The AD7984 is an 18-bit, successive approximation, analog-to-digital converter (ADC) that operates from a single power supply, VDD. It contains a low power, high speed, 18-bit sampling ADC and a versatile serial interface port. On the CNV rising edge, the AD7984 samples the voltage difference between the IN+ and IN− pins. The voltages on these pins usually swing in opposite phases between 0 V and VREF. The reference voltage, REF, is applied externally and can be set independent of the supply voltage, VDD.
The SPI-compatible serial interface also features the ability, using the SDI input, to daisy-chain several ADCs on a single 3-wire bus and provides an optional busy indicator. It is compatible with 1.8 V, 2.5 V, 3 V, and 5 V logic, using the separate VIO supply.
The AD7984 is available in a 10-lead MSOP or a 10-lead QFN (LFCSP) with operation specified from −40°C to +85°C.
**Applications**
Battery-powered equipment
Data acquisition systems
Medical instruments
Seismic data acquisition systems
### Features and Benefits
18-bit resolution with no missing codes
Throughput: 1.33 MSPS
Low power dissipation: 10.5 mW at 1.33 MSPS
INL: ±2.25 LSB maximum
Dynamic range: 99.7 dB typical
True differential analog input range: ±VREF 0 V to VREF
with VREF between 2.9 V to 5.0 V
Allows use of any input range
Easy to drive with the ADA4941
No pipeline delay
Single-supply 2.5 V operation with 1.8 V/2.5 V/3 V/5 V logic interface
Serial interface SPI-/QSPI™-/MICROWIRE™-/DSP-compatible
Ability to daisy-chain multiple ADCs and busy indicator
10-lead MSOP (MSOP-8 size) and 10-lead 3 mm × 3 mm QFN (LFCSP), SOT-23 size
