Hi,

When Iout = 20 A, Phase + 180 deg is enough in all frequency.

When Iout = a few A,

Iout = Aの場合、PM > 70 deg

However, Phase + 180 deg < 20 deg @ 2.5 kHz.

Is it stable when Iout = a few A ? ## Top Replies

• If at crossover frequency, PM>45 deg, the loop is stable.

Parents
• We usually check the phase margin at crossover frequency, for your design, at crossover frequency, the phase margin is larger than 70 degree, then the loop is stable.

• We usually check the phase margin at crossover frequency, for your design, at crossover frequency, the phase margin is larger than 70 degree, then the loop is stable.

Children
• You mean it is not necessary to consider about phase @ lower frequency than crossover frequency ?

If so, is it general theory ?

Please tell me why that feedback loop is stable.

• Can you post the loop gain and phase together?

• I posted the loop gain and phase.

Vin=5 V , Vout = 0.85 V, Iout =5 A

Crossover frequency : fc = 45 kHz.

Even in the case of existing the frequency region that the phase < 45 deg (@ f < fc),

Is the feedback loop stable if PM > 45 deg ? • If at crossover frequency, PM>45 deg, the loop is stable.