Circuit for testing power supplies in multiple power modes

A built-in self test (BIST) circuit for testing the status of a plurality of power supplies that operate in N power modes where N>1, of a system including a plurality of circuit blocks connected to respective ones of the plurality of power supplies, the BIST circuit comprising:

• a finite state machine (FSM) having at least two power mode states respectively corresponding to at least two of the N power modes, wherein the FSM sequentially enables the at least two power mode states in a predetermined order, and in each power mode state, outputs one or more power mode signals to the power supplies to enable the power supplies used in the corresponding power mode;
• a plurality of power monitors, each connected to a respective power input node of a respective one of the plurality of circuit blocks, wherein each power monitor outputs a monitor signal indicative of the voltage at the corresponding power input node when the power supply provided to the corresponding power input node is enabled;
• and
• a comparator that receives the monitor signals and compares the monitor signals with corresponding reference signals, and generates a set of status signals that respectively indicate whether the corresponding power supply and a connection with the corresponding power input node are operating correctly.