Data Acquisition for MUX and Step Inputs, 18 bits, 1uS Full Scale Response Reference Design


Design files


This verified design is a high performance data acquisition system (DAQ) using an 18-bit SAR ADC, ADS8881 at a throughput of 1MSPS. This design has been optimized to provide 18-bit settling performance for a Full Scale Step Input signal, thus leading to excellent system linearity. Such an input stimulus is more applicable in MUXed applications for transition between channels with different input voltages. The input driver for the ADC uses the OPA350 for high bandwidth (small & large signal), output current drive and linear rail-to-rail input and output operation. The reference buffer drive utilizes a composite buffer made out of THS4281 & OPA333 to get the desired performance at lowest power consumption. This DAQ block achieves a ±2.5LSB INL performance for a total power consumption of less than 70 mW.

  • 18-bit, 1-MSPS sampling rate
  • DC, MUX'ed, and Full Scale Step Inputs
  • Optimization: Transient Settling
  • Power: 70 mW @ AVDD = 5 V
  • Utilizes ADS8881 (18 bit, 1 MSPS SAR ADC), OPA2350 (Input), THS4281 + OPA333 + REF5045 (Reference)
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDR116B.PDF (172 K)

Detailed schematic diagram for design layout and components

SLAC582.ZIP (1882 K)

Detailed schematic diagram for design layout and components

TIDR115B.PDF (103 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDC011A.ZIP (1436 K)

Design file that contains information on physical board layer of design PCB


Includes TI products in the design and potential alternatives.

Precision ADCs

ADS888118-Bit, 1-MSPS, 1-Ch SAR ADC with True-Differential Input, SPI Interface and Daisy-Chain

Data sheet: PDF | HTML
High-speed op amps (GBW ≥ 50 MHz)

THS4281Very Low-Power High Speed Rail-To-Rail Input/Output Voltage Feedback Operational Amplifier

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA2350Dual single-supply, rail-to-rail, high speed, low-noise operational amplifier

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA333Micropower, 1.8-V, 17-µA zero-drift CMOS precision operational amplifier

Data sheet: PDF | HTML
Series voltage references

REF50454.5-V, 3-µVpp/V noise, 3-ppm/°C drift precision series voltage reference

Data sheet: PDF | HTML
Series voltage references

REF60454.5-V, 5-ppm/°C high-precision voltage reference with integrated buffer & enable pin

Data sheet: PDF | HTML

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Technical documentation

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Type Title Date
* User guide 18-Bit Data Acquisition (DAQ) Block Optimized for 1-μs Full-Scale Step Response (Rev. C) Feb. 02, 2017

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