LM25118: schematic review

Jon Nohl

Part Number: LM25118

Tool/software:

Hi, would someone be able to able to review the schematic of a design for this DC converter? Can I post the schematic here? Is this public or only seen by TI employees?

Thanks,

Jon

3 months ago

0 Stefan Schauer 3 months ago

TI__Guru 58641 points

Hi Jon,

this a public forum and the posts can be seen by everyone.

If you like to send the schematic in a private message - just hover with the mouse over by avatar and select send private message.

In this case please also add a note here to - so that i know a private message has been send.

Please also attach the filled out LM5118QUICK-CAL to this thread? This would be the most efficient workflow for us to do a schematic review.

Best regards,

Stefan

+1 Jon Nohl 3 months ago in reply to Stefan Schauer

Prodigy 10 points

Thank you Stefan. I will be sending you a PM.

0 Stefan Schauer 2 months ago in reply to Jon Nohl

TI__Guru 58641 points

Hi Jon,

values in calculator:

for Rcomp i suggest to go to 7k2 to get some more phase margin.

for Rsense you have selected a higher value then suggested: note: this will decrease your current limit by ~ 9% - still OK as you have 20% margin but something to consider

Scheamtic:

Most values in calcualtor and Schematic do not match!

10uF input and 10uF output cap looks very low

Layout:

cs / CSG connection to sense resistor should be done as a Kelvin connection - not sharing the GND line

LO line is quite thin - Same for HS and HO - note this are the drive lines for the Gate signals of the MOSFET and have high dynamic

Note: area build be HO / HS should be as small as possible and can be optimized .

Best regards,

Stefan

0 Jon Nohl 2 months ago in reply to Stefan Schauer

Prodigy 10 points

Thanks for your reply Stefan! We will review your suggestions.

0 Jon Nohl 2 months ago

Prodigy 10 points

Hi Stefan,

Attached is a webench design that I generated based on our needs. The webench design selected a Rcomp resistor size of 15k4. In your post you recommended a resistor size of 7k2. Can you tell me why the difference?

Thank you!