LM5069: TI FET recommendation

Shinya Sawamoto

Expert 5285 points

Part Number: LM5069
Other Parts Discussed in Thread: CSD19536KTT, CSD18537NQ5A

Hello team,

Do you have a recommendation of TI FET used with LM5069?

Thanks in advance.
S.Sawamoto

over 5 years ago

0 Rakesh over 5 years ago

TI__Guru** 105361 points

Hi Sawamoto,

We recommend to use FETs having strong SOA support such as PSMN4R8-100BSE or CSD19536KTT. Can you share filled up design sheet for review.

https://e2e.ti.com/blogs_/b/powerhouse/archive/2018/04/06/how-to-select-a-mosfet-hot-swap

Best Regards, Rakesh

0 Shinya Sawamoto over 5 years ago in reply to Rakesh

TI__Expert 5285 points

Hi Rakesh,

I'd like to ask an additional question.
The EVM uses different FETs for back to back. Is there any specific reason of choosing different FETs or is it okay for same FETs?

Regards,
S.Sawamoto

0 Rakesh over 5 years ago in reply to Shinya Sawamoto

TI__Guru** 105361 points

Hi Sawamoto,

Q1 is hot-swap MOSFET which needs to have strong SOA support to withstand power stress during fault events and Q2 is OR-ing FET.

The OR-ing FET selection is based on Ron (to meet steady state power loss), voltage rating to support maximum reverse voltage.

Best Regards, Rakesh

0 Shinya Sawamoto over 5 years ago in reply to Rakesh

TI__Expert 5285 points

Thanks a lot, Rakesh.

Allow me to ask one more question.
I understood that Q1 is required stronger SOA than Q2 for fault events.
It looks Q1(SUM50N06-16L) and Q2(CSD18537NQ5A) on the EVM have similar SOA performance.
Is there any specific reason or background why those two devices are selected separately?

Regards,
S.Sawamoto

0 Rakesh over 5 years ago in reply to Shinya Sawamoto

TI__Guru** 105361 points

Hi Sawamoto,

I believe the design might have not optimized much in terms of FET cost. There should not be any specific reason in having stronger SOA FET for ORing side.

Best Regards, Rakesh

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LM5069: TI FET recommendation