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

1 Introduction

A feature that is becoming more common in modern operational amplifiers (op amps) is the ability to enable and disable the device. Texas Instruments (TI) currently has over 60 op amps with shutdown functionality and more on the way. This application note will provide an explanation of various shutdown parameters and design considerations for the TLV90xxS family of devices including the TLV900xS, TLV905xS and TLV906xS.

Amplifiers with shutdown functionality are well suited to applications that are battery powered and require portions of their system to turn off to save power. Examples of such systems include smoke detectors, PIR sensors, field transmitters and remote sensors. "Low power" amplifiers that do not have shutdown functionality typically have some tradeoffs, such as exchanging low quiescent current for very low bandwidth. On the other hand, amplifiers with shutdown functionality can offer low current consumption when not in use and greater bandwidth when in use. Despite requiring a bit more control, they can mitigate this power for performance tradeoff.

Amplifiers with shutdown functionality allow the user to "enable" and "disable," or "shutdown," the device even while the supply rails remain powered. When the amplifier is enabled, it functions as expected by amplifying the difference between the inverting and non-inverting inputs by the open loop gain (AOL) and consuming the full amount of quiescent current (IQ). When the amplifier is in shutdown, it consumes much less quiescent current and the output becomes high impedance.

Devices that are in a single or dual channel package usually have one SHDN pin per amplifier. Quad package devices typically come with two SHDN pins: one for controlling channels 1 and 2 and another for controlling channels 3 and 4. Figure 1-1 and Figure 1-2 show example pinouts for a dual channel shutdown device (TLV9062S) and a quad channel shutdown device (TLV9064S).

Figure 1-1 TLV9062S DGS Package
Figure 1-2 TLV9064S RTE Package