For the light adjusting circuit of non-isolated LED drive powerTechnical field
This utility model is related to a kind of light adjusting circuit, and in particular to a kind of light modulation electricity for non-isolated LED drive powerRoad.
Background technology
LED (Light Emitting Diode) is called and does light emitting diode, and it is visible to be that one kind can be converted electrical energy intoThe semiconductor device of the solid-state of light, it directly can be converted into light electricity.The heart of LED is the chip of a quasiconductor, chipOne end be attached on a support, one end is negative pole, and the other end connects the positive pole of power supply, makes whole chip by epoxy encapsulationGet up.Because LED has the advantages that energy-saving and environmental protection, many changes and long service life, it is widely used in indoor and outdoor lighting neckDomain.
Current LED drive power generally needs to have dimming function.Current application be most widely 0～10V light modulation andPWM is dimmed.When dimming to multiple LED, dimmer output 0～10V analogue signals or pwm signal of a concentration, togetherWhen multiple light fixtures for being docked on same circuit dimmed, as shown in Figure 1.
But, when the LED drive power for needing the multiple non-isolated to the direct current supply on the same line is dimmed, each electricityFlow through between the ground in source and exist between electric current, therefore ground potential pressure drop, and first that exports ground and circuit starting point of dimmerThere is suitable voltage drop in driving power supply, so cause the output of dimmer on same current potential with the ground potential of line endVoltage magnitude is varied widely when signal is connected to these power supplys, therefore cannot normally be dimmed.In order to normally dim, need to everyOne single LED drive power configures an independent dimmer, so can significantly increase cost.
Utility model content
This utility model be in order to overcome prior art in when dimming to multiple LED drive powers of direct current supply, due toThe presence of potential difference causes different LED drive power change in voltage big and cannot carry out asking for normal light modulation using a dimmerMultiple LED can be driven by a kind of topic, there is provided light adjusting circuit for non-isolated LED drive power by a dimmerGalvanic electricity source is dimmed.
This utility model provides a kind of light adjusting circuit for non-isolated LED drive power, including power supply, is connected with power supplyAt least two groups non-isolated LED drive powers and with non-isolated LED drive power be connected to non-isolated LED drive power send outThe dimmer of dim signal, non-isolated LED drive power is sent to include that the dim signal for sending to dimmer carries out common mode suppressionThe adjustment circuit of system.
A kind of light adjusting circuit for non-isolated LED drive power described in the utility model, it is preferred that, adjustmentCircuit is Differential input circuit, by first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance,Seven resistance, the 8th resistance and the first operational amplifier composition；The positive input of the first operational amplifier and the 5th resistance, the 6thResistance and the 8th resistance are connected, and dimmer output plus terminal is connected with the 4th resistance and the 5th resistance, the first operational amplifier it is anti-It is connected with second resistance, 3rd resistor and the 7th resistance to input, dimmer exports negative terminal with first resistor and 3rd resistorIt is connected, the outfan of the first operational amplifier is connected with the 7th resistance.The power positive end and second resistance of the first operational amplifierIt is connected with the 6th resistance.The power supply negative terminal of the first operational amplifier is connected with first resistor, the 4th resistance and the 8th resistance.
A kind of light adjusting circuit for non-isolated LED drive power described in the utility model, it is preferred that,
First resistor and the 4th resistor satisfied：
R1=R4；
Second resistance and the 6th resistor satisfied：
R2=R6；
3rd resistor and the 5th resistor satisfied：
R3=R5；
7th resistance and the 8th resistor satisfied：
R7=R8；
Second resistance and 3rd resistor meet：
R2 ＜ V/Vcc × R3；
Wherein：V represents the maximum voltage difference between ground potential；
Vcc represents that operational amplifier controls supply voltage value.
A kind of light adjusting circuit for non-isolated LED drive power described in the utility model, it is preferred that, adjustmentCircuit is couple input circuit, is made up of the 9th resistance, the tenth resistance and photo-coupler, the terminal 1 of photo-coupler with by theNine resistance are connected with dimmer output plus terminal, and the terminal 2 of photo-coupler is connected with dimmer output negative terminal, the terminal of photo-coupler3 are connected with the tenth resistance, and the terminal 4 of photo-coupler is grounded.
A kind of light adjusting circuit for non-isolated LED drive power described in the utility model, it is preferred that, the 9thIt is resistor satisfied：
R9<(Vp-Vd)/In,
Wherein：Vp represents the high potential of the pwm signal of input；
Vd represents the pressure drop of photo-coupler diode；
In represents input current.
This utility model can avoid the generation of line drop due to adjustment circuit is increased in light adjusting circuit so thatNon-isolated LED drive power can be dimmed by a dimmer to multiple LED drive powers.
Description of the drawings
Fig. 1 is LED drive power light adjusting circuit in prior art.
Fig. 2 is a kind of light adjusting circuit for non-isolated LED drive power.
Fig. 3 is for the light adjusting circuit of non-isolated LED drive power in embodiment 1.
Fig. 4 is the circuit diagram of adjustment circuit in embodiment 1.
Fig. 5 is for the light adjusting circuit of non-isolated LED drive power in embodiment 2.
Fig. 6 is the circuit diagram of adjustment circuit in embodiment 2.
Description of the drawings：V1, dimmer input positive terminal；V2, dimmer input negative terminal；U1, the first operational amplifier；R1,One resistance；R2, second resistance；R3,3rd resistor；R4, the 4th resistance；R5, the 5th resistance；R6, the 6th resistance；It is R7, the 7th electricResistance；R8, the 8th resistance；R9, the 9th resistance；R10, the tenth resistance.
Specific embodiment
As shown in Fig. 2 this utility model provides a kind of light adjusting circuit for non-isolated LED drive power, including power supply,Two groups of non-isolated LED drive powers being connected with power supply and it is connected to drive non-isolated LED with non-isolated LED drive powerPower supply sends the dimmer of dim signal, and non-isolated LED drive power includes that the dim signal for sending to dimmer is carried outThe adjustment circuit of common mode inhibition.
Embodiment 1
Differential Input method, as shown in Figure 3 and Figure 5, adjustment circuit is Differential input circuit, by first resistor R1, second electricResistance R2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8 and firstOperational amplifier U1 is constituted；The positive input of the first operational amplifier U1 is electric with the 5th resistance R5, the 6th resistance R6 and the 8thResistance R8 is connected, and dimmer output plus terminal V1 is connected with the 4th resistance R4, the 5th resistance R5 and the 6th resistance R6, the first operation amplifierThe reverse input end of device U1 is connected with second resistance R2,3rd resistor R3 and the 7th resistance R7, dimmer output negative terminal V2 and theOne resistance R1, second resistance R2 are connected with 3rd resistor R3, the outfan of the first operational amplifier U1 and the 7th resistance R27 phasesEven.Wherein：
First resistor R1 and the 4th resistance R4 resistance values meet：
R1=R4；
Second resistance R2 and the 6th resistance R6 resistance values meet：
R2=R6；
3rd resistor R3 and the 5th resistance R5 resistance values meet：
R3=R5；
7th resistance R7 and the 8th resistance value meet：
R7=R8；
Second resistance R2 and 3rd resistor R3 resistance value meet：
R2 ＜ V/Vcc × R3；
Wherein：V represents the maximum voltage difference between ground potential；
Vcc represents that operational amplifier controls supply voltage value.
The present embodiment can be applied to 0～10V light modulations or PWM light modulations.
Embodiment 2
Light-coupled isolation method, as shown in Figure 4 and Figure 6, adjustment circuit is couple input circuit, by the 9th resistance R9, the tenth electricResistance R10 and photo-coupler composition, the terminal 1 of photo-coupler be connected with dimmer output plus terminal V1 by the 9th resistance R9, lightThe terminal 2 of bonder is connected with dimmer output negative terminal V2, and the terminal 3 of photo-coupler is connected with the tenth resistance R10, photo-couplerTerminal 4 be grounded；9th resistance R9 resistance values meet：
R9<(Vp-Vd)/In,
Wherein：Vp represents the high potential of the pwm signal of input；
Vd represents the pressure drop of photo-coupler diode；
In represents input current.
The interface logic and electrical characteristic of dimmer is designed as：
1) dim signal is unloaded short-circuit or permanent when being low, and power supply is exported with rated current；
2) when dim signal perseverance is high, power supply is in no current output state；
3) frequency of dim signal is about 1kHz；
4) dutycycle D (ratio in high potential time and cycle) of dim signal determines output current, and formula is I=(1-D) * In, wherein In are rated current；
5) the light modulation input current of each non-isolated power supply is less than 2mA.
The present embodiment can be applied to PWM light modulations.
It is described above to be merely exemplary for this utility model, and nonrestrictive, those of ordinary skill in the artUnderstand, in the case of the spirit and scope limited without departing from claim, any modification, change or the equivalent shape that can be madeFormula is fallen within the protection domain of utility model.