Packaging and assembly

Which symbol denotes the thermal resistance from the chip junction to the surrounding air, indicating a package's heat-dissipation performance?

  1. AθJA (Rth(j-a))
  2. BCpk
  3. CFIT
Show answer and explanation

Answer: A. θJA (Rth(j-a))

θJA is the thermal resistance from the chip junction to the ambient air, in °C/W. The smaller the value, the more easily the package releases heat. Multiplying power consumption by θJA gives the rise in junction temperature above ambient.

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