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IBS
May 19th, 2017, 02:27 AM
Hello,

Does anybody has worked with IFX91041EJV50 with success?
We would use it in our application for a approximated current of 1A at 5VDC output (Input is 24VDC).
Test layout which follow the spec of part was made, but at output current of 700mA the IC goes very hot ~55degr.
Also I searched for more information's about efficency or curve with temp., but couldn't find it on INFINEON.

Could anybody help in this matter?
Or it is normal that IC get such temperatures?

Kind regards
Kersten

berbra
May 22nd, 2017, 06:49 AM
Regrettably, there are no efficiency curves as requested available in the documentation.
For the test layout you mean the IFX91041 Application Information (https://www.infineon.com/dgdl/091130AppNote_IFX91041_Filter_Rev1.0.pdf?fileId=db 3a30432a14dd54012a3d1cc78b59e6) and the datasheet has been used as the source for your application.
You will have to take care about the specs for the passive components, the low ESR for the capacitor and take care not to drive the inductance into saturation and last you will have to use a schottky diode.
It is important that the inductor maintains its inductance at the elevated operating temperature based on board temperature and inductor losses. A saturating inductor will lead to excessive current in the MOSFETs, impact application reliability or even lead to sudden destruction due to electrical overstress of the internal MOSFET. You will have to solder the part's exposed pad to a heatsink area and GND by low inductance wiring.

Check with an oscilloscope the signals: You should try to check whether your inductance is going to saturation and try to find out what are the power losses of the output MOSFET. The aim is to find with the help of the therrmal resistances (data sheet) the temperature delta of the package.