CN104883782A - LED switch driving circuit with low cost - Google Patents
LED switch driving circuit with low cost Download PDFInfo
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- CN104883782A CN104883782A CN201510273817.0A CN201510273817A CN104883782A CN 104883782 A CN104883782 A CN 104883782A CN 201510273817 A CN201510273817 A CN 201510273817A CN 104883782 A CN104883782 A CN 104883782A
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Abstract
The invention discloses a LED switch driving circuit with low cost. The circuit is characterized in that the circuit comprises a LED conductive loop, an input filtering circuit and a PWM controller; the LED conductive loop comprises a current detection resistor R1, an inductor L2, a LED and a freewheel diode D1; the current detection resistor R1 is connected to a 7 pin of the PWM controller and an anode of the LED; the controller works in a current limit mode; when a built-in power switch is started, the LED is conducted; when a LED conducted current is increased to a certain value, a comparator closes the built-in power switch; a PWM driving current with a certain frequency is output. The structure of the switch driving circuit is simple and cost is low. The circuit can be applied to occasions of a civil electrical appliance, a handheld device and the like, where people are concerned about design cost.
Description
Technical field
The present invention relates to LED drive power field, particularly a kind of LED switch drive circuit of low cost.
Background technology
Along with the decline of LED production cost and the raising of luminous efficiency, the application of LED in various equipment gets more and more, as family expenses, vehicle-mounted and architectural lighting etc.Compare with traditional lighting source, LED has the advantage such as high reliability, high-luminous-efficiency, fast response.But LED has higher requirement to drive circuit.No matter how input voltage changes, and driving power must export a constant electric current and carry out driving LED to reach fixing brightness.In a lot of application scenario, the adjustment for brightness of illumination needs, and LED also has the requirement of light modulation.
LED light modulation mainly contains two kinds of realization means: linear regulation LED current (simulation light modulation) or use PWM switching circuit (digital dimming).Simulation light modulation realizing circuit is simple, but the adjustment of drive current can cause the change of LED light emission color temperature.This is the character due to LED: the characteristics of luminescence offsets along with the change of drive current.For monochromatic LED, its emission wavelength can change; Concerning white light LEDs, its light emission color temperature can change, thus the experience of impact illumination.And simulation light modulation can not ensure high-precision Current adjustment.Drive circuit generally detects electric current based on series resistance, and when light modulation electric current wide variation, metrical error is difficult to avoid, and will reduce the degree of regulation of drive current.
Compare simulation dimming mode, digital dimming has more advantage: LED can not produce color temperature shift; Light modulation precision is high, because PWM control precision is high; Also scintillation etc. is there will not be under large-scale light modulation.Digital controlled signal is converted to PWM drive singal by digital dimming, realizes light modulation, as shown in Figure 1 by the duty ratio changing pulse current.Digitial controller control DC/DC constant-current source exports square wave drive current, and its pulse duration is adjustable, by changing the modulation of LED lighting time into the modulation of drive current width, reduces input power simultaneously, arrives energy-conservation and object that is light modulation.LED works in higher switching frequency, and the eyes due to people have vision hysteresis quality, can not feel the scintillation that light source produces in dimming process.Although digital dimming mode superior performance, realizing circuit is complicated, and need adopt expensive digitial controller, the programming of software too increases the design cost of system.Need in occasions such as some civilian household electrical appliances, handheld devices the PWM switch driving circuit designing low cost, the art of this patent launches research based on such background.
Summary of the invention
The object of the invention is the LED switch drive circuit designing a kind of low cost.
To achieve these goals, embodiments provide a kind of LED switch drive circuit, comprise a LED conducting loop, an input filter circuit and a PWM controller, wherein:
Described LED conducting loop comprises current sense resistor R1, inductance L 2, LED and sustained diode 1.
Described input filter circuit comprises filter inductance L1 and filter capacitor C1.
1 pin of described PWM controller connects one end of inductance L 2; 2 pin of described PWM controller and 4 pin ground connection; 3 pin of described PWM controller connect one end of electric capacity C3.
One end of 5 pin connecting resistance R3 of described PWM controller; 6 pin of described PWM controller connect one end of filter inductance L1; One end of 8 pin connecting resistance R2 of described PWM controller.
Further, 7 pin of a termination PWM controller of described current sense resistor R1 and the positive pole of LED; The negative pole of described LED connects one end of inductance L 2; The other end of described inductance L 2 connects the positive pole of fly-wheel diode D1.
Further, a termination input power of described filter inductance L1; Another termination capacitor C1 of described inductance L 1 and the negative pole of sustained diode 1; The other end ground connection of described electric capacity C1.
Further, described sustained diode 1 adopts Schottky type rectifier diode.
Further, described electric capacity C3 adopts high-accuracy capacitor.
Further, described PWM controller adopts power of fixed frequency managing chip.
Further, described PWM controller adopts MC34063 to realize.
Embodiments provide a kind of LED switch drive circuit.Drive circuit is made up of voltage-releasing voltage stabilizer, and circuit working, in current limit mode, eliminates voltage feedback loop.Compared to the prior art, the present invention, by achieving PWM switch drive pattern based on the analog chip of low cost, has that circuit structure is simple and reliable, low cost and other advantages.
Accompanying drawing explanation
In order to make the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the present invention is described in further detail, wherein:
Fig. 1 is the circuit structure block diagram of existing digital dimming technology;
Fig. 2 is the schematic diagram of LED switch drive circuit of the present invention.
Embodiment
Below in conjunction with accompanying drawing, method of the present invention is described in further detail.
The schematic diagram of the LED switch drive circuit that Fig. 2 provides for the embodiment of the present invention, as shown in the figure, embodiments provides a kind of LED switch drive circuit of low cost, comprises a LED conducting loop, an input filter circuit and a PWM controller, wherein:
Described LED conducting loop comprises current sense resistor R1, inductance L 2, LED and sustained diode 1.
Described input filter circuit comprises filter inductance L1 and filter capacitor C1.
1 pin of described PWM controller connects one end of inductance L 2; 2 pin of described PWM controller and 4 pin ground connection; 3 pin of described PWM controller connect one end of electric capacity C3.
One end of 5 pin connecting resistance R3 of described PWM controller; 6 pin of described PWM controller connect one end of filter inductance L1; One end of 8 pin connecting resistance R2 of described PWM controller.
Further, 7 pin of a termination PWM controller of described current sense resistor R1 and the positive pole of LED; The negative pole of described LED connects one end of inductance L 2; The other end of described inductance L 2 connects the positive pole of fly-wheel diode D1.
Further, a termination input power of described filter inductance L1; Another termination capacitor C1 of described inductance L 1 and the negative pole of sustained diode 1; The other end ground connection of described electric capacity C1.
Further, described sustained diode 1 adopts Schottky type rectifier diode.
Further, described electric capacity C3 adopts high-accuracy capacitor.
Further, described PWM controller adopts power of fixed frequency managing chip.
Further, described PWM controller adopts MC34063 to realize.
The voltage-releasing voltage stabilizer that drive circuit in the embodiment of the present invention is simple by structure, cost is low is formed, and can realize the characteristic of quick light modulation.The controller MC34063 of circuit has internal switch, current limit comparator, oscillator etc.Voltage stabilizing pin has closing function, and the voltage exceeding threshold values understands powered-down, and voltage is reduced to below threshold values meeting power-on.During electric power starting, owing to not having Voltage Feedback, controller works in current limit mode.
When powering on, the starting impulse that oscillator generates causes on-chip power triode to open.Input voltage forms closed-loop path by the built-in triode of current sense resistor R1, LED, inductance L 2 and controller.When electric current increases to the threshold level of current limit comparator, comparator powered-down built-in switch; Inductance L 2 both end voltage is reverse, and sustained diode 1 conducting, until on-chip power switch is opened in next switch periods.For the occasion that some required precisions are not high, PWM controller MC34063 can complete dimming function preferably, and LED can realize PWM light modulation with hundreds of hertz easily.Its error amplifier can provide closing function to realize LED light modulation, and current limit comparator provides accurately and electric current is arranged fast.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (7)
1. a LED switch drive circuit, is characterized in that: comprise a LED conducting loop, an input filter circuit and a PWM controller; Described LED conducting loop comprises current sense resistor R1, inductance L 2, LED and sustained diode 1; Described input filter circuit comprises filter inductance L1 and filter capacitor C1; 1 pin of described PWM controller connects one end of inductance L 2; 2 pin of described PWM controller and 4 pin ground connection; 3 pin of described PWM controller connect one end of electric capacity C3; One end of 5 pin connecting resistance R3 of described PWM controller; 6 pin of described PWM controller connect one end of filter inductance L1; One end of 8 pin connecting resistance R2 of described PWM controller.
2. converter according to claim 1, is characterized in that: 7 pin of a termination PWM controller of described current sense resistor R1 and the positive pole of LED; The negative pole of described LED connects one end of inductance L 2; The other end of described inductance L 2 connects the positive pole of fly-wheel diode D1.
3. converter according to claim 1, is characterized in that: a termination input power of described filter inductance L1; Another termination capacitor C1 of described inductance L 1 and the negative pole of sustained diode 1; The other end ground connection of described electric capacity C1.
4. converter according to claim 2, is characterized in that: described sustained diode 1 adopts Schottky type rectifier diode.
5. converter according to claim 1, is characterized in that: described electric capacity C3 adopts high-accuracy capacitor.
6. the converter according to the arbitrary claim of claim 1 to 2, is characterized in that: described PWM controller adopts power of fixed frequency managing chip.
7. converter according to claim 6, is characterized in that: described PWM controller adopts MC34063 to realize.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510273817.0A CN104883782A (en) | 2015-05-20 | 2015-05-20 | LED switch driving circuit with low cost |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510273817.0A CN104883782A (en) | 2015-05-20 | 2015-05-20 | LED switch driving circuit with low cost |
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| CN104883782A true CN104883782A (en) | 2015-09-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201510273817.0A Pending CN104883782A (en) | 2015-05-20 | 2015-05-20 | LED switch driving circuit with low cost |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101616524A (en) * | 2009-07-29 | 2009-12-30 | 广州复旦奥特科技股份有限公司 | A kind of commercial LED illumination driver |
| CN101674697A (en) * | 2009-09-18 | 2010-03-17 | 陆群 | Miniaturization high power output and separation type driving power supply used by LED bulbs |
| CN101917805A (en) * | 2010-08-09 | 2010-12-15 | 海洋王照明科技股份有限公司 | Led drive circuit |
| CN102651929A (en) * | 2011-02-25 | 2012-08-29 | 海洋王照明科技股份有限公司 | LED (Light-Emitting Diode) driven short-circuit protection circuit |
| US20120235585A1 (en) * | 2009-11-19 | 2012-09-20 | Koninklijke Philips Electronics, N.V. | Method and apparatus selectively determining universal voltage input for solid state light fixtures |
-
2015
- 2015-05-20 CN CN201510273817.0A patent/CN104883782A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101616524A (en) * | 2009-07-29 | 2009-12-30 | 广州复旦奥特科技股份有限公司 | A kind of commercial LED illumination driver |
| CN101674697A (en) * | 2009-09-18 | 2010-03-17 | 陆群 | Miniaturization high power output and separation type driving power supply used by LED bulbs |
| US20120235585A1 (en) * | 2009-11-19 | 2012-09-20 | Koninklijke Philips Electronics, N.V. | Method and apparatus selectively determining universal voltage input for solid state light fixtures |
| CN101917805A (en) * | 2010-08-09 | 2010-12-15 | 海洋王照明科技股份有限公司 | Led drive circuit |
| CN102651929A (en) * | 2011-02-25 | 2012-08-29 | 海洋王照明科技股份有限公司 | LED (Light-Emitting Diode) driven short-circuit protection circuit |
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Application publication date: 20150902 |
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| RJ01 | Rejection of invention patent application after publication |