TPS54336A: Power supply chip's lower MOSFET burned out

Hi WJZ

Please let me check and get back to you later.

Thanks and best regards.

Thank you. Did you notice any abnormalities? Or do you have any analysis direction regarding the burnt MOSFETs under the power supply chip?

Hi Wjz

The waveform looks normal.  Can you please share the layout image? And what's the DPPM? Do we know under what operate condition will the damage happen?

Thanks and best regards.

The layout image is as follows, and the product was damaged during normal operation。We have used approximately 2,000 of these components, and 3 of them have failed

The voltage of the negative overshoot we measured is close to -2V. It seems that the negative overshoot is a bit large. Could a large negative overshoot cause the MOSFET to burn out? What could cause the negative overshoot to be large?

Hi WJZ

Sorry that the layout is not clear. Can you attach the layout image of each layer?

The voltage of the negative overshoot we measured is close to -2V. ---please use small probe loop and full-bandwidth and zoom in to measure.

Thanks and best regards.

Hi Gui He

TOP layer

GND

Analog

PWR

Digital

Bottom

Hi Gui He

Use a small probe loop to test the following two pins，The waveform is amplified as shown in the following image。

Thanks and best regards.

Hi WJZ

I will check this early tomorrow.

Thanks and best regards.

Hi WJZ

The layout can be optimized as stated in the 10.1 Layout Guidelines in the TPS54336A datasheet:

Use a separate ground trace to connect the feedback, compensation, UVLO, and RT (SS for TPS54336A) returns. Connect this ground trace to the main power ground at a single point to minimize circulating currents.

The SW waveform should be ok. The negative pulse can be caused by the voltage drop on the parasitic inductance of the bonding wire during fast switching .

Thanks and best regards.

Thank you so much for your help