SLOA332A July   2023  – September 2024 LMV821-N , LMV831 , OPA2991 , OPA345 , OPA376 , OPA376-Q1 , OPA377 , OPA377-Q1 , OPA4991 , OPA991 , TL074 , TLV376 , TLV9001 , TLV9002 , TS321

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Slew Rate Definition
    1. 1.1 Virtual Ground and Slew Rate
  5. 2 Bipolar Op Amp Slew Rate Example
  6. 3 CMOS Op Amp Slew Rate Example
    1. 3.1 Slew Boost Example 1
    2. 3.2 Slew Boost Example 2
    3. 3.3 Slew Boost Summary
  7. 4 Four Methods to Determine Boost or No Boost Using the Data Sheet
    1. 4.1 Method 1: Compare Slew Rate Versus Gain Bandwidth
    2. 4.2 Method 2: Compare Quiescent Current Versus Similar SR Devices
    3. 4.3 Method 3: Evaluate Large Signal Response
    4. 4.4 Method 4: Evaluate Small Signal Response
  8. 5 Slew Rate Dependencies on Circuit Signal Levels and Op Amp Gain Set by Feedback Network
  9. 6 How Much Output Slew Rate is Needed to Support a Sine Wave or Other Non-step Inputs
  10. 7 Stability Also Plays a Role in Observed Slew Rate
  11. 8 Summary
  12. 9 References
  13. 10Revision History

7 Stability Also Plays a Role in Observed Slew Rate

Very stable circuits with 90 degrees or more phase margins have longer rise times with slower observed SR because feedback is fully negative. The advantage of very stable circuits is the lack of overshoot. Critically stable and poor stability circuits with 45 degrees or less phase margin have a significant positive feedback effect that shortens edge times and increases observed SR at the expense of having overshoot, ringing, or possible oscillation.