The M9003 inductive proximity switch IC is used in non-contact proximity switches to detect the approach of metal objects. Featuring contactless construction and fully sealed housing, non-contact proximity switches deliver long service life, high reliability and fast response speed, and can replace mechanical limit switches. The IC also integrates reliability functions including load overcurrent protection, undervoltage protection and digital temperature compensation.
The chip works on the eddy current effect. An oscillator circuit composed of inductor and capacitor senses approaching metal objects. The oscillation remains stable when no metal target is near the inductor. When a metal object approaches, electromagnetic field energy from the oscillator circuit is absorbed, which reduces the amplitude of the oscillation loop or stops oscillation.