In today’s mid-to-high-end cars, the modern lighting concept is more and more vividly interpreted. Both exterior and interior lighting are stylish and personal, with mood settings used in different parts of the car to control the color and brightness of light in “personal spaces”, such as the driver’s footwell or the backlighting of the console. This type of automotive lighting uses a new type of light source, which not only enriches the consumer experience, but also meets the requirements of environmental protection and energy saving.
To achieve advanced automotive lighting applications, there must be the support of corresponding semiconductor technologies. As a leading automotive lighting solution supplier, ON Semiconductor has been providing various general and dedicated high-efficiency device solutions for automotive lighting applications, in line with automotive applications. strict requirements to meet the rapidly developing market demand.
modern car lighting system
In recent years, light emitting diodes (LEDs) have been widely adopted in automotive lighting applications. Compared to incandescent lamps, LED-based lighting systems have a longer lifespan, lower power consumption, and greater design flexibility. These properties make it ideal for automotive interior lighting applications. In addition, as technology continues to advance, lower cost white LEDs with higher light output per watt are emerging, making LEDs more suitable for various lighting applications in the interior of the car.
LEDs are used in a wide variety of applications, such as in the headliner or in the lower trim of the doors, focusing light on specific areas inside and outside the car. LEDs can also be integrated near door handles, key holes, pedals, cup holders, or as turn signals on mirrors. The shape of the luminous indication can be very simple, or it can be very delicate to meet the precise lighting, provide convenience and beauty for people, as shown in Figure 1.
Figure 1: Various automotive lighting applications
Advanced Automotive Lighting Solutions from ON Semiconductor
ON Semiconductor has been providing standard products and custom devices for automotive lighting applications, including common light bulb driver solutions, as well as stepper drivers, LED drivers and high-intensity discharge lamp (HID, such as xenon) drivers. In the HID drive application-specific integrated circuit (ASIC) market, headlamp leveling and rotary stepper drivers developed by ON Semiconductor have been widely adopted in the industry. In the automotive LED lighting market, ON Semiconductor provides a rich product portfolio for both interior and exterior applications. In the block diagram of the automotive lighting system shown in Figure 2, ON Semiconductor has various corresponding products. Several main solutions are described below.
Figure 2: Block Diagram of Automotive Lighting System
1. Headlamp stepper motor driver
Most of today’s cars are equipped with halogen lamps with high beam (HB) and low beam (LB) functions, which are the main function of headlamps. High beam halogen lamps have a typical power consumption of 55 W and a light output of about 1,000 lumens. HID technology has been around for more than ten years, with a power consumption of about 35 W and a light output of about 3,500 lumens, which has certain application advantages. Over time, HID lamps have incorporated high beam functionality into bi-xenon solutions. However, because the high brightness and glare of HID can affect the line of sight of approaching vehicles, some countries require automatic adjustment of the height of the low beam.
Another important aspect of automotive headlights is the Advanced Front Lighting System (AFS) beam rotation to optimize the visibility curve, while the Adaptive Driving Beam (ADB) function adjusts the beam according to real-time conditions. Stepper motors are the controller of choice for AFS and ADB.
ON Semiconductor’s AMIS-30623 single-chip bipolar stepper motor driver is suitable for headlamp leveling and rotation control. With an integrated position controller and local interconnect network (LIN) interface, the device enables the design of a dedicated mechatronic solution for remote connection to a LIN host, see Figure 3. It uses configurable parameters such as current, velocity, acceleration and deceleration to receive position commands over the bus and drive the motor coils to the desired position. The AMIS-30623 can also detect motor stalls.
The device embeds a dedicated finite state machine and a LIN instruction set tailored to the requirements of advanced headlamp systems. It also integrates sensorless step loss detection to improve reliability while reducing component count and board space. Product Cost.
Figure 3: Headlamp Leveling and Rotation Circuit Using AMIS-0623
2. LED headlamp system power ballast and dual LED driver
At present, most cars still use halogen headlamp solutions to provide high beam and low beam functions, but the future trend is to use xenon lamps and LED lamps. In particular, the application of LED lights, which can greatly reduce the power consumption of headlights, will increase rapidly, and 30% of cars will be equipped with multiple LED headlight functions within five years. LED lighting offers a sleeker option for “instant” lighting and allows brightness control from 0% to 100% power.
ON Semiconductor’s NCV78663 single-chip smart headlamp LED driver is a new device to be launched in 2011 that supports single-module control of high beam, low beam, daytime running lights, position lights, turn signals and fog lights . With integrated digital dimming, programmable serial peripheral interface (SPI) settings, and built-in diagnostics, the NCV78663 provides an integrated and comprehensive energy-efficient solution for headlamp control.
Figure 4: NCV78663 Single-Chip Smart Headlamp LED Driver
The NCV78663 uses a buck/boost topology to achieve LED current regulation, constant current sharing, high-efficiency integrated buck switching (high-side), and current up to 2 A using only a few external components; its extended diagnostic capabilities include: Open circuit or failing driver, short circuit, over current protection and single LED failure, etc. In addition, the device features thermal protection, system customization via SPI interface and/or OTP settings, multiple system configurations with one device, better EMC performance without additional filtering, low battery EMC, low LED string EMC, and more . Using the NCV78663 reduces the number of external components, and the total energy efficiency is better than 90%. An evaluation board for this device is available, see Figure 5.
Figure 5: NCV78663 Evaluation Board
3. HID headlamp full-function ASIC
The advent of HID lamps improved the performance of headlamp systems. Compared to traditional halogen lamps, HIDs have improved color rendering, low power consumption, longer life and higher light output. To support advanced functions, HID headlamps require high-efficiency ballasts and complex control circuits.
The ON Semiconductor HID lamp control system is a hybrid analog/digital solution using an 8-bit microcontroller or dedicated state machine, see Figure 6. The device integrates a DC/DC controller, as well as rich diagnostic functions (overvoltage, undervoltage, temperature sensor, life counter), various communication interfaces (LIN, SPI), and supports 35 W (D1/D2/D3/D4 ) and 25 W (D5) lamps.
Figure 6: HID headlamp full-featured ASIC
4. Linear current stabilization and controller for automotive LED combined taillights
At present, automotive combination taillights (RCL) are increasingly using LED light body groups, which not only have beautiful appearance and high light efficiency, but also help the rear car to clearly see the driving state of the preceding car.
ON Semiconductor’s NCV7680 is a linear current regulator and controller that can power combination taillights from a single chip, providing better performance and higher energy efficiency in a smaller footprint than solutions on the market. The device includes 8 linear programmable constant current sources suitable for current regulation and control of automotive solid-state combination tail lamps (RCLs), supporting light-emitting diode (LED) drive currents up to 75 mA per channel.
The NCV7680 integrates numerous functions and supports two brightness levels, one for parking and the other for tail lighting. Optional pulse width modulation (PWM) control is also available if desired. The system designer only needs to use an external resistor to set the output current (overall set point). In addition, for designs requiring high currents, optional external ballast field effect transistors (FETs) can be used for power distribution according to the high currents required by the design. The delayed power limit reduces the drive current in overvoltage conditions. This is important for low current applications without external FETs.
Typical applications for this device include combination tail lights, daytime running lights (DRL), fog lights, center high mounted brake light (CHMSL) arrays, turn signals and other external modulation applications, liquid crystal Display (LCD) backlighting, lighting modules, and more. Compared with discrete solutions, the device can better match the LED output, open-drain output function of open LED string diagnosis, easy to find faults.
Figure 7: Application circuit with external FET transistor ballast
ON Semiconductor has been leveraging its advanced automotive process technology to provide a variety of standard products and custom devices for automotive lighting applications. In addition to some of the solutions introduced above, there are also industry-leading products and solutions such as LED drivers using linear and switching power supplies (SMPS), LED current regulators, and central high-position brake light constant current regulators.
Like various automotive application products using advanced automotive process technology, all these integrated circuits meet the specifications and environmental protection requirements of automotive reliability and temperature, Lights, position lights, and especially new light sources are increasingly demanding, allowing drivers to fully experience the comfort and fun brought by lighting.