Low cost LED driver circuit with diagnostic function

Abstract

The utility model relates to the field of vehicle display, concretely refers to a low -cost LED drive circuit with diagnostic function. The low -cost LED drive circuit with diagnostic function includes decoding module, interface conversion module, drive module and LED pilot lamp that connect gradually. Among them, decoding module will control end transmission's multichannel low -speed parallel signal conversion into high -speed serial signal transmission and give interface conversion module, and signal again conversion into original control signal output and give drive module through interface conversion module, and drive module carries out control to LED pilot lamp according to the control signal of input. The utility model adopts interface chip to guarantee the stable drive of LED through the reasonable design of circuit, still integrates the fault diagnosis function, ensures when the fault can produce alarm signal in time, thereby improves the security of system, and simultaneously still effectively reduced the whole vehicle display module manufacturing and later period maintenance cost, makes this scheme more market competitiveness.

Description

Technical Field

[0001] This utility model relates to the field of vehicle display, specifically to a low-cost LED driver circuit with diagnostic function. Background Technology

[0002] In the field of automotive displays, indicator lights are needed to inform drivers of the display's operational status and enhance safety, in order to meet safety requirements. These indicator lights typically require a microcontroller (MCU) for control, performing functions such as display, driving, and monitoring for open or short circuits. While existing LED driver solutions offer good performance and reliability, they also suffer from high cost and system complexity.

[0003] In recent years, automotive applications have become extremely cost-sensitive, especially in mid-to-low-end models, where excessively high driver costs can affect the overall market competitiveness of the vehicle. Utility Model Content

[0004] To address the aforementioned problems, the purpose of this invention is to provide a low-cost LED driver circuit to replace the existing MCU-controlled driver circuit for driving and safety monitoring of LEDs.

[0005] The low-cost LED driver circuit with diagnostic function includes: an interface conversion module and a driver module, an LED indicator connected to the output terminal of the driver module, the interface conversion module being connected to the current monitoring terminal of the driver module via a first pin, to the error reporting terminal of the driver module via a second pin, and to the enable terminal of the driver module via a third pin; the current monitoring terminal of the driver module is grounded through a first resistor.

[0006] Specifically, the output of the drive module is connected to an LED indicator via a second resistor.

[0007] Specifically, the maximum current setting terminal of the drive module is grounded through a third resistor, providing a short-circuit monitoring comparison signal to the second pin of the interface conversion chip.

[0008] Specifically, the low-cost LED driver circuit with diagnostic function also includes a decoding module connected to the input of the interface conversion module.

[0009] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0010] The driving circuit described in this utility model uses an interface chip to replace the MCU chip. The interface chip, through reasonable circuit design, not only ensures stable driving of the LED lights, but also integrates fault diagnosis functions. The organic combination of the diagnostic function and the LED driving circuit ensures that alarm signals can be generated in a timely manner when a fault occurs, thereby improving the functional safety of the system. At the same time, it also effectively reduces the manufacturing and subsequent maintenance costs of the vehicle display module, making the solution more competitive in the market. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the driving circuit embodiment of the present invention. Detailed Implementation

[0012] To facilitate understanding of this invention, a more comprehensive description will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the invention. However, this invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0013] like Figure 1 As shown, the low-cost LED driver circuit with diagnostic function of this utility model includes a decoding module, an interface conversion module, a driver module, and an LED indicator connected in sequence. The decoding module converts multiple low-speed parallel signals sent from the control terminal into high-speed serial signals and transmits them to the interface conversion module. The interface conversion module then converts the signals back into the original control signals and outputs them to the driver module. The driver module controls the LED indicator according to the input control signals. The LED driver circuit also includes a power supply module that provides power for the normal operation of each module.

[0014] As an example, such as Figure 1 As shown, the interface conversion module can use an I / O interface chip, such as the TCA9539QPWRQ1 I / O interface chip, and the driver module can use the TPS2H000B LED driver chip. The I / O interface chip converts the I2C signal transmitted from the decoding module (i.e., the deserializer) and outputs it through its interface. The I / O interface chip is connected to the driver module current monitoring terminal I_DET through its first pin, to the driver module error reporting terminal Fault through its second pin, and to the driver module enable terminal Enable through its third pin. The driver module current monitoring terminal I_DET is grounded through resistor R1. The driver module maximum current setting terminal is grounded through resistor R3. The driver module's I_MAX pin is used to set the maximum value of the current output VOUT. Once the VOUT output exceeds this maximum value, the Fault pin will report an error (output low level), thus monitoring for short circuits. The driver module output terminal VOUT is grounded through a series resistor R2 and an LED indicator, controlling the LED indicator to display different brightness changes according to the display status.

[0015] The LED indicator lights in a vehicle display module typically have four states: LED ON, LED OFF, LED SHORT, and LED OPEN. Since the I / O ports in the interface conversion module can generally recognize a low level of 30% of the LED supply voltage (VDD*0.3=0.99V) and a high level of 70% (VDD*0.7=2.31V), by setting the driver module's operating voltage VDD=3.3V and appropriately configuring the resistance values ​​of resistors R3 and R1, the above four LED states can be monitored. The corresponding pin levels for these four states are shown in the table below (1 for high level, 0 for low level, X for no signal):

[0016]

[0017] As can be seen from the truth table above, using three pins to determine the four states of an LED is sufficient to monitor the LED's status. When the LED is normally on (LED ON), the logic level of the three pins is 1X1 (Enable / Fault / I_DET); when the LED is normally off (LED OFF), the logic level of the three pins is 0X0 (Enable / Fault / I_DET); when the LED is short-circuited (LED SHORT), the logic level of the three pins is 10X (Enable / Fault / I_DET); and when the LED is open-circuited (LED OPEN), the logic level of the three pins is 1X0 (Enable / Fault / I_DET). In practice, the deserializer uses IIC to read the status of four pins (enable / fault / I_DET) of the I / O interface chip, monitors the level of these pins, and then determines the status of the LED according to the truth table mentioned above. For example, if Enable = high and I_DET = low, then the LED is determined to be PEN. This enables real-time monitoring of the LED's working status. This diagnostic function can not only identify and report faults in a timely manner, but also meet the requirements of functional safety standards such as ISO 26262, thereby improving the functional safety of the entire vehicle.

[0018] This invention optimizes the design of the LED driver circuit, reduces the use of high-cost components, and simplifies the system architecture, thereby significantly reducing costs while ensuring performance, making it more suitable for large-scale applications, especially for cost-sensitive mid-to-low-end models.

[0019] For any part of this utility model not specifically described, common methods or common knowledge in the field can be used, and will not be elaborated here.

[0020] The above description of the disclosed embodiments is intended to satisfy the requirement of clarity and completeness of the specification, enabling those skilled in the art to implement the present invention based on this description. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-cost LED driver circuit with diagnostic function, characterized in that, It includes an interface conversion module, a driver module, and an LED indicator connected to the output terminal of the driver module. The interface conversion module is connected to the current monitoring terminal of the driver module through a first pin, to the error reporting terminal of the driver module through a second pin, and to the enable terminal of the driver module through a third pin. The current monitoring terminal of the driver module is grounded through a first resistor.

2. The low-cost LED driver circuit with diagnostic function according to claim 1, characterized in that, The output of the drive module is connected to an LED indicator via a second resistor.

3. The low-cost LED driver circuit with diagnostic function according to claim 1, characterized in that, The maximum current setting terminal of the drive module is grounded through a third resistor, providing a short-circuit monitoring comparison signal for the second pin of the interface conversion chip.

4. The low-cost LED driver circuit with diagnostic function according to claim 1, characterized in that, It also includes a decoding module connected to the input of the interface conversion module.

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