CN109302777B - LED dimming device and dimming system - Google Patents

LED dimming device and dimming system Download PDF

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Publication number
CN109302777B
CN109302777B CN201811490642.9A CN201811490642A CN109302777B CN 109302777 B CN109302777 B CN 109302777B CN 201811490642 A CN201811490642 A CN 201811490642A CN 109302777 B CN109302777 B CN 109302777B
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switch
circuit
input
inverter
output
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CN109302777A (en
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黄赖长
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Shenzhen Dexin Chuangwei Electronics Co ltd
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Shenzhen Dexin Chuangwei Electronics Co ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The invention discloses an LED dimming device and a dimming system, wherein the LED dimming device comprises a power supply circuit, an LED lamp group and a driving circuit, the driving circuit comprises a voltage drop circuit, a reference voltage circuit, a control circuit, a first switch, a second switch, a third switch and a first current source, the control circuit receives PWM signals, outputs first logic signals according to the received PWM signals to control the on or off of the first switch, simultaneously outputs second logic signals to control the off or on of the second switch, the first switch and the second switch are controlled in forward and reverse directions, the third switch is conducted when receiving a preset reference voltage value, and when the first switch is conducted, the output current value is changed according to the first logic signals, and when the second switch is conducted, the first current source outputs a pull-up voltage to the third switch to accelerate the voltage rising speed of a controlled end of the third switch. The invention can solve the problem of slower rise of the switching voltage of the LED dimming device during PWM dimming in the prior art.

Description

LED dimming device and dimming system
Technical Field
The invention relates to the field of intelligent LED dimming, in particular to an LED dimming device and a dimming system.
Background
The LED (Light-Emitting Diode) is widely used in the prior society, the energy consumption of the white Light LED is only 1/10 of that of an incandescent lamp, the white Light LED has an ultra-long service life, the specific service time can reach more than 50000 hours, the white Light LED is more than 50 times that of a traditional tungsten filament lamp, and the LED lamp does not contain heavy metal elements such as lead or mercury and the like and has no heavy metal pollution to the environment. For reasons of green, environment-friendly, energy-saving, long service life and the like, the LED lamp is deeply favored by consumers, and the use of the LED lamp for replacing the traditional incandescent lamp and the energy-saving lamp is encouraged by the nation.
The driving chip design of the LED lamp is mainly divided into two major types of switching Power supply driving and linear constant current driving, the switching Power supply has the advantages of relatively good linear adjustment rate and load adjustment rate, so the efficiency is high, the switching Power supply has the disadvantages of complex system, large volume and relatively high manufacturing cost, the linear constant current driving has the disadvantages of limited linear adjustment rate and load adjustment rate, the efficiency is low compared with the switching Power supply driving, the switching Power supply has the advantages of no need of using an inductor, relatively high PF (Power Factor) value, no EMI (Electromagnetic Interference ) problem, and the system has simple application and low cost. Today, LED lighting in China is cheaper and cheaper, and in the market of pursuing cost, linear constant current driving schemes are favored and accepted by more and more LED lamp manufacturers.
At present, domestic linear constant current driving is mainly divided into dimming type and non-dimming type, the dimming type mainly uses a silicon controlled rectifier for dimming, but along with the development of intelligent illumination, the LED linear constant current driving needs to be matched with Bluetooth, wifi and other communication modules for use, so that a pulse width adjusting function is added in the linear constant current driving to adjust brightness and color temperature, and the existing dimming depth is generally 5% -7%.
Disclosure of Invention
The invention mainly aims to provide an LED dimming device, which aims to solve the technical problem that the switching voltage of the LED dimming device rises slowly during PWM dimming in the prior art.
In order to achieve the above object, the present invention provides an LED dimming device, including a power supply circuit, an LED lamp group, and a driving circuit, where the driving circuit includes a voltage drop circuit, a reference voltage circuit, a control circuit, a first switch, a second switch, a third switch, and a first current source;
the power supply circuit is used for providing working power supply for the LED lamp group;
the voltage drop circuit is used for providing working voltages for the control circuit, the reference voltage circuit and the first current source;
the reference voltage circuit is used for outputting a preset reference voltage;
the control circuit is used for receiving the PWM signal, outputting a first logic signal to control the on or off of the first switch according to the received PWM signal, and outputting a second logic signal to control the off or on of the second switch, wherein the first switch and the second switch are controlled in forward and reverse directions;
the third switch is used for being conducted when the preset reference voltage value is received, and when the first switch is conducted, the output current value is changed according to the first logic signal;
the first current source is configured to output a pull-up voltage to the third switch when the second switch is turned on, so as to accelerate a voltage rising speed of a controlled terminal of the third switch.
Optionally, the control circuit includes a power input end, a control signal input end, a first output end and a second output end, the output end of the power circuit is connected with the input end of the LED lamp group, the output end of the LED lamp group, the input end of the voltage drop circuit and the first end of the third switch are interconnected, a connection node of the voltage drop circuit and the third switch is the input end of the driving circuit, and the output end of the voltage drop circuit, the input end of the reference voltage circuit, the power input end of the control circuit and the input end of the first current source are interconnected; the control signal input end of the control circuit is connected with external control equipment, the first output end of the control circuit is connected with the controlled end of the first switch, and the second output end of the control circuit is connected with the controlled end of the second switch; the output end of the reference voltage circuit, the first end of the first switch, the first end of the second switch and the controlled end of the third switch are interconnected, and the second end of the first switch is the grounding end of the driving circuit; the second end of the second switch is connected with the output end of the first current source; the second end of the third switch is the output end of the driving circuit.
Optionally, the driving circuit is integrated on a driving chip.
Optionally, the LED dimming device further includes a grounding resistor, an output end of the driving circuit is connected with a first end of the grounding resistor, and a grounding end of the driving circuit and a second end of the grounding resistor are grounded.
Optionally, the voltage drop circuit includes a field effect tube and an internal power supply generator, a gate of the field effect tube is grounded, a drain of the field effect tube is an input end of the voltage drop circuit, a source of the field effect tube is connected with an input end of the internal power supply generator, and an output end of the internal power supply generator is an output end of the voltage drop circuit.
Optionally, the reference voltage circuit includes a bandgap reference, a first operational amplifier and a second current source, where an input end of the bandgap reference and an input end of the second current source are connected, a connection node of the bandgap reference and the second current source is an input end of the reference voltage circuit, and an output end of the bandgap reference is connected with a positive input end of the first operational amplifier; the output end of the second current source is connected with the power end of the first operational amplifier, the reverse input end of the first operational amplifier is connected with the second end of the third switch, and the output end of the first operational amplifier is the output end of the reference voltage circuit.
Optionally, the control circuit includes a schmitt trigger, a first inverter, a second inverter, a third inverter, a fourth inverter, a fifth inverter, a sixth inverter, a third current source, a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a first capacitor, and a nand gate, an input end of the schmitt trigger is a control signal input end of the control circuit, and an output end of the schmitt trigger is connected with an input end of the first inverter; the output end of the first inverter is connected with the input end of the second inverter, and the output end of the second inverter is connected with the input end of the third inverter; the output end of the third inverter, the input end of the sixth inverter, the first input end of the NAND gate, the grid electrode of the first MOS tube and the grid electrode of the second MOS tube are interconnected; the source of the first MOS tube is the power supply input end of the control circuit, and the drain electrode of the first MOS tube, the drain electrode of the second MOS tube, the first end of the first capacitor and the input end of the fourth inverter are interconnected; the source electrode of the second MOS tube is connected with the drain electrode of the third MOS tube, the source electrode of the third MOS tube, the substrate of the second MOS tube, the source electrode of the fourth MOS tube and the second end of the first capacitor are all grounded, and the grid electrode of the third MOS tube, the grid electrode of the fourth MOS tube, the drain electrode of the fourth MOS tube and the output end of the third current source are connected; the input end of the third current source is connected with the output end of the voltage drop circuit; the output end of the sixth inverter is a first output end of the control circuit; the output end of the fourth inverter is connected with the input end of the fifth inverter, the output end of the fifth inverter is connected with the second input end of the NAND gate, and the output end of the NAND gate is the second output end of the control circuit.
Optionally, the first switch and the third switch are N-MOS transistors, and the second switch is a P-MOS transistor.
In order to achieve the above object, the present invention further provides a dimming system, which includes a plurality of LED dimming devices as described above, and a plurality of the LED dimming devices are disposed in parallel.
Optionally, the input ends of the control circuits of the plurality of LED dimming devices are connected with one or more external control devices, and the control circuits of the plurality of LED dimming devices receive the same/different PWM signals.
The invention provides an LED dimming device which comprises a power supply circuit, an LED lamp group and a driving circuit, wherein the driving circuit comprises a voltage drop circuit, a reference voltage circuit, a control circuit, a first switch, a second switch, a third switch and a first current source. The power supply circuit provides working power for the LED lamp group, and the voltage drop circuit provides working voltage for the control circuit, the reference voltage circuit and the first current source. The reference voltage circuit outputs a preset reference voltage. The control circuit outputs a first logic signal to control the first switch to be turned on or off according to the received PWM signal, and outputs a second logic signal to control the second switch to be turned off or on at the same time, wherein the first switch and the second switch are controlled in forward and reverse directions, namely when the first switch is turned on, the second switch is turned off, or when the first switch is turned off, the second switch is turned on. And then, the third switch is turned on when receiving the preset reference voltage value, and at the moment, the LED dimming device is in a constant current control state. And when the first switch is turned on, changing the output current value according to the first logic signal, thereby enabling PWM dimming. The first current source is used for outputting a pull-up voltage to the third switch when the second switch is conducted, so that the voltage rising speed of the controlled end of the third switch is increased, the problem that the switch voltage of the LED dimming device is slowly increased when PWM dimming is performed can be solved, the switch voltage rising speed of the LED dimming device when PWM dimming is performed is increased, the dimming depth of the LED dimming device is increased, and intelligent dimming is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic block diagram of an LED dimmer according to the present invention;
fig. 2 is a schematic circuit diagram of an LED dimmer according to the present invention;
FIG. 3 is a schematic diagram showing a comparison of PWM signals, first logic signals and second logic signals in an embodiment of an LED dimming device according to the present invention;
FIG. 4 is a schematic diagram illustrating the effect of increasing the boost voltage in an embodiment of the LED dimming device of the present invention;
fig. 5 is a circuit schematic diagram of a control circuit of the LED dimmer according to the present invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, the description of "first," "second," etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
The invention provides an LED dimming device, which aims to solve the problem that the switching voltage of an LED dimming device rises slowly during the existing PWM dimming. The LED control device can be applied to the intelligent control LED fields such as intelligent remote control, human body induction, sound control and the like.
As shown in fig. 1 and 3, an LED dimming device includes a power supply circuit 101, an LED lamp group 102, and a driving circuit 103, where the driving circuit 103 includes a voltage drop circuit 1031, a reference voltage circuit 1032, a control circuit 1033, a first switch 1036, a second switch 1035, a third switch 1037, and a first current source 1034. The control circuit 1033 includes a power input end, a control signal input end, a first output end and a second output end, the output end of the power circuit 101 is connected with the input end of the LED lamp set 102, the output end of the LED lamp set 102, the input end of the voltage drop circuit 1031 and the first end of the third switch 1037 are interconnected, the connection node of the voltage drop circuit 1031 and the third switch 1037 is the input end IN of the driving circuit 103, and the output end of the voltage drop circuit 1031, the input end of the reference voltage circuit 1032, the power input end of the control circuit 1033 and the input end of the first current source 1034 are interconnected. The control signal input terminal of the control circuit 1033 is connected to an external control device, the first output terminal of the control circuit 1033 is connected to the controlled terminal of the first switch 1036, and the second output terminal of the control circuit 1033 is connected to the controlled terminal of the second switch 1035. The output terminal of the reference voltage circuit 1032, the first terminal of the first switch 1036, the first terminal of the second switch 1035 and the controlled terminal of the third switch 1037 are interconnected, and the second terminal of the first switch 1036 is the ground terminal GND of the driving circuit 103. A second terminal of the second switch 1035 is connected to an output terminal of the first current source 1034; the second terminal of the third switch 1037 is the output terminal ISET of the driving circuit 103.
The power supply circuit 101 provides a working power supply for the LED lamp set 102, and the voltage drop circuit 1031 provides a working voltage for the control circuit 1033, the reference voltage circuit 1032 and the first current source 1034, where the working voltage is a voltage obtained by the working power supply flowing through the LED lamp set 102 and then being dropped by the voltage drop circuit 1031. Meanwhile, the reference voltage circuit 1032 outputs a preset reference voltage, the control circuit 1033 outputs a first logic signal DIMN according to the received PWM signal to control the first switch 1036 to be turned on or off, and outputs a second logic signal DIMP to control the second switch 1035 to be turned off or on, where the first switch 1036 and the second switch 1035 are controlled in forward and reverse directions, that is, when the first switch 1036 is turned on, the second switch 1035 is turned off, or when the first switch 1036 is turned off, the second switch 1035 is turned on. The third switch 1037 may be turned on when a preset reference voltage value is received, and the LED dimming device is in a constant current control state. When the first switch 1036 is turned on, the output current value is changed according to the first logic signal DIMN, and at this time, the third switch 1037 can adjust the output current value according to the change of the PWM signal, that is, PWM dimming is performed on the LED lamp set 102. Finally, when the second switch 1035 is turned on, the first current source 1034 outputs a pull-up voltage to the third switch 1037, so as to increase the voltage rising speed of the controlled end of the third switch 1037, increase the duty ratio of the current value output by the corresponding third switch 1037, further deepen the dimming depth of the LED dimming device, and according to experimental statistics, the dimming depth can be increased from the existing 5% -7% to 1%.
Optionally, the control circuit 1033 includes a logic controller 10331.
Alternatively, as shown in fig. 2, the driving circuit 103 is integrated on the driving chip.
The driving circuit 103 is integrated with the driving chip, so that the size can be reduced, the stability of the circuit is increased, the circuit can be assembled after being produced independently, the production is convenient, the transportation and the selling are convenient, the autonomy of a user can be improved, a plurality of driving chips can be selected according to the requirement, and a new LED dimming device can be constructed based on the driving chips, and the LED dimming device is not limited to the LED dimming device in the embodiment.
Optionally, the LED dimming device further includes a ground resistor R1, the output terminal ISET of the driving circuit 103 is connected to the first terminal of the ground resistor R1, and the ground terminal GND of the driving circuit 103 and the second terminal of the ground resistor R1 are grounded.
The grounding resistor R1 can provide a voltage drop to the third switch 1037, so that the third switch 1037 is not directly grounded, and the third switch 1037 can be ensured to work normally.
Optionally, the voltage drop circuit 1031 includes a field effect transistor J1 and an internal power supply generator 10311, the gate of the field effect transistor J1 is grounded, the drain of the field effect transistor J1 is an input terminal of the voltage drop circuit 1031, the source of the field effect transistor J1 is connected to the input terminal of the internal power supply generator 10311, and the output terminal of the internal power supply generator 10311 is an output terminal of the voltage drop circuit 1031.
The field effect tube J1 with proper size is selected, so that the voltage input by the field effect tube J1 is ensured to be definitely larger than the cut-off voltage of the field effect tube J1, therefore, the field effect tube J1 is disconnected after rising to the cut-off voltage and then disconnected after outputting the cut-off voltage after being conducted, the operation is repeated, the voltage output to the internal power supply generator 10311 is ensured to be a smaller constant voltage value, the voltage reducing effect is achieved, and then a constant working voltage is provided for the subsequent corresponding circuit, so that the whole circuit has stable working voltage to maintain operation.
Optionally, the reference voltage circuit 1032 includes a bandgap reference 10321, a first operational amplifier OP and a second current source IB2, an input end of the bandgap reference 10321 and an input end of the second current source IB2 are connected, a connection node of the bandgap reference 10321 and the second current source IB2 is an input end of the reference voltage circuit 1032, and an output end of the bandgap reference 10321 is connected with a positive input end of the first operational amplifier OP; the output terminal of the second current source IB2 is connected to the power supply terminal of the first operational amplifier OP, the inverting input terminal of the first operational amplifier OP is connected to the second terminal of the third switch 1037, and the output terminal of the first operational amplifier OP is the output terminal of the reference voltage circuit 1032.
The bandgap reference device 10321 provides a reference voltage which does not change with temperature for the first operational amplifier OP, the second current source IB2 provides an operating current for the first operational amplifier OP, and the inverting input terminal of the first operational amplifier OP is connected to the voltage output by the second terminal of the third switch 1037, so as to form a voltage follower, so that the voltage of the second terminal of the third switch 1037 is consistent with the voltage output by the first operational amplifier OP, and the accuracy of the PWM signal for adjusting the voltage of the LED lamp set 102 can be ensured. In addition, the first operational amplifier OP, the LED lamp set 102, the third switch 1037 and the ground resistor R1 form a constant current loop, and at this time, due to the pull-up current provided by the first current source 1034, the Phase Margin (PM) of the constant current loop is greatly improved, which is also called as a phase margin, and is an important index in circuit design, and is mainly used for measuring the stability of the negative feedback system and predicting the overshoot of the step response of the closed loop system, so that the performance of the LED dimming device is more stable.
Optionally, as shown in fig. 5, the control circuit 1033 includes a schmitt trigger X1, a first inverter N1, a second inverter N2, a third inverter N3, a fourth inverter N4, a fifth inverter N5, a sixth inverter N6, a third current source IB3, a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a fourth MOS transistor Q4, a first capacitor C1 and a nand gate NOR, wherein an input end of the schmitt trigger X1 is a control signal input end of the control circuit 1033, and an output end of the schmitt trigger X1 is connected with an input end of the first inverter N1; the output end of the first inverter N1 is connected with the input end of the second inverter N2, and the output end of the second inverter N2 is connected with the input end of the third inverter N3; the output end of the third inverter N3, the input end of the sixth inverter N6, the first input end of the NAND gate NOR, the grid electrode of the first MOS tube Q1 and the grid electrode of the second MOS tube Q2 are interconnected; the source electrode of the first MOS transistor Q1 is a power input end of the control circuit 1033, and the drain electrode of the first MOS transistor Q1, the drain electrode of the second MOS transistor Q2, the first end of the first capacitor C1 and the input end of the fourth inverter N4 are connected with each other; the source electrode of the second MOS tube Q2 is connected with the drain electrode of the third MOS tube Q3, the source electrode of the third MOS tube Q3, the substrate of the second MOS tube Q2, the source electrode of the fourth MOS tube Q4 and the second end of the first capacitor C1 are all grounded, and the grid electrode of the third MOS tube Q3, the grid electrode of the fourth MOS tube Q4, the drain electrode of the fourth MOS tube Q4 and the output end of the third current source IB3 are connected; the input end of the third current source IB3 is connected to the output end of the voltage drop circuit 1031; the output terminal of the sixth inverter N6 is the first output terminal of the control circuit 1033; the output end of the fourth inverter is connected with the input end of the fifth inverter, the output end of the fifth inverter is connected with the second input end of the NAND gate NOR, and the output end of the NAND gate NOR is the second output end of the control circuit 1033.
The PWM signal performs waveform sorting anti-interference processing through the schmitt trigger X1, and the third current source IB3, the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, the fourth MOS transistor Q4, and the first capacitor C1 jointly generate a delay circuit, where the signal a output by the third inverter N3 and the signal B output by the fifth inverter N5 generate the second logic signal DIMP through a nand gate NOR. The second logic signal DIMP may pull up the current when the first logic signal DIMN signal is on a falling edge. The output current is pulled up rapidly, and it is noted that the pulse width of the second logic signal DIMP cannot be too large or too small, which may cause a large overshoot of the current, and too small may reduce the dimming depth. So here can be flexibly set as required.
Optionally, the first switch 1036 and the third switch 1037 are N-MOS transistors, and the second switch 1035 is a P-MOS transistor.
Because the input capacitance of the third switch 1037 exists, the gate voltage of the third switch 1037 rises slowly, the second logic signal DIMP is a driving signal of the second switch 1035, and the second switch 1035 mainly pulls up the gate voltage of the third switch 1037 as soon as possible after the falling edge of the first logic signal DIMN arrives. So that the output current coincides as much as possible with the switching speed of the PWM signal. The second current source IB2 provides a bias current for the first operational amplifier OP, and the first current source 1034 pulls up a reference current for the gate voltage of the third switch 1037, and improves the phase margin of the loop, so that the system loop is more stable. It is noted that the first switch 1036 and the third switch 1037 may be P-MOS transistors, and the corresponding second switch 1035 is an N-MOS transistor. Or the first switch 1036, the third switch 1037, and the second switch 1035 may be transistors. The specific principle refers to the above embodiments and is not described herein.
The principle of the invention is described below with reference to fig. 1, 2, 3, 4:
the pinch-off voltage through field effect transistor J1 lowers the voltage. The reduced voltage is passed through an internal power generator 10311 to generate a voltage VDD, which powers other blocks. The bandgap reference 10321 generates a reference voltage which does not change with temperature, when external control devices such as bluetooth, WIFI or other intelligent modules output PWM signals, the PWM signals are sent to the logic controller 10331, the logic controller 10331 generates a second logic signal DIMP and a first logic signal DIMN, and due to the existence of the input capacitance of the third switch 1037, the gate voltage of the third switch 1037 rises slowly, the second logic signal DIMP is a driving signal of the second switch 1035, and the second switch 1035 mainly pulls up the gate voltage of the third switch 1037 as soon as possible after the falling edge of the first logic signal DIMN arrives. So that the output current coincides as much as possible with the switching speed of the PWM signal. The second current source IB2 provides a bias current for the first operational amplifier OP, the first current source 1034 pulls up a reference current for the gate voltage of the third switch 1037, as shown in fig. 4, the current waveform flowing through the third switch 1037 is divided into an a signal without the second current source IB2 and a B signal with the second current source IB2, the time when the B signal with the second current source IB2 is increased to the same current is shortened from t2 to t1, it can be obviously obtained that the voltage increasing speed of the third switch 1037 is increased, thereby increasing the duty ratio of the current value output by the corresponding third switch 1037, greatly increasing the phase margin of the constant current loop, and increasing the dimming depth.
In order to achieve the above object, the present invention further provides a dimming system, which includes a plurality of LED dimming devices as described above, and the plurality of LED dimming devices are arranged in parallel.
It can be understood that, because the above-mentioned LED dimming device is used in the dimming system of the present invention, the embodiments of the dimming system of the present invention include all the technical solutions of all the embodiments of the above-mentioned LED dimming device, and the achieved technical effects are identical, and are not repeated herein. Meanwhile, the plurality of LED dimming devices are arranged in parallel, so that the output of larger power can be realized.
Alternatively, the input terminals of the control circuits 1033 of the plurality of LED dimming devices are connected to one/more external control apparatuses, and the control circuits 1033 of the plurality of LED dimming devices receive a plurality of identical/different PWM signals.
In the first embodiment, the input terminals of the control circuits 1033 of the plurality of LED dimming devices are connected to one external control apparatus, and the control circuits 1033 of the plurality of LED dimming devices receive the same PWM signal. Thus, the two functions of color mixing and light adjusting can be realized, and the LED lamp set 102 can be a white LED or a color LED. At this time, all brightness variations of the LED lamp group 102 remain uniform, and synchronous color mixing and dimming can be achieved.
In the second embodiment, the input terminals of the control circuits 1033 of the plurality of LED dimming devices are connected to one external control apparatus, and the control circuits 1033 of the plurality of LED dimming devices receive a plurality of different PWM signals. At this time, the same external control device outputs a plurality of control signals to control the changes of the LED lamp groups 102 of the plurality of LED dimming devices, at this time, separate control of different LED lamp groups 102 can be realized, when the LED lamp groups 102 are white LEDs, there are more changes in brightness, and when the LED lamp groups 102 are color LEDs, there are more changes in color.
In the third embodiment, the input terminals of the control circuits 1033 of the plurality of LED dimming devices are connected to a plurality of external control apparatuses, and the control circuits 1033 of the plurality of LED dimming devices receive a plurality of different PWM signals. The specific principle is referred to the second embodiment and will not be described here in detail.
In the fourth embodiment, the input terminals of the control circuits 1033 of the plurality of LED dimming devices are connected to a plurality of external control apparatuses, and the control circuits 1033 of the plurality of LED dimming devices receive a plurality of identical PWM signals. The specific principle is referred to the first embodiment and will not be described here in detail.
Optionally, the power supply circuit 101 includes a voltage source, a first diode, a second diode, a third diode, and a fourth diode.
The first diode, the second diode, the third diode and the fourth diode form a rectifier bridge together, the alternating voltage is converted into direct voltage, the direct voltage flows through the LED lamp string, and stable working electricity is provided for the whole circuit.
The foregoing description of the preferred embodiments of the present invention should not be construed as limiting the scope of the invention, but rather should be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following description and drawings or any application directly or indirectly to other relevant art(s).

Claims (9)

1. The LED dimming device comprises a power supply circuit, an LED lamp group and a driving circuit, and is characterized in that the driving circuit comprises a voltage drop circuit, a reference voltage circuit, a control circuit, a first switch, a second switch, a third switch and a first current source; the control circuit comprises a Schmitt trigger, a first inverter, a second inverter, a third inverter, a fourth inverter, a fifth inverter, a sixth inverter, a third current source, a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a first capacitor and a NAND gate, wherein the input end of the Schmitt trigger is a control signal input end of the control circuit, and the output end of the Schmitt trigger is connected with the input end of the first inverter; the output end of the first inverter is connected with the input end of the second inverter, and the output end of the second inverter is connected with the input end of the third inverter; the output end of the third inverter, the input end of the sixth inverter, the first input end of the NAND gate, the grid electrode of the first MOS tube and the grid electrode of the second MOS tube are interconnected; the source of the first MOS tube is the power supply input end of the control circuit, and the drain electrode of the first MOS tube, the drain electrode of the second MOS tube, the first end of the first capacitor and the input end of the fourth inverter are interconnected; the source electrode of the second MOS tube is connected with the drain electrode of the third MOS tube, the source electrode of the third MOS tube, the substrate of the second MOS tube, the source electrode of the fourth MOS tube and the second end of the first capacitor are all grounded, and the grid electrode of the third MOS tube, the grid electrode of the fourth MOS tube, the drain electrode of the fourth MOS tube and the output end of the third current source are connected; the input end of the third current source is connected with the output end of the voltage drop circuit; the output end of the sixth inverter is a first output end of the control circuit; the output end of the fourth inverter is connected with the input end of the fifth inverter, the output end of the fifth inverter is connected with the second input end of the NAND gate, and the output end of the NAND gate is the second output end of the control circuit;
the power supply circuit is used for providing working power supply for the LED lamp group;
the voltage drop circuit is used for providing working voltages for the control circuit, the reference voltage circuit and the first current source;
the reference voltage circuit is used for outputting a preset reference voltage;
the control circuit is used for receiving a PWM signal, outputting a first logic signal to control the on or off of the first switch according to the received PWM signal, and outputting a second logic signal to control the off or on of the second switch at the same time, wherein the first switch and the second switch are controlled in forward and reverse directions, namely when the first switch is on, the second switch is off, and when the first switch is off, the second switch is on;
the third switch is used for being conducted when the preset reference voltage value is received, and when the first switch is conducted, the output current value is changed according to the first logic signal;
the first current source is configured to output a pull-up voltage to the third switch when the second switch is turned on, so as to accelerate a voltage rising speed of a controlled terminal of the third switch.
2. The LED dimmer arrangement as set forth in claim 1, wherein the control circuit comprises a power supply input, a control signal input, a first output and a second output, the output of the power supply circuit being connected to the input of the LED lamp bank, the output of the LED lamp bank, the input of the voltage drop circuit and the first end of the third switch being interconnected, the connection node of the voltage drop circuit and the third switch being the input of the driver circuit, the output of the voltage drop circuit, the input of the reference voltage circuit, the power supply input of the control circuit and the input of the first current source being interconnected; the control signal input end of the control circuit is connected with external control equipment, the first output end of the control circuit is connected with the controlled end of the first switch, and the second output end of the control circuit is connected with the controlled end of the second switch; the output end of the reference voltage circuit, the first end of the first switch, the first end of the second switch and the controlled end of the third switch are interconnected, and the second end of the first switch is the grounding end of the driving circuit; the second end of the second switch is connected with the output end of the first current source; the second end of the third switch is the output end of the driving circuit.
3. The LED dimmer arrangement as set forth in claim 2, wherein the driver circuit is integrated on a driver chip.
4. The LED dimmer device as set forth in claim 2, further comprising a ground resistor, wherein the output of the driver circuit is connected to a first end of the ground resistor, and wherein the ground of the driver circuit and a second end of the ground resistor are grounded.
5. The LED dimmer device according to claim 2, wherein the voltage drop circuit comprises a field effect transistor and an internal power supply generator, wherein the gate of the field effect transistor is grounded, the drain of the field effect transistor is an input terminal of the voltage drop circuit, the source of the field effect transistor is connected to the input terminal of the internal power supply generator, and the output terminal of the internal power supply generator is an output terminal of the voltage drop circuit.
6. The LED dimmer apparatus as set forth in claim 2, wherein the reference voltage circuit comprises a bandgap reference, a first operational amplifier and a second current source, the input of the bandgap reference and the input of the second current source being connected, the connection node of the bandgap reference and the second current source being the input of the reference voltage circuit, the output of the bandgap reference being connected to the positive input of the first operational amplifier; the output end of the second current source is connected with the power end of the first operational amplifier, the reverse input end of the first operational amplifier is connected with the second end of the third switch, and the output end of the first operational amplifier is the output end of the reference voltage circuit.
7. The LED dimmer arrangement according to any one of claims 1-6, wherein the first and third switches are N-MOS transistors and the second switch is a P-MOS transistor.
8. A dimming system comprising a plurality of LED dimming devices according to any one of claims 1 to 7, wherein a plurality of the LED dimming devices are arranged in parallel.
9. A dimming system as claimed in claim 8, wherein the input terminals of the control circuits of a plurality of said LED dimming devices are connected to one or more external control devices, the control circuits of a plurality of said LED dimming devices receiving the same/different PWM signals.
CN201811490642.9A 2018-12-06 2018-12-06 LED dimming device and dimming system Active CN109302777B (en)

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CN111083826B (en) * 2019-12-25 2021-08-03 上海芯飞半导体技术有限公司 LED drive circuit capable of adjusting brightness and color
CN115460734B (en) * 2022-05-17 2023-12-01 深圳锐盟半导体有限公司 LED control circuit, electronic equipment and electronic device

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CN102413600A (en) * 2010-09-25 2012-04-11 台达电子工业股份有限公司 Luminous device and control method thereof
CN104470099A (en) * 2014-11-26 2015-03-25 成都岷创科技有限公司 Light emitting diode driving circuit
CN204259229U (en) * 2014-11-26 2015-04-08 成都岷创科技有限公司 Exchange the current mode LED fast start circuit driven
CN209419956U (en) * 2018-12-06 2019-09-20 深圳市德信创微电子有限公司 LED dimming device and light adjusting system

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Publication number Priority date Publication date Assignee Title
CN102413600A (en) * 2010-09-25 2012-04-11 台达电子工业股份有限公司 Luminous device and control method thereof
CN104470099A (en) * 2014-11-26 2015-03-25 成都岷创科技有限公司 Light emitting diode driving circuit
CN204259229U (en) * 2014-11-26 2015-04-08 成都岷创科技有限公司 Exchange the current mode LED fast start circuit driven
CN209419956U (en) * 2018-12-06 2019-09-20 深圳市德信创微电子有限公司 LED dimming device and light adjusting system

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