US Patent 7382064 Supply voltage identifier

A supply identifier takes precise decision on the range of the external supply to manage a proper internal supply to the core of the IC by controlling a regulator or a switch connected to external supply. This supply identifier defers the decision until everything that influences the decision settles after power-up, then makes a decision only once depending on the external supply range and switches itself off, keeping the decision stored, to avoid noise-induced wrong behavior and to reduce power consumption.