Embodiments include a power isolation circuit. The power isolation circuit includes a logic block, a wrapper cell, an isolation cell, a test control unit, and/or a power control unit. The power control unit is coupled to the isolation cell and configured to receive a DFT internal core test mode control signal and a clamp control signal, and control the isolation cell dependent on the DFT internal core test mode control signal and the clamp control signal. Also disclosed is a multi-power domain multi-power isolation system, which includes a first power domain and a second power domain. The first power domain includes a logic block, wrapper cells, isolation cells, and a power control unit. The second power domain includes a logic block, wrapper cells, and level-shifter cells. The power control unit is coupled to the isolation cells. Additional power domains with similar characteristics can be included in the design.