16-Bit, 8-Channel,

Preliminary Technical Data

AD7689

Rev. PrC

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FEATURES

16-bit resolution with no missing codes

8-channel multiplexer with:

Unipolar single ended or

Differential (GND sense)/Bipolar inputs

Throughput: 250 kSPS

INL/DNL: ±0.6 LSB typical

Dynamic range: 93.5 dB

SINAD: 92.5 dB @ 20 kHz

THD: −100 dB @ 20 kHz

Analog input range:

Reference:

Internal selectable 2.5 V/4.096 V or

External buffered (up to 4.096 V)

External (up to VDD)

Internal temperature sensor

Channel sequencer, selectable 1-pole filter, BUSY indicator

No pipeline delay, SAR architecture

Single-supply 2.7V – 5.5 V operation with

1.8 V to 5 V logic interface

Serial interface SPI®/QSPI™/MICROWIRE™/DSP compatible

Power dissipation:

6 mW @ 5 V/100 kSPS

Standby current: 1 nA

20-lead 4 mm × 4 mm LFCSP package

APPLICATIONS

Battery-powered equipment

Medical instruments

Mobile communications

Personal digital assitants

Data acquisition

Seismic data acquisition systems

Instrumentation

Process Control

FUNCTIONAL BLOCK DIAGRAM

AD7689

REF

GND

VDD

VIO

DIN

SCK

SDO

CNV

1.8V to

VDD

2.7V to 5V

Sequencer

SPI Serial

Interface

MUX

16-Bit SAR

ADC

Band Gap

REF

Temp

Sensor

REFIN

IN0

IN1

IN4

IN5

IN6

IN7

IN3

IN2

COM

0.5V to VDD

22

μF

1-Pole

LPF

0.5V to 4.096V

0.1

μF

Figure 1.

Table 1. Multichannel14-/16-Bit PulSAR ADC

Type

Channels

250

kSPS

500

kSPS

ADC

Driver

14-Bit

8

AD7949

ADA4841-x

16-Bit

4

AD7682

ADA4841-x

16-Bit

8

AD7689

AD7699

ADA4841-x

GENERAL DESCRIPTION

The AD7689 is an 8-channel 16-bit, charge redistribution

successive approximation register (SAR), analog-to-digital

converter (ADC) that operates from a single power supply, VDD.

The AD7689 contains all of the components for use in a multi-

channel, low power, data acquisition system including: a true 16-

bit SAR ADC with no missing codes; an 8-channel, low crosstalk

multiplexer useful for configuring the inputs as single ended (with

or without ground sense), differential or bipolar; an internal low

drift reference (selectable 2.5V or 4.096V) and buffer; a

temperature sensor; a selectable 1-pole filter; and a sequencer

useful when channels are continuously scanned in order.

The AD7689 uses a simple SPI interface for writing to the

configuration register and receiving conversion results. The SPI

interface uses a separate supply, VIO, which is set to the host logic

level.

Power dissipation scales with throughput.

The AD7689 is housed in a tiny 20-lead LFCSP with operation

specified from −40°C to +85°C.