Accelerometer adds durability to secure remote key fobs

July 10, 2019 //By Christoph Hammerschmidt
Accelerometer adds durability to secure remote key fobs
Life is hard for Passive Keyless Entry (PKE) car key fobs: Throughout their lifetime, they suffer drops, bumps and scrapes. A new accelerometer adds robustness to these devices. Plus, its low power consumption enables motion awareness functions for better theft resistance.

PKE radio fobs listen continuously for an “unlock” request coming from the vehicle when it is touched. They then send a command to unlock the vehicle. Thieves can force a fob that is out of range – it could be placed on a table in the owner’s house -- to send an unlock command by relaying the request via an intermediate transmitter, and hence gain access and steal the vehicle.

Enhanced with an accelerometer, fobs can ignore malicious relayed transmissions by powering down the receiver when not moving and out of range. The radio wakes only when movement is detected at close range as the owner approaches the vehicle. In addition, deactivating the receiver during idle periods helps extend battery life.

Unlike some other accelerometers positioned for PKE, STMicroelectronics’ AIS2DW12 passes severe industry shock testing. Hence vehicle owners can enjoy greater security without taking extra care of a fragile fob, and with longer battery life as a bonus.

Leveraging the dedicated internal engine for efficient movement and orientation detection, the operating current of just 380nA at 1.6Hz is at least twice as good as alternative devices, enhancing battery-energy savings. The AIS2DW12 operates from 1.8V DC and can be powered from a single lithium cell, producing a digital output with full-scale range up to 4g.

The AIS2DW12 is AEC-Q100 certified and compliant with automotive Product Part Approval Process (PPAP) Level-3. It is available now in a 2mm x 2mm x 1mm 12-pad Land-Grid Array (LGA) package from $1.375 for orders of 1000 pieces.

More information:   www.st.com/ais2dw12-pr 

 


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