Vehicle lamp fault detection circuit and its use method

Abstract

The present invention discloses a vehicle lamp fault detection circuit and a method for using the same, comprising: a control chip, and a first detection module, which comprises a first logic control circuit, a first sampling circuit and a first LED light source, the first logic control circuit and the first sampling circuit are both connected to the control chip, the input end of the first LED light source is connected to the first logic control circuit, and the output end of the first LED light source is connected to the first sampling circuit; a second detection module, which comprises a second logic control circuit, a second sampling circuit and a second LED light source, the second logic control circuit and the second sampling circuit are both connected to the control chip, the input end of the second LED light source is connected to the second logic control circuit, and the output end of the second LED light source is connected to the second sampling circuit. The present invention can not only save 70% to 80% of the cost, but also detect the fault of only a single LED lamp bead short circuit, which can further improve the detection accuracy and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle lamps, and in particular to a vehicle lamp fault detection circuit and a use method thereof. Background Art

[0002] Headlights are tools for vehicles to illuminate the road at night, and are also tools for issuing various vehicle driving signals. Headlights are generally divided into headlights, taillights, turn signals, fog lights, etc. At present, with the development of society, the requirements for headlights are getting higher and higher, and the functions that headlights need to have are increasing, and the communication is becoming more and more complicated. Therefore, it is necessary to detect the working status of headlights in real time.

[0003] Existing headlight fault detection generally adopts the "MCU+driver chip+LED" method (such as Figure 1 As shown), that is, the MCU collects the working status of the LED light source in real time through the driver chip. Each group of LED light sources needs to be connected to a driver chip, which detects and drives the LED. This detection scheme has at least the following defects: (1) The driver chip is expensive, and the number of driver chips used is large, which greatly increases the total cost of the car light. In addition, more driver chips will also take up more space, which is not conducive to EMC testing. (2) The driver chip can only detect the open circuit fault of the LED light source. When only some of the LED lamp beads in the LED light source are short-circuited, the driver chip is driven by constant current and cannot identify the short circuit fault of some or a single LED. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in order to solve the technical problem that the detection method of the prior art is high in cost and the detection result is inaccurate, the present invention provides a vehicle lamp fault detection circuit and a method for using the same, which can not only significantly reduce the cost but also improve the fault detection accuracy.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a vehicle lamp fault detection circuit, comprising:

[0006] Control chip, and

[0007] A first detection module, comprising a first logic control circuit, a first sampling circuit and a first LED light source, wherein the first logic control circuit and the first sampling circuit are both connected to the control chip, an input end of the first LED light source is connected to the first logic control circuit, and an output end of the first LED light source is connected to the first sampling circuit;

[0008] The second detection module includes a second logic control circuit, a second sampling circuit and a second LED light source, wherein the second logic control circuit and the second sampling circuit are both connected to the control chip, the input end of the second LED light source is connected to the second logic control circuit, and the output end of the second LED light source is connected to the second sampling circuit.

[0009] Furthermore, the first logic control circuit includes: an NMOS tube FQ4, a PMOS tube FQ3, and a resistor FR18, the gate of the NMOS tube FQ4 is connected to the control chip, the source of the NMOS tube FQ4 is grounded, the drain of the NMOS tube FQ4 is connected to the gate of the PMOS tube FQ3 through the resistor FR18, the source of the PMOS tube FQ3 is connected to a regulated power supply, and the drain of the PMOS tube FQ3 is connected to the input end of the first LED light source.

[0010] Furthermore, the first sampling circuit includes: a resistor FR30, a resistor FR31 and a resistor FR32, the resistor FR30 and the resistor FR32 are connected in series, one end of the resistor FR31 is connected to one end of the resistor FR32, the other end of the resistor FR31 is connected to the control chip, the other end of the resistor FR32 is grounded, and one end of the resistor FR30 is connected to the output end of the first LED light source.

[0011] Furthermore, the second logic control circuit includes: an NMOS tube RQ4, a PMOS tube RQ3, and a resistor RR18, the gate of the NMOS tube RQ4 is connected to the control chip, the source of the NMOS tube RQ4 is grounded, the drain of the NMOS tube RQ4 is connected to the gate of the PMOS tube RQ3 through the resistor RR18, the source of the PMOS tube RQ3 is connected to a regulated power supply, and the drain of the PMOS tube RQ3 is connected to the input end of the second LED light source.

[0012] Furthermore, the second sampling circuit includes: a resistor RR27, a resistor RR28 and a resistor RR29, the resistor RR27 and the resistor RR29 are connected in series, one end of the resistor RR28 is connected to one end of the resistor RR29, the other end of the resistor RR29 is connected to the control chip, the other end of the resistor RR29 is grounded, and one end of the resistor RR27 is connected to the output end of the second LED light source.

[0013] Furthermore, the first LED light source and the second LED light source each include a plurality of LED lamp beads, and the plurality of LED lamp beads are connected in series.

[0014] Furthermore, it also includes: a first drive circuit and a second drive circuit, the first drive circuit is connected to the output end of the first LED light source, and the second drive circuit is connected to the output end of the second LED light source.

[0015] The present invention also provides a method for using a vehicle lamp fault detection circuit, comprising the following steps:

[0016] S1, the control chip lights up the first LED light source by controlling the first logic control circuit; the control chip lights up the second LED light source by controlling the second logic control circuit;

[0017] S2, collecting the output voltage value V1 of the first LED light source through a first sampling circuit; collecting the output voltage value V3 of the second LED light source through a second sampling circuit;

[0018] S3, the control chip reads the divided voltage V2 of the first sampling circuit and the divided voltage V4 of the second sampling circuit in real time; the control chip converts the divided voltages V2 and V4 into digital signals ADC V2 and ADC V4 , the control chip converts the digital signal ADC V2 and ADC V4 The digital value thresholds are compared with the set digital value threshold ranges to determine whether the first LED light source and the second LED light source are faulty.

[0019] Furthermore, let the working voltage of a single LED bead be V_F and the voltage of the regulated power supply be DC out , then the output voltages V1 and V3 can be expressed as: V1 = DC out -0.1-n*V_F, V3=DC out -0.1-m*V_F, where 0.1 represents the voltage drop of the MOS tube, and n and m represent the number of LED beads;

[0020] According to the changes in the output voltages V1 and V3 of the LED lamp beads when they are in normal operation, short circuit, and open circuit, the voltage thresholds of the first LED light source and the second LED light source in the normal, short circuit, and open circuit states are set; and then the voltage thresholds are converted into digital thresholds to obtain the digital threshold range.

[0021] Furthermore, the calculation formula for converting voltage into digital signal is:

[0022]

[0023] Among them, 5 represents the reference voltage of the built-in ADC of the control chip, and α represents the number of bits of the built-in ADC of the control chip.

[0024] The beneficial effects of the present invention are:

[0025] The present invention adopts the method of "control chip + logic control circuit + sampling circuit" to realize the driving and detection of LED light source, eliminating the driving chip, which can not only save 70% to 80% of the cost, but also detect the fault of only a single LED lamp bead short circuit, which can further improve the detection accuracy and reliability. In addition, the logic control circuit and sampling resistor use micro components such as resistors, capacitors, MOS tubes, etc., which occupy a small area, can reduce the difficulty of PCB board layout and installation, and are also conducive to EMC testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0027] Figure 1 Schematic diagram of a detection circuit in the prior art.

[0028] Figure 2 is a circuit diagram of the detection circuit of the present invention.

[0029] Figure 3 It is a schematic diagram of the control chip of the present invention.

[0030] Figure 4 is a circuit diagram of a first logic control circuit of the present invention.

[0031] Figure 5 is a circuit diagram of a first sampling circuit of the present invention.

[0032] Figure 6 is a circuit diagram of a second logic control circuit of the present invention.

[0033] Figure 7 is a circuit diagram of a second sampling circuit of the present invention.

[0034] In the figure: 1. control chip; 21. first logic control circuit; 22. first sampling circuit; 23. first LED light source; 31. second logic control circuit; 32. second sampling circuit; 33. second LED light source; 4. first drive circuit; 5. second drive circuit. DETAILED DESCRIPTION

[0035] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] like Figures 2 to 7 As shown, the vehicle lamp fault detection circuit of the present invention comprises: a control chip 1, a first detection module and a second detection module. The first detection module comprises a first logic control circuit 21, a first sampling circuit 22 and a first LED light source 23. The first logic control circuit 21 and the first sampling circuit 22 are both connected to the control chip 1. The input end of the first LED light source 23 is connected to the first logic control circuit 21, and the output end of the first LED light source 23 is connected to the first sampling circuit 22. The second detection module comprises a second logic control circuit 31, a second sampling circuit 32 and a second LED light source 33. The second logic control circuit 31 and the second sampling circuit 32 are both connected to the control chip 1. The input end of the second LED light source 33 is connected to the second logic control circuit 31, and the output end of the second LED light source 33 is connected to the second sampling circuit 32.

[0039] In other words, the present invention controls the opening and closing of the LED light source through the logic control circuit. When the LED light source is lit, the output voltage value of the LED light source is collected in real time through the sampling circuit and sent to the control chip 1. The control chip 1 can judge the current working state of the LED light source according to the output voltage value of the LED light source. The detection circuit of the present invention omits the driver chip and adopts the method of "control chip + logic control circuit + sampling circuit + LED" to realize the control and detection of the LED light source. On the one hand, it can save 70% to 80% of the cost and meet the cost reduction needs of enterprises; on the other hand, it can detect the short circuit fault of a single LED lamp bead, which can improve the accuracy of LED light source fault detection.

[0040] It should be noted that the first LED light source 23 and the second LED light source 33 are different types of lamps, for example, the first LED light source 23 is a fog lamp, the second LED light source 33 is a reversing lamp, and so on. For example, the control chip 1 is an MCU, which includes 64 pins, wherein the first logic control circuit 21 is connected to the 27th pin of the control chip 1, the first sampling circuit 22 is connected to the 28th pin of the control chip 1, the second logic control circuit 31 is connected to the 29th pin of the control chip 1, and the second sampling circuit 32 is connected to the 30th pin of the control chip 1. It should be noted that the control chip 1 is powered by a 5V power module.

[0041] Specifically, the first logic control circuit 21 includes: an NMOS tube FQ4, a PMOS tube FQ3, and a resistor FR18. The gate of the NMOS tube FQ4 is connected to the control chip 1, the source of the NMOS tube FQ4 is grounded, the drain of the NMOS tube FQ4 is connected to the gate of the PMOS tube FQ3 through the resistor FR18, the source of the PMOS tube FQ3 is connected to the voltage-stabilized power supply, and the drain of the PMOS tube FQ3 is connected to the input end of the first LED light source 23. For example, the voltage-stabilized power supply can provide a stable 8.3V voltage to power the first LED light source 23. The control chip 1 can turn on the NMOS tube FQ4 through the twenty-seventh pin. When the NMOS tube FQ4 is turned on, the PMOS tube FQ3 will also be turned on, so that the voltage-stabilized power supply can be input to the first LED light source 23, and the first LED light source 23 is lit. Among them, the NMOS tube needs V G Greater than V S It will be turned on, while the PMOS tube needs V G Less than V SThe first logic control circuit 21 also includes: resistors FR19, FR20, capacitor FC5, resistor FR17 ​​and diode FD2. One end of the resistor FR19 is connected to the twenty-seventh pin of the control chip 1, and the other end of the resistor FR19 is connected to the gate of the NMOS tube FQ4. One end of the resistor FR20 is connected to the gate of the NMOS tube FQ4, and the other end of the resistor FR20 is grounded. The resistors FR19 and FR20 can play a role in current limiting. The cathode of the diode FD2 is connected to the voltage-stabilized power supply, the anode of the diode FD2 is connected to the gate of the PMOS tube FQ3, and the diode FD2 can play a role in preventing reverse connection. The two ends of the resistor FR17 ​​are connected to the gate and source of the PMOS tube FQ3, and the resistor FR17 ​​can play a role in current limiting. The capacitor FC5 is connected in parallel with the resistor FR17, and the capacitor FC5 can perform filtering. When the control chip 1 turns on the NMOS tube FQ4 through the twenty-seventh pin, the source voltage of the PMOS tube FQ3 is higher than the gate voltage, the PMOS tube FQ3 is turned on, and the current of the voltage-stabilized power supply can supply power to the first LED light source 23, and the first LED light source 23 is lit.

[0042] The first sampling circuit 22 includes: a resistor FR30, a resistor FR31 and a resistor FR32, the resistor FR30 and the resistor FR32 are connected in series, one end of the resistor FR31 is connected to one end of the resistor FR32, the other end of the resistor FR31 is connected to the control chip 1 (pin 28), the other end of the resistor FR32 is grounded, and one end of the resistor FR30 is connected to the output end of the first LED light source 23. The current flowing through the first LED light source 23 can pass through the first sampling circuit 22, and the resistors FR30 and FR32 can play a voltage dividing role. The output voltage of the first LED light source 23 is sent to the control chip 1 after being divided by the first sampling circuit 22. The first LED light source 23 includes a plurality of LED lamp beads, and the plurality of LED lamp beads are connected in series. When an LED lamp bead in the first LED light source 23 is open-circuited, the output voltage of the first LED light source 23 is 0V, and when an LED lamp bead in the first LED light source 23 is short-circuited, the output voltage of the first LED light source 23 will be greater than that in normal operation. When the output voltage of the first LED light source 23 changes, the voltage division on the first sampling circuit 22 will also change accordingly. Therefore, the control chip 1 can determine whether the first LED light source 23 has a short circuit or open circuit fault by reading the voltage on the first sampling circuit 22 .

[0043] Specifically, the second logic control circuit 31 includes: an NMOS tube RQ4, a PMOS tube RQ3, and a resistor RR18. The gate of the NMOS tube RQ4 is connected to the control chip 1, the source of the NMOS tube RQ4 is grounded, the drain of the NMOS tube RQ4 is connected to the gate of the PMOS tube RQ3 through the resistor RR18, the source of the PMOS tube RQ3 is connected to the voltage-stabilized power supply, and the drain of the PMOS tube RQ3 is connected to the input end of the second LED light source 33. For example, the voltage-stabilized power supply can provide a stable 8.3V voltage to power the second LED light source 33. The control chip 1 can turn on the NMOS tube RQ4 through the twenty-ninth pin. When the NMOS tube RQ4 is turned on, the PMOS tube RQ3 will also be turned on, so that the voltage-stabilized power supply can be input to the second LED light source 33, and the second LED light source 33 is lit. The second logic control circuit 31 also includes: resistors RR19, RR20, capacitor RC5, resistor RR17 and diode RD2, one end of resistor RR19 is connected to the 29th pin of control chip 1, the other end of resistor RR19 is connected to the gate of NMOS tube RQ4, one end of resistor RR20 is connected to the gate of NMOS tube RQ4, the other end of resistor RR20 is grounded, and resistors RR19 and RR20 can play a role in current limiting. The cathode of diode RD2 is connected to the voltage-stabilized power supply, the anode of diode RD2 is connected to the gate of PMOS tube RQ3, and diode RD2 can play a role in preventing reverse connection. The two ends of resistor RR17 are connected to the gate and source of PMOS tube RQ3, resistor RR17 can play a role in current limiting, capacitor RC5 is connected in parallel with resistor RR17, and capacitor RC5 can perform filtering. When the control chip 1 turns on the NMOS tube RQ4 through the twenty-ninth pin, the source voltage of the PMOS tube RQ3 is higher than the gate voltage, the PMOS tube RQ3 is turned on, and the current of the regulated power supply can supply power to the second LED light source 33, and the second LED light source 33 is lit.

[0044] The second sampling circuit 32 includes: a resistor RR27, a resistor RR28 and a resistor RR29, wherein the resistor RR27 and the resistor RR29 are connected in series, one end of the resistor RR28 is connected to one end of the resistor RR29, the other end of the resistor RR29 is connected to the control chip 1 (the 30th pin), the other end of the resistor RR29 is grounded, and one end of the resistor RR27 is connected to the output end of the second LED light source 33. The current flowing through the second LED light source 33 can pass through the second sampling circuit 32, and the resistors RR27 and RR29 can play a voltage dividing role. The output voltage of the second LED light source 33 is sent to the control chip 1 after being divided by the second sampling circuit 32. The second LED light source 33 includes a plurality of LED lamp beads, which are connected in series. When an LED lamp bead in the second LED light source 33 is open-circuited, the output voltage of the second LED light source 33 is 0V, and when an LED lamp bead in the second LED light source 33 is short-circuited, the output voltage of the second LED light source 33 will be greater than that in normal operation. When the output voltage of the second LED light source 33 changes, the voltage division on the second sampling circuit 32 will also change accordingly. Therefore, the control chip 1 can determine whether the second LED light source 33 has a short circuit or open circuit fault by reading the voltage on the second sampling circuit 32.

[0045] That is to say, the present invention collects the output voltages of the first LED light source 23 and the second LED light source 33 respectively through the first sampling circuit 22 and the second sampling circuit 32 (because when the LED is short-circuited, the voltage at the fault point may exceed 5V. If the control chip 1 directly collects the output voltage of the LED light source, the control chip 1 may be damaged. Therefore, in addition to collecting the output voltage of the LED light source, the sampling circuit can also protect the control chip 1). The control chip 1 detects whether the output voltage of the LED light source changes to identify whether an open circuit or a short circuit occurs in the LED light source. In addition, the first sampling circuit 22 and the second sampling circuit 32 are both composed of resistors, and the cost of the resistors is only a few cents or a few dimes, while the cost of a driver chip suitable for car lights (such as E522.80) is more than ten yuan, and it needs to be purchased from abroad, which is not only expensive, but also not conducive to batch use. Therefore, the present invention replaces the driver chip with a "logic control circuit + sampling circuit", which can not only significantly reduce the total cost of the circuit, but also detect the situation where only a single LED lamp bead is short-circuited, which can further improve the accuracy of fault detection. In addition, the circuit of the present invention has only one control chip, and the rest are small components such as resistors and capacitors, which can reduce the occupied area, reduce the difficulty of layout and installation on the PCB board, and is also conducive to EMC testing.

[0046] The detection circuit of the present invention further includes: a first drive circuit 4 and a second drive circuit 5, wherein the first drive circuit 4 is connected to the output end of the first LED light source 23, and the second drive circuit 5 is connected to the output end of the second LED light source 33. Specifically, the first drive circuit 4 includes a plurality of resistors, and the second drive circuit 5 includes a plurality of resistors, and the brightness of the first LED light source 23 and the second LED light source 33 can be changed by adjusting the resistance values ​​of the first drive circuit 4 and the second drive circuit 5.

[0047] The present invention also provides a method for using a vehicle lamp fault detection circuit, comprising the following steps:

[0048] S1 . The control chip 1 lights up the first LED light source 23 by controlling the first logic control circuit 21 ; the control chip 1 lights up the second LED light source 33 by controlling the second logic control circuit 31 .

[0049] S2 . Collect the output voltage value V1 of the first LED light source 23 through the first sampling circuit 22 ; collect the output voltage value V3 of the second LED light source 33 through the second sampling circuit 32 .

[0050] S3, the control chip 1 reads the divided voltage V2 of the first sampling circuit 22 and the divided voltage V4 of the second sampling circuit 32 in real time; the control chip 1 converts the divided voltages V2 and V4 into digital signals ADC V2 and ADC V4 , the control chip 1 converts the digital signal ADC V2 and ADC V4 The digital value is compared with the set digital value threshold range to determine whether the first LED light source 23 and the second LED light source 33 are faulty.

[0051] Assuming that the working voltage of a single LED lamp bead is V_F, and the voltage of the voltage regulator is DCout, the output voltages V1 and V3 can be expressed as: V1 = DCout-0.1-n*V_F, V3 = DCout-0.1-m*V_F, where 0.1 represents the voltage drop of the MOS tube, and n and m represent the number of LED lamp beads. For example, taking the first LED light source 23 as a fog lamp as an example, the first LED light source 23 includes two LED lamp beads, and the normal operating voltage range of a single LED lamp bead is 1.9V≤V_F≤2.8V, DCout=8.3V, then V1=8.3-0.1-2*V_F, that is, the theoretical output voltage range of the first LED light source 23 in normal state is 2.6V≤V1≤4.4V. When a lamp bead in the first LED light source 23 is open circuit, the theoretical output voltage V1=0V. When one of the first LED light sources 23 is short-circuited (i.e., the resistance of the lamp bead becomes 0), the theoretical output voltage is 5.4V≤V1≤6.3V. When two of the first LED light sources 23 are short-circuited, the theoretical output voltage is V1=8.2V. Therefore, the voltage threshold ranges of the first LED light source 23 and the second LED light source 33 in the normal, short-circuited, and open-circuited states can be set according to the changes in the output voltages V1 and V3 of the LED lamp beads when they are in normal operation, short-circuited, and open-circuited. For example, the voltage threshold range of the first LED light source 23 in the normal state can be set to 1.1V≤V1≤5V, the voltage threshold range of the first LED light source 23 in the open-circuited state can be set to 0V≤V1<1V, and the voltage threshold range of the first LED light source 23 in the short-circuited state can be set to V1>5.1V. In other words, when setting the threshold range, it can be appropriately expanded on the basis of the theoretical value to prevent missed detection.

[0052] The calculation formula of the divided voltage V2 is:

[0053] The calculation formula of the divided voltage V4 is: For example, the resistance of resistor FR30 is 33KΩ, the resistance of resistor FR32 is 100KΩ, and the resistance of resistor FR31 is 1KΩ, then V2≈0.75V1. For example, the resistance of resistor RR27 is 15KΩ, the resistance of resistor RR28 is 1KΩ, and the resistance of resistor RR29 is 100KΩ, then V4≈0.87V3. The calculation formula for converting voltage into digital signal is: Among them, 5 represents the reference voltage of the built-in ADC of the control chip 1, and α represents the number of bits of the built-in ADC of the control chip 1. For example, if the number of bits of the built-in ADC of the control chip 1 is 12 bits, the voltage values ​​V2 and V4 can be converted into digital quantities as follows:

[0054] ADC V2 =(0.75V1*4096) / 5,ADC V4=(0.87V3*4096) / 5,

[0055] Therefore, the digital threshold range can be obtained according to the endpoints of the set voltage threshold range. Please refer to Table 1. Taking the first LED light source 23 as an example, the endpoints of the V1 voltage threshold range are 1V, 1.1V, 5V, and 5.1V. The endpoints of the V2 voltage threshold range can be calculated, and then the endpoint values ​​of V2 are converted into digital quantities. For the convenience of judgment, the calculated digital quantity is rounded to an integer to obtain the digital threshold range of the first LED light source 23 in normal, open circuit, and short circuit states. The control chip 1 reads the real-time divided voltages V2 and V4, and then converts the voltage value into a real-time digital quantity, determines which range the real-time digital quantity falls into, and determines the current working state of the first LED light source 23.

[0056] Table 1

[0057]

[0058] In summary, the present invention adopts the method of "control chip + logic control circuit + sampling circuit" to realize the driving and detection of LED light source, eliminating the driver chip, which can not only save 70% to 80% of the cost, but also detect the fault of only a single LED lamp bead short circuit, which can further improve the detection accuracy and reliability. In addition, the logic control circuit and sampling resistor use micro components such as resistors, capacitors, MOS tubes, etc., which occupy a small area, can reduce the difficulty of PCB board layout and installation, and are also conducive to EMC testing.

[0059] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A vehicle lamp fault detection circuit, characterized in that: include: A control chip (1), and A first detection module, comprising a first logic control circuit (21), a first sampling circuit (22) and a first LED light source (23), wherein the first logic control circuit (21) and the first sampling circuit (22) are both connected to the control chip (1), an input end of the first LED light source (23) is connected to the first logic control circuit (21), and an output end of the first LED light source (23) is connected to the first sampling circuit (22); A second detection module, comprising a second logic control circuit (31), a second sampling circuit (32) and a second LED light source (33), wherein the second logic control circuit (31) and the second sampling circuit (32) are both connected to the control chip (1), an input end of the second LED light source (33) is connected to the second logic control circuit (31), and an output end of the second LED light source (33) is connected to the second sampling circuit (32); The first logic control circuit (21) comprises: an NMOS tube FQ4, a PMOS tube FQ3, and a resistor FR18, wherein the gate of the NMOS tube FQ4 is connected to the control chip (1), the source of the NMOS tube FQ4 is grounded, the drain of the NMOS tube FQ4 is connected to the gate of the PMOS tube FQ3 via the resistor FR18, the source of the PMOS tube FQ3 is connected to a regulated power supply, and the drain of the PMOS tube FQ3 is connected to an input end of a first LED light source (23); The first sampling circuit (22) comprises: a resistor FR30, a resistor FR31 and a resistor FR32, the resistor FR30 and the resistor FR32 are connected in series, one end of the resistor FR31 is connected to one end of the resistor FR32, the other end of the resistor FR31 is connected to the control chip (1), the other end of the resistor FR32 is grounded, and one end of the resistor FR30 is connected to the output end of the first LED light source (23); The second logic control circuit (31) comprises: an NMOS tube RQ4, a PMOS tube RQ3, and a resistor RR18, wherein the gate of the NMOS tube RQ4 is connected to the control chip (1), the source of the NMOS tube RQ4 is grounded, the drain of the NMOS tube RQ4 is connected to the gate of the PMOS tube RQ3 via the resistor RR18, the source of the PMOS tube RQ3 is connected to a regulated power supply, and the drain of the PMOS tube RQ3 is connected to the input end of a second LED light source (33); The second sampling circuit (32) comprises: a resistor RR27, a resistor RR28 and a resistor RR29, wherein the resistor RR27 and the resistor RR29 are connected in series, one end of the resistor RR28 is connected to one end of the resistor RR29, the other end of the resistor RR29 is connected to the control chip (1), the other end of the resistor RR29 is grounded, and one end of the resistor RR27 is connected to the output end of the second LED light source (33); The first LED light source (23) and the second LED light source (33) both comprise a plurality of LED lamp beads, and the plurality of LED lamp beads are connected in series.

2. The vehicle lamp fault detection circuit according to claim 1, characterized in that: Also includes: A first drive circuit (4) and a second drive circuit (5), wherein the first drive circuit (4) is connected to an output end of the first LED light source (23), and the second drive circuit (5) is connected to an output end of the second LED light source (33).

3. A method for using the vehicle light fault detection circuit according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, the control chip (1) lights up the first LED light source (23) by controlling the first logic control circuit (21); the control chip (1) lights up the second LED light source (33) by controlling the second logic control circuit (31); S2, collecting the output voltage value V1 of the first LED light source (23) through a first sampling circuit (22); collecting an output voltage value V3 of the second LED light source (33) through a second sampling circuit (32); S3, the control chip (1) reads the divided voltage V2 of the first sampling circuit (22) and the divided voltage V4 of the second sampling circuit (32) in real time; the control chip (1) converts the divided voltages V2 and V4 into digital signals ADC V2 and ADC V4 The control chip (1) converts the digital signal ADC V2 and ADC V4 respectively comparing with a set digital value threshold range to determine whether the first LED light source (23) and the second LED light source (33) are faulty; Assume that the working voltage of a single LED lamp bead is V_F and the voltage of the regulated power supply is DC out , then the output voltages V1 and V3 can be expressed as: V1=DC out -0.1-n*V_F, V3=DC out -0.1-m*V_F, where 0.1 represents the voltage drop of the MOS tube, and n and m represent the number of LED beads; According to the changes in the output voltages V1 and V3 of the LED lamp beads when they are in normal operation, short circuit, and open circuit, the voltage threshold ranges of the first LED light source (23) and the second LED light source (33) when they are in normal, short circuit, and open circuit states are set; and the voltage threshold ranges are then converted into digital threshold ranges; The calculation formula for converting voltage into digital signal is: ， Here, 5 represents the reference voltage of the built-in ADC of the control chip (1), and α represents the number of bits of the built-in ADC of the control chip (1).

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