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Original question:

TPS2595: TPS2595 OVC Threshold vs Temperature Graph

TPS2595: About Thermal Pad

Liu Yang
Expert 8715 points
Part Number: TPS2595

Hi Team,

Please help me answer the follow question from my customer, thank you so much.

In case of a stable complete short circuit, it seems to be limited by the current amount lower than the set current limit.
(according the answer of Jul 6, 2018 7:52 AM at e2e.ti.com/.../703544
Therefore, it seems that the thermal shutdown is taking time. Currently, the current limit is about 2A, but it takes 6 minutes from shorting circuit to thermal shutdown. This time is much longer than expected, so we want to take some measures.
In fact, it has been confirmed that the time to thermal shutdown is accelerated by floating the heat dissipation PAD.
Although it is not recommended to completely dissipate the heat dissipation PAD due to the increased risk of device destruction, should the time to thermal shutdown be adjusted by reducing the GND area?
In the first place, it is a problem because the operation from current limit to thermal shutdown is different from the data sheet.
The objective is to shorten the thermal shutdown time when the output is completely short-circuited.
A few seconds is desirable, if not momentarily.
Thank you for your advice.

Best Regards,
Tom Liu

  • 0
    TI__Guru 57737 points

    Hi Tom Liu,

    Yes, during short circuit conditions the current limit is reduced as per the design of the device. 

    The time to Thermal Shutdown is dependent on the RQJA which is a function of layout.

    Floating the Thermal Pad increases the RQJA significantly but as you said it is not a problem for the device as the device can protect itself by the same thermal shutdown feature.

    As you said, reducing the GND plane connected to the thermal Pad can also be done to increase RQJA.

  • 0 in reply to Praveen GD
    TI__Guru 57737 points

    Hi Tom Liu,

    Do you have any other questions ? If not can we close this thread ?