To let it turn off when you're not using it. It uses an inertial sensor.
I'm not dounting it's possibly, but I'd be surprised if it's available without involving a Turing-complete computer.
I'm not sure if there is a single-chip solution (although I'd be a bit surprised if there isn't), but the fundamental circuit isn't that ambitious. Using a very low-end microcontroller is likely less expensive, though.