Dimming control circuit and LED lighting device

Abstract

The application relates to a dimming control circuit and an LED lighting device; the dimming control circuit comprises a discharging branch, a charging branch, an energy storage unit and a control unit; the discharging branch, the energy storage unit and a load are sequentially connected to form a discharging loop, and a power supply, the load, the energy storage unit and the charging branch are sequentially connected to form a charging loop. In the dimming control circuit, the charging loop and the discharging loop are arranged, the control unit controls the charging loop and the discharging loop to be alternately conducted, and the energy storage unit alternately charges and discharges; the control unit acquires a dimming signal, a first current signal and a second current signal, generates a control signal after logically processing the signals, and controls the time when the two loops are disconnected and conducted, so that the peak current on the energy storage unit and the off time T off two parameters are adjusted, so that the average current value on the energy storage unit is more accurately adjusted, and the dimming depth and dimming accuracy of the control circuit are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED intelligent dimming, in particular to a dimming control circuit and an LED lighting device. BACKGROUND

[0002] An LED light source is a light source based on a light-emitting diode, which has the advantages of using a low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no environmental pollution, multi-color light emission, etc. With the continuous development of LED technology, LED light sources have been widely applied. A large number of LED light sources are used as lighting or decoration in scenes such as shopping malls, factories, and houses, and the brightness of these LED light sources is adjusted when needed. With the application of the global market of LED lighting, special lighting such as stage lights, projection backlights, and smart home lighting has higher and higher requirements for dimming precision and dimming depth.

[0003] At present, the driving mode of the LED light source is mainly DCM (Discontinuous Conduction Mode). In the dimming mode of DCM, the inductor current is appropriately reset in a light-emitting period. When the power switch is closed, the inductor current is zero.

[0004] In related technologies, the dimming schemes on the market have the problems of insufficient dimming depth and low dimming precision, which cannot meet the user's needs in many scenes. SUMMARY

[0005] To at least partially overcome the problems in the related art, the present application provides a dimming control circuit and an LED lighting device.

[0006] According to a first aspect of an embodiment of the present application, a dimming control circuit is provided, comprising: a discharging branch, a charging branch, an energy storage unit, and a control unit;

[0007] The positive input end and the negative input end of the dimming control circuit are used to connect a power supply, and the positive output end and the negative output end are used to connect a load;

[0008] The energy storage unit, the discharging branch, and the load are connected in sequence to form a discharging loop, and the discharging branch feeds back a first current signal when it is turned on to the control unit;

[0009] The power supply, the load, the energy storage unit, and the charging branch are connected in sequence to form a charging loop, and the charging branch feeds back a second current signal when it is turned on to the control unit;

[0010] The control unit is configured to acquire a dimming signal, and output a control signal according to the dimming signal, a first current signal and a second current signal, control the discharging branch and the charging branch to be alternately turned on or turned off, so as to adjust the peak current and the turn-off time T on the energy storage unit off .

[0011] Further, the discharging branch comprises a first current detection unit and a first switch unit; an input end of the first switch unit is connected with the energy storage unit, and an output end thereof is connected with one end of the first current detection unit; the other end of the first current detection unit is connected with a positive output end LED+;

[0012] The first current detection unit detects a first current signal on the discharging branch, and transmits the first current signal to the control unit;

[0013] The control unit is configured to control the first switch unit to be turned on or turned off.

[0014] Further, the charging branch comprises a second current detection unit and a second switch unit; an input end of the second switch unit is connected with the energy storage unit, and an output end thereof is connected with one end of the second current detection unit; the other end of the second current detection unit is connected with a negative input end VIN-;

[0015] The second current detection unit detects a second current signal on the charging branch, and transmits the second current signal to the control unit;

[0016] The control unit is configured to control the second switch unit to be turned on or turned off.

[0017] Further, the control unit is configured to perform the following control actions:

[0018] When the second current signal is less than the peak current, the control unit performs a first control action: controlling the second switch unit to be turned on, while controlling the first switch unit to be turned off;

[0019] When the second current signal rises to the peak current, the control unit performs a second control action: controlling the second switch unit to be turned off, while controlling the first switch unit to be turned on;

[0020] After the first current signal falls to zero, the control unit performs a third control action: controlling the second switch unit to maintain the turned-off state until the duration of the turned-off state of the second switch unit reaches the turn-off time T off .

[0021] Further, the energy storage unit is an inductor L1, the second switch unit is a switch tube Q2, and the second current detection unit is a resistor RCSL;

[0022] The positive input terminal VIN+ is connected with the positive output terminal LED+; one end of the inductor L1 is connected with the negative output terminal LED-, and the other end is connected with the drain of the switch tube Q2; the source of the switch tube Q2 is connected with one end of the resistor RCSL, and the other end of the resistor RCSL is connected with the negative input terminal VIN-;

[0023] One end of the resistor RCSL is connected with the control unit, and is used for transmitting the second current signal to the control unit.

[0024] Further, the first current detection unit is the resistor RCSH, and the first switch unit is the switch tube Q1.

[0025] One end of the inductor L1 is connected with the negative output terminal LED-, and the other end is connected with the source of the switch tube Q1; the drain of the switch tube Q1 is connected with one end of the resistor RCSH, and the other end of the resistor RCSH is connected with the positive output terminal LED+.

[0026] One end of the resistor RCSH is connected with the control unit, and is used for transmitting the first current signal to the control unit.

[0027] Further, the control unit comprises a first output terminal GATEP and a second output terminal GATEN; the first output terminal GATEP is connected with the gate of the switch tube Q1, and the second output terminal GATEN is connected with the gate of the switch tube Q2.

[0028] The control unit outputs two different control signals from the first output terminal GATEP and the second output terminal GATEN respectively, and controls the switch tube Q1 and the switch tube Q2 respectively.

[0029] Further, the control unit and the first switch unit are integrated in the same chip.

[0030] Further, the control unit and the second switch unit are integrated in the same chip.

[0031] According to the second aspect of the embodiments of the present application, an LED lighting device is provided, which comprises the dimming control circuit according to any one of the above embodiments.

[0032] The technical scheme provided by the embodiments of the present application has the following beneficial effects:

[0033] The dimming control circuit of the application is provided with a charging circuit and a discharging circuit, the charging circuit and the discharging circuit are controlled by a control unit to be turned on alternately, so that the energy storage unit is charged and discharged alternately; the control unit obtains a dimming signal, a first current signal and a second current signal, and generates a control signal after logical processing of the signals, to control the time of turning off and turning on of the two circuits, so that the peak current on the energy storage unit and the turn-off time T off of the two parameters are adjusted, so that the average current value on the energy storage unit is adjusted more accurately, and the dimming depth and dimming accuracy of the control circuit are improved.

[0034] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings incorporated in the specification and constituting a part of it illustrate embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0036] Figure 1 is a structural block diagram of a dimming control circuit according to an embodiment.

[0037] Figure 2 is a schematic diagram of an external MOS dimming control circuit according to an embodiment.

[0038] Figure 3 is a chip internal structural block diagram of a control unit according to an embodiment.

[0039] Figure 4 is a signal change timing diagram when the first stage is not dimmed according to an embodiment.

[0040] Figure 5 is a signal change timing diagram when the first stage does not enter DCM according to an embodiment.

[0041] Figure 6 is a signal change timing diagram after the second stage enters DCM according to an embodiment.

[0042] Figure 7 is a signal change timing diagram of a second stage fixed T off according to an embodiment.

[0043] Figure 8 is a schematic diagram of a built-in lower-end power MOS dimming control circuit according to an embodiment.

[0044] Figure 9 is a schematic diagram of a built-in upper-end power MOS dimming control circuit according to an embodiment.

[0045] Figure 10 is a schematic diagram of a dimming control circuit of an external MOS according to another embodiment. DETAILED DESCRIPTION

[0046] The exemplary embodiments will be described in detail herein below with reference to the drawings. In the following description, the same numbers refer to the same or similar elements unless otherwise represented. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples of control circuits consistent with some aspects of the present application as detailed in the appended claims.

[0047] Figure 1 is a structural block diagram of a dimming control circuit according to an exemplary embodiment. The control circuit includes a discharging branch 1, a charging branch 2, an energy storage unit 3, and a control unit 4. The dimming control circuit has a positive input terminal and a negative input terminal for connecting a power supply, and a positive output terminal and a negative output terminal for connecting a load.

[0048] The energy storage unit 3, the discharging branch 1, and the load are connected in sequence to form a discharging circuit, and the discharging branch 1 feeds back a first current signal when it is turned on to the control unit 4. The power supply, the load, the energy storage unit 3, and the charging branch 2 are connected in sequence to form a charging circuit, and the charging branch 2 feeds back a second current signal when it is turned on to the control unit 4.

[0049] The control unit 4 is configured to obtain a dimming signal, and output a control signal according to the dimming signal, the first current signal, and the second current signal, to control the discharging branch 1 and the charging branch 2 to be turned on or turned off alternately, so as to adjust a peak current and an off time T off on the energy storage unit 3.

[0050] The dimming control circuit of the present application has a charging circuit and a discharging circuit, and the control unit 4 controls the charging circuit and the discharging circuit to be turned on alternately, so that the energy storage unit 3 is charged and discharged alternately. The control unit 4 obtains the dimming signal, the first current signal, and the second current signal, and generates a control signal by logically processing these signals, to control the time when the two circuits are turned off and turned on. Thus, the peak current and the off time T off on the energy storage unit 3 can be adjusted, so that the average current value on the energy storage unit 3 can be adjusted more accurately, and the dimming depth and the dimming accuracy of the control circuit can be improved.

[0051] In order to make the objectives, technical solutions, and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0052] Referring to Figure 1 In some embodiments, the charging branch 2 comprises a second current detection unit 201 and a second switch unit 202; an input end of the second switch unit 202 is connected with the energy storage unit 3, and an output end thereof is connected with one end of the second current detection unit 201; the other end of the second current detection unit 201 is connected with the negative input end VIN-. The second current detection unit 201 detects a second current signal on the charging circuit and transmits the second current signal to the control unit 4. The control unit 4 is configured to control the second switch unit 202 to be turned on or turned off.

[0053] In actual application, the second switch unit 202 can adopt any type of electronic switch device, such as MOS (Metal-Oxide-Semiconductor Field-Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), triode, thyristor, etc., which can all realize the scheme of the present application. When the second switch unit 202 is turned on, the charging circuit starts to work, and the current flows from the positive input end VIN+ to the load, the energy storage unit 3, the second switch unit 202, the second current detection unit 201, and then back to the negative input end VIN-. At this time, the power supply supplies power to the load and charges the energy storage unit 3.

[0054] Referring to Figure 1 In some embodiments, the discharging branch 1 comprises a first current detection unit 101 and a first switch unit 102; an input end of the first switch unit 102 is connected with the energy storage unit 3, and an output end thereof is connected with one end of the first current detection unit 101; the other end of the first current detection unit 101 is connected with the positive output end LED+. The first current detection unit 101 detects a first current signal on the discharging circuit and transmits the first current signal to the control unit 4. The control unit 4 is configured to control the first switch unit 102 to be turned on or turned off.

[0055] In actual application, the first switch unit 102 can also adopt any type of electronic switch device, and is not limited to a specific type of device. When the first switch unit 102 is turned on, the discharging circuit starts to work, the energy storage unit 3 discharges, and the discharging current flows through the first switch unit 102, the first current detection unit 101 and the load in sequence; at this time, the energy storage unit 3 supplies power to the load.

[0056] Referring to Figure 2In some embodiments, the control unit 4 includes a first output terminal GATEP and a second output terminal GATEN; the first output terminal GATEP is connected to the gate of the switching transistor Q1, and the second output terminal GATEN is connected to the gate of the switching transistor Q2. The control unit 4 outputs two different control signals from the first output terminal GATEP and the second output terminal GATEN, respectively, to control the switching transistors Q1 and Q2.

[0057] like Figure 2 As shown, in some embodiments, the energy storage unit 3 is an inductor L1, the second switching unit 202 is a switching transistor Q2, and the second current detection unit 201 is a resistor RCSL. The positive input terminal VIN+ is connected to the positive output terminal LED+; one end of the inductor L1 is connected to the negative output terminal LED-, and the other end is connected to the drain of the switching transistor Q2; the source of the switching transistor Q2 is connected to one end of the resistor RCSL, and the other end of the resistor RCSL is connected to the negative input terminal VIN-. One end of the resistor RCSL is connected to the control unit 4 for transmitting a second current signal to the control unit 4.

[0058] Combination Figure 2 The dimming control circuit of this application operates as follows: After power-on, the GATEN pin of chip U1 first outputs a high level, the switching transistor Q2 is turned on, and the current flows from the positive input terminal VIN+ to the positive output terminal LED+, the negative output terminal LED-, the inductor L1, the switching transistor Q2, and the inductor peak current detection resistor RCSL, and then back to the negative input terminal VIN-. When the voltage across the inductor peak current detection resistor RCSL rises to the threshold voltage set internally by the chip, the switching transistor Q2 is turned off.

[0059] Reference Figure 2 In some embodiments, the first current detection unit 101 is a resistor RCSH, and the first switching unit 102 is a switching transistor Q1. One end of the inductor L1 is connected to the negative output terminal LED-, and the other end is connected to the source of the switching transistor Q1; the drain of the switching transistor Q1 is connected to one end of the resistor RCSH, and the other end of the resistor RCSH is connected to the positive output terminal LED+. One end of the resistor RCSH is connected to the control unit 4 for transmitting a first current signal to the control unit 4.

[0060] When the voltage on the inductance peak current detection resistor RCSL rises to the threshold voltage set in the chip, the switch tube Q2 is turned off, the chip GATEP outputs a high level, the switch tube Q1 is turned on, the inductance L1 is discharged, and the inductance L1, the switch tube Q1, the inductance valley current detection resistor RCSH, the positive output end LED+ and the negative output end LED- form a discharge circuit. When the inductance current decreases, the voltage on the RCSH decreases, and when it decreases to the threshold voltage set in the chip, the chip GATEP outputs a low level, the switch tube Q1 is turned off, the GATEN outputs a high level, and the switch tube Q2 is turned on. The above charging and discharging processes are alternately performed, and thus the regulation of the average current on the inductance L1 can be realized.

[0061] In some embodiments, the control unit 4 is configured to perform the following control actions:

[0062] When the second current signal is less than the peak current, the control unit 4 performs a first control action: controlling the second switch unit 202 to be turned on, while controlling the first switch unit 102 to be turned off;

[0063] When the second current signal rises to the peak current, the control unit 4 performs a second control action: controlling the second switch unit 202 to be turned off, while controlling the first switch unit 102 to be turned on;

[0064] After the first current signal decreases to zero, the control unit 4 performs a third control action: controlling the second switch unit 202 to maintain the off state until the duration of the second switch unit 202 in the off state reaches the turn-off time T off .

[0065] In the embodiments of the present application, the control unit 4 can have two different implementation schemes: the first scheme is that the control unit 4 adopts a processing chip such as an MCU (Microcontroller Unit), and the acquired signals are operated by the program in the chip to generate control signals; the second scheme is that a hardware circuit is built, and the collected signals are directly processed by the hardware circuit to generate control signals, for example, the hardware circuit as shown in Figure 3 can be used to realize the control actions of the present scheme.

[0066] Referring to Figure 3In some embodiments, the control unit 4 can include a signal conversion unit, a first comparator U2, a second comparator U3, a logic control unit, etc. The first comparator U2 obtains a first reference signal from a power supply voltage, compares the first reference signal with a first current signal, and generates a first comparison signal output to the logic control unit. The signal conversion unit is used to obtain a dimming signal and convert the dimming signal into a second reference signal; the second comparator U3 compares the second reference signal with a second current signal, and generates a second comparison signal output to the logic control unit. The logic control unit outputs a control signal according to the first comparison signal and the second comparison signal. Specifically, the dimming signal is usually a PWM signal; the signal conversion unit can include a PWM-to-voltage circuit and a clamping circuit; the PWM-to-voltage circuit converts the dimming signal into a voltage signal and transmits the voltage signal to the clamping circuit; and the clamping circuit generates the second reference signal after clamping the voltage signal.

[0067] To further detail the technical solutions of the present application, the technical principles of the present application will be explained in detail below in combination with the timing diagrams of various signals.

[0068] The dimming principle of the dimming control circuit of the present application: RCSL sets the inductor peak current, RCSH sets the inductor valley current, and simultaneously determines T off The initial value. The dimming signal input externally to the PWM pin of the chip enters the IC internally, is converted into a direct current voltage by a PWM voltage conversion module (time detection module and DAC), and the direct current voltage controls the dimming in two stages.

[0069] The signal change timing diagram of the first stage is shown in Figure 4 and Figure 5 , in which I L1 is the current size on the inductor L1, and GATEP and GATEN are the output signal levels of the two pins corresponding to the control unit 4. Figure 4 is the signal change timing diagram when no PWM signal is input. Figure 5 is the signal change timing diagram when the PWM signal is input but has not yet entered the DCM. It can be known in combination with Figure 3 that when the duty cycle of the PWM signal decreases from 100%, the direct current voltage converted internally in the chip also decreases, and the voltage controls the T off time to decrease through a voltage time module; therefore, as the duty cycle of the PWM signal decreases, the T off is prolonged, the discharge time of the inductor L1 is prolonged, and the valley current is significantly reduced (from I L1valley1 to I L1valley2 ); in this way, the current applied to the output LED by the circuit decreases until the longest T off limit (40 μs) set internally in the chip. It can be noted that in the first stage, the peak current does not change (I L1peak1With I L1peak2 The average current size is reduced by controlling the T off time extension (extending the inductance L1 discharge time) to reduce the average current size.

[0070] When the maximum T off limit (40μs) is reached, the internal voltage controlled by the PWM dimming signal is just 0.5V; if the duty cycle of the PWM signal continues to decrease, it enters the second stage, and the signal change timing diagram is shown in Figure 6 and Figure 7 . In combination with Figure 3 , the DC voltage converted by the PWM signal is used as the reference voltage of the internal comparator U3 of the CS-L pin; if the duty cycle of the PWM dimming signal continues to decrease, the time that the GATEN signal output by the control unit 4 is at high level becomes shorter, and the conduction time of the switch tube Q2 becomes shorter, thus reducing the peak current (from I L1peak3 to I L1peak4 ); thus the output current continues to decrease. It can be noted that in the second stage, the T off time has reached the limit and cannot continue to be extended; thus the peak current is controlled to decrease by shortening the conduction time of the switch tube Q2, so as to reduce the average current size.

[0071] As shown in Figure 8 , in some embodiments, the control unit 4 and the first switch unit 102 are integrated in the same chip. That is, the U1 chip shown in the figure integrates the lower power MOS and the control unit 4, and the CS-L pin of the U1 chip is the source of the internal lower power MOS of the chip, so that one end of the resistor RCSL is connected to the CS-L pin of the chip U1; the connection relationship of the other parts of the control circuit of the present embodiment is the same as that of the embodiments described above, and the present embodiment will not be described again.

[0072] As shown in Figure 9 , in some embodiments, the control unit 4 and the second switch unit 202 are integrated in the same chip. That is, the U1 chip shown in the figure integrates the upper power MOS and the control unit 4, and the CS-H pin of the U1 chip is the source of the internal upper power MOS of the chip, so that one end of the resistor RCSH is connected to the CS-H pin of the chip U1; the connection relationship of the other parts of the control circuit of the present embodiment is the same as that of the embodiments described above, and the present embodiment will not be described again.

[0073] As shown in Figure 10As shown, in some embodiments, the switch tube Q1 can adopt a P-MOS tube, the switch tube Q2 can adopt an N-MOS tube, and the dimming control function of the present solution can also be realized; the specific connection mode of the circuit is the same as that of the embodiments described above, and the present embodiment will not be described again.

[0074] The embodiments of the present application also provide an LED lighting device, which comprises a power supply, a dimming control circuit and an LED load; the power supply is connected between a positive input end VIN+ and a negative input end VIN- of the dimming control circuit, and the LED load is connected between a positive output end LED+ and a negative output end LED- of the dimming control circuit. The specific structure of the dimming control circuit is the same as that of any one of the dimming control circuits in the embodiments described above, and the present embodiment will not be described again.

[0075] The technical solutions of the above embodiments are adopted in the present application, and the following technical problems can be solved: 1. The dimming depth is not enough, and the theoretical minimum dimming depth of the present patent reaches 0.01%; 2. The dimming precision is not enough, and the theoretical minimum dimming precision of the present patent reaches 0.01%; 3. The stroboscopic problem, the present patent has no stroboscopic in the whole dimming process; 4. In the dimming process, when the brightness is less than 5%, there is stepwise jitter in continuous dimming; 5. When the dimming PWM frequency is lower than 20 kHz, there is audible audio noise; 6. When the input voltage ripple is large, the machine is misoperated; 7. The EMI filter is complex, and the cost is high.

[0076] It can be understood that the same or similar parts in the above embodiments can be mutually referred to, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0077] It should be noted that, in the description of the present application, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is at least two.

[0078] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0079] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A dimming control circuit, characterized by, The application relates to a dimming control circuit. The dimming control circuit comprises a discharging branch (1), a charging branch (2), an energy storage unit (3) and a control unit (4). The dimming control circuit comprises a discharging branch (1), a charging branch (2), an energy storage unit (3) and a control unit (4). The energy storage unit (3), the discharging branch (1) and the load are sequentially connected to form a discharging loop, and the discharging branch (1) feeds back a first current signal when the discharging branch (1) is turned on to the control unit (4). The energy storage unit (3), the discharging branch (2) and the load are sequentially connected to form a charging loop, and the charging branch (2) feeds back a second current signal when the charging branch (2) is turned on to the control unit (4). The control unit (4) is configured to acquire a dimming signal, and output a control signal according to the dimming signal, a first current signal and a second current signal, and control the discharging branch (1) and the charging branch (2) to be alternately turned on or turned off, so as to adjust the peak current and the turn-off time T of the energy storage unit (3) off ; The discharging branch (1) comprises a first current detection unit (101) and a first switch unit (102); the input end of the first switch unit (102) is connected with the energy storage unit (3), the output end is connected with one end of the first current detection unit (101); the other end of the first current detection unit (101) is connected with the positive output end LED+. The first current detection unit (101) detects the first current signal on the discharging loop and transmits the first current signal to the control unit (4). The control unit (4) is used for controlling the first switch unit (102) to be turned on or turned off. The charging branch (2) comprises a second current detection unit (201) and a second switch unit (202); the input end of the second switch unit (202) is connected with the energy storage unit (3), the output end is connected with one end of the second current detection unit (201); the other end of the second current detection unit (201) is connected with the negative input end VIN-. The second current detection unit (201) detects the second current signal on the charging loop and transmits the second current signal to the control unit (4). The control unit (4) is used for controlling the second switch unit (202) to be turned on or turned off. The control unit (4) is used for performing the following control actions: When the second current signal is smaller than the peak current, the control unit (4) performs the first control action: controlling the second switch unit (202) to be turned on and simultaneously controlling the first switch unit (102) to be turned off; When the second current signal rises to the peak current, the control unit (4) performs the second control action: controlling the second switch unit (202) to be turned off and simultaneously controlling the first switch unit (102) to be turned on. After the first current signal falls to zero, the control unit (4) performs a third control action: controlling the second switching unit (202) to maintain the open state until the duration that the second switching unit (202) is in the open state reaches the off time T off .

2. The dimming control circuit of claim 1, wherein, The energy storage unit (3) is an inductor L1, the second switch unit (202) is a switch tube Q2, and the second current detection unit (201) is a resistor RCSL. The positive input end VIN+ is connected with the positive output end LED+, one end of the inductor L1 is connected with the negative output end LED-, the other end of the inductor L1 is connected with the drain of the switch tube Q2, the source of the switch tube Q2 is connected with one end of the resistor RCSL, and the other end of the resistor RCSL is connected with the negative input end VIN-. One end of the resistor RCSL is connected with the control unit (4) and is used for transmitting the second current signal to the control unit (4).

3. The dimming control circuit of claim 2, wherein, The first current detection unit (101) is a resistor RCSH, and the first switch unit (102) is a switch tube Q1; One end of the inductor L1 is connected to a negative output end LED-, and the other end is connected to a source of the switch tube Q1; a drain of the switch tube Q1 is connected to one end of the resistor RCSH, and the other end of the resistor RCSH is connected to a positive output end LED+. One end of the resistor RCSH is connected to the control unit (4) and used for transmitting a first current signal to the control unit (4).

4. The dimming control circuit of claim 3, wherein, The control unit (4) comprises a first output end GATEP and a second output end GATEN; the first output end GATEP is connected to a gate of the switch tube Q1, and the second output end GATEN is connected to a gate of the switch tube Q2. The control unit (4) outputs two different control signals from the first output end GATEP and the second output end GATEN respectively, and controls the switch tube Q1 and the switch tube Q2 respectively.

5. The dimming control circuit of any one of claims 1-4, wherein: The control unit (4) and the first switch unit (102) are integrated in the same chip.

6. The dimming control circuit of any one of claims 1-4, wherein: The control unit (4) and the second switch unit (202) are integrated in the same chip.

7. An LED lighting device, characterized by The dimming control circuit comprises the dimming control circuit according to any one of claims 1-6.

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