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ADS8688A

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16-bit, 500kSPS 8-channel SAR ADC with bipolar inputs using 5V supply and low-drift VREF

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Data sheet

ADS8688A

ACTIVE
Data sheet Order now

Product details

Resolution (Bits) 16 Sample rate (max) (ksps) 500 Number of input channels 8 Interface type SPI Architecture SAR Input type Single-ended Multichannel configuration Multiplexed Rating Catalog Reference mode External, Internal Input voltage range (max) (V) 10.24 Input voltage 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 supply voltage (min) (V) 4.75 Analog supply voltage (max) (V) 5.25 SNR (dB) 92 Digital supply (min) (V) 1.65 Digital supply (max) (V) 5.25
Resolution (Bits) 16 Sample rate (max) (ksps) 500 Number of input channels 8 Interface type SPI Architecture SAR Input type Single-ended Multichannel configuration Multiplexed Rating Catalog Reference mode External, Internal Input voltage range (max) (V) 10.24 Input voltage 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 supply voltage (min) (V) 4.75 Analog supply voltage (max) (V) 5.25 SNR (dB) 92 Digital supply (min) (V) 1.65 Digital supply (max) (V) 5.25
TSSOP (DBT) 38 62.08 mm² 9.7 x 6.4
  • 16-Bit ADCs with Integrated Analog Front-End
  • 4-, 8-Channel MUX with Auto and Manual Scan
  • Channel-Independent Programmable Inputs:
    • ±10.24 V, ±5.12 V, ±2.56 V, ±1.28 V, ±0.64 V
    • 10.24 V, 5.12 V, 2.56 V, 1.28 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
  • ALARM → High and Low Thresholds per Channel
  • SPI™-Compatible Interface with Daisy-Chain
  • Industrial Temperature Range: –40°C to 125°C
  • TSSOP-38 Package (9.7 mm × 4.4 mm)
  • 16-Bit ADCs with Integrated Analog Front-End
  • 4-, 8-Channel MUX with Auto and Manual Scan
  • Channel-Independent Programmable Inputs:
    • ±10.24 V, ±5.12 V, ±2.56 V, ±1.28 V, ±0.64 V
    • 10.24 V, 5.12 V, 2.56 V, 1.28 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
  • ALARM → High and Low Thresholds per Channel
  • SPI™-Compatible Interface with Daisy-Chain
  • Industrial Temperature Range: –40°C to 125°C
  • TSSOP-38 Package (9.7 mm × 4.4 mm)

The ADS8684A and ADS8688A 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, ±2.56 V, ±1.28V and ±0.64V, as well as unipolar input ranges of 0 V to 10.24 V, 0 V to 5.12 V, 0 V to 2.56 V and 0 V to 1.28 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 ADS8684A and ADS8688A 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 ADS8684A and ADS8688A 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, ±2.56 V, ±1.28V and ±0.64V, as well as unipolar input ranges of 0 V to 10.24 V, 0 V to 5.12 V, 0 V to 2.56 V and 0 V to 1.28 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 ADS8684A and ADS8688A 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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* Data sheet ADS868xA 16-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with Bipolar Input Ranges datasheet PDF | HTML 14 Jul 2015
Application brief Precision ADCs in Servo Drives (Rev. A) PDF | HTML 29 Oct 2025
Circuit design High common-mode differential input voltage to ±10-V ADC input circuit (Rev. A) PDF | HTML 24 Sep 2024
Circuit design Input Protection for High-Voltage ADC Circuit with TVS Diode (Rev. A) PDF | HTML 02 May 2023
Application note EMC Compliance Testing for Precision ADC Systems (Rev. A) PDF | HTML 27 May 2022
Application note Circuit for detecting input floating on ADS8681 ADC PDF | HTML 31 Mar 2021
Application brief Supporting High Voltage Common Mode Using Difference Amplifier PDF | HTML 08 Mar 2021
Application brief Supporting High Voltage Common Mode Using Instrumentational Amplifier PDF | HTML 23 Feb 2021
Application note Reducing Phase Delay by Averaging on ADS8686S with Burst Sequencer Mode PDF | HTML 11 Jan 2021
Application brief 16-Bit 8-Channel PLC Analog Input Module with High Voltage (±150 V) Common Mode 27 Apr 2020
Application note Extending Input Voltage Range and Understanding Associated Errors for ADC With I 09 Nov 2018
White paper Voltage-reference impact on total harmonic distortion 01 Aug 2016
E-book Best of Baker's Best: Precision Data Converters -- SAR ADCs 21 May 2015
User guide Phase-Compensated 8-Ch Multiplexed Data Acquisition System for Power Automation (Rev. B) 12 Mar 2015

Design & development

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Simulation model

ADS8688 IBIS Model

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

ADS868x TINA Model

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

ANALOG-ENGINEER-CALC — PC software 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 operational-amplifier (...)

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Design tool

ADC-DAC-TO-VREF-SELECT-DESIGN-TOOL — The ADC-TO-VREF-SELECT tool enables the pairing of TI ADCs, DACs, and series voltage references.

The ADC-TO-VREF-SELECT tool enables the pairing of TI analog-to-digital converters (ADCs) and series voltage references. Users can select an ADC device and the desired reference voltage, and the tool will list up to two voltage reference recommendations.
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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 (...)
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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 (...)
User guide: PDF
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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 (...)
Design guide: PDF
Schematic: PDF
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 (...)
Design guide: PDF
Schematic: PDF
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TSSOP (DBT) 38 Ultra Librarian
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