CN205071381U - LED driving circuit - Google Patents

Abstract

The embodiment of the utility model relates to a LED driving circuit. This LED driving circuit includes: the input, power converter, output, control circuit, including control chip, control chip includes the feeder ear of coupling to input, control chip comes the control power converter according to the power supply change of feeder ear, supply circuit, the coupling is between input and control chip's feeder ear, and the return circuit of discharging, dispose to the feeding end connection with control chip for, input power releases the power supply of feeder ear when changing, with resetting control chip. This kind of LED driving circuit can utilize same control chip to realize dimming function and dimming function not to attached less circuit component, the circuit is simple, easy realization, and with low costs, the practicality is strong.

Description

LED drive circuit

Technical field

Embodiment of the present utility model relates to lighting field, and relates more specifically to light-emitting diode (LED) drive circuit.

Background technology

In the last few years, along with the development of solid-state illumination, Dimmable LED light fixture becomes and becomes more and more popular, and they can meet various different illumination needs.Existing LED application needs to carry out light modulation to LED lamp usually, and such as, the BF1005A3 of BYD Microtronic A/S is a kind of brightness adjustment control integrated circuit (IC) chip, and it has three grades of dimming functions, and easily can be implemented by switch on wall.Concrete grammar is: this integrated circuit (IC) chip can by detecting the changed power of feeder ear, and this power conversion caused by the switch motion of switch on wall, and this integrated circuit (IC) chip carries out light modulation according to this changed power.But this chip must comprise dimming function, if need to realize not dimming function, then need to change control chip.Changing IC chip is a kind of very large adjustment, may bring higher cost, more complicated product line.Therefore, it may be necessary and peripheral circuit is modified, thus utilize same control chip to realize not dimming function.

Utility model content

In view of the above-mentioned shortcoming of prior art, embodiment of the present utility model aims to provide a kind of LED drive circuit that can overcome above-mentioned shortcoming.

Embodiment of the present utility model provides a kind of LED drive circuit, comprising:

-input;

-power inverter;

-export;

-control circuit, comprises control chip, and described control chip comprises the feeder ear being coupled to described input, and described control chip controls described power inverter according to the Electrical change that supplies of described feeder ear;

-power supply circuits, between the feeder ear being coupling in described input and described control chip;

-discharge loop, is configured to be connected with the feeder ear of described control chip, for discharging, the power supply of described feeder ear to reset described control chip when input power changes.

The advantage of this embodiment is, when input power change, such as due to the switch motion of switch on wall cause the changed power of feeder ear time, the power supply of feeder ear can discharge by discharge loop, make control chip merely dead electricity and closing, achieve merely switching function and being shielded by the dimming function of chip.Thus, same set of topological structure can be used in production, and by optionally cutting off or do not cut off discharge loop, just can produce the drive circuit that there is dimming function or not there is dimming function, save the cost of product line.

According to some embodiments, described discharge loop comprises: be connected in the capacitor between ground connection and described feeder ear and the first resistor in parallel, described first resistor is configured to the power supply release stored by described capacitor when described input disconnects, to reset described control chip.

According to some embodiments, described discharge loop also comprises the second resistor be connected with described first resistor in series, and described second resistor can by dismounting.

According to some embodiments, described power inverter comprises inverse excitation type converter, and described inverse excitation type converter comprises former limit winding, vice-side winding and auxiliary winding, described auxiliary winding is coupled to the feeder ear of described control chip via linear regulator, power to carry out voltage stabilizing to described control chip.

According to some embodiments, described input also comprises rectification circuit.

According to some embodiments, described input also comprises filter circuit.

According to some embodiments, described input also comprises circuit of power factor correction.

According to some embodiments, the winding two ends, former limit of described inverse excitation type converter are connected with clamp circuit.

Same control chip can be utilized to realize dimming function and not dimming function according to the LED control circuit of embodiment of the present utility model, and addition of less circuit components, circuit is simple, easily realizes, therefore, there is the advantages such as cost is low, practical.

Accompanying drawing explanation

Accompanying drawing described herein is used to provide further understanding of the present utility model, and form a application's part, schematic description and description of the present utility model, for explaining the utility model, does not form improper restriction of the present utility model, wherein:

Fig. 1 is the circuit diagram of the LED drive circuit schematically shown according to prior art;

Fig. 2 is the working timing figure of the LED drive circuit schematically showing Fig. 1;

Fig. 3 is the block diagram of the LED drive circuit schematically shown according to embodiment of the present utility model;

Fig. 4 is the circuit diagram of the LED drive circuit schematically shown according to embodiment of the present utility model; And

Fig. 5 is the circuit diagram of another LED drive circuit schematically shown according to embodiment of the present utility model.

Embodiment

Some illustrative embodiments below with reference to the accompanying drawings describe principle of the present utility model and spirit.Should be appreciated that describing these execution modes is only used to enable those skilled in the art understand better and then realize the utility model, and not limit scope of the present utility model by any way.

In order to be illustrated more clearly in principle of the present utility model, introduce the LED drive circuit according to prior art simply below in conjunction with Fig. 1 and Fig. 2.Fig. 1 is the circuit diagram of the LED drive circuit schematically shown according to prior art.As shown in Figure 1, diode D1-D4 forms rectifier bridge, carries out rectification to AC input (such as, AC civil power), and then acquisition inputs through rectification AC.Inductor L1 and capacitor C1, C2 form pi type filter, carry out filtering to through rectification AC input.Be supplied to the feeder ear VDD of control chip by resistor R2 and R3 through the voltage of filtering.In addition, the voltage through filtering can also carry out voltage transformation by inverse excitation type converter, and then provides output.Inverse excitation type converter comprises former limit winding, vice-side winding and auxiliary winding.As shown in Figure 1, the two ends of former limit winding are labeled as 1 and 4 respectively, and the two ends of vice-side winding are labeled as 5 and 6 respectively, and the two ends of auxiliary winding are labeled as 2 and 3 respectively.Winding two ends, former limit are connected with clamp circuit, and this clamp circuit is the RCD clamp circuit be made up of capacitor C5, resistor R11 and diode D5.Due to leakage inductance impact, will cause due to voltage spikes when the switching tube M1 of inverse excitation type converter turns off, clamp circuit may be used for suppressing it.Vice-side winding, diode D7, capacitor C4 and resistor R10 etc. form output circuit, provide power output by output node V+ and V-.One or more LED can be connected between output node V+ and V-, one or more LED is powered.

Control chip is the BF1005 chip that BYD Microtronic A/S produces.BF1005A3 in BF1005 series is the high-performance AC/DC switching regulator LED driver with three grades of dimming functions.It uses former frontier inspection to survey (that is, auxiliary winding is on former limit), and does not need secondary side feedback circuit, does not namely need the feedback circuit at vice-side winding place.Secondary detects and usually uses optical coupler, and make circuit more complicated, cost is higher.

When circuit normal running, auxiliary winding, diode D6, resistor R4 and R5 and capacitor C3 can provide supply power voltage by the feeder ear VDD being operating as control chip BF1005 of inverse excitation type converter.Resistor R4 and R5 can also via pressure feedback port Vsense for control chip BF1005 provides Voltage Feedback, and resistor R6 and R9 can via current feedback terminal Isense for control chip 1005 provides current feedback.Control chip is coupled to the grid of switching tube M1 via output OUT, thus exports control signal, for the break-make of control switch pipe M1 to the switching tube M1 of inverse excitation type converter.

As shown in Figure 2, when first time energising (that is, connecting input), R2, R3 will charge to C3, and when the voltage rise at VDD place, the register in BF1005 chip resets and output logic is initialised.Then, circuit enters normal mode of operation, and output OUT will export control signal to switching tube M1, output current will be adjusted to 100% (that is, first stage).If now power-off (namely, user operation switch on wall and by input disconnect), and power-off time is less than 0.8 second, then VDD can remain on Voff, if be now again energized (not only user but also closed by switch on wall), then output logic will become second stage, and output current will become 40% (that is, second stage).Similarly, if be again energized within the retention time (0.8 second), then can enter the phase III, output circuit becomes such as 20%.Similarly, the more next stage be zero by drive circuit output current, namely turn off the light.Then, this circulation can be sustained.If power-off time was more than 5 seconds, VDD falls under Voff, then circuit can reset, and will forward the first stage to.

More detailed introduction about BF1005 chip and peripheral circuit configuration thereof can with reference to the product data sheet of BYD Microtronic A/S, and this tables of data such as can find in following webpage:

http://bydit.com/docc/products/MicroElectronics/2436.html。

Known from the above description, this control chip cannot realize the drive circuit of not dimming function, i.e. the closedown of switch in 0.8 second and reopen and will inevitably cause light modulation, and cannot realize all returning to 100% output at every turn.Therefore, in order to realize the drive circuit of not dimming function, further must design peripheral circuit.Fig. 3 is the block diagram of the LED drive circuit schematically shown according to embodiment of the present utility model.This LED drive circuit comprises: input 110, power inverter 120, output 130, power supply circuits 140 and control chip 150.Input 110 can receive power supply from AC civil power, and comprises switch at input 110 place, such as wall type switch.In addition, input 110 can also comprise electromagnetic interference (EMI) filter, rectifier (such as, bridge rectifier in Fig. 1), filter (pi type filter such as, in Fig. 1) and power factor correction (PFC) circuit.Power inverter 120 can be inverse excitation type converter as shown in Figure 1, and it can comprise three-winding transformer and switching tube etc.Power supply circuits 140 (such as, R2 and R3 in Fig. 1) are coupling between the feeder ear of input 110 and control chip 150, for powering to control chip 150.Control chip 150 comprises the feeder ear being coupled to input 110, and control chip 150 controls power inverter 120 according to feeder ear for Electrical change, and then controls the parameter such as power of output 130.The power supply change case of feeder ear is as caused by turning on and off of the switch of input 110, and the break-make of switch can cause the effect of energising and power-off.The control end of control chip 150 can be coupled to the switching tube (such as, the switching tube M1 in Fig. 1) in power inverter 120, the switching characteristic (such as, switching frequency etc.) of control switch pipe, and then adjustment exports.Such as, as shown in Figure 1, within power-off certain hour, feeder ear voltage still remains on certain level, the control logic of control chip 150 can not be reset, and then realize dimming function by the control logic of control chip 150.

In addition, drive circuit also comprises discharge loop 160, and discharge loop 160 is connected with the feeder ear of control chip 150, for when input power changes, such as during switch OFF, the power supply of feeder ear is discharged, make VDD fall under Voff, to reset control chip 150.Therefore, the dimming function of control chip 150 is removed by discharge loop 160, and then achieves not dimming function.

In order to principle of the present utility model is described further, the circuit diagram below in conjunction with Fig. 4 and Fig. 5 describes in detail.Fig. 4 is the circuit diagram of the LED drive circuit schematically shown according to embodiment of the present utility model.Can find out, as Fig. 1 compares, difference is, is connected to a resistor R24 in addition at the feeder ear VDD place of control chip, and by its ground connection.R24 and C3 constitutes the discharge loop 160 in Fig. 3.When energized, R2, R3 will charge to C3, and in retention time (such as, 0.8 second) after power-off, VDD can remain on Voff.If use resistor R24 to discharge to C3, VDD will be reduced under Voff very soon, thus achieve the drive circuit of not dimming function.The resistance value of resistor R24 should design according to actual conditions, such as, discharge rate can be made enough fast, the voltage drop of VDD be low to moderate under Voff within the retention time by the resistance value adjusting R24.

Fig. 5 schematically shows the circuit diagram of another LED drive circuit according to embodiment of the present utility model.VFB, IFB, DRI end of control chip corresponds respectively to Vsense, Isense and OUT end in Fig. 1 and Fig. 4.As shown in Figure 5, discharge loop comprises resistor R24, R24A and capacitor C8, C8A.The operation principle of discharge loop is substantially the same with the circuit shown in Fig. 4.Resistor R24A is the resistance (that is, resistance value is very little, substantially can be considered zero) of zero resistance.When having installed R24A on circuit, not dimming function can be realized, as shown in Figure 4.When removing R24A, namely discharge loop is disconnected, and can realize dimming function, as shown in Figure 1.Therefore, whether can be realized the switching of two kinds of functions by the installation of resistor R24A, therefore, this design applicability is comparatively strong and cost is lower.As shown in Figure 5, in the circuit that the feeder ear of auxiliary winding to control chip is powered, the feeder ear of control chip is except the DC bus after directly linking pi type filter is to obtain except the electric power needed for initial start, also through the linear regulator including and be made up of switching tube Q2 and Zener diode Z1 etc. and be connected on an auxiliary winding of flyback converter, to obtain the electric power in continuous firing.

In addition, drive circuit can also comprise the circuit of power factor correction (not shown) between the output being connected to pi type filter, for improving electric power efficiency.Drive circuit can also comprise and is connected in the source electrode of switching tube Q1 or M1 and the absorbing circuit of drain electrode place in parallel, for eliminating peak voltage, and then protective circuit element improve EMI.It will be appreciated by those skilled in the art that drive circuit can also comprise the consideration for Electro Magnetic Compatibility (EMC) and electromagnetic interference and the additional circuit that designs, repeat no more herein.In addition, it will be appreciated by those skilled in the art that, when not departing from principle of the present utility model, bridge rectifier shown in the drawings, pi type filter, inverse excitation type converter, switching tube etc. can also present various change.

Claims (8)

1. a LED drive circuit, comprising:

-input (110);

-power inverter (120);

-export (130);

-control circuit, comprise control chip (150), described control chip (150) comprises the feeder ear being coupled to described input (110), and described control chip (150) controls described power inverter (120) according to the Electrical change that supplies of described feeder ear;

-power supply circuits (140), between the feeder ear being coupling in described input (110) and described control chip (150);

It is characterized in that, also comprise:

-discharge loop (160), is configured to be connected with the feeder ear of described control chip (150), for discharging, the power supply of described feeder ear to reset described control chip (150) when input power changes.

2. LED drive circuit according to claim 1, is characterized in that, described discharge loop (160) comprising:

Be connected in the capacitor (C3 between ground connection and described feeder ear in parallel; C8, C8A) and the first resistor (R24), described first resistor (R24) is configured to described capacitor (C3 when described input (110) disconnects; C8, C8A) store power supply release, to reset described control chip (150).

3. LED drive circuit according to claim 2, it is characterized in that, described discharge loop (160) also comprises the second resistor (R24A) be connected in series with described first resistor (R24), and described second resistor (R24A) can by dismounting.

4. LED drive circuit according to claim 1, it is characterized in that, described power inverter (120) comprises inverse excitation type converter, and described inverse excitation type converter comprises former limit winding, vice-side winding and auxiliary winding, described auxiliary winding is coupled to the feeder ear of described control chip (150) via linear regulator, power to carry out voltage stabilizing to described control chip (150).

5. LED drive circuit according to claim 1, is characterized in that, described input (110) also comprises rectification circuit.

6. LED drive circuit according to claim 1, is characterized in that, described input (110) also comprises filter circuit.

7. LED drive circuit according to claim 1, is characterized in that, described input (110) also comprises circuit of power factor correction.

8. LED drive circuit according to claim 4, is characterized in that, the winding two ends, former limit of described inverse excitation type converter are connected with clamp circuit.