LED lamp voltage measurement apparatus and method

Abstract

Provided in the embodiments of the present application are an LED lamp voltage measurement apparatus and method. The apparatus comprises: a bias circuit, at least two preprocessing circuits having an identical structure, and a signal processing circuit. Each preprocessing circuit comprises: a signal attenuation circuit, a first MOS transistor, a second MOS transistor and a third MOS transistor, wherein an output end of the signal attenuation circuit is connected to a drain electrode of the first MOS transistor, gate electrodes of the first MOS transistor and the second MOS transistor are both connected to an enable signal, a source electrode of the first MOS transistor is connected to a node, a drain electrode of the second MOS transistor is connected to the node, a source electrode of the second MOS transistor is connected to an input end of the signal processing circuit, a gate electrode of the third MOS transistor is connected to an inverted signal of the enable signal, a drain electrode of the third MOS transistor is connected to the node, and a source electrode of the third MOS transistor is grounded.

Description

An LED lamp pressure detection device and method Technical Field

[0001] This application relates to the field of LED technology, and in particular to an LED lamp pressure detection device and method. Background Technology

[0002] With the development of technology and the popularization of smart devices, human-computer interaction is receiving increasing attention from users. Light, as a carrier of information, plays an important role, and LEDs are particularly important in applications such as breathing lights in smart speakers, ambient lighting in cars, and light signal displays. LEDs are typically driven using a constant current source based on PWM (Pulse Width Modulation) to achieve effects such as breathing, dimming, and color mixing.

[0003] In reality, LEDs generate heat when lit, causing temperature variations. These temperature changes alter the luminous flux while maintaining a constant current. For monochrome applications, this affects LED brightness; for multi-color applications, the varying brightness across channels leads to color changes, impacting display quality. Therefore, different drive currents are needed at different temperatures to maintain consistent display performance. Temperature monitoring introduces additional components, increasing manufacturing costs. Currently, the industry typically estimates LED temperature by measuring the voltage across the LED terminals. Furthermore, LEDs age over time, which also affects the LED voltage. The aging status of the LED can be assessed by measuring the voltage across its terminals.

[0004] Therefore, how to measure the lamp pressure of LEDs has become a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, one of the technical problems solved by the embodiments of this application is to provide an LED lamp pressure detection device and method, which at least partially solves the above-mentioned technical problems.

[0006] In a first aspect, embodiments of this application provide an LED lamp voltage detection device, the device comprising: a bias circuit for providing a bias current to the LED; at least two sets of preprocessing circuits with identical structures, respectively used to attenuate the lamp voltage at both ends of a selected channel in the LED to obtain attenuated lamp voltage signals at both ends; and 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 comprises: a signal attenuation circuit and a first MOSFET, a second MOSFET, and a third MOSFET, the output terminal of the signal attenuation circuit being connected to the drain of the first MOSFET, the gates of the first MOSFET and the second MOSFET being connected to the same enable signal, the source of the first MOSFET being connected to a node, and the second MOSFET being connected to a node. The drain of the S-MOSFET is connected to node A, the source of the second MOSFET is connected to the input terminal of the signal processing circuit, the gate of the third MOSFET is connected to the inverted signal of the same enable signal, the drain of the third MOSFET is connected to the node, and the source of the third MOSFET is grounded. When the enable signal corresponding to the selected channel in the LED is high, the first MOSFET and the second MOSFET are turned on, and the attenuated lamp voltage signal at both ends of the output of the signal attenuation circuit is sent to the signal processing circuit. When the enable signal corresponding to the unselected channel in the LED is low, the first MOSFET and the second MOSFET are turned off, and the node turns on the third MOSFET by the inverted signal of the enable signal, pulling it low to ground, so that the source voltage of the first MOSFET is lower than the drain voltage.

[0007] Secondly, embodiments of this application provide a lamp voltage detection method for an LED, the method being applied to the lamp voltage detection device described in the first aspect, the method comprising: providing a bias current to the LED; attenuating the lamp voltage at both ends of a selected channel 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] This application's embodiment of the lamp voltage detection device uses at least two sets of identical preprocessing circuits to detect the lamp voltage at both ends of an LED. A signal attenuation circuit attenuates the lamp voltage at both ends, and a first MOSFET, a second MOSFET, and a third MOSFET select the channel within the LED. This application's embodiment, through the signal attenuation circuit and the circuit connections of the first, second, and third MOSFETs, reduces the requirements for design processes and increases the circuit's portability. Attached Figure Description

[0009] The following sections will describe some specific embodiments of the present application in a detailed manner, by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. 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 diagram of the circuit structure of an LED lamp pressure detection device according to an embodiment of this application;

[0011] Figure 2 is a circuit diagram of the preprocessing circuit of an LED lamp pressure detection device according to another embodiment of this application;

[0012] Figure 3 is a circuit diagram of the preprocessing circuit of an LED lamp pressure detection device according to another embodiment of this application;

[0013] Figure 4 is a circuit diagram of the preprocessing circuit of an LED lamp pressure detection device according to another embodiment of this application;

[0014] Figure 5 is a circuit diagram of a voltage-to-current conversion circuit of an LED lamp pressure detection device according to another embodiment of this application;

[0015] Figure 6 is a circuit diagram of the gain adjustment and output circuit of an LED lamp pressure detection device according to another embodiment of this application. Detailed Implementation

[0016] 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 thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0017] Reference is made to the accompanying drawings, which form part of the detailed description and illustrate exemplary embodiments. Furthermore, it should 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 orientations and references (e.g., up, down, top, bottom, etc.) may be used merely to facilitate the description of features in the drawings. Therefore, the following detailed description is not to be construed in a limiting sense, and the scope of the claimed subject matter is defined only by the appended claims and their equivalents.

[0018] Numerous details are set forth in the following description. However, it will be apparent to those skilled in the art that the embodiments described herein can be practiced without these specific details. In some instances, well-known methods and apparatus are shown in block diagram form rather than in detail to avoid obscuring the embodiments described herein. Throughout this specification, references to “embodiment,” “one embodiment,” or “some embodiments” mean that a particular feature, structure, function, or characteristic described in connection with that embodiment is included in at least one embodiment herein. Therefore, the phrases “in an embodiment,” “in one embodiment,” or “some embodiments” appearing throughout this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, particular features, structures, functions, or characteristics can be combined in any suitable manner. For example, a first embodiment can be combined with a second embodiment in any way that does not mutually exclude particular features, structures, functions, or characteristics associated with two embodiments.

[0019] As used in the description and appended claims, the singular forms “a (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 includes any and all possible combinations of one or more of the associated listed items.

[0020] The terms “coupling” and “connection”, along with their derivatives, are used herein to describe functional or structural relationships between components. It should be understood that these terms are not intended to be synonyms for each other. Rather, in certain embodiments, “connection” can be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. “Coupling” can be used to indicate that two or more elements are in direct or indirect physical or electrical contact with each other (with other intermediary 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 a component or material with respect to other components or materials, where such physical relationships are noteworthy. For example, in the context of materials, a material positioned above or below another material may be in direct contact with it, or may have one or more intermediate materials. Furthermore, a material positioned between two materials may be in direct contact with both layers, or may have one or more intermediate layers. In contrast, a first material or material “on” a second material or material is in direct contact with that second material / material. Similar distinctions are made in the context of component assembly.

[0022] As described throughout this document and in the claims, a list of items connected by the terms “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 terms “circuit” or “module” can refer to one or more passive and / or active components arranged to cooperate with each other to provide a desired function. The term “signal” can refer to at least one current signal, voltage signal, or magnetic signal. The terms “substantially,” “close to,” “approximately,” “near,” and “about” generally refer to within + / -10% of the target value.

[0024] Typical LED testing consists of two parts: biasing and detection. During normal lighting, LEDs are biased and powered by independent PWM-controlled current sources. The LED voltage detection stage uses a multiplexer to multiplex 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 LED via the multiplexer. All channels share a differential detection circuit, and the output is sent via an analog-to-digital converter after detection. This scheme sequentially detects the voltage at the LED anode (power supply) and the LED cathode, switching the power supply and cathode sequentially to the detection circuit. Since the two results are not at the same time, significant fluctuations in the power supply can lead to inaccurate measurements. Furthermore, since two measurements are required per detection cycle, this increases the testing time and affects the percentage of normal operating time (maximum PWM duty cycle).

[0025] To address the aforementioned problems, this application provides an LED lamp pressure detection device, as shown in Figure 1. The device includes:

[0026] Bias circuit 101 is used to provide bias current to the LED.

[0027] At least two sets of preprocessing circuits 102 with identical structures are used to attenuate the lamp voltage at both ends of the selected channel in the LED to obtain the attenuated lamp voltage signals at both ends.

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

[0029] Specifically, to ensure measurement accuracy, this embodiment of the application simultaneously detects the LED anode (VBAT) and cathode (VLEDx), and reuses the same signal processing circuit 103 when detecting different channels. The preprocessing circuit 102 selects the lamp voltage at both ends of a channel for attenuation processing to obtain the attenuated lamp voltage signals at both ends. The attenuated lamp voltage signals at both ends are sent to the signal processing circuit 103 for processing. The detection method can simultaneously detect the anode (power supply) and cathode of a lamp in a single channel. Each channel can use two sets of preprocessing circuits with identical structures. Detecting n channels requires a total of 2n sets of preprocessing circuits, and the channel selection is performed by the enable signal EN_CHx (x = 1, 2, ..., n). Alternatively, the same preprocessing circuit can be used to detect the anode (power supply) of the lamp, while n sets of preprocessing circuits with identical structures can be used to detect the cathode of the lamp, requiring a total of n+1 sets of preprocessing circuits. In this case, 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 is worth noting that Figure 1 only shows the lamp pressure detection device for one LED. If it is necessary to measure the lamp pressure of two LEDs, two sets of preprocessing circuits 102 with identical structures are required. The number of preprocessing circuits 102 corresponds to the number of LEDs to be detected.

[0031] Referring to Figure 2, the preprocessing circuit 102 of this embodiment includes:

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

[0033] When the enable signal EN_CHx corresponding to the selected channel in the LED is high, the first MOSFET DM1 and the second MOSFET M1 are turned on, and the attenuated lamp voltage signal at both ends of the output of the signal attenuation circuit 1021 is sent to the signal processing circuit. When the enable signal EN_CHx corresponding to the unselected channel in the LED is low, the first MOSFET DM1 and the second MOSFET M1 are turned off, and node A turns on the third MOSFET M2 to ground through the inverted signal ENN_CHx of the enable signal, so that the source voltage of the first MOSFET DM1 is lower than the drain voltage.

[0034] Depending on the specific process chosen, the first MOSFET DM1 may exhibit different characteristics. If the process chosen for the first MOSFET DM1 only provides asymmetric devices, since asymmetric devices only have unidirectional withstand voltage, if other channels are turned off while measuring one channel, the source voltage of the first MOSFET DM1 may be greater than the drain voltage, which could damage the first MOSFET DM1. Alternatively, if the source and body terminals of the device chosen for the first MOSFET DM1 are connected together, the "back-to-back" diode between the source and drain becomes unidirectional, causing the parasitic body diode to conduct when the voltage difference is large, and the signal processing circuit 103 cannot correctly obtain the attenuation voltage output by the signal attenuation circuit 1021. In this embodiment, when a channel is selected, even if the enable signal EN_CHx is high, the first MOSFET DM1 and the second MOSFET M1 are turned on. The attenuation voltage output by the signal attenuation circuit 1021 is from the input terminal Vi of the circuit composed of the first MOSFET DM1, the second MOSFET M1, and the third MOSFET M2 to the output terminal Vo of the same circuit, which is also the input terminal of the signal processing circuit 103. At this time, the enable signal EN_CHx for the unselected channels is low, the first MOSFET DM1 and the second MOSFET M1 are turned off, and node A pulls the conducting third MOSFET M2 to ground through the inverted signal ENN_CHx of the enable signal, ensuring that the potential of node A (i.e., the source of the first MOSFET DM1) is lower than the drain, preventing damage to the first MOSFET DM1. This embodiment uses the second MOSFET M1 in CMOS technology and controls its gate to be turned off; there is no conductive channel between the source and drain. This embodiment reduces the requirements for process devices, increases the portability of the architecture, and reduces design costs.

[0035] In a specific implementation of this application, the body terminals of the second MOSFET and the third MOSFET are grounded, allowing the two parasitic "back-to-back" body diodes to completely isolate the input terminal Vi and the output terminal Vo of the circuit composed of the first MOSFET DM1, the second MOSFET M1, and the third MOSFET M2. This application further reduces the requirements for process devices, increases the portability of the architecture, and reduces design costs.

[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 manufacturing processes, the body and source terminals of high-voltage devices may be connected together, resulting in the first MOSFET only having unidirectional (drain-to-source) isolation when turned off. If the common terminal potential is high, it will affect the operation of the attenuation circuit. The circuit design using the embodiments of this application does not restrict the connection relationship of the body terminal of the first MOSFET. Isolation is achieved by using back-to-back diodes between the source and drain of the second MOSFET M1 after turn-off.

[0038] This application embodiment performs only one measurement on the anode and cathode of the same lamp. Even with significant fluctuations in the power supply, the accuracy of the detection results can be guaranteed. While obtaining the lamp voltage at both ends, the impact on the duty cycle can be reduced. The attenuation processing in this application embodiment can also be implemented using CMOS devices that are not resistant to high voltage when dealing with scenarios with high lamp voltage, achieving better performance.

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

[0040] The first constant current source I1 is used to power the LED under the control of the pulse width modulation signal of each channel.

[0041] The second constant current source I2 is used to detect the lamp voltage of the LED. The first constant current source is greater than the second constant current source.

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

[0043] The bias circuit 101 of this application has simple circuit design components and is easy to implement.

[0044] In some other specific implementations of the embodiments of this application, referring to FIG2, the signal attenuation circuit 1021 includes two attenuation elements with known ratios and a switching element. The attenuation circuit is turned on or off by controlling the switching element with an enable signal, and the attenuation ratio of the lamp pressure signal is adjusted by adjusting the ratio of the attenuation elements.

[0045] Specifically, the attenuation element includes 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 ground. The gate voltage of the switching element DM4 is controlled by the enable signal EN_CHx, thereby controlling the signal attenuation circuit 1021 to turn on or off. Specifically, the switching element DM4 is a MOSFET.

[0047] To ensure the accuracy of the lamp voltage, the signal attenuation circuit 1021 in the preprocessing circuit 102 of this embodiment simultaneously measures both the lamp anode and cathode. The circuit input terminals of at least two identical preprocessing circuits 102 are respectively connected to the lamp anode (VBAT) and cathode nodes (VLEDx) to be measured. They pass through two attenuation resistors R1 and R2 with known ratios and a MOSFET used as a switch. The gate voltage of the MOSFET is controlled by the enable signal EN_CHx, thereby controlling the circuit to turn on or off. Depending on the specific value of the lamp anode (VBAT) in the application scenario, the switching element DM4 can be a voltage-resistant DMOS device. When the enable signal EN_CHx is low, the preprocessing circuit 102 can be turned off to reduce power consumption without affecting the circuit function. When the enable signal EN_CHx is high, the circuit operates, and the input voltage is attenuated by the resistors before being output. The output of the attenuation circuit can then be expressed as shown in Formula 1:

[0048] By adjusting the ratio of the two resistors, a larger voltage can be linearly attenuated in a defined proportion. This allows for the use of CMOS devices, which are not resistant to high voltage, to implement switching elements in scenarios with high lamp voltage, achieving better performance.

[0049] In some specific implementations of the embodiments of this application, referring to FIG3, the signal attenuation circuit 1021 can replace the attenuation resistors R1 and R2 with cascaded first transistor R1a and second transistor R2a.

[0050] In some specific implementations of this application, referring to Figure 4, the signal attenuation circuit 1021 can connect the switching MOSFET DM4b between the first attenuation resistor R1 and the second attenuation resistor R2.

[0051] The embodiments of this application implement the signal attenuation circuit 1021 by different attenuation methods and the location of the switching element, realizing the diversification of circuit design, and different circuit designs can be made according to different application scenarios.

[0052] In some specific implementations of the embodiments of this application, referring to FIG1, the signal processing circuit 103 includes:

[0053] The voltage-to-current circuit 1031 is used to convert the attenuated lamp voltage signal at both ends into a relevant current signal.

[0054] The gain adjustment and output circuit 1032 is used to adjust the gain of the current signal and convert the gain-adjusted current signal into a voltage signal for output to subsequent circuits.

[0055] This application embodiment uses a voltage-to-current circuit 1031 and a gain adjustment and output circuit 1032 to convert and process the reduced lamp voltage signals at both ends, so as to process the input signal to a suitable range for subsequent circuits such as ADC processing.

[0056] Specifically, referring to Figure 5, the voltage-to-current circuit 1031 includes:

[0057] The system consists of a first operational amplifier A1, a second operational amplifier A2, a fourth MOSFET M3, a fifth MOSFET M4, and a first resistor RA. The negative input of the first operational amplifier A1 and the positive input of the second operational amplifier A2 are connected to the first and second terminals of the first resistor RA, respectively. The positive input of the first operational amplifier A1 is connected to one attenuated lamp voltage signal, and the negative input of the second operational amplifier A2 is connected to the other attenuated lamp voltage signal. The output of the first operational amplifier A1 is connected to the gate of the fourth MOSFET M3, and the output of the second operational amplifier A2 is connected to the gate of the fifth MOSFET M4. The drain of the fourth MOSFET M3 is connected to the negative input of the first operational amplifier A1, and the source of the fifth MOSFET M4 is connected to the positive input of the second operational amplifier A2. The attenuated lamp voltage signals are superimposed across the first resistor RA to form a current signal. The drains and sources of the fourth MOSFET M3 and the fifth MOSFET M4 are both grounded.

[0058] The voltage-to-current circuit 1031 first utilizes the "virtual short" characteristic of the operational amplifier to superimpose the proportionally attenuated power supply voltage (VBAT, lamp anode voltage) VO1, processed by the preprocessing circuit 102, and the processed LEDx voltage (lamp cathode voltage) VO2 across the resistor RA, obtaining a current signal related to the voltage across the LED that is better handled by the voltage, which can be expressed as shown in Formula 2:

[0059] Specifically, referring to Figure 6, the gain adjustment and output circuit 1032 includes:

[0060] The gain of the current mirror circuit is adjusted by changing the ratio of the sixth MOSFET M5 and the seventh MOSFET M6 included in the current mirror circuit.

[0061] The gain adjustment and output circuit also includes:

[0062] The second resistor RB is connected to the output of the current mirror circuit and converts the gain-adjusted current signal into a voltage signal. The ratio of the second resistor RB to the first resistor RA is used to adjust the gain and the common-mode level of the voltage signal.

[0063] After the voltage-to-current circuit 1031 receives the current signal, the final output is obtained through the gain adjustment and output circuit 1032. The gain adjustment and output circuit 1032 processes the received current signal, primarily using a current mirror circuit composed of the sixth MOSFET M5 and the seventh MOSFET M6, and resistor RB to adjust the gain of the current signal. The current mirror circuit composed of the sixth MOSFET M5 and the seventh MOSFET M6 can be replaced with different architectures to meet specific requirements. The gain is adjusted by changing the ratio of the sixth MOSFET M5 and the seventh MOSFET M6 on both sides of the current mirror. Finally, the signal is converted into a voltage signal output through the second resistor RB. Similarly, adjusting the ratio of the second resistor RB to the first resistor RA can further adjust the overall gain and the common-mode level of the circuit output, facilitating subsequent circuits such as an ADC to convert it into a digital signal. The output voltage of this gain adjustment and output circuit 1032 can be expressed by formula three: V FW =k2·I sen ·R B Formula 3.

[0064] Where k2 is the mirror ratio of the sixth MOSFET M5 and the seventh MOSFET M6.

[0065] The final output VFW obtained through the preprocessing circuit and signal processing circuit can be expressed by Formula 4:

[0066] Where: k1 is the attenuation ratio set by the attenuation circuit, k2 is the mirror ratio of the sixth MOSFET M5 and the seventh MOSFET M6, and k3 is the ratio of the resistance values ​​of resistor RB to RA.

[0067] It should be noted that, depending on the implementation needs, the various components / steps described in the embodiments of this application can be broken down into more components / steps, or two or more components / steps or parts of the operation of components / steps can be combined into new components / steps to achieve the purpose of the embodiments of this application.

[0068] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this application.

[0069] This application describes embodiments, but is not intended to limit them. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments. Therefore, all equivalent technical solutions also fall within the scope of the embodiments. The patent protection scope of the embodiments should be defined by the claims.

Claims

1. A lamp pressure detection device for LEDs, characterized in that, The device includes: A bias circuit is used to provide bias current to the LED; at least two sets of preprocessing circuits with identical structures are used to attenuate the lamp voltage at both ends of the selected channel in the LED to obtain the attenuated lamp voltage signal at both ends; a signal processing circuit is used to process the attenuated lamp voltage signal at both ends and send the processed signal to the subsequent circuit. The preprocessing circuit includes: The signal attenuation circuit includes a first MOSFET, a second MOSFET, and a third MOSFET. The output of the signal attenuation circuit is connected to the drain of the first MOSFET. The gates of the first MOSFET and the second MOSFET are connected to the same enable signal. The source of the first MOSFET is connected to a node, the drain of the second MOSFET is connected to a node, the source of the second MOSFET is connected to the input of the signal processing circuit, the gate of the third MOSFET is connected to the inverted signal of the same enable signal, the drain of the third MOSFET is connected to the node, and the source of the third MOSFET is grounded.

2. The apparatus according to claim 1, characterized in that, When the enable signal corresponding to the selected channel in the LED is high, the first MOSFET and the second MOSFET are turned on, and the attenuated lamp voltage signal at both ends of the signal attenuation circuit is sent to the signal processing circuit; when the enable signal corresponding to the unselected channel in the LED is low, the first MOSFET and the second MOSFET are turned off, and the node turns on the third MOSFET to ground through the inverted signal of the enable signal, so that the source voltage of the first MOSFET is lower than the drain voltage.

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

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

5. The apparatus according to claim 1, characterized in that, The bias circuit includes: The first constant current source is used to power the LED under the control of the pulse width modulation signal of each channel; The second constant current source is used to detect the lamp voltage of the LED, and the first constant current source is greater than the second constant current source.

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

7. The apparatus according to claim 6, characterized in that, The attenuation element includes a first attenuation element and a second attenuation element. A first end of the first attenuation element is connected to one end of the LED, a second end of the first attenuation element is connected to the first end of the second attenuation element, and a 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 ground. The gate voltage of the switching element is controlled by the enable signal, thereby controlling the opening or closing of the attenuation circuit. The attenuation element is an attenuation resistor or a cascaded transistor, and the switching element is a switching MOS transistor.

8. The apparatus according to claim 1, characterized in that, The signal processing circuit includes: A voltage-to-current circuit is used to convert the attenuated lamp voltage signals at both ends into relevant current signals; The gain adjustment and output circuit is used to adjust the gain of the current signal and convert the gain-adjusted current signal into a voltage signal for output to subsequent circuits.

9. The apparatus according to claim 8, characterized in that, The voltage-to-current conversion circuit includes: The system comprises a first operational amplifier, a second operational amplifier, a fourth MOSFET, a fifth MOSFET, 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 and second terminals of the first resistor. The positive input terminal of the first operational amplifier is connected to one attenuated lamp voltage signal, and the negative input terminal of the second operational amplifier is connected to the other attenuated lamp voltage signal. The output terminal of the first operational amplifier is connected to the gate of the fourth MOSFET, and the output terminal of the second operational amplifier is connected to the gate of the fifth MOSFET. The drain of the fourth MOSFET is connected to the negative input terminal of the first operational amplifier, and the source of the fifth MOSFET is connected to the positive input terminal of the second operational amplifier. The attenuated lamp voltage signals are superimposed on both ends of the first resistor to form the current signal.

10. The apparatus according to claim 9, characterized in that, The gain adjustment and output circuit includes: The gain of the current mirror circuit is adjusted by changing the ratio of the seventh MOSFET and the eighth MOSFET included in the current mirror circuit.

11. The apparatus according to claim 10, characterized in that, The gain adjustment and output circuit also includes: The second resistor is connected to the output terminal of the current mirror circuit and converts the gain-adjusted current signal 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 pressure of an LED, characterized in that, The method is applied to the lamp pressure detection device according to any one of claims 1-11, and the method includes: Provide bias current to the LED; The lamp voltage at both ends of the selected channel in the LED is attenuated to obtain the attenuated lamp voltage signals at both ends; The attenuated lamp voltage signals at both ends are processed, and the processed signals are sent to subsequent circuits.

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