Product details

Resolution (Bits) 16 Number of input channels 8 Sample rate (Max) (kSPS) 500 Interface type SPI Architecture SAR Input type Single-Ended Multi-channel configuration Multiplexed Rating Catalog Reference mode Ext, Int Input range (Max) (V) 10.24 Input range (Min) (V) -10.24 Features Daisy-Chainable, Oscillator, Over-Voltage Protection, PGA Operating temperature range (C) -40 to 125 Power consumption (Typ) (mW) 65 Analog voltage AVDD (Min) (V) 4.75 SNR (dB) 92 Analog voltage AVDD (Max) (V) 5.25 INL (Max) (+/-LSB) 2 Digital supply (Min) (V) 1.65 Digital supply (Max) (V) 5.25
Resolution (Bits) 16 Number of input channels 8 Sample rate (Max) (kSPS) 500 Interface type SPI Architecture SAR Input type Single-Ended Multi-channel configuration Multiplexed Rating Catalog Reference mode Ext, Int Input range (Max) (V) 10.24 Input range (Min) (V) -10.24 Features Daisy-Chainable, Oscillator, Over-Voltage Protection, PGA Operating temperature range (C) -40 to 125 Power consumption (Typ) (mW) 65 Analog voltage AVDD (Min) (V) 4.75 SNR (dB) 92 Analog voltage AVDD (Max) (V) 5.25 INL (Max) (+/-LSB) 2 Digital supply (Min) (V) 1.65 Digital supply (Max) (V) 5.25
TSSOP (DBT) 38 43 mm² 9.7 x 4.4
  • 16-Bit ADC with Integrated Analog Front-End
  • 4-, 8-Channel MUX with Auto and Manual Scan
  • Channel-Independent Programmable Input Ranges:
    • Bipolar: ±10.24 V, ±5.12 V, and ±2.56 V
    • Unipolar: 10.24 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:
    • 500-kSPS Aggregate Throughput
    • DNL: ±0.5 LSB; INL: ±0.75 LSB
    • Low Drift for Gain Error and Offset
    • SNR: 92 dB; THD: –102 dB
    • Low Power: 65 mW
  • AUX Input → Direct Connection to ADC Inputs
  • SPI™-Compatible Interface with Daisy-Chain
  • –40°C to 125°C Industrial Temperature Range
  • TSSOP-38 Package (9.7 mm × 4.4 mm)
  • 16-Bit ADC with Integrated Analog Front-End
  • 4-, 8-Channel MUX with Auto and Manual Scan
  • Channel-Independent Programmable Input Ranges:
    • Bipolar: ±10.24 V, ±5.12 V, and ±2.56 V
    • Unipolar: 10.24 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:
    • 500-kSPS Aggregate Throughput
    • DNL: ±0.5 LSB; INL: ±0.75 LSB
    • Low Drift for Gain Error and Offset
    • SNR: 92 dB; THD: –102 dB
    • Low Power: 65 mW
  • AUX Input → Direct Connection to ADC Inputs
  • SPI™-Compatible Interface with Daisy-Chain
  • –40°C to 125°C Industrial Temperature Range
  • TSSOP-38 Package (9.7 mm × 4.4 mm)

The ADS8684 and ADS8688 are 4- and 8-channel, integrated data acquisition systems based on a 16-bit successive approximation (SAR) analog-to-digital converter (ADC), operating at a throughput of 500 kSPS. The devices feature integrated analog front-end circuitry for each input channel with overvoltage protection up to ±20 V, a 4- or 8-channel multiplexer with automatic and manual scanning modes, and an on-chip, 4.096-V reference with low temperature drift. Operating on a single 5-V analog supply, each input channel on the devices can support true bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, as well as unipolar input ranges of 0 V to 10.24 V and 0 V to 5.12 V. The gain of the analog front-end for all input ranges is accurately trimmed to ensure a high dc precision. The input range selection is software-programmable and independent for each channel. The devices offer a 1-MΩ constant resistive input impedance irrespective of the selected input range.

The ADS8684 and ADS8688 offer a simple SPI-compatible serial interface to the digital host and also support daisy-chaining of multiple devices. The digital supply operates from 1.65 V to 5.25 V, enabling direct interface to a wide range of host controllers.

The ADS8684 and ADS8688 are 4- and 8-channel, integrated data acquisition systems based on a 16-bit successive approximation (SAR) analog-to-digital converter (ADC), operating at a throughput of 500 kSPS. The devices feature integrated analog front-end circuitry for each input channel with overvoltage protection up to ±20 V, a 4- or 8-channel multiplexer with automatic and manual scanning modes, and an on-chip, 4.096-V reference with low temperature drift. Operating on a single 5-V analog supply, each input channel on the devices can support true bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, as well as unipolar input ranges of 0 V to 10.24 V and 0 V to 5.12 V. The gain of the analog front-end for all input ranges is accurately trimmed to ensure a high dc precision. The input range selection is software-programmable and independent for each channel. The devices offer a 1-MΩ constant resistive input impedance irrespective of the selected input range.

The ADS8684 and ADS8688 offer a simple SPI-compatible serial interface to the digital host and also support daisy-chaining of multiple devices. The digital supply operates from 1.65 V to 5.25 V, enabling direct interface to a wide range of host controllers.

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Technical documentation

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Type Title Date
* Data sheet ADS868x 16-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with Bipolar Input Ranges datasheet (Rev. C) 21 Apr 2015
Application note Circuit for detecting input floating on ADS8681 ADC 31 Mar 2021
User guide ADS8688EVM-PDK Evaluation Module (Rev. C) 17 Mar 2021
Application note Reducing Phase Delay by Averaging on ADS8686S with Burst Sequencer Mode 11 Jan 2021
Application note Circuit for protecting ADC with TVS diode and PTC fuse 03 Aug 2020
Application note Input protection for high-voltage ADC circuit with TVS diode 26 Jun 2019
Application note Circuit to increase input range on an integrated analog front end (AFE) SAR ADC (Rev. A) 08 Mar 2019
Application note Reducing effects of external RC filter circuit on gain and drift error (Rev. A) 18 Jan 2019
Application note High common-mode differential input voltage to ±10-V ADC input circuit 20 Dec 2018
Application note Extending Input Voltage Range and Understanding Associated Errors for ADC With I 09 Nov 2018
Technical article Improving sensor DAQ performance using the PRU-ICSS for grid protection and control 09 Oct 2018
Technical article Interfacing multiple ADCs to a single processor for grid protection and control 13 Sep 2018
Technical article Analog interfacing for grid infrastructure with Sitara processors 15 Feb 2018
White paper Voltage-reference impact on total harmonic distortion 01 Aug 2016
More literature SAR ADCs for PLC Applications 11 Feb 2016
Technical article Smart power for smart cities: why time synchronization is essential – part 2 14 May 2015
User guide Phase-Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation (Rev. B) 12 Mar 2015

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

ADS8688EVM-PDK — ADS8688 16-bit, 500-kSPS, 8-channel, single-supply, SAR ADC EVM performance demonstration kit (PDK)

The ADS8688 evaluation module (EVM) performance demonstration kit (PDK) is an platform for evaluating the ADS8588 product. The ADS8688 is an 8-channel integrated data acquisition system based on a 16-Bit SAR ADC.

The evaluation kit includes the ADS8688 evaluation board, precision host interface (...)
Driver or library

ADS8688SW-LINUX — ADS8688 Linux® driver

The Linux driver supports the ADS868x 16-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with Bipolar Input Ranges. The Linux driver supports communication through the SPI bus and interfaces with the IIO sub-system.

 

Linux Mainline Status

Available in Linux Main line: Yes
Available through (...)

Simulation model

ADS8688 IBIS Model

SBAM199.ZIP (37 KB) - IBIS Model
Simulation model

ADS868x TINA Model

SBAM201.ZIP (1597 KB) - TINA-TI Reference Design
Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
Simulation tool

TINA-TI — SPICE-based analog simulation program

TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
Calculation tool

ADC-INPUT-CALC — Analog-to-digital converter (ADC) input driver design tool supporting multiple input types

ADC-INPUT-CALC is an online tool that provides support for designing the input buffer to an analog-to-digital converter (ADC). It offers 24 different op-amp based buffer circuits that can be used to drive an ADC input. The available topologies cover differential, single-ended and (...)
Calculation tool

ANALOG-ENGINEER-CALC — Analog engineer's calculator

The Analog Engineer’s Calculator is designed to speed up many of the repetitive calculations that analog circuit design engineers use on a regular basis. This PC-based tool provides a graphical interface with a list of various common calculations ranging from setting op-amp gain with feedback (...)
Gerber file

Source Files for SBAA337

SBAC224.ZIP (59 KB)
Reference designs

TIDA-01576 — High accuracy analog input module reference design with 16-bit 1-MSPS dual simultaneous-sampling ADC

This reference design accurately measures 16-channel AC voltage and current inputs using a precision 16-bit SAR ADC over a wide input range. This range covers protection and measurement requirements (including sampling requirements as per IEC 61850-9-2), which simplifies system design and improves (...)
Reference designs

TIDA-01555 — Flexible Interface (PRU-ICSS) Reference Design for Simultaneous, Coherent DAQ Using Multiple ADCs

This reference design showcases an interface implementation for connecting multiple high voltage bipolar input, 8-channel, mux-input SAR ADCs (6) with the Sitara Arm processors for expanding the number of input channels using Programmable Real-time Unit (PRU-ICSS). ADCs are configured for (...)
Reference designs

TIDA-01214 — Isolated, High-Accuracy Analog Input Module Reference Design Using 16-Bit ADC and Digital Isolator

This reference design provides accurate measurements of AC voltage and current inputs using a precision 16-bit SAR ADC over a wide input range, covering protection and measurement range (including sampling requirements of IEC 61850-9-2), simplifying system design and improving trip time (...)
Reference designs

TIDA-00307 — Analog Front End (AFE) for Merging Units and Multi-Function Protection Relays Reference Design

This solution addresses the front end needs of Merging Units where multiple measurement channels for current and voltage are required. This implementation is modular, allowing easy expansion of channels while at the same time keeping the connectivity to the processor minimal by using the SPI daisy (...)
Reference designs

TIDA-00170 — 16-Bit Analog Mixed Input and Output Module for Programmable Logic Controller (PLC) Reference Design

The TIDA-00170 is a reference design for industrial control Analog Mixed Input Output Modules. The design implements four channel analog input & two channel analog output. The analog input channels can measure all standard industrial voltages up to ±10V and current inputs up to 24mA. The (...)
Reference designs

TIDEP0033 — SPI Master with Signal Path Delay Compensation Reference Design

The Programmable Real-time Unit within the Industrial Communication Subsystem (PRU-ICSS) enables you to support real-time critical applications without using FPGAs, CPLDs or ASICs.
This reference design describes the implementation of the SPI master protocol with signal path delay compensation on (...)
Reference designs

TIPD166 — Single Supply Analog Input Module Reference Design with 16-Bit, 8-Channel ADC for PLC

This design is for a 16-bit, 8-channel analog input module for industrial programmable logic controller (PLC) systems. The circuit is realized with an 8-channel, 16-bit, successive-approximation-register (SAR), analog-to-digital converter (ADC) with an integrated precision reference and analog (...)
Reference designs

TIDA-00493 — Voltage & Current (Power) Measurement AFE for mV Output Sensor Interface to SAR ADC Reference Design

This reference design is a fixed-gain amplifier stage for measuring low-amplitude voltage and current inputs accurately over a wide dynamic range using SAR ADC for power measurement applications. Low-amplitude AC voltage from voltage dividers, current transformers or split-core current sensors with (...)
Reference designs

TIPD167 — Phase Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation Reference Design

This TI Verified Design provides the theory, component selection, TINA-TI simulations, Verification & Measurement Performance, Altium Schematics, PCB Layout for a Phase Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation.  The design uses a 16-bit, 8-Channel, 500ksps SAR ADC, (...)
Package Pins Download
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