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LED lighting has been widely used in the automotive industry due to its high brightness, low energy consumption, long life and fast response. LED headlights, daytime running lights, brake lights and turn signals have become standard features on many models. With the advancement of intelligent driving technology, automotive LED lighting solutions are also developing in an intelligent direction. For example, the adaptive headlight system can automatically adjust the beam distribution according to road conditions and vehicle speed, thereby significantly improving driving safety; while the in-car LED lighting supports multiple mode switching to create a more comfortable ride experience for passengers.
The realization of all these functions is inseparable from the LED driver with excellent performance. It ensures the stable operation of the LED light source and extends its service life by accurately controlling current and voltage. In addition, the LED driver can also adjust the light intensity according to different application scenarios to meet diverse needs. Most importantly, efficient LED drivers help reduce energy consumption and are in line with the trend of green energy saving.
The all-rounder role of automotive LED drivers
With the continuous popularization of automotive LED technology, automotive LED drivers have evolved a variety of characteristics to meet the needs of various lighting scenarios. These characteristics not only reflect the maturity and progress of automotive LED driver technology, but also provide richer and more flexible options for automotive lighting systems.
High-efficiency LED drivers not only provide higher brightness output, but also significantly reduce energy consumption, thus improving the overall energy efficiency of the vehicle. The intelligence and programmability features allow the LED driver to automatically adjust the beam distribution according to road and environmental conditions, thereby improving driving comfort and safety, and allowing users to perform personalized settings through digital communication interfaces such as I2C and SPI. In addition, the use of advanced materials and design technology enables the LED driver to have high reliability and long life, and can work stably under various harsh environmental conditions, effectively reducing maintenance costs.
Fast response capability and high-frequency PWM control technology provide smoother dimming effect, reduce flicker phenomenon, improve visual comfort, and quickly provide the required lighting level in emergency situations. This technology is critical to improving driver attention and reaction times, especially at night or in low-visibility conditions.
Finally, the trend of miniaturization and integration also makes it easier for LED drivers to be integrated into various components of vehicles, reducing the number of components and improving the overall reliability and performance of the system. This design optimization not only helps reduce vehicle weight, but also helps simplify the manufacturing process and reduce costs.
Powerful performance for exterior lighting
Headlights include low beam, high beam, daytime running lights, width lights, turn signals and fog lights. Since the total power of the system is very large and it integrates many functions, it requires more heat dissipation and the design is relatively complex.
Matrix/pixel headlights are the new favorite among headlights. They use hundreds or even thousands of tiny LED 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 lamp bead in the LED array. Each pixel has an area illuminated by a beam, which can adapt to driving intentions and traffic environment to improve safety. Its modular design adapts to any architecture.
Matrix LED uses a switch-type LED driver chip to provide high-power output to drive the LED lamp beads, and cooperates with the matrix management chip to achieve independent on-off control of a single LED (single pixel). For example, onsemi's NCV78702 and NCV78723 (dual-channel buck), combined with the pixel light control chip, form a complete solution that can drive multiple LED light strings up to 60V.
Among them, NCV78702 is a single-chip high-efficiency boost converter for LED driving, specially designed for automotive headlight applications, such as high beam, low beam, DRL (daytime running lights), turn indicators, fog lights, static turns, etc. It includes a current mode voltage boost controller with minimal external components and customizable output voltage. Two NCV78702 can be combined together to form a multi-phase boost circuit to further optimize the filtering effect of the booster and reduce BOM cost.
NCV78723 can drive 2 LED strings 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 sense resistors to regulate the buck current and the output current can be customized. When more than 2 LED channels are required on one module, 2, 3 or more NCV78723s can be combined together.
The rear lights are used to remind surrounding vehicles and pedestrians of the vehicle's upcoming driving intentions, including turning, braking, parking, etc. At the same time, the various shapes on the body can also be used as a sign of the car's identity. The operating current is generally less than 100mA. The rear combination lights have these high-end functions: enhanced parking lights, tail lights, and turn lights are dynamic segmented light signals. They can also use beams to create branding, welcome, animation and other effects, and can drive single or multiple strings. LED lamp beads have higher energy efficiency, less loss, and include safety diagnostic functions.
The NCV7683 consists of eight 100mA linear programmable constant current sources and is suitable for LED-based rear combination light adjustment and control and flashing functions in automotive applications. System designs with the NCV7683 enable two programmable levels of cutoff (100% duty cycle) and tail lighting (programmable duty cycle), and can also implement optional external PWM control. LED brightness is easily programmable with two external resistors (cutoff programmed as absolute current value, tail programmed as duty cycle). The use of optional external ballast FETs enables power distribution on designs requiring high current. Backoff power limiting reduces drive current during overvoltage conditions. This is most useful for low power applications where external FETs are not used.
Flexible and brilliant interior lighting
Since LED has great advantages in color temperature, color rendering index, brightness, etc., it is very suitable for short-term use in the car. Common ones include instrument lighting, step lights, door lights, trunk lights, reading lights, ceiling lights, etc. . In addition, LEDs can also be used to represent vehicle status. For example, whether the door is closed or not 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 interference to the driver's line of sight, thereby effectively reducing driver dazzling.
ON Semiconductor can provide various discrete and integrated solutions to fully meet the needs of various lighting applications. These range from simple solutions such as the double-terminal constant current regulator (CCR), an economical yet robust device that provides an efficient current regulation solution for cost-sensitive automotive LED lighting; to some more complex solutions The solution includes a LIN RGB LED driver, which combines 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 regulator (CCR) is a simple, economical and rugged device suitable for providing a cost-effective solution for regulating current in LEDs (similar to a constant current diode CCD). This CCR is based on self-biased transistor (SBT) technology and regulates current over a wide voltage range. It uses a negative temperature coefficient to protect the LED from thermal collapse under extreme voltages and currents.
RGB and white LEDs complement each other, and their development is driven by the drive to further personalize vehicles. They are used as programmable interior light sources, including special effects applications such as area lighting and ambient lighting on the dashboard, center console, navigation/audio, etc. The NCV7430 is a single-chip RGB driver for specialized multi-color LED applications. This RGB LED driver contains a LIN interface (slave interface) for parameterized programming of LED color and chromaticity. The device receives commands via the LIN bus and drives the LEDs individually. The 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 NCV7430's LIN address is programmable in the device's internal memory. A feature of the device is 24-bit true color, which allows the module to output 16 million different colors through LIN commands, which can be used to create a personalized interior atmosphere in the car.
Summarize
For application fields such as headlights, matrix/pixel lights, and rear combination lights, ON Semiconductor provides comprehensive semiconductor solutions. These solutions not only have high energy efficiency, high integration and excellent reliability, but also benefit from the platform design concept to achieve excellent scalability and flexibility. This undoubtedly brings great convenience to designers, helping them to move smoothly on the road to innovation, while simplifying and accelerating the product development process. In addition, ON Semiconductor's smart power supply combined with advanced intelligent sensing technology has laid a solid foundation for improving road traffic safety.