The TC7126A is a 3½ digit CMOS analog-to-digital converter (ADC) containing all the active components necessary to construct a 0.05% resolution measurement system. Seven-segment decoders, digit and polarity drivers, voltage reference, and clock circuit are integrated on-chip. The TC7126A directly drives a liquid crystal display (LCD), and includes a backplane driver. A low-cost, high-resolution indicating meter requires only a display, four resistors, and four capacitors. The TC7126A's extremely low power drain and 9V battery operation make it ideal for portable applications. The TC7126A reduces linearity error to less than 1 count. 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 current and a 10¹² ohm input impedance. The 15 µVp-p noise performance guarantees a great reading, and the auto-zero cycle guarantees a zero display reading with a 0V input. The TC7126A features a precision, low-drift internal voltage reference and is functionally identical to the TC7126. A low-drift external reference is not normally required with the TC7126A.