LM5069: LM5069 Mosfet Selection and Reverse Polarity.

Hi, 

Welcome to e2e! Look below for my comments/feedback in red: 

1) What happens to the IC and what is its reaction during reverse polarity?

You're in luck! We have collateral on having back-to-back FET's for reverse polarity protection using the LM5069. Here's an app note discussing reverse polarity protection: http://www.ti.com/lit/an/snva683/snva683.pdf.

We also created an EVM board with waveforms and test results using this type of circuit topology. The user's guide can be found here: http://www.ti.com/lit/ug/slvuaa1/slvuaa1.pdf. 

The product folder to order this EVM board can be found here: http://www.ti.com/tool/lm5069evm-627. 

2) On the MOSFET, since the maximum current is 9A, and the maximum input voltage is 48V is it safe to use mosfet BUK9Y58-75B with Vds 75V, Id 20.7A & 60.4 watt power?

The best way to find out if a particular design will work with any FET chosen is to use our nifty calculator tool for the LM5069. Using our design calculator tool with this device will help review and troubleshoot your design, and would greatly speed up the back-forth communication of questions we would have for information needed for any future review (such as total output cap including anything connected downstream from the output node, which may not be shown on a partial schematic).

You can find it by going to www.ti.com/hotswap ==> click on “Tools & software” ==> then click on “Hot Swap design calculator tools”

For help on filling out the excel spreadsheet, we have video tutorials. They explain how to enter the correct values cell by cell. Please watch these videos at www.ti.com/hotswap ==> Click on “Support & Training” tab.

I hope this helps :-)

Best Regards, 

Aramis P. Alvarez