SBOSAI7B November   2023  – July 2024 OPA2891 , OPA891

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information - OPA891
    5. 5.5 Thermal Information - OPA2891
    6. 5.6 Electrical Characteristics - RL = 150Ω
    7. 5.7 Electrical Characteristics - RL = 1kΩ
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagrams
    3. 6.3 Feature Description
      1. 6.3.1 Offset Nulling
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Driving a Capacitive Load
      2. 7.1.2 Low-Pass Filter Configurations
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Selection of Multiplexer
        2. 7.2.2.2 Signal Source
        3. 7.2.2.3 Driving Amplifier
        4. 7.2.2.4 Driving Amplifier Bandwidth Restriction
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 General PowerPAD™ Integrated Circuit Package Design Considerations
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • D|8
  • DGN|8
Thermal pad, mechanical data (Package|Pins)

7.2 Typical Application

This section demonstrates multiplexing several analog input signals to a high-performance driver amplifier that subsequently drives a single, high-resolution, high-speed successive-approximation-register (SAR) analog-to-digital converter (ADC). This example uses the ADS8411 and the TS5A3159 or TS5A3359 as the ADC and the multiplexer, respectively. This application uses the OPAx891 as the operational amplifier.

Figure 7-4 details how the example system consists of an ADC (ADS8411), a driving operational amplifier (OPA891), a multiplexer (TS5A3159), an ac source, a dc source, and two driving operational amplifiers.

The driving amplifiers OPA1 and OPA2 are shown as two OPA891 amplifiers. Alternatively, use a single OPA2891 to save on cost and board space. The purpose of these op-amps is to make the input sources present a low impedance to rest of the circuit. Additionally, to maintain signal fidelity, these operational amplifiers must have low noise and distortion. The third OPA891, labeled OPA3 in Figure 7-4, is used to maintain switching speed and drive the ADC. The passive band-pass filter before the ADC reduces unwanted noise.

OPA891 OPA2891 Multiplexing Set-Up to Drive a High-Performance ADC Figure 7-4 Multiplexing Set-Up to Drive a High-Performance ADC