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LM27403: LM27403 top side temperature coefficient

Rock Shao
Expert 2895 points
Part Number: LM27403

Hi Team,

At present, customers use this product for low voltage and high current applications, but this product will be very close to the fixture. Since IC is a heating element, customers will worry about the accuracy of the fixture. I only see the θJCtop parameter in SPEC, but it cannot be Converted to the temperature coefficient, so I want to know the temperature coefficient of the top surface. Thanks.

Regards

Rock

  • 0
    TI__Guru 52115 points

     

    I am not sure what you mean by converting the thermal resistance (degrees C / Watt) to a temperature coefficient of the top-surface of the LM27403

    Are you trying to calculate how much heat will transfer between the top surface of the IC the fixture?

    If that is what you are looking for, it will depend heavily on the interface material between the IC's top surface and the fixture's surface.

    Is there a gap-fill material to conduct the heat, or is the heat moving through convection from the top of the package into the air, and then from the air to the fixture?

  • 0 in reply to Peter James Miller
    Expert 2895 points

    Hi,

    This is a parameter required for thermal simulation software settings.
    Thermal resistance is mentioned in the specification. Is there a way to calculate the thermal conductivity from this part?

  • 0 in reply to Rock Shao
    TI__Guru 52115 points

    Thermal Conductivity (K) is a material property.  It is the inverse of thermal resistance.

    Theta = (L x W) / (H x K)

    The LM27403 is 4mm x 4mm x 0.8mm high, if we estimate the  heat source is about half-way up the part that's (0.004m x 0.004m) / (0.0004m x 31 K/W) 

    K =  0.0013 W-m/K  (Or 1.3 W-mm/K if you want the unit in Watt-millimeters per degree Kelvin)