Electronic Design

Infineon Power ICs Run Seatbelt Pretension System

Autoliv Inc. has selected Infineon as the sole supplier of power semiconductors for Autoliv’s next-generation seatbelt pretension systems, called Active Seatbelts. The system, currently being used in premium cars, uses an electrical motor and electronics to improve occupant safety by starting to tighten the seatbelt a few milliseconds before an imminent crash. The system uses a member of Infineon’s NovalithIC family to control and power the motor.

By removing slack before a crash, the seatbelts reduce the risk of rib fractures and other injuries. The pretension system can adapt the restraint force to the severity of the crash and weight of the occupant. The system also makes it easier to buckle up by softly tightening the seatbelt during buckling. Unlike pyrotechnic pretensioners, Active Seatbelts can be tightened to minimize the effects of G forces when driving through curves.

The NovalithIC combines three integrated circuits—two power chips and one logic circuit to control and monitor the power stage—in package of approximately 1 cm2. It uses the latest chip-by-chip as well as chip-on-chip technologies. The ICs provide a fully integrated high-current half-bridge for motor drive applications. They cut in half the space needed on a pc board to power electronics driving motor applications with currents of up to 70 A. Power output varies continuously depending on application need, a feature that slashes energy consumption by as much as 80%. The on-state resistance is typically just 16 mΩ, and the quiescent current just 7 µA.



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