Acquisition System. ADS8689 Datasheet

ADS8689 Datasheet PDF


Part Number

ADS8689

Description

SAR ADC Data Acquisition System

Manufacture

etcTI

Total Page 30 Pages
Datasheet
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ADS8689
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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.

ADS8689
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
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Copyright © 2016–2018, Texas Instruments Incorporated
Product Folder Links: ADS8681 ADS8685 ADS8689





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