Data Acquisition. ADS8681 Datasheet

ADS8681 Acquisition. Datasheet pdf. Equivalent

ADS8681 Datasheet
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Part ADS8681
Description SAR ADC Data Acquisition
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Texas Instruments ADS8681
Product
Folder
Order
Now
Technical
Documents
Tools &
Software
Support &
Community
Reference
Design
ADS8681, ADS8685, ADS8689
SBAS633C – FEBRUARY 2016 – REVISED OCTOBER 2018
ADS868x 16-Bit, High-Speed, Single-Supply, SAR ADC Data Acquisition System
With Programmable, Bipolar Input Ranges
1 Features
1 16-Bit ADC With Integrated Analog Front-End
• High Speed:
– ADS8681: 1 MSPS
– ADS8685: 500 kSPS
– ADS8689: 100 kSPS
• 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:
– DNL: ±0.4 LSB; INL: ±0.5 LSB
– SNR: 92 dB; THD: –107 dB
• ALARM High, Low Threshold
• multiSPI™ Interface With Daisy-Chain
• Extended Industrial Temperature Range:
–40°C to +125°C
2 Applications
• Channel-Isolated PLC Analog Input Modules
• Test and Measurement
• Battery Pack Monitoring
3 Description
The ADS8681, ADS8685, and ADS8689 belong to a
family of integrated data acquisition system based on
a successive approximation (SAR) analog-to-digital
converter (ADC). The devices feature a high-speed,
high-precision SAR ADC, integrated analog front-end
(AFE) input driver circuit, overvoltage protection
circuit up to ±20 V, and an on-chip 4.096-V reference
with extremely low temperature drift.
The devices operate on a single 5-V analog supply,
but 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 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 devices offer a high resistive input impedance
(1 MΩ) irrespective of the selected input range.
The multiSPI digital interface is backward-compatible
to the traditional SPI protocol. Additionally,
configurable features simplify interface to a wide
range of host controllers.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
ADS868x
TSSOP (16)
WQFN (16)
5.00 mm × 4.40 mm
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
AVDD
ADS868x
Block Diagram
DVDD
4.096-V
Reference
REFIO
REFCAP
AIN_P
AIN_GND
1 M:
1 M:
OVP
OVP
PGA
AGND
2nd-Order
LPF
ADC
Driver
VBIAS
Oscillator
DGND
16-Bit
SAR ADC
REFGND
Digital Logic
and Interface
CONVST/CS
SCLK
SDI
SDO
1
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. PRODUCTION DATA.



Texas Instruments ADS8681
ADS8681, ADS8685, ADS8689
SBAS633C – FEBRUARY 2016 – REVISED OCTOBER 2018
www.ti.com
Table of Contents
1 Features .................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Pin Configuration and Functions ......................... 4
6 Specifications......................................................... 6
6.1 Absolute Maximum Ratings ...................................... 6
6.2 ESD Ratings.............................................................. 6
6.3 Recommended Operating Conditions....................... 6
6.4 Thermal Information .................................................. 6
6.5 Electrical Characteristics........................................... 7
6.6 Timing Requirements: Conversion Cycle................ 11
6.7 Timing Requirements: Asynchronous Reset........... 11
6.8 Timing Requirements: SPI-Compatible Serial
Interface ................................................................... 11
6.9 Timing Requirements: Source-Synchronous Serial
Interface (External Clock) ........................................ 12
6.10 Timing Requirements: Source-Synchronous Serial
Interface (Internal Clock).......................................... 12
6.11 Typical Characteristics .......................................... 16
7 Detailed Description ............................................ 23
7.1 Overview ................................................................. 23
7.2 Functional Block Diagram ....................................... 23
7.3 Feature Description................................................. 24
7.4 Device Functional Modes........................................ 36
7.5 Programming........................................................... 41
7.6 Register Maps ......................................................... 49
8 Application and Implementation ........................ 57
8.1 Application Information............................................ 57
8.2 Typical Application ................................................. 57
9 Power Supply Recommendations...................... 61
9.1 Power Supply Decoupling ....................................... 61
9.2 Power Saving .......................................................... 61
10 Layout................................................................... 62
10.1 Layout Guidelines ................................................. 62
10.2 Layout Example .................................................... 63
11 Device and Documentation Support ................. 64
11.1 Documentation Support ........................................ 64
11.2 Related Links ........................................................ 64
11.3 Receiving Notification of Documentation Updates 64
11.4 Community Resources.......................................... 64
11.5 Trademarks ........................................................... 64
11.6 Electrostatic Discharge Caution ............................ 64
11.7 Glossary ................................................................ 65
12 Mechanical, Packaging, and Orderable
Information ........................................................... 65
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (December 2016) to Revision C
Page
• Deleted per channel from ALARM High, Low Threshold bullet in Features section.......................................................... 1
• Added pin 1 indicator to RUM pinout drawing ........................................................................................................................ 4
• Deleted offers a low impedance of 30 kΩ from footnotes 2 and 3 in Absolute Maximum Ratings table ............................... 6
• Changed test conditions of Input Overvoltage Protection Circuit, VOVP parameter ................................................................ 7
• Deleted multichannel reference from Overview section ....................................................................................................... 23
• Changed the input voltage range for each analog channel to the input voltage range in Analog Input Structure section .. 24
• Changed Input Overvoltage Protection Limits When AVDD = 5 V table name from Input Overvoltage Protection
Limits When AVDD = 5 V or Offers a Low Impedance of 30 kΩ.......................................................................................... 25
• Changed AVDD is floating with an impedance 30 kΩ to AVDD is floating in Input Protection Circuit section..................... 26
• Changed Input Overvoltage Protection Limits When AVDD = Floating table title from Input Overvoltage Protection
Limits When AVDD = Floating with Impedance 30 kΩ ......................................................................................................... 26
• Added footnotes to List of Input Commands table ............................................................................................................... 43
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 ..................................................................................................................................................................................... 7
2 Submit Documentation Feedback
Copyright © 2016–2018, Texas Instruments Incorporated
Product Folder Links: ADS8681 ADS8685 ADS8689



Texas Instruments ADS8681
www.ti.com
ADS8681, ADS8685, ADS8689
SBAS633C – FEBRUARY 2016 – REVISED OCTOBER 2018
• Changed Power-Supply Requirements sub-section parameter names in Electrical Characteristics table for clarity
(specification values did not change) ..................................................................................................................................... 9
• Changed conditions of Timing Requirements tables ........................................................................................................... 11
• Changed Typical Characteristics section: added maximum throughput to conditions statement and deleted
redundant plots for the ADS868x ........................................................................................................................................ 16
• Changed Input Alarm section: corrected alarm reset configuration in last two paragraphs and both images ..................... 35
• Added fifth paragraph of Multiple Devices: Daisy-Chain Topology section.......................................................................... 38
• Added RST (Falling Edge) to Device Functional States figure ............................................................................................ 39
• Changed bulleted list in Data Transfer Frame section pertaining to the end of the data transfer frame F .......................... 42
• Changed Output Data Word section..................................................................................................................................... 44
• Changed several value after reset notations from h to b throughout bit registers of the Register Maps section ............... 49
• Changed ALARM_H_TH_REG Register Field Descriptions table ...................................................................................... 56
• Changed ALARM_L_TH_REG Register Field Descriptions table ....................................................................................... 56
• Changed Application and Implementation section for clarity and improved description of device functionality ................. 57
• Changed first sentence of Power Saving section................................................................................................................. 61
Changes from Original (February 2016) to Revision A
Page
• Released to production .......................................................................................................................................................... 1
Copyright © 2016–2018, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADS8681 ADS8685 ADS8689
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