CN205005294U

CN205005294U - LED drive circuit of flat tuning light scope

Info

Publication number: CN205005294U
Application number: CN201520231207.XU
Authority: CN
Inventors: 唐荣; 阳宗田
Original assignee: DONGGUAN YINGJU ELECTRONIC Co Ltd
Current assignee: DONGGUAN YINGJU ELECTRONIC Co Ltd
Priority date: 2015-04-17
Filing date: 2015-04-17
Publication date: 2016-01-27
Anticipated expiration: 2025-04-17

Abstract

The utility model provides a LED drive circuit of flat tuning light scope, this circuit include the auxiliary power circuit for constant voltage constant -current regulation circuit power supply, and auxiliary power circuit includes that the first electricity end of getting gets the electricity with the second and hold, the first electricity end of getting is followed get on transformer T1's secondary limit, the second is got the electricity end and is followed get on transformer T1's former limit, when transformer T1's secondary polygonal voltage is less than in the power supply voltage of the chip of constant current constant voltage regulating circuit, auxiliary power circuit gets electricity end through the second and gets the electricity from transformer T1's former limit and get the under voltage problem of electricity end in order to compensate the second, thereby make the constant current constant voltage regulating circuit still can normally to work, keep the dimming function, therefore, even this drive circuit arrives LED adjustting of the lighteness under the very little condition, the normal work that still can keep the dimming function, the scope of adjusting luminance is wide.

Description

The LED drive circuit of wide dimming scope

Technical field

The utility model relates to LED drive circuit field, particularly a kind of LED drive circuit of wide dimming scope.

Background technology

At present, LED has energy-saving and environmental protection, life-span length, light efficiency advantages of higher because of it, is used widely at lighting field.In the popularization and application process of LED illumination, because the stability requirement of LED lamp bead to electric current is higher, therefore the special drive circuit of general needs is driven it, but, the design of LED drive circuit but also exists some crucial problem always to be had: (1) driving power efficiency is not high enough, and power factor is also undesirable; (2) on the high side, drive circuit is complicated, and reliability is low.Controlling driving power instability is the main cause causing LED service life reduction.

For this reason, propose in the industry multiple solution, such as, the article that " modern display " has been delivered be entitled as in October, 2011 (total 129 phases) " the HB_LED driving power design based on _ PFC_LLC_CV_CC_ topological structure " namely discloses the complete machine topology design structure of " the superfine rectification+constant current constant voltage of PFC+ half-bridge logical link control (LLC) resonant+Xiao ", and this structure obtains widespread adoption due to its high reliability and high stability.But in actual applications, carrying out light modulation to LED is a main function, for this reason, is generally that the constant-current constant-voltage circuit of above topology structure is increased dimming function at present, the dim signal that the external world inputs is fed back to LLC circuit by constant-current constant-voltage circuit, thus realizes light modulation.But, there is a serious problem in this circuit: based on considerations such as stability, the chip of constant-current constant-voltage circuit is from the secondary side power taking of the transformer of LLC circuit, but, along with the adjustment of dim signal, when needs by brightness regulation to when being less than certain value (circuit output current will be adjusted to and be less than certain value), the voltage of the secondary side of the transformer of LLC circuit can be less than the starting resistor of the chip of constant-current constant-voltage circuit, constant-current constant-voltage circuit is caused normally to work, dimming function lost efficacy, the dimming scope of the therefore current LED drive circuit based on above topology is smaller.

Summary of the invention

The LED drive circuit that the purpose of this utility model is to avoid above-mentioned weak point of the prior art and provides wide dimming scope.

The purpose of this utility model is achieved through the following technical solutions:

A kind of LED drive circuit of wide dimming scope is provided, comprise the current rectifying and wave filtering circuit connected successively from input to output, pfc circuit, LLC translation circuit and secondary current rectifying and wave filtering circuit, described LLC translation circuit comprises transformer T1, the auxiliary power circuit also comprising constant pressure and flow regulating circuit and power for constant pressure and flow regulating circuit, described constant pressure and flow regulating circuit is sampled from the output of described secondary current rectifying and wave filtering circuit and is combined the outside dim signal inputted and generates, send conditioning signal to described LLC translation circuit, and then regulate the output of described LLC translation circuit, described auxiliary power circuit comprises the first power taking end and the second power taking end, described first power taking end is from the secondary side power taking of described transformer T1, described second power taking end is from the former limit power taking of described transformer T1.

Wherein, the former limit of described transformer T1 is in series with inductance L 5, and described second power taking end is connected with described inductance L 5 with power taking.

Wherein, described pfc circuit comprises pfc controller U2, and described LLC translation circuit comprises LLC controller U1, it is characterized in that: described pfc controller U2 from system power supply end VCC power taking, described LLC controller U1 through delay circuit from system power supply end VCC power taking.

Wherein, also comprise EMC filter circuit, described civil power inputs to a described current rectifying and wave filtering circuit after EMC filter circuit.

Wherein, described pfc circuit also comprises switching tube Q17, energy storage inductor L4, diode D2 and output capacitance C39, the input of described energy storage inductor L4 is connected with pfc circuit input, the output of described energy storage inductor is on the one hand through switching tube Q17 ground connection, the output of pfc circuit is connected on the other hand through diode D2, described output capacitance C39 is connected between the output of pfc circuit and power supply ground, and described switching tube is conduction and cut-off by described pfc controller controls.

Wherein, described pfc controller U2 is L6563 chip.

Wherein, described LLC controller U1 is L6599 chip.

The beneficial effects of the utility model: the utility model provides a kind of LED drive circuit of wide dimming scope, this circuit comprises the auxiliary power circuit of powering for constant pressure and flow regulating circuit, auxiliary power circuit comprises the first power taking end and the second power taking end, described first power taking end is from the secondary side power taking of described transformer T1, described second power taking end is from the former limit power taking of described transformer T1, in drive circuit works process, when the secondary side voltage of transformer T1 is greater than the supply power voltage of the chip of constant current constant voltage regulating circuit, auxiliary power circuit through the first power taking end from the secondary side power taking of transformer T1 for constant current constant voltage regulating circuit is powered, thus reliable and stable power supply is provided, when the secondary side voltage of transformer T1 is less than the supply power voltage in the chip of constant current constant voltage regulating circuit, auxiliary power circuit through the second power taking end from the former limit limit power taking of transformer T1 to make up the undertension problem of the second power taking end, thus constant current constant voltage regulating circuit still can normally be worked, keep dimming function, therefore, even if this drive circuit is when being adjusted to very little by LED luminance, still the normal work of dimming function can be kept, dimming scope is wide.

Accompanying drawing explanation

The utility model is described in further detail to utilize accompanying drawing, but the embodiment in accompanying drawing does not form any restriction of the present utility model, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the following drawings.

Fig. 1 is electrical block diagram of the present utility model.

Fig. 2 is pfc circuit of the present utility model and LLC translation circuit structural representation.

Fig. 3 is delay circuit structural representation of the present utility model.

Fig. 4 is auxiliary power circuit structural representation of the present utility model.

Include in Fig. 1 to Fig. 4:

1---EMC filter circuit, 2---current rectifying and wave filtering circuit, 3---pfc circuit, 31---the first power-supply circuit, 32---the second power-supply circuit, 33---the 3rd power-supply circuit, 4---LLC translation circuit, 5---secondary current rectifying and wave filtering circuit, 6---constant pressure and flow regulating circuit, 7---auxiliary power circuits.

Embodiment

With the following Examples the utility model is further described.

The embodiment of the LED drive circuit of the wide dimming scope of the utility model, as shown in Figure 1 and Figure 4, the EMC filter circuit connected successively from input to output 1, current rectifying and wave filtering circuit 2, pfc circuit 3, LLC translation circuit 4 and a secondary current rectifying and wave filtering circuit 5.

Pfc circuit 3 comprises pfc controller U2, switching tube Q17, energy storage inductor L4, diode D2 and output capacitance C39, the input of described energy storage inductor L4 is connected with pfc circuit 3 input, the output of described energy storage inductor is on the one hand through switching tube Q17 ground connection, the output of pfc circuit 3 is connected on the other hand through diode D2, described output capacitance C39 is connected between the output of pfc circuit 3 and power supply ground, described switching tube is conduction and cut-off by described pfc controller controls, U2 is L6563 chip, described pfc controller U2 is from system power supply end VCC power taking, system power supply end VCC through the first power-supply circuit 31 from the power taking of pfc circuit 3 input, through the second power-supply circuit 32 from energy storage inductor L4 power taking, through the former limit power taking of the 3rd power-supply circuit 33 from transformer T1.

The pfc controller U2 of pfc circuit 3 adopts three road power-supply circuits, because the magnitude of voltage of drive circuit each device in the course of the work constantly changes, the phenomenon of undertension is easily there is separately from certain some power taking, cause pfc controller U2 power-off, the present embodiment adopts the different node power taking of ability three then effectively can avoid the problems referred to above.

Described LLC translation circuit 4 comprises transformer T1 and LLC controller U1, and LLC controller U1 is L6599 chip.LLC controller U1 through delay circuit from system power supply end VCC power taking, delay circuit comprises switching tube Q20, storage capacitor C4 and is also the charging paths of storage capacitor charging from system power supply end VCC power taking, the collector electrode connected system power end VCC of described switching tube Q2O, emitter connects the power end VDD of LLC controller U1, base stage connects the positive pole of storage capacitor C4, be that storage capacitor C4 charges, until the cathode voltage of storage capacitor C4 triggers described switching tube by charging paths when described system power supply end VCC starts power supply.

LLC controller U1 through delay circuit from system power supply end VCC power taking, can avoid causing system power supply end VCC undertension from system power supply end VCC power taking at system start-up phase LLC controller U1 and pfc controller U2 simultaneously, therefore LLC controller U1 and the reciprocal power-off of pfc controller U2/power on can not occur and the situation that causes LED to glimmer.

The drive circuit of the present embodiment also comprises constant pressure and flow regulating circuit 6 and the auxiliary power circuit 7 for constant pressure and flow regulating circuit 6 power supply, described constant pressure and flow regulating circuit 6 is sampled from the output of described secondary current rectifying and wave filtering circuit 5 and is combined the outside dim signal inputted and generates, send conditioning signal to described LLC translation circuit 4, and then regulate the output of described LLC translation circuit 4, described auxiliary power circuit 7 comprises the first power taking end and the second power taking end, described first power taking end is from the secondary side power taking of described transformer T1, described second power taking end is from the former limit power taking of described transformer T1.Concrete, the former limit of described transformer T1 is in series with inductance L 5, and described second power taking end is connected with described inductance L 5 with power taking.

In drive circuit works process, when the secondary side voltage of transformer T1 is greater than the supply power voltage of the chip of constant current constant voltage regulating circuit, auxiliary power circuit 7 through the first power taking end from the secondary side power taking of transformer T1 for constant current constant voltage regulating circuit is powered, thus reliable and stable power supply is provided, when the secondary side voltage of transformer T1 is less than the supply power voltage in the chip of constant current constant voltage regulating circuit, auxiliary power circuit 7 through the second power taking end from the former limit limit power taking of transformer T1 to make up the undertension problem of the second power taking end, thus constant current constant voltage regulating circuit still can normally be worked, keep dimming function, therefore, even if this drive circuit is when being adjusted to very little by LED luminance, still the normal work of dimming function can be kept, dimming scope is wide.

In the present embodiment, secondary current rectifying and wave filtering circuit 5 circuit comprises circuit of synchronous rectification, and circuit of synchronous rectification realizes based on IR11682 chip.The mode of synchronous rectification is adopted to carry out rectification process to the voltage that LLC translation circuit 4 exports, effectively can improve rectification effect, the quality of drive circuit output current is provided, further, IR11682 chip is adopted to realize synchronous rectification, circuit integrity structure is simple, and required electronic device is few, has effectively saved cost.

Finally should be noted that; above embodiment is only in order to illustrate the technical solution of the utility model; but not the restriction to the utility model protection range; although done to explain to the utility model with reference to preferred embodiment; those of ordinary skill in the art is to be understood that; can modify to the technical solution of the utility model or equivalent replacement, and not depart from essence and the scope of technical solutions of the utility model.

Claims

1. the LED drive circuit of wide dimming scope, comprise the current rectifying and wave filtering circuit connected successively from input to output, pfc circuit, LLC translation circuit and secondary current rectifying and wave filtering circuit, described LLC translation circuit comprises transformer T1, it is characterized in that: the auxiliary power circuit also comprising constant pressure and flow regulating circuit and power for constant pressure and flow regulating circuit, described constant pressure and flow regulating circuit is sampled from the output of described secondary current rectifying and wave filtering circuit and is combined the outside dim signal inputted and generates, send conditioning signal to described LLC translation circuit, and then regulate the output of described LLC translation circuit, described auxiliary power circuit comprises the first power taking end and the second power taking end, described first power taking end is from the secondary side power taking of described transformer T1, described second power taking end is from the former limit power taking of described transformer T1.

2. the LED drive circuit of wide dimming scope as claimed in claim 1, is characterized in that: the former limit of described transformer T1 is in series with inductance L 5, and described second power taking end is connected with described inductance L 5 with power taking.

3. the LED drive circuit of wide dimming scope as claimed in claim 1, it is characterized in that: described pfc circuit comprises pfc controller U2, described LLC translation circuit comprises LLC controller U1, it is characterized in that: described pfc controller U2 from system power supply end VCC power taking, described LLC controller U1 through delay circuit from system power supply end VCC power taking.

4. the LED drive circuit of wide dimming scope as claimed in claim 3, is characterized in that: also comprise EMC filter circuit, and civil power inputs to a described current rectifying and wave filtering circuit after EMC filter circuit.

5. the LED drive circuit of wide dimming scope as claimed in claim 1, it is characterized in that: described pfc circuit comprises pfc controller U2, switching tube Q17, energy storage inductor L4, diode D2 and output capacitance C39, the input of described energy storage inductor L4 is connected with pfc circuit input, the output of described energy storage inductor is on the one hand through switching tube Q17 ground connection, the output of pfc circuit is connected on the other hand through diode D2, described output capacitance C39 is connected between the output of pfc circuit and power supply ground, and described switching tube is conduction and cut-off by described pfc controller controls.

6. the LED drive circuit of wide dimming scope as claimed in claim 5, is characterized in that: described pfc controller U2 is L6563 chip.

7. the LED drive circuit of wide dimming scope as claimed in claim 1, it is characterized in that: described LLC translation circuit comprises LLC controller U1, LLC controller U1 is L6599 chip.