An LED lamp voltage detection device and method

Abstract

An embodiment of the present application provides an LED lamp voltage detection device and method. The device includes: a bias circuit, at least two groups of preprocessing circuits with the same structure, and a signal processing circuit; the preprocessing circuit includes: a signal attenuation circuit, a first MOS transistor, a second MOS transistor, and a third MOS transistor. The output end of the signal attenuation circuit is connected to the drain of the first MOS transistor. The gates of the first MOS transistor and the second MOS transistor are both connected to an enable signal. The source of the first MOS transistor is connected to a node. The drain of the second MOS transistor is connected to the node. The source of the second MOS transistor is connected to the input end of the signal processing circuit. The gate of the third MOS transistor is connected to the inverted signal of the enable signal. The drain of the third MOS transistor is connected to the node. The source of the third MOS transistor is grounded.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of LEDs, and in particular, to a device and method for detecting the lamp voltage of an LED. Background Art

[0002] With the development of technology and the popularization of intelligent devices, human-computer interaction has attracted more and more attention from users. As a carrier for information transmission, light plays an important role. LEDs are particularly important in applications such as the breathing lights of smart speakers, automotive ambient lights, and light language displays. Usually, LEDs are driven by a constant current source based on PWM (pulse width modulation) to achieve effects such as breathing, dimming, and color mixing.

[0003] In fact, after the LED is lit, heat is generated, which causes the temperature of the LED to change. The temperature change causes the luminous flux to change when the current remains unchanged. For monochromatic applications, this will affect the brightness of the LED at this time. For color mixing applications, since the brightness changes of each channel are different, the color of the lamp will change, affecting the display effect. Therefore, different drive currents need to be used at different temperatures to maintain the same display effect. Monitoring the temperature will introduce additional components and increase the manufacturing cost. Therefore, currently in the industry, the method of detecting the voltage across the LED lamp is usually adopted to estimate the LED temperature. In addition, as the LED lamp ages over time, the aging will also affect the lamp voltage of the LED, and the aging condition of the lamp can be evaluated through the voltage across the LED.

[0004] Therefore, how to achieve the measurement of the lamp voltage of an LED has become a technical problem to be solved urgently. Summary of the Invention

[0005] In view of this, one of the technical problems to be solved by the embodiments of the present application is to provide a device and method for detecting the lamp voltage of an LED, which at least partially solves the above technical problems.

[0006] In a first aspect, an embodiment of the present application provides a lamp voltage detection device for an LED. The device includes: a bias circuit for providing a bias current to the LED; at least two sets of preprocessing circuits with the same structure, respectively used for attenuating the lamp voltages at both ends of the selected channels in the LED to obtain attenuated lamp voltage signals at both ends; a signal processing circuit for processing the attenuated lamp voltage signals at both ends and sending the processed signals to subsequent circuits. The preprocessing circuit includes: a signal attenuation circuit, a first MOS transistor, a second MOS transistor, and a third MOS transistor. The output end of the signal attenuation circuit is connected to the drain of the first MOS transistor. The enable signals connected to the gates of the first MOS transistor and the second MOS transistor are the same enable signal. The source of the first MOS transistor is connected to a node. The drain of the second MOS transistor is connected to node A. The source of the second MOS transistor is connected to the input end of the signal processing circuit. The gate of the third MOS transistor is connected to the inverted signal of the same enable signal. The drain of the third MOS transistor is connected to the node. The source of the third MOS transistor is grounded. When the enable signal corresponding to the selected channel in the LED is at a high level, the first MOS transistor and the second MOS transistor are turned on, and the attenuated lamp voltage signal output by the signal attenuation circuit is sent to the signal processing circuit. When the enable signal corresponding to the unselected channel in the LED is at a low level, the first MOS transistor and the second MOS transistor are turned off, and the node is pulled low to the ground through the inverted signal of the enable signal to turn on the third MOS transistor, making the source voltage of the first MOS transistor lower than the drain voltage.

[0007] In a second aspect, an embodiment of the present application provides a method for detecting the lamp voltage of an LED. The method is applied to the lamp voltage detection device described in the first aspect. The method includes: providing a bias current to the LED; attenuating the lamp voltages at both ends of the selected channels in the LED to obtain attenuated lamp voltage signals at both ends; processing the attenuated lamp voltage signals at both ends and sending the processed signals to subsequent circuits.

[0008] For the lamp voltage detection device in the embodiment of the present application, the device uses at least two sets of preprocessing circuits with the same structure to respectively detect the lamp voltages at both ends of the LED. The signal attenuation circuit attenuates the lamp voltages at both ends respectively, and the first MOS transistor, the second MOS transistor, and the third MOS transistor select the channels in the LED. Through the circuit connection relationship of the signal attenuation circuit, the first MOS transistor, the second MOS transistor, and the third MOS transistor in the embodiment of the present application, the requirements for the design process are reduced, and the portability of the circuit is increased. Description of the Drawings

[0009] Some specific embodiments of the embodiments of the present application will be described in detail below with reference to the accompanying drawings in an exemplary rather than restrictive manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0010] Figure 1 is a schematic circuit diagram of a lamp voltage detection device for an LED in an embodiment of the present application;

[0011] Figure 2 is a schematic circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED in another embodiment of the present application;

[0012] Figure 3 is a schematic circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED in still another embodiment of the present application;

[0013] Figure 4 is a schematic circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED in still another embodiment of the present application;

[0014] Figure 5 is a schematic circuit diagram of a voltage-to-current circuit of a lamp voltage detection device for an LED in still another embodiment of the present application;

[0015] Figure 6 is a schematic circuit diagram of a gain adjustment and output circuit of a lamp voltage detection device for an LED in still another embodiment of the present application. Detailed Embodiments

[0016] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and detailedly described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art shall fall within the scope of protection of the embodiments of the present invention.

[0017] Reference is made to the accompanying drawings in the following detailed description, which form a part of the detailed description and illustrate exemplary embodiments. Additionally, it is to be understood that other embodiments may be utilized and structural and / or logical changes may be made without departing from the scope of the claimed subject matter. It should also be noted that directions and references (e.g., up, down, top, bottom, etc.) may be used solely for the purpose of facilitating the description of features in the drawings. Thus, the following detailed description is not to be taken in a limiting sense, and the scope of the claimed subject matter is defined only by the appended claims and their equivalents.

[0018] In the following description, numerous specific details are set forth. However, it will be apparent to those skilled in the art that embodiments herein may be practiced without these specific details. In some instances, well-known methods and devices are shown in block diagram form, rather than in detail, to avoid obscuring the embodiments herein. References throughout this specification to "an embodiment" or "one embodiment" or "some embodiments" mean that a particular feature, structure, function, or characteristic described in connection with the embodiment is included in at least one embodiment herein. Thus, the appearances of the phrases "in an embodiment" or "in one embodiment" or "some embodiments" throughout this specification are not necessarily referring to the same embodiment. Further, in one or more embodiments, the particular features, structures, functions, or characteristics may be combined in any suitable manner. For example, a first embodiment may be combined with a second embodiment in any case where the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive.

[0019] As used in the description and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0020] The terms "coupled" and "connected" along with their derivatives may be used herein to describe a functional or structural relationship between components. It should be understood that these terms are not intended as synonyms for each other. Rather, in a particular embodiment, "connected" may be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. "Coupled" may be used to indicate that two or more elements are in direct or indirect physical contact or electrical contact with each other (with other intermediate elements between them), and / or that two or more elements cooperate or interact with each other (e.g., as in a causal relationship).

[0021] As used herein, the terms "above", "below", "between", and "on" refer to the relative position of one component or material with respect to other components or materials, where such physical relationships are significant. For example, in the context of materials, a material or materials disposed above or below another material may be in direct contact, or may have one or more intermediate materials. Also, a material disposed between two materials or materials may be in direct contact with the two layers, or may have one or more intermediate layers. In contrast, a first material or materials "on" a second material or materials is in direct contact with that second material / material. Similar distinctions are to be made in the context of component assembly.

[0022] As used throughout this description and in the claims, a list of items linked by the term "at least one of" or "one or more of" may mean any combination of the listed items. For example, the phrase "at least one of A, B, or C" may mean A; B; C; A and B; A and C; B and C; or A, B, and C.

[0023] The term "circuit" or "module" may refer to one or more passive and / or active components that are arranged to cooperate with each other to provide a desired functionality. The term "signal" may refer to at least one current signal, voltage signal, or magnetic signal. The terms "substantially," "close to," "approximately," "close to," and "approximately" generally mean within + / - 10% of a target value.

[0024] Typical LED testing involves two steps: biasing and detection. During normal LED lighting, each LED is biased and powered by a separate, PWM-controlled current source. During the LED voltage detection phase, a multiplexer reuses the same constant current source. One end of the detection circuit is connected to the power supply, and the other end is connected to the cathodes of each lamp via a multiplexer. All channels share a differential detection circuit, and after detection, the output is output via an analog-to-digital converter. This solution sequentially detects the LED anode (power supply) and cathode voltages. This solution uses a switch to sequentially connect the power supply and cathode to the detection circuit. Because the two measurements are not taken at the same time, significant fluctuations in the power supply can lead to inaccurate measurements. Furthermore, since two measurements are performed per detection cycle, this increases test time and affects the percentage of time the lamp is operating normally (maximum PWM duty cycle).

[0025] In order to solve the above problems, the present invention provides a device for detecting the lamp voltage of an LED. Figure 1 , the device comprises:

[0026] The bias circuit 101 is used to provide a bias current for the LED.

[0027] At least two groups of pre-processing circuits 102 with the same structure are respectively used to attenuate the lamp voltages at both ends of the selected channels in the LEDs to obtain attenuated lamp voltage signals at both ends.

[0028] The signal processing circuit 103 is used to process the attenuated lamp voltage signal at both ends and send the processed signal to subsequent circuits.

[0029] Specifically, to ensure the measurement accuracy, in the embodiments of the present application, the anode (VBAT) and cathode (VLEDx) of the LED are detected simultaneously, and the same set of signal processing circuits 103 are multiplexed when detecting different channels. The preprocessing circuit 102 selects the two-end lamp voltages of one channel for attenuation processing to obtain the attenuated two-end lamp voltage signals. The attenuated two-end lamp voltage signals are sent to the signal processing circuit 103 for processing. When detecting one channel, the anode (power supply) and cathode of the lamp are detected simultaneously. Each channel can respectively adopt two sets of preprocessing circuits with the same structure. A total of 2n sets of preprocessing circuits are required to detect n channels, and the channel selection is performed through the enable signal EN_CHx (x = 1, 2,..., n); alternatively, the same preprocessing circuit is used to detect the anode (power supply) of the lamp, and n sets of preprocessing circuits with the same structure are respectively used to detect the cathode of the lamp, and a total of n + 1 sets of preprocessing circuits are required. At this time, the n sets of preprocessing circuits for detecting the cathode voltage are controlled by the enable signal EN_CHx (x = 1, 2,..., n), and the detection of the anode (power supply) is controlled by the signal obtained by performing an "OR" operation on the enable signal EN_CHx (x = 1, 2,..., n).

[0030] It should be noted that Figure 1 only the lamp voltage detection device of one LED is shown. If the lamp voltages of two LEDs need to be measured, two sets of preprocessing circuits 102 with the same structure are required, and the number of preprocessing circuits 102 corresponds to the number of LEDs to be detected.

[0031] See Figure 2 , the preprocessing circuit 102 in the embodiments of the present application includes:

[0032] A signal attenuation circuit 1021, a first MOS transistor DM1, a second MOS transistor M1, and a third MOS transistor M2. The output end of the signal attenuation circuit 1021 is connected to the drain of the first MOS transistor DM1. The gates of the first MOS transistor DM1 and the second MOS transistor M1 are both connected to the enable signal EN_CHx. The source of the first MOS transistor DM1 is connected to node A. The drain of the second MOS transistor M1 is connected to node A. The source of the second MOS transistor M1 is connected to the input end of the signal processing circuit. The gate of the third MOS transistor M2 is connected to the inverted enable signal ENN_CHx of the enable signal EN_CHx. The drain of the third MOS transistor M2 is connected to node A. The source of the third MOS transistor M2 is grounded.

[0033] The enable signal EN_CHx corresponding to the selected channel in the LED is at a high level, the first MOS transistor DM1 and the second MOS transistor M1 are turned on, and the attenuated two-terminal lamp voltage signal output by the signal attenuation circuit 1021 is sent to the signal processing circuit; the enable signal EN_CHx corresponding to the unselected channel in the LED is at a low level, the first MOS transistor DM1 and the second MOS transistor M1 are turned off, and the node A is pulled low to the ground by turning on the third MOS transistor M2 through the inverted enable signal ENN_CHx, making the source voltage of the first MOS transistor DM1 lower than the drain voltage.

[0034] According to different processes selected in the specific implementation process, the first MOS transistor DM1 may exhibit different characteristics. If the process selected for the first MOS transistor DM1 only provides asymmetric devices, since the asymmetric devices are only unidirectionally voltage-resistant, if other channels are turned off when measuring a certain channel, it may occur that the source voltage of the first MOS transistor DM1 is greater than the drain voltage, which will damage the first MOS transistor DM1. Or the source and body terminals of the device selected for the first MOS transistor DM1 are connected together, and the "back-to-back" diode between the source and the drain becomes unidirectional, resulting in the conduction of the parasitic body diode when the voltage difference is large, and the signal processing circuit 103 cannot correctly obtain the attenuated voltage output by the signal attenuation circuit 1021. In the embodiment of the present application, when a certain channel is selected, the enable signal EN_CHx is at a high level, and the first MOS transistor DM1 and the second MOS transistor M1 are turned on. The attenuated voltage output by the signal attenuation circuit 1021 is input from the input terminal Vi of the circuit composed of the first MOS transistor DM1, the second MOS transistor M1 and the third MOS transistor M2, and output to the output terminal Vo of the circuit composed of the first MOS transistor DM1, the second MOS transistor M1 and the third MOS transistor M2, that is, the input terminal of the signal processing circuit 103. At this time, the enable signals EN_CHx of the remaining unselected channels are at a low level, the first MOS transistor DM1 and the second MOS transistor M1 are turned off, and the node A pulls the turned-on third MOS transistor M2 to the ground through the inverted enable signal ENN_CHx, ensuring that the potential of the node A (i.e., the source of the first MOS transistor DM1) is lower than the drain, preventing the first MOS transistor DM1 from being damaged. The embodiment of the present application uses the second MOS transistor M1 under the CMOS process and controls its gate to be turned off, and there is no conductive channel between the source and the drain. The embodiment of the present application reduces the requirements for process devices, increases the portability of the architecture, and reduces the design cost.

[0035] In the specific implementation of the embodiment of the present application, the body terminals of the second MOS transistor and the third MOS transistor are grounded, so that the two parasitic "back-to-back" body diodes completely isolate the input terminal Vi and the output terminal Vo of the circuit composed of the first MOS transistor DM1, the second MOS transistor M1 and the third MOS transistor M2. The embodiment of the present application further reduces the requirements for process devices, increases the portability of the architecture, and reduces the design cost.

[0036] Specifically, the first MOS transistor DM1 is a DMOS transistor, and the second MOS transistor M1 and the third MOS transistor M2 are NMOS transistors.

[0037] In different processes, the body terminal and the source terminal of a high-voltage device may be connected together, resulting in the first MOS transistor having only a unidirectional (drain-to-source) isolation function when turned off. If the common terminal potential is relatively high, it will affect the operation of the attenuation circuit. The circuit design of the embodiment of the present application has no restrictions on the connection relationship of the body terminal of the first MOS transistor, and isolation is achieved through the back-to-back diode between the source and drain of the second MOS transistor M1 after it is turned off.

[0038] The embodiment of the present application only measures the anode and cathode of the same lamp once. Even if there are large fluctuations in the power supply, it can ensure the accuracy of the detection result. While obtaining the lamp voltage at both ends, it can reduce the impact on the duty cycle. The attenuation processing of the embodiment of the present application can also be implemented using a CMOS device that is not resistant to high voltage when dealing with a scenario where the detected lamp voltage is relatively large, obtaining better performance.

[0039] In some specific implementations of the embodiment of the present application, the bias circuit 101 includes:

[0040] A first constant current source I1 for supplying power to the LED under the control of the pulse width modulation signal of each channel.

[0041] A second constant current source I2 for detecting the lamp voltage of the LED, and the first constant current source is greater than the second constant current source.

[0042] Specifically, the first constant current source I1 controls the on / off of the current of each channel through the switch S1, and the second constant current source I2 controls its on / off through the multiplexer S2.

[0043] The circuit design elements of the bias circuit 101 of the present application are simple and easy to implement.

[0044] In some other specific implementations of the embodiment of the present application, referring to Figure 2 , the signal attenuation circuit 1021 includes two attenuation elements with known ratios and a switching element. The switching element is controlled by an enable signal to turn on or off the attenuation circuit, and the attenuation ratio of the lamp voltage signal is adjusted by adjusting the ratio of the attenuation elements.

[0045] Specifically, the attenuation elements include a first attenuation resistor R1 and a second attenuation resistor R2. The first end of the first attenuation resistor R1 is connected to one end of the LED, the second end of the first attenuation resistor R1 is connected to the first end of the second attenuation resistor R2, and the second end of the second attenuation resistor R2 is grounded.

[0046] The switching element DM4 is connected between the second attenuation resistor R2 and the ground. The gate voltage of the switching element DM4 is controlled by the enable signal EN_CHx, thereby controlling the opening or closing of the signal attenuation circuit 1021. Specifically, the switching element DM4 is a MOS transistor.

[0047] To ensure the accuracy of the lamp voltage, the signal attenuation circuit 1021 in the preprocessing circuit 102 of the present application embodiment measures both the lamp anode and cathode simultaneously. The circuit input terminals of at least two sets of preprocessing circuits 102 with the same structure are respectively connected to the lamp anode (VBAT) and cathode node (VLEDx) to be measured, and respectively pass through two attenuation resistors R1 and R2 with known ratios and a MOS transistor used as a switch. The gate voltage of the MOS transistor is controlled by the enable signal EN_CHx to control the opening or closing of the circuit. According to the specific value of the lamp anode (VBAT) in the usage scenario, the switching element DM4 here can select a DMOS device with withstand voltage. When the enable signal EN_CHx is at a low level, the preprocessing circuit 102 can be turned off to reduce power consumption without affecting the circuit function; when the enable signal EN_CHx is at a high level, the circuit works, and the input voltage is output after being attenuated by the resistor. At this time, the output of the attenuation circuit can be expressed as shown in Formula 1:

[0048] Formula 1.

[0049] By adjusting the ratio of the two resistors, a larger voltage can be linearly attenuated in a determined ratio. In this way, when dealing with scenarios where the detected lamp voltage is large, CMOS devices that cannot withstand high voltage can also be used as the switching element to obtain better performance.

[0050] In some specific implementations of the present application embodiment, referring to Figure 3 , the signal attenuation circuit 1021 can use cascaded first transistor R1a and second transistor R2a to replace the attenuation resistors R1 and R2.

[0051] In some specific implementations of the present application embodiment, referring to Figure 4 , the signal attenuation circuit 1021 can connect the switching MOS transistor DM4b between the first attenuation resistor R1 and the second attenuation resistor R2.

[0052] The present application embodiment realizes the signal attenuation circuit 1021 through different attenuation methods and the position of the switching element, achieving diversification in circuit design, and different circuit designs can be carried out according to different application scenarios.

[0053] In some specific implementations of the present application embodiment, referring to Figure 1 , the signal processing circuit 103 includes:

[0054] The voltage-to-current circuit 1031 is used to convert the attenuated two-terminal lamp voltage signal into a related current signal.

[0055] The gain adjustment and output circuit 1032 is used to adjust the gain of the current signal and convert the current signal after gain adjustment into a voltage signal for output to the subsequent circuit.

[0056] In the embodiment of the present application, the voltage-to-current circuit 1031 and the gain adjustment and output circuit 1032 are used to implement the conversion process of the reduced two-terminal lamp voltage signal, and are used to process the input signal to a suitable range for subsequent circuits such as ADC processing.

[0057] Specifically, referring to Figure 5 the voltage-to-current circuit 1031 includes:

[0058] The first operational amplifier A1, the second operational amplifier A2, the fourth MOS transistor M3, the fifth MOS transistor M4, and the first resistor RA. The negative input terminal of the first operational amplifier A1 and the positive input terminal of the second operational amplifier A2 are respectively connected to the first end and the second end of the first resistor RA. The positive input terminal of the first operational amplifier A1 is connected to the attenuated one-terminal lamp voltage signal, and the negative input terminal of the second operational amplifier A2 is connected to the attenuated other-terminal lamp voltage signal. The output terminal of the first operational amplifier A1 is connected to the gate of the fourth MOS transistor M3, and the output terminal of the second operational amplifier A2 is connected to the gate of the fifth MOS transistor M4. The drain of the fourth MOS transistor M3 is connected to the negative input terminal of the first operational amplifier A1, and the source of the fifth MOS transistor M4 is connected to the positive input terminal of the second operational amplifier A2. The attenuated two-terminal lamp voltage signals are respectively superimposed on both ends of the first resistor RA to form a current signal, and the sources and drains of the fourth MOS transistor M3 and the fifth MOS transistor M4 are both grounded.

[0059] The voltage-to-current circuit 1031 first uses the "virtual short" characteristic of the operational amplifier to superimpose the pre-processed and proportionally attenuated power supply voltage (VBAT, lamp anode voltage) VO1 and the processed LEDx voltage (lamp cathode voltage) VO2 on both ends of the resistor RA, obtaining a current signal related to the LED two-terminal voltage that is better processed in terms of relative voltage, which can be expressed as shown in Formula Two:

[0060] Formula Two.

[0061] Specifically, referring to Figure 6 the gain adjustment and output circuit 1032 includes:

[0062] A current mirror circuit that adjusts the gain by adjusting the proportional relationship between the sixth MOS transistor M5 and the seventh MOS transistor M6 included in the current mirror circuit.

[0063] The gain adjustment and output circuit further includes:

[0064] A second resistor RB, which is connected to the output terminal of the current mirror circuit, converts the current signal after gain adjustment into a voltage signal, and the ratio of the second resistor RB to the first resistor RA is used to adjust the magnitude of the gain and the common-mode level of the voltage signal.

[0065] After the voltage-to-current circuit 1031 obtains the current signal, the final output is obtained through the gain adjustment and output circuit 1032. The gain adjustment and output circuit 1032 is used to process the obtained current signal, and mainly realizes the function of gain adjustment of the current signal through the current mirror circuit composed of the sixth MOS transistor M5 and the seventh MOS transistor M6 and the resistor RB. Among them, according to the needs, the current mirror circuit composed of the sixth MOS transistor M5 and the seventh MOS transistor M6 can be replaced with different architectures to meet the usage requirements. The gain magnitude is adjusted by changing the ratio relationship between the sixth MOS transistor M5 and the seventh MOS transistor M6 on both sides of the current mirror, and finally it is converted into a voltage signal and output through the second resistor RB. Similarly, by adjusting the ratio relationship between the second resistor RB and the first resistor RA, the overall gain and the output common-mode level of the circuit can be further adjusted, which is convenient for subsequent circuits such as ADC to convert it into a digital signal. The output voltage of this gain adjustment and output circuit 1032 can be expressed by Equation 3 as:

[0066] Equation 3.

[0067] Where k2 is the mirror ratio of the sixth MOS transistor M5 and the seventh MOS transistor M6.

[0068] The finally obtained output VFW through the preprocessing circuit and the signal processing circuit can be expressed by Equation 4 as:

[0069] Equation 4.

[0070] Where: k1 is the attenuation ratio set by the attenuation circuit, k2 is the mirror ratio of the sixth MOS transistor M5 and the seventh MOS transistor M6, and k3 is the ratio of the resistance value of the resistor RB to RA.

[0071] It should be noted that according to the implementation needs, each component / step described in the embodiments of the present application can be split into more components / steps, or two or more components / steps or partial operations of the components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present application.

[0072] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the embodiments of the present application.

[0073] This description illustrates embodiments of the present application, and is not intended to limit the embodiments of the present application. Those of ordinary skill in the relevant art can also make various changes and modifications without departing from the spirit and scope of the embodiments of the present application. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present application. The scope of patent protection of the embodiments of the present application shall be defined by the claims.

Claims

1. An LED lamp voltage detection device, characterized in that, The device includes: A bias circuit for providing a bias current to the LED; at least two sets of preprocessing circuits with the same structure for attenuating the voltages at both ends of the selected channels in the LED to obtain an attenuated voltage signal at both ends; and a signal processing circuit for processing the attenuated voltage signal at both ends and sending the processed signal to a subsequent circuit; The preprocessing circuit includes: A signal attenuation circuit, a first MOS transistor, a second MOS transistor, and a third MOS transistor. The output terminal of the signal attenuation circuit is connected to the drain of the first MOS transistor. The enable signals connected to the gates of the first MOS transistor and the second MOS transistor are the same enable signal. The source of the first MOS transistor is connected to a node. The drain of the second MOS transistor is connected to the node. The source of the second MOS transistor is connected to the input terminal of the signal processing circuit. The gate of the third MOS transistor is connected to the inverted signal of the same enable signal. The drain of the third MOS transistor is connected to the node. The source of the third MOS transistor is grounded.

2. The device according to claim 1, wherein The enable signal corresponding to the selected channel in the LED is at a high level, the first MOS transistor and the second MOS transistor are turned on, and the attenuated voltage signal at both ends output by the signal attenuation circuit is sent to the signal processing circuit; the enable signal corresponding to the unselected channel in the LED is at a low level, the first MOS transistor and the second MOS transistor are turned off, and the node is pulled low to the ground by turning on the third MOS transistor through the inverted signal of the enable signal, making the source voltage of the first MOS transistor lower than the drain voltage.

3. The device according to claim 2, characterized in that, The body terminals of the second MOS transistor and the third MOS transistor are grounded.

4. The device according to claim 3, characterized in that, The first MOS transistor is a DMOS transistor, and the second MOS transistor and the third MOS transistor are NMOS transistors.

5. The device according to claim 1, characterized in that, The bias circuit includes: A first constant current source for supplying power to the LED under the control of the pulse width modulation signal of each channel; A second constant current source for detecting the voltage of the LED. The first constant current source is greater than the second constant current source.

6. The device according to claim 1, characterized in that, The signal attenuation circuit includes: Two attenuation elements with known ratios and a switching element. The switching element is controlled by the enable signal to turn on or off the attenuation circuit. By adjusting the ratio of the attenuation elements, the attenuation ratio of the voltage signal is adjusted.

7. The device according to claim 6, characterized in that, The attenuation elements include a first attenuation element and a second attenuation element. The first end of the first attenuation element is connected to one end of the LED. The second end of the first attenuation element is connected to the first end of the second attenuation element. The second end of the second attenuation element is grounded; The switching element is connected between the first attenuation element and the second attenuation element, or the switching element is connected between the second attenuation element and the ground. The gate voltage of the switching element is controlled by the enable signal to control the turn-on or off of the attenuation circuit; The attenuation elements are attenuation resistors or cascaded transistors, and the switching element is a switching MOS transistor.

8. The device according to claim 1, wherein The signal processing circuit includes: A voltage-to-current circuit for converting the attenuated two-terminal lamp voltage signal into a related current signal; A gain adjustment and output circuit for adjusting the gain of the current signal and converting the current signal with adjusted gain into a voltage signal for output to a subsequent circuit.

9. The device according to claim 8, wherein The voltage-to-current circuit includes: A first operational amplifier, a second operational amplifier, a fourth MOS transistor, a fifth MOS transistor, and a first resistor. The negative input terminal of the first operational amplifier and the positive input terminal of the second operational amplifier are respectively connected to the first end and the second end of the first resistor. The positive input terminal of the first operational amplifier is connected to the attenuated one-terminal lamp voltage signal. The negative input terminal of the second operational amplifier is connected to the attenuated other-terminal lamp voltage signal. The output terminal of the first operational amplifier is connected to the gate of the fourth MOS transistor. The output terminal of the second operational amplifier is connected to the gate of the fifth MOS transistor. The drain of the fourth MOS transistor is connected to the negative input terminal of the first operational amplifier. The source of the fifth MOS transistor is connected to the positive input terminal of the second operational amplifier. The attenuated two-terminal lamp voltage signals are respectively superimposed on both ends of the first resistor to form the current signal.

10. The device according to claim 9, characterized in that, The gain adjustment and output circuit includes: A current mirror circuit for adjusting the gain by adjusting the proportional relationship between the seventh MOS transistor and the eighth MOS transistor included in the current mirror circuit.

11. The device according to claim 10, wherein, The gain adjustment and output circuit further includes: A second resistor connected to the output terminal of the current mirror circuit for converting the current signal with adjusted gain into a voltage signal. The ratio of the second resistor to the first resistor is used to adjust the gain and the common-mode level of the voltage signal.

12. A method for detecting the lamp voltage of an LED, characterized in that, The method is applied to the lamp voltage detection device according to any one of claims 1-11, and the method includes: Providing a bias current for the LED; Attenuating the two-terminal lamp voltage of the selected channel in the LED to obtain an attenuated two-terminal lamp voltage signal; Processing the attenuated two-terminal lamp voltage signal and sending the processed signal to a subsequent circuit.

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