SBOA367B December   2019  – June 2022 TLV9001 , TLV9002 , TLV9004 , TLV9051 , TLV9052 , TLV9054 , TLV9061 , TLV9062 , TLV9064

 

  1.   Designing for TLV90xxS operational amplifiers with shutdown
  2.   Trademarks
  3. 1 Introduction
  4. 2 Shutdown Specifications
  5. 3  SHDN Pin Limits and Connections
  6. 4 Output Behavior During Enable and Shutdown
  7. 5 Enable Time and Shutdown Time Factors
    1. 5.1 Quiescent Current
    2. 5.2 Temperature
    3. 5.3 Load
    4. 5.4 Feedback Path
  8. 6 Impact on Commonly Used Circuit Configurations
    1. 6.1 Inverting Amplifier Circuit
    2.     14
    3. 6.2 Non-Inverting Amplifier Circuit
    4.     16
    5. 6.3 Buffer Circuit
    6.     18
  9. 7 Advanced Circuit Functionality Using Amplifiers With Shutdown
  10. 8 Conclusion
  11. 9 References
  12. 10Revision History

6 Impact on Commonly Used Circuit Configurations

Designers must take into account the effects of a disabled TLV90xxS device on their circuit, such as the input signal unexpectedly appearing at the output node due to the amplifier's parasitic input capacitance. This section will discuss how to model circuits with a disabled amplifier. It will also demonstrate the effects of a disabled amplifier on the performance for a few, common configurations.

To model a disabled amplifier in a circuit, one should:

  1. Replace the inputs of the op amp with high impedance nodes.
  2. Model the common mode and differential input capacitance of the amplifier with parasitic capacitors. Use the capacitances CCM and CID provided in the data sheet for these components.
  3. Model the output pin of the op amp as a resistor and a capacitor in parallel. Match their values to the ZSHDN specification provided in the data sheet.