These devices consist of four independent preci-sion voltage comparators with an offset voltage specifications as low as 2mV max for LM339A,LM239A and LM139A. All these comparators were designed specifically to operate from a sin-gle power supply aver a wide range of voltages. Operation from split power supplies is also possi-ble. These comparators also have a unique character-is tic in that the input common-mode voltage range includes ground even though operated from a sin-gle power supply voltage.