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WEBENCH® Tools/TPS62180: Different theta ja values in datasheet and webench power designer

vishak udayakumar
Prodigy 120 points
Part Number: TPS62180

Tool/software: WEBENCH® Design Tools

Hi,

In the datasheet of TPS62180, theta ja value is mentioned as 61.5 degC/W where as in Webench power designer, the corresponding value is 22.5 degC/W. Which value is correct ?

Which value shall i choose for the analysis ?

Thanks and Regards,

Vishak

  • 0
    TI__Mastermind 26800 points
    Hi Vishak,

    The tool often uses an effective thetaja value that closely represents the EVM board for that device and it usually is a strong function of that EVM board design and layout. I am trying to find out more the specifics of this value for TPS62180 and will let you know once I have an update.

    Regards,
    Amod
  • 0 in reply to Amod Vaze
    TI__Mastermind 26800 points

    Hi Vishak,

    I verified with the expert on this device and the effective thetaJA should actually be close to 32C/W for the EVM of TPS62180. We will update the 22.5C/W to 32C/W in the tool. For now, to get an estimate of the IC Tj, please use IC Tj = IC Pd * 32 + Ta. IC Pd is an operating value that is reported in the tool. And, Ta is the ambient temperature.

    So, as an example, for 2W of IC Pd, with 25C Ta, IC Tj = 2 * 32 + 25 = 89C


    Regards,

    Amod