LM5156: Variable VOUT and Compensation

Evan Cornell

Part Number: LM5156

I'd like to use LM5156 with trim-pot in feedback loop to generate VOUT=20-35V at IOUT_max=4A from VIN=8-16V. How should compensation and current sense components be selected to achieve this without converter instability?

Obviously the FET and diode need to be sized for the highest voltage operating point.

Thanks!

over 4 years ago

0 Stefan Schauer over 4 years ago

TI__Guru 69161 points

Hi Evan,

thanks for using the E2E forum.

You are right the FET and Diode needs to be sized for the highest voltage operating point and also for the highest current (@ lowest VIN).

For the loop stability: you also need to consider the different operating points. You can use the Quickstart Calculator for that

LM5156 data sheet, product information and support | TI.com

Best regards,

Stefan

0 Evan Cornell over 4 years ago in reply to Stefan Schauer

Expert 1540 points

Stefan,

Is there a rule of thumb, like, use compensation components that are calculated from lowest VIN and highest VOUT?

Thanks,
Evan

+1 Stefan Schauer over 4 years ago in reply to Evan Cornell

TI__Guru 69161 points

Hi Evan,

starting with lowest VIN and highest VOUT with max load is a good approach but i still recommend to at least check different output voltage and load points with the quick start calculator.

Best regards,

Stefan

0 Stefan Schauer over 4 years ago in reply to Stefan Schauer

TI__Guru 69161 points

Hi Evan,

I have not seen an update on this thread for the last 7 days.
If the issue is solved it would be great to press the is solved button.
If there is still something open, just let me know with the new details.
Best regards,

Stefan

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LM5156: Variable VOUT and Compensation