TPS54040: Loop Measurements and Slope Compensation

Ryan.Bishop

Expert 3900 points

Part Number: TPS54040

Hello,

One of our customers needs the following information. Thank you!

What is the value of the internal slope compensation?
What is the value of the current sense gain?
Is there a recommended method for loop measurements for an inverting buck configuration?
1. The customer is injecting on TP7/TP8 on the eval board and measuring with respect to “ground”, which is now the -12V output. What they're finding is that they get only noisy gain and phase measurements at low frequencies, with the noise level converging on a signal around 100Hz

Let me know if you have any questions.

Regards,
Ryan B.

over 7 years ago

0 Arief Hernadi over 7 years ago

TI__Mastermind 23845 points

Hi Ryan,

What was the result looks like?

Did they do it as the attached picture?

LoopMeasurement_Negative.pdf

0 Ryan.Bishop over 7 years ago in reply to Arief Hernadi

TI__Expert 3900 points

Hi Arief,

Yes their measurement setup is the same as your attached drawing. I will ask them to post a screenshot of their results so you can see the issue.

In the meantime, do you have any values for questions 1&2?

Regards,
Ryan B.

0 Ryan.Bishop over 7 years ago in reply to Arief Hernadi

TI__Expert 3900 points

Hi Arief,

Here is the plot they are getting using a Ridley AP300, using the same test setup as you've shown.

Let me know if there's any suggestions to get better results for inverting buck loop measurements. Thank you!

0 Ryan.Bishop over 7 years ago in reply to Arief Hernadi

TI__Expert 3900 points

Hi Arief,

Any updates on questions 1&2? Or recommendations on the loop measurements?

Thank you!
Ryan B.

0 Arief Hernadi over 7 years ago in reply to Ryan.Bishop

TI__Mastermind 23845 points

Ryan,

Let's discuss this internally on the email instead of e2e forum. I will closed the thread since the E2E has a timer

Thanks
-Arief

Power management

Power management forum

TPS54040: Loop Measurements and Slope Compensation