Patent ID: 7710177

Claim:
A device, comprising: a storage circuit comprising: a data input; a first control input; a first voltage reference input coupled to a first voltage reference, the storage circuit configured to store first data when the first voltage reference is at a first level; an output configured to provide the first data based on a signal at the first control input; a retention circuit configured to store the first data when the first voltage reference is at a second level whose magnitude is lower than the magnitude of the first level, the retention circuit comprising: a data input coupled to the output of the storage circuit; a second control input configured to receive a first isolation signal, the retention circuit configured to store the first data in response to assertion of the isolation signal; an output to provide the first data; and a restoration circuit, comprising: a data input coupled to the output of the retention circuit; a third control input configured to receive the first isolation signal; and an output coupled to the output of the storage circuit, the restoration circuit configured to couple the data input of the restoration circuit to the output of the storage circuit when the isolation signal is asserted.