TPS544B20EVM-634: Bode Plots Measurement

Joe Chen40

Prodigy 95 points

Part Number: TPS544B20EVM-634

Hi e2e,

Recently, a customer had an inquiry about measuring bode plots at both DIFFO pin and Vout+.

He was wondering if there is any difference between these 2 pins when measuring the bode plots?

Questions:

1. Is there any difference between these 2 points? I noticed for DIFFO pin, the signal communicates within IC and for Vout+, the signal go through external parts.

2. If different, which point should I measure in order to obtain the most accurate result?

Thanks,

Joe

over 5 years ago

0 Mathew Jacob1 over 5 years ago

TI__Expert 5900 points

Joe,

I would recommend using the Vout+ sense resistor for the bode plot measurements.

Regards,

Mathew

0 Joe Chen40 over 5 years ago in reply to Mathew Jacob1

Prodigy 95 points

Hi Mathew,

Thank you for your reply. May I ask what is the reason for using Vout+ pin?

Best,

Joe

0 Mathew Jacob1 over 5 years ago in reply to Joe Chen40

TI__Expert 5900 points

Joe,

Because it includes the gain and response of the DIFF amp also and is inclusive of the entire loop. In my measurements I have got better correlation with simulations and lab measurements with this method.

Regards,
Mathew

0 Joe Chen40 over 5 years ago in reply to Mathew Jacob1

Prodigy 95 points

Mathew,

Thank you very much for your help. This is absolutely helpful.

Best,
Joe

0 Mathew Jacob1 over 5 years ago in reply to Joe Chen40

TI__Expert 5900 points

Great

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TPS544B20EVM-634: Bode Plots Measurement