Apparatus and method for preventing configurable system-on-a-chip integrated circuits from becoming I/O limited

摘要

An integrated circuit containing multiple modules coupled to a pad via a multiplexer. The modules are selectively coupled to the pad by the multiplexer to provide integrated circuit function flexibility with a limited number of pads. A multiplexer select signal determines which module or clock circuit is coupled by the multiplexer. A common buffer may be coupled between the multiplexer and the pad to save substrate space. An analog circuit may be coupled to the pad to provide a signal path minimizing signal distortion. The integrated circuit's clock may be coupled via the multiplexer to an off-substrate circuit. Selective module coupling improves the integrated circuit's testing speed, may salvage an integrated circuit containing a malfunctioning module, and provides for signal loopback during testing.