LED open circuit and short circuit detection circuit

Abstract

The utility model provides an LED open circuit and short circuit detection circuit comprising an LED lamp group which comprises a first LED branch circuit, a second LED branch circuit and a third LED branch circuit; the first output end of the microcontroller outputs a first control signal, the second output end of the microcontroller outputs a second control signal, the third output end of the microcontroller outputs a third control signal, and the voltage sampling end of the microcontroller is used for sampling voltage; the LED control circuit comprises a driving control circuit and a voltage sampling circuit, and the voltage sampling circuit is used for connecting the positive electrodes of the branches of the LED lamp set to the voltage sampling end of the microcontroller one by one, so that the microcontroller can sample the voltage of any one of the positive electrodes of the branches of the LED lamp set one by one through the voltage sampling end. Compared with the prior art, the open-circuit and short-circuit fault detection function of three paths of LEDs can be realized by only one path of voltage sampling, so that the occupied area of a PCB (Printed Circuit Board) is smaller, the miniaturization design of a product is facilitated, and the cost is better.

Description

[Technical Field]

[0001] This utility model relates to the field of circuit design technology, and in particular to an open / short circuit detection circuit for LEDs. [Background Technology]

[0002] For automotive RGB (i.e., three primary color LED) driver power supplies, open circuit or short circuit problems may be encountered in applications. An open circuit means that there is no current driving in the circuit, which may cause the device to malfunction. A short circuit may cause excessive current, thereby damaging the device or causing safety hazards.

[0003] As the requirements for ambient lighting in vehicles increase, the demand for high-brightness RGB lighting also increases. The current of the products is increasing while the size requirement is decreasing, resulting in a gradual increase in heat generation. This necessitates that the products be able to self-detect the fault status of the RGB flow control device, such as open circuit or short circuit, to ensure that the failure of the products will not affect the functions of the entire vehicle.

[0004] RGB has three LED branches, and each branch needs to be tested for open and short circuits. The solution requires the I / O ports (i.e., input and output ports) of multiple ADCs (analog to digital converters) to collect the RGB port voltage to determine open and short circuits. This method increases the demand for GPIO (general purpose input / output interface) resources of the MCU (Microcontroller Unit), increases the chip package size, and also requires a larger PCB (Printed Circuit Board) area, and the cost is also relatively high.

[0005] The existing technical solutions have the following problems:

[0006] 1) The above solution requires the control chip IC to have multiple ADC acquisition ports;

[0007] 2) The above solution requires a large PCB area, which cannot meet the customer's installation size requirements;

[0008] 3) The above solutions are relatively more expensive.

[0009] Therefore, it is necessary to propose a new technical solution to address the above problems. [Utility Model Content]

[0010] One of the purposes of this utility model is to provide an open and short circuit detection circuit for LEDs, which can realize the open and short circuit fault detection function of 3 LEDs with only one voltage sampling. This not only reduces the PCB area occupied and facilitates product miniaturization design, but also makes the cost more favorable.

[0011] According to one aspect of this utility model, this utility model provides an open / short circuit detection circuit for LEDs, comprising: an LED lamp group including a first LED branch, a second LED branch, and a third LED branch; a microcontroller, whose first output terminal outputs a first control signal LED0, its second output terminal outputs a second control signal LED1, its third output terminal outputs a third control signal LED2, and its voltage sampling terminal ADC_OS is used to sample voltage; an LED control circuit including a drive control circuit and a voltage sampling circuit, wherein the drive control circuit includes switching transistors Q1, Q2, and Q3, the first connection terminal of the switching transistor Q1 is connected to the power supply terminal Vdcdc, its control terminal is connected to the first output terminal of the microcontroller, its second connection terminal is connected to the positive terminal of the first LED branch, and the negative terminal of the first LED branch is grounded; the switching transistor Q2... The first connection terminal is connected to the power supply terminal Vdcdc, its control terminal is connected to the second output terminal of the microcontroller, its second connection terminal is connected to the positive terminal of the second LED branch, and the negative terminal of the second LED branch is grounded; the first connection terminal of the switching transistor Q3 is connected to the power supply terminal Vdcdc, its control terminal is connected to the third output terminal of the microcontroller, its second connection terminal is connected to the positive terminal of the third LED branch, and the negative terminal of the third LED branch is grounded; the voltage sampling circuit is used to connect the positive terminals of the first LED branch, the second LED branch, and the third LED branch one by one to the voltage sampling terminal ADC_OS of the microcontroller, so that the microcontroller can sample the voltage of any one of the positive terminals of the first LED branch, the second LED branch, and the third LED branch through the voltage sampling terminal ADC_OS.

[0012] Compared with existing technologies, this invention only requires one voltage sampling channel to realize the open circuit and short circuit fault detection function of three LEDs, which not only reduces the PCB area and facilitates product miniaturization design, but also makes the cost more favorable. [Attached Image Description]

[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0014] Figure 1 This is a functional block diagram of the LED open / short circuit detection circuit in one embodiment of the present invention;

[0015] Figure 2In one embodiment of this utility model, as shown Figure 1 The circuit diagram of the LED control circuit shown is shown.

[0016] Figure 3 In one embodiment of this utility model, as shown Figure 1 and Figure 2 The RGB point color control and diagnostic acquisition timing diagram is shown below.

[0017] Figure 4 In one embodiment of this utility model, as shown Figure 1 and Figure 2 The flowchart shown is for RGB point color control and diagnostic acquisition.

[0018] Figure 5 In another embodiment of this utility model, such as Figure 1 The circuit diagram of the LED control circuit shown is shown.

[0019] Figure 6 In one embodiment of this utility model, as shown Figure 1 and Figure 5 The RGB logic control and diagnostic acquisition timing diagram is shown below;

[0020] Figure 7 In one embodiment of this utility model, as shown Figure 1 and Figure 5 The diagram shows the logic for implementing RGB diagnostics.

Detailed Implementation Methods

[0021] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms coupling, connection, linking, and interconnection used herein to indicate electrical connection mean direct or indirect connection. For example, A being connected to B includes both a direct electrical connection between A and B and a connection between A and B via electrical components or circuits.

[0023] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "back", "positive", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] Please refer to Figure 1 As shown, it is a functional block diagram of the LED open / short circuit detection circuit in one embodiment of the present invention. Figure 1 The open / short circuit detection circuit for LEDs shown includes an LED lamp group 110, a microcontroller 120, and an LED control circuit 130.

[0025] The LED light group 110 includes a first LED branch, a second LED branch, and a third LED branch. Figure 1 In the specific embodiment shown, the LED light group 110 is an RGB LED (i.e., a three-primary-color LED), and the first LED branch, the second LED branch, and the third LED branch are Blue_LED, Green_LED, and RED_LED, respectively.

[0026] The microcontroller 120 outputs a first control signal LED0 at its first output terminal, a second control signal LED1 at its second output terminal, and a third control signal LED2 at its third output terminal. Its voltage sampling terminal ADC_OS is used to sample the voltage. Figure 1 In the specific embodiment shown, the microcontroller 120 is an ASIC (Application Specific Integrated Circuit).

[0027] Figure 1 The open / short circuit detection circuit for the LED shown also includes a DC-DC converter module (i.e., DCDC module) 140, an input filter and anti-reverse circuit 150, and an input connector 160.

[0028] The DC-DC converter module (DCDC module) 140 converts the input DC voltage VS supply into DC voltages Vdcdc at different voltage levels. The DC voltage Vdcdc output by the DC-DC converter module 140 is connected to the power supply terminal Vdcdc of the LED control circuit (or RGB control circuit) 130. The input filtering and reverse protection circuit 150 is connected to the input power supply and outputs the DC voltage VS supply. The input filtering and reverse protection circuit 150 performs output filtering and reverse protection processing on the input power supply to obtain the DC voltage VS supply. The power supply terminal of the microcontroller (or ASIC) 120 is connected to the DC voltage VS supply output by the input filtering and reverse protection circuit 150. The microcontroller (or ASIC) 120 outputs an enable signal DCDC-EN to the DC-DC converter module (DCDC module) 140 to control whether the DC-DC converter module (DCDC module) 140 is working.

[0029] Input connector 160 provides input power to the input terminal of input filtering and anti-reverse circuit 150; input connector 160 communicates with microcontroller (or ASIC) 120 via LIN bus (e.g., LIN and LIN_AA).

[0030] exist Figure 1 In the specific embodiment shown, the LED control circuit 130 is an RGB control circuit. Please refer to... Figure 2 As shown, this is one embodiment of the present invention. Figure 1 The diagram shows a schematic of the LED control circuit. Figure 2The LED control circuit shown includes a drive control circuit 132 and a voltage sampling circuit 134. The drive control circuit 132 includes three switching transistors Q1, Q2, and Q3. The first terminal of switching transistor Q1 is connected to the power supply terminal Vdcdc, and its control terminal is connected to the first output terminal of the microcontroller 120 (or the first control signal LED0). Its second terminal is connected to the positive terminal of the first LED branch (or Blue_LED), and the negative terminal of the first LED branch (or Blue_LED) is grounded. The first terminal of switching transistor Q2 is connected to the power supply terminal Vdcdc, and its control terminal is connected to the second output terminal of the microcontroller 120. The first terminal of the switch transistor Q3 is connected to the power supply terminal Vdcdc, its control terminal is connected to the third output terminal of the microcontroller 120 (or the third control signal LED2), its second terminal is connected to the positive terminal of the third LED branch (or RED_LED), and the negative terminal of the third LED branch (or RED_LED) is grounded; the first terminal of the switch transistor Q3 is connected to the power supply terminal Vdcdc, its control terminal is connected to the third output terminal of the microcontroller 120 (or the third control signal LED2), its second terminal is connected to the positive terminal of the third LED branch (or RED_LED), and the negative terminal of the third LED branch (or RED_LED) is grounded. The voltage sampling circuit 134 is used to connect the positive terminals of the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED) one by one to the voltage sampling terminal ADC_OS of the microcontroller 120, so that the microcontroller 120 can sample the voltage of any one of the positive terminals of the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED) through the voltage sampling terminal ADC_OS.

[0031] exist Figure 2In the illustrated embodiment, the drive control circuit 132 further includes resistors R1, R2, R3, R7, R8, R9, R13, R14, and R15. One end of resistor R1 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of the switching transistor Q1; one end of resistor R7 is connected to the control terminal of the switching transistor Q1, and the other end is connected to the first output terminal (or the first control signal LED0) of the microcontroller 120; one end of resistor R15 is connected to the second connection terminal of the switching transistor Q1, and the other end is connected to the positive terminal of the first LED branch (or Blue_LED); one end of resistor R2 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of the switching transistor Q2; one end of resistor R8 is connected to the control terminal of the switching transistor Q2, and the other end is connected to the... The second output terminal (or the second control signal LED1) is connected; one end of resistor R13 is connected to the second connection terminal of switch Q2, and the other end is connected to the positive terminal of the second LED branch (or Green_LED); one end of resistor R3 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of switch Q3; one end of resistor R9 is connected to the control terminal of switch Q3, and the other end is connected to the third output terminal (or the third control signal LED2) of microcontroller 120; one end of resistor R14 is connected to the second connection terminal of switch Q3, and the other end is connected to the positive terminal of the third LED branch (or RED_LED).

[0032] exist Figure 2 In the embodiment shown, the voltage sampling circuit 134 includes resistors R16, R17, R18, R22, R23, R24, and R29, diodes D1, D2, and D3, and switching transistors Q7, Q8, and Q9.

[0033] Among them, one end of resistor R16 is connected to the first output terminal (or the first control signal LED0) of microcontroller 120, and the other end is connected to the control terminal of switch Q7; the first connection terminal of switch Q7 is connected to the positive terminal of the first LED branch (or Blue_LED), and the second connection terminal is connected to the voltage sampling terminal ADC_OS of microcontroller 120; one end of resistor R22 is connected to the positive terminal of the first LED branch (or Blue_LED), and the other end is connected to the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the control terminal of switch Q7. One end of resistor R17 is connected to the second output terminal (or the second control signal LED1) of microcontroller 120, and the other end is connected to the control terminal of switch Q8; the first connection terminal of switch Q8 is connected to the positive terminal of the second LED branch (or Green_LED), and its second connection terminal is connected to the voltage sampling terminal ADC_OS of microcontroller 120; one end of resistor R23 is connected to the positive terminal of the second LED branch (or Green_LED), and the other end is connected to the positive terminal of diode D2; the negative terminal of diode D2 is connected to the control terminal of switch Q8. The resistor R18 is connected at one end to the third output terminal (or the third control signal LED2) of the microcontroller 120, and at the other end to the control terminal of the switching transistor Q9. The first connection terminal of the switching transistor Q9 is connected to the positive terminal of the third LED branch (or RED_LED), and its second connection terminal is connected to the voltage sampling terminal ADC_OS of the microcontroller 120. One end of the resistor R24 ​​is connected to the positive terminal of the third LED branch (or RED_LED), and at the other end is connected to the positive terminal of the diode D3. The negative terminal of the diode D3 is connected to the control terminal of the switching transistor Q9. One end of the resistor R29 is connected to the voltage sampling terminal ADC_OS of the microcontroller 120, and the other end is grounded.

[0034] When the first control signal LED0 is valid and the second control signal LED1 and the third control signal LED2 are invalid, switches Q1 and Q7 are turned on, switches Q2 and Q8 are turned off, and switches Q3 and Q9 are turned off. The voltage sampling circuit 134 connects the voltage sampling terminal ADC_OS of the microcontroller 120 to the positive terminal of the first LED branch (or Blue_LED). At this time, the first LED branch (or Blue_LED) is lit, and the second LED branch (or Green_LED) and the third LED branch (or RED_LED) are turned off. The microcontroller 120 samples the voltage of the positive terminal of the first LED branch (or Blue_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the first LED branch (or Blue_LED).

[0035] When the second control signal LED1 is valid and the first control signal LED0 and the third control signal LED2 are invalid, switches Q2 and Q8 are turned on, switches Q1 and Q7 are turned off, and switches Q3 and Q9 are turned off. The voltage sampling circuit 134 connects the voltage sampling terminal ADC_OS of the microcontroller 120 to the positive terminal of the second LED branch (or Green_LED). At this time, the second LED branch (or Green_LED) is lit, and the first LED branch (or Blue_LED) and the third LED branch (or RED_LED) are turned off. The microcontroller 120 samples the voltage of the positive terminal of the second LED branch (or Green_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the second LED branch (or Green_LED).

[0036] When the third control signal LED2 is valid and the first control signal LED0 and the second control signal LED1 are invalid, switches Q3 and Q9 are turned on, switches Q1 and Q7 are turned off, and switches Q2 and Q8 are turned off. The voltage sampling circuit 134 connects the voltage sampling terminal ADC_OS of the microcontroller 120 to the positive terminal of the third LED branch (or RED_LED). At this time, the third LED branch (or RED_LED) is lit, and the first LED branch (or Blue_LED) and the second LED branch (or Green_LED) are turned off. The microcontroller 120 samples the voltage of the positive terminal of the third LED branch (or RED_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the third LED branch (or RED_LED).

[0037] When an open circuit or short circuit is detected in at least one of the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED), the microcontroller 120 controls the first control signal LED0, the second control signal LED1, and the third control signal LED2 to be invalid, causing the switching transistors Q1, Q2, Q3, Q7, Q8, and Q9 to be turned off, thereby turning off the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED).

[0038] exist Figure 2In the specific embodiment shown, switch Q1 is a PNP transistor, and its first connection terminal, second connection terminal, and control terminal are the emitter, collector, and base of the PNP transistor, respectively; switch Q2 is a PNP transistor, and its first connection terminal, second connection terminal, and control terminal are the emitter, collector, and base of the PNP transistor, respectively; switch Q3 is a PNP transistor, and its first connection terminal, second connection terminal, and control terminal are the emitter, collector, and base of the PNP transistor, respectively. The transistors are: emitter, collector, and base; switch Q7 is a PNP transistor, with its first connection terminal, second connection terminal, and control terminal being the emitter, collector, and base of the PNP transistor, respectively; switch Q8 is a PNP transistor, with its first connection terminal, second connection terminal, and control terminal being the emitter, collector, and base of the PNP transistor, respectively; switch Q9 is a PNP transistor, with its first connection terminal, second connection terminal, and control terminal being the emitter, collector, and base of the PNP transistor, respectively.

[0039] against Figure 2 The LED control circuit shown needs special explanation as follows:

[0040] 1) Vdcdc is the output voltage of the DC-DC converter;

[0041] 2) The first control signal LED0, the second control signal LED1, and the third control signal LED2 are PWM (Pulse Width Modulation) signals output by the control register of the MCU (or ASIC). When the PWM signal is low (which can be called the effective level), the corresponding LED branch is lit. At the same time, the positive terminal of the LED branch is sampled by the ADC through the voltage sampling terminal ADC_OS. When the PWM signal is high (which can be called the ineffective level), the corresponding LED branch is not lit.

[0042] 3) The voltage sampling terminal ADC_OS is the ADC acquisition input port of the MCU (or ASIC);

[0043] 4) In the drive control circuit 132,

[0044] ● The function of resistors R13, R14 and R15 is to limit the current of Blue_LED, Green_LED and RED_LED when the power supply is Vdcdc at the power supply terminal;

[0045] ● Transistors Q1, Q2, and Q3 are used to modulate and switch the LEDs on and off. When the first control signal LED0 is low, transistor Q1 is on, and the Blue LED lights up. When the second control signal LED1 is low, transistor Q2 is on, and the Green LED lights up. When the third control signal LED2 is low, transistor Q3 is on, and the Red LED lights up. Conversely, when transistors Q1, Q2, and Q3 are on (or off), the corresponding LEDs are off.

[0046] ● The function of resistors R1, R2, R3, R7, R8 and R9 is to provide a fixed voltage when transistors Q1, Q2 and Q3 are turned off to prevent erroneous output.

[0047] 5) In the voltage sampling circuit 134,

[0048] ● The function of resistor R29 is to form a low-pass filter with the capacitor at the IC terminal to ensure accurate data acquisition;

[0049] ● The function of diodes D1, D2, and D3 is to prevent the voltage at the power supply terminal Vdcdc from forming a path between the resistor and Blue_LED, Green_LED, and RED_LED. When the MCU (or ASIC) controls the transistors Q1, Q2, and Q3 to be turned off, Blue_LED, Green_LED, and RED_LED will light up because the first control signal LED0, the second control signal LED1, and the third control signal LED2 are open-drain outputs.

[0050] ● Transistors Q7, Q8, and Q9 are used in conjunction with the MCU (or ASIC) control terminals. When only the first control signal LED0 is low, transistor Q7 is turned on, and the ADC_OS outputs the voltage of Blue_LED. When only the second control signal LED1 is low, transistor Q8 is turned on, and the ADC_OS outputs the voltage of Green_LED. When only the third control signal LED2 is low, transistor Q9 is turned on, and the ADC_OS outputs the voltage of RED_LED.

[0051] Please refer to Figure 3 As shown, this is one embodiment of the present invention. Figure 1 and Figure 2 The diagram shows the timing sequence for RGB point color control and diagnostic data acquisition. Tcycle represents the RGB lighting cycle; ① represents the red light activation and red light voltage acquisition time; ② represents the green light activation and green light voltage acquisition time; ③ represents the blue light activation and blue light voltage acquisition time.

[0052] Please refer to Figure 4As shown, this is one embodiment of the present invention. Figure 1 and Figure 2 The flowchart shown is for RGB point color control and diagnostic acquisition.

[0053] based on Figure 3 and Figure 4 It can be seen that within one Tcycle, the third control signal LED2 is pulled low sequentially, turning on transistors Q3 and Q9, illuminating the RED_LED and causing the ADC_OS to sample the red LED voltage; after the RED_LED is lit, the third control signal LED2 is pulled high, and the second control signal LED1 is pulled low, turning on transistors Q2 and Q8, illuminating the Green_LED and causing the ADC_OS to sample the green LED voltage; after the Green LED is lit, the second control signal LED1 is pulled high, and the first control signal LED0 is pulled low, turning on transistors Q1 and Q7, illuminating the Blue_LED and causing the ADC_OS to sample the blue LED voltage. This concludes one Tcycle. The MCU (or ASIC) has completed the acquisition of the red, green, and blue LED voltages and compared the acquired values ​​with the preset open-circuit and short-circuit thresholds for each LED. If the voltage is less than the open-circuit threshold and greater than the short-circuit threshold, the LED is considered normal, and the cycle continues to the next Tcycle. If the voltage is greater than the open-circuit threshold, the LED is considered open-circuited; if it is less than the short-circuit threshold, the LED is considered short-circuited. If the MCU (or ASIC) determines that an LED has an open or short circuit, it will pull the control signals LED2, LED1, and LED0 high, turning off transistors Q1, Q2, and Q3, thus extinguishing the red, green, and blue LEDs and preventing the fault caused by the open or short circuit from escalating further.

[0054] In summary, the present utility model provides the following... Figure 1 and Figure 2 The LED open / short circuit shown can use a single ADC sampling port to perform open / short circuit diagnosis on the three branches of the RGB components when the high-power ambient light product is working. It has the following beneficial effects:

[0055] 1) Without affecting the brightness and color of RGB, the MCU (or ASIC) diagnoses faults through timing position transformation logic;

[0056] 2) Only one ADC sampling is needed to realize the open circuit and short circuit fault detection function of 3-channel RGB;

[0057] 3) The fault diagnosis of the current channel will not be affected if there is an open circuit or short circuit fault in an adjacent channel;

[0058] 4) The linkage of MCU (or ASIC) controlling dual transistors not only provides anti-reverse current protection for lighting, but also allows the MCU (or ASIC) to acquire a wider range of RGB voltages, thus reducing the false alarm rate.

[0059] 5) Compared to the control of multi-channel ADC sampling, the technical solution provided by this utility model is more cost-effective;

[0060] 6) Compared with the control of multi-channel ADC sampling, the technical solution provided by this utility model occupies less PCB area, which is more conducive to product miniaturization design.

[0061] Please refer to Figure 5 As shown, this is another embodiment of the present invention. Figure 1 The diagram shows a schematic of the LED control circuit. Figure 5 The LED control circuit shown includes a drive control circuit 232 and a voltage sampling circuit 234. Among them, Figure 5 The drive control circuit 232 shown and Figure 2 The circuit structure of the drive control circuit 132 shown is exactly the same. For details, please refer to the previous description of the drive control circuit 132, so it will not be repeated here.

[0062] exist Figure 5 In the illustrated embodiment, the voltage sampling circuit 234 includes resistors R25, R26, R27, and R28, diodes D4, D5, and D6. One end of resistor R25 is connected to the positive terminal of the first LED branch (or Blue_LED), and the other end is connected to the positive terminal of diode D4. The negative terminal of diode D4 is connected to the voltage sampling terminal ADC_OS of the microcontroller 120. One end of resistor R26 is connected to the positive terminal of the second LED branch (or Green_LED), and the other end is connected to the positive terminal of diode D5. The negative terminal of diode D5 is connected to the voltage sampling terminal ADC_OS of the microcontroller 120. One end of resistor R27 is connected to the positive terminal of the third LED branch (or RED_LED), and the other end is connected to the positive terminal of diode D6. The negative terminal of diode D6 is connected to the voltage sampling terminal ADC_OS of the microcontroller 120. One end of resistor R28 is connected to the voltage sampling terminal ADC_OS of the microcontroller 120, and the other end is grounded.

[0063] When the first control signal LED0 is valid and the second control signal LED1 and the third control signal LED2 are invalid, switch Q1 and diode D4 are turned on, switch Q2 and diode D5 are turned off, and switch Q3 and diode D6 are turned off. Voltage sampling circuit 234 connects the voltage sampling terminal ADC_OS of microcontroller 120 to the positive terminal of the first LED branch (or Blue_LED). At this time, the first LED branch (or Blue_LED) is lit, and the second LED branch (or Green_LED) and the third LED branch (or RED_LED) are turned off. Microcontroller 120 samples the voltage of the positive terminal of the first LED branch (or Blue_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the first LED branch (or Blue_LED).

[0064] When the second control signal LED1 is valid and the first control signal LED0 and the third control signal LED2 are invalid, switch Q2 and diode D5 are turned on, switch Q1 and diode D4 are turned off, and switch Q3 and diode D6 are turned off. Voltage sampling circuit 234 connects the voltage sampling terminal ADC_OS of microcontroller 120 to the positive terminal of the second LED branch (or Green_LED). At this time, the second LED branch (or Green_LED) is lit, and the first LED branch (or Blue_LED) and the third LED branch (or RED_LED) are turned off. Microcontroller 120 samples the voltage of the positive terminal of the second LED branch (or Green_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the second LED branch (or Green_LED).

[0065] When the third control signal LED2 is valid and the first control signal LED0 and the second control signal LED1 are invalid, switch Q3 and diode D6 are turned on, switch Q1 and diode D4 are turned off, and switch Q2 and diode D5 are turned off. Voltage sampling circuit 234 connects the voltage sampling terminal ADC_OS of microcontroller 120 to the positive terminal of the third LED branch (or RED_LED). At this time, the third LED branch (or RED_LED) is lit, and the first LED branch (or Blue_LED) and the second LED branch (or Green_LED) are turned off. Microcontroller 120 samples the voltage of the positive terminal of the third LED branch (or RED_LED) through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the third LED branch (or RED_LED).

[0066] When an open circuit or short circuit is detected in at least one of the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED), the microcontroller 120 controls the first control signal LED0, the second control signal LED1, and the third control signal LED2 to be invalid, causing the switching transistors Q1, Q2, and Q3 to be turned off, thereby turning off the first LED branch (or Blue_LED), the second LED branch (or Green_LED), and the third LED branch (or RED_LED).

[0067] exist Figure 5 In the specific embodiment shown, switch Q1 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of switch Q1 are the emitter, collector, and base of the PNP transistor, respectively; switch Q2 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of switch Q2 are the emitter, collector, and base of the PNP transistor, respectively; switch Q3 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of switch Q3 are the emitter, collector, and base of the PNP transistor, respectively.

[0068] against Figure 5 The LED control circuit shown needs special explanation as follows:

[0069] 1) Vdcdc is the output voltage of the DC-DC converter;

[0070] 2) The first control signal LED0, the second control signal LED1, and the third control signal LED2 are PWM (Pulse Width Modulation) signals output by the control register of the MCU (or ASIC). When the PWM signal is low (which can be called the effective level), the corresponding LED branch is lit. At the same time, the positive terminal of the LED branch is sampled by the ADC through the voltage sampling terminal ADC_OS. When the PWM signal is high (which can be called the ineffective level), the corresponding LED branch is not lit.

[0071] 3) The voltage sampling terminal ADC_OS is the ADC acquisition input port of the MCU (or ASIC);

[0072] 4) In the drive control circuit 232,

[0073] ● The function of resistors R13, R14 and R15 is to limit the current of Blue_LED, Green_LED and RED_LED when the power supply is Vdcdc at the power supply terminal;

[0074] ● Transistors Q1, Q2, and Q3 are used to modulate and switch the LEDs on and off. When the first control signal LED0 is low, transistor Q1 is on, and the Blue LED lights up. When the second control signal LED1 is low, transistor Q2 is on, and the Green LED lights up. When the third control signal LED2 is low, transistor Q3 is on, and the Red LED lights up. Conversely, when transistors Q1, Q2, and Q3 are on (or off), the corresponding LEDs are off.

[0075] ● The function of resistors R1, R2, R3, R7, R8 and R9 is to provide a fixed voltage when transistors Q1, Q2 and Q3 are turned off to prevent erroneous output.

[0076] 5) In the voltage sampling circuit 234,

[0077] ● The function of resistor R28 is to form a low-pass filter with the capacitor at the IC terminal to ensure accurate data acquisition;

[0078] ● The function of diodes D4, D5, and D6 is to prevent the high voltage of the LED from flowing back into the low voltage LED, causing the low voltage LED to light up dimly.

[0079] Please refer to Figure 6 As shown, this is one embodiment of the present invention. Figure 1 and Figure 5 The diagram shows the RGB logic control and diagnostic acquisition timing. Tcycle represents the RGB lighting cycle; ① is the time to check if the red light is working properly; ② is the time to check if the green light is working properly; ③ is the time to check if the blue light is working properly; ④ is the stage of lighting up two mixed colors; ⑤ is the stage of lighting up a single color; and ⑥ is the stage of lighting up three mixed colors. When the RGB colors and brightness are fixed, regardless of whether it's lighting up a single color (⑤), two mixed colors (④), or three mixed colors (⑥), fault diagnosis for that color is performed by judging the falling edge of the RGB light in each cycle as the trigger flag. That is, under a given color, the fault status of the RGB three-channel LEDs is diagnosed by continuously changing the position of the falling edge of the RGB light within a cycle while keeping the duty cycle constant throughout the cycle. It should be noted that... Figure 6 The image shows one type of color-coded LED control method. The duty cycle and the number of data acquisition and diagnostic points can be adjusted according to the different colors of the LEDs, but the underlying principle is the same as... Figure 6 Same as shown.

[0080] Please refer to Figure 7 As shown, this is one embodiment of the present invention. Figure 1 and Figure 5The RGB diagnostic implementation logic diagram shown is as follows: "1" represents that the ADC_OS reads a high level, and "0" represents that the ADC_OS reads a low level.

[0081] based on Figure 6 and Figure 7 As can be seen, when the circuit is powered on, the control signals LED0, LED1, and LED2 are all at a low level, transistors Q1, Q2, and Q3 are turned on, and all three RGB branch lights illuminate. Subsequently, the MCU (or ASIC) controls LED0, LED1, and LED2 to be at a high level, and transistors Q1, Q2, and Q3 are turned off. At this time, the ADC_OS sampling is at a low level. Since only a single-port ADC_OS sampling port samples the voltage, when the MCU (or ASIC) needs to control the sampling of different LED voltages, it can only make the control signal of one LED low, while the control signals of the remaining two LEDs are high. When the MCU (or ASIC) detects a falling edge on the third control signal LED2, the second control signal LED1 and the first control signal LED0 are high. The ADC_OS sampling can only measure the voltage drop of LED2. If the voltage sampled by the ADC_OS is low (the low-level threshold needs to be set according to the actual design), LED2 is considered to be in an open-circuit state. If the voltage sampled by the ADC_OS is high (the high-level threshold needs to be set according to the actual design), LED2 is considered to be in a short-circuit state. If the voltage sampled by the ADC_OS is between low and high, it indicates that LED2 is working normally and there is no open-circuit or short-circuit situation. The judgment method for LED1 and LED0 is similar to the above, and the working state of LED1 and LED0 can be determined, so it will not be repeated. According to the above description, the circuit is periodic, so only one ADC is used to periodically sample the voltage of the three RGB LED branches, thereby determining the open-circuit and short-circuit states of the three LEDs.

[0082] In summary, the present utility model provides the following... Figure 1 and Figure 5 The LED open / short circuit shown can use a single ADC sampling port to perform open / short circuit diagnosis on the three branches of the RGB components when the high-power ambient light product is working. It has the following beneficial effects:

[0083] 1) Without affecting the brightness and color of RGB, the MCU (or ASIC) diagnoses faults through timing position transformation logic;

[0084] 2) Only one ADC sampling is needed to realize the open circuit and short circuit fault detection function of 3-channel RGB;

[0085] 3) The fault diagnosis of the current channel will not be affected if there is an open circuit or short circuit fault in an adjacent channel;

[0086] 4) The voltage sampling circuit 234 effectively prevents backflow from affecting the output results due to differences in RGB voltages while ensuring correct acquisition.

[0087] 5) Compared to the control of multi-channel ADC sampling, the technical solution provided by this utility model is more cost-effective;

[0088] 6) Compared with the control of multi-channel ADC sampling, the technical solution provided by this utility model occupies less PCB area, which is more conducive to product miniaturization design.

[0089] It should be noted that any modifications made by those skilled in the art to the specific embodiments of this utility model do not depart from the scope of the claims of this utility model. Accordingly, the scope of the claims of this utility model is not limited to the foregoing specific embodiments.

Claims

1. An open / short circuit detection circuit for an LED, characterized in that, It includes: The LED light assembly includes a first LED branch, a second LED branch, and a third LED branch; The microcontroller outputs a first control signal LED0 at its first output terminal, a second control signal LED1 at its second output terminal, and a third control signal LED2 at its third output terminal. Its voltage sampling terminal ADC_OS is used to sample voltage. The LED control circuit includes a drive control circuit and a voltage sampling circuit. The drive control circuit includes three switching transistors: Q1, Q2, and Q3. The first terminal of switching transistor Q1 is connected to the power supply terminal Vdcdc, its control terminal is connected to the first output terminal of the microcontroller, and its second terminal is connected to the positive terminal of the first LED branch, while the negative terminal of the first LED branch is grounded. The first terminal of switching transistor Q2 is connected to the power supply terminal Vdcdc, its control terminal is connected to the second output terminal of the microcontroller, and its second terminal is connected to the positive terminal of the second LED branch, while the negative terminal of the second LED branch is grounded. The first connection terminal of tube Q3 is connected to the power supply terminal Vdcdc, its control terminal is connected to the third output terminal of the microcontroller, its second connection terminal is connected to the positive terminal of the third LED branch, and the negative terminal of the third LED branch is grounded; the voltage sampling circuit is used to connect the positive terminals of the first LED branch, the second LED branch, and the third LED branch one by one to the voltage sampling terminal ADC_OS of the microcontroller, so that the microcontroller can sample the voltage of any one of the positive terminals of the first LED branch, the second LED branch, and the third LED branch through the voltage sampling terminal ADC_OS.

2. The LED open / short circuit detection circuit according to claim 1, characterized in that, The drive control circuit also includes resistors R1, R2, R3, R7, R8, R9, R13, R14, and R15. One end of resistor R1 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of the switching transistor Q1; one end of resistor R7 is connected to the control terminal of the switching transistor Q1, and the other end is connected to the first output terminal of the microcontroller; one end of resistor R15 is connected to the second connection terminal of the switching transistor Q1, and the other end is connected to the positive terminal of the first LED branch. One end of resistor R2 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of the switching transistor Q2; one end of resistor R8 is connected to the control terminal of the switching transistor Q2, and the other end is connected to the second output terminal of the microcontroller; one end of resistor R13 is connected to the second connection terminal of the switching transistor Q2, and the other end is connected to the positive terminal of the second LED branch. One end of resistor R3 is connected to the power supply terminal Vdcdc, and the other end is connected to the control terminal of the switching transistor Q3; one end of resistor R9 is connected to the control terminal of the switching transistor Q3, and the other end is connected to the third output terminal LED2 of the microcontroller; one end of resistor R14 is connected to the second connection terminal of the switching transistor Q3, and the other end is connected to the positive terminal of the third LED branch.

3. The LED open / short circuit detection circuit according to claim 2, characterized in that, The voltage sampling circuit includes resistors R16, R17, R18, R22, R23, R24, and R29, diodes D1, D2, and D3, and switching transistors Q7, Q8, and Q9. One end of resistor R16 is connected to the first output terminal of the microcontroller, and the other end is connected to the control terminal of the switching transistor Q7; the first connection terminal of the switching transistor Q7 is connected to the positive terminal of the first LED branch, and the second connection terminal is connected to the voltage sampling terminal ADC_OS of the microcontroller; one end of resistor R22 is connected to the positive terminal of the first LED branch, and the other end is connected to the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the control terminal of the switching transistor Q7. One end of resistor R17 is connected to the second output terminal of the microcontroller, and the other end is connected to the control terminal of the switching transistor Q8; the first connection terminal of the switching transistor Q8 is connected to the positive terminal of the second LED branch, and the second connection terminal is connected to the voltage sampling terminal ADC_OS of the microcontroller; one end of resistor R23 is connected to the positive terminal of the second LED branch, and the other end is connected to the positive terminal of diode D2, and the negative terminal of diode D2 is connected to the control terminal of the switching transistor Q8. One end of resistor R18 is connected to the third output terminal of the microcontroller, and the other end is connected to the control terminal of the switching transistor Q9; the first connection terminal of the switching transistor Q9 is connected to the positive terminal of the third LED branch, and the second connection terminal is connected to the voltage sampling terminal ADC_OS of the microcontroller; one end of resistor R24 ​​is connected to the positive terminal of the third LED branch, and the other end is connected to the positive terminal of diode D3, and the negative terminal of diode D3 is connected to the control terminal of the switching transistor Q9. One end of the resistor R29 is connected to the voltage sampling terminal ADC_OS of the microcontroller, and the other end is grounded.

4. The LED open / short circuit detection circuit according to claim 3, characterized in that, When the first control signal LED0 is valid and the second control signal LED1 and the third control signal LED2 are invalid, the switching transistors Q1 and Q7 are turned on, the switching transistors Q2 and Q8 are turned off, and the switching transistors Q3 and Q9 are turned off. The voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the first LED branch. At this time, the first LED branch is lit, and the second and third LED branches are turned off. The microcontroller samples the voltage of the positive terminal of the first LED branch through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the first LED branch. When the second control signal LED1 is valid and the first control signal LED0 and the third control signal LED2 are invalid, the switching transistors Q2 and Q8 are turned on, the switching transistors Q1 and Q7 are turned off, and the switching transistors Q3 and Q9 are turned off. The voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the second LED branch. At this time, the second LED branch is lit, and the first LED branch and the third LED branch are turned off. The microcontroller samples the voltage of the positive terminal of the second LED branch through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the second LED branch. When the third control signal LED2 is valid and the first control signal LED0 and the second control signal LED1 are invalid, the switching transistors Q3 and Q9 are turned on, the switching transistors Q1 and Q7 are turned off, and the switching transistors Q2 and Q8 are turned off. The voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the third LED branch. At this time, the third LED branch is lit, and the first LED branch and the second LED branch are turned off. The microcontroller samples the voltage of the positive terminal of the third LED branch through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the third LED branch.

5. The LED open / short circuit detection circuit according to claim 4, characterized in that, When an open circuit or short circuit is detected in at least one of the first LED branch, the second LED branch, and the third LED branch, the microcontroller controls the first control signal LED0, the second control signal LED1, and the third control signal LED2 to be invalid, thereby turning off the switching transistors Q1, Q2, Q3, Q7, Q8, and Q9, and thus extinguishing the first LED branch, the second LED branch, and the third LED branch.

6. The LED open / short circuit detection circuit according to claim 3, characterized in that, The switching transistor Q1 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q1 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q2 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q2 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q3 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q3 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q7 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q7 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q8 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q8 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q9 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q9 are the emitter, collector, and base of the PNP transistor, respectively.

7. The LED open / short circuit detection circuit according to claim 2, characterized in that, The voltage sampling circuit includes resistors R25, R26, R27, and R28, diodes D4, D5, and D6. One end of resistor R25 is connected to the positive terminal of the first LED branch, and the other end is connected to the positive terminal of diode D4. The negative terminal of diode D4 is connected to the voltage sampling terminal ADC_OS of the microcontroller. One end of resistor R26 is connected to the positive terminal of the second LED branch, and the other end is connected to the positive terminal of diode D5. The negative terminal of diode D5 is connected to the voltage sampling terminal ADC_OS of the microcontroller. One end of resistor R27 is connected to the positive terminal of the third LED branch, and the other end is connected to the positive terminal of diode D6. The negative terminal of diode D6 is connected to the voltage sampling terminal ADC_OS of the microcontroller. One end of resistor R28 is connected to the voltage sampling terminal ADC_OS of the microcontroller, and the other end is grounded.

8. The LED open / short circuit detection circuit according to claim 7, characterized in that, When the first control signal LED0 is valid and the second control signal LED1 and the third control signal LED2 are invalid, the switch Q1 and diode D4 are turned on, the switch Q2 and diode D5 are turned off, the switch Q3 and diode D6 are turned off, and the voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the first LED branch. At this time, the first LED branch is lit, and the second and third LED branches are turned off. The microcontroller samples the voltage of the positive terminal of the first LED branch through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the first LED branch. When the second control signal LED1 is valid and the first control signal LED0 and the third control signal LED2 are invalid, the switch Q2 and diode D5 are turned on, the switch Q1 and diode D4 are turned off, and the switch Q3 and diode D6 are turned off. The voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the second LED branch. At this time, the second LED branch is lit, and the first and third LED branches are turned off. The microcontroller samples the voltage of the positive terminal of the second LED branch through the voltage sampling terminal ADC_OS to control the voltage of the second LED branch. Perform open-circuit and short-circuit condition detection; When the third control signal LED2 is valid and the first control signal LED0 and the second control signal LED1 are invalid, the switch Q3 and diode D6 are turned on, the switch Q1 and diode D4 are turned off, and the switch Q2 and diode D5 are turned off. The voltage sampling circuit connects the voltage sampling terminal ADC_OS of the microcontroller to the positive terminal of the third LED branch. At this time, the third LED branch is lit, and the first LED branch and the second LED branch are turned off. The microcontroller samples the voltage of the positive terminal of the third LED branch through the voltage sampling terminal ADC_OS to detect the open circuit and short circuit status of the third LED branch.

9. The LED open / short circuit detection circuit according to claim 8, characterized in that, When an open circuit or short circuit is detected in at least one of the first LED branch, the second LED branch, and the third LED branch, the microcontroller controls the first control signal LED0, the second control signal LED1, and the third control signal LED2 to be invalid, thereby turning off the switching transistors Q1, Q2, and Q3, and thus extinguishing the first LED branch, the second LED branch, and the third LED branch.

10. The LED open / short circuit detection circuit according to claim 7, characterized in that, The switching transistor Q1 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q1 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q2 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q2 are the emitter, collector, and base of the PNP transistor, respectively. The switching transistor Q3 is a PNP transistor, and the first connection terminal, the second connection terminal, and the control terminal of the switching transistor Q3 are the emitter, collector, and base of the PNP transistor, respectively.

11. The LED open / short circuit detection circuit according to claim 1, characterized in that, It also includes: A DC-DC converter module converts the input DC voltage VS supply into DC voltage outputs of different voltage levels. The DC voltage output by the DC-DC converter module is connected to the power supply terminal Vdcdc of the LED control circuit. An input filtering and anti-reverse circuit is provided, with its input terminal connected to the input power supply and its output terminal outputting a DC voltage VSsupply. The input filtering and anti-reverse circuit is used to perform output filtering and anti-reverse processing on the input power supply to obtain the DC voltage VSsupply. The power supply terminal of the microcontroller is connected to the DC voltage VS supply output by the input filter and anti-reverse circuit; the microcontroller outputs an enable signal DCDC-EN to the DC-DC converter module to control whether the DC-DC converter module is working.

12. The LED open / short circuit detection circuit according to claim 11, characterized in that, It also includes input connectors, The input connector provides the input power to the input terminal of the input filtering and anti-reverse circuit; The input connector communicates with the microcontroller via a LIN bus.

13. The LED open / short circuit detection circuit according to claim 1, characterized in that, The LED light group is a tri-color LED.

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