Level shifter with memory interfacing two supply domains

Abstract

A level-shifter circuit configured to transfer data between two voltage supply domains may eliminate crowbar current while simultaneously providing a valid output signal. The level-shifter circuit may transfer a data signal between the two voltage domains using a latch that is capable of maintaining its output level—based on the destination supply rail—to correspond to the same state to which the level of the input signal—based on the originating supply rail—corresponds, even when the originating supply is decreased to a zero-volt state, or to a voltage equivalent to a low state. During normal operation, when both power supplies are available, the signal at the output of the latch, and hence at the output of the level-shifter circuit may toggle to always track the input signal. Thus, the level of the signal at the output of the level-shifter may always represent the same state (e.g. binary value) as the level of the input signal, during normal operation and also when the originating power supply is powered down.