Bus-hold input circuit adapted for receiving input signals with voltage levels higher than the voltage supply thereof

摘要

An input circuit for an integrated circuit for interfacing an external signal line external to the integrated circuit includes first circuit means having an input that may be coupled to the signal line to provide a regenerated signal at their output, and second circuit means having an input coupled to receive the regenerated signal and driving the external signal line. The external signal line can thus be maintained at a predetermined logic level, even in the absence of any driving on the external signal line. Third circuit means are provided that are capable of providing to the second circuit means a supply voltage equal to the greater of a supply voltage of the integrated circuit to which the input circuit belongs, and the voltage existing on the external signal line.