Low power, single-rail level shifters employing power down signal from output power domain and a method of converting a data signal between power domains

A voltage level shifter, comprising:

• an input circuit configured to receive a data signal from an input power domain and a power down signal from an output power domain;
• and
• a transition circuit coupled to said input circuit and configured to receive said data signal and an inverted signal of said power down signal, wherein said input circuit and said transition circuit are both configured to connect to an output supply voltage of said output power domain as a power source, said input circuit including a first switch configured to receive said output supply voltage and a second switch configured to receive an input supply voltage of said input power domain to control operation of said second switch, wherein operation of said first switch is based on a voltage difference between said input supply voltage and said output supply voltage.