The Intersil HI7191 is a monolithic instrumentation, sigma delta A/D converter which operates from 5V supplies. Both the signal and reference inputs are fully differential for maximum flexibility and performance. An internal Programmable Gain Instrumentation Amplifier (PGIA) provides input gains from 1 to 128 eliminating the need for external pre-amplifiers. The ondemand converter auto-calibrate function is capable of removing offset and gain errors existing in external and internal circuitry. The on-board user programmable digital filter provides over -120dB of 60/50Hz noise rejection and allows fine tuning of resolution and conversion speed over a wide dynamic range. The HI7191 and HI7191 are functionally the same device so all discussion will refer to the HI7191 for simplicity.