Intelligent automotive lighting is evolving, shifting to LED-based solutions to improve road safety, achieve energy savings of 3 to 5 times, enhance user experience, and innovative lamp styling design and reliability improvements, but also continue to broaden the new horizon of automotive lighting. ON Semiconductor (onsemi) focuses on the development of trends in the automotive field and continues to introduce innovative smart power and smart sensing technologies to ensure road safety, and is also a pioneer and leader in the field of automotive lighting. This article focuses on system-level applications for automotive exterior lighting and ON Semiconductor's semiconductor solutions for related designs, including matrix/pixel lights, styling customization and Vehicle-to-Everything (V2X). 

Headlight and SPI Interface LED Driver Modules 

ON Semiconductor's LED driver modules offer higher integration and reliability, platform design provides scalability and flexibility for a variety of headlight designs, intelligent function partitioning helps reduce costs, and achieves unique forward lighting effects that reduce carbon emissions and help increase the range of electric vehicles. It contains LED driver chips, stepper motor driver chips, various sensor interfaces, power supply and power management chips, interface protection chips, Telematics chip SBC and microcontroller, etc. It is a small system that can work independently. 

ON Semiconductor has developed 4 generations of SPI-LED driver products. The 2nd generation is Boost-Buck chip NCV78763, the 3rd generation has multi-channel Buck chip NCV78723 and multi-phase Boost chips NCV78702 and NCV78703, with a maximum output voltage of 60 V, which is the highest voltage output capability of the same type of products on the market, and the 3rd.5 generation is multi-channel synchronous rectifier Buck chip NCV78825, drive current capacity up to 3 A, is also the largest current drive capacity in the same type of products on the market. The products after the 3rd generation are suitable for more than 3 groups of LED strings. 

If two NCV78763 are used, four different LED strings can be driven, and two Boosts can be connected in parallel to output more power, but this is only a simple power addition, for driving higher power LED light sets, it is recommended to use multi-phase alternating working Boost chips. In practical applications, one NCV78702/NCV78703 can be combined with multiple NCV78723 to drive 4 to 12 LED strings of different power, fully covering far light, near light, column, turn, corner light, fog light and other functions. 

Advantages of Boost-Buck power supply structure 

Boost acts as a stable voltage source to safeguard the voltage drop requirement accumulated by multiple LED strings.

Pixel controller for matrix/pixel headlights 

Advanced matrix/pixel light sets optimize headlight function in a variety of driving scenarios, including illuminating longer distances, switchable beams when turning, while illuminating pedestrians and obstacles in the road more clearly, minimizing glare from oncoming traffic, controlling individual LED pixels on and off as needed, and including features such as safety diagnostics and Telematics.

LED Light Packages - Series vs. Parallel Drivers 

In a wide range of vehicle lights, there are two types of LED light clusters to drive: series and parallel. The matrix/pixel LED cluster described above is a series-connected structure. When the rated operating current of the LED beads is greater than 300 mA, the series type structure is generally chosen, and the disadvantage of this structure is the large voltage drop. ON Semiconductor's LED driver chips have a Boost controller that can boost up to 60 V, and the Buck chip is responsible for controlling the stable current output of the entire string. The NCV78247 integrates 12 matrix switches with an overcurrent capability of 1 A each, including an SPI interface. It can be used not only for matrix light sets consisting of high and low beam, but also for turn signals, daytime running lights, grille lights and modeling lights with animation effect. 

LED linear driver for rear combination lights (parking lights, tail lights, turn signals, modeling lights) 

These lights are signals used to alert surrounding vehicles and pedestrians of the car's impending driving intentions, including turning, braking, parking, etc., while the various shapes on the body of the car can also serve as a form of identification for the car's identity, and the operating current is generally less than 100 mA. rear combination lights have these higher-order functions: enhanced parking lights, taillights, turn signals are dynamic segmented light signals, and innovative light shapes can achieve to create branding, welcome, animation and other effects with light beams, can drive single-string and multi-string LED beads, higher energy efficiency, less loss, and include safety diagnostic features. ON Semiconductor provides single-channel and multi-channel LED linear drivers, as shown in Figure 6. The single-channel pre-driver chips are NCV7691/92, the multi-channel pre-driver chips are NCV7693, and the multi-channel direct driver chips are NCV7683 dedicated for braking and parking, and NCV7685 with I2C interface. 

LED Constant Current Regulator 

This is a cost-effective solution for simple headlight applications. Designers can match the most suitable device for the application based on the key parameters in the table below. These LED constant current regulators provide constant current over a wide voltage range, resulting in constant brightness. The negative temperature coefficient protects the LEDs under high temperature conditions. 

Summary 

Automotive exterior lighting is opening the way for further improvements in user experience and safety, with increasingly diverse options for brand equivalence and styling, and increased reliability, all of which continue to broaden the new frontier of automotive exterior lighting. ON Semiconductor offers semiconductor solutions for headlights, matrix/pixel lights, and rear combination lights with high efficiency, integration, reliability, and platform design for scalability and flexibility, helping designers innovate and simplify and accelerate development. ON Semiconductor's smart power supplies with intelligent sensing technology pave the way for improved road safety.