Integrated automotive IC from STMicroelectronics consolidates door-mounted drivers for cost, assembly, and reliability advantages

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STMicroelectronics is the first to introduce a single chip that produces the major signals required to drive vehicle door-mounted systems as well as an improved method for controlling electrochrome (EC) rear-view mirrors.

The L99DZ70XP combined driver IC eliminates discrete drivers normally mounted in multiple locations inside the door, allowing compact, integrated door-zone controllers that are easier to fit and deliver greater long-term reliability.

The expected ‘creature comforts’ inside modern cars include numerous powered systems that are mounted inside driver and passenger doors. In addition to motor-driven door-mirror adjustment, other mirror functions can include powered folding when the vehicle is parked, a heater for automatic defrosting, and electrochrome dimming to enhance night-time driving comfort. Motor-driven locks and deadlocks also enhance convenience as well as security in many types of vehicles. In addition, lighting features including interior orientation lighting, such as footwell lights, as well as functional lighting, such as safety lights or turn indicators, are also expected. In these lighting circuits, different lamp-driving characteristics are required depending on whether LEDs or conventional bulbs are used. By consolidating all the driver circuits for these high-end features on a single chip, the L99DZ70XP saves design and mounting of multiple individual assemblies, thereby reducing cost and time to market as well as saving space. By eliminating many connections and potential failure points, this single-chip solution also increases field reliability.

The L99DZ70XP’s integrated EC-mirror controller is a first for automotive driver ICs. Conventional EC controllers typically use a regulator that requires a high-power external resistor, but the L99DZ70XP generates control signals for a small external MOSFET driving the EC element. This saves space and cost, and also allows closed-loop current control for enhanced reliability.

Six of the L99DZ70XP outputs are optimized for motor-drive applications such as mirror positioning and folding, and door-lock actuation. Up to four drivers are available for lighting applications, and two of these can be programmed to drive either LEDs or conventional bulbs. Another output is optimized to drive the mirror defroster. Each of the drivers uses pulse-width modulation for accurate current control. Other capabilities include soft starting for loads such as motors or bulbs, to prevent high initial currents causing potentially damaging surges within the vehicle wiring. Preventing such surges is extremely important as cars evolve to include increasingly sensitive electronic systems. The L99DZ70XP uses serial communications over an industry-standard SPI link to exchange information with the host controller, including diagnostic information for each output to aid fault-finding and repair.

The L99DZ70XP adds to ST’s Door Zone family of integrated drivers, which already features seven devices offering a range of functions for driver-side, front-passenger and rear-passenger doors in vehicles targeting a variety of markets. The L99DZ70 is qualified to automotive standards and delivered in a 36-pin PowerSSO-36 package with enhanced thermal properties for high reliability in all automotive operating environments.

For more information, or details on the full range of STMicroelectronics products available from Anglia, please call +44 (0)1945 474747 or email info@anglia.com

Anglia Components

Integrated automotive IC from STMicroelectronics consolidates door-mounted drivers for cost, assembly, and reliability advantages