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DCDC phase margin 45 degree

GARAM AN
Intellectual 2010 points

Hello,

Generally, it's informed that under the 45 degree phase margin at 0db is unstable, because of oscillation.

Customer usually ask about this whether my recommendation device phase margin is over than 45 or not at 0db gain margin.

However, I have seen that some customer uses the buck device which is under 45 degree phase margin device.

why they are using the under 45 degree unstable device?

Are there any benefits if they use under 45 degree phase margin unstable device?

  • 0
    TI__Expert 7500 points

    Hi, 

    Actually, as long as the phase margin is above 0 degree at 0db, the system is stable theoretically. But in order to maintain a certain stability margin in real system, 40-45 degree phase margin is desired. With higher phase margin, the system will be more stable but the response time will be longer.

    Thanks,

    Lishuang