The TC7136 and TC7136A are low-power, 3-1/2 digit with liquid crystal display (LCD) drivers with analog-todigital converters. These devices incorporate an "integrator output zero" phase which guarantees overrange recovery. The performance of existing TC7126, TC7126A and ICL7126-based systems may be upgraded with minor changes to external, passive components. The TC7136A has an improved internal zener reference voltage circuit which maintains the analog common temperature drift to 35 ppm/C (typical) and 75 ppm/C (maximum). This represents an improvement of two to four times over similar 3-1/2 digit converters. The costly, spaceconsuming external reference source may be removed. The TC7136/A limits linearity error to less than 1 count on 200 mV or 2V full-scale ranges. Roll-over error -- the difference in readings for equal magnitude but opposite polarity input signals -- is below 1 count. High-impedance differential inputs offer 1 pA leakage currents and a 1012 input impedance. The differential reference input allows ratiometric measurements for ohms or bridge transducer measurements. The 15 VP-P noise performance guarantees a "rock solid" reading. The auto-zero cycle guarantees a zero display readout for a 0V input.