LED driving control circuit, control method thereof, and LED driving system

Abstract

The application provides an LED driving control circuit, a control method thereof and an LED driving system. The LED driving control circuit comprises a first loop compensation circuit, a reference signal generation circuit, an adjusting circuit and a first operational amplifier circuit. The first loop compensation circuit is configured to generate a first loop compensation signal according to a first detection signal. A first input end of the reference signal generation circuit is coupled with the first loop compensation circuit. A first input end of the adjusting circuit receives a current threshold, and a second input end of the adjusting circuit is coupled with the reference signal generation circuit. A first input end of the first operational amplifier circuit is coupled with the reference signal generation circuit, a second input end of the first operational amplifier circuit receives a first current sampling signal representing an output capacitor charging current, and an output end of the first operational amplifier circuit is coupled with a first transistor. The LED driving control circuit, the control method thereof and the LED driving system can effectively reduce the power consumption of the control circuit and improve the system efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics and relates to an LED driving technology, in particular to an LED driving control circuit and a control method thereof and an LED driving system. Background Art

[0002] Linear LED driver systems are widely used due to their relatively simple circuit structure. However, their output current is a square wave, which can cause flicker at the power frequency. To eliminate this flicker, improve current controllability, and enhance the efficiency of linear LED driver systems, it is necessary to control the output capacitor charging current and perform power compensation on this current while ensuring that the power factor (PF) meets the required requirements.

[0003] like Figure 1 Figure 2 shows a typical circuit structure diagram of a linear LED driver system. The linear LED driver system includes a charging control circuit and an output current control circuit. The charging control circuit is used to control the charging current of the output capacitor (i.e., first capacitor C1), while the output current control circuit is used to control the current flowing through the LED load. A detection circuit is used to sample a voltage Vdl at one of the load terminals. The loop control circuit is coupled to the detection circuit to obtain the terminal voltage Vdl. The loop control circuit uses the terminal voltage Vdl to determine whether the LED driver system has sufficient voltage margin for constant-current output control of the LEDs. This generates a suitable compensation signal COMP as a reference to control the charging current of the output capacitor C1, thereby maintaining a sufficiently low terminal voltage Vdl to improve the efficiency of the LED driver system.

[0004] In such Figure 2 In the illustrated technical solution, to reduce chip power consumption, the reference signal during the charging phase of output capacitor C1 is processed, resulting in a waveform with a low center and high edges for the output capacitor charging current Icap, effectively reducing transistor losses. However, in the prior art, the compensation signal COMP varies based on factors such as the high voltage HV, the LED load voltage, and the current flowing through the LED load. This can cause the charging current Icap to drop too low, reaching the set minimum value, thereby clamping the valley current. Furthermore, insufficient compensation can occur, resulting in a weaker concave portion of the charging current Icap waveform, which can fail to achieve the desired system efficiency.

[0005] In view of this, it is necessary to provide a new structure or control method to solve at least part of the above problems. Summary of the Invention

[0006] In response to one or more problems in the prior art, the present invention provides an LED drive control circuit and a control method thereof, and an LED drive system.

[0007] According to one aspect of the present application, there is disclosed an LED driving control circuit, comprising:

[0008] a first loop compensation circuit having an input terminal receiving a first detection signal representing an end voltage of a load, for generating a first loop compensation signal according to the first detection signal;

[0009] a reference signal generating circuit having a first input terminal coupled to the first loop compensation circuit, for generating a first reference signal according to the first loop compensation signal;

[0010] an adjustment circuit having a first input terminal receiving a current threshold and a second input terminal coupled to an output terminal of the reference signal generating circuit, for generating an adjustment signal according to the current threshold and the first reference signal to adjust the first reference signal; and

[0011] a first operational amplifier circuit having a first input terminal coupled to the reference signal generating circuit and a second input terminal receiving a first current sampling signal representing an output capacitor charging current, and having an output terminal coupled to the first transistor.

[0012] In one embodiment, the adjustment circuit comprises:

[0013] a voltage obtaining circuit having an input terminal receiving the first detection signal or an end voltage of one end of the output capacitor as a second detection signal;

[0014] a second loop compensation circuit having a first input terminal receiving the first reference signal and a second input terminal receiving the current threshold, for generating a second loop compensation signal according to the first reference signal and the current threshold; and

[0015] an adjustment signal generating circuit having input terminals coupled to the voltage obtaining circuit and the second loop compensation circuit respectively, for generating the adjustment signal according to the second detection signal and the second loop compensation signal.

[0016] In one embodiment, when the first reference signal is greater than the current threshold, the adjustment circuit adjusts the second loop compensation signal to decrease the first reference signal; and when the first reference signal is less than the current threshold, the adjustment circuit adjusts the second loop compensation signal to increase the first reference signal.

[0017] In one embodiment, the adjustment circuit further comprises a multiplier having a first input terminal coupled to the voltage obtaining circuit, a second input terminal coupled to the second loop compensation circuit, and an output terminal coupled to the adjustment signal generating circuit.

[0018] In one embodiment, the reference signal generating circuit comprises an operational circuit having a first input terminal coupled to an output terminal of the first loop compensation circuit, a second input terminal coupled to an output terminal of the adjustment circuit, and an output terminal coupled to a first input terminal of the first operational amplifier circuit.

[0019] In one embodiment, the current threshold is a preset fixed value, or the current threshold is 1 / k1 times of the first loop compensation signal, where k1>1.

[0020] In one embodiment, when the first reference signal is greater than the current threshold, the compensation capacitor in the adjustment circuit is charged; when the first reference signal is less than the current threshold, the compensation capacitor in the adjustment circuit is discharged, where the discharging speed is greater than the charging speed.

[0021] According to another aspect of the present application, there is disclosed an LED driving system comprising the LED driving control circuit as claimed in any one of the above.

[0022] According to yet another aspect of the present application, there is disclosed an LED driving control method for controlling a charging current of an output capacitor in an LED driving system, the LED driving control method comprising:

[0023] receiving a first detection signal representing an end voltage of the load, and generating a first loop compensation signal according to the first detection signal;

[0024] generating a first reference signal according to the first loop compensation signal;

[0025] generating an adjustment signal according to a current threshold and the first reference signal to adjust the first reference signal; and

[0026] controlling the first transistor to control the charging current of the output capacitor according to the first reference signal and a first current sampling signal representing the charging current of the output capacitor.

[0027] In one embodiment, the LED driving control method further comprises:

[0028] receiving an end voltage of one of the first detection signal or the output capacitor as a second detection signal;

[0029] generating a second loop compensation signal according to the first reference signal and the current threshold; and

[0030] generating the adjustment signal according to the second detection signal and the second loop compensation signal.

[0031] In one embodiment, when the first reference signal is greater than the current threshold, the second loop compensation signal is adjusted to lower the first reference signal; when the first reference signal is less than the current threshold, the second loop compensation signal is adjusted to increase the first reference signal.

[0032] The present invention provides an LED driver control circuit, a control method thereof, and an LED driver system. The LED driver control circuit includes a first loop compensation circuit, a reference signal generation circuit, a regulation circuit, and a first operational amplifier circuit. The first loop compensation circuit receives a first detection signal representing a load terminal voltage at its input, and is configured to generate a first loop compensation signal based on the first detection signal. A first input of the reference signal generation circuit is coupled to the first loop compensation circuit, and is configured to generate a first reference signal based on the first loop compensation signal. A first input of the regulation circuit receives a current threshold, and a second input of the regulation circuit is coupled to the output of the reference signal generation circuit. The regulation circuit generates a regulation signal based on the current threshold and the first reference signal to regulate the first reference signal. A first input of the first operational amplifier circuit is coupled to the reference signal generation circuit, and a second input of the first operational amplifier circuit receives a first current sampling signal representing an output capacitor charging current. The output of the first operational amplifier circuit is coupled to a first transistor. The LED driver control circuit, control method thereof, and LED driver system proposed in the present invention can effectively reduce power consumption of the control circuit and improve system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and, together with the description, to explain the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 A circuit structure diagram of an LED driving system in the prior art is shown;

[0035] Figure 2 A schematic diagram showing waveforms of signals in an LED driving system of the prior art is shown;

[0036] Figure 3 A schematic diagram of the circuit structure of an LED driving system according to an embodiment of the present invention is shown;

[0037] Figure 4 FIG2 shows a schematic diagram of a circuit structure of a regulating circuit according to an embodiment of the present invention;

[0038] Figure 5 FIG. 1 is a schematic diagram showing waveforms of signals in an LED driving system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0040] The description of this part is only for several typical embodiments, and the application is not limited to the scope of the embodiment description. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of the same or similar prior art means and some technical features in the embodiments are also within the description and protection scope of the application.

[0041] In the specification, "coupling" or "connection" includes both direct connection and indirect connection. Indirect connection is the connection through intermediate medium, such as the connection through electrically conductive medium such as conductor, wherein the electrically conductive medium can contain parasitic inductance or parasitic capacitance, or the connection through intermediate circuit or component described in the embodiments of the specification; indirect connection can also include the connection through other active devices or passive devices on the basis of realizing the same or similar functions, such as the connection through switch, signal amplification circuit, follow-up circuit and other circuits or components. "Multiple" or "many" means two or more. In addition, in the application, words such as first, second and the like are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship or order between the technical features.

[0042] An embodiment of the application discloses an LED drive control circuit, as shown in Figure 3 The LED drive control circuit includes a first loop compensation circuit 12, a reference signal generation circuit 13, an adjusting circuit 15 and a first operational amplifier circuit 14. The input end of the first loop compensation circuit 12 receives a first detection signal representing the terminal voltage of the load, and the first loop compensation circuit 12 is used to generate a first loop compensation signal according to the first detection signal. In an embodiment, the first detection signal can be obtained through the terminal voltage of one end of the high-voltage side of the load. In another embodiment, the first detection signal can also be obtained through the terminal voltage of one end of the low-voltage side of the load. Continue to refer to Figure 3The first input terminal of the reference signal generating circuit 13 is coupled to the output terminal of the first loop compensation circuit 12. The reference signal generating circuit 13 is used to generate a first reference signal Vref based on the first loop compensation signal COMP1. The first input terminal of the adjustment circuit 15 receives the current threshold CSmin. The second input terminal of the adjustment circuit 15 is coupled to the output terminal of the reference signal generating circuit 13. The output terminal of the adjustment circuit 15 is coupled to the second input terminal of the reference signal generating circuit 13. The adjustment circuit is used to generate an adjustment signal based on the current threshold CSmin and the first reference signal Vref to adjust the first reference signal Vref. The first input terminal of the first operational amplifier circuit 14 is coupled to the output terminal of the reference signal generating circuit 13. The second input terminal of the first operational amplifier circuit 14 receives a first current sampling signal representing the charging current of the output capacitor C1. The output terminal of the first operational amplifier circuit 14 is coupled to the first transistor Q1 to control the charging current of the output capacitor C1. In one embodiment, the first operational amplifier circuit is a first operational amplifier, wherein a non-inverting input of the first operational amplifier is coupled to an output of a reference signal generating circuit, an inverting input of the first operational amplifier receives a first current sampling signal, and an output of the first operational amplifier is coupled to a first transistor Q1. The first operational amplifier outputs a signal to drive the first transistor Q1, thereby controlling the charging current of the output capacitor C1. In the present invention, by adjusting the compensation level based on a comparison result between a current threshold and a first reference signal, the power consumption of the control circuit can be effectively reduced, system efficiency can be improved, and stable circuit operation can be ensured.

[0043] In another embodiment, the LED drive control circuit further includes a voltage detection circuit 11. An input terminal of the voltage detection circuit 11 is coupled to one terminal of the LED load to obtain a first detection signal. An input terminal of the first loop compensation circuit 12 is coupled to an output terminal of the voltage detection circuit 11 to obtain the first detection signal. In one embodiment, the input terminal of the voltage detection circuit is coupled to a high voltage terminal of the LED load to obtain a high voltage voltage HV. In this case, the high voltage voltage HV can serve as the first detection signal. In another embodiment, the input terminal of the voltage detection circuit 11 is coupled to a low voltage terminal of the LED load to obtain the first detection signal Vdl.

[0044] like Figure 4 As shown in FIG. 1 , in one embodiment of the present invention, the regulating circuit 15 includes a voltage acquisition circuit 151, a second loop compensation circuit 152, a multiplier 153, and a regulating signal generating circuit 154. The input end of the voltage acquisition circuit 151 receives the first detection signal or the terminal voltage of one end of the output capacitor as the second detection signal. Figure 4In the shown embodiment, the input of the voltage acquisition circuit 151 receives the terminal voltage Vdc of the low voltage side of the output capacitor C1 as the second detection signal. The first input of the second loop compensation circuit 152 receives the first reference signal Vref, and the second input of the second loop compensation circuit 152 receives the current threshold CSmin, and the second loop compensation circuit 152 is configured to generate a second loop compensation signal COMP2 according to the first reference signal Vref and the current threshold CSmin. The first input of the multiplier 153 is coupled to the output of the voltage acquisition circuit 151, and the second input of the multiplier 153 is coupled to the second loop compensation circuit 152. The input of the adjustment signal generation circuit 154 is coupled to the output of the multiplier 153, and the adjustment signal generation circuit 154 is configured to generate an adjustment signal according to the second detection signal and the second loop compensation signal to adjust the first reference signal Vref.

[0045] In an embodiment of the present application, when the first reference signal Vref is greater than the current threshold CSmin, the adjustment circuit 15 adjusts the second loop compensation signal COMP2 to reduce the first reference signal Vref; when the first reference signal Vref is less than the current threshold CSmin, the adjustment circuit 15 adjusts the second loop compensation signal COMP2 to increase the first reference signal Vref. In a specific embodiment of the present application, the current threshold is a preset fixed value, or the current threshold is 1 / k1 times the first loop compensation signal, where k1>1.

[0046] In another embodiment of the present application, the reference signal generation circuit 13 includes an operation circuit, which is a subtractor, the first input of the subtractor is coupled to the output of the first loop compensation circuit 12, the second input of the subtractor is coupled to the output of the adjustment circuit, and the output of the subtractor is coupled to the first input of the first operation amplifier circuit. The first reference signal Vref generated by the reference signal generation circuit is equal to COMP1-k2*Vdc, where COMP1 is the first loop compensation signal, k2 is the second loop compensation signal COMP2 output by the second loop compensation circuit 152, k2>0, and Vdc is the second detection signal, which in this embodiment can be the terminal voltage of the low voltage side of the output capacitor C1. The size of k2 can be controlled by the comparison result of the first reference signal Vref and the current threshold CSmin, so as to adjust the first reference signal Vref. When the first reference signal Vref is greater than the current threshold CSmin, the adjustment circuit 15 controls to increase the second loop compensation signal COMP2 to reduce the first reference signal Vref; when the first reference signal Vref is less than the current threshold CSmin, the adjustment circuit 15 controls to reduce the second loop compensation signal COMP2 to increase the first reference signal Vref.

[0047] In another embodiment of the present invention, the reference signal generation circuit 13 includes an operational circuit, which is an adder. A first input of the adder is coupled to the output of the first loop compensation circuit 12, a second input of the adder is coupled to the output of the regulation circuit, and the output of the adder is coupled to the first input of the first operational amplifier circuit. The reference signal generation circuit generates a first reference signal Vref equal to COMP1+(-k3)*Vdc, where COMP1 is the first loop compensation signal, k3 is the second loop compensation signal output by the second loop compensation circuit 152, k3>0, and Vdc is the terminal voltage on the low-voltage side of the output capacitor C1. A negative value is introduced into the regulation circuit to output a negative regulation signal.

[0048] In one embodiment of the present invention, Figure 4 and Figure 5 ,exist Figure 5 In the figure, the upper horizontal dotted line is the first loop compensation signal COMP1, the lower horizontal dotted line is the current threshold CSmin, and the first reference signal Vref varies between the first loop compensation signal COMP1 and the current threshold CSmin. When the first reference signal Vref is greater than the current threshold CSmin, the compensation capacitor in the control regulation circuit is charged, and the second loop compensation signal COMP2 increases, thereby reducing the first reference signal Vref. When the first reference signal Vref is less than the current threshold CSmin, the compensation capacitor in the control regulation circuit is discharged, and the second loop compensation signal COMP2 decreases, thereby increasing the first reference signal Vref. Figure 5 As shown, at time t1, the first reference signal Vref is less than the current threshold CSmin, and the compensation capacitor in the adjustment circuit is discharged. After discharging, the adjustment circuit controls the first reference signal Vref to increase. At time t2, the first reference signal Vref is greater than the current threshold CSmin, and the compensation capacitor in the adjustment circuit stops discharging and is charged again. In a specific embodiment of the present invention, the discharge speed of the compensation capacitor in the adjustment circuit is greater than the charging speed. By setting an appropriate current threshold CSmin, the power factor PF value of the LED drive system can be guaranteed, and the over-compensation and current threshold CSmin clamping caused by different application scenarios can be avoided. Through the adjustment control of the adjustment circuit, the minimum value of the first reference signal Vref is finally stabilized near the current threshold CSmin, which can effectively improve the compensation effect. On the premise of ensuring the stable operation of the circuit system, the power consumption of the LED drive control circuit is reduced, and the system efficiency is improved.

[0049] An embodiment of the present invention further discloses an LED driving system, the LED driving system comprising the LED driving control circuit as described in any one of the above items. Figure 3In one embodiment shown, the LED drive system includes a rectifier circuit, an LED load, and an LED drive control circuit. The LED drive control circuit includes a charging control circuit and an LED current control circuit. The charging control circuit includes a voltage detection circuit 11, a first loop compensation circuit 12, a reference signal generation circuit 13, a regulation circuit 15, and a first operational amplifier circuit 14. The charging control circuit is used to control the charging current of the output capacitor C1. In one embodiment of the present invention, as shown in FIG. Figure 3 As shown, the LED current control circuit includes a second operational amplifier circuit 15, which is used to control the current flowing through the LED load. A first input terminal of the second operational amplifier circuit 15 receives a reference signal. A second input terminal of the second operational amplifier circuit 15 is coupled to a second sampling resistor Rcs2 to obtain a current representative of the current flowing through the LED load. The output terminal of the second operational amplifier circuit 15 is coupled to a second transistor Q2. The current flowing through the LED load can be controlled by controlling the conduction level of the second transistor Q2, thereby achieving a constant current output of the LED load.

[0050] An embodiment of the present invention further discloses an LED drive control method, which is used to control the charging current of the output capacitor in the LED drive system. The LED drive control method includes receiving a first detection signal representing the terminal voltage of the load, and generating a first loop compensation signal based on the first detection signal. In a specific embodiment, the first detection signal is as follows: Figure 3 The first loop compensation circuit generates a first loop compensation signal COMP1 based on the first detection signal Vdl. The LED drive control circuit can control the first detection signal Vdl through the generated first loop compensation signal COMP1, that is, the LED drive control circuit can control the terminal voltage of the load. The LED drive control method also includes generating a first reference signal based on the first loop compensation signal; generating an adjustment signal based on the current threshold and the first reference signal to adjust the first reference signal. In a specific embodiment, when the adjustment signal plays a regulating role, the first reference signal is generated based on the first loop compensation signal and the adjustment signal; when the adjustment signal does not play a regulating role, the first reference signal is generated based on the first loop compensation signal. The LED drive control method also includes controlling the first transistor to control the charging current of the output capacitor based on the first reference signal and a first current sampling signal representing the charging current of the output capacitor.

[0051] In another embodiment of the present invention, the LED drive control method further includes: receiving a first detection signal or a terminal voltage at one end of the output capacitor as a second detection signal; generating a second loop compensation signal based on the first reference signal and the current threshold; and generating an adjustment signal based on the second detection signal and the second loop compensation signal.

[0052] In yet another embodiment of the present application, the adjustment circuit adjusts the second loop compensation signal to decrease the first reference signal when the first reference signal is greater than the current threshold, and adjusts the second loop compensation signal to increase the first reference signal when the first reference signal is less than the current threshold.

[0053] Those skilled in the art should know that "high level" and "low level", "set" and "reset", "and gate" and "or gate", "in-phase input end" and "inverted input end" and other logic controls in the logical controls involved in the description or the drawings can be interchanged or changed, and the same functions or purposes as the above embodiments can be achieved by adjusting the subsequent logic controls.

[0054] The description and application of the present application herein are illustrative, and are not intended to limit the scope of the present application to the above embodiments. The effects or advantages related descriptions involved in the description can not be embodied in actual experimental examples due to the uncertainty of specific conditions parameters or other factors, and the effects or advantages related descriptions are not used to limit the scope of the application. Variations and changes of the disclosed embodiments are possible, and the alternatives and equivalent components of the embodiments are known to those skilled in the art. It should be clear to those skilled in the art that the present application can be realized in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential characteristics of the present application. Other variations and changes of the disclosed embodiments can be made without departing from the scope and spirit of the present application.

Claims

1. An LED drive control circuit, characterized by, The LED driving control circuit comprises: a first loop compensation circuit, an input terminal of which receives a first detection signal representing a terminal voltage of a load, for generating a first loop compensation signal according to the first detection signal; a reference signal generation circuit, a first input terminal of which is coupled to the first loop compensation circuit, for generating a first reference signal according to the first loop compensation signal; an adjustment circuit, a first input terminal of which receives a current threshold value, a second input terminal of which is coupled to an output terminal of the reference signal generation circuit, for generating an adjustment signal according to the current threshold value and the first reference signal to adjust the first reference signal; and a first operational amplifier circuit, a first input terminal of which is coupled to the reference signal generation circuit, a second input terminal of which receives a first current sampling signal representing a charging current of an output capacitor, and an output terminal of which is coupled to the first transistor.

2. The LED drive control circuit of claim 1, wherein, The adjustment circuit comprises: a voltage acquisition circuit, an input terminal of which receives the first detection signal or a terminal voltage of one end of the output capacitor as a second detection signal; a second loop compensation circuit, a first input terminal of which receives the first reference signal, and a second input terminal of which receives the current threshold value, for generating a second loop compensation signal according to the first reference signal and the current threshold value; and an adjustment signal generation circuit, input terminals of which are coupled to the voltage acquisition circuit and the second loop compensation circuit respectively, for generating the adjustment signal according to the second detection signal and the second loop compensation signal.

3. The LED drive control circuit of claim 2, wherein, When the first reference signal is greater than the current threshold value, the adjustment circuit adjusts the second loop compensation signal to reduce the first reference signal; When the first reference signal is less than the current threshold value, the adjustment circuit adjusts the second loop compensation signal to increase the first reference signal.

4. The LED drive control circuit of claim 2, wherein, The adjustment circuit further comprises: a multiplier, a first input terminal of which is coupled to the voltage acquisition circuit, a second input terminal of which is coupled to the second loop compensation circuit, and an output terminal of which is coupled to the adjustment signal generation circuit.

5. The LED drive control circuit of claim 1, wherein, The reference signal generation circuit comprises: an operational circuit, a first input terminal of which is coupled to an output terminal of the first loop compensation circuit, a second input terminal of which is coupled to an output terminal of the adjustment circuit, and an output terminal of which is coupled to a first input terminal of the first operational amplifier circuit.

6. The LED drive control circuit of claim 1, wherein, The current threshold value is a preset fixed value, or the current threshold value is 1 / k1 times of the first loop compensation signal, where k1>1.

7. The LED drive control circuit of claim 3, wherein, When the first reference signal is greater than the current threshold value, a compensation capacitor in the adjustment circuit is charged; and when the first reference signal is less than the current threshold value, the compensation capacitor in the adjustment circuit is discharged, where a discharging speed is greater than a charging speed.

8. An LED driving system, characterized by, The LED driving system comprises the LED driving control circuit according to any one of claims 1-7.

9. A method for controlling an LED drive system, for controlling a charging current of an output capacitor in an LED drive system, characterized in that: The LED driving control method comprises: receiving a first detection signal representing a terminal voltage of a load, and generating a first loop compensation signal according to the first detection signal; generating a first reference signal according to the first loop compensation signal; generating an adjustment signal according to a current threshold value and the first reference signal to adjust the first reference signal; and controlling a first transistor to control a charging current of an output capacitor according to the first reference signal and a first current sampling signal representing the charging current of the output capacitor.

10. The LED driving control method according to claim 9, wherein The LED driving control method further comprises: receiving the first detection signal or a terminal voltage of one end of the output capacitor as a second detection signal; generating a second loop compensation signal from the first reference signal and a current threshold; and generating an adjustment signal from the second detection signal and the second loop compensation signal.

11. The LED driving control method according to claim 10, wherein adjusting the second loop compensation signal to decrease the first reference signal when the first reference signal is greater than the current threshold; adjusting the second loop compensation signal to increase the first reference signal when the first reference signal is less than the current threshold.

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