LM5141-Q1: The external mosfet selection on the webench

Sherry Liang

Part Number: LM5141-Q1
Other Parts Discussed in Thread: LM5141, CSD18563Q5A, LM25141-Q1

Dear team,

When I use the Webench to simulate the LM5141-Q1, the MOSFET they recommend is 60V,50A. Do I need such a high rating mosfet? Do you have such documents to describe how to select the mosfet's rating values?

Thanks & Best Regards,

Sherry

over 6 years ago

0 Timothy Hegarty over 6 years ago

TI__Guru 66522 points

Hi Sherry,

Some of the 5 x 6mm package MOSFETs are rated for 50A, although they are never capable of such a current in practive. However, the thermal performance of the 5 x 6mm package is required if the ambient temperature is high.

If you do not need automotive grade, then consider the CSD18563Q5A 60V NexFET. Note that the Rds(on) must be rated at Vgs = 4.5V as the LM5141 has a 5V gate drive amplitude.

We have recently uploaded a new version of the LM5141-Q1 quickstart file - it's available by download from the product folder. Please use this to assist with component selection and power loss calculations. For example, a 1.5uH inductor is sufficient at a switching frequency of 2.2MHz (assuming a 9mOhm shunt resistor).

Regards,

Tim