LM5116: damage half bridge MOSFETs

Gary Zeng

Part Number: LM5116

Tool/software:

Hi Ti Experts,

My customer is using LM5116 for the power supply of Laser diode.

There are only two times that two MOSFETs behind the LM5116 are demaged.

Could you please help review the schematic:

0 EricLee 9 months ago

Hello Gary

I cannot find any obvious mistake on the schematic. Please share the MOSFET and the inductor datasheets for more investigation.

Please check which pin is damaged between drain-source, gate-source. It is also possible the MOSFET is thermally damaged.

If possible, please share the picture of the damaged board.

-EL

0 Gary Zeng 9 months ago in reply to EricLee

Hi Eric,

Thanks for your reply.

MOSFET's PN is NCEP078N10AK.

Damaged MOSs are lost. But What we can confirm that there is no obvious damage on IC's package.

As for inductor, please see below datasheet.

0 EricLee 9 months ago in reply to Gary Zeng

Hello Gary

8.2uH is not in the attached PDF file, but looks like the saturation current of 8.2uH is ~2.2A, which might be too small.

Please measure the inductor current using a current probe and check if any saturation at hottest ambient temperature.

-EL

0 Gary Zeng 9 months ago in reply to EricLee

Hi Eric,

PN is HVC1265-8R2M. You can find it in front datasheet.

0 EricLee 9 months ago in reply to Gary Zeng

Hello Gary

If you are sure the inductor current saturation level is high enough, please measure V(HO-SW) and V(LO-GND) accurately using two differential probes.

Dead-time might be not enough.

-EL

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