Hi team，
My customer use LM5116MHX in their project. Vin:48V, Vout: 12V, Iomax: 15A. The external MOS is selected as FDMS86540.
When the device operates at 25℃ with three loads of 60W(12V,5A), the test found excessive heat on the chip and the external MOSFET.
Using an infrared thermometer, the following figure shows that the dark blue diamond is a MOSFET, which is 101.2 degrees, and the light blue square is LM5116, which is also 83.9 degrees.
This is the test result that customers have already conducted some heat transfer via heat-conductive silicone blocks on the bottom of the PCBA to the chassis enclosure,
Otherwise, the temperature will increase by about 10 degrees, close to the limit temperature margin of the MOSFET, so it cannot pass the 55 degree high temperature test.
Below is the schematic and MOSFET datasheet.
Could you please help check if there is a problem with the circuit design, or do you have some suggestions to improve the issue?
Schematic
MOSFET datasheet
Thank you.
Regards,
Ivy
