FEATURES

18-bit resolution with no missing codes

Throughput: 250 kSPS

INL

±0.75 LSB typical

±1.5 LSB minimum/maximum at −40°C to +85°C

−2.7 LSB/+2 LSB minimum/maximum at −55°C to +105°C

Dynamic range: 102 dB typical

Oversampled dynamic range: 125 dB at 1 kSPS

Noise-free code resolution: 20 bits at 1 kSPS

Effective resolution: 22.7 bits at 1 kSPS

SINAD: 101 dB typical at fIN = 1 kHz, VREF = 5 V

THD: −125 dB typical at fIN = 1 kHz, VREF = 5 V

True differential analog input range: ±VREF

0 V to VREF with VREF up to VDD on both inputs

No pipeline delay

Single-supply 2.3 V to 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

Optional busy indicator feature

Power dissipation

1.35 mW at VDD = 2.5 V, 100 kSPS throughput

4.24 mW at VDD = 5 V, 100 kSPS throughput

1.4 μW at VDD = 2.5 V, 100 SPS throughput

Standby current: 1 nA

10-lead MSOP

Pin-for-pin compatible with the18-bit AD7690 and 16-bit

AD7693, AD7688, and AD7687

ENHANCED PRODUCT FEATURES

Supports defense and aerospace applications (AQEC standard)

Military temperature range: −55°C to +105°C

Controlled manufacturing baseline

One assembly/test site

One fabrication site

Enhanced product change notification

Qualification data available on request

APPLICATIONS

Battery-powered equipment

Data acquisitions

Seismic data acquisition systems

Instrumentation

Medical instruments

GENERAL DESCRIPTION

The AD7691-EP is an 18-bit, charge redistribution, successive

approximation, analog-to-digital converter (ADC) that operates

from a single power supply, VDD, between 2.3 V and 5 V. It

contains a low power, high speed, 18-bit sampling ADC with

no missing codes, an internal conversion clock, and a versatile

serial interface port. On the CNV rising edge, it samples the

voltage difference between the IN+ and IN− pins. The voltages

on these pins swing in opposite phases between 0 V and REF.

The reference voltage, REF, is applied externally and can be set

up to the supply voltage.

The power of the AD7691-EP scales linearly with throughput.

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, or 5 V logic, using the separate VIO supply.

The AD7691-EP is housed in a 10-lead MSOP with operation

specified from −55°C to +105°C. Additional application and

technical information can be found in the AD7691 data sheet.