Patent ID: 6915459

Claim:
An apparatus for providing failsafe detection for a differential receiver that produces a bus activity indicator signal when receiving a differential data signal of sufficient amplitude ton transition through a first predetermined receiver threshold, said apparatus comprising: a window comparator having an input coupled to said differential receiver and operable to activate a failsafe signal when a transition below a second predetermined threshold occurs on said differential receiver, said second predetermined threshold being less than said first predetermined threshold; a timer coupled to said window comparator and having an input to receive said bus activity indicator signal and said failsafe signal, said timer operable for deactivating a timeout signal in response to each activation of said bus activity indicator signal and said failsafe signal, said timer further for activating said timeout signal if a predetermined period of time elapses since a most recent deactivation of said timeout signal; and a failsafe indicator gate coupled to said timer and said window comparator to receive said timeout signal and said failsafe signal, and having an output to set a flag when said failsafe signal and said timeout signal are both active.