CN115996499A - LED drive circuit and LED lighting system - Google Patents

LED drive circuit and LED lighting system Download PDF

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Publication number
CN115996499A
CN115996499A CN202211501601.1A CN202211501601A CN115996499A CN 115996499 A CN115996499 A CN 115996499A CN 202211501601 A CN202211501601 A CN 202211501601A CN 115996499 A CN115996499 A CN 115996499A
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driving
reference signal
current
led
signal
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伍陈灿
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Joulwatt Technology Co Ltd
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Joulwatt Technology Co Ltd
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Abstract

The application discloses a multichannel LED drive circuit and an LED lighting system. The LED driving circuit is used for respectively providing respective driving currents for the LED lamps of a plurality of channels, and comprises: a first driving unit for providing a first driving current and a second driving current to the LED of the first channel and the LED of the second channel, respectively, the first driving unit adjusting the first driving current and the second driving current according to a reference signal; and the second driving unit is used for providing a third driving current for the LED of the third channel, and is connected with a loop where the LED of the first channel is positioned to obtain a first sampling signal, wherein the first sampling signal characterizes the working state of the LED of the first channel, and the second driving unit adjusts the third driving current according to the first sampling signal. Thereby the LED working state of the third channel follows the working state of the first channel LED, and when the first channel LED is lighted, power supplement is provided.

Description

LED drive circuit and LED lighting system
Technical Field
The present invention relates to the field of power electronics, and in particular, to an LED driving circuit and an LED lighting system for supplying respective driving currents to LED lamps of a plurality of channels, respectively.
Background
The LED illumination is used as a novel illumination tool, has the advantages of high light efficiency, long service life, environmental protection and the like, and is also increasingly widely applied to various illumination fields. Dimming and toning are carried out on the LED light source, so that comfortable illumination can be provided for a user, and meanwhile, energy conservation and environmental protection are facilitated. Dimming, that is, adjusting the brightness of a light source, is generally achieved by PWM dimming, silicon controlled dimming, or the like; the color mixing, that is, the color mixing temperature is regarded as adjusting the color of the light source in a popular manner, and the color temperature of the LED is determined by the light source, and the color rendering index is different from one light source to another. The color temperature adjusting function of the LEDs in the prior art is usually to adjust colors in a segmented mode, for example, the on-off of two light strings with different color temperatures are switched in a switching mode, so that the purpose of color adjustment is achieved. Taking two paths of outputs of a cold color temperature light string and a warm color temperature light string as an example, when the cold color temperature light string is fully lighted, bright cold light is provided; when the warm color temperature lamp string is fully on, soft warm light is provided; when the cold color temperature lamp string and the warm color temperature lamp string are half-on, comfortable mixed light is provided, so that a user can obtain comfortable illumination in different environments.
In practical use, the fully lit mode of the cold color temperature light string is usually to provide enough illumination, and to ensure that the LEDs have enough luminous flux, multiple LED lamps need to be connected in series/parallel. However, in the LED lighting system, since the cold color temperature string and the warm color temperature string need to be adjusted synchronously, currents through the cold color temperature string and the warm color temperature string are correlated, so that it is difficult to individually extend the main lamp power.
Disclosure of Invention
In view of the foregoing, it is an object of the present invention to provide an LED driving circuit and an LED lighting system for supplying respective driving currents to LED lamps of a plurality of channels, respectively, so as to satisfy the power supplement requirement.
According to an aspect of the present invention, there is provided a multi-channel LED driving circuit for supplying respective driving currents to LED lamps of a plurality of channels, respectively, the driving circuit comprising: a first driving unit for providing a first driving current and a second driving current to the LED of the first channel and the LED of the second channel, respectively, the first driving unit adjusting the first driving current and the second driving current according to a reference signal; and the second driving unit is used for providing a third driving current for the LED of the third channel, and is connected with a loop where the LED of the first channel is positioned to obtain a first sampling signal, wherein the first sampling signal characterizes the working state of the LED of the first channel, and the second driving unit adjusts the third driving current according to the first sampling signal.
Optionally, when the first sampling signal characterizes that the LED of the first channel is turned on, the second driving unit drives the LED of the third channel to be turned on, and when the first sampling signal characterizes that the LED of the first channel is turned off, the second driving unit drives the LED of the third channel to be turned off.
Optionally, the second driving unit further adjusts the magnitude of the third driving current according to the first sampling signal.
Optionally, the reference signal includes a first reference signal and a second reference signal, and the first driving unit adjusts the first driving current according to the first reference signal and adjusts the second driving current according to the second reference signal.
Optionally, the maximum value of the first reference signal is greater than the maximum value of the second reference signal.
Optionally, the first driving unit includes: the first current control module is used for adjusting the first reference signal and the second reference signal according to the dimming signal; the first branch is connected with the first current control module and the LED of the first channel, receives the first reference signal and adjusts the first driving current according to the first reference signal; and a second branch connected with the first current control module and the LED of the second channel, receiving the second reference signal, and adjusting the second driving current according to the second reference signal.
Optionally, sampling a negative terminal voltage of the LED of the first channel obtains the first sampling signal.
Optionally, the first branch includes: a first operational amplifier outputting a first driving signal according to the first reference signal; and a first transistor adjusting the first driving current according to the first driving signal; the second branch includes: a second operational amplifier outputting a second driving signal according to the second reference signal; and a second transistor adjusting the second driving current according to the second driving signal.
Optionally, the first current control module adjusts the first reference signal and the second reference signal according to a dimming signal, including: adjusting the first reference signal to be maximum, the second reference signal to be zero, and enabling the first driving current to be the first maximum working current and the second driving current to be zero; adjusting the second reference signal to be maximum, wherein the first reference signal is zero, so that the second driving current is the second maximum working current; the first drive current is zero; and adjusting the first reference signal to be half of the maximum value, and adjusting the second reference signal to be half of the maximum value, so that the first driving current is half of the first maximum working current, and the second driving current is half of the second maximum working current.
Optionally, the second driving unit includes: the power module comprises a first input end and a first output end, wherein the first input end receives the first sampling signal, and the first output end outputs the third driving current; the sampling filter module is connected with the first driving unit and the power module and is used for sampling and processing the first sampling signal; the power module receives the first sampling signal and outputs a third reference signal according to the first sampling signal, so that the third driving current is regulated.
Optionally, the value of the third reference signal is a preset fixed value.
Optionally, the second driving unit includes a first resistor connected between the sampling filter module and the power module, wherein the third reference signal may be adjusted by adjusting a resistance value of the first resistor.
Optionally, the power module includes: the second current control module is used for generating the third reference signal according to the first sampling signal; a third operational amplifier outputting a third driving signal according to the third reference signal; and a third transistor adjusting the third driving current according to the third driving signal.
Optionally, the second current control module includes a sink unit for generating the third reference signal having a sink waveform.
Optionally, the LEDs of the first channel are different in color temperature from the LEDs of the second channel.
According to a second aspect of the present invention, there is provided an LED lighting system comprising: an LED lamp serving as a light source; the light modulator is used for adjusting the current of the LED lamp according to the light modulating action, and the rectifier bridge is connected with the light modulator and used for rectifying the alternating current input voltage to generate direct current input voltage; and a drive circuit according to any one of claims 1 to 15, wherein the LED lamp and the drive circuit are connected in series in sequence between the first and second output terminals of the rectifier bridge.
Optionally, the dimmer comprises a switching dimmer and/or a thyristor dimmer.
According to the LED driving circuit, the third reference signal is regulated through the first sampling signal representing the working state of the LED of the first channel, so that the third driving current is regulated, and the working state of the power module follows the working state of the LED of the first channel, namely, when the LED of the first channel does not work, the power module is closed; when the LEDs of the first channel work, the power module works and outputs the third driving current, so that the output power of the whole lighting system is improved, and the occasion demands of high power and high luminous flux are met.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 shows a schematic circuit diagram of a prior art LED lighting system;
fig. 2 shows a schematic circuit diagram of an LED lighting system according to a first embodiment of the invention;
FIG. 3 shows a schematic diagram of the composition of a power module in the LED lighting system of FIG. 2;
fig. 4 shows an equivalent circuit diagram of a second driving unit in the LED lighting system shown in fig. 2;
fig. 5 shows a schematic circuit diagram of an LED lighting system according to a second embodiment of the invention;
fig. 6 shows an operational waveform diagram of the LED lighting system shown in fig. 5.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown.
Numerous specific details of the invention, such as device structures, materials, dimensions, processing techniques and technologies, are set forth in the following description in order to provide a thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
It should be noted that in this document relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Fig. 1 shows a schematic circuit diagram of an LED lighting system according to the prior art.
The LED lighting system 100 includes a switch S1, a rectifier bridge 102, a first driving unit 110, an LED lamp 103, and an LED lamp 104.
The ac power source 101 is connected to two ac input terminals of the rectifier bridge 102 via a switch S1. The ac power supply 101 is, for example, a commercial ac power supply or a UPS power supply. Ac power supply 101 provides ac power supply voltage V AC For example, an alternating supply voltage V AC May be a sinusoidal waveform ac voltage at a nominal frequency (also referred to as "power frequency") of 50 Hz. The rectifier bridge 102 rectifies the ac input voltage to obtain a dc input voltage V BUS
The LED lighting system 100 provides two outputs, LED 103 and LED 104, with the LED 103 and LED 104 having different color temperatures in some embodiments, for example, LED 103 being a cool light lamp and LED 104 being a warm light lamp. According to the action of the user on the switch S1, the first current control module 111 outputs different reference signals V C1 V (V) C2 Thereby adjusting the current states of the LED lamp 103 and the LED lamp 104, and realizing the color temperature adjustment of the LED lighting system. Further, in some embodiments, reference signal V C1 Is greater than the reference signal V C2 Is a maximum value of (a).
Referring to fig. 1, the first driving unit 110 includes a first current control module 111, operational amplifiers U1, U2, transistors M1, M2, and resistors R1, R2. Wherein the LED lamp 103, the transistor M1, and the resistor R1 are sequentially connected in series as a branch between the first dc output end and the second dc output end of the rectifier bridge 102, the transistor M1 is used for controlling the current (i.e. the current I) flowing through the LED lamp 103 LED1 ) Resistor R1 is used to obtain the sampling current V of LED lamp 103 CS1 The method comprises the steps of carrying out a first treatment on the surface of the The LED lamp 104, the transistor M2, and the resistor R2 are sequentially connected in series as another branch between the first dc output end and the second dc output end of the rectifier bridge 102, and the transistor M2 is used for controlling the current (i.e. the current I) flowing through the LED lamp 104 LED2 ) Resistor R2 is used to obtain the sampling current V of LED lamp 104 CS2 . A first input terminal of the first current control module 111 is connected to a first dc output terminal of the rectifier bridge 102 to obtain a dc input voltage V BUS . The first output terminal and the second output terminal of the first current control module 111 are respectively connected with the same-direction input terminals of the operational amplifiers U1 and U2The input terminal is connected to output a reference signal V obtained by the operation of the switch S1 C1 And V C2 . Wherein the reference signal V C1 And V C2 Is a preset value that characterizes the desired operating current.
An inverting input terminal of the operational amplifier U1 is connected to an intermediate node of the transistor M1 and the resistor R1 for receiving the current sampling signal V CS1 The method comprises the steps of carrying out a first treatment on the surface of the The output end is connected with the control end of the transistor M1; the operational amplifier U1 is based on the reference signal V C1 And current sampling signal V CS1 Output control signal V G1 The transistor M1 is adjusted so as to adjust the current flowing through the LED lamp 103 to obtain a desired operating current. An inverting input terminal of the operational amplifier U2 is connected to an intermediate node of the transistor M2 and the resistor R2 for receiving the current sampling signal V CS2 The method comprises the steps of carrying out a first treatment on the surface of the The output end is connected with the control end of the transistor M2; operational amplifier U2 based on reference signal V C2 And current sampling signal V CS2 Output control signal V G2 Transistor M2 is adjusted to adjust the current through LED lamp 104 to achieve a desired operating current.
Further, in some embodiments, V C1 And V C2 The first current control module 111 can set a multi-gear preset value and select and output V with different gears according to the action of the switch S1 C1 And V C2 Thereby realizing the segmented dimming and toning. Illustratively V C1 And V C2 Three preset values can be set, which correspond to a main lamp mode, a night lamp mode and a light mixing mode respectively. The first current control module 111 outputs different reference signals V according to the operation of the switch S1 C1 And V C2 Thereby adjusting the current flowing through the LED lamp 103 and the LED lamp 104, so that the LED lamp 104 is extinguished when the LED lamp 103 is lighted and reaches the maximum working current in the main lamp mode; in night lamp mode, the LED lamp 103 is turned off, and the LED lamp 104 is turned on and reaches the maximum operating current; in the mixed light mode, the LED lamp 103 and the LED lamp 104 are both lighted, and the current flowing through the LED lamp 103 and the LED lamp 104 reaches half of the maximum working current of the mixed light mode, so that three-stage dimming and color mixing of the LED lighting system are realized.
Fig. 2 shows a schematic circuit diagram of an LED lighting system according to a first embodiment of the invention. The LED lighting system 200 includes a dimmer 210, a rectifier bridge 202, a first driving unit 220, a second driving unit 230, an LED lamp 203, an LED lamp 204, and an LED lamp 205.
An ac power supply 201 is connected to two ac inputs of the rectifier bridge 202 via a dimmer 210. The ac power supply 201 is, for example, a commercial ac power supply or a UPS power supply. Ac power supply 201 provides ac power supply voltage V AC For example, an alternating supply voltage V AC Is a sinusoidal waveform ac voltage of 50Hz rated frequency (also referred to as "power frequency"). The rectifier bridge 202 rectifies the ac input voltage to obtain a dc input voltage V BUS
Dimmer 210 includes a switch S1 and LED lighting system 200 provides three outputs, LED lamp 203, LED lamp 204, and LED lamp 205. In some embodiments, the color temperatures of the LED lamp 203 and the LED lamp 204 are different, and the LED lamp 203 is a cold light lamp and the LED lamp 204 is a warm light lamp.
The first driving unit 220 and the second driving unit 230 are sequentially connected to the rectifier bridge 202, and the first driving unit 220 adjusts the current flowing through the LED lamp 203 and the LED lamp 204 according to the switching action of the user to adjust the color temperature of the LED lamp, so as to provide comfortable illumination. The second driving unit 230 adjusts the current flowing through the LED lamp 205 according to the operating state of the LED lamp 203 to provide power supplement, thereby improving the output power of the overall lighting system and meeting the occasion demands of high power and high luminous flux.
In some embodiments, the user may also change the total load current of the LED lighting system 200 by operating the switch S1, for example, when the LED lamp 203 reaches a maximum operating current, the LED lamp 205 is turned on, the total load current of the lighting system is maximum, when the LED lamp 203 is turned off, the LED lamp 205 is turned off, and the total load current of the lighting system is minimum, thereby achieving brightness adjustment of the LED lighting system 200.
The circuit structure and the operation principle of the first driving unit 220 in the LED lighting system according to the present embodiment are substantially the same as those of the first driving unit 110 used in the related art shown in fig. 1, and a detailed description thereof is omitted herein.
Referring to fig. 2, the second driving unit 230 includes a power module 231, a resistor R3, and a driving circuitSample filtering module 232. Further, the sampling filter module 232 includes resistors R4, R5 and a capacitor C O . Wherein, the resistor R4 and the resistor R5 are connected in series and then connected between the negative terminal of the LED lamp 203 and the second DC output terminal of the rectifier bridge 202, the capacitor C O As a filter circuit, a resistor R5 is connected in parallel. Resistor R3 is connected between power module 231 and the intermediate node of resistors R4 and R5.
Since the forward voltage of the LED lamp group is different in the on/off state (i.e. on state/off state), the negative terminal voltage V of the LED lamp 203 and the LED lamp 204 LED1 And V LED2 May exhibit significant differences in different operating conditions, e.g., current I when LED lamp 203 is extinguished LED1 Is 0, V LED1 Higher; when the LED lamp 203 is lighted, the current I LED1 Is not 0, V LED1 Lower. Resistor R4 and resistor R5 provide a negative voltage V to LED lamp 203 LED1 Sampling is carried out and is carried out through a capacitor C O Filtering to obtain a sampling signal V representing the working state of the LED lamp 203 FB
Referring to fig. 3, the power supplementing module 231 includes a second current control module 2311, an operational amplifier U3, a transistor M3, and a resistor R6. Wherein the LED lamp 205, the transistor M3, and the resistor R6 are sequentially connected in series between the first dc output end and the second dc output end of the rectifier bridge 202, the transistor M3 is used for controlling the current (i.e. the current I) flowing through the LED lamp 205 LED3 ) Resistor R6 is used to obtain the sampling current V of LED lamp 205 CS3 . A first input terminal of the second current control module 2311 is connected to a resistor R3 for sampling the signal V FB Is input to second current control module 2311 through resistor R3. A second input of second current module 2311 is coupled to a negative electrode of LED lamp 205. The first output terminal of the second current control module 2311 is connected to the common input terminal of the operational amplifier U3 according to the sampling signal V FB Output reference signal V C3 Is 0 or a preset value, e.g. when sampling signal V FB When the threshold value is smaller, the reference signal V is output C3 Is a preset value; when sampling signal V FB When the threshold is reached, the reference signal V is output C3 Is 0. The inverting input of the operational amplifier U3 is connected to the intermediate node of the transistor M3 and the resistor R6Receiving a sampling current signal V CS3 The operational amplifier U3 is based on the reference signal V C3 And sampling the current signal V CS3 Output drive signal V G3 Transistor M3 is adjusted to regulate the current I flowing through LED lamp 205 LED3 . Further, the reference signal V can be adjusted by adjusting the resistance value of the resistor R3 C3 The magnitude of the preset value is preset, so that the peak current of the power module 231 is adjusted.
Further, in the present embodiment, the second current control module 2311 further includes a sink unit (not shown) to generate the reference signal V with a sink waveform C3 Thereby obtaining the load current I with a concave waveform LED3 It is advantageous to improve the working efficiency of the second driving unit 231.
Referring to FIG. 4, the sampling filter module 232 may be equivalently connected in series V between the resistor R3 and the second DC input of the rectifier bridge 202 FB A voltage signal. The positive voltage V of the LED lamps 203 and 204 is caused by the different performances of the on/off states (i.e. the on/off states) of the LED lamp groups LED1 And V LED2 May also exhibit a significant difference in voltage, e.g., V when the LED lamp 203 is lit LED1 Lower; when the LED lamp 203 is turned off, V LED1 Higher. In some embodiments, when the LED lamp 203 is turned off, a current I flows through the LED lamp 203 LED1 0, sample signal V FB Rising to threshold value, the second current control module outputs reference signal V C3 0, thereby making I LED3 Is 0, i.e. the second drive unit 230 is turned off. When the LED lamp 203 is turned on, the current flowing through the LED lamp 203 gradually increases, and the voltage V of the negative electrode of the LED lamp 203 LED1 Gradually decrease, reference signal V FB Then decrease, the second current control module outputs the reference signal V C3 Is a preset value such that a current I flows through the third LED lamp set 205 LED3 The second driving unit 230 provides the supplementary power gradually, so that the output power of the whole lighting system is improved, and the occasion demands of high power and high luminous flux are met.
Fig. 5 shows a schematic circuit diagram of an LED lighting system of a second embodiment of the invention. LED lighting system 300 includes a dimmer 310, a rectifier bridge 302, a first drive unit 320, a second drive unit 330, an LED lamp 303, an LED lamp 304, an LED lamp 305, and a bleeder circuit 306.
Unlike the LED lighting system 200 of the first embodiment of the present invention shown in fig. 3, the dimmer 310 of the LED lighting system 300 includes a switch S1 and a thyristor dimmer 311, and correspondingly, the LED lighting system 300 further includes a bleeder circuit 306 connected between the first dc output terminal and the second dc output terminal of the rectifier bridge 302. The conduction angle of the thyristor can be changed by the dimming action of the thyristor dimmer 311 to supply the alternating current voltage V AC Chopping to obtain phase-cut AC input voltage V CUT . With respect to the ac supply voltage V AC In other words, V CUT The effective voltage of the (c) is related to the conduction angle of the silicon controlled rectifier, so that the dimming action of the silicon controlled rectifier dimmer 311 can change the brightness of the LED lighting system, so that the regulated light is more stable. Accordingly, the LED lighting system further includes a bleeder circuit 306, and the bleeder circuit 306 can maintain the load current of the thyristor at a level greater than the maintaining current of the thyristor, so as to solve the problem that the load current of the thyristor is small, which results in early turn-off of the thyristor, resulting in LED flickering and limitation of the dimming range.
Fig. 6 illustrates an operational waveform diagram of the LED lighting system 300 shown in fig. 5. Taking three-section color mixing as an example, the LED lighting system comprises a main lamp mode, a night lamp mode and a light mixing mode. As shown in the figure, V LED1 And V LED2 Respectively representing the voltage at the negative terminals of the LED lamp 303 and the LED lamp 304, I LED1 Indicating the current through the LED lamp 303, I LED2 Indicating the current through the LED lamp 304, I LED3 Indicating the current through the LED lamp 305, the number of switches is used to adjust the color temperature of the LED lighting system in segments. In the main lamp mode, the LED lamp 303 is turned on and I LED1 Maximum operating current I for LED lamp 303 1 The LED lamp 304 is turned off, and the negative terminal voltage of the LED lamp 303 is lower at this time, so that the sampling signal V FB The second current control module outputs a reference signal V C3 To a preset value to enable the power module 231 to output a power supplementing current I with a concave waveform LED3 The method comprises the steps of carrying out a first treatment on the surface of the In the light mixing mode, the LED lamp303 and the LED lamp 304 are both in a lighting state, and I LED1 1/2I 1 ,I LED2 1/2I 2 (I 1 For the maximum operating current of the LED lamp 303, I 2 Maximum working current of the LED lamp 304), the negative terminal voltage of the LED lamp 303 is low, and the second current control module still outputs the reference signal V C3 Thereby causing the power module 231 to output the power complementary current I having a concave waveform LED3 The method comprises the steps of carrying out a first treatment on the surface of the In night light mode, LED lamp 304 is illuminated and I LED2 Maximum operating current I for LED lamp 304 2 LED lamp 303 is extinguished, V FB The second current control module outputs a reference signal V when the threshold value is reached C3 0, thereby making I LED3 At 0, the second driving unit is turned off.
Embodiments in accordance with the present invention, as described above, are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and the full scope and equivalents thereof.

Claims (17)

1. A multi-channel LED driving circuit for providing respective driving currents to LED lamps of a plurality of channels, respectively, the driving circuit comprising:
a first driving unit for providing a first driving current and a second driving current to the LED of the first channel and the LED of the second channel, respectively, the first driving unit adjusting the first driving current and the second driving current according to a reference signal; and
a second driving unit for providing a third driving current to the LED of the third channel, the second driving unit being connected to the loop where the LED of the first channel is located to obtain a first sampling signal,
the first sampling signal characterizes the working state of the first channel LED, and the second driving unit adjusts the third driving current according to the first sampling signal.
2. The drive circuit of claim 1, wherein the second drive unit drives the LEDs of the third channel to light when the first sampling signal characterizes the LEDs of the first channel to light,
when the first sampling signal represents that the LEDs of the first channel are turned off, the second driving unit drives the LEDs of the third channel to be turned off.
3. The drive circuit of claim 1, wherein the second drive unit further adjusts a magnitude of the third drive current according to the first sampling signal.
4. The driving circuit according to claim 1, wherein,
the reference signal includes a first reference signal and a second reference signal, and the first driving unit adjusts the first driving current according to the first reference signal and adjusts the second driving current according to the second reference signal.
5. The drive circuit of claim 4, wherein a maximum value of the first reference signal is greater than a maximum value of the second reference signal.
6. The driving circuit of claim 4, wherein the first driving unit comprises:
the first current control module is used for adjusting the first reference signal and the second reference signal according to the dimming signal;
the first branch is connected with the first current control module and the LED of the first channel, receives the first reference signal and adjusts the first driving current according to the first reference signal; and
and the second branch is connected with the first current control module and the LED of the second channel, receives the second reference signal and adjusts the second driving current according to the second reference signal.
7. The drive circuit of claim 6, wherein sampling a negative terminal voltage of the LED of the first channel obtains the first sampled signal.
8. The drive circuit of claim 6, wherein the first branch comprises:
a first operational amplifier outputting a first driving signal according to the first reference signal; and
a first transistor for adjusting the first driving current according to the first driving signal;
the second branch includes:
a second operational amplifier outputting a second driving signal according to the second reference signal; and
and a second transistor for adjusting the second driving current according to the second driving signal.
9. The drive circuit of claim 6, wherein the first current control module adjusts the first and second reference signals according to a dimming signal comprises:
adjusting the first reference signal to be maximum, the second reference signal to be zero, and enabling the first driving current to be the first maximum working current and the second driving current to be zero;
adjusting the second reference signal to be maximum, wherein the first reference signal is zero, so that the second driving current is the second maximum working current; the first drive current is zero;
and adjusting the first reference signal to be half of the maximum value, and adjusting the second reference signal to be half of the maximum value, so that the first driving current is half of the first maximum working current, and the second driving current is half of the second maximum working current.
10. The drive circuit of claim 1, wherein the second drive unit comprises:
the power module comprises a first input end and a first output end, wherein the first input end receives the first sampling signal, and the first output end outputs the third driving current;
the sampling filter module is connected with the first driving unit and the power module and is used for sampling and processing the first sampling signal;
the power module receives the first sampling signal and outputs a third reference signal according to the first sampling signal, so that the third driving current is regulated.
11. The driving circuit of claim 10, wherein the value of the third reference signal is a preset fixed value.
12. The drive circuit of claim 10, wherein the second drive unit comprises a first resistor connected between the sampling filter module and the power module, wherein the third reference signal is adjustable by adjusting the first resistor resistance.
13. The drive circuit of claim 10, wherein the power module comprises:
the second current control module is used for generating the third reference signal according to the first sampling signal;
a third operational amplifier outputting a third driving signal according to the third reference signal; and
and a third transistor adjusting the third driving current according to the third driving signal.
14. The drive circuit of claim 10, wherein the second current control module includes a sink unit for generating the third reference signal having a sink waveform.
15. The drive circuit of claim 1, wherein the LEDs of the first channel are different from the LEDs of the second channel in color temperature.
16. An LED lighting system, comprising:
an LED lamp serving as a light source;
a dimmer for adjusting the current of the LED lamp according to the dimming action,
the rectifier bridge is connected with the dimmer and used for rectifying the alternating current input voltage to generate direct current input voltage; and
the drive circuit according to any one of claims 1 to 15, wherein the LED lamp and the drive circuit are connected in series in sequence between a first output and a second output of the rectifier bridge.
17. The lighting system of claim 16, wherein the dimmer comprises a switching dimmer and/or a thyristor dimmer.
CN202211501601.1A 2022-11-28 2022-11-28 LED drive circuit and LED lighting system Pending CN115996499A (en)

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CN202211501601.1A Pending CN115996499A (en) 2022-11-28 2022-11-28 LED drive circuit and LED lighting system

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