GENERAL DESCRIPTION

The AD7631 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 AD7631 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 AD7631 features four different analog input ranges. Power is scaled linearly with throughput. Operation is specified from −40°C to +85°C.

FEATURES

Multiple pins/software-programmable input ranges

+5 V (10 V p-p), +10 V (20 V p-p), –5 V (20 V p-p),

–10 V (40 V p-p)

Pins or serial SPI-compatible input ranges/mode selection

Throughput: 250 kSPS

INL: –1.5 LSB typical, –2.5 LSB maximum (–9.5 ppm of FSR)

18-bit resolution with no missing codes

Dynamic range: 102.5 dB

SNR: 101 dB @ 2 kHz

THD: −112 dB @ 2 kHz

iCMOSfi process technology

5 V internal reference: typical drift 3 ppm/°C; TEMP output

No pipeline delay (SAR architecture)

Parallel (18-/16-/8-bit bus) and serial 5 V/3.3 V interface

SPI-/QSPI™-/MICROWIRE™-/DSP-compatible

Power dissipation

73 mW @ 250 kSPS

10 mW @ 1 kSPS

Pb-free, 48-lead LQFP and 48-lead LFCSP (7 mm × 7 mm)

APPLICATIONS

Process controls

High speed data acquisition

Digital signal processing

Spectrum analysis

ATE