LM21215: Bode Plot -- Gain Margin and Phase Margin

Hello Laurie,

Gain Margin: Gain margin is the gain value when the phase passes through 0 degrees. This is measured in decibels and should be a negative number. 

Phase Margin: Phase margin is the value of the phase measured in degrees when the gain passes through zero. This is measured in degrees and should be a positive number.

Stability Conditions:

Sufficient phase margin is required to prevent oscillations. A phase margin of 45 degrees or greater is the design goal. A gain margin of –6 dB is the minimum, while –10 dB is considered good.

Please refer the APP note (Switch-mode power converter compensatin made easy) to understand more about stability and compensation.

Please refer the APP note (How to Measure the Loop Transfer Function of Power Supplies (Rev. A)) to understand how to measure loop transfer function.

Thank you,

Regards,

Moheddin.

Hello Given,

If you don't have any further questions, please close the threat by clicking on Resolved.

Thank you,

Regards,

Moheddin.