Method and apparatus for power domain isolation during power down

Abstract

An apparatus and method for isolating circuitry from one power domain from that of another power domain prior to performing a power down operation is disclosed. In one embodiment, circuitry in a first power domain is coupled to receive signals based on outputs from circuitry in a second power domain. The signals may be conveyed to the circuitry in the first power domain via passgate circuits. When powering down the circuitry of the first and second power domains, a control circuit may first deactivate the passgate circuits in order to isolate the circuitry of the first power domain from that of the second power domain. The circuitry in the second power domain may be powered off subsequent to deactivating the passgate circuits. The circuitry in the first power domain may be powered off subsequent to powering off the circuitry in the second power domain.

Dependencies are inferred from the claim text.