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LM137: Thermal Limiting

Steve Widener
Genius 11010 points
Part Number: LM137

Tool/software:

I have a couple of questions regarding your TI Part, LM137H: (NDT, TO package)

1. What is maximum junction temperature where thermal overload protection occurs?   Is it 150 or 165 deg c?

The datasheet indicates power dissipation is internally limited:

2. Do you have any numbers available for Junction to case bottom. Junction to case top is given on data sheet.

We are performing a thermal analysis and wanted to add the WC number.

  • 0
    TI__Genius 15125 points

    Hello,

    Thank you for your questions.

    Thermal overload occurs at 150 C.

    Here are the numbers:

    Result- Theta JA-High K (standard datasheet value)    60.2
    Result-Theta JC, top (standard datasheet value)    21.1
    Result-Theta JB (standard datasheet value)    66.4
    Result- Psi JT (standard datasheet value)    18.6
    Result- Psi JB (standard datasheet value)    50.5
    Result-Theta JC, bottom (standard datasheet value)    9.0

    Best,

    Hannah

  • 0 in reply to Hannah Grace
    TI__Genius 11010 points

    Thanks Hannah -

    The thermal numbers you provided are way different from the current datasheet specs for the LM137H I se on tt.com:

    The NDT package shows 140C/W vs the table you provided showing 60.2 C/W

    Is there an updated datasheet or am I looking at the wrong values?

    Thanks!

    Steve

  • +1 in reply to Steve Widener
    TI__Genius 15125 points

    Hi Steve,

    We currently do not have an updated datasheet with the numbers for the NDT package, therefore a simulation had to be taken previously for another customer. These were the results assuming: 

    1) Through hold mounting on JEDEC 2s2p PCB with no thermal vias

    2) Case top temperature is center of top can surface

    3) Case bottom temperature is center of header base

    I am assuming these numbers are different because the process of thermal modeling has gotten better since 1999 to more accurately show the device's thermals.

    Best,

    Hannah