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

4.2 Method 2: Compare Quiescent Current Versus Similar SR Devices

The second method is to compare the quiescent current (IQ) per channel to other op amps that have similar supply voltage maximums and similar slew rates. IQ and GBWP are proportionally related. If IQ is very low or part of a lower bimodal distribution, then slew boost is expected. If IQ is near the median or above the median value, then boost is not expected. TLV9001 has a very low IQ, which makes boost very likely. LMV831 is lower than the median IQ value, but much greater then the lowest IQ, therefore, boost or no boost is inconclusive using this test.

Table 4-2 Device Parameters Used in Method 2 to Determine Presence of Boost
Part NumberIq/CH (mA)GBWP (MHz)SR (V/µs)Boost?
TLV90010.0612Likely
LMV8310.253.32Inconclusive
LMV821-N0.305.62Inconclusive
OPA3770.765.52No
OPA3760.765.52No
TLV3760.825.52No