Dear expert,
My customer is using LM5116 in a 20~40Vin (battery power), 5Vout 2A (load is RF module and etc) buck circuit, fs=250KHz. But now they found 10/1000 ratio board damage issue in their end customer. After checking, Q2 and Q4's gate and drain are all shorted to source, however LM5116 is not damaged.
Please see schematic, PCB, mos datasheet as below. From test file, it seems like that the Vgs and Vds has oscillation. And as load current increasing, the oscillation increased, lead to MOS damage. The current problems are:
1. Whether it is related to the selection of MOS tube, not recommended in the specification, the internal resistance is slightly larger, and the junction capacitance is slightly smaller than the recommended MOS;
2. Whether it is related to the layout, due to space constraints, the MOS tube drive circuit and power circuit are slightly worse;
3. Whether it is related to IC related parameters and whether the selection of related tolerance parameters is reasonable;
4. Whether it is necessary to increase the relevant protection circuit, and whether it is feasible to increase the resistance between the MOS tube drive line and the MOS GS.
Please share your suggestions, thanks.
GPRS01-01V03-20200618-Schematic.pdfGPRS01-01V03-20200618-PCB.pdfAOD291_datasheet.pdf
