Multi-voltage I/O buffer clamping circuit

摘要

A buffer circuit for mixed voltage applications. The circuit is built from field effect transistors and is used to interface with multiple voltage levels. The circuit uses a protection transistor in which the gate is controlled by a logic circuit having the mixed voltages as inputs. It is particularly useful on CMOS semiconductor chips that interface with multiple voltage levels which are required to conform to a specification allowing voltage levels to be powered down.