TPS61178: Phase margin during PFM operation

yasuharu suyama

Part Number: TPS61178

Hi team,

The phase margin waveform during PFM operation is zero cross even in the low frequency range, and it is difficult to judge that it is stable. However, since ringing has not been confirmed in the step response, it is considered that the phase margin is secured.
Please tell me the reason why this phase margin waveform is obtained.

regards,

over 2 years ago

+1 Yichen Xu over 2 years ago

TI__Expert 4760 points

Hi Yasuharu,

May I how what your test condition is and how you test it?

+1 Yichen Xu over 2 years ago in reply to Yichen Xu

TI__Expert 4760 points

Hi Yasuharu,

The system is conditionally stable, the detail is discussed here:

www.venableinstruments.com/.../why-stable-systems-do-not-oscillate

0 yasuharu suyama over 2 years ago in reply to Yichen Xu

Prodigy 10 points

Hi Yichen,

Thanks for the interesting report!
It seems dangerous to judge the stability from the result of the step response, and it seems that the gain needs to be adjusted. Let's change the constant.

Best Regards,

Y.suyama

Power management

Power management forum

TPS61178: Phase margin during PFM operation