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LM7171 | Need Theta JC parameter

Antenna_Head
Genius 11395 points

Team-

We need the theta J,C parameter for the LM7171- the data sheet only specifies theta JA.  Our customer would like to use airflow and perhaps a heat sink to cool the part, so it would be very helpful to have theta JC for thermal modeling.

Thanks, Best, S. Dunbar, AFA Colorado

  • 0
    TI__Genius 13935 points

    Hello,

    Which package are you interested in?  The SOIC package version of that part has not been characterized, but similar products in that package have Theta JC ratings betweeen 40 and 60 Degrees C/ Watt.  I would use 60 Degrees C/ Watt  to be safe.

    Regards,

    Loren

  • 0 in reply to Loren Siebert 1
    TI__Genius 11395 points

    Thanks, I think we're interested in both packages.  The PDIP appears to have better theta-jA than the SOIC.  Do you have an estimate for it's theta-jC?

    Also, there is 500 LFM airflow in this application, so any thoughts on heat sinking strategies for either of these packages?

    Thanks again! Best, Steve

  • 0 in reply to Antenna_Head
    TI__Genius 13935 points

    Hello Steve,

    I can't find any PDIP in the thermal database, but there are MDIP packages that have Theta JA of 20 to 30 Degrees C per watt. 

    With 500 lfpm you can get away with a fairly small heat sink.  Try looking at the ATS 54150K C2 R0

    http://www.digikey.com/product-detail/en/ATS-54150K-C2-R0/ATS1212-ND/1284926

    In my experience the lateral surface area of the heat sink is much more important than the height it is above the chip.  

    Regards,

    Loren