Operation limiting and power-dissipation cutting functionality as often referred to as \"Enable/disable\" and \"Power-down\" abilities. These functionalities may have quite distinct implementations in electronic circuits. Power-down provides power consumption reduction by shutting down parts or whole function block. This paper discusses possibilities of enable and power-down functionality implementation in HV SoI unity-gain buffers. Modifications of selected HV buffer structures are analyzed. Approaches of power-down, high input and output impedance functionality implementation are introduced and discussed.