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TPS2553D: Junction Temperature

Philip
Expert 1510 points
Part Number: TPS2553D

Hi,

I have a question on TPS2553DDBVR Operating Junction Temperature.

Under Item 7.3 Recommended Operating Conditions spec, Tj max is 105degC for Iout=1.5A.

Under item 7.5 Electrical Characteristic, Thermal shutdown will occur at 135degC.

May I know what are the differences between these two items spec?

Does it mean for Iout=1.5A, the junction temperature measured/calculated cannot exceed 105degC?

What would happen to the device if Tj is more than 105degC? Operation will be disabled? And any tolerance of 105+- ?degC if the device hits max Tj before it disabled?

And per understanding, thermal shutdown will only occur at 135degC, right?

Please do kindly help to advise, thanks.

Best Regards,

Philip

  • 0
    TI__Expert 8980 points
    Hi, Philip,

    Thanks for your question. I will discuss with other engineers and reply you tomorrow.

    Regards,
    Bob
  • 0
    TI__Expert 8980 points
    Hi, Philip,

    From the description of datasheet, for Iout =1.5A, the recommended Tj should be below 105degC. It means if you want a continuous 1.5A output current, TI recommend to keep Tj below 105degC. If Tj is more than 105degC, the part will be still working but the temperature is close to thermal shutdown temperature. If the temperature is above the thermal shutdown temperature, the part will be disable.

    For example, if you want a continuous 1.5A output current. TI recommend you to keep Tj below 105degC to keep the continuous 1.5A output current. If the Ta is high, cause Tj above 105degC, there will be two case:
    Case 1. The part is working on current limit mode(limited current is set at 1.5A), part will output continuous 1.5A until Tj>135degC, the part will thermal shutdown and hiccup.
    Case2. The part is not working on current limit mode, part will output continuous 1.5A until Tj>155degC, the part will thermal shutdown and hiccup.

    With the thermal shutdown protection, our part will keep Tj below 155deg and protect itself from damage.

    Regards,
    Bob
  • 0 in reply to Bob Ma
    Expert 1510 points

    Hi Bob,


    Thank you for your reply.

    If the part Tj is above 105degC at 1.5A continuous current, does that mean the IC can't guarantee the electrical characteristic?

    Is it possible to provide TPS2553D output current vs Tj curve?

    Thanks.

  • 0 in reply to Philip
    TI__Expert 8980 points
    Hi, Philip,

    You are correct, all the electrical characteristics are guaranteed at recommended operating conditions. Functional operation of the device should not be beyond recommended operating conditions.

    Sorry that we don't have the curve. You can calculate it by the formula in datasheet(11.3 Power Dissipation and Junction Temperature).

    Regards,
    Bob
  • 0 in reply to Bob Ma
    Expert 1510 points

    Hi Bob,


    Possible to get your email address as I would like to share with you some measurement data for confirmation?

    Regards,

    Philip

  • 0 in reply to Philip
    TI__Expert 8980 points
    Hi, Philip,

    I am not sure if I can leave my email here. If you are not in a hurry, I will reply you tomorrow. If you are, you can leave your email here, I will send you email tomorrow. Or you give me other option.

    Regards,
    Bob
  • 0 in reply to Bob Ma
    TI__Expert 8980 points
    Hi, Philip,

    Sorry I can't leave my e-mail address here. Can you leave your email or do you have other way to show your data. Maybe you can upload the data on cloud, so that I can download from cloud.

    Regards,
    Bob
  • 0 in reply to Bob Ma
    Expert 1510 points

    Hi Bob,

    Sorry for delayed reply as I am out of office.

    Email: philip.law@marubunarrow-asia.com

    Thanks.