIVER pin for outputting drive voltage of BUCK chip U2 in BUCK structure drive circuit, and other one end of resistance R8 is connected with the reference pole of AC-DC topological circuit neutral line source of stable pressure U5.
9. the BUCK topology adaptation current ripples Circuit tuning in drive circuit according to claim 8, is characterized in that, the reference pole reference voltage of described linear stable U5 is 2.5V.
10. the BUCK topology adaptation current ripples Circuit tuning in the drive circuit according to claim 1 to 9 any one, it is characterized in that, when described driving duty ratio is for being more than or equal to 90% and being less than or equal to 95%, the direct voltage that AC-DC topological circuit provides for BUCK structure drive circuit is constant, when described driving duty ratio is for being greater than 95%, AC-DC topological circuit raises its direct voltage provided for BUCK structure drive circuit, when described driving duty ratio is for being less than 90%, AC-DC topological circuit reduces its direct voltage provided for BUCK structure drive circuit.
CN201410456446.5A 2014-09-10 2014-09-10 BUCK topology self-adaptation current ripple adjusting circuit inside driving circuit CN104270020A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104540306A (en) * 2015-01-22 2015-04-22 英飞特电子(杭州)股份有限公司 LED driver
CN106026718A (en) * 2015-03-30 2016-10-12 英飞凌科技奥地利有限公司 System and Method for a Switched-Mode Power Supply

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201199743Y (en) * 2008-05-19 2009-02-25 大焱电机有限公司 Lamp string control circuit
CN102176797A (en) * 2010-12-06 2011-09-07 周宇超 Merged illumination and emergent light-emitting diode (LED) fluorescent lamp
CN102237792A (en) * 2010-04-30 2011-11-09 美芯晟科技(北京)有限公司 Voltage compensation circuit for constant-current system
CN102420535A (en) * 2010-12-13 2012-04-18 成都成电硅海科技股份有限公司 Switching type multi-power management circuit with extremely low power consumption
CN102448223A (en) * 2010-08-24 2012-05-09 卡西欧计算机株式会社 Semiconductor light source apparatus and semiconductor light source control method
CN203086777U (en) * 2011-11-08 2013-07-24 爱特梅尔公司 Circuit for color correcting device driver, driving illumination element system and driving light-emitting element system
CN103269161A (en) * 2013-05-30 2013-08-28 电子科技大学 Constant-current output BUCK power circuit

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201199743Y (en) * 2008-05-19 2009-02-25 大焱电机有限公司 Lamp string control circuit
CN102237792A (en) * 2010-04-30 2011-11-09 美芯晟科技(北京)有限公司 Voltage compensation circuit for constant-current system
CN102448223A (en) * 2010-08-24 2012-05-09 卡西欧计算机株式会社 Semiconductor light source apparatus and semiconductor light source control method
CN102176797A (en) * 2010-12-06 2011-09-07 周宇超 Merged illumination and emergent light-emitting diode (LED) fluorescent lamp
CN102420535A (en) * 2010-12-13 2012-04-18 成都成电硅海科技股份有限公司 Switching type multi-power management circuit with extremely low power consumption
CN203086777U (en) * 2011-11-08 2013-07-24 爱特梅尔公司 Circuit for color correcting device driver, driving illumination element system and driving light-emitting element system
CN103269161A (en) * 2013-05-30 2013-08-28 电子科技大学 Constant-current output BUCK power circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104540306A (en) * 2015-01-22 2015-04-22 英飞特电子(杭州)股份有限公司 LED driver
CN106026718A (en) * 2015-03-30 2016-10-12 英飞凌科技奥地利有限公司 System and Method for a Switched-Mode Power Supply
US9991791B2 (en) 2015-03-30 2018-06-05 Infineon Technologies Austria Ag System and method for a switched-mode power supply
US10148175B2 (en) 2015-03-30 2018-12-04 Infineon Technologies Austria Ag System and method for a switched-mode power supply

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