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LM5165-Q1: COT operation mode - ESR requirement

Part Number: LM5165-Q1
Other Parts Discussed in Thread: LM5165, LM5156


  • I am willing to design a buck converter based on LM5165 with the next specifications(the calculation file is attached):



  • Based on LM5156 calculation file and datasheet I made the next implementation:



Form the datasheet and app notes (snvu474 ,snvu511) it seems that COT operation mode requires a minimum ESR, which in most of the cases is added externally (like in my schematic R2584, R2585) and based on this fact I have the next questions:


  1. The min ESR value shall be calculated at Input Voltage – Nom or Input Voltage – Min ?
  2. If an external capacitor with low ESR (by ex 100uF ESR<0.5ohm) Is connected to 13V5 output, will the converter work properly due to overall ESR reduction?
  3. What happens if the ESR condition is not met; the converter will not work properly?(poor stabilization, oscillation…)
  4. In order to reduce the output ripple and therefore external ESR a feedforward capacitor(mentioned on datasheet) may be added in parallel with upper feedback resistor – C2586. Is there any relationship for dimensioning this capacitor?

Thank you!