An
overvoltage protection circuit arranged to sense removal of the
overvoltage condition. The protection circuit blocks current passing through a
pull up transistor of an output circuit to a high-potential supply rail during an
overvoltage condition applied at a common
bus. The protection circuit includes one protection
branch controlled by the potential at the
bus and powered by the high-potential supply rail of the output circuit to be protected. The protection circuit also includes a second protection
branch controlled by the high-potential supply rail and powered by the potential on the
bus. When an overvoltage condition occurs, the second
branch is activated and regulates an output from the first protection branch. That output
signal controls the control node of the
pull up transistor of the output circuit to be protected. The two protection branches are configured such that removal of the overvoltage condition causes a rapid changing of the state of the output of the first protection branch so that the operating condition of the
pull up transistor remains the same as it was prior to the overvoltage condition.