System for retaining state data

摘要

According to one embodiment, a system for retaining M bits of state data of an integrated circuit during power down includes M serially coupled scan flip flops divided into M/N groups, where the M scan flip flops are able to save/restore the M bits of state data. Each group contains a merged scan flip flop coupled to a series of scan flip flops. The merged scan flip flop in each of the groups is coupled to a respective read port of a memory unit, and a final scan flip flop in each of the groups is coupled to a respective write port of the memory unit. The system enables the memory unit to save the M bits of state data in N clock cycles. Each merged scan flip flop has a read select input that enables restoring of the state data into the M scan flip flops in N clock cycles.

主权项

1. A system comprising:
a plurality of flip flops containing state data of an integrated circuit, said plurality of flip flops being divided into groups, each of said groups containing a merged flip flop; said merged flip flop in each of said groups being coupled to a respective read port of a memory unit, said memory unit saving said state data in a power saving mode of said integrated circuit.