Airbag controller with Safing MOSFET

Airbags have been a standard feature in passenger cars for over 20 years. Naturally these systems need to be extremely robust and reliable, regardless of whether it is just a single airbag for the driver and front passenger or a complete multi-stage airbag system offering a range of protection options (front, side, head, rollover and even pedestrian protection). A Safing MOSFET in series with firing circuit transistors provides cost-effective operational reliability, enabling breakage of the current circuit in case of incorrect operation due to malfunction or electrical noise.

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Block diagram

TVSdiode ESDdiode 25 V to 35 V 15 V to 20 V SafingMOSFET n squibs(n = 4 to 12) 12 V Airbagcontroller CAN/FlexRay BATTERY aaa-034790 DC/DCboostconverterIC Highlighted components are Nexperia focus products.

Transient Voltage Suppressors (TVS)

Reverse battery protection

DC-DC freewheeling

DC-DC boost low side switch

Safing MOSFET

ESD protection

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To view more information about the Nexperia components used in this application, please select a component above or click on a component (highlighted in blue) in the block diagram.

Design considerations

  • Traditional solutions to Airbag applications are being withdrawn from the market due to unsustainability
  • Enhanced SOA technology provides similar linear mode performance in a sustainable silicon technology
  • For pulsed linear mode applications, such as the Safing MOSFET in airbags, Nexperia’s ASFETs provide the required robustness while delivering significant board space savings (up to 84% with an LFPAK33 device) compared to traditional DPAK solutions
  • Airbag firing circuits need a stable voltage of 15 to 20 V, requiring a boost converter to step up the standard 12 V battery voltage to 25–35 V

Product listing

Transient Voltage Suppressors (TVS)

DC-DC freewheeling

ESD protection