GENERAL DESCRIPTION
The AD7631/AD7634 is an18-bit, charge redistribution successive approximation register (SAR) architecture analog-to-digital 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 −40°C to +85°C.

FEATURES
   Multiple pins/software programmable input ranges:
      ±10V, ±5V, 10V, 5V
   iCMOS™ process technology
   Pins or serial SPI input ranges/mode selection
   Throughput:
      670kSPS (AD7634)
      250kSPS (AD7631)
   INL: ± 1.75 LSB (7± ppm of full scale)
   DNL: +2/-1 LSB
   18-bit resolution with no missing codes
   Dynamic range: 102.5 dB typical
   SNR: 101 dB typical
   THD: -122 dB typical
   5V internal reference: typical drift 7ppm/°C; TEMP output
   No pipeline delay (SAR architecture)
   Parallel (18, 16- or 8-bit bus) and serial 5 V/3.3 V interface
   SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible
   Power dissipation:
      190 mW @ 670kSPS
      75 mW @ 250kSPS
   Pb-free 48-lead LQFP and LFCSP (7x7mm) packages
   Pin compatible with other PulSAR ADCs

APPLICATIONS
   Process control
   High speed data acquisition
   Digital signal processing
   Spectrum analysis
   Instrumentation
   Communications