1. A programmable system-on-a-chip integrated circuit device comprising: a programmable logic block a digital input/output circuit block; a non-volatile memory block; an analog circuit block including an analog to digital converter; an analog input/output circuit block including at least one temperature-sensing circuit coupled to a first I/O pad and including a programmable voltage prescaling circuit; a programmable interconnect architecture including programmable elements and interconnect conductors, the programmable interconnect architecture configured to programmably connect inputs and outputs of the programmable logic block, the non-volatile memory block, the analog circuit block, the analog input/output circuit block, and the digital input/output circuit block to one another, a voltage reference circuit; an analog power supply circuit; at least one digital power supply circuit; a power-up control circuit configured to enable the programmable logic block, the digital input/output circuit block, the non-volatile memory block, the analog circuit block, and the analog input/output circuit block in a predetermined sequence during system startup.