An adaptive two-stage control LED driver circuit

Abstract

The present application provides an adaptive two-stage controlled LED driver circuit, comprising: a rectifier bridge for rectifying a voltage signal from an input source, such as an inductive transformer or an electronic transformer, and outputting a first voltage signal; 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 activated or deactivated based on the type of the first voltage signal; and a second-stage circuit connected to the first-stage boost circuit or receiving the first voltage signal via a bypass path for driving an LED load. When the first-stage boost circuit is activated, it outputs a boosted, stable voltage to the second-stage circuit to drive the LED load. When the first-stage boost circuit is deactivated, the second-stage circuit receives the first voltage signal via a bypass path to drive the LED load. The LED driver circuit of the present application can improve compatibility with different input source types and reduce electromagnetic interference.

Description

Technical Field

[0001] The present application relates to the technical field of lighting circuits, and in particular to an adaptive two-stage controlled LED driving circuit. Background Art

[0002] In traditional LED lighting systems, LED driver circuits typically need to adapt to two types of input power sources: an inductive transformer that outputs a low-frequency 12VAC AC voltage, and an electronic transformer that outputs a high-frequency 12VAC AC voltage of 20kHz-200kHz. Single-stage LED driver circuits present challenges with electronic transformer compatibility, making them even more difficult to debug during electromagnetic interference testing. Directly adding a capacitor to the input often interferes with the electronic transformer's operation, resulting in dimming mismatches.

[0003] In existing technology, a MOSFET is typically connected to determine the input voltage. If the input is an inductive transformer, a capacitor is connected. If the input is an electronic transformer, the MOSFET is turned off, disconnecting the capacitor. In this approach, because the first stage still operates as a high-frequency signal switch, the connected capacitive load does not effectively address electromagnetic interference. Therefore, due to the significant differences in the voltage characteristics, frequency, and load requirements of the two input sources, a single circuit is difficult to simultaneously accommodate both. Summary of the Invention

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

[0005] To solve the above technical problems, an embodiment of the present application provides an adaptive two-stage controlled LED driving circuit, comprising: a rectifier bridge, for rectifying the voltage signal of an input source and outputting a first voltage signal, wherein 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 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, the boosted stable voltage is output 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 a bypass path to drive the LED load.

[0006] In one embodiment, the input detection module includes a voltage divider circuit and a comparator; the voltage divider circuit includes two first resistors and a second resistor connected in series, which are used to divide the first voltage signal to generate a second voltage signal; the reverse end of the comparator receives the second voltage signal, the non-inverting end is connected to a preset threshold voltage, and the output end is connected to the enable pin of the first-stage boost circuit; the comparator outputs a control signal based on the comparison result of the second voltage signal and the preset threshold voltage signal to control the first-stage boost circuit to start or shut down.

[0007] In one embodiment, the comparator outputs a control signal based on the comparison result between the second voltage signal and the preset threshold voltage signal to control the start or shut down 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, the ratio of the first resistor to the second resistor is set according to the difference in voltage signals from different input sources to control the voltage division ratio.

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

[0010] In one embodiment, when the input source is an electronic transformer, the first-stage boost circuit is activated and outputs a boosted stable 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 turned off, and the second-stage circuit receives the first voltage signal through a diode to drive an LED load, thereby avoiding switching losses 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 end of the second-stage circuit as a matching capacitive load to reduce electromagnetic interference.

[0013] In one embodiment, the second stage circuit is a step-up constant current circuit or a step-down constant current circuit, which is used 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 reuse some components to reduce redundant hardware configuration and lower BOM cost.

[0015] The adaptive two-stage control LED driver circuit in the embodiment of the present application has the following advantages over the prior art:

[0016] 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, so as to dynamically adjust the working mode and be well compatible with different input source types.

[0017] 2. When the first-stage boost circuit starts, it outputs a boosted, stable voltage to the second-stage circuit to drive the LED load. At this point, the first-stage boost circuit works in conjunction with the second-stage circuit to provide a stable bus voltage for the second-stage circuit, ensuring the second-stage circuit's constant current accuracy and preventing radiation interference caused by voltage fluctuations.

[0018] 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, thereby reducing switching loss, lowering electromagnetic interference, and optimizing electromagnetic compatibility performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0020] Figure 1 1 is a schematic structural diagram of an adaptive two-stage controlled LED driving circuit according to an embodiment of the present application;

[0021] Figure 2 3 is a structural diagram of an adaptive two-stage controlled LED driving circuit according to another embodiment of the present application. DETAILED DESCRIPTION

[0022] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0023] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0024] The first embodiment of the present invention relates to an adaptive two-stage controlled LED driving circuit, such as Figure 1 As shown: it includes: a rectifier bridge 101, used to rectify the voltage signal of the input source and output a first voltage signal, wherein the input source is an inductive transformer or an electronic transformer; an input detection module 102, used to receive the first voltage signal and distinguish the type of the first voltage signal; a first-stage boost circuit 103, connected to the input detection module 102, and dynamically started or shut down according to the type of the first voltage signal; a second-stage circuit 104, connected to the first-stage boost circuit 103 or receiving the first voltage signal through a bypass path, for driving 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 a bypass path to drive the LED load.

[0025] In the embodiment of the present application, the input source is an inductive transformer or an electronic transformer, which provides power input for the entire circuit. The rectifier bridge 101 includes four bridge-connected diodes, which are used to rectify the voltage signal of the input source. It uses the unidirectional conductivity of the diodes to convert the alternating positive and negative AC voltage into a unidirectional DC voltage (i.e., the first voltage signal). Figure 1As shown in , the input detection module 102 may include a voltage divider circuit and a comparator U1. The voltage divider circuit includes two first resistors Ru and a second resistor Rd connected in series, and is used to divide the first voltage signal to generate a second voltage Vsence signal. The comparator U1 receives the second voltage Vsence signal at its inverting terminal, connects to a preset threshold voltage Vref at its non-inverting terminal, and connects to the enable pin of the first-stage boost circuit 103 at its output terminal. The comparator U1 outputs a control signal based on the comparison result between the second voltage Vsence signal and the preset threshold voltage Vref signal to control the activation or deactivation of the first-stage boost circuit 103. In the embodiment of the present application, due to different types of input sources, for example, an inductive transformer outputs a 12VAC low-frequency AC voltage, and an electronic transformer outputs a 12VAC, 20kHz-200kHz high-frequency AC voltage. Therefore, different input source types have different types of input first voltage signals, and thus the second voltage Vsence signal generated after the voltage division of the first voltage signal also has different enabling results for the comparator U1. Based on this, the input detection module 102 can distinguish the type of the first voltage signal. 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 activate 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 deactivate 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 activate the first-stage boost circuit 103. The first-stage boost circuit 103 outputs a stable voltage to the second-stage circuit 104, which acts as a high-frequency switching constant current source to match the inductive load requirements of the electronic transformer and prevent LED flicker. When the input source is an inductive transformer, the second voltage Vsense is greater than the preset threshold voltage Vref, and the comparator U1 outputs a low level, deactivating the first-stage boost circuit 103. The second stage circuit 104 receives the first voltage signal through a bypass path (such as a diode Df) to drive an LED load, thereby avoiding switching loss of the first stage boost circuit 103 .

[0026] The first-stage boost circuit 103 in the embodiment of the present application includes a boost integrated circuit (Boost IC) U3, which integrates control logic and drive circuits, and realizes the boost function by controlling the conduction and shutdown of the external switch tube (such as the MOS tube Q1). In the embodiment 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 a diode Df) for driving the LED load; wherein, when the first-stage boost circuit 103 is started, the boosted stable voltage is output to the second-stage circuit 104 to drive the LED load, and 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.

[0027] Compared to the prior art, the embodiment of the present application can automatically distinguish the type of the first voltage signal through the input detection module 102, thereby further distinguishing the input source type, such as whether the input source type is an inductive transformer input or an electronic transformer input, thereby dynamically adjusting the working mode, and thus being well compatible with different input source types. When the first-stage boost circuit 103 is started, it outputs the 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 in coordination, and the first-stage boost circuit 103 provides a stable bus voltage to the second-stage circuit 104, ensuring the constant current accuracy of the second-stage circuit 104 and avoiding 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.

[0028] In an optional embodiment, the second stage circuit 104 may be a boost constant current circuit or a buck constant current circuit, and may specifically adjust the output current to drive the LED load according to the input source type. Figure 1 The second stage circuit 104 is taken as an example to illustrate the boost constant current circuit. Figure 1As shown in , the first-stage boost circuit 103 includes a boost integrated circuit U3, a MOS tube Q1, an inductor L1, and a diode D1. The boost integrated circuit U3 is the core control component, which integrates the control logic and the drive circuit. It realizes the boost function by controlling the on and off of the MOS tube Q1. When the MOS tube Q1 is turned on, the inductor L1 stores energy; when the MOS tube Q1 is turned off, the inductor L1 releases energy to increase the output voltage; at the same time, during the switching process of the MOS tube Q1, it also participates in the storage and release of energy. The diode D1 is a freewheeling diode. During the period when the MOS tube Q1 is turned off, it provides a freewheeling loop for the inductor current to prevent the reverse electromotive force generated by the inductor from damaging the circuit components. Continue to refer to Figure 1 The second-stage circuit 104 includes a boost integrated circuit U4, a MOS transistor Q2, an inductor L2, a capacitor C2, and a diode D2. The boost integrated circuit U4 also integrates control logic and drive circuitry, achieving a boost function by controlling the on and off states of the MOS transistor Q2. When the MOS transistor Q2 is on, the inductor L2 stores energy; when the MOS transistor Q2 is off, the inductor L2 releases energy, working with capacitor C2 and other components to increase the output voltage. It also participates in the storage and release of energy during the switching process of the MOS transistor Q2. Capacitor C2 is used for filtering to reduce electromagnetic interference. Diode D2 is a freewheeling diode. When the MOS transistor Q2 is off, it provides a freewheeling circuit for the inductor current, preventing the reverse electromotive force generated by the inductor from damaging circuit components. It also helps transfer the inductor energy to capacitor C2 and the load.

[0029] Furthermore, voltage-dividing resistors R1 and 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 provide feedback on the output current potential of the second-stage circuit 104. A load LED connected to the second-stage circuit 104 converts electrical energy into light energy, providing illumination at a suitable operating voltage.

[0030] In an optional embodiment, the resistance value of the second resistor Rd and the ratio of the first resistor Ru to the second resistor Rd can be set based on the difference in voltage signals (such as amplitude) from different input sources to control the voltage division 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].

[0031] In an optional embodiment, the value of the second voltage Vsense is in the range of [0.3V, 2V].

[0032] In an optional embodiment, the reference value of the preset threshold voltage Vref is set at [90%, 95%] of the second voltage Vsense value when the input is 12VAC.

[0033] In one embodiment, when the input source is an inductive transformer, the input end of the second-stage circuit 104 is connected to a capacitor C1 as a matching capacitive load. The capacitor C1 is used for filtering, smoothing the output voltage, reducing voltage ripple, reducing electromagnetic interference, and making the output voltage more stable.

[0034] It should be noted that, in actual applications, the comparator U1 can also receive the second voltage Vsence signal at the same direction end, connect the inverting end to the preset threshold voltage Vref, and connect the output end to the enable pin of the first-stage boost circuit 103. By setting the voltage division ratio of the voltage divider 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.

[0035] In one embodiment, the first-stage boost circuit 103 and the second-stage circuit 104 reuse some components (such as diodes D1 and D2 ) to reduce redundant hardware configuration and lower BOM cost.

[0036] In another optional embodiment of the present application, Figure 2 As shown in , another structural diagram of an adaptive two-stage control LED driver circuit is provided. Figure 2 The embodiment shown is Figure 1 The circuit structures in the embodiments shown are substantially the same, except that: Figure 2 In the embodiment shown, the second stage circuit 104 is a step-down constant current circuit. Figure 2 As shown in , the second-stage circuit 104 includes: a buck integrated circuit Buck IC, a MOS tube Q2, an inductor L2, and a diode D2. The buck integrated circuit Buck IC controls the on and off time of the MOS tube Q2, adjusts the working state of the buck circuit, and realizes stable buck. Under the control of the buck integrated circuit Buck IC, the MOS tube Q2 is periodically turned on and off to control the charging and discharging process of the inductor L2. The inductor L2 stores energy when the MOS tube Q2 is turned on, and releases energy when the MOS tube Q2 is turned off, and cooperates with other components to realize the buck function. When the MOS tube Q2 is turned off, the diode D2 provides a freewheeling path for the inductor L2 to maintain current continuity. The LED serves as a load and 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 connected to the rectifier bridge 101, the input detection module 102, and the first-stage boost circuit 103. Figure 1The circuit structure in the illustrated embodiment is the same. When the input source is an electronic transformer, and the second voltage Vsense is less than the preset threshold voltage Vref, comparator U1 outputs a high level to activate the first-stage boost circuit 103. The first-stage boost circuit 103 outputs a stable voltage to the second-stage circuit 104, which acts as a high-frequency switching constant current source to match the inductive load requirements of the electronic transformer and prevent LED flicker. When the input source is an inductive transformer, and the second voltage Vsense is greater than the preset threshold voltage Vref, comparator U1 outputs a low level, shutting down the first-stage boost circuit 103. The second-stage circuit 104 receives the first voltage signal through a bypass path (such as diode Df) to drive the LED load, thereby avoiding switching losses in the first-stage boost circuit 103.

[0037] Compared to the prior art, the embodiment of the present application can automatically distinguish the type of the first voltage signal through the input detection module 102, thereby further distinguishing the input source type, such as whether the input source type is an inductive transformer input or an electronic transformer input, thereby dynamically adjusting the working mode, and thus being well compatible with different input source types. When the first-stage boost circuit 103 is started, it outputs the 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 in coordination, and the first-stage boost circuit 103 provides a stable bus voltage to the second-stage circuit 104, ensuring the constant current accuracy of the second-stage circuit 104 and avoiding 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.

[0038] The adaptive two-stage control LED driver circuit of the embodiment of the present application is suitable for MR16 LED lamps and is compatible with traditional halogen lamp electronic transformer and inductive transformer input systems.

[0039] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

[0041] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present invention, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. An adaptive two-stage control LED driver circuit, characterized in that: include: a rectifier bridge, configured to rectify a voltage signal from an input source and output a first voltage signal, wherein the input source is an inductive transformer or an electronic transformer; an input detection module, configured to receive the first voltage signal and distinguish a type of the first voltage signal; A first-stage boost circuit is connected to the input detection module and is 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; When the first-stage boost circuit is started, it outputs the boosted stable voltage to the second-stage circuit to drive the LED load. 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.

2. The LED driving circuit according to claim 1, wherein: The input detection module includes a voltage divider circuit and a comparator; The voltage divider circuit includes two first resistors and a second resistor connected in series, and is used to divide the first voltage signal to generate a second voltage signal; The comparator has an inverting terminal receiving the second voltage signal, a non-inverting terminal connected to a preset threshold voltage, and an output terminal connected to an enable pin of the first-stage boost circuit; The comparator outputs a control signal according to a comparison result between the second voltage signal and the preset threshold voltage signal to control the first-stage boost circuit to start or stop.

3. The LED driving circuit according to claim 2, wherein: The comparator outputs a control signal according to a comparison result between the second voltage signal and the preset threshold voltage signal to control the first-stage boost circuit to start or shut down, 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: According to the difference in voltage signals from different input sources, the ratio of the first resistor to the second resistor is set to control the voltage division ratio.

5. The LED driving circuit according to claim 4, characterized in that: The ratio of the first resistor to the second resistor is [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 starts 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 turned off, and the second-stage circuit receives the first voltage signal through a diode to drive the LED load, thereby avoiding switching losses of the first-stage boost circuit.

8. The LED driving circuit according to claim 7, characterized in that: 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 step-up constant current circuit or a step-down constant current circuit, which is used to adjust 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 reuse some components to reduce redundant hardware configuration and lower BOM cost.

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