LED dual-loop control circuit and control method

Abstract

The present disclosure provides an LED dual-loop control circuit and a control method. The present disclosure adds a fast response module to a traditional loop-integrated controlled LED circuit. The fast response module is connected to the loop-integrated control module and a sampling resistor respectively. The fast response module has a larger bandwidth than the loop-integrated control module. Based on the acquisition of sampling parameters of the sampling resistor, the fast response module can realize fast on-off control of a power tube based on the sampling parameters and a first reference value, thereby playing an overall protective role for the LED circuit and improving the reliability of the circuit.

Description

Technical Field

[0001] The present disclosure relates to the field of linear LED (Light Emitting Diode) driving, and in particular to an LED dual-loop control circuit and a control method. Background Art

[0002] LED light source is a light source based on light-emitting diodes. It has the advantages of using low-voltage power supply, low energy consumption, strong applicability, high stability, short response time, no pollution to the environment, and multi-color light emission, and is widely used. The LED driver using loop integral control has the advantages of good constant current effect, high output current accuracy, good linear adjustment rate and load adjustment rate, and is widely used. However, the LED driver with loop integral control also has obvious disadvantages. It is not sensitive to the instantaneous current of the output and only guarantees the stability of the average value of the output current. The response speed of the loop integral is slow. In an environment that exceeds the circuit carrying capacity, it is easy to have a long-term high current, causing circuit damage and affecting use. Summary of the invention

[0003] The purpose of the embodiments of the present disclosure is to provide an LED dual-loop control circuit and a control method to solve the problem that the LED circuit with loop integral control in the prior art has slow transient response speed and is prone to failure.

[0004] In order to solve the above technical problems, the embodiment of the present disclosure adopts the following technical solutions: an LED dual-loop control circuit, comprising: a power supply module, a loop integration control module and an LED load, wherein the input end of the power supply module is connected to a bus, the input end of the loop integration control module is respectively connected to the output end of the power supply module and the first end of a sampling resistor, the first end of the LED load is connected to the bus, the second end of the LED load is connected to the first end of the sampling resistor through a power tube, and the second end of the sampling resistor is grounded, and further comprising: a fast response module, the input end of the fast response module is respectively connected to the output end of the loop integration control module and the first end of the sampling resistor, the output end of the fast response module is connected to the gate of the power tube, and the fast response module drives the power tube to be turned on and off based on the first reference value output by the loop integration control module and the sampling parameter of the sampling resistor.

[0005] Furthermore, it also includes: an undervoltage lockout module and a bandgap reference module; wherein the output end of the power supply module is connected to the undervoltage lockout module and the bandgap reference module respectively, the input end of the loop integral control module is connected to the output end of the undervoltage lockout module, the output end of the bandgap reference module and the first end of the sampling resistor respectively; the input end of the fast response module is also connected to the output end of the undervoltage lockout module.

[0006] Furthermore, the fast response module at least includes an operational amplifier, a first input end of the operational amplifier is connected to the output end of the loop control module, and is used to receive a first reference value output by the loop control module, a second input end of the operational amplifier is connected to the first end of the sampling resistor, and is used to receive a sampling parameter of the sampling resistor, and an output end of the operational amplifier is connected to the gate of the power tube; the operational amplifier controls the power tube based on a comparison result between the first reference value and the sampling parameter.

[0007] Further, the fast response module includes: an operational amplifier, a first input end of the operational amplifier is connected to the output end of the loop control module, and is used to receive a first reference value output by the loop control module; a second input end of the operational amplifier is connected to the first end of the sampling resistor, and is used to receive a sampling parameter of the sampling resistor; and an output end of the operational amplifier is connected to the gate of the power tube; a comparator, a first input end of the comparator is connected to the output end of the bandgap reference module, and is used to receive a second reference value output by the bandgap reference module; a second input end of the comparator is connected to the first end of the sampling resistor, and is used to receive the sampling parameter of the sampling resistor; and a timing unit, an input end of the timing unit is connected in series with an output end of the comparator, and an output end of the timing unit is connected to an input end of the loop integral control module.

[0008] Furthermore, the timing unit at least includes: a timer and an oscillation module; the input end of the timer is connected in series with the output end of the comparator, and the output end of the timer is connected to the input end of the loop integral control module; the oscillation module is connected in series with the timer to input a standard clock signal to the timer.

[0009] Further, when the sampling parameter input by the comparator is less than the second reference value, the comparator outputs an activation signal to the timing unit; the timing unit starts to count a first time length when receiving the activation signal, and when the first time length exceeds a preset time length, the timing unit outputs a reset signal to the loop integration control module; the loop integration control module adjusts the first reference value outputted from its output end to 0 based on the reset signal; and the operational amplifier controls the power tube based on the comparison result between the first reference value and the sampling parameter.

[0010] An embodiment of the present disclosure also provides an LED dual-loop control method, which is applied to the above-mentioned LED dual-loop control circuit, including: obtaining sampling parameters of a sampling resistor; controlling the on and off of a power tube based on a comparison result between the sampling parameters and a first reference value; wherein the first reference value is obtained through a loop integral control module.

[0011] Further, after obtaining the sampling parameter of the sampling resistor, it also includes: when the sampling parameter is less than a second reference value and the duration is greater than or equal to a preset time length, turning off the power tube; wherein the preset time length is greater than or equal to one cycle of the post-bridge bus voltage.

[0012] Further, the second reference value is obtained through a bandgap reference module.

[0013] The beneficial effects of the embodiments of the present disclosure are as follows: by adding a fast response module to the traditional loop-integrated controlled LED circuit, the fast response module is respectively connected to the loop-integrated control module and the sampling resistor, and has a larger bandwidth than the loop-integrated control module. Based on the acquisition of the sampling parameters of the sampling resistor, the fast response module can realize fast on-off control of the power tube based on the sampling parameters and the first reference value, thereby playing an overall protective role for the LED circuit and improving the reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a connection diagram of an LED control circuit in the prior art;

[0015] Figure 2 It is a connection diagram of a dual-loop control circuit in the first embodiment of the present disclosure;

[0016] Figure 3 is another connection schematic diagram of the dual-loop control circuit in the first embodiment of the present disclosure;

[0017] Figure 4 This is a connection diagram of a first preferred implementation of a dual-loop control circuit in the first embodiment of the present disclosure;

[0018] Figure 5 It is a connection diagram of a second preferred implementation of the dual-loop control circuit in the first embodiment of the present disclosure;

[0019] Figure 6 is a flow chart of a dual-loop control method in the second embodiment of the present disclosure;

[0020] Figure 7 This is another flow chart of the dual-loop control method in the second embodiment of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 10-Power module 20-Undervoltage lockout module 30-Bandgap reference module

[0023] 40- loop integral control module 50- LED load 52- capacitor

[0024] 60-Quick response module 70-Drive module DETAILED DESCRIPTION

[0025] Various aspects and features of the present application are described herein with reference to the accompanying drawings.

[0026] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but only as an example of an embodiment. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0028] These and other characteristics of the present application will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0029] It should also be understood that, although the present application has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present application that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0030] The above and other aspects, features and advantages of the present application will become more apparent in view of the following detailed description when taken in conjunction with the accompanying drawings.

[0031] Specific embodiments of the present application are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments applied for are merely examples of the present application, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that obscure the present application. Therefore, the specific structural and functional details applied for herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present application in a variety of ways with substantially any suitable detailed structure.

[0032] This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present application.

[0033] Figure 1 FIG. 1 shows a connection diagram of an LED control circuit in the prior art, which mainly includes: a power module 10, an under voltage lockout (UVLO) module 20, a bandgap reference module 30, a loop integral control module 40, an LED load 50 and a drive module 70. Figure 1As shown, the input end of the power module 10 is connected to the bus (mains), the output end of the power module 10 is connected to the undervoltage lockout module 20 and the bandgap reference module 30 respectively, and the input end of the loop integral control module 40 is connected to the output end of the undervoltage lockout module 20, the output end of the bandgap reference module 30 and the sampling resistor R cs The first end of the loop integral control module 40 is connected to the gate of the power tube Q1 through the driving module 70, the first end of the LED load 50 is connected to the bus (mains), and the second end of the LED load 50 is connected to the sampling resistor R through the power tube Q1. cs The first end of the sampling resistor R cs LED load 50 may be an LED lamp or an LED lamp group, and a filtering capacitor 52 may be connected in parallel at both ends of the load.

[0034] In passing Figure 1 When the circuit shown in the figure drives the LED, the power module 10 obtains energy (V M ) for the LED control circuit to work; the undervoltage lockout module 20 detects the power supply module 10. When the chip power supply voltage is too low, the undervoltage lockout module 20 sends a REST instruction to reset the integral loop control module to prevent the control circuit from not working properly when the power is turned on again; the bandgap reference module 30 is connected to the power supply module 10 to provide a reference voltage V for the loop integral control module 40 REF The loop integration control module 40 controls the reference voltage V REF With the sampling voltage V CS The control driving module 70 controls the power tube Q1 to work.

[0035] The AC power voltage may fluctuate during the transmission process. When the AC power voltage increases, even after pre-processing by rectification and filtering, a peak of the operating voltage will eventually form at both ends of the LED module, causing a large instantaneous current. The loop integral control module 40 is essentially an amplifier, and its passband bandwidth is usually only a few hertz or tens of hertz. It will be distorted at other frequencies and cannot play an amplification role. When the instantaneous current is too large, the loop integral control module 40 cannot respond, and it is easy to have a long-term large current, causing damage to the control circuit.

[0036] In order to solve the above problems, the first embodiment of the present disclosure provides an LED dual-loop control circuit, and its connection diagram is as follows: Figure 2 The dual-loop control circuit mainly includes a power module 10, a loop integral control module 40, an LED load 50 and a fast response module 60, wherein the input end of the power module 10 is connected to the bus (mains), the input end of the loop integral control module 40 is connected to the output end of the power module 10 and the sampling resistor R csThe first end of the LED load 50 is connected to the bus, and the second end of the LED load is connected to the sampling resistor R through the power tube Q1. cs The first end of the sampling resistor R cs The second end of the ground; the fast response module 60 can replace the role of the driving module, its input end and the output end of the loop integral control module 40 and the sampling resistor R cs The first end of each of the loop integral control module 40 and the sampling resistor R are connected respectively, and the output end thereof is connected to the gate of the power tube Q1. The ... sampling resistor R cs The sampling parameters drive the power tube Q1 to be turned on and off, for example, through the output voltage V of the loop integral control module 40 R And the sampling resistor R cs The sampling voltage V cs The size between , drives the power tube Q1 to be on and off. Specifically, the sampling parameter can be the sampling voltage V cs , or the sampling current I through the sampling resistor cs The first reference value is usually the output voltage V output by the loop integral control module. R .

[0037] In actual use, the LED dual-loop control circuit may further include an undervoltage lockout module 20 and a bandgap reference module 30, such as Figure 3 As shown, they respectively play the role of low-voltage protection of the circuit and the role of providing a reference voltage, wherein the output end of the power supply module 10 is connected to the undervoltage lockout module 20 and the bandgap reference module 30 respectively, the input end of the loop integral control module 40 is also connected to the output end of the undervoltage lockout module 20 and the output end of the bandgap reference module 30 respectively, and the input end of the fast response module 60 is also connected to the output end of the undervoltage lockout module 20.

[0038] In this embodiment, a fast response module is added to the traditional loop integral control LED circuit. The fast response module 60 is connected to the loop integral control module 40 and the sampling resistor R cs are connected separately, which has a larger bandwidth than the loop integral control module 40, based on the sampling resistor R cs The rapid response module 60 can obtain the sampling parameters based on the sampling parameters R cs The first reference value realizes fast on-off control of the power tube Q1, thereby playing an overall protection role for the LED circuit and improving the reliability of the circuit.

[0039] Figure 4 A first preferred implementation of the LED dual-loop control circuit is shown, as Figure 4As shown, the fast response module 60 at least includes an operational amplifier AMP1, a first input terminal of the operational amplifier AMP1 is connected to the output terminal of the loop control module 40, and is used to receive the first reference value output by the loop control module 40, and a second input terminal of the operational amplifier AMP1 is connected to the sampling resistor R cs The first end is connected to receive the sampling resistor R cs The output terminal of the operational amplifier AMP1 is connected to the gate of the power tube Q1, and the on-off control of the power tube Q1 is realized based on the comparison result between the first reference value and the sampling parameter. It should be noted that when the circuit is connected, the driving of different types of power tubes Q1 can be realized by adjusting the input contents of the two input terminals of the operational amplifier AMP1.

[0040] Figure 4 The positive input terminal of the operational amplifier AMP1 is connected to the output terminal of the loop control module 40, and the negative input terminal is connected to the sampling resistor R cs The first end is connected to the power tube Q1, at this time, the power tube Q1 is an N-MOS tube, that is, it is turned on when a high-level voltage is applied to the gate and turned off when a low voltage is applied. cs If the sampling voltage V cs Greater than the output voltage V R , the input value of the negative input terminal of the operational amplifier AMP1 is greater than the input value of the positive input terminal, the operational amplifier AMP1 will reduce or even turn off the voltage V output by its output terminal gate , because its output end is connected to the gate of N-MOS tube, at V gate When the current is reduced or even turned off, the voltage applied to the gate of the power tube Q1 is reduced or no voltage is applied, gradually shutting off the path between the source and drain of the N-MOS tube, disconnecting the power tube, thereby limiting the instantaneous current I cs The purpose is to prevent the instantaneous current I cs If the power tube Q1 used in the circuit is a P-MOS tube, the negative input terminal of the operational amplifier AMP1 is connected to the output terminal of the loop control module 40, and the positive input terminal is connected to the sampling resistor R cs The first end is connected to the sampling voltage V cs Greater than the output voltage V R When the power is on, the operational amplifier AMP1 outputs a high level signal to the gate of the P-MOS tube, causing the P-MOS tube to be gradually turned off.

[0041] Figure 5 A second preferred embodiment of the LED dual-loop control circuit is shown. Figure 4 Based on the circuit shown in the figure, a sampling resistor R is added csSpecifically, the quick response module 60 includes an operational amplifier AMP1, a comparator COMP1 and a timing unit, wherein the connection mode of the operational amplifier is similar to that of the timing unit. Figure 4 The first input terminal of the comparator COMP1 is connected to the output terminal of the bandgap reference module 30, and is used to receive the second reference value output by the bandgap reference module 30. The second input terminal of the comparator COMP1 is connected to the sampling resistor R cs The first end is connected to receive the sampling resistor R cs The input terminal of the timing unit is connected in series with the output terminal of the comparator COMP1, and its output terminal is connected to the input terminal of the loop integral control module 40; specifically, the timing unit mainly includes a timer Countor and an oscillation (OSC) module, such as Figure 5 As shown, the input end of the timer Countor is connected in series with the output end of the comparator COMP1, and its output end is connected to the input end of the loop integral control module 40. The OSC module is connected in series with the timer Countor to provide a standard clock signal to the timer Countor. It should be understood that the second reference value output by the bandgap reference module 30 is usually a reference voltage V REF , is a stable voltage determined and output based on the mains; in this embodiment, the timing function is realized by the OSC module and the timer Countor, but in actual use, it is not limited to the use of the OSC module and the timer Countor, and any circuit that can achieve the timing effect can be applied in this embodiment.

[0042] like Figure 5 As shown, the sampling resistor R cs When short-circuited, the sampling voltage V cs The value approaches 0. At this time, the sampling voltage V cs Less than the reference voltage V REF , the comparator COMP1 outputs an activation signal EN to the timer Countor; the timer Countor starts to count the first time length when receiving the activation signal EN, and when the first time length exceeds the preset time length, the timer Countor outputs a reset signal REST1 to the loop integration control module 40; the loop integration control module 40 adjusts the output voltage of its output terminal to 0 based on the reset signal REST1; when the positive input terminal of the operational amplifier AMP1 is connected to the loop integration control module 40 and the negative input terminal is connected to the sampling resistor, the positive input V R is 0, and the negative input terminal is a sampling voltage V greater than 0 cs , in order to prevent the sampling resistor R cs Instantaneous current after short circuit I csIf the voltage is too large for a long time, the circuit will be damaged. The operational amplifier AMP1 will reduce or even shut down the voltage V output at its output terminal. gate , the voltage applied to the gate of the N-MOS tube is reduced or no longer applied, gradually shutting off the path between the source and drain of the power tube Q1, disconnecting the power tube, and thus achieving the purpose of protecting the circuit. Of course, when using the P-MOS tube as the power tube, the signals input to the two input terminals of the operational amplifier AMP1 can be reversed, that is, at V R Less than V cs In this case, the operational amplifier AMP1 outputs a high level to turn off the P-mos tube.

[0043] In addition, refer to Figure 5 In the connection mode of the circuit, the positive input terminal (first input terminal) of the comparator COMP1 is connected to the output terminal of the bandgap reference module 30, and the negative input terminal (second input terminal) is connected to the sampling resistor R cs The first end is connected to the reference voltage V output by the bandgap reference module 30 REF Greater than 0V and less than V when the circuit is working normally cs The peak value; when V cs Greater than V REF When the comparator COMP1 outputs a low level, when V cs Less than V REF When the sampling resistor R cs short circuit, at this time, the comparator COMP1 outputs a high level as the activation signal EN, and the timer Countor starts to count the first time length when receiving the activation signal EN, and compares it with the internal preset time length Tth, wherein the value of the preset time length Tth must be greater than or equal to one cycle T of the bus voltage after the bridge. In order to improve the reliability of the detection and prevent the LED circuit from being triggered to shut down by mistake, Tth can be set to K times T, where K is a real number greater than or equal to 1; when the first time length exceeds the preset time length Tth, the timer Countor outputs a REST1 signal to the loop integration control module 40, and the loop integration control module 40 is reset based on the REST1 signal, and its output voltage V R =0, and after being processed by the operational amplifier AMP1, the power tube Q1 is turned off and will not be released until the system is powered off and powered on again, thus reaching R cs The purpose of short circuit protection is to prevent R cs After short circuit I cs Excessive current for a long time may cause circuit damage.

[0044] In this embodiment, if Figure 5 In the connection mode, when the comparator COMP1 outputs a high level, the timer Countor starts timing. In actual use, the output signal of the comparator COMP1 can also be inverted, that is, when Vcs Voltage Ratio V REF When the voltage is high, the output EN of comparator COMP1 is high. cs Voltage Ratio V REF When the voltage is low, the output EN of the comparator COMP1 is at a low level, and EN is effective at a low level. The principle of its actual implementation has been described in detail in the previous text, and will not be repeated here. In addition, in this embodiment, a timer Countor is used to implement the timing function. In actual use, other circuits or components that can implement the timing function can also be selected, and this embodiment does not limit it.

[0045] The second embodiment of the present disclosure provides an LED dual-loop control method, which is mainly applied to the LED dual-loop control circuit provided in the first embodiment of the present disclosure. The flow chart of the control method is as follows: Figure 6 As shown, it mainly includes steps S1 and S2. It should be noted that the signal collection or flow and circuit control performed by other components in the circuit can be directly implemented using existing technologies, and this embodiment does not provide a specific description or limitation.

[0046] S1, obtain the sampling parameters of the sampling resistor.

[0047] S2, based on the comparison result between the sampling parameter and the first reference value, controlling the on and off of the power tube.

[0048] In this embodiment, the input end of the fast response module is connected to the output end of the loop integral control module, the output end of the undervoltage lockout module and the first end of the sampling resistor, and its output end is connected to the gate of the power tube. After the power is turned on, the fast response module can obtain the sampling voltage R at both ends of the sampling resistor in real time. cs As the sampling parameter, the output voltage V R As the first reference value, compare it with the sampling resistor R cs The sampling voltage V cs The size between them is determined based on the comparison result between the two, and the power tube Q1 is driven to be turned on and off.

[0049] In this embodiment, a fast response module is added to the traditional loop-integrated LED circuit. The fast response module is connected to the loop-integrated control module and the sampling resistor respectively. The fast response module has a larger bandwidth than the loop-integrated control module. Based on the acquisition of the sampling parameters of the sampling resistor, the fast response module can realize fast on-off control of the power tube based on the sampling parameters and the first reference value, thereby playing an overall protective role for the LED circuit and improving the reliability of the circuit.

[0050] Specifically, the fast response module can be implemented by an operational amplifier AMP1, a first input terminal of the operational amplifier AMP1 is connected to the output terminal of the loop control module, and is used to receive the first reference value output by the loop control module, and a second input terminal of the operational amplifier AMP1 is connected to the sampling resistor R cs The first end is connected to receive the sampling resistor R cs The sampling parameter of the operational amplifier AMP1 is connected to the gate of the power tube Q1. Based on the comparison result between the first reference value and the sampling parameter, the on-off control of the power tube Q1 is realized. It should be noted that when the circuit is connected, the driving of different types of power tubes Q1 can be realized by adjusting the content input to the two input terminals of the operational amplifier AMP1. The specific connection method and the principle of realizing the on-off of the power tube Q1 have been described in detail in the first embodiment, and will not be repeated in this embodiment.

[0051] Furthermore, after obtaining the sampling parameter of the sampling resistor, the duration of the sampling parameter being less than the second reference value can be counted. When the duration is greater than or equal to the preset duration, the power tube Q1 is turned off. Figure 7 Specifically, the fast response module may also include a timing unit and a comparator COMP1 to prevent the instantaneous current I cs On the basis of being too large, a sampling resistor R cs Fast response mechanism in case of short circuit, refer to Figure 5 Specifically, the first input terminal of the comparator COMP1 is connected to the output terminal of the bandgap reference module, and is used to receive the second reference value output by the bandgap reference module, which is usually a reference voltage V determined and output by the bandgap reference module based on the mains. REF The second input terminal of the comparator COMP1 is connected to the sampling resistor R cs The first end is connected to receive the sampling resistor R cs The sampling voltage V cs The input end of the timer Countor is connected in series with the output end of the comparator COMP1, and the output end of the timer Countor is connected to the input end of the loop integral control module.

[0052] In this embodiment, the sampling resistor R cs When short-circuited, the sampling voltage V cs The value approaches 0. At this time, the sampling voltage V cs Less than the reference voltage V REF, the comparator COMP1 outputs an activation signal EN to the timer Countor; the timer Countor starts to count the duration when receiving the activation signal EN, and when the duration exceeds the preset duration, the timer Countor outputs a reset signal REST1 to the loop integration control module; the loop integration control module adjusts the output voltage of its output terminal to 0 based on the reset signal REST1; when the positive input terminal of the operational amplifier AMP1 is connected to the loop integration control module 40 and the negative input terminal is connected to the sampling resistor, the positive input V R is 0, and the negative input terminal is a sampling voltage V greater than 0 cs , in order to prevent the sampling resistor R cs Instantaneous current after short circuit I cs If the voltage is too large for a long time, the circuit will be damaged. The operational amplifier AMP1 will reduce or even shut down the voltage V output at its output terminal. gate , the voltage applied to the gate of the power tube Q1 is reduced or no longer applied, gradually shutting off the path between the source and drain of the power tube Q1, disconnecting the power tube, and thus achieving the purpose of protecting the circuit. When using a P-MOS tube as a power tube, the signals input to the two input terminals of the operational amplifier AMP1 can be reversed, that is, at V R Less than V cs In this case, the operational amplifier AMP1 outputs a high level to turn off the P-mos tube.

[0053] Reference Figure 5 In the connection mode of the circuit, the positive input terminal (first input terminal) of the comparator COMP1 is connected to the output terminal of the bandgap reference module, and the negative input terminal (second input terminal) is connected to the sampling resistor R cs The first end is connected to the reference voltage V output by the bandgap reference module REF Greater than 0V and less than V when the circuit is working normally cs The peak value; when V cs Greater than V REF When the comparator COMP1 outputs a low level, when V cs Less than V REF When the sampling resistor R csshort circuit, at this time, the comparator COMP1 outputs a high level as the activation signal EN. The timer Countor starts to count the duration when receiving the activation signal EN, and compares it with the preset duration Tth set internally, wherein the value of the preset duration Tth must be greater than or equal to one cycle T of the bus voltage after the bridge. In order to improve the reliability of the detection and prevent the LED circuit from being triggered by mistake, Tth can be set to K times T, where K is a real number greater than or equal to 1; when the duration exceeds the preset duration Tth, the timer Countor outputs a REST1 signal to the loop integral control module, and the loop integral control module is reset based on the REST1 signal, and its output voltage V R =0, and after being processed by the operational amplifier AMP1, the power tube Q1 is turned off and will not be released until the system is powered off and powered on again, thus reaching R cs The purpose of short circuit protection is to prevent R cs After short circuit I cs Excessive current for a long time may cause circuit damage.

[0054] In this embodiment, if Figure 5 In the connection mode, when the comparator COMP1 outputs a high level, the timer Countor starts timing. In actual use, the output signal of the comparator COMP1 can also be inverted, that is, when V cs Voltage Ratio V REF When the voltage is high, the output EN of comparator COMP1 is high. cs Voltage Ratio V REF When the voltage is low, the output EN of the comparator COMP1 is at a low level, and EN is effective at a low level. The principle of its actual implementation has been described in detail in the previous text, and will not be repeated here. In addition, in this embodiment, a timer Countor is used to implement the timing function. In actual use, other circuits or components that can implement the timing function can also be selected, and this embodiment does not limit it.

[0055] The above embodiments are only exemplary embodiments of the present disclosure and are not intended to limit the present disclosure. The protection scope of the present disclosure is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present disclosure within the essence and protection scope of the present disclosure, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present disclosure.

Claims

1. An LED dual-loop control circuit, comprising: A power supply module, a loop integral control module and an LED load, wherein the input end of the power supply module is connected to a bus, the input end of the loop integral control module is respectively connected to the output end of the power supply module and the first end of a sampling resistor, the first end of the LED load is connected to the bus, the second end of the LED load is connected to the first end of the sampling resistor via a power tube, and the second end of the sampling resistor is grounded, characterized in that it also includes: A fast response module, wherein the input end of the fast response module is respectively connected to the output end of the loop integral control module and the first end of the sampling resistor, the output end of the fast response module is connected to the gate of the power tube, and the fast response module drives the power tube to be turned on and off based on the first reference value output by the loop integral control module and the sampling parameter of the sampling resistor; It also includes: an undervoltage lockout module and a bandgap reference module; wherein the output end of the power supply module is connected to the undervoltage lockout module and the bandgap reference module respectively, and the input end of the loop integral control module is connected to the output end of the undervoltage lockout module, the output end of the bandgap reference module and the first end of the sampling resistor respectively; The input end of the fast response module is also connected to the output end of the undervoltage lockout module; The rapid response module at least includes: an operational amplifier, wherein a first input terminal of the operational amplifier is connected to an output terminal of the loop integral control module and is used to receive a first reference value output by the loop integral control module, a second input terminal of the operational amplifier is connected to a first terminal of the sampling resistor and is used to receive a sampling parameter of the sampling resistor, and an output terminal of the operational amplifier is connected to a gate of the power tube; the operational amplifier controls the power tube based on a comparison result between the first reference value and the sampling parameter; A comparator, wherein a first input terminal of the comparator is connected to an output terminal of the bandgap reference module, and is used to receive a second reference value output by the bandgap reference module; and a second input terminal of the comparator is connected to a first terminal of the sampling resistor, and is used to receive a sampling parameter of the sampling resistor; A timing unit, wherein the input end of the timing unit is connected in series with the output end of the comparator, and the output end of the timing unit is connected to the input end of the loop integral control module.

2. The LED dual-loop control circuit according to claim 1, characterized in that: The timing unit at least comprises: A timer and an oscillation module; the input end of the timer is connected in series with the output end of the comparator, and the output end of the timer is connected to the input end of the loop integral control module; the oscillation module is connected in series with the timer to input a standard clock signal to the timer.

3. The LED dual-loop control circuit according to claim 1 or 2, characterized in that: When the sampling parameter input by the comparator is less than the second reference value, the comparator outputs an activation signal to the timing unit; The timing unit starts to count a first duration when receiving the activation signal, and when the first duration exceeds a preset duration, the timing unit outputs a reset signal to the loop integration control module; The loop integral control module adjusts the first reference value outputted by its output terminal to 0 based on the reset signal; The operational amplifier controls the power tube based on a comparison result between the first reference value and the sampling parameter.

4. A LED dual-loop control method, applied to the LED dual-loop control circuit according to any one of claims 1 to 3, characterized in that: include: Get the sampling parameters of the sampling resistor; Based on the comparison result between the sampling parameter and the first reference value, controlling the on and off of the power tube; Wherein, the first reference value is obtained through a loop integral control module.

5. The LED dual-loop control method according to claim 4, characterized in that: After obtaining the sampling parameters of the sampling resistor, the method further includes: When the sampling parameter is less than a second reference value and the duration is greater than or equal to a preset duration, turning off the power tube; The preset time duration is greater than or equal to one cycle of the post-bridge bus voltage.

6. The LED dual-loop control method according to claim 5, characterized in that: The second reference value is obtained by a bandgap reference module.

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