GENERAL DESCRIPTION
The AD7903 is a dual 16-bit, successive approximation, analog to-digital converter (ADC) that operates from a single power supply, VDDx, per ADC. It contains two low power, high speed, 16-bit sampling ADCs and a versatile serial port interface (SPI). On the CNVx rising edge, the AD7903 samples the voltage difference between the INx+ and INx− pins. The voltages on these pins usually swing in opposite phases between 0 V and VREF. The externally applied reference voltage of the REFx pins (VREF) can be set independently from the supply voltage pins, VDDx. The power of the device scales linearly with throughput.
Using the SDIx inputs, the SPI-compatible serial interface can also daisy-chain multiple ADCs on a single 3-wire bus and provide an optional busy indicator. It is compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate VIOx supplies.
The AD7903 is available in a 20-lead QSOP package with operation specified from −40°C to +125°C.

FEATURES
   16-bit resolution with no missing codes
   Throughput: 1 MSPS
   Low power dissipation
      7.0 mW at 1 MSPS (VDD1 and VDD2 only)
      12.0 mW at 1 MSPS (total)
      140 µW at 10 kSPS
   INL: ±0.5 LSB typical, ±2.0 LSB maximum
   SINAD: 93.5 dB at 1 kHz
   THD: −112 dB at 1 kHz
   True differential analog input range: ±VREF
      0 V to VREF with VREF between 2.4 V to 5.1 V
      Allows use of any input range
      Easy to drive with the ADA4941-1
   No pipeline delay
   Single-supply 2.5 V operation with 1.8 V/2.5 V/3 V/5 V logic
      interface
   Serial port interface (SPI)/QSPI/MICROWIRE/DSP compatible
   20-lead QSOP package
   Wide operating temperature range: −40°C to +125°C

APPLICATIONS
   Battery-powered equipment
   Communications
   Automated test equipment (ATE)
   Data acquisition
   Medical instrumentation
   Redundant measurement
   Simultaneous sampling