The AD7631/AD7634 is an18-bit, charge redistribution successive approximation register (SAR) architecture analog-todigital converter (ADC) with programmable input ranges and mode selection via a dedicated write only serial interface (or by hardware pin-strapping). The device is fabricated on ADI's patented iCMOS high voltage process. The device contains a high speed 18-bit sampling ADC, an internal conversion clock, an internal reference (and buffer), and both serial and parallel system interface ports. Power consumption is automatically scaled with throughput (AD7634 in Impulse mode), making it ideal for battery-powered applications. It is available in Pb-free, 48-lead packages with operation specified from -40C to +85C.