16-bit, 500-kSPS, 8-channel, single-supply SAR ADC with bipolar input ranges


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 open-in-new Find other Precision ADCs (<=10MSPS)

Package | Pins | Size

TSSOP (DBT) 38 43 mm² 9.7 x 4.4 open-in-new Find other Precision ADCs (<=10MSPS)


  • 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)
open-in-new Find other Precision ADCs (<=10MSPS)


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) Apr. 21, 2015
Application note Circuit for detecting input floating on ADS8681 ADC Mar. 31, 2021
User guide ADS8688EVM-PDK Evaluation Module (Rev. C) Mar. 17, 2021
Application note Reducing Phase Delay by Averaging on ADS8686S with Burst Sequencer Mode Jan. 11, 2021
Application note Circuit for protecting ADC with TVS diode and PTC fuse Aug. 03, 2020
Application note Input protection for high-voltage ADC circuit with TVS diode Jun. 26, 2019
Application note Circuit to increase input range on an integrated analog front end (AFE) SAR ADC (Rev. A) Mar. 08, 2019
Application note Reducing effects of external RC filter circuit on gain and drift error (Rev. A) Jan. 18, 2019
Application note High common-mode differential input voltage to ±10-V ADC input circuit Dec. 20, 2018
Application note Extending Input Voltage Range and Understanding Associated Errors for ADC With I Nov. 09, 2018
Technical article Improving sensor DAQ performance using the PRU-ICSS for grid protection and control Oct. 09, 2018
Technical article Interfacing multiple ADCs to a single processor for grid protection and control Sep. 13, 2018
Technical article Analog interfacing for grid infrastructure with Sitara processors Feb. 15, 2018
Selection guide TI Components for Aerospace and Defense Guide (Rev. E) Mar. 22, 2017
White paper Voltage-reference impact on total harmonic distortion Aug. 01, 2016
More literature SAR ADCs for PLC Applications Feb. 11, 2016
Technical article Smart power for smart cities: why time synchronization is essential – part 2 May 14, 2015
User guide Phase-Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation (Rev. B) Mar. 12, 2015

Design & development

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

Hardware development

document-generic User guide
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 (PHI (...)
  • Includes support circuitry as a design example to match ADC performance.
  • Serial interface header for easy connection to SDCC Controller Card.
  • Integrated 4.096V voltage reference.
  • Bipolar (±10.24 V, ±5,12 V, ±2.56 V ) or unipolar (0 to 10.24V, 0 to 5.12V) input ranges for each channel.
  • Onboard 2nd Order (...)

Software development

ADS8688 Linux® driver
ADS8688SW-LINUX 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 (...)

Design tools & simulation

SBAM199.ZIP (37 KB) - IBIS Model
SBAM201.ZIP (1597 KB) - TINA-TI Reference Design
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — 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 (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)
SPICE-based analog simulation program
TINA-TI 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 (...)
document-generic User guide
Analog-to-digital converter (ADC) input driver design tool supporting multiple input types
ADC-INPUT-CALC 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 transformer-coupled (...)
Analog engineer's calculator
ANALOG-ENGINEER-CALC — 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 (...)
  • Expedites circuit design with analog-to-digital converters (ADCs) and digital-to-analog converters (DACs)
    • Noise calculations
    • Common unit translation
  • Solves common amplifier circuit design problems
    • Gain selections using standard resistors
    • Filter configurations
    • Total noise for common amplifier configurations
  • (...)
SBAC224.ZIP (59 KB)

Reference designs

High accuracy analog input module reference design with 16-bit 1-MSPS dual simultaneous-sampling ADC
TIDA-01576 — 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 (...)
document-generic Schematic document-generic User guide
Flexible Interface (PRU-ICSS) Reference Design for Simultaneous, Coherent DAQ Using Multiple ADCs
TIDA-01555 — 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 (...)
document-generic Schematic document-generic User guide
Isolated, High-Accuracy Analog Input Module Reference Design Using 16-Bit ADC and Digital Isolator
TIDA-01214 — 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 performance (...)
document-generic Schematic document-generic User guide
Analog Front End (AFE) for Merging Units and Multi-Function Protection Relays Reference Design
TIDA-00307 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 (...)
document-generic Schematic document-generic User guide
Voltage & Current (Power) Measurement AFE for mV Output Sensor Interface to SAR ADC Reference Design
TIDA-00493 The TIDA-00493 TI 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 (...)
document-generic Schematic document-generic User guide
16-Bit Analog Mixed Input and Output Module for Programmable Logic Controller (PLC) Reference Design
TIDA-00170 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 (...)
document-generic Schematic document-generic User guide
SPI Master with Signal Path Delay Compensation Reference Design
TIDEP0033 The Programmable Real-time unit within the Industrial Communication Subsystem (PRU-ICSS) enables customers to support real-time critical applications without using FPGAs, CPLDs or ASICs.
This TI design describes the implementation of the SPI master protocol with signal path delay compensation on (...)
document-generic Schematic document-generic User guide
Single Supply Analog Input Module Reference Design with 16-Bit, 8-Channel ADC for PLC
TIPD166 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 (...)
document-generic Schematic document-generic User guide
Phase Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation Reference Design
TIPD167 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, (...)
document-generic Schematic document-generic User guide

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