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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 mm × 6.4 mm) WQFN (RUM) 16 16 mm² (4 mm × 4 mm)
  • 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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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

Technical documentation

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Top documentation Type Title Format options Date
* Data sheet ADS868x 16-Bit, High-Speed, Single-Supply, SAR ADC Data Acquisition System With Programmable, Bipolar Input Ranges datasheet (Rev. E) PDF | HTML Aug 15, 2022
Application brief Precision ADCs in Servo Drives (Rev. A) PDF | HTML Oct 29, 2025
Circuit design Input Protection for High-Voltage ADC Circuit with TVS Diode (Rev. A) PDF | HTML May 2, 2023
Product overview Bridge Sensor Solution (Rev. A) PDF | HTML Jan 27, 2023
Product overview PLC Analog Input Front-End Architectures PDF | HTML Jul 31, 2022
Application note Cost-Optimized, High-Performance Front-End Design for Analog Input Modules PDF | HTML Jun 22, 2022
Application note EMC Compliance Testing for Precision ADC Systems (Rev. A) PDF | HTML May 27, 2022
Application note Circuit for detecting input floating on ADS8681 ADC PDF | HTML Mar 31, 2021
Circuit design Circuit for protecting ADC with TVS diode and PTC fuse PDF | HTML Aug 3, 2020
Application note Extending Input Voltage Range and Understanding Associated Errors for ADC With I Nov 9, 2018
White paper Fully integrated signal and power isolation – applications and benefits Feb 10, 2017
White paper Enabling Faster, Smarter, and More Robust Solutions for SAR ADSx With multiSPI Nov 8, 2016
More literature ADS8681EVM-PDK Quick Start Guide Aug 4, 2016
White paper Voltage-reference impact on total harmonic distortion Aug 1, 2016

Design & development

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

Evaluation board

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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 (...)

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GUI for evaluation module (EVM)

SBAC146 — ADS8681EVM-PDK GUI

Evaluate the ADS8681 and ADS8681W using the evaluation module (EVM) product development kit (PDK)
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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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ANALOG-ENGINEER-CALC — PC software analog engineer's calculator

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Design tool

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TIDA-00106 — 16-Bit 1-MSPS Data Acquisition Reference Design, Isolated for High-Voltage Common-Mode Rejection

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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Reference design

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 (...)
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TSSOP (PW) 16 Ultra Librarian
WQFN (RUM) 16 Ultra Librarian
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