• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 381 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.

TPS7A8300: Thermal resistance between LP5922

Toshihiro Watanabe
Genius 10235 points
Part Number: TPS7A8300
Other Parts Discussed in Thread: LP5922

Hello,

The customer compares RΘJA between TPS7A8300(35.4C/W) and LP5922(49.5C/W).

Is this reason of difference mainly due to die size?

When TPS7A8300 uses, the thermal performance will be better if thermal ground is larger than JEDEC condition. Is my understanding correct?

Best regards,

Toshihiro Watanabe

  • 0
    TI__Guru 55940 points
    Hi Toshihiro,

    There are many factors that influence the thermal performance of a device. These include package size, size of a thermal pad, die size, die location and orientation in the package, mold compound, and more. The die size and thermal pad size are going to be two of the biggest contributors to thermal performance.

    The Thermal Information table is populated with metrics modeled on a JEDEC Hi-K board which provides a standardized way to provide thermal metrics; however, it is not optimized for thermal performance. The primary heatsink for TPS7A8300 is the GND plane; therefore, maximizing the GND copper connected to the LDO thermal pad will yield the best thermal performance for your application.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    TI__Genius 10235 points
    Hello Ryan-san,
    Is themal pad is connected to ground when RΘJA measurement? I am not sure this means actual thermal performance is better or not if thermal pad connected to ground.
    If we can't rely on RΘJA value, how do we estimate the junction temperature in design phase?
    Best regards,
    Toshihiro Watanabe
  • 0 in reply to Toshihiro Watanabe
    TI__Guru 55940 points
    Hi Toshihiro,

    Yes the thermal pad is connected to GND in the thermal models per JEDEC specifications. Please refer to the following Application Report which describes the test method we use: www.ti.com/.../spra953c.pdf

    The thermal pad should be connected to GND as it is the primary heatsink for the LDO. If the thermal pad is not connected, your thermal performance will be degraded.

    Very Respectfully,
    Ryan