12-Bit 8-Channel Bipolar SAR With Software-Selectable Input Ranges


Product details


Resolution (Bits) 12 Number of input channels 8 Sample rate (Max) (kSPS) 1000 Interface type SPI Architecture SAR Input type Single-Ended Multi-channel configuration Multiplexed Rating Catalog Reference mode Ext, Int Input range (Max) (V) 10 Input range (Min) (V) -10 Features Comparator Operating temperature range (C) -40 to 125 Power consumption (Typ) (mW) 14.45 Analog voltage AVDD (Min) (V) 2.7 SNR (dB) 71.8 Analog voltage AVDD (Max) (V) 5.25 INL (Max) (+/-LSB) 1.5 Digital supply (Min) (V) 1.65 Digital supply (Max) (V) 5.25 open-in-new Find other Precision ADCs (<=10MSPS)

Package | Pins | Size

VQFN (RGE) 24 16 mm² 4 x 4 open-in-new Find other Precision ADCs (<=10MSPS)


  • Selectable Input Range:
    ±10V, ±5V, ±2.5V, 0V to 10V, or
    0V to 5V
    Up to ±12V with External Reference
  • No Latent Conversions Up to 1MSPS
  • Outstanding Performance:
    12 Bits No Missing Codes
    INL: ±0.9LSB
    SNR: 71.8dB
  • Highly Integrated:
    4- or 8-Channel Input Mux
    Temperature Sensor
    Internal Voltage Reference
    Alarm Thresholds for Each Channel
  • Low Power:
    14.45mW at 1MSPS
    5.85mW at 0.1MSPS
    Flexible Power-Down Mode
  • SPI™-Compatible Serial Interface
  • Extended Temperature Range:
    –40°C to +125°C
  • Small Footprint: 4mm × 4mm QFN Package
open-in-new Find other Precision ADCs (<=10MSPS)


The ADS8634 and ADS8638 (ADS8634/8) are 12-bit analog-to-digital converters (ADCs) capable of measuring inputs up to ±10V at 1MSPS. Using a successive approximation register (SAR) core, these ADCs provide a sample-and-hold front-end with no latency in conversions. The ADS8634 includes an input multiplexer (mux) for measuring up to four inputs. The ADS8638 can measure up to eight inputs.

In addition to the input multiplexer, the ADS8634/8 feature an internal temperature sensor, voltage reference, and a digital comparator for setting alarm thresholds on each input; therefore, a minimal amount of external components are required. A simple SPI-compatible interface provides for communication and control. The digital supply operates from 5V all the way down to 1.8V for direct connection to a wide range of processors and controllers.

Ideal for demanding industrial measurement applications, the ADS8634/8 are fully specified over the extended industrial temperature range of –40°C to +125°C and are available in a small form-factor QFN-24 package.

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

Technical documentation

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Type Title Date
* Data sheet 12-Bit, 1MSPS, 4-/8-Chan, Bipolar-Input, SAR ADC w/ Software-Selectable Ranges datasheet (Rev. A) Aug. 03, 2011
User guide ADS8638EVM-PDK User Guide (Rev. A) Feb. 02, 2016
E-book Best of Baker's Best: Precision Data Converters -- SAR ADCs May 21, 2015
Application note Determining Minimum Acquisition Times for SAR ADCs, part 2 Mar. 17, 2011

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

ADCPro™ is a modular software system for evaluating analog-to-digital converters (ADCs) without the need for expensive logic analyzers and complex analysis routines. Used alone it is suitable for performing analysis on data sets captured from ADC testing; when paired with a Texas Instruments (...)


ADCPro software from Texas Instruments will simplify the tasks of collecting and analyzing ADC data, and ease evaluation. With it, you can easily set up an evaluation system that may not exactly replicate the manufacturer's system, but still arrive at meaningful results that can be compared to (...)

document-generic User guide

The ADS8638EVM-PDK is designed to evaluate the ADS8614, ADS8618, ADS8634, and ADS8638 analog to digital converters. These 12/16-bit, four or eight channel, SAR converters offer multiple true bipolar and unipolar ranges in addition to a variety of alarm options. An LED is installed on the EVM board (...)

  • Contains all support circuitry needed for the ADS8638 family of parts
  • Serial interface header to easily attach to TI DSP based communication systems
  • Voltage reference options: ADC internal reference, onboard 2.5V reference, or external reference
  • Onboard OPA140 to drive an ADC input channel
  • LED used to (...)

Design tools & simulation

SBAM099A.ZIP (63 KB) - IBIS Model
SBAM188A.ZIP (48 KB) - TINA-TI Spice Model
SBAM189A.TSC (4340 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
  • (...)

Reference designs

12-Bit, 8 Channel, Integrated Analog Input module for Programmable Logic Controllers (PLC)
TIDA-00119 TIDA-00119  is a complete, highly-integrated PLC analog input module front-end reference design that is designed and tested to meet IEC61000-4 standards for industrial automation systems. The design can be configured for 4 differential inputs or 8 single-ended inputs with 12-bit ADC resolution (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

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VQFN (RGE) 24 View options

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