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LP2951 minimum ESR

Louis Diana
Intellectual 2180 points

In the data sheet it says:

Features section in front says >12 mohm
Next to last line on Page 15 says 20-30 mohm
Last line on Page 15, says to see Typical Chracteristics for specific ESR requirements - cannot find anything
What is the min ESR?
Also, on Page 15 it says that output capacitor should have a resonant frequency "less than" 500 kHz.  Is this correct?
  • 0
    TI__Expert 8890 points

    No accounting for the data sheet.  The minimum esr is determined by the minimum phase margin for stability.  But the minimum phase margin is determined arbitrarily to be between 30 - 45degrees in accord with how conservative is the engineer writing the data sheet.  It would be best to use the higher minimum esr values in your design - to account for temperature variables.   Regarding the "resonant frequency", the data sheet should read "greater than" 500kHz - you do not want the resonant frequency of the capacitor anywhere near to the control loop bandwidth of the regulator.