An analog-to-digital converter device capable of measuring inputs beyond a supply voltage including: an N bit analog-to-digital converter powered by a supply voltage and a reference voltage; a range resolution stage capable of receiving inputs at higher voltages than the supply voltage, providing an input to the analog-to-digital converter, and outputting a logic value of one for the N+1th bit in response to an input signal higher than the reference voltage; and a bootstrapped input multiplexer stage for connecting low voltage input signals directly to the analog-to-digital converter and for connecting input signals that can exceed the supply voltage to the range resolution stage.