• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 269 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TL2843: TL2843 Thermal Parameter

Lenna Yan
Intellectual 1960 points
Part Number: TL2843

Hi Expert,

I have several questions about the thermal paramaters.

1. In the TL2843 datasheet, it contains the Rja. when using Rja to calculate Tj, ambien temperature Ta need to be tested. Is Ta tested by the thermal imager? 

2. There is only Rja on the datasheet. What about the ΨJT？

3. The case temperature is 106℃ on customer board, if the junction temp is lower than 150℃ . Does it mean the IC is still safe though the Ta may be higher than 85℃?

  • 0
    TI__Genius 13660 points

    Hi Lenna,

    Ta is ambient temperature, it can be measured by temperature detector.
    The Tj of the TL2843 is rated to 150C, The important point is that you do not exceed the 150C limit. If you exceed 150C the reliability of the part will quickly decrease.
    It is suggested to have 20% margin that allows the junction to reach 120C. And the recommended maximum Ta is 85C.
    If you know how much power is the controller consuming at you maximum ambient condition you can calculate the junction temperature by multiplying the power dissipation in the controller by the junction to board thermal impedance which is 44.4C/W for the 8 pin package and 38.1C/W for the 14 pin device.
    An estimation of the chip-junction temperature, Tj, can be obtained from the following equation:
    Tj = Ta + ( RθJA × PD )...
    where: Ta = ambient temperature for the package ( °C )
    RθJA = junction to ambient thermal resistance ( °C / W )
    PD = power dissipation in package (W)

    Junction-to-top ΨJT is 6.6.


    Regards,
    Teng

  • 0 in reply to Teng Feng
    TI__Intellectual 1960 points

    Hi Teng,

    Thanks for your reply. I see the thermal information on TL2843 datasheet. The RθJA is not 44.4C/W for the 8 pin package and 38.1C/W for the 14 pin device. It's 97C/W for 8 pin package and 86C/W for 14 pin package. Could you double check the data?

  • 0 in reply to Lenna Yan
    TI__Genius 13660 points

    Hi Lenna,

    I find the these thermal datas from thermal model request SharePoint, Sorry I mixed two parameters, the RθJA should be 82.1C/W for the 8 pin package and 103.5C/W for the 14 pin device.

    It is very close to the data in the datasheet. You can just use the RθJA in the datasheet. Thank you.—— Teng