CN102612196B - LED (Light Emitting Diode) constant-current drive circuit and LED lamp using same - Google Patents
LED (Light Emitting Diode) constant-current drive circuit and LED lamp using same Download PDFInfo
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- CN102612196B CN102612196B CN201110022605.7A CN201110022605A CN102612196B CN 102612196 B CN102612196 B CN 102612196B CN 201110022605 A CN201110022605 A CN 201110022605A CN 102612196 B CN102612196 B CN 102612196B
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Abstract
The invention belongs to the field of LED (Light Emitting Diode) drive circuits and discloses an LED constant-current drive circuit and an LED lamp using the same. The LED constant-current drive circuit comprises a power supply, a filtering unit, a constant-current unit and a PWM (Pulse Width Modulation) unit, wherein the filtering unit is electrically connected between the power supply and the constant-current unit, the constant-current unit supplies a constant current to an LED, the PWM unit is electrically connected with the constant-current unit, and the PWM unit controls the constant-current unit through outputting a variable PWM pulse duty factor. The design of the circuit is simple and reliable, and the stepless dimming of the LED can be realized through only changing the variable PWM pulse duty factor output by the PWM unit, so that the circuit has the advantages of simplicity, convenience, stability and reliability.
Description
Technical field
The invention belongs to LED drive circuit, relate in particular to the LED constant-current drive circuit of the wide voltage input of a kind of direct current, constant current output.The invention still further relates to a kind of LED light fixture that uses this LED constant-current drive circuit.
Background technology
LED is as new type light source, and it has energy-saving and environmental protection, feature efficiently, and technology is ripe and be applied to every field, and LED is widely used as lighting source, has also occurred various LED drive circuits thereupon.LED is as constant current operating load, and because LED self is harsher to operating voltage requirement, overtension is too low all can cause LED work undesired, so the power supply quality of supply voltage directly affects the reliability of LED.People are accustomed to carrying out driving LED by constant current chip technology at present, it has the advantages such as power consumption is little, efficiency is high, unit power volume is little, lightweight, but its output current is fixed, can not output current be set by external devices, can not carry out the control of PWM stepless dimming, to user, bring serious inconvenience.
Summary of the invention
Based on the problems referred to above, the object of the present invention is to provide a kind of LED constant-current drive circuit.Another object of the present invention is to provide a kind of LED light fixture that uses this LED constant-current drive circuit.
Technical scheme of the present invention is as follows:
A LED constant-current drive circuit, comprises power supply, filter unit, constant current unit and PWM unit; Described filter unit is connected electrically between described power supply and constant current unit, described constant current unit provides constant electric current for follow-up load, described PWM unit is electrically connected to described constant current unit, and described PWM unit is by constant current unit described in the pwm pulse Duty ratio control of exporting change;
Wherein, described PWM unit comprises control chip U2, the first divider resistance R1 and the second divider resistance R2; The working power input pin of described control chip U2 is electrically connected to the power output end of described filter unit; Described the first divider resistance R1 is connected in series between the working power input pin and light modulation sampling pin of described control chip U2, the light modulation sampling pin of described control chip U2 is by the second divider resistance R2 ground connection, and the PWM light modulation output pin of described control chip U2 is electrically connected to described constant current unit.
Described LED constant-current drive circuit, wherein, described control chip U2 model be MC68HC908QT2.
Described LED constant-current drive circuit, wherein, described the first divider resistance R1 is variable resistor.
Described LED constant-current drive circuit, wherein, described constant current unit comprises constant current chip U1, energy storage inductor L1 and voltage sample resistance R 3, the working power input pin of described constant current chip U1 is electrically connected to the tie point between the power output end of described filter unit and the working power input pin of described control chip U2, described energy storage inductor L1 is connected in series between the working power input pin and switch output pin of described constant current chip U1, the feedback pin of described constant current chip U1 is by voltage sample resistance R 3 ground connection, the control pin of described constant current chip U1 is electrically connected to the PWM light modulation output pin of described control chip U2, the switch output pin of described constant current chip U1 connects the positive pole of load, the feedback pin of described constant current chip U1 connects the negative pole of load.
Described LED constant-current drive circuit, wherein, described constant current unit also comprises the second storage capacitor C3, the switch output pin of described constant current chip U1 and the tie point of load positive pole are by described the second storage capacitor C3 ground connection.
Described LED constant-current drive circuit, wherein, described constant current unit also comprises the diode D1 that anti-electric current pours in down a chimney, the positive pole of this diode is electrically connected to the switch output pin of described constant current chip U1, the negative pole of this diode is electrically connected to the positive pole of load, and the electric connection point of described diode cathode and load positive pole is by described the second storage capacitor C3 ground connection.
Described LED constant-current drive circuit, wherein, described constant current chip U1 model be MP1523.
Described LED constant-current drive circuit, wherein, described filter unit comprises the first storage capacitor C1 and filter capacitor C2, and described the first storage capacitor C1 and filter capacitor C2 are connected in parallel respectively between the positive pole of power supply and the tie point and ground of the working power input pin of described control chip U2.
A kind of LED light fixture that uses above-mentioned LED constant-current drive circuit.
The LED constant-current drive circuit of circuit of the present invention, in PWM unit, pass through to change the resistance of variable resistor R1 place in circuit, and then the duty ratio of the pwm pulse of the 6 pin outputs of change control chip U2, reach the control pin of controlling constant current chip U1, i.e. 4 pin (EN), export different constant current value, thereby realize LED stepless dimming, meet the demand of people to light modulation.
Accompanying drawing explanation
Fig. 1 is the block diagram of LED constant-current drive circuit of the present invention;
Fig. 2 is the circuit theory diagrams of an embodiment of LED constant-current drive circuit of the present invention.
Embodiment
Below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in further detail.
The invention provides a kind of LED constant-current drive circuit, as shown in Figure 1, this LED constant-current drive circuit comprises that (the present invention adopts 3.7V DC power supply to power supply 100, as disposable battery or rechargeable battery), filter unit 200, constant current unit 300, and PWM unit 500.Filter unit 200 is connected electrically between the positive pole and constant current unit 300 of power supply 100, constant current unit 300 provides constant electric current for load (LED400), PWM unit 500 is electrically connected to constant current unit 300, this PWM unit 500 is by the pwm pulse Duty ratio control constant current unit 300 of exporting change, thereby realize LED 400 stepless dimmings, meet the demand of people to light modulation.
As shown in Figure 2, PWM unit 500 comprises that model is control chip U2, the first divider resistance R1 and the second divider resistance R2 of MC68HC908QT2; The working power input pin of control chip U2,1 pin (VDD) is electrically connected to the positive pole of the power output end of filter unit 200; The first divider resistance R1 is variable resistor, it is connected in series in working power input pin and the light modulation sampling pin of control chip U2, between 3 pin (PAT4), the light modulation sampling pin of control chip U2 is by the second divider resistance R2 ground connection, and the PWM light modulation output pin of control chip U2 is electrically connected to constant current unit; 8 pin (VSS) of control chip U2 are GND pin, are directly connected with the negative pole of power supply; 2,4,5,6 pin are vacant pin, unsettledly do not define.
As shown in Figure 2, constant current unit 300 comprises that model is the constant current chip U1 of MP1523, energy storage inductor L1, and voltage sample resistance R 3.The working power input pin of constant current chip U1,5 pin (VCC) are electrically connected to the tie point between the power output end positive pole of filter unit 200 and the working power input pin of control chip U2, and the working power input pin of control chip U2 and the working power input pin point of constant current chip U1 are electrically connected at the power output end positive pole with filter unit 200 after being connected; Energy storage inductor L1 is connected in series in working power input pin and the switch output pin of constant current chip U1, between 1 pin (SW), the feedback pin of constant current chip U1,3 pin (FB) are by voltage sample resistance R 3 ground connection, the control pin of constant current chip U1,4 pin (EN) are electrically connected to the PWM light modulation output pin of control chip U2, and the switch output pin of constant current chip U1 connects the positive pole of load (LED400), and the feedback pin of described constant current chip U1 connects the negative pole of load (LED400).Wherein, the control pin high level of constant current chip U1 is effective, and low level is invalid.
In practical application, constant current unit 300 also comprised energy storage effect the second storage capacitor C3 and prevent the diode D1 that electric current pours in down a chimney, as shown in Figure 2.The switch output pin of the positive pole of diode D1 and constant current chip U1,1 pin (SW) is electrically connected to, the negative pole of diode D1 is electrically connected to the positive pole of load (LED400), and the electric connection point of the negative pole of diode D1 and load (LED400) positive pole is by the second storage capacitor C3 ground connection.Like this, when down circuitry, the second storage capacitor C3 enters discharge condition, and its discharging current loop is: the second storage capacitor C3, LED400, voltage sample resistance R 3, ground, the second storage capacitor C3; The effect of diode D1 is to prevent that discharging current from pouring in down a chimney to constant current chip U2.Meanwhile, when circuit has interference signal, the second storage capacitor C3 absorbing high-frequency disturbs, and plays energy storage effect, for load LED400 provides high-quality crossing current power supply.
Above-mentioned filter unit 200 comprises the first storage capacitor C1 and filter capacitor C2.The first storage capacitor C1 and filter capacitor C2 are connected in parallel respectively between the positive pole and ground of DC power supply, and be connected in parallel a little as the positive pole of the power output end of filter unit 200, be electrically connected to the working power input pin of control chip U2 and the working power input pin of constant current chip U1.This filter unit 200, in order to guarantee that input supply voltage steadily fluctuates and the high frequency clutter in power supply signal is coupled in filtering, guarantees that supply voltage power supply is stable.
The operation principle of constant current chip U1:
According to voltage sample resistance R 3 pressure drop (being steady state value 0.4V) above, automatically adjust the duty cycle of switching of inner NMOS pipe, between 1 pin of constant current chip U1 and 2 pin (being GND) at the inner integrated NMOS pipe of U1, NMOS pipe switching frequency is very high, in one-period, open-minded when NMOS pipe, whole current circuit is open-minded to GND through 1 pin of energy storage inductor L1, constant current chip U1, energy storage inductor L1 storage power, LED operating current maintains by the electric weight of the second storage capacitor C3; When NMOS pipe is closed, whole current circuit forms loop through energy storage inductor L1, diode D1, LED, voltage sample resistance R 3, the electric energy of energy storage inductor L1 is superimposed with the electric energy of power supply, so just output voltage is raise, LED operating current is supplied with jointly by power supply and energy storage inductor L1, until next cycle NMOS pipe is open-minded, thereby reaches the object of constant current, as long as sampling resistor R3 resistance is definite, exports so constant current and determine.The 3 pin sampling pin of constant current chip U1 and the reference voltage source of constant current chip U1 inside form a comparator, sampling heel according to sampled voltage and reference voltage relatively after, it is open-minded that the inside of constant current chip U1 is adjusted control NMOS pipe automatically, close the duty ratio of pulse, if sampled voltage is greater than reference voltage (0.4V), illustrate that output current is greater than set point (20mA), the duty ratio of pulse just increases so, reduce output current to set point, if sampled voltage is less than reference voltage, illustrate that output current is less than set point, the duty ratio of pulse just reduces so, increase output current to set point, thereby realize the constant current work of LED.
This LED constant-current drive circuit specific implementation principle is as follows:
Switch S 1 when closed power supply 100, circuit obtains electric, constant current chip U1 and control chip U2 obtain electric, as the first divider resistance R1, be that variable resistor R1 access resistance is while being zero, now the operating current on control chip U2 is maximum, the voltage signal that control chip U2 samples according to 3 pin, make its 7 pin output pwm pulse (being now output as normal high level) to 4 pin of constant current chip U1, constant current chip U14 pin is enabled, constant current chip U1 obtains electric and starts working, DC power supply is through energy storage inductor L1, diode D1, LED, voltage sample resistance R 3 forms work loop, under the control of constant current chip U1, exporting constant current is LED power supply, LED obtains electric beginning with constant current work, only need the resistance that changes voltage sample resistance R 3 just can design LED operating current, circuit is simple and convenient, reliable and stable.
When increasing the resistance of variable resistor R1 place in circuit, 6 pin of control chip U2 can change the duty ratio of output pwm pulse, control the control pin of constant current chip U1, i.e. 4 pin (EN), variation along with variable resistor R1 resistance, the duty ratio of the 6 pin output pwm pulses of control chip U2 also can change, and by regulating the duty of PWM recently to realize LED stepless dimming, meets the demand of people to light modulation.
A LED light fixture, as LED flashlight, LED mine lamp etc., this LED light fixture comprises above-mentioned LED constant-current drive circuit.
Should be understood that, the above-mentioned statement for preferred embodiment of the present invention is comparatively detailed, can not therefore think the restriction to scope of patent protection of the present invention, and scope of patent protection of the present invention should be as the criterion with claims.
Claims (7)
1. a LED constant-current drive circuit, comprises power supply, filter unit, constant current unit and PWM unit; Wherein, described filter unit is connected electrically between described power supply and constant current unit, described constant current unit provides constant electric current for follow-up load, and described PWM unit is electrically connected to described constant current unit, and described PWM unit is by constant current unit described in the pwm pulse Duty ratio control of exporting change;
It is characterized in that, described PWM unit comprises control chip U2, the first divider resistance R1 and the second divider resistance R2; The working power input pin of described control chip U2 is electrically connected to the power output end of described filter unit; Described the first divider resistance R1 is connected in series between the working power input pin and light modulation sampling pin of described control chip U2; the light modulation sampling pin of described control chip U2 is by the second divider resistance R2 ground connection; the PWM light modulation output pin of described control chip U2 is electrically connected to described constant current unit; the model of described control chip U2 is MC68HC908QT2, and described the first divider resistance R1 is variable resistor; When circuit obtains electricly, when the first divider resistance R1 access resistance is zero, now the operating current on control chip U2 is maximum.
2. LED constant-current drive circuit according to claim 1, is characterized in that, described constant current unit comprises constant current chip U1, energy storage inductor L1 and voltage sample resistance R 3, the working power input pin of described constant current chip U1 is electrically connected to the tie point between the power output end of described filter unit and the working power input pin of described control chip U2, described energy storage inductor L1 is connected in series between the working power input pin and switch output pin of described constant current chip U1, the feedback pin of described constant current chip U1 is by voltage sample resistance R 3 ground connection, the control pin of described constant current chip U1 is electrically connected to the PWM light modulation output pin of described control chip U2, the switch output pin of described constant current chip U1 connects the positive pole of load, the feedback pin of described constant current chip U1 connects the negative pole of load.
3. LED constant-current drive circuit according to claim 2, is characterized in that, described constant current unit also comprises the second storage capacitor C3, and the switch output pin of described constant current chip U1 and the tie point of load positive pole are by described the second storage capacitor C3 ground connection.
4. LED constant-current drive circuit according to claim 3, it is characterized in that, described constant current unit also comprises the diode D1 that anti-electric current pours in down a chimney, the positive pole of this diode is electrically connected to the switch output pin of described constant current chip U1, the negative pole of this diode is electrically connected to the positive pole of load, and the electric connection point of described diode cathode and load positive pole is by described the second storage capacitor C3 ground connection.
5. LED constant-current drive circuit according to claim 2, is characterized in that, described constant current chip U1 model be MP1523.
6. LED constant-current drive circuit according to claim 1, it is characterized in that, described filter unit comprises the first storage capacitor C1 and filter capacitor C2, and described the first storage capacitor C1 and filter capacitor C2 are connected in parallel respectively between the positive pole of power supply and the tie point and ground of the working power input pin of described control chip U2.
7. a LED light fixture, is characterized in that, comprises the arbitrary described LED constant-current drive circuit of claim 1 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110022605.7A CN102612196B (en) | 2011-01-20 | 2011-01-20 | LED (Light Emitting Diode) constant-current drive circuit and LED lamp using same |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110022605.7A CN102612196B (en) | 2011-01-20 | 2011-01-20 | LED (Light Emitting Diode) constant-current drive circuit and LED lamp using same |
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| CN102612196A CN102612196A (en) | 2012-07-25 |
| CN102612196B true CN102612196B (en) | 2014-04-02 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9572210B2 (en) | 2012-12-28 | 2017-02-14 | Silicon Works Co., Ltd. | Control circuit of light-emitting diode lighting apparatus |
| CN104768261A (en) * | 2014-01-02 | 2015-07-08 | 深圳市海洋王照明工程有限公司 | Dimming LED constant-current driving circuit |
| CN105430843B (en) * | 2015-12-02 | 2023-08-04 | 上海航空电器有限公司 | Anti-collision lamp circuit with LED constant voltage constant current drive and stroboscopic control |
| CN106773452B (en) * | 2017-02-17 | 2022-06-14 | 常熟博兴光电技术有限公司 | Camera light source linkage control digital power supply |
| CN108882433B (en) * | 2017-11-09 | 2020-07-14 | 李淑媛 | Light-emitting diode lighting device capable of stably dimming and stable dimming method |
| CN111111016A (en) * | 2020-02-20 | 2020-05-08 | 深圳远致富海智能产业有限公司 | LED lamp appearance that moults |
| CN112333887B (en) * | 2020-10-14 | 2023-03-14 | 深圳篆意科技有限公司 | LED drive circuit |
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| CN201416786Y (en) * | 2009-04-27 | 2010-03-03 | 杰欧比摄影器材有限公司 | LED light system |
| JP2010200321A (en) * | 2009-02-24 | 2010-09-09 | Richard Landry Gray | Pulse width modulation control device |
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| JP2008060222A (en) * | 2006-08-30 | 2008-03-13 | Seiko Epson Corp | Device and method for driving light-emitting element |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010200321A (en) * | 2009-02-24 | 2010-09-09 | Richard Landry Gray | Pulse width modulation control device |
| CN201416786Y (en) * | 2009-04-27 | 2010-03-03 | 杰欧比摄影器材有限公司 | LED light system |
Non-Patent Citations (1)
| Title |
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| MPS.MP1523 Precision 6-lamp white LED Drive,Rev.1.6.《MP1523》.www.alldatasheet.com,2004,第1-7页. * |
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