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

8 Summary

The slew rate parameter in the data sheet is typically the quickest possible output rate change in V/µs. For low-power op amps, the units can be V/ms. Slew rate is reduced in applications with small inputs and high gains. Input difference voltage, VID, is needed to achieve an output slew rate. Achieving a faster SR requires a larger VID. However, a larger VID makes the virtual ground op amp concept less true, leading to a possible increase in signal distortion. Selecting an op amp with much higher slew rate and bandwidth than needed, to achieve lower signal distortion, is the best option.