• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 742 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS25942A: Inquiry about operating temperature

BJ Han
Expert 2035 points
Part Number: TPS25942A

Dear TI,

As a result of the test applied to the black box under development, it was measured to rise to 93.1 ° C based on T_c in a 55 ° C environment.
Is there any problem when using this?

In the datasheet, R_θJA is lower than R_θJCtop as shown below.
I know that it is generally reversed, but please refer to the picture below and ask for confirmation.

  • 0
    TI__Guru** 105361 points
    Hi BJ Han,

    What are your operating conditions? voltage, max load current, max. ambient temp
    For which end equipment you are doing this design? which features of this device are relevant for this design?

    As the device package is small and the device has thermal pad, R_θJA will be always lower than R_θJCtop. The reason is the device transfers most of heat through pad to PCB to ambient. This path offers lower resistance than junction-to-top path.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Expert 2035 points

    Hi Rakesh,
    Thank you for your support.
    Please refer to the answer below.
    1. Input 12V / Output 5.2V / Load 1A / Charge for about 30 seconds / 55°C chamber environment
    2. Black box
    3. linear charge solution for super cap
     => As a result of the test under the above conditions, it was measured to rise to 93.1 ℃ based on T_c in 55 ℃ environment.
    Is there any problem when using this?

  • 0 in reply to BJ Han
    TI__Guru** 105361 points
    Hi BJ Han,

    Are you using TPS25942A device for linear charging a super cap to 5.2V from 12V source?
    If yes, please refer app note www.ti.com/.../slva920.pdf and adjust dvdt cap value to manage the charging current. The device has inbuilt thermal protection, so, I did not see any concern.
    The black box attachment is missing in the post. Can you send it again.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Expert 2035 points

    Hi Rakesh,

    Thank you for your support.

    Yes, that's right. linear charging.

    There is no problem with charging.

    I am wondering if the operating temperature is not a problem with the device.

    I will attach a black box image.

    black box.pdf

  • 0 in reply to BJ Han
    Expert 2035 points
    Hi Rakesh,
    I have additional questions.
    With respect to thermal shutdown,
    Thermal shutdown condition Tj = 160 ° C exceeds Tj (MAX) = 125 ° C,
    Is there any problem with this operation?
  • 0 in reply to BJ Han
    TI__Guru** 105361 points
    Hi BJ Han,

    Thanks for the details.

    After every thermal shutdown, the device waits till the junction temperature falls by 12C from max i.e., TJ < [T(TSD) – 12°C] and has retry delay of 128ms. This allows the device to cool OFF, which helps and keeps the device in maintaining lower average temperature. So, no change in device life is expected.

    Best Regards,
    Rakesh