Oscillator

CS

SCLK

SDI

SDO

PGA

1 M:

OVP

1 M:

OVP

2nd-Order

LPF

ADC

Driver

AIN_P

AIN_GND

16-Bit

SAR ADC

4.096-V

Reference

REFGND

DGND

AGND

DVDD

AVDD

ADS8681

Digital

Logic

and

Interface

REFIO

REFCAP

Product

Folder

Sample &

Buy

Technical

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Tools &

Software

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCT PREVIEW Information. Product in design phase of

development. Subject to change or discontinuance without notice.

ADS8681

SBAS633 – FEBRUARY 2016

ADS8681 16-Bit, 1-MSPS, Single-Supply, SAR ADC Data Acquisition System

with Programmable, Bipolar Input Ranges

1

1 Features

1

•

16-Bit ADC with Integrated Analog Front-End

•

Software Programmable Input Ranges:

–

Bipolar Ranges: ±12.288 V, ±10.24 V,

±6.144 V, ±5.12 V and ±2.56 V

–

Unipolar Ranges: 0 V–12.288 V, 0 V–10.24 V,

0 V–6.144 V and 0 V–5.12 V

•

5-V Analog Supply: 1.65-V to 5-V I/O Supply

•

Constant Resistive Input Impedance

≥ 1 MΩ

•

Input Overvoltage Protection: Up to ±20 V

•

On-Chip 4.096-V Reference with Low Drift

•

Excellent Performance:

–

1-MSPS Aggregate Throughput

–

DNL: ±0.5 LSB; INL: ±0.75 LSB

–

SNR: 90 dB; THD: –102 dB

•

multiSPI™ Interface with Daisy-Chain

•

Industrial Temperature Range: –40°C to +125°C

•

Packages:

–

16-Pin TSSOP (5.0 mm × 4.4 mm)

–

16-Pin WQFN-16 package (4.0 mm × 4.0 mm)

2 Applications

•

Channel-Isolated PLC Analog Input Modules

•

Test and Measurement

•

Battery Pack Monitoring

3 Description

The ADS8681 is an integrated data acquisition

system based on a 16-bit successive approximation

(SAR) analog-to-digital converter (ADC), operating at

a throughput of 1 -MSPS. The device features a high-

precision SAR ADC, integrated analog front-end input

driver circuit, overvoltage protection circuit up to

±20 V, and an on-chip 4.096-V reference with

extremely low temperature drift. Operating on a single

5-V analog supply, the ADS8681 can support true

bipolar input ranges of ±12.288 V, ±6.144 V,

±10.24 V, ±5.12 V, and ±2.56 V, as well as unipolar

input ranges of 0 V to 12.288 V, 0 V to 10.24 V, 0 V

to 6.144 V, and 0 V to 5.12 V. The gain and offset

errors for the analog front end circuit are accurately

trimmed within the specified values for each input

range to ensure high dc precision. The input range

selection is done by software programming of the

device internal registers. The device offers a high

resistive input impedance (

≥ 1 MΩ) irrespective of the

selected input range.

The ADS8681 offers an enhanced SPI-compatible

serial interface (multiSPI) to the digital host and also

supports daisy-chaining of multiple devices. The

digital supply can operate from 1.65 V to 5.25 V,

enabling direct interface to a wide range of host

controllers.

Device Information

PART NUMBER

PACKAGE

BODY SIZE (NOM)

ADS8681

TSSOP (16)

5.0 mm × 4.4 mm

WQFN (16)

4.0 mm × 4.0 mm

Block Diagram