SBOS512E March   2010  – November 2020 OPA2365-Q1 , OPA365-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Operating Characteristics
      2. 7.3.2 Basic Amplifier Configurations
      3. 7.3.3 Input and ESD Protection
      4. 7.3.4 Rail-to-Rail Input
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Capacitive Loads
      2. 8.1.2 Achieving an Output Level of Zero Volts (0 V)
      3. 8.1.3 Active Filtering
      4. 8.1.4 Driving an ADS7822-Q1 Analog-to-Digital Converter
      5. 8.1.5 Driving ADS1115-Q1 Analog-to-Digital Converter
    2. 8.2 Typical Application
      1. 8.2.1 Fast Settling Peak Detector
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Bandpass Filter 1.5 kHz to 160 kHz and 40-db Flat Gain
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.2 Achieving an Output Level of Zero Volts (0 V)

Certain single-supply applications require the operational amplifier output to swing from 0 V to a positive full-scale voltage and have high accuracy. An example is an operational amplifier employed to drive a single-supply ADC having an input range from 0 V to 5 V. Rail-to-rail output amplifiers with very light output loading may achieve an output level within millivolts of 0 V (or +VS at the high end), but not 0 V. Furthermore, the deviation from 0 V only becomes greater as the load current required increases. This increased deviation is a result of limitations of the CMOS output stage.

When a pulldown resistor is connected from the amplifier output to a negative voltage source, the OPA365-Q1 can achieve an output level of 0 V, and even a few millivolts below 0 V. Below this limit, nonlinearity and limiting conditions become evident. Figure 8-2 illustrates a circuit using this technique.

GUID-F2AE143E-3E54-4612-9CDA-DB0110753DB6-low.gif Figure 8-2 Swing-to-Ground

A pulldown current of approximately 500 µA is required when OPA365-Q1 is connected as a unity-gain buffer. A practical termination voltage (VNEG) is −5 V, but other convenient negative voltages also may be used. The pulldown resistor RL is calculated from RL = [(VO −VNEG)/(500 µA)]. Using a minimum output voltage (VO) of 0 V, RL = [0 V−(−5V)]/(500 µA)] = 10 kΩ. Keep in mind that lower termination voltages result in smaller pulldown resistors that load the output during positive output voltage excursions.

This technique does not work with all operational amplifier, and should only be applied to operational amplifiers, such as the OPA365-Q1, that have been specifically designed to operate in this manner. Also, operating the OPA365-Q1 output at 0 V changes the output stage operating conditions, resulting in somewhat lower open-loop gain and bandwidth. Keep these precautions in mind when driving a capacitive load because these conditions can affect circuit transient response and stability.