Let the car LED lighting without dead corners, LED drive comprehensive evolution

LED lighting is widely used in the automotive industry because of its characteristics of high brightness, low energy consumption, long life and fast response. LED headlights, daytime running lights, brake lights and turn signals have become standard on many models. At the same time, with the progress of intelligent driving technology, automotive LED lighting solutions are also developing in the direction of intelligence. For example, the adaptive headlight system can automatically adjust the beam distribution according to road conditions and speed, thus significantly improving driving safety; The interior LED lighting supports a variety of mode switching, creating a more comfortable ride experience for passengers.

The realization of all these functions is inseparable from the excellent performance of the LED driver. It ensures the stable operation of the LED light source and extends its service life by precisely controlling the current and voltage. In addition, LED drivers can also adjust the light intensity according to different application scenarios to meet diverse needs. Most importantly, efficient LED drivers help reduce energy consumption, in line with the trend of green energy saving.

Become a versatile car LED driver

With the continuous popularization of automotive LED technology, automotive LED drivers have evolved a variety of characteristics for the needs of various lighting scenes. These features not only reflect the maturity and progress of automotive LED driver technology, but also provide more abundant and flexible options for automotive lighting systems.

Highly efficient LED drivers not only provide higher brightness output, but also significantly reduce energy consumption, thereby improving the overall energy efficiency of the vehicle. Intelligent and programmable features enable LED drivers to automatically adjust the beam distribution according to road and environmental conditions, thereby improving driving comfort and safety, and allowing users to personalize Settings through digital communication interfaces such as I2C and SPI. In addition, the use of advanced materials and design technology, so that LED drivers have high reliability and long life characteristics, can work stably under a variety of harsh environmental conditions, effectively reducing maintenance costs.

Fast response capabilities and high frequency PWM control technology provide smoother dimming, reduced flickering, improved visual comfort, and rapid delivery of the required lighting level in an emergency. This technology is essential to improve the driver's attention and reaction speed, especially at night or in low visibility conditions.

Finally, the trend toward miniaturization and integration also allows LED drivers to be more easily integrated into various components of the vehicle, reducing the number of components and improving the overall reliability and performance of the system. This design optimization not only helps to reduce the weight of the vehicle, but also helps to simplify the manufacturing process and reduce costs.

Powerful exterior lighting

Headlights include low light, high beam light, day running light, wide light, turn signal light and fog light. Because the total power of the system is very large, and it integrates many functions, it needs more heat dissipation, and the design is relatively complex.

Matrix/pixel headlights are the new favorite in headlights, through hundreds or even thousands of tiny LED lamp beads to form a matrix or pixel array, to achieve precise control and adjustment of the lighting area. This design allows the headlights to intelligently adjust the shape, size and brightness of the beam according to actual road conditions and driving needs. The pixel is an LED light bead in the LED array, and each pixel has an area illuminated by the beam, which can be adapted to the driving intention and the traffic environment to improve safety. Its modular design can be adapted to any architecture.

Matrix LED by the switch type LED driver chip to provide high-power output to drive the LED lamp beads, with the matrix management chip to achieve a single LED (single pixel) independent on-off control. For example, onsemi's NCV78702 and NCV78723(dual-channel step-down), together with the pixel light control chip, form a complete solution that can drive multiple strings of LED lights up to 60V.

Among them, the NCV78702 is a single-chip high-efficiency boost converter for LED drives, designed for automotive headlight applications such as high beams, high beams, DRL (daytime running lights), turn indicators, fog lights, static turning, etc. It includes a current mode voltage boost controller with minimal external components and a customizable output voltage. The two NCV78702 can be combined to become a polyphase booster circuit to further optimize the filter effect of the booster and reduce the BOM cost.

The NCV78723 can drive 2 strings of LED lights up to 60V. It includes 2 independent current regulators for diagnostic functions required for LED strings and automotive headlights, the chip does not require any external detection resistance to regulate the buck current, and the output current can be customized. When more than 2 LED channels are required on a module, 2, 3 or more NCV78723s can be combined.

The rear light is used to remind the surrounding vehicles and pedestrians that the driving intention of the car is about to occur, including turning, braking, parking, etc. At the same time, various shapes on the car body can also be used as a sign of the identity of the car, and the working current is generally less than 100mA. Rear combination lights have these high-level functions: enhanced parking lights, taillights, turn signals are dynamic segmental light signals, but also to achieve the beam to create brand, welcome, animation and other effects, can drive a single string, multiple string LED beads, higher energy efficiency, less loss, and includes safety diagnosis function.

The NCV7683 consists of eight 100mA linear programmable constant current sources for LED-based rear-rear combination light regulation and control and flashing functions in automotive applications. The system design with NCV7683 enables two cutoff programming levels (100% duty cycle) and tail lighting (programmable duty cycle), as well as optional external PWM control. LED brightness can be easily programmed with two external resistors (cut-off programmed for absolute current value and tail programmed for duty cycle). The use of optional external ballast FETs enables power distribution on designs that require high currents. The rollback power limit reduces the drive current under overvoltage conditions. This is most useful for low-power applications that do not use external FETs.

Flexible, gorgeous interior lighting

Because the LED has great advantages in color temperature, color rendering index, brightness and so on, it is very suitable for short time use in the car, common instrument lights, step lights, door lights, suitcase lights, reading lights, ceiling lights and so on. In addition, LED can be used to characterize the vehicle status, such as whether the door is closed can be reflected by LED lights. At the same time, another outstanding advantage of using LED lights in the interior lighting system is that it can reduce the interference to the driver's line of sight, and thus effectively reduce the driver's glare.

On Semiconductor offers a wide range of discrete and integrated solutions to meet the needs of a wide range of lighting applications. These include both simple solutions such as the double-ended constant current Stabilizer (CCR), an economical but robust device that provides an effective current regulation solution for cost-sensitive automotive LED lighting; Some of the more sophisticated solutions include LIN RGB LED drivers, which combine a LIN transceiver with an RGB LED driver and memory to form a single chip RGB driver for monitoring multi-color LED applications.

The NSI45020J Adjustable Constant Current Stabilizer (CCR) is a simple, economical and durable device that provides a cost-effective solution for regulating current in leds (similar to a constant current diode CCD). The CCR is based on self-biased transistor (SBT) technology to regulate current over a wide voltage range. It uses a negative temperature coefficient to protect the LED from thermal collapse at extreme voltages and currents.

RGB and white leds complement each other, and their development is driven by the drive to further personalize vehicles for use as programmable interior light sources, including area lighting such as dashboard, center console, navigation/audio, and special effects applications such as atmosphere lights. The NCV7430 is a single-chip RGB driver for specialized multi-color LED applications. The RGB LED driver includes a LIN interface (slave interface) for LED color and chromaticity parameterization programming.

The device receives instructions via the LIN bus and then drives the LED alone. NCV7430 acts as a slave node on the LIN bus, and the master node can request specific status information (parameter values and error flags). The LIN address of the NCV7430 can be programmed in the device's internal memory. One of the features of the device is 24-bit true color, which enables the module to output 16 million different colors via the LIN command, which is used to create a personalized interior atmosphere in the car.

Conclusion

On Semiconductor offers a comprehensive range of semiconductor solutions for applications such as headlights, matrix/pixel lights and rear combination lights. These solutions not only offer high energy efficiency, high integration and excellent reliability, but also achieve excellent scalability and flexibility thanks to the platform-based design concept. This undoubtedly brings great convenience to designers, helping them to travel the road of innovation, while simplifying and speeding up the product development process. In addition, ON's smart power supply combined with advanced intelligent perception technology has laid a solid foundation for improving road traffic safety.