CN214592072U - Device for controlling LED brightness by using voltage - Google Patents
Device for controlling LED brightness by using voltage Download PDFInfo
- Publication number
- CN214592072U CN214592072U CN202120449955.0U CN202120449955U CN214592072U CN 214592072 U CN214592072 U CN 214592072U CN 202120449955 U CN202120449955 U CN 202120449955U CN 214592072 U CN214592072 U CN 214592072U
- Authority
- CN
- China
- Prior art keywords
- circuit
- led
- voltage
- current
- power supply
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 description 17
- 230000003287 optical effect Effects 0.000 description 14
- 230000003321 amplification Effects 0.000 description 10
- 238000003199 nucleic acid amplification method Methods 0.000 description 10
- 230000002265 prevention Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Landscapes
- Control Of El Displays (AREA)
Abstract
The utility model discloses an utilize device of voltage control LED luminance, it includes control voltageUThe device comprises a generating circuit, a voltage-current converter circuit, a photoelectric coupler circuit, a Darlington amplifying circuit, a high-power LED circuit, a +6V power supply and a +24V power supply. +6V constitutes the control voltage through the resistor R2 and the potentiometer POT connected in sequence and working onceUThe sliding end of the POT is connected with the pin 2 of the N1; voltage-to-current converter circuit N1The LED lamp comprises a light emitting end of N2 and a resistor R1, wherein the output end of N1 is connected with a one-time working place through a light emitting tube of N2 and the resistor R1 in sequence, and a pin 2 of N2 is connected with a pin 3 of N1; the 3 pins of the N2 are connected with the base electrode of the Darlington tube Q through a resistor R3, the light emitting tubes D1-Dn form a high-power LED circuit, and the +24V is connected with a secondary working ground through the D1, the Dn and the C-E electrode of the Darlington tube Q in sequence to provide amplified constant current power supply for the LED group.
Description
Technical Field
The utility model relates to an utilize technique of voltage control LED luminance, this circuit belong to the category of constant current source control LED luminance, nevertheless pass through fortune circuit implementation constant current control by the voltage of linear change.
Background
The method for realizing LED brightness control can be theoretically divided into two methods, one method is to change the current flowing through the LED, the continuous working current of the LED tube is allowed to be about 20 milliamperes, and the brightness of other LEDs is basically proportional to the flowing current except that the red LED has the saturation phenomenon; another method is to use the visual inertia of the human eye to implement the gray scale control by PWM (pulse width modulation), i.e. to periodically change the light pulse width (i.e. duty cycle), so long as the period of this repetitive illumination is sufficiently short (i.e. the refresh frequency is sufficiently high), the human eye does not perceive the luminous pixels as jittering. Since pulse width modulation is more suitable for digital control, almost all LED panels today use pulse width modulation to control gray scale levels, where microcomputers are commonly used to provide LED display content.
The brightness of the LED lamp is basically in direct proportion to the passing current, but the relation of the voltage at the heel end is nonlinear, so that the first method belongs to the constant current source control; the second method uses a constant voltage power supply as a drive, and generally employs a PWM control method when brightness adjustment is to be achieved.
The LED is supplied with power by a constant current power supply, and after the current is constant, the current is not changed no matter how the temperature is changed and the volt-ampere characteristic is shifted to the left! Junction temperature will not cycle viciously!
The transformer in the conventional sense means that the voltage is changed to be high or low, the output voltage is stable and unstable, the LED driving power supply is matched with the power of the LED, and the working power of the LED is required to be stable for the LED for illumination. Since the voltage variation across the LED is small but the current varies steeply with voltage, the power is stabilized by stabilizing the driving current.
If the LED is not driven by constant current, the LED is driven by two conditions: if the LED is driven near the rated power of the LED, the state of exceeding the rated current is easy to occur, so that the service life of the LED is shortened, and the LED is even burnt out quickly; and secondly, the maximum value of the limited current fluctuation is smaller than the rated current, the LED cannot be damaged, but the output light power can change along with the current change.
If the LED does not have a constant current, as mentioned above, the LED tube is easily damaged due to the excess power, and the light output from the LED is unstable. Of course, there are some devices that are dedicated to causing the LEDs to flash, which is not a drawback.
The circuit belongs to the field of controlling the LED brightness by a constant current source, however, the constant current control is realized by linearly changing voltage through an operational amplifier circuit, the constant current further controls the input end (light emitting diode) of a linear photoelectric coupler, the output end of the optical coupler has amplified constant current source output, the output end of the optical coupler further controls a Darlington tube, the Darlington tube works in a direct current amplifier state, and amplified constant current power supply is provided for an LED group.
Disclosure of Invention
The utility model aims to solve the technical problem that a device of LED brightness control simple structure, low in cost, use are reliable is provided, it is different from the technique that adopts pulse width modulation to control LED grey scale.
To achieve the above object, the present invention provides a device for controlling LED brightness by using voltage, which comprises a control circuit for controlling the voltageUThe device comprises a generating circuit, a voltage-current converter circuit, a photoelectric coupler circuit, a Darlington amplifying circuit, a high-power LED circuit, a +6V direct-current power supply and a +24V direct-current power supply. The +6V direct current power supply is connected with a one-time working ground through a resistor R2 and a potentiometer POT in sequence to form the control voltageUGenerating circuit, the sliding terminal of the potentiometer POT outputs the control voltageUThe input end of the operational amplifier N1 is connected with the input end of the operational amplifier; the voltage-current converter circuit consists of an operational amplifier N1, a light emitting end of an optocoupler N2 of the optocoupler circuit and a resistor R1, an output end of the operational amplifier N1 is connected with a primary working place through a light emitting diode of the optocoupler N2 and a resistor R1 in sequence, and a pin 2 of the optocoupler N2 is connected with an inverted input end of the operational amplifier N1; the 3 feet of the optocoupler N2 of the photoelectric coupler circuit are connected with the base electrode of the Darlington amplifying circuit Q through a current limiting resistor R3,the light emitting diodes D1-Dn form the high-power LED circuit, and the +24V direct-current power supply is connected with a secondary working ground through the D1, the Dn and the C-E pole of the Darlington tube Q in sequence.
And 4 pins of the optocoupler N2 of the optocoupler circuit are connected with the +24V direct-current power supply.
Drawings
Fig. 1, 2, 3, 4, and 5 are provided to provide a further understanding of the present invention and form a part of the present application, and fig. 1 is a TL431 based constant current source circuit; fig. 2 is an SJT5301B application principle; FIG. 3 is a principle of linear voltage control of LED brightness based on a constant current source; FIG. 4 is a luminance principle of a linear voltage control LED based on zero current; fig. 5 is an electrical principle for realizing the brightness control of the high-power LED based on constant current.
Detailed Description
1. Single TL431 constant current circuit
Referring to fig. 1, which is a schematic diagram of a constant current using a single TL431, the operation principle, advantages and disadvantages of the circuit are explained as follows:
the principle is as follows: the circuit is very simple, utilizes a reference of 2.495V of 431 for constant current, and also limits the voltage drop on the LED, but the advantages and the disadvantages are obvious.
The advantages are that: simple circuit, few components and low cost, because TL431 has high reference voltage precision, R12，R13As long as the high-precision resistor is adopted, the constant current precision is higher.
The disadvantages are as follows: since TL431 is 2.5V reference, the loss of the constant current sampling circuit is very large, and it is not suitable for power supply with excessive output current.
The circuit has the fatal defect that no load is available, so the circuit is not suitable for being used as an external LED power supply.
The constant current point of this circuit is calculated as: i isD=2.495/（R12//R13），IDFinger pass through D1、D2The current of (2).
Sampling resistor R12，R13Has a power of PR=2.495*2.495/（R13//R13），PRFinger resistance R13//R13The power consumed. For a low-power supply, the loss of the power is considerable, so that the circuit is not recommended to be used for products with current larger than 200 mA.
Application of LED brightness adjusting IC based on PWM
The SJT5301B is a touch dimming IC suitable for adjusting the brightness of LED lamplight, and has dimming modes such as stepless dimming, two-stage dimming, three-stage dimming and the like, wherein the three-stage dimming can be adjusted from high brightness to low brightness and also can be adjusted from low brightness to high brightness, the brightness of the lamplight is randomly set, and the operation is simple and convenient; the unique buzzer reminding function and the standby breath lamp indicating effect make the product have more characteristics. The SJT5301B can achieve the touch dimming function under the isolation of non-conductive materials, and has the advantages of dust prevention, water prevention, scratch prevention, strength, durability, high safety and the like; the sensitivity of the touch induction key can be freely adjusted according to actual needs, the number of peripheral elements is small, and an application circuit is very simple.
The principle of application of SJT5301B is shown in fig. 2, and its functional characteristics are shown in table 1.
Table 1 SJT5301B application function characteristics table
| MODE2 | MODE1 | |
| VSS | VSS | Three-stage dimming from low to high brightness |
| VSS | VDD | Three-stage dimming from high brightness to low brightness |
| VDD | VSS | Continuous dimming |
| VDD | VDD | Two-stage dimming from low brightness to high brightness |
As shown in fig. 2, the dedicated dimming IC belongs to a dimming mode for implementing gray scale control by using a PWM (pulse width modulation) method, the PWM output is a width (Duty) for modulating a high potential, the high potential is turned off (TurnOff) when the width of the high potential is 0%, the high potential is fully turned on (TurnOn) when the width of the high potential is 100%, the adjustment range is 12.5% to 100%, the frequency is about 500Hz, the PWM can be connected to an LED constant current driving IC or directly connected to a MOSFET (N-CHANNEL) driving load, and the power of the driving IC or the MOSFET needs to be calculated by itself.
Principle of 3 voltage control of LED brightness
As known above, the method of dimming the light emitting diode by changing the duty ratio of the waveform is the most common dimming method for the light emitting diode, and when dimming the light emitting diode by this method, the brightness of the light emitting diode can be changed by only adjusting the duty ratio of the PWM generator. The PWM light modulation circuit consists of a PWM signal generator and a driving circuit, wherein the PWM signal generator can be generated by a CMOS gate circuit such as CD4011 or an 8-pin singlechip such as ATtiny13, and the driving circuit can be formed by a triode or a special driving IC.
Therefore, the control method firstly needs a PWM signal generator to generate a PWM signal, the circuit structure is slightly complex, a circuit for linearly controlling the brightness of the LED by voltage can be designed, the circuit can control the brightness of the LED by constant current, and the control method is different from the constant voltage control of the PWM control, and is the control method for controlling the optimal brightness of the LED.
It is often desirable to have the brightness of the LED vary in direct proportion to the magnitude of the dc control voltage, and such control voltage is sometimes lower than the forward voltage drop of the LED.
LED brightness control realized by voltage-current converter based on active rectifying circuit
The brightness of an LED is proportional to the current through it, and therefore, the circuit is required to be a voltage/current converter capable of providing a current through the LED independent of forward voltage drop, which can be satisfied with a conventional operational amplifier active rectifying circuit.
Such a voltage/current converter is shown in fig. 3, N1Is an ideal operational amplifier, a light emitting diode D1Representing a series-connected set of luminous tubes, D2To protect the diode.
Characteristics of ideal operational amplifier
An ideal operational amplifier must have the following characteristics:
infinite input impedance (Z)in= ∞): an ideal operational amplifier input does not allow any current to flow, i.e. the input impedance is infinite, referred to as virtual break.
Output impedance (Z) approaching zeroout= 0): the output of an ideal operational amplifier is a perfect voltage source, and the output voltage of the amplifier is constant regardless of the variation of the current flowing to the load of the amplifier, that is, the output impedance is zero.
Infinite large open loop gain (A)d= ∞): an important property of an ideal operational amplifier is that in an open-loop state, a differential signal at an input end has infinite voltage gain, which makes the operational amplifier very suitable for being added with a negative feedback configuration in practical application, and this characteristic may be referred to as "virtual short".
Infinite common mode rejection ratio (CMRR = ∞): ideal operational amplifier only for V+And V−The difference between the voltages at the two terminals being responsive, i.e. amplifying only V+ − V −The above-mentioned composition. The same part (i.e. common mode signal) for both input signals will be completely ignored.
Bandwidth of infinity: an ideal operational amplifier will amplify an input signal at any frequency with the same differential gain, and will not change as the frequency of the signal changes.
In the design, two characteristics of 'virtual break' and 'virtual short' of the ideal operational amplifier are used, the virtual break is that the injection current of the ideal operational amplifier is '0', and the virtual short is that two input ends of the same phase and the opposite phase of the ideal operational amplifier are in virtual short circuit.
Linear voltage control LED brightness based on constant current source
The circuit for controlling the brightness of LED based on the linear voltage of constant current source is shown in FIG. 3, because of the LED D1Connected between the output end and the inverting input end of the operational amplifier to form a negative feedback, so that the operational amplifier N1Operating in a linear amplifier state.
If a gradually increasing positive voltage U is applied to the operational amplifier N shown in FIG. 31The voltage of the operational amplifier output end gradually swings towards the reference voltage '0' until the light emitting diode D1Until power is on, the operational amplifier N is based on the 'virtual short' characteristic of the ideal operational amplifier1The inverting input terminal of (2) is a virtual ground point, thus passing through a current limiting resistor R1Current (i.e. through the led D)1Current of) IR1=U/R1。
The current only corresponds to the input voltage U and the current limiting resistor R1So that the input voltage U and the resistance R are ensured1By D1Can be regarded as a constant current source.
In the absence of an input signal (U = 0), the bias of the operational amplifier may cause the output voltage to swing towards a positive voltage and exceed the reverse breakdown voltage of the led and damage the led, thus switching the diode D2The maximum positive bias voltage may be limited to + 0.6V.
If the input signal U is a negative voltage, D is only needed1、D2The polarity of (2) can be reversed.
It should be noted that: in fig. 3, the input voltage U must supply the led D1All current required, andand a light emitting diode D1The representative light emitting tubes must be used in series, if the light emitting tubes are used in parallel, because of IR1Is a constant current source, and the original working current of the LED is 1/2IR1(if D1Representing two light emitting tubes), if one of the two LEDs is open-circuited, the total operating current I isR1All over the undamaged LED, which will soon also be damaged.
If D is1If the representative luminotrons are used in series, if one LED is damaged by short circuit, the working current is still IR1The LED which is not damaged can still work normally; if one of the two LEDs is damaged due to open circuit, the two LEDs lose working current but cannot damage the other LED, and the work is recovered to be normal as long as the damaged LED is replaced.
3.1.3 Linear Voltage control based on zero Current LED Brightness
The circuit for controlling LED brightness by voltage in FIG. 3 is further upgraded to the circuit for controlling LED brightness shown in FIG. 4, in which the input voltage (control voltage) is not from N in the circuit of FIG. 41Is instead input from the inverting terminal of (1), but from N1The non-inverting terminal of (1).
FIG. 4 is a circuit with high input impedance, based on the "virtual break" characteristic of an ideal operational amplifier, the operational amplifier N1The non-inverting and inverting inputs of the circuit draw no current, so the circuit draws virtually no current from the input voltage U (control voltage).
A gradually increasing positive input voltage U is applied to a linear operational amplifier N1Non-inverting input of, N1Until it equals the voltage at the inverting input, based on the "virtual short" characteristic of the operational amplifier, there is a current IR1=U/R1Through a resistance R1Because this current is from the operational amplifier N1Is generated at the output end of (1), and thus also passes through the luminous tube D1The LED emits light.
Similar to fig. 3, as long as the input voltage U and the resistance R are ensured1By D1The current can still be regarded as a constant current source, a luminous tube D1The representative LED must alsoConnected in series, and connected in parallel with a potential for damage.
In FIG. 4, the resistor R1Can be determined in such a way that R1=UMAX / IMAXWherein U isMAXIs the required maximum input voltage, IMAXIs the required maximum current of the LED.
As for the operational amplifier N1Any operational amplifier capable of providing such a current may be used. High speed of Texas instruments Inc. ((R))>50 MHz), high output current operational amplifiers can provide high output current while being able to drive low impedance loads with excellent linearity, such as BB OPA551 operational amplifiers.
3.2 high-power LED brightness control based on constant current
It can be seen that the circuits for controlling the brightness of the LED based on the constant current of fig. 3 and 4 can only be applied to the linear control of the brightness of the low-power LED or the small number of LEDs, because the current for driving the LED is provided by the operational amplifier, and the operational amplifier is good at small signal amplification (or processing) rather than power amplification, so the driving capability is limited.
In order to realize the driving of the high-power LED, a constant current I is requiredR1The value is subjected to current linear amplification, the Darlington tube can be set to work in a linear amplification state, and the base current of the base electrode of the Darlington tube is linearly amplified by beta1β2The collector of the Darlington tube outputs amplified current to drive the high-power LED, and the current IR1As the primary current of the photoelectric coupler, the secondary current can be used as the base current of the Darlington tube, and the detailed circuit is shown in figure 5.
It can be seen that the means for controlling the brightness of the light emitting diode by means of a voltage comprises controlling the voltageUThe device comprises a generating circuit, a voltage-current converter circuit, a photoelectric coupler circuit, a Darlington amplifying circuit, a high-power LED circuit, a +6V direct-current power supply and a +24V direct-current power supply.
Both the conversion of current and the amplification of current need to work in a linear amplification state, so in the above module circuit, the selection of the photocoupler is very important.
Current transfer ratio of photoelectric coupler CTR
The current transmission ratio of the optical coupler refers to the ratio of the secondary side current of the optical coupler to the primary side current of the optical coupler. Namely: the primary side flows a certain current, the secondary side flows the maximum value of the current, and the ratio of the maximum value of the secondary side current under the condition of the primary side current to the primary side current is CTR. When the output voltage is kept constant, it is equal to the secondary side DC output current ICAnd primary side direct current input current IFPercentage of (c). When the current amplification factor hFE of the receiving tube is constant, it is equal to the output current IC and the input current IFThe ratio is usually expressed as a percentage. There is the formula: CTR = IC/IF × 100%
The range of CTR is 20-30% (such as 4N 35), PC817 is 80-160%, and Darlington type optical coupler (such as 4N 30) is 100-500%. This means that to obtain the same output current, the latter requires a smaller input current.
Thus, the CTR parameter has some similarity to the hFE of the transistor, the CTR-I of a conventional optocouplerFThe characteristic curve is non-linear at IFThe nonlinear distortion is particularly severe when small, and therefore it is not suitable for transmitting analog signals, the CTR-I of a linear optical couplerFThe characteristic curve has good linearity, and especially when transmitting small signals, the transmission ratio of alternating current (delta CTR ═ delta IC/delta I)F) Very close to the dc current transfer ratio CTR value.
Therefore, the optical coupler feedback type switching power supply is suitable for transmitting analog voltage or current signals, and can enable the output and the input to be in a linear relation, which is an important characteristic, when the optical coupler feedback type switching power supply is designed, the model and the parameters of the linear optical coupler must be correctly selected, and the selection principle is as follows:
(1) the allowable range of the Current Transfer Ratio (CTR) of the optocoupler is 50% to 200%. This is because when CTR < 50%, the LED in the optocoupler requires a large operating current (I)FMore than 5.0mA) to normally control the duty ratio of the monolithic switching power supply IC, which increases the power consumption of the optocoupler. If CTR is more than 200%, when the starting circuit or the load is suddenly changed, the single-chip switching power supply can be triggered by mistake to influence normal outputAnd (6) discharging.
(2) It is recommended to use a linear optical coupler, which is characterized in that the CTR value can be linearly adjusted within a certain range.
The optocoupler of FIG. 5 selects TLP521, which is a non-Darlington type optocoupler, which may be a Darlington type linear optocoupler if desired.
3.2.2 brief introduction to the principle of constant Current based high Power LED Brightness control
The high-power LED brightness control circuit shown in FIG. 5 has a simple working principle, and inputs a control signal U and an ideal operational amplifier N1Resistance R1Optocoupler N2The primary side of the primary side forms a voltage-current linear converter circuit, and 12V power is supplied through a potentiometer P1Grounding, outputting voltage control signal from the sliding end of the potentiometer, and if the control signal U and the resistor R are adopted1The output of the converter can be used as a constant current source after being kept stable.
Optical coupler N2The primary current is through a resistor R1Current of (I)R1，N2Is a linear optical coupler, the CTR =150, the Darlington transistor Q only needs to ensure the collector voltage and the base voltage VBDifference of difference VBC>0 and its B-E junction is forward biased, the transistor Q operates in a linear amplification state.
Current amplification factor beta = beta of Darlington tube1β2Therefore, the driving current I of the high-power LED is approximately equal to:
4 notes on items
In order to ensure constant current power supply of a high-power LED, an optical coupler must be selected as a linear photoelectric coupler, and a Darlington tube must work in a linear amplification state.
In the actual operation process, the working current of the high-power LED (or a plurality of LEDs connected in series) is firstly known by looking up data, and a slide wire potentiometer (D in the circuit shown in FIG. 5)1~DNPosition) instead of an LED, an ammeter is connected in series to the LED circuit, and a sliding potentiometer is adjustedAnd the POT changes the control voltage U, so that the reading of the ammeter is just equal to the working current of the LED, the slide wire potentiometer and the ammeter are removed, and the LED is connected to the position vacated by the circuit.
The design ingeniously utilizes the characteristics of 'virtual short' and 'virtual break' of the operational amplifier to form a voltage-current converter circuit, the converter can be regarded as a constant current source as long as the stability of control voltage and current-limiting resistance is guaranteed, and the constant current source is most suitable for supplying power to the LED.
Claims (2)
1. An apparatus for controlling brightness of an LED using a voltage, comprising: the device comprises a control voltageUThe control circuit comprises a generating circuit, a voltage-current converter circuit, a photoelectric coupler circuit, a Darlington amplifying circuit, an LED circuit, a +6V direct current power supply and a +24V direct current power supply, wherein the +6V direct current power supply is connected with a potentiometer POT through a resistor R2 in sequence to form the control voltage in a one-time working modeUGenerating circuit, the sliding terminal of the potentiometer POT outputs the control voltageUThe input end of the operational amplifier N1 is connected with the input end of the operational amplifier; the voltage-current converter circuit consists of an operational amplifier N1, a light emitting end of an optocoupler N2 of the optocoupler circuit and a resistor R1, an output end of the operational amplifier N1 is connected with a primary working place through a light emitting diode of the optocoupler N2 and a resistor R1 in sequence, and a pin 2 of the optocoupler N2 is connected with an inverted input end of the operational amplifier N1; the 3 feet of the optocoupler N2 of the photoelectric coupler circuit are connected with the base electrode of the Darlington amplifying circuit Q through a current limiting resistor R3, light emitting diodes D1-Dn form the LED circuit, and the +24V direct-current power supply is connected with a secondary working ground through D1, Dn and the C-E pole of the Darlington tube Q in sequence.
2. The device for controlling the brightness of the LED by using the voltage as claimed in claim 1, wherein: and 4 pins of the optocoupler N2 of the optocoupler circuit are connected with the +24V direct-current power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120449955.0U CN214592072U (en) | 2021-03-02 | 2021-03-02 | Device for controlling LED brightness by using voltage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120449955.0U CN214592072U (en) | 2021-03-02 | 2021-03-02 | Device for controlling LED brightness by using voltage |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214592072U true CN214592072U (en) | 2021-11-02 |
Family
ID=78352365
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120449955.0U Expired - Fee Related CN214592072U (en) | 2021-03-02 | 2021-03-02 | Device for controlling LED brightness by using voltage |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214592072U (en) |
-
2021
- 2021-03-02 CN CN202120449955.0U patent/CN214592072U/en not_active Expired - Fee Related
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100771780B1 (en) | Led driving apparatus having fuction of over-voltage protection and duty control | |
| TWI423731B (en) | Light-emitting diode (led) current balance circuit | |
| Narra et al. | An effective LED dimming approach | |
| CN101572984B (en) | Image ratio constant flow source circuit driving multipath light emitting diode | |
| TWI486098B (en) | Control circuit of led driver and offline control circuit thereof | |
| CN202855272U (en) | LCD backlight constant current drive circuit based on operational amplifiernegative feedback circuit | |
| CN101500358B (en) | Output current compensation circuit of LED driving circuit | |
| US11272588B2 (en) | Dimming signal processing circuit having multiple functions | |
| CN107548202B (en) | Voltage current transformating circuit and load driving circuits | |
| CN103037597B (en) | Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system | |
| CN101106850A (en) | LED drive circuit | |
| CN201197211Y (en) | Output current compensation circuit of LED driving circuit | |
| KR101128680B1 (en) | Ac direct coupled led lighting device | |
| CN101848582A (en) | Controller for led driver and led driver | |
| CN2862144Y (en) | Constant-current source apparatus | |
| TWI510133B (en) | Digital pulse wave drive device for stabilizing the optical power of light emitting diodes | |
| CN201426197Y (en) | Mirror image proportion constant-current source circuit for driving multi-way LEDs | |
| CN115149928A (en) | Voltage-insensitive high-precision oscillator circuit of process thermometer | |
| CN214592072U (en) | Device for controlling LED brightness by using voltage | |
| TWI593223B (en) | Power conversion apparatus | |
| US7550933B1 (en) | Offline control circuit of LED driver to control the maximum voltage and the maximum current of LEDs | |
| CN201910961U (en) | Light source adjusting device of colored light-emitting diode | |
| CN212229004U (en) | Optical coupling isolation detection circuit with low power consumption and wide voltage | |
| CN112333884A (en) | Driving circuit for plant illumination | |
| US7078942B2 (en) | Driving apparatus for generating a driving current using PWM |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20211102 |