Logic level shifter with power on control

A logic level shifter for coupling a first logic circuit having a first voltage level power supply to a second logic circuit, said shifter and said second logic circuit having a second voltage level supply, with said second voltage level supply being present at a time when said first level voltage supply is not present, comprising:

• first input means for accepting a first logic signal wherein said first logic signal can vary from a reference voltage to said first voltage;
• second input means for accepting a complement of said first logic signal;
• first output means for providing a first output which can vary from said reference voltage to said second voltage;
• second output means for providing a second output which can vary from said reference voltage to said second voltage;
• means for maintaining said first output at said reference voltage and said second output at said second voltage during a first time period when said second voltage level power supply is present and said first level power supply is not present.

A logic level shifter for coupling a first logic circuit having a first voltage level power supply to a second logic circuit, said shifter and said second logic circuit having a second voltage level supply, comprising:

• first and second complementary transistors having a first common drain connection and coupled between a second voltage and ground;
• third and fourth complementary transistors having a second common drain connection and coupled between said second voltage and ground;
• a gate of said first transistor coupled to said second common drain connection;
• a gate of said fourth transistor coupled to said first common drain connection;
• a first input at a gate of said second transistor;
• a second input at a gate of said fourth transistor;
• a first output at said second common connection;
• a fifth transistor coupled between said second common connection and ground and having a gate coupled to said first common gate connection for maintaining said first output at ground when said second level voltage supply is on and said first level voltage supply is off.