Top 10 automotive LEDs and drivers

Demand continues to grow for automotive LEDs, particularly in high-end vehicles to enhance aesthetics, while enabling automakers to customize and differentiate their lighting designs. In addition, LEDs consume less power, offer a longer life and provide better illumination over traditional lighting technologies. Many of the latest developments, including for LED drivers, focus on miniaturization and higher integration to save space and deliver sleeker designs, greater power savings and improvements in brightness and color control.

A big driver for LED lighting is greater differentiation in the car’s exterior and interior, which also requires increasingly smaller lighting and power components. Over the past year, LED manufacturers have developed new devices in smaller packaging and simpler designs and implemented new technologies and processes to reduce color variations. LED driver manufacturers continue to enable easier integration and improve performance in areas such as heat dissipation and flexible color control.

While exterior lighting—front and rear lighting, brake lights and turn signals—plays a big role in vehicle safety and there continues to be increased adoption of LEDs for improved visibility, including for adaptive lighting, ambient and accent lighting applications have been a big focus area for LED manufacturers over the past year.

Here are a few examples of LEDs and LED drivers introduced over the past year that deliver on these benefits.

Automotive LEDs

LED manufacturers continue to improve RGB LEDs for automotive interior applications, including ambient and accent lighting. Offering greater illumination choices for applications such as instrument clusters and infotainment and information displays, these new devices also simplify design and lower cost.

One of the latest innovations is ams Osram’s intelligent RGB LED, the OSIRE E3731i LED. This LED enables automotive manufacturers to implement novel dynamic lighting effects in vehicle interiors. This dynamic lighting combines changes in color and brightness with pulsing, breathing or moving light effects.

Used for both decorative and functional purposes, the OSIRE E3731i LED allows up to 1,000 LEDs to be connected in a daisychain, controlled via one microcontroller (MCU). The interior lighting is achieved using simpler architecture, fewer components, less wiring and a lower system cost, the company said.

The OSIRE E3731i LED is designed for interior applications that need high dynamic RGB lighting. The RGB LED is co-packaged with an IC that integrates three LED drivers. It also includes optical measurement data of the three RGB LEDs. The external MCU addresses and controls each device via an Open System Protocol (OSP), allowing the MCU to run any color algorithm and optimize the color algorithm.

Other features include a serial bus interface supporting the OSP, a temperature sensor and on-chip memory. The OSIRE E3731i is qualified to the latest AEC-Q102 Annex 3 standard.

Each RGB LED is factory-characterized and optical performance data is stored in the LED’s on-chip memory. The on-chip memory facilitates end-of-line calibration of interior lighting systems, very high optical uniformity and consistency when using arrays of hundreds of OSIRE E3731i LEDs, ams Osram said.

Rohm Semiconductor also introduced a new RGB LED (SMLVN6RGBFU) for automotive interiors. Applications include function and status indicators in instrument clusters, center information displays, and accent lighting for footwells and door handles. This RGB chip LED minimizes color variations due to color mixing, delivering accurate color representation.

Rohm said there is increasing demand for RGB chip LEDs capable of providing a range of colors to indicate operational status in instrument panels and meter clusters, as well as a need to create a comfortable and luxurious cabin space with decorative lighting using RGB LEDs. It is housed in a small, 3.5 × 2.8-mm package size with a low height.

The SMLVN6RGBFU LED chip minimizes color variation by precisely controlling the luminous characteristics of the RGB elements and improving color mixing through in-house device technology. This includes original element color mixing control technology in combination with Rohm’s vertically integrated production system from the element fabrication stage.

Rohm also supports detailed color matching tailored to user specifications with the chromaticity simulation system, which enables precise color matching. The SMLVN6RGBFU sets adjustment coefficients for each chromaticity rank while providing calibration to bring the color closer to the desired target.

Also extending its RGB LED family for automotive interiors, Dominant Opto Technologies has added a 0.5-W RGB LED (S6RTB-EHG) to its SpicePlus 3030 multi-color family, providing more power and brightness selections for electric-vehicle and dynamic ambient lighting requirements. Applications include door panels, cup holders, footwells and EV charging port indicators.

The new S6RTB-EHG RGB LED joins the 0.7-W S6RTB-THG device. Housed in a small package, the S6RTB-EHG features high-brightness red (typically 24 lumens [lm]), true green (typically 40 lm) and blue (typically 8 lm), with a drive current of 150 mA for each chip, which is suitable for high-luminance automotive functions. The maximum current is 200 mA.

The SpicePlus 3030 multi-color S6RTB-EHG has a high operating temperature of 125^°C and an LED junction temperature of 150^°C. The RGB LED offers low thermal resistance and excellent thermal performance, according to the company. It is housed in a 3 × 3 × 0.7-mm package with a small, light-emitting surface of 2.6 × 2.4 mm, enabling it to be used with modern narrow light guides with diameters as small as 3 mm.

In addition, the S6RTB-EHG is built with a gold-plated lead frame for higher corrosion robustness and is qualified to AEC-Q102 H2S Test Class A.

Earlier this year, ams Osram also launched a series of LEDs for automotive exterior lighting. The new SYNIOS P1515 family of sidelooker, low-power LEDs simplifies design. They enable the creation of a homogeneous appearance in extended light bars and other automotive rear lighting applications.

Typically, an automobile rear combination lamp (RCL) requires a complex and deep optical assembly consisting of diffusers and light guides to spread the bright points of light from conventional toplooker LEDs without producing visible dark and bright spots, ams Osram said, and by replacing toplooker LEDs with the SYNIOS P1515 sidelookers, automotive manufacturers can achieve a smooth, homogeneous appearance across the width of the vehicle.

An RCL or turn indicator can be much thinner with a simpler optical assembly, thanks to the sidelooker LEDs, with the same number of LEDs in the toplooker-based application. This opens up the possibility for distinctive shapes in the RCL.

Alternatively, a homogeneous appearance can be achieved with the same depth of optical stack as for toplooker LEDs, with “substantially” fewer LEDs and LED drivers, reducing cost and simplifying the circuit configuration, the company said. It can reduce the number of LEDs and drivers by as much as 66%.

The SYNIOS P1515 LEDs are AEC-Q102-qualified. They produce a side-emission output with uniform 360° light intensity all around the device. Light is also emitted from the top of the LED, but at a lower intensity than from the sides, to ensure no bright or dark spots. The SYNIOS P1515 family is available in red (621 nm), super-red (633 nm) and yellow (587 nm) in a 1.5 × 1.5-mm footprint.

Earlier this year, Himax Technologies Inc. and its subsidiary, CM Visual Technology Corp. (CMVT), announced their collaboration with Ta Yih Industrial Co. Ltd. to jointly develop an LED edge-lit-type automotive lighting application featuring CMVT’s nano-optical film technology. It uses an innovative design that shifts the light source from the conventional downward direct-lit type to a side-emitting one.

The side-emitting LED light is reflected or refracted by leveraging an optical film toward the illumination direction of the automotive lamps, achieving a more uniform distribution of light compared with traditional direct-lit-type designs while reducing the size of automotive lighting fixtures, according to the companies.

CMVT’s nano-optical film allows for precise control of light direction for higher light-guiding performance compared with conventional optical films, which further enhances light uniformity and improves light efficiency while also reducing the number of side-emitting LEDs required.

The nano-optical film also supports flexible pattern design along with dynamic and multi-gray scale displays. This introduces a new level of customization and diversification to automotive lighting designs and provides visually attractive lighting solutions, Himax said.

Automotive LED drivers

For automotive ambient lighting, Melexis recently extended its LIN RGB LED driver family with the introduction of the miniaturized MLX81123. This third-generation LIN RGB LED is housed in a SOIC-8 and a small DFN-8 3 × 3-mm packaging, enabling the use of light in any location where there were previously limitations due to space constraints.

The MLX81123 is manufactured using silicon-on-insulator technology, and the RGB driver’s miniaturization allows for an increased number of ICs per wafer, providing a significant increase in production volume output. The RGB driver offers pin-to-pin compatibility (SOIC-8) with its predecessor and uses common software design, making it easier to integrate into existing designs, often without a full development cycle, the company said.

The advanced 16-bit MCU is equipped with 2-kB RAM, 32 kB of application-usable flash and a system ROM with a bootloader and LIN driver. A built-in E²PROM allows for configuration, such as LED calibration coefficients, which are needed to ensure uniform cabin brightness and color representation.

The MLX81123’s LIN system includes a transceiver and protocol handler, which enables the seamless connection between RGB ambient modules and the pre-existing LIN network of the vehicle. Featuring four high-voltage I/Os with free configurable current sources (up to 60 mA), the MLX81123 can support RGB and white LEDs from a wide range of suppliers. The IC’s independent 16-bit pulse-width modulation (PWM) output provides precise color and brightness control of any connected LEDs, making it suited for a variety of vehicle ambient applications, such as door trim, accent and interior cabin lights.

In sleep mode, the MLX81123 offers a typical standby current consumption of 25 µA. Other features include a 28-V jump-start and battery monitoring with over- and undervoltage detection. The operating temperature is –40°C to 125°C, with a built-in temperature sensor for thermal monitoring, making it suited for demanding automotive environments.

The MLX81123 supports system integration up to ASIL B under ISO 26262 and is suitable for bus systems according to LIN 2.x and SAE J2602.

Lumissil Microsystems Inc. claims a new standard for dynamic interior automotive lighting with the introduction of the IS32FL3202 RGB LED driver with CAN bus that enables a quick response for LED strings with up to 256 RGB LEDs.

This smart LED driver is reported to significantly increase the number of addressable RGB LEDs within a single communication channel, delivering dynamic color and intensity changes across hundreds of RGB LEDs. Automotive cabin lighting applications include decorative trim, roof starlight, and integrated seat and door RGB lighting.

Lumissil said up to 256 RGB LEDs connected in a single daisychain string and multiple other LED strings can be controlled by a single industry-standard MCU, and the die can be co-packaged with LEDs to offer integrated SMART LEDs.

In addition to the WFDFN-10 (3 × 3 mm) package, the IS32FL3202 is offered in die form, with a layout optimized for LED integration. The co-packaged SMART LEDs are factory-calibrated, digitally addressable RGB LEDs with an integrated IS32FL3202 smart LED driver. This design eliminates the need for LED binning and manufacturing line calibration, the company said.

The IS32FL3202 is a three-channel smart LED controller, with each channel supporting 6-bit current adjustment for color setting and 12-bit PWM for smooth LED dimming control. It operates within a voltage range of 3.5 V to 6.5 V over the temperature range of –40°C to 125°C.

The new smart RGB LED driver technology simplifies the implementation of dynamic color and intensity-changing arrays of hundreds of RGB LEDs in car interior lighting, Lumissil said.

The IS32FL3202 incorporates a state machine core that enables low-latency communication with any MCU over a CAN bus interface, speeding up the transmission of instructions for individual LED brightness and color control. The integrated state machine also measures the RGB LED temperature and uses a built-in temperature compensation algorithm to ensure consistent luminance over a wide temperature range. The temperature-compensated PWM data is stored in 16-bit registers. All of the IS32FL3202 registers can be accessed and updated via the fast CAN bus.

To minimize EMI, the IS32FL3202 supports spread spectrum on the PWM clock generator. It supports location address assignment for addressing hundreds of RGB LEDs without the need for address pins. The maximum output current of each LED channel is 63 mA.

Targeting both interior and exterior automotive applications, Novosense Microelectronics recently introduced a 16-/24-channel LED driver for automotive LED applications, including rear lights, exterior lights and general automotive interior and body lighting. It features flexible dimming and control features for dynamic vehicle lighting and offers a variety of driving options for up to 16/24 channels.

The automotive-qualified NSL21916/24 meets the requirements for high-channel-count linear LED drivers in new and emerging automotive lighting systems being developed to meet functional, safety and aesthetic design requirements, Novosense said.

The NSL21916/24, supplied in an HTSSOP38 package, offers a low dropout voltage of 600 mV maximum (at 50 mA) and provides multiple regulations with LED open-circuit, LED short-to-ground and single-LED short-circuit diagnostics. The series also includes a configurable watchdog timer that can be used to automatically configure failsafe states when connection to the host MCU is lost, and a thermal sharing mechanism that dissipates heat via a shunt resistor protects against excessive temperature rises, Novosense said.

The NSL21916/24 LED driver is qualified to AEC-Q100 Grade 1 (junction temperature from –40°C to 150°C). These multi-channel LED drivers support individual control and high-side currents of up to 100 mA for each channel. They also feature a 2-bit global and 6-bit individual current setting combined with 12-bit independent PWM dimming and phase-shift PWM dimming capabilities for precise and flexible LED brightness control.

Other features include an on-chip programmable E²PROM that allows the same device to be configured for different applications, as well as a built-in UART/digital interface that supports a variety of control and diagnostic functions. A standard CAN physical layer allows this interface to be used for long-distance, off-board communications without any impact on EMC, the company said.

Also targeting interior and exterior automotive applications is Diodes Inc.’s AL1783Q automotive-compliant, three-channel linear LED driver that enables users to independently control the brightness and color of its three channels. Qualified to AEC-Q100, these devices target multiple interior and exterior lighting applications in EVs and internal-combustion-engine vehicles.

The demand for multi-channel LED drivers is driven by human-centric automotive design, which allows users to easily change the interior lighting colors, Diodes said. In addition, these drivers help increase safety levels by simultaneously enabling animated turning-indicator signals and exterior grill lighting for different road conditions, the company added.

Key features include LED current settings by an external REF pin, independent dimming controls for each channel and PWM for LED dimming. It also provides multiple fault-detection features, including undervoltage lockout and overvoltage protection, as well as the ability to detect LED open- and short-circuit conditions.

As the automotive industry moves toward higher-voltage rails to power vehicle subsystems with battery voltages increasing up to 48 V, the AL1783Q has been designed to operate from a 55-V rail. This provides an advantage over other LED drivers, which typically operate only up to 40 V, and enables the AL1783Q to support increasing LED chain voltages, Diodes said.

The LED driver also delivers up to 66% more current per channel (250 mA, compared with a standard 150 mA), which provides greater flexibility to support higher LED current ranges in a wider range of lighting applications. The current in each of the three channels can be set using individual resistors.

The AL1783Q is housed in a thermally efficient TSSOP-16EP (5.1 × 6.6 mm) package with an exposed cooling pad for higher heat dissipation.

Rohm Semiconductor has launched a new BD94130xxx-M series (BD94130MUF-ME2 and BD94130EFV-ME2) of LED driver ICs for automotive LCD backlights. These LED drivers provide local dimming capabilities to improve visibility and reduce power consumption in automotive display and control up to 192 zones. They can be used in large and higher-resolution displays that are increasingly used in car infotainment and instrument clusters for improved visibility. Applications include electronic mirrors, instrument clusters, car infotainment and head-up displays.

A single conventional direct-type LED driver IC controls less than 100 zones; however, this is a challenge, as the number of components increases with larger displays with more zones, Rohm said.

The BD94130xxx-M series can control more zones than conventional ICs, reducing the number of LED drivers required. These matrix LED drivers feature an eight-line switch controller with a 24-channel current driver that can be divided into eight lines, enabling dimming of up to 192 zones of mini-LEDs for backlighting with one IC. The mini-LEDs in each zone can be independently adjusted by using a local dimming function, which contributes to a larger contrast ratio and lower-power-consumption displays, Rohm said.

The number of switch controller lines can be selected from three patterns (four, six or eight) using register settings to address a variety of zones and LED current-consumption specs. Built-in feedback control provides a constant feedback voltage independent of LED temperature characteristics, reducing thermal design time as well as loss ratio.

For example, in mainstream 10-inch-class infotainment displays that consist of approximately 600 zones, the new LED drivers enable operation with just one-fourth of the number of LED drivers compared with existing (48-zone) products. This decreases the LED driver mounting area by approximately 84%, according to Rohm, and will deliver an increased advantage as screens become larger and the number of zones increases in next-generation cockpits.

The AEC-Q100-qualified BD94130xxx-M devices are embedded 24-channel constant-current drivers with 12-bit PWM dimming. Features include phase-shift function, 6-bit dot correct (50% to 100%), LED open and short detection, PGATE short protection, VINSW overvoltage protection and adjacent LEDCH short detection.