CN202857087U - Fly-back led constant current source driving circuit - Google Patents
Fly-back led constant current source driving circuit Download PDFInfo
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- CN202857087U CN202857087U CN 201220542125 CN201220542125U CN202857087U CN 202857087 U CN202857087 U CN 202857087U CN 201220542125 CN201220542125 CN 201220542125 CN 201220542125 U CN201220542125 U CN 201220542125U CN 202857087 U CN202857087 U CN 202857087U
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- constant current
- source driving
- current source
- driving circuit
- error amplifier
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Abstract
The utility model discloses a fly-back LED constant current source driving circuit which can continuously convey constant power source for LED lighting elements. The fly-back LED constant current source driving circuit comprises a rectifier circuit, a transformer, a power supply management chip and an error amplifier, wherein a double-pi-shaped LC radio frequency interference filter circuit is arranged between the commercial power supply and the rectifier circuit, an optical coupler is arranged between the error amplifier and the power supply management chip, and an input end of the error amplifier is further provided with a constant current control circuit. Compared with the prior art, according to the fly-back LED constant current source driving circuit, the constant current control circuit is arranged before the error amplifier to form a negative feedback circuit, so the power supply management chip can controls conduction of an internal MOSFET tube based on outputted sampling signals to make a primary loop of the transformer be in a conduction state or in a non-conduction state, and thereby direct current conveyed by the transformer to the load is kept constant, and lighting brightness of the LED is guaranteed to be stable.
Description
Technical field
The utility model relates to a kind of LED lighting circuit, particularly a kind of drive circuit that constant-current source is provided for LED.
Background technology
Along with the develop rapidly of semiconductor lighting technology, the illuminating product of the LED light-emitting diode of the advantages such as luminous efficiency is high by having, long service life, energy-conserving and environment-protective assembling just progressively replaces incandescent lamp and fluorescent lamp.
The luminous intensity of LED is by the size decision of flowing through its electric current, and it's the useful life that conference affects LED is past electric current, and therefore the too small luminosity that can affect LED of electric current, just seems particularly important for LED provides the drive circuit of constant current, burning voltage.
Usually, isolated DC/DC converter is multiplex in led drive circuit, isolatedly can be divided into positive activation type and inverse-excitation type according to version.
Inverse-excitation type refers to secondary cut-off when the transformer primary side conducting, and this moment, stored energy was in transformer; When ended on former limit, the operating state of passing load was paid the energy of storing in the transformer in the secondary conducting; Positive activation type refers to that in transformer primary side conducting secondary induces corresponding voltage and outputs to the operating state of load.
Normal shock and circuit of reversed excitation respectively have its characteristics, for reaching best cost performance, can apply in a flexible way in the process of design circuit.Generally at the optional inverse-excitation type of using of small-power output occasion, can adopt positive activation type in the larger a little power output situation.
Thereby, should adopt inverse-excitation type isolation DC/DC converter for the LED lighting circuit.
In the prior art, inverse-excitation type isolation DC/DC translation circuit need to be in transformer storage power, and because the leakage inductance problem in the transformer, so that its output current mostly is discontinuous mode, the electric current that offers thus LED is non-constant, finally causes the LED luminosity unstable.
Summary of the invention
The technical problems to be solved in the utility model provides a kind of inverse-excitation type LED constant current source driving circuit, and this circuit can be given LED illumination component delivered constant electric current continuously.
In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is:
Inverse-excitation type LED constant current source driving circuit of the present utility model, comprise rectification circuit, transformer, power management chip and error amplifier, between mains-supplied and rectification circuit, also be provided with a two ∏ type LC radio frequency interference filter circuit, be optocoupler between described error amplifier and the power management chip, also be provided with a constant-current control circuit at the error amplifier input.
Described constant-current control circuit is made of voltage reference, divider resistance the 4th resistance, the 5th resistance and output current sampling resistor.
Identical but inductance single spin-echo consists of inductance in the described pair of ∏ type LC radio frequency interference filter circuit by two umber of turns.
Described power management chip is the isolated minitype single-chip Switching Power Supply of enhancement mode integrated chip, and its model is TNY279.
Described optocoupler is linear optical coupling, and its model is PC817A.
The model of described error amplifier is LM358.
Compared with prior art, the utility model arranges constant-current control circuit and consists of negative-feedback circuit before error amplifier, thus, make power management chip control the conducting of its inner MOSFET pipe according to the output sampled signal, even primary loop conducting or close, thereby control transformer is transported to the direct current of load and is kept constant, has guaranteed that the LED luminosity keeps stable.
Description of drawings
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
Fig. 1 is the utility model circuit theory diagrams.
Embodiment
As shown in Figure 1, inverse-excitation type LED constant current source driving circuit of the present utility model comprises rectification circuit 1, transformer T, power management chip U1 and error amplifier U3, wherein, power management chip U1 is the isolated minitype single-chip Switching Power Supply of enhancement mode integrated chip, and its model is TNY279; Error amplifier U3 model is LM358.
The utility model also is provided with a two ∏ type LC radio frequency interference filter circuit 2 between mains-supplied and rectification circuit 1, identical but inductance single spin-echo consists of inductance L 1 in this filter circuit 2 by two umber of turns, the high order harmonic component signal of this filter circuit 2 during effectively the filtering civil power exchanges, be optocoupler U2 between described error amplifier U3 and the power management chip U1, this optocoupler is linear optical coupling U2, its model is PC817A, also is provided with a constant-current control circuit 3 at error amplifier U3 input.
Described constant-current control circuit 3 is made of voltage reference U4, divider resistance the 4th resistance R 4, the 5th resistance R 5 and output current sampling resistor R6.
Transformer T1 is used for the energy transmission between input-output, and when the power MOSFET tube conducting in the power management chip U1, energy storage is in transformer T armature winding, and at this moment, the electric energy that the 7th capacitor C 7 is deposited is load supplying; When the pipe of the MOSEFT among the power management chip U1 turn-offed, the energy of storage was delivered to the secondary winding of transformer T, is load supplying, also was simultaneously 7 chargings of the 7th capacitor C; The first voltage-stabiliser tube D1 and the second voltage-stabiliser tube D2 have consisted of the elementary clamping protection circuit of transformer T, are used for absorbing the spike that is added in when described MOSFET pipe turn-offs in its drain electrode, drain voltage are limited in the safe range, with the protection switch chip; Rectifier diode D3 is the output rectifier diode; The second inductance L 2 and the 6th is held C6 and is consisted of output stage LC filter circuit, the AC ripple that is used for suppressing high-frequency noise and reduces output dc voltage.
Operation principle:
Constant-current control circuit 3 of the present utility model is realized constant output current based on the thinking of negative feedback control by close loop negative feedback.
Sampling resistor R6, the 4th resistance R 4, the 5th resistance R 5, error amplifier U3, voltage reference U4 and optocoupler U2 have consisted of the feedback control loop of circuit jointly.Sampling resistor R6 is for detection of output current, and converts thereof into magnitude of voltage, be used for reference voltage after produce error signal.There is the 2.5V reference voltage source voltage reference U2 inside, according to the difference of connected mode, can obtain the burning voltage of 2.5-36V between its negative electrode and positive electrode.In this circuit, the negative electrode of voltage reference U4 links to each other with the reverse input end (with reference to the utmost point) of error amplifier U3 by the 4th resistance R 4, can between negative electrode and positive electrode, produce stable 2.5V voltage, after the 4th resistance R 4, the 5th resistance R 5 dividing potential drops, be used for the reference voltage of error amplifier U3.Error amplifier U3 produces error signal after sampled signal and reference signal are relatively amplified, to flow through the electric current of light-emitting diode wherein among the control optocoupler U2.The second resistance R 2 and the 8th capacitor C 8 are used for the frequency compensation of error amplifier U3, with the closed loop stability of intensifier circuit and improve circuit dynamically and steady-state behaviour, the 3rd resistance R 3 is current-limiting resistance.Optocoupler U2 transfers to power management chip U1 with current forms with error signal, power management chip U1 detection of error signals is also adjusted conducting and the turn-off time of its inner MOSFET pipe with this, the energy transport of control transformer T, and then keep the constant of output current.
Claims (6)
1. inverse-excitation type LED constant current source driving circuit, comprise rectification circuit (1), transformer (T), power management chip (U1) and error amplifier (U3), it is characterized in that: between mains-supplied and rectification circuit (1), also be provided with a two ∏ type LC radio frequency interference filter circuit (2), be optocoupler (U2) between described error amplifier (U3) and the power management chip (U1), also be provided with a constant-current control circuit (3) at error amplifier (U3) input.
2. inverse-excitation type LED constant current source driving circuit according to claim 1 is characterized in that: described constant-current control circuit (3) is made of voltage reference (U4), divider resistance the 4th resistance (R4), the 5th resistance (R5) and output current sampling resistor (R6).
3. inverse-excitation type LED constant current source driving circuit according to claim 1 and 2 is characterized in that: identical but inductance single spin-echo consists of the inductance (L1) in the described pair of ∏ type LC radio frequency interference filter circuit (2) by two umber of turns.
4. inverse-excitation type LED constant current source driving circuit according to claim 1, it is characterized in that: described power management chip (U1) is the isolated minitype single-chip Switching Power Supply of enhancement mode integrated chip, and its model is TNY279.
5. inverse-excitation type LED constant current source driving circuit according to claim 1, it is characterized in that: described optocoupler is linear optical coupling (U2), and its model is PC817A.
6. inverse-excitation type LED constant current source driving circuit according to claim 1, it is characterized in that: the model of described error amplifier (U3) is LM358.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220542125 CN202857087U (en) | 2012-10-22 | 2012-10-22 | Fly-back led constant current source driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220542125 CN202857087U (en) | 2012-10-22 | 2012-10-22 | Fly-back led constant current source driving circuit |
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| Publication Number | Publication Date |
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| CN202857087U true CN202857087U (en) | 2013-04-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220542125 Expired - Fee Related CN202857087U (en) | 2012-10-22 | 2012-10-22 | Fly-back led constant current source driving circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104682707A (en) * | 2013-11-28 | 2015-06-03 | 深圳市海洋王照明工程有限公司 | Switching power supply for selectable output of voltage |
| CN106376150A (en) * | 2015-07-22 | 2017-02-01 | 山东骏风电子有限公司 | Balance breathing lamp |
| CN109149973A (en) * | 2018-10-08 | 2019-01-04 | 深圳市力生美半导体股份有限公司 | Constant current output control circuit and its design method |
| CN109976439A (en) * | 2019-04-29 | 2019-07-05 | 苏州市职业大学 | High efficiency can multi-path flow equalizing constant-current source circuit |
-
2012
- 2012-10-22 CN CN 201220542125 patent/CN202857087U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104682707A (en) * | 2013-11-28 | 2015-06-03 | 深圳市海洋王照明工程有限公司 | Switching power supply for selectable output of voltage |
| CN106376150A (en) * | 2015-07-22 | 2017-02-01 | 山东骏风电子有限公司 | Balance breathing lamp |
| CN109149973A (en) * | 2018-10-08 | 2019-01-04 | 深圳市力生美半导体股份有限公司 | Constant current output control circuit and its design method |
| CN109149973B (en) * | 2018-10-08 | 2023-12-01 | 深圳市力生美半导体股份有限公司 | Constant current output control circuit and design method thereof |
| CN109976439A (en) * | 2019-04-29 | 2019-07-05 | 苏州市职业大学 | High efficiency can multi-path flow equalizing constant-current source circuit |
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Legal Events
| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130403 Termination date: 20181022 |
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| CF01 | Termination of patent right due to non-payment of annual fee |