Self-adaptive two-stage control LED drive circuit

Abstract

The invention provides a self-adaptive two-stage control LED drive circuit, and the circuit comprises a rectifier bridge which is used for carrying out the rectification of a voltage signal of an input source, and outputting a first voltage signal, and the input source is an inductance type transformer or an electronic transformer; the input detection module is used for receiving the first voltage signal and distinguishing the type of the first voltage signal; the first-stage booster circuit is connected to the input detection module and is dynamically started or closed according to the type of the first voltage signal; the second-stage circuit is connected to the first-stage booster circuit or receives a first voltage signal through a bypass path and is used for driving an LED load; when the first-stage booster circuit is started, the boosted stable voltage is output to the second-stage circuit to drive the LED load, and when the first-stage booster circuit is closed, the second-stage circuit receives the first voltage signal through the bypass path to drive the LED load. The LED driving circuit provided by the embodiment of the invention can improve the compatibility of different input source types and reduce electromagnetic interference.

Description

Technical Field

[0001] This application relates to the technical field of lighting circuits, and particularly to an LED driving circuit with adaptive two-stage control. Background Art

[0002] In traditional LED lighting systems, LED driving circuits usually need to adapt to two types of input power supplies. One is an inductive transformer that outputs a 12VAC low-frequency alternating voltage. The other is an electronic transformer that outputs a 12VAC, 20kHz - 200kHz high-frequency alternating voltage. It is difficult for a single-stage circuit LED driving circuit to be compatible with an electronic transformer, and it is even more difficult to debug in electromagnetic interference tests. Usually, directly adding a capacitor to the input will affect the operation of the electronic transformer, resulting in mismatched dimming.

[0003] In the prior art, usually a MOS tube is connected to judge. When the input is an inductive transformer, a capacitor is connected, and when the input is an electronic transformer, the MOS tube is turned off and the capacitor is disconnected. In this way, since the first stage still operates in a high-frequency signal switch, the capacitive load connected cannot effectively solve the electromagnetic interference problem. Therefore, due to the significant differences in the voltage characteristics, frequencies, and load requirements of the two input sources, it is difficult for a single circuit to be compatible with both. Summary of the Invention

[0004] The purpose of this application is to provide an LED driving circuit with adaptive two-stage control, which can improve the compatibility of different input source types and reduce electromagnetic interference.

[0005] To solve the above technical problems, an embodiment of this application provides an LED driving circuit with adaptive two-stage control, including: a rectifier bridge for rectifying the voltage signal of the input source and outputting a first voltage signal, where the input source is an inductive transformer or an electronic transformer; an input detection module for receiving the first voltage signal and distinguishing the type of the first voltage signal; a first-stage boost circuit connected to the input detection module and dynamically starting or shutting down according to the type of the first voltage signal; a second-stage circuit connected to the first-stage boost circuit or receiving the first voltage signal through a bypass path for driving an LED load; wherein, when the first-stage boost circuit starts, it outputs a boosted stable voltage to the second-stage circuit to drive the LED load, and when the first-stage boost circuit shuts down, the second-stage circuit receives the first voltage signal through the bypass path to drive the LED load.

[0006] In one embodiment, the input detection module includes a voltage division circuit and a comparator; the voltage division circuit includes two serially connected first resistors and a second resistor, and is configured to divide the voltage of the first voltage signal to generate a second voltage signal; the inverting terminal of the comparator receives the second voltage signal, the non-inverting terminal is connected to a preset threshold voltage, and the output terminal is connected to the enable pin of the first-stage boost circuit; the comparator outputs a control signal according to the comparison result between the second voltage signal and the preset threshold voltage signal to control the startup or shutdown of the first-stage boost circuit.

[0007] In one embodiment, the comparator outputs a control signal according to the comparison result between the second voltage signal and the preset threshold voltage signal to control the startup or shutdown of the first-stage boost circuit, including: when the second voltage is less than the preset threshold voltage, the comparator outputs a high level to start the first-stage boost circuit; when the second voltage is greater than the preset threshold voltage, the comparator outputs a low level to shut down the first-stage boost circuit.

[0008] In one embodiment, according to the differences in the voltage signals of different input sources, the ratio of the first resistor to the second resistor is set to control the voltage division ratio.

[0009] In one embodiment, the ratio of the first resistor to the second resistor is in the range of [5, 30].

[0010] In one embodiment, when the input source is an electronic transformer, the first-stage boost circuit starts up and outputs a stabilized boosted voltage to the second-stage circuit to drive the LED load.

[0011] In one embodiment, when the input source is an inductive transformer, the first-stage boost circuit is shut down, and the second-stage circuit receives the first voltage signal through a diode to drive the LED load, so as to avoid the switching loss of the first-stage boost circuit.

[0012] In one embodiment, when the input source is an inductive transformer, a capacitor is connected to the input terminal of the second-stage circuit as a matching capacitive load to reduce electromagnetic interference.

[0013] In one embodiment, the second-stage circuit is a boost constant-current circuit or a buck constant-current circuit, and is configured to adjust the output current according to the input source type to drive the LED load.

[0014] In one embodiment, the first-stage boost circuit and the second-stage circuit share some components to reduce redundant hardware configuration and lower the BOM cost.

[0015] The adaptive two-stage controlled LED driving circuit in the embodiments of the present application has the following advantages over the prior art: 1. The input detection module can automatically distinguish the type of the first voltage signal, thereby further distinguishing the input source type, such as inductive transformer or electronic transformer input, and dynamically adjusting the working mode accordingly, enabling good compatibility with different input source types.

[0016] 2. When the first - stage boost circuit starts, it outputs a stable boosted voltage to the second - stage circuit to drive the LED load. At this time, the first - stage boost circuit and the second - stage circuit work together. The first - stage boost circuit provides a stable bus voltage for the second - stage circuit, ensuring the constant - current accuracy of the second - stage circuit and avoiding radiation interference caused by voltage fluctuations.

[0017] 3. When the first - stage boost circuit is turned off, the second - stage circuit receives the first voltage signal through a bypass path to drive the LED load, reducing switching losses, lowering electromagnetic interference, and optimizing the electromagnetic compatibility performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, unless otherwise stated. The drawings in the figures do not constitute a scale limitation.

[0019] Figure 1 is a schematic structural diagram of an adaptive two - stage controlled LED driving circuit according to an embodiment of the present application; Figure 2 is a schematic structural diagram of an adaptive two - stage controlled LED driving circuit according to another embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the above - mentioned objects, features, and advantages of the present application more obvious and understandable, the following detailed description of the specific embodiments of the present application is provided in conjunction with the drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0021] In addition, if the terms "first" and "second" appear, these terms are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0022] The first embodiment of the present invention relates to an LED driving circuit with adaptive two-stage control, as Figure 1 shown: It includes: a rectifier bridge 101, which is used to rectify the voltage signal of the input source and output a first voltage signal, and the input source is an inductive transformer or an electronic transformer; an input detection module 102, which is used to receive the first voltage signal and distinguish the type of the first voltage signal; a first-stage boost circuit 103, which is connected to the input detection module 102 and is dynamically started or shut down according to the type of the first voltage signal; a second-stage circuit 104, which is connected to the first-stage boost circuit 103 or receives the first voltage signal through a bypass path and is used to drive an LED load; wherein, when the first-stage boost circuit 103 is started, it outputs a boosted stable voltage to the second-stage circuit 104 to drive the LED load, and when the first-stage boost circuit 103 is shut down, the second-stage circuit 104 receives the first voltage signal through the bypass path to drive the LED load.

[0023] In the embodiment of the present application, the input source is an inductive transformer or an electronic transformer, which provides electrical energy input for the entire circuit. The rectifier bridge 101 includes four diodes connected in a bridge configuration and is used to rectify the voltage signal of the input source. By utilizing the unidirectional conductivity of the diodes, it converts the positive and negative alternating AC voltage into a unidirectional DC voltage (i.e., the first voltage signal). Optionally, as Figure 1As shown in the figure, the input detection module 102 may include a voltage dividing circuit and a comparator U1. The voltage dividing circuit includes two series-connected first resistors Ru and second resistors Rd, which are used to divide the first voltage signal to generate a second voltage Vsence signal. The inverting terminal of the comparator U1 receives the second voltage Vsence signal, the non-inverting terminal is connected to a preset threshold voltage Vref, and the output terminal is connected to the enable pin of the first-stage boost circuit 103. The comparator U1 outputs a control signal according to the comparison result of the second voltage Vsence signal and the preset threshold voltage Vref signal to control the startup or shutdown of the first-stage boost circuit 103. In the embodiments of the present application, since the types of input sources are different, for example: the inductive transformer outputs a 12VAC low-frequency AC voltage, and the electronic transformer outputs a 12VAC, 20kHz - 200kHz high-frequency AC voltage. Therefore, the types of the first voltage signals input by different input source types are also different. Furthermore, the enabling results of the comparator U1 based on the second voltage Vsence signal generated after dividing the first voltage signal are also different. Based on this, the input detection module 102 can distinguish the types of the first voltage signals. Specifically, the second voltage Vsence can be compared with the preset threshold voltage Vref. When the second voltage Vsence is less than the preset threshold voltage Vref, the comparator U1 outputs a high level to start the first-stage boost circuit 103. When the second voltage Vsence is greater than the preset threshold voltage Vref, the comparator U1 outputs a low level to turn off the first-stage boost circuit 103. For example, when the input source is an electronic transformer, the second voltage Vsense is less than the preset threshold voltage Vref, and the comparator U1 outputs a high level to start the first-stage boost circuit 103. The first-stage boost circuit 103 outputs a stable voltage to the second-stage circuit 104. The second-stage circuit 104 serves as a high-frequency switching constant current source to match the inductive load requirements of the electronic transformer and avoid LED flickering. When the input source is an inductive transformer, the second voltage Vsense is greater than the preset threshold voltage Vref, the comparator U1 outputs a low level, and the first-stage boost circuit 103 is turned off. The second-stage circuit 104 receives the first voltage signal through a bypass path (such as a diode Df) to drive the LED load to avoid the switching loss of the first-stage boost circuit 103.

[0024] The first - stage boost circuit 103 in the embodiments of the present application includes a boost integrated circuit (Boost IC) U3, which integrates control logic and a drive circuit inside. By controlling the conduction and cutoff of an external switching transistor (such as MOS transistor Q1), the boost function is realized. In the embodiments of the present application, the first - stage boost circuit 103 is connected to the input detection module 102 and is dynamically started or shut down according to the type of the first voltage signal; the second - stage circuit 104 is connected to the first - stage boost circuit 103 or receives the first voltage signal through a bypass path (such as diode Df) and is used to drive an LED load; wherein, when the first - stage boost circuit 103 is started, it outputs a stable boosted voltage to the second - stage circuit 104 to drive the LED load, and when the first - stage boost circuit 103 is shut down, the second - stage circuit 104 receives the first voltage signal through the bypass path to drive the LED load.

[0025] Compared with the prior art, in the embodiments of the present application, the input detection module 102 can automatically distinguish the type of the first voltage signal, and further distinguish the input source type. For example, the input source type is inductive transformer input or electronic transformer input, and the working mode is dynamically adjusted accordingly. Therefore, different input source types can be well compatible. When the first - stage boost circuit 103 is started, it outputs a stable boosted voltage to the second - stage circuit 104 to drive the LED load. At this time, the first - stage boost circuit 103 and the second - stage circuit 104 work together. The first - stage boost circuit 103 provides a stable bus voltage for the second - stage circuit 104 to ensure the constant - current accuracy of the second - stage circuit 104 and avoid radiation interference caused by voltage fluctuations. When the first - stage boost circuit 103 is shut down, the second - stage circuit 104 receives the first voltage signal through the bypass path to drive the LED load, reducing switching losses, lowering electromagnetic interference, and optimizing electromagnetic compatibility.

[0026] In an optional embodiment, the second - stage circuit 104 can be a boost constant - current circuit or a buck constant - current circuit, and the output current can be specifically adjusted according to the input source type to drive the LED load. Figure 1 Taking the second - stage circuit 104 as a boost constant - current circuit as an example for illustration. In this embodiment, as Figure 1As shown, the first - stage boost circuit 103 includes a boost integrated circuit U3, an MOS transistor Q1, an inductor L1, and a diode D1. The boost integrated circuit U3 is the core control component, which integrates control logic and a drive circuit inside. By controlling the on - and - off of the MOS transistor Q1, the boost function is achieved. When the MOS transistor Q1 is on, the inductor L1 stores energy; when the MOS transistor Q1 is off, the inductor L1 releases energy to boost the output voltage; at the same time, during the switching process of the MOS transistor Q1, it also participates in the storage and release of energy. The diode D1 is a free - wheeling diode. During the off - period of the MOS transistor Q1, it provides a free - wheeling path for the inductor current to prevent the reverse electromotive force generated by the inductor from damaging circuit components. Continuing to refer to Figure 1 , the second - stage circuit 104 includes a boost integrated circuit U4, an MOS transistor Q2, an inductor L2, a capacitor C2, and a diode D2. The boost integrated circuit U4 also integrates control logic and a drive circuit inside. By controlling the on - and - off of the MOS transistor Q2, the boost function is achieved. When the MOS transistor Q2 is on, the inductor L2 stores energy; when the MOS transistor Q2 is off, the inductor L2 releases energy, and cooperates with the capacitor C2, etc. to boost the output voltage. At the same time, during the switching process of the MOS transistor Q2, it also participates in the storage and release of energy. The capacitor C2 is used for filtering to reduce electromagnetic interference. The diode D2 is a free - wheeling diode. During the off - period of the MOS transistor Q2, it provides a free - wheeling path for the inductor current to prevent the reverse electromotive force generated by the inductor from damaging circuit components, and at the same time assists in transferring the inductor energy to the capacitor C2 and the load.

[0027] In addition, a voltage - dividing resistor R1, R2 can be connected between the first - stage boost circuit 103 and the second - stage circuit 104 to set the ratio of the output constant voltage; a resistor Rf can also be connected to feedback the potential of the output current of the second - stage circuit 104. The load LED is connected to the second - stage circuit 104, which converts electrical energy into light energy and provides illumination at a suitable working voltage.

[0028] In an alternative embodiment, according to the difference in voltage signals (such as amplitude) of different input sources, the resistance value of the second resistor Rd and the ratio of the first resistor Ru to the second resistor Rd can be set to control the voltage - dividing ratio. Preferably, the resistance value of the second resistor Rd is in the range of [2K, 10K], and the ratio of the first resistor Ru to the second resistor Rd is in the range of [5, 30].

[0029] In an alternative embodiment, the value of the second voltage Vsense is in the range of [0.3V, 2V].

[0030] In an alternative embodiment, when the reference value of the preset threshold voltage Vref is set at 12VAC input, the value of the preset threshold voltage Vref is in the range of [90%, 95%] of the value of the second voltage Vsense.

[0031] In one embodiment, when the input source is an inductive transformer, a capacitor C1 is connected to the input end of the second-stage circuit 104 as a matching capacitive load. The capacitor C1 is used for filtering, smoothing the output voltage, reducing voltage ripple, so as to reduce electromagnetic interference and make the output voltage more stable.

[0032] It should be noted that in practical applications, the non-inverting terminal of the comparator U1 can also receive the second voltage Vsence signal, the inverting terminal is connected to a preset threshold voltage Vref, and the output terminal is connected to the enable pin of the first-stage boost circuit 103. By setting the voltage division ratio of the voltage division circuit and the enable condition of the comparator U1, it is possible to distinguish the type of the first voltage signal based on the comparison result between the second voltage Vsence signal and the preset threshold voltage Vref.

[0033] In one embodiment, the first-stage boost circuit 103 and the second-stage circuit 104 share some components (such as diodes D1 and D2) to reduce redundant hardware configuration and lower the BOM cost.

[0034] In another alternative embodiment of the present application, as Figure 2 shown, a schematic structural diagram of another LED driving circuit with adaptive two-stage control is provided. Figure 2 The embodiment shown is substantially the same as the circuit structure in the embodiment Figure 1 shown. The difference is that Figure 2 the second-stage circuit 104 in the embodiment shown is a buck constant-current circuit. As Figure 2 shown, the second-stage circuit 104 includes: a buck integrated circuit Buck IC, a MOS transistor Q2, an inductor L2, and a diode D2. The buck integrated circuit Buck IC controls the on and off times of the MOS transistor Q2, adjusts the working state of the buck circuit, and realizes stable bucking. The MOS transistor Q2 is periodically turned on and off under the control of the buck integrated circuit Buck IC, controlling the charging and discharging process of the inductor L2. The inductor L2 stores energy when the MOS transistor Q2 is turned on and releases energy when the MOS transistor Q2 is turned off, and cooperates with other components to achieve the bucking function. The diode D2 provides a freewheeling path for the inductor L2 when the MOS transistor Q2 is turned off, maintaining current continuity. The LED, as a load, is powered by the stable DC voltage output by the buck circuit to emit light. The rectifier bridge 101, the input detection module 102, and the first-stage boost circuit 103 in this embodiment are the same as those in Figure 1The circuit structures in the illustrated embodiments are the same. When the input source is an electronic transformer, the second voltage Vsense is less than the preset threshold voltage Vref, and the comparator U1 outputs a high level to start the first-stage boost circuit 103. The first-stage boost circuit 103 outputs a stable voltage to the second-stage circuit 104. The second-stage circuit 104 serves as a high-frequency switch constant current source to match the inductive load requirements of the electronic transformer and avoid LED flicker. When the input source is an inductive transformer, the second voltage Vsense is greater than the preset threshold voltage Vref, the comparator U1 outputs a low level, and the first-stage boost circuit 103 is turned off. The second-stage circuit 104 receives the first voltage signal through a bypass path (such as the diode Df) to drive the LED load, so as to avoid the switching loss of the first-stage boost circuit 103.

[0035] Compared with the prior art, in the embodiments of the present application, the input detection module 102 can automatically distinguish the type of the first voltage signal, and further distinguish the type of the input source, such as whether the input source type is an inductive transformer input or an electronic transformer input, so as to dynamically adjust the working mode. Therefore, it can be well compatible with different input source types. When the first-stage boost circuit 103 is started, it outputs a boosted stable voltage to the second-stage circuit 104 to drive the LED load. At this time, the first-stage boost circuit 103 and the second-stage circuit 104 work together. The first-stage boost circuit 103 provides a stable bus voltage for the second-stage circuit 104 to ensure the constant current accuracy of the second-stage circuit 104 and avoid radiation interference caused by voltage fluctuations. When the first-stage boost circuit 103 is turned off, the second-stage circuit 104 receives the first voltage signal through a bypass path to drive the LED load, reducing switching losses, reducing electromagnetic interference, and optimizing electromagnetic compatibility.

[0036] The adaptive two-stage control LED driving circuit in the embodiments of the present application is applicable to MR16 LED lamps and is compatible with traditional halogen lamp electronic transformer and inductive transformer input systems.

[0037] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0038] The above-described embodiments only represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

[0039] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present invention, and in actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the present invention.

Claims

1. An LED driving circuit with adaptive two - stage control, characterized in that, Comprising: A rectifier bridge for rectifying the voltage signal of the input source and outputting a first voltage signal, where the input source is an inductive transformer or an electronic transformer; An input detection module for receiving the first voltage signal and differentiating the type of the first voltage signal; A first-stage boost circuit connected to the input detection module and dynamically started or shut down according to the type of the first voltage signal; A second-stage circuit connected to the first-stage boost circuit or receiving the first voltage signal through a bypass path for driving an LED load; Wherein, when the first-stage boost circuit is started, it outputs a boosted stable voltage to the second-stage circuit to drive the LED load, and when the first-stage boost circuit is shut down, the second-stage circuit receives the first voltage signal through the bypass path to drive the LED load.

2. The LED driving circuit according to claim 1, wherein The input detection module includes a voltage-dividing circuit and a comparator; The voltage-dividing circuit includes two serially-connected first resistors and a second resistor for dividing the voltage of the first voltage signal to generate a second voltage signal; The inverting terminal of the comparator receives the second voltage signal, the non-inverting terminal is connected to a preset threshold voltage, and the output terminal is connected to the enable pin of the first-stage boost circuit; The comparator outputs a control signal according to the comparison result between the second voltage signal and the preset threshold voltage signal to control the start or shutdown of the first-stage boost circuit.

3. The LED driving circuit according to claim 2, wherein, The comparator outputs a control signal according to the comparison result between the second voltage signal and the preset threshold voltage signal to control the start or shutdown of the first-stage boost circuit, including: When the second voltage is less than the preset threshold voltage, the comparator outputs a high level to start the first-stage boost circuit; when the second voltage is greater than the preset threshold voltage, the comparator outputs a low level to shut down the first-stage boost circuit.

4. The LED driving circuit according to claim 2, wherein Set the ratio of the first resistor and the second resistor according to the difference in the voltage signals of different input sources to control the voltage-dividing ratio.

5. The LED driving circuit according to claim 4, wherein The ratio of the first resistor and the second resistor is within [5, 30].

6. The LED driving circuit according to claim 1, wherein When the input source is an electronic transformer, the first-stage boost circuit is started and outputs a boosted stable voltage to the second-stage circuit to drive the LED load.

7. The LED driving circuit according to claim 1, wherein When the input source is an inductive transformer, the first-stage boost circuit is shut down, and the second-stage circuit receives the first voltage signal through a diode to drive the LED load to avoid the switching loss of the first-stage boost circuit.

8. The LED driving circuit according to claim 7, wherein When the input source is an inductive transformer, a capacitor is connected to the input end of the second-stage circuit as a matching capacitive load to reduce electromagnetic interference.

9. The LED driving circuit according to claim 1, wherein The second-stage circuit is a boost constant-current circuit or a buck constant-current circuit for adjusting the output current according to the input source type to drive the LED load.

10. The LED driving circuit according to claim 1, wherein The first-stage boost circuit and the second-stage circuit share some components to reduce redundant hardware configuration and lower the BOM cost.

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