A high-reliability indicator light driving and detecting method, circuit and system

Abstract

The application discloses a kind of high reliability pilot lamp driving and detection method, circuit and system.Method includes: receiving first voltage domain control signal by power electronic switch chip and outputting second voltage domain driving voltage;First voltage difference voltage and second voltage difference voltage of negative electrode of pilot lamp anode are collected;According to voltage difference, real-time working voltage and current are calculated;According to two voltage difference voltage, short-circuit fault is judged according to fault flag or anode voltage;According to real-time voltage, dynamic adjustment PWM duty cycle is realized to achieve constant brightness.Circuit includes power supply circuit, control circuit including power electronic switch chip, positive and negative electrode voltage monitoring circuit and fault feedback circuit.The application is compatible with 3.3V control signal and 8~18V driving voltage, working temperature-40℃~+125℃, through voltage monitoring, replace Hall current sensor to realize fault diagnosis and brightness adjustment, low in cost, high in reliability, applicable to vehicle parking / brake pilot lamp.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuits and vehicle control technology, specifically relating to a highly reliable driving and detection method, circuit and system for vehicle parking / brake indicator lights. Background Technology

[0002] In vehicle electronic systems, parking indicator lights and brake indicator lights are directly related to driving safety and personal safety, requiring extremely high reliability and functional integrity. Existing indicator light drive solutions have the following technical shortcomings: Poor voltage compatibility: Most solutions cannot simultaneously support low-voltage (e.g., 3.3V) MCU control signals and high-voltage (e.g., 8V~18V) indicator light drive voltages, requiring additional level conversion circuits, which increases system complexity and cost.

[0003] Narrow operating temperature range: Ordinary consumer-grade electronic components cannot operate stably within a wide temperature range of -40℃ to +125℃, which cannot meet the environmental requirements of automotive-grade applications.

[0004] High fault detection costs: To detect open and short circuits in indicator lights, existing technologies typically use Hall effect current sensors for current monitoring. While this approach offers high accuracy, the sensors themselves are expensive and require additional signal conditioning circuitry, which is detrimental to overall vehicle cost control.

[0005] Insufficient brightness stability: When the vehicle's power supply voltage fluctuates (such as when the engine starts and stops, causing a voltage drop), the traditional drive circuit cannot automatically adjust the brightness, resulting in changes in the brightness of the indicator light, which affects the user experience and warning effect.

[0006] Therefore, developing a highly reliable, wide-temperature and wide-pressure compatible, low-cost indicator light driver solution with comprehensive fault diagnosis capabilities is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] Purpose of the invention The purpose of this invention is to provide a highly reliable indicator light driving and detection method, circuit and system to solve the problems of incompatibility between control signals and driving voltage, narrow operating temperature range, high fault detection cost and insufficient brightness stability in the prior art.

[0008] Technical solution To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a highly reliable indicator light driving and detection method, comprising the following steps: Driving steps: The power electronic switch chip receives the control signal of the first voltage domain and outputs the driving voltage of the second voltage domain to the indicator light; wherein, the first voltage domain is 3.3V~5.0V and the second voltage domain is 8V~18V; Positive sampling step: Collect the first voltage divider voltage between the positive terminal of the indicator light and ground; Negative sampling step: Collect the second voltage divider voltage between the negative terminal of the indicator light and ground; Voltage / current calculation steps: Calculate the real-time operating voltage of the indicator light based on the difference between the first voltage divider and the second voltage divider and the preset voltage division ratio coefficient; and calculate the real-time operating current of the indicator light based on the real-time operating voltage and the resistance value of the current limiting resistor inside the indicator light. Troubleshooting steps: When the first voltage divider is not zero and the second voltage divider is approximately zero, it is determined that the indicator light has an open circuit fault. When both the first voltage divider and the second voltage divider are approximately zero, it is determined that the power electronic switch chip has an open circuit fault. When the power electronic switch chip outputs a fault flag signal, it is determined to be a short circuit, overcurrent, or overheating fault; Brightness adjustment steps: Based on the real-time operating voltage and the target brightness value, dynamically adjust the PWM duty cycle of the control signal to keep the average brightness of the indicator light constant.

[0009] Secondly, the present invention provides a highly reliable indicator light driving and detection circuit for implementing the above method, including: The power supply circuit is used to connect the input power supply and perform reverse connection protection and filtering. The control circuit includes a power electronic switch chip. The power input terminal of the power electronic switch chip is connected to the output terminal of the power supply circuit. Its enable terminal is used to receive the control signal output by the MCU, and its output terminal is used to output the drive voltage to the positive terminal of the indicator light. A positive voltage monitoring circuit is connected between the output terminal of the power electronic switch chip and ground to collect the first voltage divider voltage of the positive terminal of the indicator light to ground and output it to the MCU; The negative voltage monitoring circuit is connected between the negative terminal of the indicator light and ground. It is used to collect the second voltage divider voltage of the negative terminal of the indicator light to ground and output it to the MCU. The fault feedback circuit connects the fault flag pin of the power electronic switch chip to the MCU; The MCU executes the fault judgment step and brightness adjustment step based on the first voltage divider voltage, the second voltage divider voltage, and the state of the fault flag pin.

[0010] Furthermore, the power electronic switch chip operates at a temperature of -40℃ to +125℃, its enable terminal is compatible with control signals of 3.3V to 5.0V, and its output terminal is compatible with drive voltages of 8V to 18V.

[0011] Furthermore, the positive voltage monitoring circuit includes a first voltage divider resistor and a second voltage divider resistor connected in series, a first filter capacitor, and a first voltage clamping protection diode; the negative voltage monitoring circuit includes a third voltage divider resistor and a fourth voltage divider resistor connected in series, a current limiting resistor, a second filter capacitor, and a second voltage clamping protection diode.

[0012] Furthermore, the control circuit also includes a reverse diode group and a decoupling circuit connected to the enable terminal of the power electronic switch chip, as well as a short-circuit current regulating resistor connected to the current limiting pin of the power electronic switch chip.

[0013] Furthermore, an electrostatic discharge protection diode is connected in parallel at the indicator light input port, and the power supply circuit includes an input reverse connection protection diode.

[0014] Thirdly, the present invention provides a high-reliability indicator light control system, comprising: MCU, and the high-reliability indicator light driver and detection circuit as described in any of the preceding items; The MCU is configured as follows: The first voltage divider and the second voltage divider are obtained through the positive voltage monitoring circuit and the negative voltage monitoring circuit. The indicator light is judged to have an open circuit fault based on the combined voltage values ​​of the first and second voltage dividers. The level state of the fault flag pin is detected to determine whether a short circuit, overcurrent, or overtemperature fault has occurred. Based on the fluctuations in the input voltage, the duty cycle of the PWM signal output to the control circuit is adjusted to stabilize the brightness of the indicator light.

[0015] Furthermore, the MCU is also configured to output an alarm signal to the host computer when it is determined that an open circuit, short circuit, over-temperature, or over-current fault has occurred.

[0016] Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: Wide voltage compatibility and wide temperature range: It adopts industrial-grade or automotive-grade power electronic switch chips, which can be directly compatible with 3.3V~5.0V MCU control signals and 8V~18V indicator light drive voltages without the need for additional level conversion circuits; the operating temperature range reaches -40℃~+125℃, meeting various harsh environmental requirements.

[0017] Significant cost advantages: By acquiring the voltage divider through a positive and negative voltage monitoring circuit, and using an MCU to calculate the voltage difference across the indicator light and extrapolate the real-time current, this invention completely replaces the traditional Hall current sensor solution. The cost of a Hall sensor and its signal conditioning circuit typically ranges from several to tens of yuan, while this invention only requires a few resistors, capacitors, and diodes, reducing costs by approximately 80% or more.

[0018] Comprehensive fault diagnosis: Supports indicator light open circuit fault detection, short circuit fault detection and short circuit protection functions. The fault judgment logic is clear and reliable, realizing comprehensive fault monitoring.

[0019] Automatic brightness adjustment: By monitoring the indicator light's operating voltage in real time and dynamically adjusting the duty cycle of the PWM drive signal, the indicator light brightness can be kept constant when the input voltage fluctuates, improving user experience and warning effect.

[0020] High reliability design: The circuit integrates multiple protection measures such as reverse connection protection, electrostatic protection, voltage clamping protection, decoupling filtering, and short-circuit current limiting to ensure stable operation of the circuit in harsh electrical environments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a high-reliability indicator light driver and detection circuit according to an embodiment of the present invention. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] Example 1: Circuit Structure like Figure 1 As shown, the high-reliability indicator light driving and detection circuit of this embodiment includes the following parts: 1. Power supply circuit It consists of a reverse-connection protection diode D1 and input filter capacitors C1 and C2. The input power supply POWER is protected against reverse connection by D1, and then filtered by C1 and C2 to provide a stable power supply with correct polarity for subsequent circuits. The positive terminal of D1 is connected to POWER, and the negative terminal is connected to the VIN pin of U1.

[0024] 2. Control circuit The core is the power electronic switch chip U1. In this embodiment, an industrial-grade or automotive-grade high-reliability load switch chip is selected. The operating temperature range is -40℃ to +125℃. Its enable terminal EN / nFAULT is compatible with 3.3V to 5.0V logic levels, and the output terminal OUT supports 8V to 18V drive voltage.

[0025] U1's VIN pin is connected to the power supply circuit output; The EN / nFAULT pin receives the MCU control signal MCU_EN via the anti-reverse diode D5 and the current-limiting resistor R4; at the same time, the EN / nFAULT pin is also grounded via the decoupling resistor R6 and the capacitor C5 to eliminate high-frequency interference. The ILIM pin is grounded via resistor R5 and is used to set the short-circuit current protection threshold. The OUT pin is the drive voltage output terminal.

[0026] In addition, the EN / nFAULT pin is also connected to the MCU_FAULT pin via a reverse protection diode D6 to provide fault status feedback to the MCU (open-drain output, active low). The fault statuses represented by the MCU_FAULT pin include overcurrent protection OCP, overtemperature protection OTP, and short-circuit protection OSP.

[0027] 3. Positive voltage monitoring circuit It consists of voltage divider resistors R3 and R7, filter capacitor C6, and clamping diode D2. R3 and R7 are connected in series between the OUT pin of U1 and ground, and the midpoint voltage divider node outputs the ADC_LED+ signal. C6 is used to filter out high-frequency noise, and D2 clamps the ADC_LED+ voltage within the safe input range of the MCU (usually 3.3V or 5V).

[0028] 4. Negative voltage monitoring circuit The negative terminal of the indicator LED- first passes through the internal current-limiting resistor R1 (considered part of the external indicator in this circuit), then through the voltage divider resistor R2 to ground. The voltage divider node then passes through the current-limiting resistor R8 and the filter capacitor C7 in sequence to output the ADC_LED- signal. D3 is also a voltage clamping protection diode.

[0029] 5. Output filtering and electrostatic protection C4 is the output filter capacitor, connected between the OUT pin of U1 and ground; D4 is an electrostatic discharge protection diode, connected in parallel between the positive and negative terminals of the indicator light input port (between LED+ and LED-).

[0030] 6. Indicator light input port It includes a first terminal (LED+) and a second terminal (LED-), with an external indicator light connected between the two terminals. LED+ is directly connected to the OUT pin of U1, and LED- is connected to the input terminal of the negative voltage monitoring circuit.

[0031] Example 2: Fault Judgment Logic The MCU acquires two voltage signals via ADC_LED+ and ADC_LED-, and, in conjunction with the MCU_FAULT pin status, performs the following fault diagnosis: (1) Circuit break detection The voltage values ​​at both ends of the indicator light (LED+ and LED-) are obtained by monitoring the voltages of ADC_LED+ and ADC_LED-. The voltage values ​​of ADC_LED+ and ADC_LED- can be used to comprehensively determine whether an open circuit has occurred in the indicator light circuit.

[0032] When MCU_EN is active (high level, indicator light should be on): Normal operating conditions: LED+ is at high voltage (close to the driving voltage), not zero; LED- is at low voltage (the indicator light's normal current is 15mA, and the resistance of R2 is 100R, therefore the voltage of LED- is 1.5V, not zero).

[0033] Internal open circuit of indicator light: If ADC_LED+ (first voltage divider) is not zero, while ADC_LED- (second voltage divider) is approximately zero, it indicates that the power electronic switch chip is outputting voltage normally, but the negative terminal of the indicator light cannot form a current loop, which is determined to be an internal open circuit of the indicator light. Power electronic switch chip U1 open circuit: If both ADC_LED+ and ADC_LED- are approximately zero, it indicates that the power electronic switch chip has no voltage output, which is determined to be an open circuit in the power electronic switch chip (possible causes: chip damage, power supply loss or abnormal enable signal).

[0034] (2) Short circuit detection Short-circuit faults can be redundantly detected in two ways: Method 1 (Hardware Protection Feedback): When a short circuit occurs, if the current flowing through U1 exceeds the threshold set by ILIM, the internal protection circuit of U1 will activate, cutting off the output. Simultaneously, the EN / nFAULT pin will output a low level, which will pull the MCU_FAULT pin low via D6. The MCU will detect that MCU_FAULT is low and determine that a short circuit, overcurrent, or overheating fault has occurred.

[0035] Method 2 (Software-assisted judgment): If the MCU detects an abnormal drop in the ADC_LED+ voltage (e.g., below 30% of the normal value) and the MCU_EN is in an active state, it can also help determine a short circuit fault.

[0036] (3) Fault reporting Once an overcurrent, overheat, open circuit, or short circuit fault is detected, the MCU can send alarm information to the vehicle's instrument panel or host computer via the CAN / LIN bus or a dedicated fault line to prompt the driver to perform maintenance.

[0037] Example 3: Automatic Brightness Adjustment The brightness of the indicator light depends on the loop current I_LED: I_LED = (V_LED+ - V_d) / (R1 + R2) Where: V_LED+ is the output voltage of U1; V_d is the on-state voltage drop of the LED indicator; R1 is the current-limiting resistor for the LED indicator; R2 is the current-limiting resistor for the circuit; R1 and R2 are fixed values, and Vd is also a constant under a fixed current.

[0038] When the power supply voltage fluctuates, the voltage of V_LED+ changes accordingly. By adjusting the duty cycle of the PWM, the average voltage of V_LED+ is kept constant, and the control loop current is kept constant, thereby stabilizing the brightness of the indicator light.

[0039] The MCU calculates the actual voltage across the indicator light in real time using ADC_LED+ and ADC_LED-. V_LED = (ADC_LED+ × K1) - (ADC_LED- × K2) Where K1 and K2 are the voltage division ratio coefficients of the positive and negative voltage divider circuits, respectively.

[0040] When the MCU detects a fluctuation in the input voltage POWER (e.g., a drop from 12V to 9V), V_LED decreases accordingly. To maintain a constant indicator brightness, the MCU dynamically adjusts the PWM duty cycle of the MCU_EN signal based on the deviation between the measured value of V_LED and the voltage value required for the target brightness: increasing the duty cycle when the voltage decreases and decreasing the duty cycle when the voltage increases.

[0041] Since the brightness of an indicator light is proportional to its average power, and the average power is linearly related to the PWM duty cycle, brightness stability can be achieved through closed-loop adjustment.

[0042] Example 4: Technical Effects of Replacing Hall Current Sensors In traditional solutions, a Hall current sensor needs to be connected in series in the circuit to detect the indicator light current to determine the fault. The Hall sensor outputs a weak differential signal, which requires a dedicated signal conditioning circuit (instrumentation amplifier, reference source, etc.), resulting in high overall cost. In addition, the sensor itself is relatively large, which is not conducive to PCB layout.

[0043] This invention acquires the voltage across the indicator light using a positive and negative voltage monitoring circuit, calculates the voltage difference using an MCU, and then divides it by the known value of the current-limiting resistor R1 inside the indicator light to obtain the real-time current. I_LED=(V_LED+ - V_d) / (R1 + R2) This solution eliminates the need for any current sensors, relying solely on existing voltage sampling resistors and the ADC function of the MCU to achieve real-time current monitoring, reducing costs by over 80% and without occupying additional PCB area.

[0044] Industrial applicability The highly reliable indicator light driving and detection method, circuit, and system of this invention employ industrial-grade or automotive-grade power electronic switching chips in conjunction with positive and negative voltage monitoring circuits. This achieves wide voltage compatibility (3.3V control / 8~18V drive), wide temperature range operation (-40℃~+125℃), sensorless current detection and fault diagnosis, and automatic brightness adjustment. This invention features a simple structure, low cost, and high reliability, making it particularly suitable for applications with stringent safety and environmental adaptability requirements, such as vehicle parking indicator lights and brake indicator lights. It possesses excellent industrial practicality and market promotion value.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various improvements, equivalent substitutions, modifications, and refinements can be made without departing from the spirit and principle of the present invention, and these improvements, equivalent substitutions, modifications, and refinements should also be considered within the scope of protection of the present invention.

Claims

1. A highly reliable indicator light driving and detection method, characterized in that, include: Driving steps: Receive the control signal of the first voltage domain (MCU_EN) through the power electronic switch chip, and output the driving voltage of the second voltage domain (8V~18V) to the indicator light; Positive sampling step: Collect the first voltage divider voltage (ADC_LED+) of the positive terminal of the indicator light to ground; Negative sampling step: Collect the second voltage divider voltage (ADC_LED-) of the negative terminal of the indicator light to ground; Current / voltage calculation steps: Calculate the real-time operating voltage and real-time operating current of the indicator light based on the difference between the first voltage divider and the second voltage divider. Troubleshooting steps: When the first voltage divider is not zero and the second voltage divider is approximately zero, it is determined that the indicator light has an open circuit fault. When both the first voltage divider and the second voltage divider are approximately zero, it is determined that the power electronic switch chip has an open circuit fault. When the power electronic switch chip outputs a fault flag signal, it is determined to be a short circuit, overcurrent, or overheating fault; Brightness adjustment steps: Based on the real-time operating voltage and the target brightness value, dynamically adjust the PWM duty cycle of the control signal.

2. A highly reliable indicator light driving and detection circuit, characterized in that, To implement the method of claim 1, the method comprises: The power supply circuit is used to connect the input power supply and to provide reverse connection protection and filtering. The control circuit includes a power electronic switch chip (U1), whose enable terminal receives MCU control signals and whose output terminal is connected to the positive terminal of an indicator light. A positive monitoring circuit is connected between the output terminal and ground, and outputs the first voltage divider to the MCU; The negative monitoring circuit is connected between the negative terminal of the indicator light and ground, and outputs the second voltage divider to the MCU; The fault feedback circuit connects the fault flag pin of the power electronic switch chip to the MCU; The MCU executes the fault judgment step and brightness adjustment step based on the first voltage divider voltage, the second voltage divider voltage, and the status of the fault flag pin.

3. The circuit according to claim 2, characterized in that, The power electronic switch chip (U1) operates at a temperature of -40℃ to +125℃. Its enable terminal is compatible with control signals of 3.3V to 5.0V, and its output terminal is compatible with drive voltages of 8V to 18V.

4. The circuit according to claim 2, characterized in that, The positive monitoring circuit includes a first voltage divider resistor (R3) and a second voltage divider resistor (R7) connected in series, a first filter capacitor (C6) and a first clamping diode (D2); the negative monitoring circuit includes a third voltage divider resistor (R1) and a fourth voltage divider resistor (R2) connected in series, a current limiting resistor (R8), a second filter capacitor (C7) and a second clamping diode (D3).

5. The circuit according to claim 2, characterized in that, The control circuit also includes a group of anti-reverse diodes (D5, D6), a decoupling circuit (R6, C5), and a short-circuit current regulating resistor (R5) connected to the enable terminal of the power electronic switch chip (U1).

6. The circuit according to claim 2, characterized in that, An electrostatic discharge protection diode (D4) is connected in parallel at the indicator light input port, and the power supply circuit includes an input reverse connection protection diode (D1).

7. A high-reliability indicator light control system, characterized in that, include: MCU, and the high-reliability indicator light driver and detection circuit as described in any one of claims 2 to 6; The MCU is configured as follows: The first voltage divider and the second voltage divider are obtained through the positive and negative monitoring circuits. The indicator light is judged to be open-circuited based on the combined voltage values ​​of the first and second voltage dividers. The level state of the fault flag pin is detected to determine whether a short circuit, overcurrent, or overtemperature fault has occurred. Based on the input voltage fluctuations, the duty cycle of the PWM signal output to the control circuit is adjusted to stabilize the indicator light brightness.

8. The system according to claim 7, characterized in that, The MCU is also configured to output an alarm signal to the host computer when it detects an open circuit, short circuit, over-temperature, or over-current fault.

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