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.