Abstract: An integrated circuit such as an application specific integrated circuit (ASIC) which has operational power supplies provided for different respective analog cores and digital logic and/or macros may be tested using on-chip power supplies, preferably comprising operational amplifiers connected as voltage followers and controlled by a band-gap voltage source or a voltage divider, drawing power from a single power supply to the chip which is generally provided in a standardized pin-out location. Disablement of respective operational amplifiers also provides electrical isolation of the respective cores during testing. A reduced pin-count is involved in the testing procedure since operational power supply connections can be open circuited or "tri-stated". On-chip power supplies for testing provides power while avoiding a need to provide low-noise power supplies and/or complex switching in a test system or to utilize custom front-end boards or both to provide power to arbitrary chip or package connections.