LM5180: How to measure phase margin

miyata.fumiki

Part Number: LM5180

When measuring the phase margin, should I put Ri (injection resistor) in front of the FB resistor as shown in the figure below and measure it with FRA?

over 2 years ago

0 Richard Fu22 over 2 years ago

TI__Mastermind 27560 points

Hi,

Since LM5180 supports PSR flyback operation, you cannot use the standard injection resistor method. Instead, you will need to run a load transient step and correlate the appropriate phase and gain margin with the resulting voltage waveform. You may use this app note: www.ti.com/.../slva381b.pdf

Regards,

Richard

0 miyata.fumiki over 2 years ago in reply to Richard Fu22

Prodigy 100 points

Dear Richard san

Thank you for your strong support !

I understood.

Regards,

Miyata

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LM5180: How to measure phase margin