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