The power driving circuit of LED source and light supply apparatus
Technical field
The present invention relates to a kind of power driving circuit, particularly relate to a kind of power driving circuit and light supply apparatus of LED source.
Background technology
Figure 1A is a kind of power driving circuit of existing light-emitting diode.Please refer to Figure 1A, power driving circuit 100 can produce drive current I1 to drive light-emitting diode 120 luminous.Existing power driving circuit 100 comprises rectification circuit 102, current rectifying and wave filtering circuit 104 and drive circuit 106.Rectification circuit 102 can couple civil power AC, and exports DC power supply DC to current rectifying and wave filtering circuit 104.Thus, current rectifying and wave filtering circuit 104 can will provide input voltage vin to drive circuit 106 after DC power supply DC filtering.
Drive circuit 106 comprises switch 112, diode 114 and electric capacity C.The anode tap of diode 114 is coupled to input voltage vin by switch 112, and the cathode terminal of diode 114 is then coupled to the anode tap of light-emitting diode 120 by electric capacity C ground connection.In addition, light-emitting diode 120 is in parallel with electric capacity C.
Figure 1B is then the power driving circuit of another kind of existing light-emitting diode.Please refer to Figure 1B, power driving circuit 140 equally also comprises rectification circuit 102, and it couples civil power AC and provides DC power supply DC.In addition, power circuit 140 also comprises switch 112, diode 114 and inductance L.Wherein, the cathode terminal of diode 114 couples rectification circuit 102 to couple DC power supply DC, and the anode tap of diode 114 is then by switch 112 ground connection.In addition, the anode tap of diode 114 also couples the cathode terminal of light-emitting diode 122.Light-emitting diode 122 is connected with light-emitting diode 120, and wherein the anode tap of light-emitting diode 120 also couples the cathode terminal of diode 114 by inductance L.
When switch 112 conducting, inductance L can storage drive electric current I 1.Relatively, when switch 112 open circuit, can output driving current I1 and drive light-emitting diode 120 and 122 luminous.In this prior art, because inductance L is current element, therefore easily produce electromagnetic interference.In addition, inductance L volume is larger and heavier, thus affects the volume and weight of overall power driving circuit 140.
Summary of the invention
Therefore, an object of the present invention is to provide a kind of power driving circuit of LED source, can external power correction factor circuit, and stable drive current just can be provided to drive LED source.
In addition, another object of the present invention is to provide a kind of light supply apparatus, can have more frivolous volume.
The power driving circuit of a kind of LED source that the embodiment of the present invention provides, is suitable for from output output driving current to drive LED source.The power driving circuit that the present embodiment provides, comprises adjustable constant current source, the first resistance, the second resistance, the first switch, second switch, the 3rd switch, the 4th switch, the first electric capacity and the second electric capacity.Adjustable constant current source produces continuous current.The first end of the first resistance couples adjustable constant current source, and its current potential is floating voltage, and the current potential of the second end of the first resistance is switch control voltage.The first end of the second resistance is coupled to the second end of the first resistance, and the current potential of the second end of the second resistance is reference voltage.The first end of the first switch couples the second end of the second resistance and its second end is coupled to first node, to couple reference voltage.When the voltage of first node is less than switch control voltage, the first switch conduction.The action of second switch and the first switch inverse, and the first end of second switch is coupled to first node, and its second end is then coupled to output.Similarly, the 3rd switch and second switch synchronization action, the first end of the 3rd switch couples the second end of the second resistance, and its second end is coupled to Section Point, and when the voltage of Section Point is less than switch control voltage, the 3rd switch conduction.Relatively, the 4th switch and the first switch synchronization action.Wherein, the first end of the 4th switch is coupled to Section Point, and its second end then couples output.In addition, the first end of the first electric capacity and the second electric capacity all couples floating voltage, and the second end of the two is coupled to first node and Section Point respectively.
A kind of light supply apparatus that the embodiment of the present invention provides, comprise light emitting module, its first end couples floating voltage; Luminous two modules comprise at least one light-emitting diode.In addition, embodiment of the present invention light supply apparatus also comprises adjustable constant current source, the first resistance, the second resistance, the first charge pump circuit and the second charge pump circuit.Adjustable constant current source can produce continuous current.The first end of the first resistance couples continuous current and its current potential is floating voltage, and the current potential of the second end of the first resistance is switch control voltage.The first end of the second resistance is coupled to the second end of the first resistance, and the current potential of the second end of the second resistance is reference voltage.First charge pump circuit and the second charge pump circuit have the output of the second end coupling light emitting module respectively, and have the input coupling reference voltage.Specifically, the first charge pump circuit and the second charge pump circuit can according to reference voltage in turn from output output driving current to light emitting module, to drive light-emitting diode.
In an embodiment of the present invention, above-mentioned first charge pump circuit such as comprises the first switch, second switch and the first electric capacity, the first end of the first switch couples the input of the first charge pump circuit, second end of the first switch is coupled to first node, wherein when the voltage of first node is less than switch control voltage, the first switch conduction; The action of second switch and the first switch inverse, and the first end of second switch is coupled to first node, its second end is then coupled to the output of the first charge pump circuit; The first end of the first electric capacity couples floating voltage, and its second end is then coupled to first node.
In an embodiment of the present invention, above-mentioned second charge pump circuit such as comprises the 3rd switch, the 4th switch and the second electric capacity.The first end of the 3rd switch couples the input of the second charge pump circuit, and the second end of the 3rd switch is coupled to Section Point, wherein when the voltage of Section Point is less than switch control voltage, and the 3rd switch conduction; The action of the 4th switch and the 3rd switch inverse, and the first end of the 4th switch is coupled to Section Point, its second end is then coupled to the output of the second charge pump circuit; The first end of the second electric capacity couples floating voltage, and the second end is then coupled to Section Point.
Because the first switch is synchronous with the 4th switch, and second switch is synchronous with the 3rd switch, and the action of the first switch and second switch anti-phase, therefore the first electric capacity and the second electric capacity can discharge to light-emitting diode in turn, adjustable constant current source can be used simply, when strengthening current value in constant current source, produce larger voltage difference (Vref-V
fG), now can produce larger LED drive current.Thus, the present invention does not just need external power factor correction circuit, thus can alleviate the volume and weight of circuit integrity.
Above-mentioned explanation is only the general introduction of the embodiment of the present invention, in order to technological means of the present invention can be better understood, and can be implemented according to the content of specification, and can become apparent to allow above and other objects of the present invention, feature and advantage, below especially exemplified by preferred embodiment, and coordinate accompanying drawing, be described in detail as follows.
Accompanying drawing explanation
Figure 1A and Figure 1B is the power driving circuit of existing light-emitting diode.
Fig. 2 is the circuit block diagram of a kind of light supply apparatus according to a preferred embodiment of the present invention.
Fig. 3 is the circuit diagram of a kind of power circuit according to a preferred embodiment of the present invention.
Fig. 4 is the circuit diagram of a kind of drive current generation circuit according to a preferred embodiment of the present invention.
Embodiment
For further setting forth the present invention for the technological means reaching predetermined goal of the invention and take and effect, below in conjunction with accompanying drawing and preferred embodiment, to power driving circuit and its embodiment of light supply apparatus, method, step, structure, feature and effect of the LED source proposed according to the embodiment of the present invention, be described in detail as follows.
Fig. 2 is the circuit block diagram of a kind of light supply apparatus according to a preferred embodiment of the present invention.Please refer to Fig. 2, the light supply apparatus 200 that the present embodiment provides comprises power driving circuit 202 and light emitting module 204.Wherein, light emitting module 204 is such as a LED source, and it has at least one (such as one or multiple serial or parallel connection) light-emitting diode 206.In the present embodiment, the anode tap of light-emitting diode 206 is coupled to power driving circuit 202.Thus, power driving circuit 202 just can drive the light-emitting diode 206 in light emitting module 204 luminous by output driving current I1.
Please continue to refer to Fig. 2, power driving circuit 202 at least comprises drive current and produces circuit 216.Drive current produces circuit 216 and couples light emitting module 204, and couples reference voltage Vref.Thus, drive current produces circuit 216 and can drive light emitting module 204, to light light-emitting diode 206 by output driving current I1 according to reference voltage Vref.
In certain embodiments, power driving circuit 202 also comprises bridge rectifier 212 and power circuit 214.Bridge rectifier 212 couples AC power AC, and produces input voltage vin to power circuit 214.Thus, power circuit 214 just can produce reference voltage Vref and produce circuit 216 to drive current according to input voltage vin.
Fig. 3 is the circuit diagram of a kind of power circuit according to a preferred embodiment of the present invention.Please refer to Fig. 3, the power circuit 214 that the present embodiment provides, comprises resistance R1 and R2, and adjustable constant current source 302.Wherein, the first end of the input coupling resistance R1 of adjustable constant current source 302, and its output couples earthing potential GND and couples bridge rectifier 212, to produce continuous current Ic.In addition, the current potential of the first end of resistance R1 is defined as floating voltage V
fG, the current potential of its second end is then the first end being defined as switch control voltage Vsw and being coupled to resistance R2.Second end of resistance R2 then couples drive current and produces circuit 216, and its current potential is then reference voltage Vref.Following relational expression can be obtained from Fig. 3:
Vref-Vsw=Ic×R2
Vsw-V
FG=Ic×R1
Fig. 4 is the circuit diagram of a kind of drive current generation circuit according to a preferred embodiment of the present invention.Please refer to Fig. 4, drive current produces circuit 216 and comprises charge pump circuit 402 and 404, and the action of the two is inverting each other.In addition, the input of charge pump circuit 402,404 couples power circuit 214 jointly to couple reference voltage Vref, and its output couples light emitting module 204 jointly to supply drive current I1 in turn to light emitting module 204.In the present embodiment, the output of charge pump circuit 402 and 404 is coupled to the anode tap of light-emitting diode 204, and the cathode terminal of light-emitting diode 204 is then coupled to floating voltage V
fG.
Please continue to refer to Fig. 4, charge pump circuit 402 comprises switch 412 and 414 and electric capacity C1.Wherein, the first end of switch 412 is coupled to the input of charge pump circuit 402 to couple reference voltage Vref, and the second end of switch 412 then couples first node N1.In addition, the first end also couple nodes N1 of switch 414, the second end then couples the output of charge pump circuit 402.The first end of electric capacity C1 then couples floating voltage V
fG, the second end couple nodes N1.Wherein, the action of switch 412 and the action of switch 414 anti-phase.
Similarly, charge pump circuit 404 comprises switch 416 and 418 and electric capacity C2.The first end of switch 416 and the second end are coupled to input and the node N2 of charge pump circuit 404 respectively.The first end of switch 418 and the second end are then coupled to the output of node N2 and charge pump circuit 404 respectively.In addition, the first end of electric capacity C2 couples floating voltage V
fG, its second end is then coupled to node N2.Wherein, the action of switch 416 is synchronous with switch 414, and the action of switch 418 is then synchronous with switch 412.
Please continue in the lump with reference to figure 3 and Fig. 4, when the current potential of the voltage V LED1 of node N1 is less than switch control voltage Vsw, switch 412 meeting conducting, switch 414 then open circuit.Now, reference voltage Vref can be charged to electric capacity C1.On the other hand, because switch 416 and 414 is synchronous, and switch 418 and switch 412 are synchronously, therefore switch 416 open circuits, and switch 418 conducting.Now, electric capacity C2 can follow the path electric discharge of switch 418.Therefore, charge pump circuit 404 will from output output driving current I1 to light emitting module 204, to drive light-emitting diode 206 luminous.
Relatively, when the current potential of the voltage V LED2 of node N2 is less than switch control voltage Vsw, switch 416 meeting conducting, and switch 418 can open circuit.In addition, switch 412 also can open circuit synchronous with switch 418, and switch 414 then can conducting synchronous with switch 416.Now, electric capacity C1 can follow the path electric discharge of switch 414.Now, charge pump circuit 402 will from output output driving current I1 to light emitting module 204.On the other hand, reference voltage Vref then can be charged to electric capacity C2.As known from the above, charge pump circuit 402 and 404 can in turn to light emitting module 204 output driving current I1.
In sum, the present invention has following advantage at least:
1. the embodiment of the present invention does not use inductance to be used as energy-storage travelling wave tube, does not therefore have the problem of electromagnetic interference.
2., due to embodiment of the present invention configuration at least two charge pump circuits, it when the voltage stored by electric capacity is lower than compliance voltage level, can be supplied drive current and drives light-emitting diode, can change reference voltage Vref and floating voltage V in turn
fGvoltage difference, change drive current, make electric current and input voltage proportional.Therefore, the present invention does not need to couple power correction factor circuit in addition.
3. due in charge pump circuit, electric capacity wherein one end couple be floating voltage but not earthed voltage, and this floating voltage is associated with reference voltage, and therefore drive current also can not by the impact of reference voltage drift.
4. in this circuit arrangement, owing to not producing the large inductance in magnetic field, so powerful electromagnetic wave can not be produced.
5. power consumed in a power, be only the power that current flowing resistance R1 and R2 consumes, therefore power loss of the present invention is very low.
The above, it is only preferred embodiment of the present invention, not any pro forma restriction is done to the present invention, although the present invention discloses as above with preferred embodiment, but and be not used to limit the present invention, any those skilled in the art, do not departing within the scope of technical solution of the present invention, make a little change when the technology contents of above-mentioned announcement can be utilized or be modified to the Equivalent embodiments of equivalent variations, in every case be do not depart from technical solution of the present invention content, according to any simple modification that technical spirit of the present invention is done above embodiment, equivalent variations and modification, all still belong in the scope of technical solution of the present invention.