CN203313482U - LED drive circuit - Google Patents
LED drive circuit Download PDFInfo
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- CN203313482U CN203313482U CN2013203004128U CN201320300412U CN203313482U CN 203313482 U CN203313482 U CN 203313482U CN 2013203004128 U CN2013203004128 U CN 2013203004128U CN 201320300412 U CN201320300412 U CN 201320300412U CN 203313482 U CN203313482 U CN 203313482U
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Abstract
The utility model discloses an LED drive circuit. The LED drive circuit comprises an AC/DC circuit, a DC/DC circuit and a drive module. The drive module includes a low-frequency error amplifier, a multiplier, a peak value comparison amplifier, a drive and control circuit and a zero-cross detection circuit. A first input terminal of the multiplier is connected with the anode of an output terminal of the AC/DC circuit, and a second input terminal of the multiplier is connected with an output terminal of the low-frequency error amplifier. An output terminal of the multiplier is connected with a first input terminal of the peak value comparison amplifier, and a second input terminal of the peak value comparison amplifier and an input terminal of the low-frequency error amplifier are connected to the joint of a switch transistor and a sampling resistor. An input terminal of the zero-cross detection circuit is connected with the anode of a diode of the DC/DC circuit, and an output terminal of the zero-cross detection circuit is connected with a first input terminal of the drive and control circuit. An output terminal of the peak value comparison amplifier is connected with a second input terminal of the drive and control circuit. An output terminal of the drive and control circuit is connected with a control terminal of the switch transistor. The LED drive circuit provided by the utility model does not require an auxiliary winding for power supply, and has the advantages of small size and high power factor.
Description
[technical field]
The utility model relates to LED and drives application, relates in particular to a kind of LED drive circuit.
[background technology]
The power saving of illumination more and more comes into one's own at home, plays China on October 1st, 2012 and forbids selling and 100 watts of imports and above general lighting incandescent lamp; On October 1st, 2014 rose, and China will forbid selling and 60 watts of imports and above general lighting incandescent lamp.The application of great power LED is a development trend, and country has strengthened support and the subsidy to the LED development in recent years, has also accelerated the rapid growth of LED illumination.
In the time of the development of LED illumination, also be with and serve technical problem, country also requires more and more higher to requirement and the LED lamp of high-power electronic device power factor to cost and size.
Fig. 1 is the common LED drive circuit, and its constant current control mode is as follows:
During switching tube Q1 conducting, the electric current of rectifier bridge output, from by the LED load, flows through inductance L 1 and sampling resistor R1 to ground.When switching tube Q1 closed, the electric current on inductance L 1 arrived load LED by sustained diode 1 again and forms a loop, kept LED to have electric current to flow through.The size of current of voltage on sampling resistor R1 on can feedback inductance L1, and loop compensation electric capacity is discharged and recharged, the size of this capacitance voltage has influence on internal controller and controls the length control to Q1 switching tube ON time, thereby reaches the purpose of controlling constant current.Control chip U1 is by auxiliary winding power supply, and the drive circuit volume is large, cost is high, and unfixed ON time causes the PFC value lower.
[summary of the invention]
The technical problems to be solved in the utility model is to provide a kind of small volume, LED drive circuit that power factor (PF) is higher.
In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is, a kind of LED drive circuit, comprise the AC/DC change-over circuit, DC/DC conversion switch and driver module, described driver module comprise low frequency aberration amplifier, multiplier, peak value comparison amplifier, driving and control circuit and zero cross detection circuit; The DC/DC conversion switch comprises switching tube, inductance, output capacitance, diode and sampling resistor; The positive pole of AC/DC change-over circuit output connects the positive pole of DC/DC conversion switch output, the minus earth of AC/DC change-over circuit output; The negative pole of one termination DC/DC conversion switch output of inductance, the anode of another terminating diode, the negative electrode of diode connects the positive pole of DC/DC conversion switch output; One end of switching tube is by sampling resistor ground connection, the anode of another terminating diode; Output capacitance is attempted by between the both positive and negative polarity of DC/DC conversion switch output; The first input end of multiplier connects the positive pole of AC/DC change-over circuit output, the output of the second input termination low frequency aberration amplifier; The output termination peakedness ratio of multiplier is than the first input end of amplifier, the second input of peak value comparison amplifier and the input termination switch pipe of low frequency aberration amplifier and the tie point of sampling resistor; The anode of the input terminating diode of zero cross detection circuit, the output termination driving of zero cross detection circuit and the first input end of control circuit, the output termination driving of peak value comparison amplifier and the second input of control circuit, the control end of the output termination switching tube of driving and control circuit.
Above-described LED drive circuit, described switching tube are metal-oxide-semiconductor, and the grid level of metal-oxide-semiconductor connects the output of driving and control circuit, and source electrode is by sampling resistor ground connection, and drain electrode connects the anode of diode.
Above-described LED drive circuit, described zero cross detection circuit comprise JFET pipe, the second diode, the second capacitor C 2, the second metal-oxide-semiconductor, operational amplifier, the first feedback resistance, the second feedback resistance and comparator; The source electrode of JFET pipe is as the anode of the input terminating diode of zero cross detection circuit, and the drain electrode of JFET pipe connects the anode of the second diode, JFET pipe grid level ground connection; The negative electrode of the second diode connects the drain electrode of the second metal-oxide-semiconductor, and the source electrode of the second metal-oxide-semiconductor connects the positive pole of chip power supply power supply; After the first feedback resistance, the second feedback resistance serial connection, the source electrode of termination second metal-oxide-semiconductor, other end ground connection; Anti-phase input termination first feedback resistance of operational amplifier and the tie point of the second feedback resistance, in-phase input end connects the first reference voltage, the grid level of output termination the second metal-oxide-semiconductor; The positive pole of the first input end termination power supply of comparator U3, second input termination the second reference voltage, output as the output termination of zero cross detection circuit, drive and the first input end of control circuit; The positive pole of one chip termination power supply of the second electric capacity, other end ground connection.
The utility model LED drive circuit does not need auxiliary winding power supply, small volume, and can reach constant current and higher power factor (PF) value.
[accompanying drawing explanation]
Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.
Fig. 1 is the circuit diagram of prior art LED drive circuit.
Fig. 2 is the circuit diagram of the utility model embodiment LED drive circuit.
Fig. 3 is the output voltage wave figure of each node of the utility model embodiment LED drive circuit.
Fig. 4 is the schematic diagram of the utility model embodiment zero cross detection circuit.
Fig. 5 is the sequential chart of the utility model embodiment zero cross detection circuit.
[embodiment]
The structure of the utility model embodiment LED drive circuit as shown in Figure 2, comprises the AC/DC change-over circuit, DC/DC conversion switch and driver module.The input termination civil power of AC/DC change-over circuit, DC/DC conversion switch output is as the output termination LED lamp string of LED drive circuit.
Wherein, driver module comprises low frequency aberration amplifier, multiplier, peak value comparison amplifier (peak detection circuit), driving and control circuit and zero cross detection circuit.
The DC/DC conversion switch comprises metal-oxide-semiconductor Q1, inductance L 1, output capacitance C1, diode D1 and resistance R 1, the R2 as switching tube.
The positive pole of AC/DC change-over circuit output connects the positive pole of DC/DC conversion switch output, the minus earth of AC/DC change-over circuit output.
The negative pole of one termination DC/DC conversion switch output of inductance L 1, the anode of another terminating diode D1, the negative electrode of diode D1 connects the positive pole of DC/DC conversion switch output.The source electrode of metal-oxide-semiconductor Q1 is by sampling resistor R1 ground connection, and drain electrode connects the anode of diode D1.Output capacitance C1 is attempted by between the both positive and negative polarity of DC/DC conversion switch output.
The first input end of multiplier connects the positive pole of AC/DC change-over circuit output, the output of the second input termination low frequency aberration amplifier, and the output termination peakedness ratio of multiplier is than the first input end of amplifier.
The source electrode of the input termination metal-oxide-semiconductor Q1 of the second input of peak value comparison amplifier and low frequency aberration amplifier, (tie point of metal-oxide-semiconductor Q1 and sampling resistor R1).
The anode of the input terminating diode D1 of zero cross detection circuit, the output termination driving of zero cross detection circuit and the first input end of control circuit.
The output termination driving of peak value comparison amplifier and the second input of control circuit, the grid level of the output termination metal-oxide-semiconductor Q1 of driving and control circuit.
The low frequency aberration amplifier, by detecting the voltage of sampling resistor R1 in the switching tube conducting, carrys out the variable quantity of the electric current of feedback inductance L1, and delivers to multiplier.
Multiplier is to the voltage sample of the output of AC/DC change-over circuit and multiply each other with the output voltage from the low frequency aberration amplifier, and the result of multiplier computing inputs to peak value comparison amplifier (peak detection circuit).
The peak value comparison amplifier, by detecting the voltage of sampling resistor R1 in the switching tube conducting, carrys out the variable quantity of the electric current of feedback inductance L1, and the output shutdown signal of comparing with the magnitude of voltage of multiplier output, delivers to and drives and control circuit.
The voltage that zero cross detection circuit detects diode D1 anode feeds back the zero passage moment of the output of AC/DC change-over circuit, and zero cross signal is delivered to and driven and control circuit.
Driving and control circuit, according to the shutdown signal of peak value comparison amplifier output and the zero cross signal of zero cross detection circuit output, are controlled the opening and closing of metal-oxide-semiconductor Q1.
The low frequency aberration amplifier is an operational amplifier that bandwidth is very low, and the negative feedback end (inverting input) of operational amplifier connects sampling resistor R1 mono-end, and positive sampling end (in-phase input end) connects reference voltage source.Inner reference voltage and sampling resistor R1 are when switching tube Q1 conducting, and to because of inductance L 1 output current detected voltage on sampling resistor R1, comparing, comparative result is also delivered to the size that multiplier is controlled multiplier sampling and outputting voltage amount.Because the low frequency aberration amplifier is operated in low bandwidth, so the value of the average sample in the cycle is constant at an AC, thereby reach the constant current output purpose.
Multiplier consists of a two-phase multiplier, to multiply each other from the AC signal of AC/DC change-over circuit output sampling and the voltage of low frequency aberration amplifier output, the output voltage drawn is as the input of peak value comparison amplifier, the reference voltage of comparing as the voltage on sampling resistor R1 when the switching tube Q1 conducting, the synchronous variation that this reference voltage is being followed AC/DC change-over circuit output signal is simultaneously relevant to low frequency amplifier output voltage ratio, the phase place that makes the output current of switching tube Q1 follow input voltage changes the PF value and the constant output that reach high.
The peak value comparison amplifier is comprised of a fast amplifier and peak value reference voltage, the end of the inverting input access sampling resistor R1 of fast amplifier, and the in-phase input end of fast amplifier connects the multiplier output voltage.The peak value comparison amplifier compares the magnitude of voltage that the reaction inductive current on multiplier output voltage and sampling resistor R1 changes.When the voltage on sampling resistor R1 is greater than the voltage of multiplier output, by output signal, go to control and drive and the output of control circuit carrys out the output of closing switch pipe Q1, the value that makes the transmission of electricity stream of switching tube Q1 equal to set.
The structure of zero cross detection circuit as shown in Figure 4, comprises JFET pipe, the second diode D2, capacitor C 2, metal-oxide-semiconductor Q2, operational amplifier U2, feedback resistance R4, R5 and comparator U3.The source electrode of JFET pipe is as the anode of the input terminating diode D1 of zero cross detection circuit, and the drain electrode of JFET pipe connects the anode of the second diode D2, JFET pipe grid level ground connection.The negative electrode of the second diode D2 connects the drain electrode of metal-oxide-semiconductor Q2, and the source electrode of metal-oxide-semiconductor Q2 meets the anodal VCC of chip power supply power supply.After feedback resistance R4 and R5 serial connection, the source electrode of a termination metal-oxide-semiconductor Q2, other end ground connection.The anti-phase input terminating resistor R4 of operational amplifier U2 and the tie point of R5, in-phase input end meet the first reference voltage V ref0, the grid level of output termination metal-oxide-semiconductor Q2.Comparator U3 in-phase input end connects the source electrode (the anodal VCC of power supply) of metal-oxide-semiconductor Q2, anti-phase input termination the second reference voltage V ref1, and the output of comparator U3 is as the output termination driving of zero cross detection circuit and the first input end of control circuit.One termination comparator U3 in-phase input end (the anodal VCC of chip power supply power supply) of capacitor C 2, other end ground connection.
When the voltage of zero passage detection sampling end inductance L 1 and metal-oxide-semiconductor Q1 drain electrode joint one end was greater than JFET pipe source terminal voltage, the rectifier bridge output voltage charged through LED lamp and 1 pair of capacitor C 2 of inductance L, the rising of VCC voltage.Metal-oxide-semiconductor Q2, the voltage stabilizing circuit that resistance R 4, R5 and operational amplifier U2 form makes the VCC Voltage-output tend towards stability.The voltage that detects sampling end inductance L 1 and metal-oxide-semiconductor Q1 drain electrode joint one end when zero passage be less than JFET pipe source terminal voltage the charging of capacitor C 2 stop, now correspond to the electric current of inductance L 1 near zero current constantly, because the VCC point of capacitor C 2 one ends is also as the supply output of other modular circuit, now capacitor C 2 voltage that connects VCC mono-end there will be by a small margin and descends.To drop to while being less than zero-crossing comparator U3 reference voltage V REF1 corresponding inductance L 1 electric current be moment of zero when capacitor C 2 connects VCC mono-terminal voltage, comparator U3 output HIGH voltage now, be zero passage detection signal ZCD, ZCD controls the unlatching of metal-oxide-semiconductor Q1 by driving and control circuit.
In sum, zero cross detection circuit sampling inductance L 1 and Q1 drain electrode joint one terminal voltage, this point voltage is greater than JFET source terminal voltage and JFET has electric current to flow through, when inductance L 1 was less than JFET pipe source terminal voltage with metal-oxide-semiconductor Q1 drain electrode joint one terminal voltage, the variation of corresponding inductance L 1 electric current reached and zero passage; Comparator U3 constantly produces a reset signal in inductance L 1 zero passage and again opens metal-oxide-semiconductor Q1.
The utility model is sampled by the voltage that inductance L 1 is applied on sampling resistor R1, and the output of comparing with low frequency aberration amplifier reference voltage, multiplier multiplies each other the sampled voltage of low frequency aberration amplifier output voltage and multiplier to export and delivers to the peak value comparison amplifier.The output of low frequency aberration amplifier changes with also following negative correlation when the change in voltage on sampling resistor R1, and multiplier output is also being followed and changed, thereby reaches average current controlling of sampling purpose.
After switching tube Q1 opened, the voltage on sampling resistor R1 constantly increased, and now the peak value comparison amplifier can detect this maximum voltage value.As shown in Figure 2, peak value comparison amplifier one end is relatively from the output of multiplier, and the other end is relatively inputted from the voltage change on sampling resistor R1.The fiducial value that voltage on sampling resistor R1 is greater than the peak value comparison amplifier switching tube Q1 can be closed, and the electric current on inductance also correspondingly reduces.
When the electric current of switching tube Q1 drops to 0, by zero cross detection circuit, export a start signal, switching tube Q1 is reopened, electric current increases, and the curent change on switching tube Q1 is as shown in switching tube Q1 current waveform in Fig. 3.The utility model has reached the controlled reference voltage that is formed on the low frequency aberration amplifier of LED average current by above-mentioned control procedure.Electric current on inductance follows the phase place of ac input voltage to change, and reaches the output of LED lamp constant current and high PF value with this.
Thereby the above embodiment of the utility model again opens and has controlled output current and following the input voltage same-phase by zero cross detection circuit when the electric current on inductance L 1 is 0, thereby reaches high power factor (PF) value.The low frequency aberration amplifier makes from the voltage on resistance R 1 that the average current of switching tube is controlled is formed on reference voltage and irrelevant with other element, reaches each period L ED constant current output.The above embodiment of the utility model does not need auxiliary winding power supply, small volume, and can reach constant current and high FP value.
The LED output current value is shown below:
Wherein, Iout is the electric current that of LED drive circuit; Vref is the reference voltage of low frequency aberration amplifier; R1 is the sampling resistor in control circuit.
The above embodiment major control of the utility model mode have following some:
One, by the voltage on low frequency aberration amplifier sampling resistor R1, make the size of control switch pipe output current exactly.
Two, by multiplier, sample and phase place that zero cross detection circuit makes the output current phase place can follow ac input voltage changes and in the CCM pattern.And the size of switching tube output current multiplies each other and carries out negative feedback control and make constant output current by multiplier and sampled voltage.
Three, by zero cross detection circuit, carry out the peak current of the maximum of controlling resistance R1, the current peak of control switch pipe Q1 is followed the AC input signal and is changed.
Claims (3)
1. LED drive circuit, comprise the AC/DC change-over circuit, DC/DC conversion switch and driver module, is characterized in that, described driver module comprises low frequency aberration amplifier, multiplier, peak value comparison amplifier, driving and control circuit and zero cross detection circuit; The DC/DC conversion switch comprises switching tube, inductance, output capacitance, diode and sampling resistor; The positive pole of AC/DC change-over circuit output connects the positive pole of DC/DC conversion switch output, the minus earth of AC/DC change-over circuit output; The negative pole of one termination DC/DC conversion switch output of inductance, the anode of another terminating diode, the negative electrode of diode connects the positive pole of DC/DC conversion switch output; One end of switching tube is by sampling resistor ground connection, the anode of another terminating diode; Output capacitance is attempted by between the both positive and negative polarity of DC/DC conversion switch output; The first input end of multiplier connects the positive pole of AC/DC change-over circuit output, the output of the second input termination low frequency aberration amplifier; The output termination peakedness ratio of multiplier is than the first input end of amplifier, the second input of peak value comparison amplifier and the input termination switch pipe of low frequency aberration amplifier and the tie point of sampling resistor; The anode of the input terminating diode of zero cross detection circuit, the output termination driving of zero cross detection circuit and the first input end of control circuit, the output termination driving of peak value comparison amplifier and the second input of control circuit, the control end of the output termination switching tube of driving and control circuit.
2. LED drive circuit according to claim 1, is characterized in that, described switching tube is metal-oxide-semiconductor, and the grid level of metal-oxide-semiconductor connects the output of driving and control circuit, and source electrode is by sampling resistor ground connection, and drain electrode connects the anode of diode.
3. LED drive circuit according to claim 1, is characterized in that, described zero cross detection circuit comprises JFET pipe, the second diode, the second capacitor C 2, the second metal-oxide-semiconductor, operational amplifier, the first feedback resistance, the second feedback resistance and comparator; The source electrode of JFET pipe is as the anode of the input terminating diode of zero cross detection circuit, and the drain electrode of JFET pipe connects the anode of the second diode, JFET pipe grid level ground connection; The negative electrode of the second diode connects the drain electrode of the second metal-oxide-semiconductor, and the source electrode of the second metal-oxide-semiconductor connects the positive pole of chip power supply power supply; After the first feedback resistance, the second feedback resistance serial connection, the source electrode of termination second metal-oxide-semiconductor, other end ground connection; Anti-phase input termination first feedback resistance of operational amplifier and the tie point of the second feedback resistance, in-phase input end connects the first reference voltage, the grid level of output termination the second metal-oxide-semiconductor; The positive pole of the first input end termination power supply of comparator U3, second input termination the second reference voltage, output as the output termination of zero cross detection circuit, drive and the first input end of control circuit; The positive pole of one chip termination power supply of the second electric capacity, other end ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203004128U CN203313482U (en) | 2013-05-27 | 2013-05-27 | LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203004128U CN203313482U (en) | 2013-05-27 | 2013-05-27 | LED drive circuit |
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| Publication Number | Publication Date |
|---|---|
| CN203313482U true CN203313482U (en) | 2013-11-27 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013203004128U Withdrawn - After Issue CN203313482U (en) | 2013-05-27 | 2013-05-27 | LED drive circuit |
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| CN (1) | CN203313482U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103281829A (en) * | 2013-05-27 | 2013-09-04 | 深圳市耐明光电有限公司 | LED driving circuit |
| CN107249235A (en) * | 2017-08-09 | 2017-10-13 | 上海灿瑞科技股份有限公司 | A kind of LED drive circuit of compatible tape light switch |
-
2013
- 2013-05-27 CN CN2013203004128U patent/CN203313482U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103281829A (en) * | 2013-05-27 | 2013-09-04 | 深圳市耐明光电有限公司 | LED driving circuit |
| CN103281829B (en) * | 2013-05-27 | 2015-09-02 | 深圳市耐明光电有限公司 | A kind of LED drive circuit |
| CN107249235A (en) * | 2017-08-09 | 2017-10-13 | 上海灿瑞科技股份有限公司 | A kind of LED drive circuit of compatible tape light switch |
| CN107249235B (en) * | 2017-08-09 | 2023-09-01 | 上海灿瑞微电子有限公司 | LED drive circuit compatible with indicator light switch |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20131127 Effective date of abandoning: 20150902 |
|
| RGAV | Abandon patent right to avoid regrant |