Fairchild Semiconductor Corporation

Sean X Clark

James B Boomer

A bi-direction voltage level translating switch that connects a higher voltage circuit to a lower voltage circuit without using a direction signal disclosed. The drive circuit for the gate of an MOS switch acts to clamp the lower voltage side of the translating switch limiting the lower voltage to a level compatible with the lower voltage circuitry connected to the lower voltage side. A pull up circuit is connected to the higher voltage side of the switch and further defines a threshold lower than the lower voltage. When the signal reaches the threshold the pull up circuit pull the higher voltage side up to the higher voltage. Again the drive on the gate of the switch prevents that higher voltage from reaching the lower voltage side. When the lower voltage side drives, through an on switch, the higher voltage side low, the pull up circuit is designed to be overcome by the lower voltage drive circuitry so that the higher voltage side goes low. When the threshold is reached going low the pull up circuitry is disabled. In a preferred embodiment, the pull up circuit provides a low impedance connection to the higher voltage to quickly drive the higher voltage side high, but the low impedance is active for a given amount of time, wherein the pull up circuitry reverts to a high impedance. The circuit is suitable for operating in virtually all computer systems including networked communications, displays, data bases, and the like.

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North Yarmouth, ME, United States of America

Sean X Clark