LED driving circuit and LED lighting system

Abstract

The application discloses a multi-channel LED driving circuit and an LED lighting system. The LED driving circuit is used for providing respective driving currents to a plurality of channels of LED lamps respectively, and the LED driving circuit comprises: a first driving unit, used for providing a first driving current and a second driving current to a first channel of LED and a second channel of LED respectively, the first driving unit adjusts the first driving current and the second driving current according to a reference signal; and a second driving unit, used for providing a third driving current to a third channel of LED, the second driving unit is connected with a loop in which the first channel of LED is located to obtain a first sampling signal, wherein the first sampling signal represents a working state of the first channel of LED, and the second driving unit adjusts the third driving current according to the first sampling signal. Thus, the working state of the third channel of LED follows the working state of the first channel of LED, and power supplement is provided when the first channel of LED is lighted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, and in particular to an LED driving circuit and an LED lighting system for providing respective driving currents to a plurality of channels of LED lamps. BACKGROUND

[0002] As a new type of lighting tool, LED lighting has the advantages of high luminous efficiency, long service life, environmental protection, etc., and is therefore increasingly widely used in various lighting fields. Adjusting the light and color of an LED light source can provide comfortable lighting for users and is also conducive to energy saving and environmental protection. Adjusting the light refers to adjusting the brightness of the light source, which is usually achieved by PWM dimming, thyristor dimming, etc. Adjusting the color refers to adjusting the color temperature, which is commonly considered as adjusting the color of the light source. The color temperature of an LED is determined by the light source, and the color rendering index is also different for different light sources. The existing LED color temperature adjusting function is usually segmented, for example, the on-off of a lamp string with two different color temperatures is switched by a switch to achieve the purpose of color adjustment. Taking two-way output of a cold color temperature lamp string and a warm color temperature lamp string as an example, the cold color temperature lamp string provides bright cold light when it is fully on, the warm color temperature lamp string provides soft warm light when it is fully on, and the cold color temperature lamp string and the warm color temperature lamp string provide comfortable mixed light when they are both half on, so that users can obtain comfortable lighting in different environments.

[0003] In actual use, the mode of the cold color temperature lamp string being fully on is usually to provide sufficient lighting. In order to ensure that the LED has sufficient luminous flux, multiple LED lamps need to be connected in series / parallel. However, in an LED lighting system, the cold color temperature lamp string and the warm color temperature lamp string need to be adjusted synchronously, and the currents of the cold color temperature lamp string and the warm color temperature lamp string are related to each other, making it difficult to expand the power of the main lamp alone. SUMMARY

[0004] In view of the above problems, the purpose of the present application is to provide an LED driving circuit and an LED lighting system for providing respective driving currents to a plurality of channels of LED lamps to meet the demand for power supplement.

[0005] According to an aspect of the present application, there is provided a multi-channel LED driving circuit for providing respective driving currents to a plurality of channels of LED lamps, the driving circuit comprising: a first driving unit for providing a first driving current to a first channel of LED and a second driving current to a second channel of LED, 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 a third channel of LED, the second driving unit being connected to a loop in which the first channel of LED is located to obtain a first sampling signal, wherein the first sampling signal represents an operating state of the first channel of LED, and the second driving unit adjusts the third driving current according to the first sampling signal.

[0006] Optionally, when the first sampling signal represents that the first channel of LED is on, the second driving unit drives the third channel of LED to be on, and when the first sampling signal represents that the first channel of LED is off, the second driving unit drives the third channel of LED to be off.

[0007] Optionally, the second driving unit further adjusts a magnitude of the third driving current according to the first sampling signal.

[0008] Optionally, the reference signal comprises a first reference signal and a second reference signal, 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.

[0009] Optionally, a maximum value of the first reference signal is greater than a maximum value of the second reference signal.

[0010] Optionally, the first driving unit comprises: a first current control module for adjusting the first reference signal and the second reference signal according to a dimming signal; a first branch connected to the first current control module and the first channel of LED, receiving the first reference signal and adjusting the first driving current according to the first reference signal; and a second branch connected to the first current control module and the second channel of LED, receiving the second reference signal and adjusting the second driving current according to the second reference signal.

[0011] Optionally, the first sampling signal is obtained by sampling a negative terminal voltage of the first channel of LED.

[0012] Optionally, the first branch comprises: a first operational amplifier configured to output a first driving signal according to the first reference signal; and a first transistor configured to adjust the first driving current according to the first driving signal; and the second branch comprises: a second operational amplifier configured to output a second driving signal according to the second reference signal; and a second transistor configured to adjust the second driving current according to the second driving signal.

[0013] Optionally, the first current control module is configured to adjust the first reference signal to a maximum value and the second reference signal to zero, so as to make the first driving current a first maximum working current and the second driving current zero; adjust the second reference signal to a maximum value and the first reference signal to zero, so as to make the second driving current a second maximum working current and the first driving current zero; and adjust the first reference signal to half of the maximum value and the second reference signal to half of the maximum value, so as to make the first driving current half of the first maximum working current and the second driving current half of the second maximum working current.

[0014] Optionally, the second driving unit comprises: a power module comprising a first input end and a first output end, the first input end being configured to receive the first sampling signal, and the first output end being configured to output the third driving current; and a sampling filter module connected to the first driving unit and the power module, and configured to sample and process the first sampling signal; wherein the power module receives the first sampling signal and outputs a third reference signal according to the first sampling signal, so as to adjust the third driving current.

[0015] Optionally, the third reference signal has a preset fixed value.

[0016] Optionally, the second driving unit comprises a first resistor connected between the sampling filter module and the power module, wherein the third reference signal can be adjusted by adjusting the resistance value of the first resistor.

[0017] Optionally, the power module comprises: a second current control module configured to generate the third reference signal according to the first sampling signal; a third operational amplifier configured to output a third driving signal according to the third reference signal; and a third transistor configured to adjust the third driving current according to the third driving signal.

[0018] Optionally, the second current control module comprises a concave unit configured to generate the third reference signal having a concave waveform.

[0019] Optionally, the LEDs in the first channel have a different color temperature from the LEDs in the second channel.

[0020] According to a second aspect of the present application, there is provided an LED lighting system, comprising: an LED lamp as a light source; a dimmer for adjusting the LED lamp current according to a dimming action; a rectifier bridge connected to the dimmer for rectifying an AC input voltage to generate a DC input voltage; and the driving circuit according to any one of claims 1 to 15, wherein the LED lamp and the driving circuit are connected in series between a first output terminal and a second output terminal of the rectifier bridge.

[0021] Optionally, the dimmer comprises a switch dimmer and / or a thyristor dimmer.

[0022] According to the LED driving circuit of the present application, the third reference signal is adjusted by the first sampling signal representing the working state of the LED of the first channel, so as to adjust the third driving current, so that the working state of the power module follows the working state of the LED of the first channel, i.e. when the LED of the first channel is not working, the power module is closed; when the LED of the first channel is working, the power module is working, outputting the third driving current, so as to improve the output power of the overall lighting system, meeting the requirements of high power and high luminous flux. BRIEF DESCRIPTION OF DRAWINGS

[0023] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application taken with reference to the accompanying drawings, in which:

[0024] Figure 1 a schematic circuit diagram of an LED lighting system in the prior art is shown;

[0025] Figure 2 a schematic circuit diagram of an LED lighting system according to a first embodiment of the present application is shown;

[0026] Figure 3 a schematic circuit diagram of a power module in the LED lighting system is shown; Figure 2

[0027] a schematic circuit diagram of a second driving unit in the LED lighting system is shown; Figure 4 Figure 2 a schematic circuit diagram of an LED lighting system according to a second embodiment of the present application is shown;

[0028] Figure 5 a working waveform diagram of the LED lighting system is shown.

[0029] Figure 6 Figure 5 a working waveform diagram of the LED lighting system is shown. DETAILED DESCRIPTION

[0030] ​​The invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.

[0031] Many specific details of the invention, such as the structure, materials, dimensions, processing methods, and techniques of the devices, are described below to provide a clearer understanding of the invention. However, as those skilled in the art will understand, the invention may be implemented without following these specific details.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] Figure 1 A schematic circuit diagram of an LED lighting system according to the prior art is shown.

[0034] The LED lighting system 100 includes a switch S1, a rectifier bridge 102, a first drive unit 110, an LED lamp 103, and an LED lamp 104.

[0035] AC power supply 101 is connected to the two AC input terminals of rectifier bridge 102 via switch S1. AC power supply 101 may be, for example, AC mains power or a UPS power supply. AC power supply 101 provides AC supply voltage V. AC For example, AC power supply voltage V AC It can handle sinusoidal AC voltages at a rated frequency (also known as "power frequency") of 50Hz. The rectifier bridge 102 rectifies the AC input voltage to obtain a DC input voltage V. BUS .

[0036] The LED lighting system 100 provides two outputs, namely LED lamp 103 and LED lamp 104. In some embodiments, LED lamp 103 and LED lamp 104 have different color temperatures; for example, LED lamp 103 is a cool light lamp, and LED lamp 104 is a warm light lamp. Based on the user's action on switch S1, the first current control module 111 outputs different reference signals V. C1 and VC2 This adjusts the current state of LED lamps 103 and 104, thereby achieving color temperature adjustment of the LED lighting system. Furthermore, in some embodiments, the reference signal V... C1 The maximum value is greater than the reference signal V. C2 The maximum value.

[0037] See Figure 1 The first driving unit 110 includes a first current control module 111, operational amplifiers U1 and U2, transistors M1 and M2, and resistors R1 and R2. The LED 103, transistor M1, and resistor R1 are connected in series as a branch between the first and second DC output terminals of the rectifier bridge 102. Transistor M1 is used to control the current flowing through the LED 103 (i.e., current I). LED1 Resistor R1 is used to obtain the sampling current V of LED 103. CS1 LED 104, transistor M2, and resistor R2 form another branch connected in series between the first and second DC output terminals of rectifier bridge 102. Transistor M2 is used to control the current flowing through LED 104 (i.e., current I). LED2 Resistor R2 is used to obtain the sampling current V of LED 104. CS2 The first input terminal of the first current control module 111 is connected to the first DC output terminal of the rectifier bridge 102 to obtain the DC input voltage V. BUS The first and second output terminals of the first current control module 111 are connected to the non-inverting input terminals of operational amplifiers U1 and U2, respectively, and output a reference signal V obtained by the action of switch S1. C1 and V C2 Among them, the reference signal V C1 and V C2 It is a preset value that characterizes the desired operating current.

[0038] The inverting input of operational amplifier U1 is connected to the midpoint between transistor M1 and resistor R1 to receive the current sampling signal V. CS1 The output terminal is connected to the control terminal of transistor M1; operational amplifier U1 operates according to the reference signal V. C1 and current sampling signal V CS1 Output control signal V G1 The current flowing through LED 103 is adjusted by regulating transistor M1 to achieve the desired operating current. The inverting input of operational amplifier U2 is connected to the midpoint between transistor M2 and resistor R2 to receive the current sampling signal V. CS2 The output terminal is connected to the control terminal of transistor M2; operational amplifier U2 operates according to the reference signal V. C2 and current sampling signal V CS2 Output control signal VG2 The transistor M2 is adjusted to adjust the current flowing through the LED lamp 104 to obtain a desired operating current.

[0039] Further, in some embodiments, V C1 and V C2 may be set to multiple preset values, and the first current control module 111 selects V C1 and V C2 according to the action of the switch S1 to output different levels of V C1 and V C2 , so as to realize segmented dimming and color mixing. For example, V C1 and V C2 may be set to three preset values, corresponding to the main light mode, the night light mode, and the mixed light mode, respectively. The first current control module 111 outputs different reference signals V C1 and V C2 according to the action of the switch S1, so as to adjust the current flowing through the LED lamp 103 and the LED lamp 104, so that in the main light mode, the LED lamp 103 is lit and reaches the maximum operating current, and the LED lamp 104 is turned off; in the night light mode, the LED lamp 103 is turned off, and the LED lamp 104 is lit and reaches the maximum operating current; in the mixed light mode, the LED lamp 103 and the LED lamp 104 are both lit, and the current flowing through the LED lamp 103 and the LED lamp 104 both reaches half of the maximum operating current, so as to realize three-segment dimming and color mixing of the LED lighting system.

[0040] Figure 2 A schematic circuit diagram of an LED lighting system according to a first embodiment of the present application is shown. 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.

[0041] An alternating current power supply 201 is connected to two alternating current input terminals of the rectifier bridge 202 via the dimmer 210. The alternating current power supply 201 may, for example, adopt a commercial alternating current power supply or a UPS power supply. The alternating current power supply 201 provides an alternating current supply voltage V AC , for example, the alternating current supply voltage V AC is a sinusoidal alternating voltage of a rated frequency (also referred to as “power frequency”) of 50 Hz. The rectifier bridge 202 rectifies the alternating current input voltage to obtain a direct current input voltage V BUS .

[0042] The dimmer 210 includes a switch S1, and the LED lighting system 200 provides three outputs, namely the LED lamp 203, the LED lamp 204, and the LED lamp 205. In some embodiments, the LED lamp 203 and the LED lamp 204 have different color temperatures, for example, the LED lamp 203 is a cool light lamp, and the LED lamp 204 is a warm light lamp.

[0043] The first driving unit 220 and the second driving unit 230 are connected to the rectifier bridge 202 in sequence, the first driving unit 220 adjusts the current flowing through the LED lamp 203 and the LED lamp 204 according to the user switch action to adjust the color temperature of the LED lamp, and provides comfortable light. The second driving unit 230 adjusts the current flowing through the LED lamp 205 according to the working state of the LED lamp 203 to provide power supplement, thereby improving the output power of the overall lighting system and meeting the requirements of high-power and high-luminous flux occasions.

[0044] In some embodiments, the user can 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 the maximum working current and the LED lamp 204 is turned off, the LED lamp 205 is turned on, and the total load current of the lighting system is maximum. When the LED lamp 203 is turned off and the LED lamp 204 reaches the maximum working current, the LED lamp 205 is turned off, and the total load current of the lighting system is minimum. In this way, the brightness of the LED lighting system 200 is adjusted.

[0045] The circuit structure and working principle of the first driving unit 220 in the LED lighting system according to the present embodiment are basically the same as those of the first driving unit 110 used in the prior art shown in Figure 1 , and the detailed description thereof is omitted here.

[0046] With reference to Figure 2 , the second driving unit 230 includes a power module 231, a resistor R3, and a sampling and filtering module 232. Further, the sampling and filtering module 232 includes resistors R4 and R5 and a capacitor C O . The resistor R4 and the resistor R5 are connected in series between the negative terminal of the LED lamp 203 and the second DC output terminal of the rectifier bridge 202, and the capacitor C O is connected in parallel with the resistor R5 as a filtering circuit. The resistor R3 is connected between the power module 231 and the intermediate node of the resistors R4 and R5.

[0047] Because the forward voltage of the LED lamp group behaves differently in the on / off state (i.e., the on / off state), the negative terminal voltages V LED1 and V LED2 of the LED lamp 203 and the LED lamp 204 will exhibit obvious differences in different working states. For example, when the LED lamp 203 is turned off, the current I LED1 is 0, and V LED1 is high. When the LED lamp 203 is turned on, the current I LED1 is not 0, and V LED1 is low. The resistors R4 and R5 sample the negative terminal voltage V LED1 of the LED lamp 203, and the capacitor C OAfter filtering, the sampled signal V representing the working state of LED 203 is obtained. FB .

[0048] See Figure 3 The power supplement module 231 includes a second current control module 2311, an operational amplifier U3, a transistor M3, and a resistor R6. The LED 205, transistor M3, and resistor R6 are connected in series between the first and second DC output terminals of the rectifier bridge 202. Transistor M3 controls the current flowing through the LED 205 (i.e., current I). LED3 Resistor R6 is used to obtain the sampling current V of LED 205. CS3 The first input terminal of the second current control module 2311 is connected to resistor R3, and the sampling signal V... FB The current is input to the second current control module 2311 after passing through resistor R3. The second input terminal of the second current module 2311 is connected to the negative terminal of LED 205. The first output terminal of the second current control module 2311 is connected to the non-inverting input terminal of operational amplifier U3, and the current is controlled according to the sampled signal V. FB Output reference signal V C3 It is 0 or a preset value, for example, when the sampled signal V FB When the value is less than the threshold, output the reference signal V. C3 This is a preset value; when the sampled signal V FB When the threshold is reached, output the reference signal V. C3 The value is 0. The inverting input of operational amplifier U3 is connected to the intermediate node of transistor M3 and resistor R6, receiving the sampled current signal V. CS3 Operational amplifier U3 is based on the reference signal V C3 and sampled current signal V CS3 Output drive signal V G3 The current I flowing through LED 205 is adjusted by regulating transistor M3. LED3 Furthermore, the reference signal V can be adjusted by changing the resistance value of resistor R3. C3 The preset value is used to adjust the peak current of the power module 231.

[0049] Furthermore, in this embodiment, the second current control module 2311 also includes a concave unit (not shown in the figure) to generate a reference signal V with a concave waveform. C3 Thus, a load current I with a concave waveform is obtained. LED3 This is beneficial to improving the working efficiency of the second drive unit 231.

[0050] See Figure 4 The sampling filter module 232 can be equivalently represented by connecting V in series between resistor R3 and the second DC input terminal of rectifier bridge 202. FBVoltage signal. Because the positive voltage of the LED group behaves differently in the on / off state (i.e., lit / off state), the negative terminal voltage V of LEDs 203 and 204 is affected. LED1 and V LED2 The voltage will also show a significant difference; for example, when LED 203 is lit, V LED1 Lower; when LED 203 is off, V LED1 High. In some embodiments, when the LED 203 is off, the current I flowing through the LED 203 is relatively high. LED1 The sampled signal V is 0. FB When the current rises to the threshold, the second current control module outputs a reference signal V. C3 It is 0, thus making I LED3 The voltage is 0, meaning the second driving unit 230 is off. When LED 203 lights up, the current flowing through LED 203 gradually increases, and the negative terminal voltage V of LED 203... LED1 Gradually decrease, reference signal V FB As the current decreases, the second current control module outputs a reference signal V. C3 The preset value is used to ensure that the current I flowing through the third LED group 205 is... LED3 The output power of the overall lighting system is gradually increased, with the second drive unit 230 providing supplementary power to meet the needs of high-power, high-luminous-flux applications.

[0051] Figure 5 A schematic circuit diagram of an LED lighting system according to a second embodiment of the present invention is shown. The LED lighting system 300 includes a dimmer 310, a rectifier bridge 302, a first driving unit 320, a second driving unit 330, LED lamps 303, 304, and 305, and a discharge circuit 306.

[0052] and Figure 3 The LED lighting system 200 of the first embodiment of the present invention differs in that the dimmer 310 of the LED lighting system 300 includes a switch S1 and a silicon controlled rectifier (SCR) dimmer 311. Correspondingly, the LED lighting system 300 also includes a bleeder circuit 306 connected between the first DC output terminal and the second DC output terminal of the rectifier bridge 302. Through the dimming action of the SCR dimmer 311, the conduction angle of the SCR can be changed, thus affecting the AC power supply voltage V. AC Chopping is performed to obtain the phase-cut AC input voltage V. CUT Relative to AC power supply voltage V AC In terms of V CUTThe effective voltage of the thyristor is related to the conduction angle of the thyristor, and thus the dimming action of the thyristor dimmer 311 can change the brightness of the LED lighting system, making the dimmed light more stable. Correspondingly, the LED lighting system further comprises a bleeder circuit 306, which can maintain the load current of the thyristor at a level greater than the holding current of the thyristor to solve the problem of LED flicker and limited dimming range caused by the thyristor turning off too early due to too small load current of the thyristor.

[0053] Figure 6 The working waveform diagram of the LED lighting system 300 is shown. Figure 5 The LED lighting system comprises a main light mode, a night light mode and a mixed light mode, taking three-section color adjustment as an example. As shown in the figure, V LED1 and V LED2 represent the voltages at the negative terminals of the LED lamp 303 and the LED lamp 304 respectively, I LED1 represents the current flowing through the LED lamp 303, I LED2 represents the current flowing through the LED lamp 304, and I LED3 represents the current flowing through the LED lamp 305, and the switching times are used to segmentally adjust the color temperature of the LED lighting system. In the main light mode, the LED lamp 303 is on and I LED1 is the maximum working current I1 of the LED lamp 303, and the LED lamp 304 is off, at which time the negative terminal voltage of the LED lamp 303 is low, so that the sampling signal V FB is low, and the second current control module outputs the reference signal V C3 at a preset value so that the power module 231 outputs the power supplement current I LED3 with a concave waveform; in the mixed light mode, the LED lamp 303 and the LED lamp 304 are both on, and I LED1 is 1 / 2I1, and I LED2 is 1 / 2I2 (I1 is the maximum working current of the LED lamp 303, and I2 is the maximum working current of the LED lamp 304), at which time the negative terminal voltage of the LED lamp 303 is low, and the second current control module still outputs the reference signal V C3 at a preset value so that the power module 231 outputs the power supplement current I LED3 with a concave waveform; in the night light mode, the LED lamp 304 is on and I LED2 is the maximum working current I2 of the LED lamp 304, and the LED lamp 303 is off, at which time V FB reaches a threshold value, the second current control module outputs the reference signal V C3 at 0, so that I LED3 is 0, and the second driving unit is turned off.

[0054] In accordance with the practices of the present invention, these embodiments have been described in relation to the above-described embodiments, which are intended to be illustrative only and not restrictive of the invention. Obviously, many modifications and variations of this invention can be effected without departing from the scope of the novel concept of the progression of the invention. No limitation with respect to the specific implementation of the present invention is intended or implied. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. It is intended that the patent be construed as including all such modifications and variations.

Claims

1. A multi-channel LED driving circuit for providing respective driving currents to a plurality of channels of LED lamps, the driving circuit comprising: a first driving unit for providing a first driving current to a first channel of LED and a second driving current to a second channel of LED, wherein the first driving unit comprises: a first current control module for adjusting a first reference signal and a second reference signal according to a dimming signal; a first branch connected in series with the first channel of LED between a first output and a second output of a rectifier bridge for adjusting the first driving current according to the first reference signal; and a second branch connected in series with the second channel of LED between the first output and the second output for adjusting the second driving current according to the second reference signal, the driving circuit further comprising: a second driving unit connected in series with a third channel of LED between the first output and the second output for providing a third driving current to the third channel of LED, the second driving unit being connected with the first branch to obtain a first sampling signal, wherein the first sampling signal represents an operating state of the first channel of LED, the second driving unit adjusts the third driving current according to the first sampling signal, when the first sampling signal represents that the first channel of LED is on, the second driving unit drives the third channel of LED to be on, and when the first sampling signal represents that the first channel of LED is off, the second driving unit drives the third channel of LED to be off.

2. The drive circuit of claim 1, wherein, The second driving unit further adjusts a magnitude of the third driving current according to the first sampling signal.

3. The drive circuit of claim 1, wherein, A maximum value of the first reference signal is greater than a maximum value of the second reference signal.

4. The drive circuit of claim 1, wherein, The first sampling signal is obtained by sampling a negative terminal voltage of the first channel of LED.

5. The drive circuit of claim 1, wherein, The first branch comprises: a first operational amplifier for 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 comprises: a second operational amplifier for outputting a second driving signal according to the second reference signal; and a second transistor for adjusting the second driving current according to the second driving signal.

6. The drive circuit of claim 1, wherein, The first current control module adjusting the first reference signal and the second reference signal according to the dimming signal comprises: adjusting the first reference signal to a maximum value and the second reference signal to zero, so that the first driving current is a first maximum operating current and the second driving current is zero; adjusting the second reference signal to a maximum value and the first reference signal to zero, so that the second driving current is a second maximum operating current and the first driving current is zero; adjusting the first reference signal to half of a maximum value and the second reference signal to half of a maximum value, so that the first driving current is half of a first maximum operating current and the second driving current is half of a second maximum operating current.

7. The drive circuit of claim 1, wherein, The second driving unit comprises: The power module comprises a first input end and a first output end, 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 as to adjust the third driving current.

8. The drive circuit of claim 7, wherein, The value of the third reference signal is a preset fixed value.

9. The drive circuit of claim 7, wherein, The second driving unit comprises a first resistor connected between the sampling filter module and the power module, wherein the third reference signal is adjusted by adjusting the resistance value of the first resistor.

10. The drive circuit of claim 7, wherein, The power module comprises: The second current control module is used for generating the third reference signal according to the first sampling signal; The third operational amplifier outputs a third driving signal according to the third reference signal; and The third transistor adjusts the third driving current according to the third driving signal.

11. The drive circuit of claim 10, wherein, The second current control module comprises a concave unit for generating the third reference signal with a concave waveform.

12. The drive circuit of claim 1, wherein, The LED of the first channel has a different color temperature from the LED of the second channel.

13. An LED lighting system, comprising: an LED lamp as a light source; a dimmer for adjusting the LED lamp current according to a dimming action, a rectifier bridge connected with the dimmer for rectifying an alternating input voltage to generate a direct current input voltage; and According to any one of claims 1 to 12, wherein the LED lamp and the driving circuit are connected in series between the first output end and the second output end of the rectifier bridge. The dimmer comprises a switch dimmer and / or a thyristor dimmer.

14. The lighting system of claim 13, wherein, ​

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