Driving control circuit, LED driving control system and method

Abstract

The invention provides a driving control circuit and an LED driving control system and method, and the circuit comprises a hysteresis voltage generation module which is used for generating a hysteresis voltage upper limit and a hysteresis voltage lower limit, the hysteresis voltage upper limit changes periodically with a first preset voltage as an average value, and the hysteresis voltage lower limit changes periodically with a second preset voltage as an average value; the lower limit of the hysteresis voltage is second preset voltage or periodically changes by taking the second preset voltage as an average value; the hysteresis voltage upper limit and the hysteresis voltage lower limit have the same variable quantity and opposite change directions; and the control module generates a driving control signal based on a comparison result of the sampling voltage and the upper and lower limits of the hysteresis voltage. According to the invention, the hysteresis voltage upper limit is configured to change periodically to drive the switching frequency to change periodically, the energy at each switching frequency point is reduced, and the conducted interference emission of the driving control circuit is reduced; furthermore, the lower limit of the hysteresis voltage is configured to be periodically changed, so that the periodic fluctuation of the output current is avoided, and the requirement on stroboflash is met.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit design, and in particular to a drive control circuit, an LED drive control system and a method. Background Art

[0002] According to the light-emitting principle and characteristics of LED, constant current source is selected to drive LED lamp beads. Constant current source is usually divided into linear constant current source and switch mode constant current source. Switch mode constant current source stands out for its high efficiency and small size. Among them, Buck topology is widely used in medium and high power LED driving occasions because of its simple structure and strong versatility. Switch mode constant current source is usually divided into open-loop control and closed-loop control. Closed-loop control is widely used for its high steady-state accuracy and strong anti-disturbance ability. Among them, hysteresis current mode control has a broad market space in low-cost application fields because of its high loop bandwidth and no need for compensation network.

[0003] However, compared with the linear mode constant current source, the switch mode constant current source has the problem of large conducted interference. In order to meet the corresponding regulatory requirements, customers need to use a larger EMI filter, which leads to a larger size and higher cost. The loss of the filter itself reduces the product efficiency, which is not conducive to the fierce market competition.

[0004] Therefore, how to reduce the conducted interference emission of the LED driver while reducing the volume and cost and improving the efficiency has become one of the problems that those skilled in the art need to solve urgently.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a drive control circuit, an LED drive control system and a method for solving the problems of large size, high cost and low efficiency of LED drivers for reducing conducted interference in the prior art.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a drive control circuit, which at least includes:

[0008] Hysteresis voltage generating module and control module;

[0009] The hysteresis voltage generation module is used to generate an upper hysteresis voltage limit and a lower hysteresis voltage limit; wherein, the upper hysteresis voltage limit periodically varies with a first preset voltage as the average value, and the lower hysteresis voltage limit is a second preset voltage or periodically varies with the second preset voltage as the average value; when both the upper hysteresis voltage limit and the lower hysteresis voltage limit periodically vary, the variation amounts of the upper hysteresis voltage limit and the lower hysteresis voltage limit are the same and the variation directions are opposite.

[0010] The control module is connected to the output end of the hysteresis voltage generation module, receives the sampled voltage of the output current, and generates a drive control signal based on the comparison result between the sampled voltage and the upper and lower hysteresis voltage limits.

[0011] Optionally, the hysteresis voltage generation module includes a preset voltage generation unit, a waveform generator and an adder;

[0012] The preset voltage generation unit is used to generate the constant first preset voltage and the second preset voltage;

[0013] The waveform generator is used to generate an alternating voltage;

[0014] The first input end of the adder is connected to the output end of the preset voltage generation unit, and the second input end is connected to the output end of the waveform generator, and is used to superimpose the alternating voltage on the first preset voltage to obtain the upper hysteresis voltage limit.

[0015] More optionally, when both the upper hysteresis voltage limit and the lower hysteresis voltage limit periodically vary, the hysteresis voltage generation module further includes a subtractor;

[0016] The first input end of the subtractor is connected to the output end of the preset voltage generation unit, and the second input end is connected to the output end of the waveform generator, and is used to inversely superimpose the alternating voltage on the second preset voltage to obtain the lower hysteresis voltage limit.

[0017] More optionally, the alternating voltage is a sine wave, a square wave or a triangular wave.

[0018] To achieve the above and other related purposes, the present invention further provides an LED drive control system, which at least includes:

[0019] A switching current source circuit, an LED load and the above drive control circuit;

[0020] The drive control circuit is used to provide a drive control signal;

[0021] The switching current source circuit receives the drive control signal and adjusts the output current based on the drive control signal;

[0022] The LED load is connected to the switched current source circuit and emits light based on the output current of the switched current source circuit.

[0023] Optionally, the switched current source circuit is of a BUCK topology.

[0024] More optionally, the switched current source circuit includes an input capacitor, a diode, an inductor, an output capacitor, a sampling resistor, and a power switch;

[0025] The upper plate of the input capacitor is connected to the bus voltage, and the lower plate is grounded;

[0026] The cathode of the diode is connected to the upper plate of the input capacitor, and the anode is grounded via the power switch;

[0027] One end of the sampling resistor is connected to the upper plate of the input capacitor, and the other end is connected to the anode of the diode via the output capacitor and the inductor in sequence.

[0028] To achieve the above and other related objectives, the present invention also provides an LED driving control method, which at least includes:

[0029] Generating an upper hysteresis voltage limit and a lower hysteresis voltage limit, and collecting the current flowing through the LED; wherein, the upper hysteresis voltage limit periodically varies with a first preset voltage as the average value, the lower hysteresis voltage limit is a second preset voltage or periodically varies with a second preset voltage as the average value; when both the upper hysteresis voltage limit and the lower hysteresis voltage limit periodically vary, the variation amounts of the upper hysteresis voltage limit and the lower hysteresis voltage limit are the same and the variation directions are opposite;

[0030] When the sampling voltage of the current flowing through the LED rises to the upper hysteresis voltage limit, the power switch for regulating the LED current is turned off; when the sampling voltage of the current flowing through the LED drops to the lower hysteresis voltage limit, the power switch is turned on.

[0031] Optionally, an AC voltage is superimposed on the constant first preset voltage to obtain the upper hysteresis voltage limit.

[0032] Optionally, when both the upper hysteresis voltage limit and the lower hysteresis voltage limit periodically vary, an AC voltage is superimposed on the constant second preset voltage to obtain the lower hysteresis voltage limit.

[0033] As described above, the driving control circuit, the LED driving control system, and the method of the present invention have the following beneficial effects:

[0034] The drive control circuit, LED drive control system and method of the present invention configure the upper limit of the hysteresis voltage to change periodically, so as to drive the switching frequency to change periodically, and evenly distribute the energy originally mainly distributed at the fixed switching frequency points to several switching frequency points, thereby greatly reducing the energy at each switching frequency point and reducing the conducted interference emission of the drive control circuit. Further, the drive control circuit, LED drive control system and method of the present invention also configure the lower limit of the hysteresis voltage to change periodically. By the anti-phase periodic change of the upper limit of the hysteresis voltage and the lower limit of the hysteresis voltage, the periodic fluctuation of the output current is avoided, and the requirement for stroboscopic is met while reducing the conducted interference. Description of the Drawings

[0035] Figure 1 It shows a schematic diagram of the working principle and the waveform of the switching node of a constant current control method in a hysteresis current mode.

[0036] Figure 2 It shows a schematic diagram of the structure of the drive control circuit of the present invention.

[0037] Figure 3 It shows a schematic diagram of a structure of the hysteresis voltage generation module of the present invention.

[0038] Figure 4 It shows a schematic diagram of the working principle and the waveform of the switching node of a kind of LED drive control method of the present invention.

[0039] Figure 5 It shows a schematic diagram of another structure of the hysteresis voltage generation module of the present invention.

[0040] Figure 6 It shows a schematic diagram of the working principle and the waveform of the switching node of another kind of LED drive control method of the present invention.

[0041] Figure 7 It shows a schematic diagram of the structure of the LED drive control system of the present invention.

[0042] Description of Component Labels

[0043] 1 Drive control circuit

[0044] 11 Hysteresis voltage generation module

[0045] 111 Preset voltage generation unit

[0046] 112 Waveform generator

[0047] 113 Adder

[0048] 114 Subtractor

[0049] 12 Control module

[0050] 2 Switch current source circuit Specific embodiments

[0051] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0052] Please refer to Figures 1 to 7 . It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0053] A hysteretic current mode constant current control method converts the inductor current into a proportional voltage signal Vcs through a current sensing resistor, and sets a hysteresis voltage upper limit VH and a hysteresis voltage lower limit VL. As Figure 1 shown, when the voltage signal Vcs rises to reach the hysteresis voltage upper limit VH, the power switch is turned off, and the voltage signal Vcs gradually decreases; when the voltage signal Vcs drops to reach the hysteresis voltage lower limit VL, the power switch is turned on, and the voltage signal Vcs gradually rises; this cycle repeats, and the average value Vavg of the voltage signal Vcs is controlled to be (VH + VL) / 2. Then, the inductor current is also proportionally controlled. When the power switch is turned on, the voltage Vsw at the connection node between the power switch and the inductor is at a low level; when the power switch is turned off, the voltage Vsw at the connection node between the power switch and the inductor is at a high level.

[0054] From Figure 1 the waveform of the voltage Vsw at the connection node between the power switch and the inductor in, it can be seen that in practical applications, due to the input voltage, output voltage, inductance, and the upper and lower limits of the hysteresis voltage remaining constant, the switching frequency of the power switch remains constant. By performing Fourier series decomposition on the voltage Vsw at the connection node between the power switch and the inductor, it can be known that at the switching frequency point and the frequency points that are multiples of the switching frequency, the energy of high-frequency interference is relatively large. In order to meet the relevant regulatory requirements, it is necessary to add an EMI filter at the input and output ports of the LED driver to attenuate this high-frequency interference, and the added EMI filter makes the volume of the product larger, the cost higher, and the efficiency lower.

[0055] Based on the above problems, the present invention provides a hysteretic current mode drive control circuit with a frequency jitter function, an LED drive control system and method, which can reduce the conducted interference of the LED driver while eliminating the EMI filter or reducing the volume of the EMI filter, thereby reducing the cost of the product and enhancing the competitiveness of the product.

[0056] Embodiment 1

[0057] As Figure 2 shown, this embodiment provides a drive control circuit 1, and the drive control circuit 1 includes:

[0058] A hysteretic voltage generation module 11 and a control module 12.

[0059] As Figure 2 shown, the hysteretic voltage generation module 11 is used to generate a hysteretic voltage upper limit VH and a hysteretic voltage lower limit VL. Among them, the hysteretic voltage upper limit VH periodically varies with a first preset voltage Vset1 as the average value, the hysteretic voltage lower limit VL is a second preset voltage Vset2, and the hysteretic voltage upper limit VH is greater than the hysteretic voltage lower limit VL.

[0060] Specifically, as Figure 3 shown, in this embodiment, the hysteretic voltage generation module 11 includes a preset voltage generation unit 111, a waveform generator 112 and an adder 113.

[0061] More specifically, the preset voltage generation unit 111 is used to generate the first preset voltage Vset1 and the second preset voltage Vset2; as an example, both the first preset voltage Vset1 and the second preset voltage Vset2 are constant values, the first preset voltage Vset1 is greater than the second preset voltage Vset2, and any circuit structure capable of generating two preset voltages is applicable to the present invention and will not be elaborated here one by one. It should be noted that in actual use, the first preset voltage Vset1 and / or the second preset voltage Vset2 can also be configured as variable values (such as linearly increasing or linearly decreasing) according to needs, not limited to this embodiment.

[0062] More specifically, the waveform generator 112 is used to generate an alternating voltage, the average value of the alternating voltage is zero (that is, the area above the X-axis is equal to the area below the X-axis), and the waveform of the alternating voltage is not limited, including but not limited to sine wave, square wave or triangular wave, which will not be listed one by one here. In this embodiment, the alternating voltage is a sine wave.

[0063] More specifically, the first input terminal of the adder 113 is connected to the output terminal of the preset voltage generating unit 111, and the second input terminal is connected to the output terminal of the waveform generator 112, which is used to superimpose the AC voltage on the first preset voltage Vset1 to obtain the upper limit VH of the hysteresis voltage.

[0064] As Figure 3 and Figure 4 shown, the second preset voltage Vset2 in the preset voltage generating unit 111 is output as the lower limit VL of the hysteresis voltage, and the lower limit VL of the hysteresis voltage is a constant value. The adder 113 outputs the upper limit VH of the hysteresis voltage, and the upper limit VH of the hysteresis voltage changes periodically with the first preset voltage Vset1 as the average value and has a sinusoidal waveform.

[0065] As Figure 2 shown, the control module 12 is connected to the output terminal of the hysteresis voltage generating module 11 and receives the sampled voltage Vcs of the output current, and generates a drive control signal Drv based on the comparison result between the sampled voltage Vcs and the upper and lower limits (VH, VL) of the hysteresis voltage.

[0066] Specifically, as Figure 4 shown, the control module 12 is used to implement the drive control of the hysteresis current mode. When the sampled voltage Vcs rises to the upper limit VH of the hysteresis voltage, a drive control signal Drv that decreases the sampled voltage Vcs is generated; when the sampled voltage Vcs drops to the lower limit VL of the hysteresis voltage, a drive control signal Drv that increases the sampled voltage Vcs is generated; so as to limit the average value Vavg of the sampled voltage Vcs to (VH + VL) / 2. The average value Vavg of the sampled voltage Vcs has a sinusoidal waveform, and the fluctuation amplitude is slightly smaller than the upper limit VH of the hysteresis voltage.

[0067] The drive control circuit 1 of the present invention drives the switching frequency to change periodically through the periodic change of the upper limit of the hysteresis voltage, and distributes the energy originally mainly distributed at the fixed switching frequency points evenly among several switching frequency points. The energy at each switching frequency point will be greatly reduced, thereby reducing the conducted interference emission of the drive control circuit. Users can easily meet the regulatory requirements without using an EMI filter or by reducing the size of the EMI filter, making the product have market competitiveness.

[0068] Embodiment 2

[0069] The disadvantage of the drive control circuit 1 in the first embodiment is that the periodic change (jitter) of the upper limit of the hysteresis voltage is transmitted to the output current, resulting in periodic fluctuations in the average output current, which limits the application scenarios with requirements for stroboscopic. In response to this, this embodiment provides a drive control circuit 1, wherein the lower limit VL of the hysteresis voltage is configured to periodically change with the second preset voltage as the average value.

[0070] Specifically, the lower limit VL of the hysteresis voltage periodically changes with the second preset voltage Vset2 as the average value, and the change amount of the upper limit VH of the hysteresis voltage is the same as that of the lower limit VL of the hysteresis voltage, and the change directions are opposite (that is, when the upper limit VH of the hysteresis voltage increases, the lower limit VL of the hysteresis voltage decreases, and when the upper limit VH of the hysteresis voltage decreases, the lower limit VL of the hysteresis voltage increases). As an example, on the basis of the hysteresis voltage generation module 11 in the first embodiment, the hysteresis voltage generation module 11 further includes a subtractor 114; as Figure 5 shown, the first input end of the subtractor 114 is connected to the output end of the preset voltage generation unit 111, and the second input end is connected to the output end of the waveform generator 112, and is used to invert and superimpose the AC voltage on the second preset voltage Vset2 to obtain the lower limit VL of the hysteresis voltage.

[0071] As Figure 5 and Figure 6 shown, the adder 113 outputs the upper limit VH of the hysteresis voltage, the upper limit VH of the hysteresis voltage periodically changes with the first preset voltage Vset1 as the average value, and is in a sine wave form. The subtractor 114 outputs the lower limit VL of the hysteresis voltage, the lower limit VL of the hysteresis voltage periodically changes with the second preset voltage Vset2 as the average value, and is in a sine wave form.

[0072] As Figure 6 shown, the control module 12 is used to implement the drive control in the hysteresis current mode. For the specific working principle, refer to the above, and details are not described here one by one. The average value Vavg of the sampling voltage Vcs is limited to (VH + VL) / 2. Since the upper limit VH of the hysteresis voltage and the lower limit VL of the hysteresis voltage periodically change in opposite directions, the average value Vavg of the sampling voltage Vcs is a constant value. The purpose of evenly distributing the energy at several switching frequency points can also be achieved. At the same time, there is no periodic fluctuation in the output current, and the stability is higher, which is suitable for application scenarios with requirements for stroboscopic.

[0073] Embodiment Three

[0074] As Figure 7 shown, this embodiment provides an LED drive control system, and the LED drive control system includes:

[0075] The drive control circuit 1, the switched current source circuit 2, and the LED load.

[0076] As Figure 7 shown, the drive control circuit 1 is used to provide a drive control signal Drv.

[0077] Specifically, the drive control circuit 1 is implemented by using the drive control circuit of Embodiment 1 or Embodiment 2. For the specific structure and principle, refer to Embodiment 1 or Embodiment 2, and details are not described herein one by one.

[0078] As Figure 7 shown, the switched current source circuit 2 receives the drive control signal Drv and adjusts the output current based on the drive control signal Drv.

[0079] Specifically, any switched power supply structure is applicable to the present invention, including but not limited to the BUCK topology, the BOOST topology, the BUCK - BOOST topology, and their modified structures, and details are not described herein one by one. As an example, the switched current source circuit 2 includes an input capacitor Cin, a diode D, an inductor L, an output capacitor Cout, a sampling resistor Rcs, and a power switch Q. The upper plate of the input capacitor Cin is connected to the bus voltage, and the lower plate is grounded; the cathode of the diode D is connected to the upper plate of the input capacitor Cin, and the anode is grounded via the power switch Q; one end of the sampling resistor Rcs is connected to the upper plate of the input capacitor Cin, and the other end is connected to the anode of the diode D via the output capacitor Cout and the inductor L in sequence; in this example, the power switch Q is an NMOS transistor. The drive control circuit 1 is connected to both ends of the sampling resistor Rcs to obtain the sampling voltage Vcs.

[0080] It should be noted that in actual use, the sampling resistor Rcs can also be connected in series between the inductor L and the anode of the diode D; or in series between the connection node of the diode D and the inductor L and the drain of the power switch Q. The sampling resistor Rcs can be set at any position that can directly or indirectly detect the current on the inductor L, and is not limited to this embodiment.

[0081] As Figure 7 shown, the LED load is connected to the switched current source circuit 2 and emits light based on the output current of the switched current source circuit 2.

[0082] Specifically, in this embodiment, the positive electrode of the LED load is connected to the upper plate of the output capacitor Cout, and the negative electrode is connected to the lower plate of the output capacitor Cout.

[0083] Embodiment 4

[0084] This embodiment provides an LED driving control method, and the LED driving control method includes:

[0085] Generate a hysteresis voltage upper limit VH and a hysteresis voltage lower limit VL, and collect the current flowing through the LED; wherein, the hysteresis voltage upper limit VH periodically varies with a first preset voltage Vset1 as the average value, and the hysteresis voltage lower limit VL is a second preset voltage Vset2 or periodically varies with the second preset voltage Vset2 as the average value; when both the hysteresis voltage upper limit VH and the hysteresis voltage lower limit VL periodically vary, the change amounts of the hysteresis voltage upper limit VH and the hysteresis voltage lower limit VL are the same and the change directions are opposite;

[0086] When the sampling voltage Vcs of the current flowing through the LED rises to the hysteresis voltage upper limit VH, turn off the power switch tube Q that regulates the LED current; when the sampling voltage Vcs of the current flowing through the LED drops to the hysteresis voltage lower limit VL, turn on the power switch tube Q.

[0087] Specifically, in this embodiment, the LED driving control method is implemented based on the LED driving control system of Embodiment 3. In actual use, any hardware or software that can implement this method is applicable and is not limited to this embodiment.

[0088] As Figure 7 and Figure 4 shown, for the solution where the hysteresis voltage upper limit VH periodically varies and the hysteresis voltage lower limit VL is a constant value, in this embodiment, an alternating voltage is superimposed on the constant first preset voltage Vset1 to obtain the periodically varying hysteresis voltage upper limit VH. Wherein, the average value of the alternating voltage is zero, and the waveform of the alternating voltage is not limited, including but not limited to sine wave, square wave or triangular wave, which are not listed one by one here; in this embodiment, the alternating voltage is a sine wave.

[0089] As Figure 7 and Figure 6 shown, for the solution where both the hysteresis voltage upper limit VH and the hysteresis voltage lower limit VL periodically vary, in this embodiment, an alternating voltage is superimposed on the constant second preset voltage Vset2 to obtain the periodically varying hysteresis voltage lower limit VH.

[0090] As Figure 2 , Figure 4 , Figures 6 to 7As shown, the control module 12 acquires the sampled voltage Vcs and compares the sampled voltage Vcs with the upper hysteresis voltage VH and the lower hysteresis voltage VL; when the sampled voltage Vcs rises to the upper hysteresis voltage VH, the drive control signal Drv jumps to a low level, the power switch Q turns off, the voltage Vsw at the connection node of the power switch Q and the inductor L is at a high level, and the sampled voltage Vcs gradually decreases; when the sampled voltage Vcs drops to the lower hysteresis voltage VL, the drive control signal Drv jumps to a high level, the power switch Q turns on, the voltage Vsw at the connection node of the power switch Q and the inductor L is at a low level, and the sampled voltage Vcs gradually increases. Repeating this cycle, the average value Vavg of the sampled voltage Vcs is limited to (VH + VL) / 2, and the output current is controlled accordingly.

[0091] Due to the periodic change of the upper hysteresis voltage VH, or the periodic changes of the upper hysteresis voltage VH and the lower hysteresis voltage VL, the switching frequency of the power switch Q also changes periodically, and the switching frequency can be changed periodically, thereby dispersing the energy at specific switching frequency points; moreover, there is no fluctuation in the output current during the periodic changes of the upper hysteresis voltage VH and the lower hysteresis voltage VL.

[0092] In summary, the present invention provides a drive control circuit, an LED drive control system and a method, including: a hysteresis voltage generation module and a control module; the hysteresis voltage generation module is used to generate a hysteresis voltage upper limit and a hysteresis voltage lower limit; wherein, the hysteresis voltage upper limit periodically changes with a first preset voltage as an average value, and the hysteresis voltage lower limit is a second preset voltage or periodically changes with the second preset voltage as an average value; when both the hysteresis voltage upper limit and the hysteresis voltage lower limit periodically change, the change amounts of the hysteresis voltage upper limit and the hysteresis voltage lower limit are the same and the change directions are opposite; the control module is connected to the output end of the hysteresis voltage generation module, receives the sampling voltage of the output current, and generates a drive control signal based on the comparison results of the sampling voltage with the hysteresis voltage upper and lower limits. In the drive control circuit, the LED drive control system and the method of the present invention, the hysteresis voltage upper limit is configured to periodically change to drive the switching frequency to periodically change, and the energy originally mainly distributed at the fixed switching frequency points is evenly distributed at several switching frequency points, thereby greatly reducing the energy at each switching frequency point and reducing the conducted interference emission of the drive control circuit; further, in the drive control circuit, the LED drive control system and the method of the present invention, the hysteresis voltage lower limit is also configured to periodically change, and through the anti-phase periodic change of the hysteresis voltage upper limit and the hysteresis voltage lower limit, the periodic fluctuation of the output current is avoided, and the requirement for stroboscopic is satisfied while reducing the conducted interference. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0093] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A drive control circuit, characterized in that, The driving control circuit at least includes: a hysteresis voltage generation module and a control module; The hysteresis voltage generation module is used to generate a hysteresis voltage upper limit and a hysteresis voltage lower limit; wherein, the hysteresis voltage upper limit periodically varies with the first preset voltage as the average value, and the hysteresis voltage lower limit is the second preset voltage or periodically varies with the second preset voltage as the average value; when both the hysteresis voltage upper limit and the hysteresis voltage lower limit periodically vary, the variation amounts of the hysteresis voltage upper limit and the hysteresis voltage lower limit are the same and the variation directions are opposite; The control module is connected to the output end of the hysteresis voltage generation module, receives the sampling voltage of the output current, and generates a driving control signal based on the comparison results of the sampling voltage with the hysteresis voltage upper and lower limits.

2. The drive control circuit according to claim 1, wherein: The hysteresis voltage generation module includes a preset voltage generation unit, a waveform generator, and an adder; The preset voltage generation unit is used to generate the constant first preset voltage and the second preset voltage; The waveform generator is used to generate an alternating voltage; The first input end of the adder is connected to the output end of the preset voltage generation unit, and the second input end is connected to the output end of the waveform generator, and is used to superimpose the alternating voltage on the first preset voltage to obtain the hysteresis voltage upper limit.

3. The drive control circuit according to claim 2, wherein: When both the hysteresis voltage upper limit and the hysteresis voltage lower limit periodically vary, the hysteresis voltage generation module further includes a subtractor; The first input end of the subtractor is connected to the output end of the preset voltage generation unit, and the second input end is connected to the output end of the waveform generator, and is used to inversely superimpose the alternating voltage on the second preset voltage to obtain the hysteresis voltage lower limit.

4. The drive control circuit according to claim 2 or 3, characterized in that: The alternating voltage is a sine wave, a square wave or a triangular wave.

5. An LED driving control system, characterized in that, The LED driving control system at least includes: a switching current source circuit, an LED load, and the driving control circuit according to any one of claims 1-4; The driving control circuit is used to provide a driving control signal; The switching current source circuit receives the driving control signal and adjusts the output current based on the driving control signal; The LED load is connected to the switching current source circuit and emits light based on the output current of the switching current source circuit.

6. The LED driving control system according to claim 5, wherein: The switching current source circuit is of a BUCK topology structure.

7. The LED driving control system according to claim 6, wherein: The switching current source circuit includes an input capacitor, a diode, an inductor, an output capacitor, a sampling resistor, and a power switch tube; The upper plate of the input capacitor is connected to the bus voltage, and the lower plate is grounded; The cathode of the diode is connected to the upper plate of the input capacitor, and the anode is grounded via the power switch tube; One end of the sampling resistor is connected to the upper plate of the input capacitor, and the other end is sequentially connected to the anode of the diode via the output capacitor and the inductor.

8. An LED driving control method, characterized in that, The LED driving control method at least includes: Generate the upper limit and lower limit of the hysteresis voltage, and collect the current flowing through the LED; wherein, the upper limit of the hysteresis voltage changes periodically with the first preset voltage as the average value, and the lower limit of the hysteresis voltage is the second preset voltage or changes periodically with the second preset voltage as the average value; when both the upper limit and the lower limit of the hysteresis voltage change periodically, the change amounts of the upper limit and the lower limit of the hysteresis voltage are the same and the change directions are opposite. When the sampling voltage of the current flowing through the LED rises to the upper limit of the hysteresis voltage, turn off the power switch tube for regulating the LED current; when the sampling voltage of the current flowing through the LED drops to the lower limit of the hysteresis voltage, turn on the power switch tube.

9. The LED driving control method according to claim 8, characterized in that: Superimpose an AC voltage on the constant first preset voltage to obtain the upper limit of the hysteresis voltage.

10. The LED driving control method according to claim 8, wherein: When both the upper limit and the lower limit of the hysteresis voltage change periodically, superimpose an AC voltage on the constant second preset voltage to obtain the lower limit of the hysteresis voltage.

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