LMR51635: Request for Documentation (Shizuoka) LMR51635

Hello Nirasawa,

Thank you for the query!

I will get back to you by today EOD IST.

Regards,

Sourish

Hello Nirasawa,

Here are the answers for your questions]

1) We do not have any such document specifically for the LMR51635. But we do have such a characterization in datasheet of LM43603 as shown below:

Here is one more document where the same plot is provided: Thermal Design made SIMPLE with LM43603 and LM46002

The trend will be similar in the LMR51635 device too.

Here is another document explaining the thermal design: AN-2020 Thermal Design By Insight, Not Hindsight (Rev. C)

You can use other publicly available tools on the internet for helping you in PCB design.

One such example is: Simplify PCB Design with Our Trace Width Calculator | AdvancedPCB

2) The different variant of LMR51635 series would have same thermal resistance equal to the value provided in datasheet.

Regards,

Sourish

Dear Sourish,

Thank you for your reply.
I have one additional question.

Could you please advise under what conditions the thermal resistance values in the LM51635 datasheet are specified? In particular, could you please provide the following information?

• Copper area
• Thermal pad / heat spreader area
• Number of vias

I would greatly appreciate your assistance.

Best regards,
Nirasawa

Hello Nirasawa,

I need to check with the engineer who designed the EVM for the information you asked.

I will get back to you once he replies.

Regards,

Sourish

Dear Sourish,

Thank you for your response.

Regarding the thermal resistance RθJC(top) listed in the datasheet for LM51635, could you please let us know the conditions under which this value was measured?

In particular, we would appreciate your clarification on the following points:

• Copper foil area
• Heat dissipation pattern area
• Number of vias

We would be grateful if you could provide this information.

Best regards,

Nirasawa