Driver circuit for reducing the effects of disturbances on the duty cycle of a digital signal on a bus conductor

Abstract

An electronic circuit contains a driver circuit () with an output coupled to a digital communication conductor (), for driving changes of a potential at the digital communication conductor () to and from a digital signal level. The driver circuit () comprises a control circuit (), to generate selection signals that select increasingly stronger drive strengths and increasingly weaker drive strengths during changes to and from the digital level respectively. A controllable current supply circuit (), has a current control input coupled to the control circuit () for receiving the selection signals and a current supply output coupled to the digital communtication conductor (). A detector circuit () has an input coupled to the digital communtication conductor () and an output coupled to the control circuit (), and arranged to detect whether a potential at the digital communication conductor () has reached a required range. The control circuit () stores information about the drive strength that was selected when the detector circuit () indicated that the range was reached during the change to the digital level, and during the change it restores the drive strength to the last stored drive strength as a first step during the change away from the digital level.