TPS2493EVM-004: TPS2493 Hot Swap Evaluation Board Mosfet start smoking during the load conditions.

Kishan Patel2

Part Number: TPS2493EVM-004
Other Parts Discussed in Thread: LM5069, TPS2493, CSD19536KTT

I am having trouble with this evaluation board during high load conditions. Or application input is 42V DC and the input source can detect shot if startup current reaching near 32 Amps. To avoid that we would like to use this as an Inrush limiter. Our total output capacitance is 1067 uF and loads current is about 30 Amps. To increase the default sense current limit I changed R15 to 10ohms and R16 to 50ohms and R7 to 2mohms. The board is sufficiently able to limit the inrush but Mosfet starts smoking when load source about 30Amps also I noticed that Mosfet temperature is getting very high above 100C.

The other solution we tried is to use 3 parallel IRFH7085PbF power MOSFET on a new board with 1K resistor on the Gate and we are experiencing the problem as Mosfet in the middle starts getting hot and smoking at load condition.

Second Setup:

Please advise testing anything differently.

Thanks.

over 4 years ago

0 Rakesh over 4 years ago

TI__Guru* 95671 points

Hi Kishan,

Welcome to E2E!

Looks like the MOSFET IRFH7085PbF is not strong enough to handle the stress. Please fill up the design calculator and share it with me for review. The design calculator is available at http://www.ti.com/product/TPS2493/toolssoftware

The following videos help you on how to use the design calculator.

https://training.ti.com/node/1133677

https://training.ti.com/node/1133673

https://training.ti.com/node/1133664

https://training.ti.com/node/1133681

What is your application use case, end product. ? I would suggest to use LM5069 which provides better short circuit response over TPS2493

Best Regards, Rakesh

0 Rakesh over 4 years ago in reply to Rakesh

TI__Guru* 95671 points

Hi Kishan,

Any updates ?

Best Regards, Rakesh

0 Rakesh over 4 years ago in reply to Rakesh

TI__Guru* 95671 points

Hi Kishan,

I am closing this thread. Please feel free to reopen as soon as you get design sheet / test results.

Best regards, Rakesh

0 Kishan Patel2 over 4 years ago in reply to Rakesh

Prodigy 30 points

Hi Rakesh,
Sorry for the delayed response. I tried to fill the design calculator and having trouble with Mosfet Selection. Can you look for the value of R3 and R4. The application is to limit the inrush current to the power supply capacitance. We want to control the current to 30Amps for a total 500uF capacitance. Please suggest any better solution I should try. Apparently seems that Mosfet that I am using might not able to supply enough current.
Also currently we are not planning to use Heat Sinks.

Attaching the calculated sheet.

Let me know if you need any more information.

1220.TPS249x_8x_Design_Calculator_REV_B_Filled.xlsx