LED lamp pressure detection device and method

Abstract

The embodiment of the invention provides an LED lamp voltage detection device and method. The device comprises a biasing circuit, at least two groups of preprocessing circuits with consistent structures and a signal processing circuit, the preprocessing circuit comprises a signal attenuation circuit, a first MOS tube, a second MOS tube and a third MOS tube, the output end of the signal attenuation circuit is connected with the drain electrode of the first MOS tube, the grid electrodes of the first MOS tube and the second MOS tube are connected with enable signals, the source electrode of the first MOS tube is connected with a node, the grid electrode of the second MOS tube is connected with a node, the source electrode of the second MOS tube is connected with the input end of the signal processing circuit, and the output end of the signal processing circuit is connected with the output end of the signal processing circuit. The grid electrode of the third MOS tube is connected with an inversion signal of the enable signal, the drain electrode of the third MOS tube is connected with the node, and the source electrode of the third MOS tube is grounded.

Description

Technical Field

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

[0002] With the development of science and technology and the popularization of smart devices, human-computer interaction has received more and more attention from users. Light plays an important role as a carrier of information transmission. LED is particularly important in applications such as smart speaker breathing lights, car atmosphere 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, when the LED is lit, it will generate heat, causing the temperature of the LED to change. The temperature change causes the luminous flux to change when the current remains unchanged. For monochrome applications, this will affect the brightness of the LED. For mixed-color applications, the brightness of each channel will change, affecting the display effect. Therefore, different driving currents need to be used at different temperatures to maintain the same display effect. Temperature monitoring will introduce additional devices to increase manufacturing costs, so the industry usually adopts the method of detecting the voltage across the LED lamp to estimate the LED temperature. In addition, as the use time goes by, the LED lamp will age, and aging will also affect the LED lamp voltage. The aging of the lamp can be evaluated by the voltage across the LED.

[0004] Therefore, how to realize the measurement of LED lamp voltage has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, one of the technical problems solved by the embodiments of the present application is to provide a lamp voltage detection device and method for LEDs, which at least partially solve 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 comprising: a bias circuit for providing a bias current for the LED; at least two groups of pre-processing circuits with the same structure, respectively used to attenuate the lamp voltages at both ends of a selected channel 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 pre-processing circuit comprises: a signal attenuation circuit and a first MOS tube, a second MOS tube and a third MOS tube, the output end of the signal attenuation circuit is connected to the drain of the first MOS tube, the gates of the first MOS tube and the second MOS tube are both connected to an enable signal, the source of the first MOS tube is connected to a node, and the gates of the second MOS tube are connected to an enable signal. The gate is connected to node A, the source of the second MOS tube is connected to the input end of the signal processing circuit, the gate of the third MOS tube is connected to the inverted signal of the enable signal, the drain of the third MOS tube is connected to the node, and the source of the third MOS tube is grounded; the enable signal corresponding to the selected channel in the LED is high level, the first MOS tube and the second MOS tube are turned on, and the attenuated two-end lamp voltage signal 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 low level, the first MOS tube and the second MOS tube are turned off, and the node is turned on by the inverted signal of the enable signal and pulled down to the ground, so that the source voltage of the first MOS tube is 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, which is applied to the lamp voltage detection device described in the first aspect, and includes: providing a bias current for 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] The lamp voltage detection device of the embodiment of the present application is used to detect the lamp voltage at both ends of the LED through at least two sets of pre-processing circuits with the same structure, respectively, the signal attenuation circuit attenuates the lamp voltage at both ends, and the first MOS tube, the second MOS tube and the third MOS tube select the channel in the LED. The embodiment of the present application reduces the requirements for the design process and increases the portability of the circuit through the signal attenuation circuit and the circuit connection relationship of the first MOS tube, the second MOS tube and the third MOS tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Hereinafter, some specific embodiments of the present application will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings: Figure 1 This is a schematic diagram of the circuit structure of a lamp voltage detection device for an LED according to an embodiment of the present application; Figure 2 A circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED according to another embodiment of the present application; Figure 3 This is a circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED according to another embodiment of the present application; Figure 4 This is a circuit diagram of a preprocessing circuit of a lamp voltage detection device for an LED according to another embodiment of the present application; Figure 5 This is a circuit diagram of a voltage-to-current circuit of a lamp voltage detection device for an LED according to another embodiment of the present application; Figure 6 This is a circuit diagram of a gain adjustment and output circuit of a LED lamp voltage detection device according to yet another embodiment of the present application. DETAILED DESCRIPTION

[0010] 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 described clearly and in detail below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in the field based on the embodiments in the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0011] Reference is made in the following detailed description to the accompanying drawings, which form a part of the detailed description and illustrate exemplary embodiments. In addition, 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 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 limited only by the appended claims and their equivalents.

[0012] In the following description, numerous details are set forth. However, it will be apparent to those skilled in the art that the embodiments herein can be practiced without these specific details. In some cases, known methods and devices are shown in block diagram form, rather than in detail, to avoid blurring the embodiments herein. References to "embodiment" or "one embodiment" or "some embodiments" throughout this specification mean that the specific features, structures, functions or characteristics described in conjunction with the embodiment are included in at least one embodiment herein. Therefore, the phrases "in an embodiment" or "in one embodiment" or "some embodiments" appearing throughout this specification do not necessarily refer to the same embodiment. In addition, in one or more embodiments, specific features, structures, functions or characteristics may be combined in any suitable manner. For example, the first embodiment may be combined with the second embodiment in any case where the specific features, structures, functions or characteristics associated with the two embodiments are not mutually exclusive.

[0013] 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.

[0014] The terms "coupled" and "connected" together with their derivatives may be used herein to describe functional or structural relationships between components. It should be understood that these terms are not intended to be synonymous with each other. On the contrary, 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 (with other intermediate elements between them) physical or electrical contact with each other, and / or that two or more elements cooperate or interact with each other (e.g., as in a cause-and-effect relationship).

[0015] 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 relationship is noteworthy. 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 intervening materials. Also, a material disposed between two materials or materials may be in direct contact with both layers, or may have one or more intervening layers. In contrast, a first material or material "above" a second material or material is in direct contact with the second material / materials. Similar distinctions are made in the context of component assembly.

[0016] As used throughout the description herein and in the claims, a list of items connected 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.

[0017] 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," "approximately," "close to," and "approximately" generally refer to within + / - 10% of a target value.

[0018] The usual LED detection includes two parts: bias and detection. In the normal lighting stage, the LED is biased and powered by independent current sources controlled by PWM. The same constant current source is reused by a multiplexer during the LED lamp voltage detection stage. One end of the detection circuit is connected to the power supply, and the other end is connected to the cathode of each lamp through a multiplexer. All channels share a differential detection circuit, which is output through an analog-to-digital converter after the detection is completed. By sequentially detecting the anode (power supply) and cathode voltage of the LED, this solution switches the power supply and cathode to the detection circuit in turn through a switch. Since the results of the two times are not at the same time point, if there is a large fluctuation in the power supply, the measurement results will be inaccurate. At the same time, since two measurements are required for one detection cycle, this increases the test time and affects the normal working time ratio of the lamp (maximum PWM duty cycle).

[0019] In order to solve the above problems, the present application provides a lamp voltage detection device for LEDs. Figure 1 , the device comprises: The bias circuit 101 is used to provide a bias current for the LED.

[0020] 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 LED to obtain attenuated lamp voltage signals at both ends.

[0021] 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.

[0022] Specifically, in order to ensure the measurement accuracy, the embodiment of the present application will detect the LED anode (VBAT) and cathode (VLEDx) at the same time, and reuse the same set of signal processing circuits 103 when detecting different channels. The pre-processing circuit 102 selects the lamp voltage at both ends of a channel for attenuation processing to obtain the attenuated lamp voltage signal at both ends. The attenuated lamp voltage signal at both ends is sent to the signal processing circuit 103 for processing. One channel is used to detect the anode (power supply) and cathode of the lamp at the same time. Each channel can use two sets of pre-processing circuits with the same structure. 2n sets of pre-processing circuits are needed to detect n channels, and the channel selection is performed through the enable signal EN_CHx (x=1,2,…,n); or, the same pre-processing circuit is used to detect the anode (power supply) of the lamp, and n sets of pre-processing circuits with the same structure are used to detect the cathode of the lamp respectively, which requires n+1 sets of pre-processing circuits. At this time, the n sets of pre-processing circuits for detecting the cathode voltage are controlled by the enable signal EN_CHx (x=1,2,…,n), and the anode (power supply) detection is controlled by the signal after the "OR" operation of the enable signal EN_CHx (x=1,2,…,n).

[0023] It is worth noting that Figure 1 Only a lamp voltage detection device for 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. The number of preprocessing circuits 102 corresponds to the number of LEDs that need to be detected.

[0024] See also Figure 2 , the preprocessing circuit 102 of the embodiment of the present application includes: The signal attenuation circuit 1021 and the first MOS transistor DM1, the second MOS transistor M1 and the 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 the node A, the gate of the second MOS transistor M1 is connected to the 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 signal ENN_CHx of the enable signal, the drain of the third MOS transistor M2 is connected to the node A, and the source of the third MOS transistor M2 is grounded.

[0025] 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-end 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 turned on by the inverted signal ENN_CHx of the enable signal and pulled down to the ground by the third MOS transistor M2, so that the source voltage of the first MOS transistor DM1 is lower than the drain voltage.

[0026] Depending on the process selected in the specific implementation process, the first MOS tube DM1 may exhibit different characteristics. If the process selected by the first MOS tube DM1 only provides asymmetric devices, since the asymmetric devices are only unidirectional withstanding voltage, if other channels are closed when measuring a certain channel, the source voltage of the first MOS tube DM1 may be greater than the drain voltage, which will damage the first MOS tube DM1. Or the source and body terminals of the device selected by the first MOS tube DM1 are connected together, and the "back-to-back" diode between the source and the drain becomes unidirectional, resulting in the parasitic body diode being turned on 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 the embodiment of the present application, when a channel is selected, even if the enable signal EN_CHx is at a high level, the first MOS tube DM1 and the second MOS tube M1 are turned on. The attenuation voltage output by the signal attenuation circuit 1021 is output from the input terminal Vi of the circuit composed of the first MOS tube DM1, the second MOS tube M1 and the third MOS tube M2 to the output terminal Vo of the circuit composed of the first MOS tube DM1, the second MOS tube M1 and the third MOS tube M2, that is, the input terminal of the signal processing circuit 103. At this time, the enable signal EN_CHx of the remaining channels that are not selected is at a low level, the first MOS tube DM1 and the second MOS tube M1 are turned off, and the node A pulls the turned-on third MOS tube M2 down to the ground through the inverted signal ENN_CHx of the enable signal, ensuring that the potential of the node A (that is, the source level of the first MOS tube DM1) is lower than the drain, preventing the first MOS tube DM1 from being damaged. The embodiment of the present application uses the second MOS tube M1 tube under the CMOS process and controls its gate to be closed, and there is no conductive channel between the source and the drain. The embodiment of the present application reduces the demand for process devices, increases the portability of the architecture, and reduces the design cost.

[0027] In the specific implementation of the embodiment of the present application, the body ends of the second MOS tube and the third MOS tube are grounded, so that the two parasitic "back-to-back" body diodes completely isolate the input end Vi and the output end Vo of the circuit composed of the first MOS tube DM1, the second MOS tube M1 and the third MOS tube M2. The embodiment of the present application further reduces the demand for process devices, increases the portability of the architecture, and reduces the design cost. 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.

[0028] In different processes, the body and source of the high-voltage device may be connected together, resulting in the first MOS tube having only a unidirectional (drain to source) isolation effect when turned off. If the common terminal potential is 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 of the first MOS tube, and isolation is achieved by the back-to-back diodes between the source and drain of the second MOS tube M1 after being turned off.

[0029] The embodiment of the present application only measures the anode and cathode of the same lamp once, and even if there is a large fluctuation in the power supply, the accuracy of the detection result can be guaranteed, and the impact on the working cycle can be reduced while obtaining the lamp voltage at both ends. The attenuation processing of the embodiment of the present application can also be implemented using CMOS devices that are not resistant to high voltage when dealing with scenes with large lamp voltage detection, to obtain better performance.

[0030] In some specific implementations of the embodiments of the present application, the bias circuit 101 includes: The first constant current source I1 is used to supply power to the LED under the control of the pulse width modulation signal of each channel.

[0031] The second constant current source I2 is used for detecting the lamp voltage of the LED, and the first constant current source is greater than the second constant current source.

[0032] Specifically, the first constant current source I1 controls the current on and off of each channel through the switch S1, and the second constant current source I2 controls its on and off through the multiplexer S2.

[0033] The bias circuit 101 of the present application has simple circuit design elements and is easy to implement.

[0034] In some other specific implementations of the embodiments of the present application, see Figure 2 The signal attenuation circuit 1021 includes two attenuation elements with known ratios and a switch element. The switch 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 element.

[0035] Specifically, the attenuation element includes a first attenuation resistor R1 and a second attenuation resistor R2, wherein a first end of the first attenuation resistor R1 is connected to one end of the LED, a second end of the first attenuation resistor R1 is connected to a first end of the second attenuation resistor R2, and a second end of the second attenuation resistor R2 is grounded.

[0036] The switch element DM4 is connected between the second attenuation resistor R2 and the ground, and the gate voltage of the switch element DM4 is controlled by the enable signal EN_CHx, thereby controlling the opening or closing of the signal attenuation circuit 1021. Specifically, the switch element DM4 is a MOS tube.

[0037] In order to ensure the accuracy of the lamp voltage, the signal attenuation circuit 1021 in the preprocessing circuit 102 of the embodiment of the present application measures the lamp anode and cathode at the same time. The circuit input ends of at least two groups of preprocessing circuits 102 with the same structure are respectively connected to the lamp anode (VBAT) and cathode nodes (VLEDx) to be measured, respectively, and pass through two attenuation resistors R1 and R2 of known proportions and a MOS tube used as a switch. The gate voltage of the MOS tube is controlled by the enable signal EN_CHx to control the circuit to be turned on or off. According to the specific value of the lamp anode (VBAT) in the usage scenario, the switch element DM4 here can select a voltage-resistant DMOS device. 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 attenuation circuit output can be expressed as shown in Formula 1: Formula 1.

[0038] By adjusting the ratio of the two resistors, the larger voltage can be linearly attenuated in a certain ratio. In this way, when dealing with scenes with large detection lamp voltages, CMOS devices that are not resistant to high voltages can be used to implement switch elements to obtain better performance.

[0039] In some specific implementations of the embodiments of the present application, see Figure 3 The signal attenuation circuit 1021 may use a cascaded first transistor R1a and a second transistor R2a to replace the attenuation resistors R1 and R2.

[0040] In some specific implementations of the embodiments of the present application, see Figure 4 The signal attenuation circuit 1021 can connect the switch MOS tube DM4b between the first attenuation resistor R1 and the second attenuation resistor R2.

[0041] The embodiment of the present application implements the signal attenuation circuit 1021 through different attenuation methods and the positions of the switch elements, thereby achieving diversification of circuit design and allowing different circuit designs to be performed according to different application scenarios.

[0042] In some specific implementations of the embodiments of the present application, see Figure 1 , the signal processing circuit 103 comprises: The voltage-to-current circuit 1031 is used to convert the attenuated voltage signals at both ends of the lamp into relevant current signals.

[0043] The gain adjustment and output circuit 1032 is used to perform gain adjustment on the current signal and convert the gain-adjusted current signal into a voltage signal and output it to a subsequent circuit.

[0044] The embodiment of the present application realizes conversion processing of the reduced two-terminal lamp voltage signal through the voltage-to-current circuit 1031 and the gain adjustment and output circuit 1032, so as to process the input signal to a suitable range for subsequent circuits such as ADC processing.

[0045] Specifically, see Figure 5 , the voltage-to-current circuit 1031 comprises: A first operational amplifier A1, a second operational amplifier A2, a fourth MOS tube M3, a fifth MOS tube M4 and a 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 terminal and the second terminal of the first resistor RA, the positive input terminal of the first operational amplifier A1 is connected to the attenuated lamp voltage signal at one end, the negative input terminal of the second operational amplifier A2 is connected to the attenuated lamp voltage signal at the other end, the output terminal of the first operational amplifier A1 is connected to the gate of the fourth MOS tube M3, the output terminal of the second operational amplifier A2 is connected to the gate of the fifth MOS tube M4, the drain of the fourth MOS tube M3 is connected to the negative input terminal of the first operational amplifier A1, the source of the fifth MOS tube M4 is connected to the positive input terminal of the second operational amplifier A2, the attenuated lamp voltage signals at both ends are respectively superimposed on the two ends of the first resistor RA to form a current signal, and the sources of the fourth MOS tube M3 and the fifth MOS tube M4 are both grounded.

[0046] The voltage-to-current circuit 1031 first uses the "virtual short" characteristic of the operational amplifier to superimpose the proportionally attenuated power supply voltage (VBAT, lamp anode voltage) VO1 processed by the pre-processing circuit 102 and the processed LEDx voltage (lamp cathode voltage) VO2 on both ends of the resistor RA to obtain a current signal related to the voltage across the LED that is better processed relative to the voltage, which can be expressed as shown in Formula 2: Formula 2.

[0047] Specifically, see Figure 6 , the gain adjustment and output circuit 1032 comprises: The current mirror circuit 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.

[0048] The gain adjustment and output circuit also includes: The second resistor RB is connected to the output end of the current mirror circuit to convert 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.

[0049] 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 tube M5 and the seventh MOS tube M6 and the resistor RB. According to the needs, the current mirror circuit composed of the sixth MOS tube M5 and the seventh MOS tube M6 can be replaced with different architectures to meet the use requirements, and the gain size is adjusted by changing the proportional relationship between the sixth MOS tube M5 and the seventh MOS tube M6 on both sides of the current mirror, and finally converted into a voltage signal output through the second resistor RB. Similarly, by adjusting the proportional 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, so that subsequent circuits such as ADC can convert it into a digital signal. The output voltage of this gain adjustment and output circuit 1032 can be expressed by formula three as follows: Formula three.

[0050] Wherein k2 is the mirror ratio of the sixth MOS transistor M5 and the seventh MOS transistor M6.

[0051] The output VFW finally obtained by the preprocessing circuit and the signal processing circuit can be expressed by formula 4: Formula 4.

[0052] Among them: k1 is the attenuation ratio set by the attenuation circuit, k2 is the mirror ratio of the sixth MOS tube M5 and the seventh MOS tube M6, and k3 is the ratio of the resistance value of the resistor RB to that of the resistor RA.

[0053] It should be pointed out that, according to the needs of implementation, the various components / steps 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 components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present application.

[0054] Those of ordinary skill in the art will appreciate that the units and method steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present application.

[0055] The embodiments of the present application are described but not limited thereto. Ordinary technicians in the relevant technical field may 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 belong to the scope of the embodiments of the present application. The scope of patent protection of the embodiments of the present application should be defined by the claims.

Claims

1. A LED lamp voltage detection device, characterized in that: The device comprises: A bias circuit for providing a bias current for the LED; at least two sets of pre-processing circuits with the same structure for attenuating the lamp voltage at both ends of the selected channel 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 comprises: A signal attenuation circuit and a first MOS tube, a second MOS tube and a third MOS tube, wherein the output end of the signal attenuation circuit is connected to the drain of the first MOS tube, the gates of the first MOS tube and the second MOS tube are both connected to an enable signal, the source of the first MOS tube is connected to a node, the gate of the second MOS tube is connected to a node, the source of the second MOS tube is connected to the input end of the signal processing circuit, the gate of the third MOS tube is connected to an inverted signal of the enable signal, the drain of the third MOS tube is connected to the node, and the source of the third MOS tube is grounded.

2. The device according to claim 1, characterized in that The enable signal corresponding to the selected channel in the LED is at a high level, the first MOS tube and the second MOS tube are turned on, and the attenuated two-end lamp voltage signal 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 tube and the second MOS tube are turned off, the node is turned on by the inverted signal of the enable signal and the third MOS tube is pulled down to the ground, so that the source voltage of the first MOS tube is lower than the drain voltage.

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

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

5. The device according to claim 1, characterized in that The bias circuit comprises: A first constant current source, 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 perform lamp voltage detection on the LED, and 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 comprises: Two attenuation elements and a switch element with known ratios are provided. The switch element is controlled by the enable signal to turn on or off the attenuation circuit. The attenuation ratio of the lamp voltage signal is adjusted by adjusting the ratio of the attenuation element.

7. The device according to claim 6, characterized in that The attenuation element comprises a first attenuation element and a second attenuation element, wherein 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 a first end of the second attenuation element, and a second end of the second attenuation element is grounded; The switch element is connected between the first attenuation element and the second attenuation element, or the switch element is connected between the second attenuation element and ground, and the gate voltage of the switch element is controlled by the enable signal to control the on or off of the attenuation circuit; The attenuation element is an attenuation resistor or a cascade transistor, and the switch element is a switch MOS tube.

8. The device according to claim 1, characterized in that The signal processing circuit comprises: A voltage-to-current circuit, used for converting the attenuated two-end lamp voltage signal into a related current signal; The gain adjustment and output circuit is used to perform gain adjustment on the current signal and convert the gain-adjusted current signal into a voltage signal and output it to a subsequent circuit.

9. The device according to claim 8, characterized in that The voltage-to-current circuit comprises: A first operational amplifier, a second operational amplifier, a fourth MOS tube, a fifth MOS tube and a first resistor, wherein 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 lamp voltage signal at one end, the negative input terminal of the second operational amplifier is connected to the attenuated lamp voltage signal at the other end, the output terminal of the first operational amplifier is connected to the gate of the fourth MOS tube, the output terminal of the second operational amplifier is connected to the gate of the fifth MOS tube, the drain of the fourth MOS tube is connected to the negative input terminal of the first operational amplifier, the source of the fifth MOS tube is connected to the positive input terminal of the second operational amplifier, and the attenuated lamp voltage signals at both ends are respectively superimposed on the two 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 comprises: The current mirror circuit adjusts 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, characterized in that The gain adjustment and output circuit further includes: A second resistor, the second resistor is connected to the output end of the current mirror circuit, converts the gain-adjusted current signal into a voltage signal, and 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 a 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 to 11, and the method comprises: Providing a bias current to the LED; Attenuating the lamp voltage at both ends of the selected channel in the LED to obtain attenuated lamp voltage signals at both ends; The attenuated two-terminal lamp voltage signal is processed, and the processed signal is sent to a subsequent circuit.

Images