2

ADS8681, ADS8685, ADS8689

SBAS633B – FEBRUARY 2016 – REVISED DECEMBER 2016

www.ti.com

Product Folder Links: ADS8681 ADS8685 ADS8689

Submit Documentation Feedback

Copyright © 2016, Texas Instruments Incorporated

Table of Contents

1

Features .................................................................. 1

2

Applications ........................................................... 1

3

Description ............................................................. 1

4

Revision History..................................................... 2

5

Pin Configuration and Functions ......................... 4

6

Specifications......................................................... 5

6.1

Absolute Maximum Ratings ...................................... 5

6.2

ESD Ratings.............................................................. 5

6.3

Recommended Operating Conditions ....................... 5

6.4

Thermal Information .................................................. 5

6.5

Electrical Characteristics........................................... 6

6.6

Timing Requirements: Conversion Cycle................ 10

6.7

Timing Requirements: Asynchronous Reset........... 10

6.8

Timing Requirements: SPI-Compatible Serial

Interface ................................................................... 10

6.9

Timing Requirements: Source-Synchronous Serial

Interface (External Clock) ........................................ 11

6.10

Timing Requirements: Source-Synchronous Serial

Interface (Internal Clock).......................................... 11

6.11

Typical Characteristics .......................................... 15

7

Detailed Description ............................................ 22

7.1

Overview ................................................................. 22

7.2

Functional Block Diagram ....................................... 22

7.3

Feature Description................................................. 23

7.4

Device Functional Modes........................................ 35

7.5

Programming........................................................... 40

7.6

Register Maps ......................................................... 48

8

Application and Implementation ........................ 56

8.1

Application Information............................................ 56

8.2

Typical Application ................................................. 56

9

Power Supply Recommendations ...................... 60

9.1

Power Supply Decoupling ....................................... 60

9.2

Power Saving .......................................................... 60

10

Layout................................................................... 61

10.1

Layout Guidelines ................................................. 61

10.2

Layout Example .................................................... 62

11

Device and Documentation Support ................. 63

11.1

Documentation Support ........................................ 63

11.2

Related Links ........................................................ 63

11.3

Receiving Notification of Documentation Updates 63

11.4

Community Resources.......................................... 63

11.5

Trademarks ........................................................... 63

11.6

Electrostatic Discharge Caution ............................ 63

11.7

Glossary ................................................................ 64

12

Mechanical, Packaging, and Orderable

Information ........................................................... 64

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision A (March 2016) to Revision B

Page

•

Added ADS8685 and ADS8689 devices to document .......................................................................................................... 1

•

Changed Features bullets: added High Speed bullet, deleted Aggregate Throughput sub-bullet from Excellent

Performance bullet, added Extended to Industrial Temperature Range bullet, and deleted Packages bullet ....................... 1

•

Changed Description section ................................................................................................................................................. 1

•

Deleted Device Comparison Table ........................................................................................................................................ 4

•

Added maximum throughput to conditions statement of Electrical Characteristics table and all Timing Requirements

tables ..................................................................................................................................................................................... 6

•

Changed Power-Supply Requirements sub-section parameter names in Electrical Characteristics table for clarity

(specification values did not change) ..................................................................................................................................... 8

•

Changed conditions of Timing Requirements tables ........................................................................................................... 10

•

Changed Typical Characteristics section: added maximum throughput to conditions statement and deleted

redundant plots for the ADS868x ........................................................................................................................................ 15

•

Changed Input Alarm section: corrected alarm reset configuration in last two paragraphs and both images ..................... 34

•

Added fifth paragraph of Multiple Devices: Daisy-Chain Topology section.......................................................................... 37

•

Added RST (Falling Edge) to Device Functional States figure ............................................................................................ 38

•

Changed bulleted list in Data Transfer Frame section pertaining to the end of the data transfer frame F .......................... 41

•

Changed Output Data Word section..................................................................................................................................... 43

•

Changed several value after reset notations from h to b throughout bit registers of the Register Maps section ............... 48

•

Changed ALARM_H_TH_REG Register Field Descriptions table ...................................................................................... 55

•

Changed ALARM_L_TH_REG Register Field Descriptions table ....................................................................................... 55

•

Changed Application and Implementation section for clarity and improved description of device functionality ................. 56

•

Changed first sentence of Power Saving section................................................................................................................. 60