The AD7634 is an 18-bit charge redistribution successive approximation register (SAR), architecture analog-to- digital converter (ADC) fabricated on Analog Devices, Inc.’s iCMOS high voltage process. The device is configured through hardware or via a dedicated write-only serial configuration port for input range and operating mode. The AD7634 contains a high speed 18-bit sampling ADC, an internal conversion clock, an internal reference (and buffer), error correction circuits, and both serial and parallel system interface ports. A falling edge on CNVST samples the fully differential analog inputs on IN+ and IN?. The AD7634 features four different analog input ranges and three different sampling modes. Operation is specified from ?40°C to +85°C.