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ADS8681

ACTIVE

16-bit, 1MSPS 1-ch SAR ADC with programmable (±12V, ±10V, ±6V, ±5V, ±2.5V) input ranges on 5V supply

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Data sheet

ADS8681

ACTIVE
Data sheet Order now

Product details

Resolution (Bits) 16 Sample rate (max) (ksps) 1000 Number of input channels 1 Interface type Enhanced SPI, SPI Architecture SAR Input type Single-ended Rating Catalog Reference mode External, Internal Input voltage range (max) (V) 12.288 Input voltage range (min) (V) -12.288 Features Oscillator, Over-Voltage Protection, PGA Operating temperature range (°C) -40 to 125 Power consumption (typ) (mW) 42 Analog supply voltage (min) (V) 4.75 Analog supply voltage (max) (V) 5.25 SNR (dB) 90.5 Digital supply (min) (V) 1.65 Digital supply (max) (V) 5.25
Resolution (Bits) 16 Sample rate (max) (ksps) 1000 Number of input channels 1 Interface type Enhanced SPI, SPI Architecture SAR Input type Single-ended Rating Catalog Reference mode External, Internal Input voltage range (max) (V) 12.288 Input voltage range (min) (V) -12.288 Features Oscillator, Over-Voltage Protection, PGA Operating temperature range (°C) -40 to 125 Power consumption (typ) (mW) 42 Analog supply voltage (min) (V) 4.75 Analog supply voltage (max) (V) 5.25 SNR (dB) 90.5 Digital supply (min) (V) 1.65 Digital supply (max) (V) 5.25
TSSOP (PW) 16 32 mm² 5 x 6.4 WQFN (RUM) 16 16 mm² 4 x 4
  • 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
  • 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

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.

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.
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Pin-for-pin with same functionality to the compared device
ADS8685 ACTIVE 16-Bit, 500-kSPS, 1-Ch SAR ADC with programmable (±12/±10/±6/±5/±2.5V) input ranges on +5V supply 500 kSPS sampling rate
ADS8689 ACTIVE 16-Bit, 100-kSPS, 1-Ch SAR ADC with programmable (±12/±10/±6/±5/±2.5V) input ranges on +5V supply 100 kSPS sampling rate
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ADS8681W ACTIVE 16-bit, 1MSPS, one-channel, wide bandwidth SAR ADC with programmable input ranges on +5V supply 100 kSPS with wide input signal bandwidth capability

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* Data sheet ADS868x 16-Bit, High-Speed, Single-Supply, SAR ADC Data Acquisition System With Programmable, Bipolar Input Ranges datasheet (Rev. E) PDF | HTML 15 Aug 2022
Application brief Precision ADCs in Servo Drives (Rev. A) PDF | HTML 29 Oct 2025
Circuit design Input Protection for High-Voltage ADC Circuit with TVS Diode (Rev. A) PDF | HTML 02 May 2023
Product overview Bridge Sensor Solution (Rev. A) PDF | HTML 27 Jan 2023
Product overview PLC Analog Input Front-End Architectures PDF | HTML 31 Jul 2022
Application note Cost-Optimized, High-Performance Front-End Design for Analog Input Modules PDF | HTML 22 Jun 2022
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
Circuit design Circuit for protecting ADC with TVS diode and PTC fuse 03 Aug 2020
Application note Extending Input Voltage Range and Understanding Associated Errors for ADC With I 09 Nov 2018
White paper Fully integrated signal and power isolation – applications and benefits 10 Feb 2017
White paper Enabling Faster, Smarter, and More Robust Solutions for SAR ADSx With multiSPI 08 Nov 2016
More literature ADS8681EVM-PDK Quick Start Guide 04 Aug 2016
White paper Voltage-reference impact on total harmonic distortion 01 Aug 2016

Design & development

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

Evaluation board

PSIEVM — Precision signal injector (PSI) evaluation module for testing ADC performance

The precision signal injector (PSI) is a platform for evaluating the performance of successive-approximation register (SAR) analog-to-digital converters (ADCs). The board provides a low-distortion, low-noise, 2-kHz input signal for driving the input of the ADC, and pairs with most of the (...)

User guide: PDF
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Simulation model

ADS8681 IBIS Model

SBAM268.ZIP (36 KB) - IBIS Model
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Simulation model

ADS8681 TINA-TI Ref Design

SBAM266.ZIP (135 KB) - TINA-TI Reference Design
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Simulation model

ADS8681 TINA-TI Spice Model

SBAM267.ZIP (40 KB) - TINA-TI Spice Model
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Calculation tool

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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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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 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 (...)
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Reference designs

TIDA-01333 — 8-ch Isolated High Voltage Analog Input Module with ISOW7841 Reference Design

The TIDA-01333 isolated high voltage analog input module reference design has eight channels supporting both, voltage and current measurement. In addition, 4 channels support common-mode voltages up to ±160V. Isolation of +5V line and the Serial Peripheral Interface  (SPI) (...)
Design guide: PDF
Schematic: PDF
Reference designs

TIDA-00764 — 8-ch Isolated High Voltage Analog Input Module Reference Design

This reference design is a high-voltage analog input module with eight channels. Each channel can be used for both voltage and current measurement. The design uses 16-bit analog-to-digital converter (ADC) ADS8681 that can handle input voltage of up to ±12.288 V. This make any (...)
Design guide: PDF
Schematic: PDF
Reference designs

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The circuit represents a high-performance data acquisition (DAQ) solution suitable for processing input signals (up to ±12 V) superimposed on large common-mode offsets (tested up to 155 Vp-p from dc to approximately 15 kHz) relative to the ground potential of the system's main power supply. (...)
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TSSOP (PW) 16 Ultra Librarian
WQFN (RUM) 16 Ultra Librarian
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