LM5141-Q1: How to measure loop gain and phase on EVM when FB is not used

RYO

Intellectual 2000 points

Part Number: LM5141-Q1

Hello all,

Thank you for your support always. I have a question about LM5141-Q1 EVM.

How can I measure the loop gain and phase on EVM? The FB pin is shorted to AGND so that the output of the device is 5V. I'm thinking replacing R9 with 50-ohm resistor and connect FRA cables at the ends of the resistor like below but I'm not sure.

Or should I solder resistors on the feedback trace?

Best regards,
RYO

over 7 years ago

0 David Baba over 7 years ago

TI__Mastermind 40040 points

Hello RYO,

Unfortunately you cannot measure loop gain without using external resistors. Will need to install external resistors and place 50 ohm in series with Top FB resistor.

David.

0 RYO over 7 years ago in reply to David Baba

TI__Intellectual 2000 points

Hello David,
Thank you. I understood. I'll put a FB resistors so that the IC sets the output voltage following those resistor network.
Best regards,
RYO

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LM5141-Q1: How to measure loop gain and phase on EVM when FB is not used