New Allegro LED Drivers Bring High-End Lighting Technology to Mainstream Vehicles, Enhancing Automotive Safety

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Allegro MicroSystems, Inc. (“Allegro”), has expanded its automotive lighting portfolio to include two new offerings for advanced driver assistance system (ADAS) applications. A unique solution in the market, the A80803 leverages multi-topology conversion and patented IP to enable smooth high/low/high beam transitions in a single integrated circuit (IC). The A80804 linear LED driver provides high power for automotive lighting applications through multiple, independently-configurable channels. Both products help designers reduce the number of ICs required to create safety-enhanced automotive lighting systems, enabling higher performance and more compact designs at lower system cost.

Vehicle lighting plays a key role when it comes to driver and passenger safety. According to a recent study by the Insurance Institute for Highway Safety (IIHS), driving at night is three times riskier than driving during the day, and crash rates for vehicles that have headlights with an IIHS “good” rating are nearly 20 percent lower than ones with a “poor” rating. ADAS applications and lighting enhancements that improve night-time road and vehicle visibility can significantly improve driver response times, helping prevent crashes and saving lives.

The A80803 is a switch-mode, constant-current controller for high-power LED automotive lighting applications that addresses many common pain points for headlight designers, with innovative features that make it easier for headlight designers to bring advanced functionality to mainstream vehicles. The multi-topology single-ended controller design, combined with wide input/output voltage capability, provides a universal solution for a wide variety of use cases and/or number of LEDs. Options for SPI-based control or EEPROM-based end-of-line programming for standalone operation further extend the range of possibilities.

The A80804 is Allegro’s first four-channel linear driver for high-power LEDs. In addition to targeted applications such as DRL/position and stop/tail lights, it gives lighting designers increased design flexibility for popular features such as sequential turn signals, animation effects, and theater-style transitions. No switching elements or inductors are required, and the A80804’s low EMI output helps it achieve CISPR25 Class 5 compliance. It also offers multiple analogue and PWM dimming methods, dual brightness mode operation, and is configurable without the need for a micro controller.

“Today’s high-end and luxury cars have comfort and safety features that take years to make their way into less-expensive mainstream vehicles, mostly due to solution costs” said Mark Gaboriault, Product Line Director for Regulators and Lighting at Allegro. “The A80803 gives headlight designers a compact, cost-effective solution that automatically manages the electrical transition from low to high beam, without the need for multiple LED drivers and local micro controllers. It’s a unique offering that will help democratise headlight design and help increase driver safety. Today’s consumer also expects an engaging, personalised driving experience. With the A80804, lighting designers now have a cost-effective way to enable animations and other lighting effects in a way that simplifies the design process while enhancing visibility and driver safety, as well as minimising bills of materials.”

Features and Benefits

The A80803 includes first-to-market features that help simplify headlight design and increase driver safety:

  • Multi-topology high/low beam switchover, removing the need for a second LED driver IC
  • A unique slew-control feature that minimises LED current overshoot and under­shoot while transitioning between high and low beams
  • Two configuration options including factory-programmed EEPROM to remove the need for a local micro controller, and an SPI interface for control and status registers to enable software control
  • Extensive diagnostics for ASIL capability, with two programmable fault pins and reporting via SPI
  • Multiple methods for analog LED setting/control for base intensity, foldback for thermal conditions via NTC, or using a single design with different LED “bins”
  • Multiple methods for PWM LED control via an internal PWM signal (standalone mode) or an external PWM signal for direct PWM control on the EN/PWM pin (MCU mode)

Innovative features in the A80804 help lighting designers simplify system design while increasing safety:

  • Linear control over four channels, each with an independent enable/PWM input
  • Multiple methods for PWM LED control via an internal PWM signal (standalone mode) including automatic phase shifting, or an external PWM signal for direct control on the EN/PWM pin (MCU mode)
  • Ability to switch between low and full intensity for applications including stop/tail or DRL/position lighting, without the need of a local microcontroller
  • Selectable LED current slew-rate control for tuning PWM edge times, improving EMI performance
  • Multiple methods for analog LED setting/control, LED binning, NTC foldback, or hybrid dimming
  • Integrated/optional derating for high Vin and/or temperature
  • Unique “MINOUT” function that can significantly reduce power losses by dynamically adjusting for the inherent changes in LED Vf versus temperature
  • Extensive protections to protect the device and the LEDs, reported via fault pin
  • Ability to parallel multiple devices together in order to extend the number of strings

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