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Precision ADCs (<=10MSPS)

ADS8668

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12-Bit 500kSPS 8-Channel SAR ADC With Bipolar Inputs Off 5V Supply

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Data sheet

ADS8668

ACTIVE
Data sheet Order now

Product details

Resolution (Bits) 12 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 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) 73.8 Analog voltage AVDD (Max) (V) 5.25 INL (Max) (+/-LSB) 0.5 Digital supply (Min) (V) 1.65 Digital supply (Max) (V) 5.25
Resolution (Bits) 12 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 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) 73.8 Analog voltage AVDD (Max) (V) 5.25 INL (Max) (+/-LSB) 0.5 Digital supply (Min) (V) 1.65 Digital supply (Max) (V) 5.25
TSSOP (DBT) 38 43 mm² 9.7 x 4.4
  • 12-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: ±0.2 LSB; INL: ±0.2 LSB
    • Low Drift for Gain Error and Offset
    • SNR: 73.8 dB; THD: –95 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)
  • 12-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: ±0.2 LSB; INL: ±0.2 LSB
    • Low Drift for Gain Error and Offset
    • SNR: 73.8 dB; THD: –95 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 ADS8664 and ADS8668 are 4- and 8-channel, integrated data acquisition systems based on a 12-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 ADS8664 and ADS8668 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 ADS8664 and ADS8668 are 4- and 8-channel, integrated data acquisition systems based on a 12-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 ADS8664 and ADS8668 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 ADS866x 12-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with Bipolar Input Ranges datasheet PDF | HTML 14 Jul 2015
Application note Circuit for detecting input floating on ADS8681 ADC PDF | HTML 31 Mar 2021
Application note Reducing Phase Delay by Averaging on ADS8686S with Burst Sequencer Mode PDF | HTML 11 Jan 2021
Circuit design Input protection for high-voltage ADC circuit with TVS diode 26 Jun 2019
Circuit design 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
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

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

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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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 (...)
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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 (...)
User guide: PDF
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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 (...)
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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 (...)
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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 (...)
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 (...)
Schematic: PDF
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TSSOP (DBT) 38 View options

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