LM65645-Q1: Functional Safety FIT Rate, FMD and Pin FMA Document

Thank you for the link, is there any mechanism present in the device to prevent passing 48V through to the output in the event of a shorted FET?  I see the FIT rate for that particular failure mode is 5%, however I'm looking for some additional data to justify removing an unnecessary (in my opinion) safety switch.

Hi Stephen,

I think you need a safety switch like an efuse to protect against FET short failure. There must be an element to break the short path.  

We are also developing an Functional Safety device LM68645-Q1, which is in preview at ti.com (https://www.ti.com/product/LM68645-Q1), and it will be released very soon.  You may consider it, but a safety switch will still be needed to protect against buck converter MOSFET short.  Note that the LM68645 integrates the control for the external efuse, which may simplify your design with efuse.

Hope this clarifies. 

Best Regards,

Youhao

Hi Youhao,

Thanks for the clarification, we'll have to see what the functional safety requirements are and if any safety goals relate to this particular failure mode.

Best regards, 

Steve

Hi Stephen,

Understood. Please find out what you really want to achieve, then we can discuss on how to prevent an overdesign. 

Best Regards,

Youhao