LM5145-Q1: Request for Review – LM5145-Q1 Schematic

Ajnas C

Part Number: LM5145-Q1

Tool/software:

Hi Team,

Could you please support me by reviewing the attached LM5145-Q1 schematic at your earliest convenience? I would appreciate your recommendations on any improvements that could enhance the performance or reliability of the design.

Thank you for your support.

Regards,

Ajnas C

1 month ago

0 Tony Koulong 1 month ago

TI__Prodigy 460 points

Hi Ajnas,
Your schematic looks okay.

0 Timothy Hegarty 1 month ago

TI__Guru 73682 points

Hi Ajnas,

The low-side FET is too low Rdson and thus very capacitive. It's Qg, Qoss and especially Qrr are huge. Go with higher Rdson for 8A. Consider using Fsw = 300kHz to optimize efficiency vs. size tradeoff.

There is a 20k internal pulldown on SYNCIN, so pulling it up with a 20k will put VCC/2 at the pin. Also, you may want to add input filter damping. Send on the complete quickstart file so I can review component losses, compensation, etc.

Regards,

Tim

0 Ajnas C 1 month ago in reply to Timothy Hegarty

Prodigy 10 points

Hi Tim,

Thanks for the replay, can i use the High side FET for LOW side also? Could you please suggest the SYNCIN pullup value?

Additionally please provide any reference or suggestion for the input filter damping circuit?

LM5145_quickstart_calculator_A5.xlsm

Please suggest if any modifications needed, if any additional details needed please let me know. Looking for your response.

Regards,

Ajnas

0 Ajnas C 1 month ago in reply to Ajnas C

Prodigy 10 points

Dear Team,

I have modified the schematics based on your feedback with Fsw=300khz. Please review and share the comments.

Additionally, attached quickstart-calculator - LM5145_quickstart_calculator_A5.xlsm. Please provide the feedback at your earliest.

Regards,

Ajnas C

0 Tony Koulong 1 month ago in reply to Ajnas C

TI__Prodigy 460 points

Hi Ajnas,

I don't see a filter on your inputs. As Tim, said I would also advise you to add damping filter in your input. If you don't care about EMI, you can pass it. Here is an EVM testing that was done. Hopefully this can help you. Also, I'm unable to download your quick start calculator. I don't if you can upload it a different way. snvu545a.pdf

0 Ajnas C 1 month ago in reply to Tony Koulong

Prodigy 10 points

Dear Tony,

Added the damping filter, please review the same.

Please check the quick start calculator below link,

https://docs.google.com/spreadsheets/d/1OrCOaRJciEB88MOtHW-ugSJ3xZ8TIs7Z/edit?usp=sharing&ouid=106053338225852318063&rtpof=true&sd=true

Regards,

Ajnas C

+1 Tony Koulong 1 month ago in reply to Ajnas C

TI__Prodigy 460 points

Hi Ajnas,
Here is my calculator, I tried to followed the calculator you uploaded. I still wasn't able to download it, but i could see what you were doing. 1212.LM5145_quickstart_calculator_A5.xlsm

Your schematic looks good but i think you need to adjust the position of your inductor like the one below