37.9 Thermal Specifications

Table 37-9. Thermal Specifications
SymbolDescriptionTyp.UnitConditions
θJAThermal Resistance Junction to Ambient60°C/W28-pin PDIP package (SP)
47°C/W28-pin SOIC package (SO)
67.1°C/W28-pin SSOP package (SS)
36.1°C/W32-pin VQFN package (RXB)
58.8°C/W32-pin TQFP package (PT)
33.7°C/W48-pin VQFN package (6LX)
55.6°C/W48-pin TQFP package (PT)
30.2°C/W64-pin VQFN package (MR)
38.7°C/W64-pin TQFP package (PT)
TJMAXMaximum Junction Temperature150°C
Note:
  1. Power dissipation is calculated as follows:

    PDIS = VDD × {IDD - Σ IOH} + Σ {(VDD - VOH) × IOH} + Σ (VOI × IOL)

  2. Internal Power Dissipation is calculated as follows: PINTERNAL = IDD × VDD, where IDD is current to run the chip alone without driving any load on the output pins.
  3. Derated Power is calculated as follows: PDER = PDMAX (TJ-TA)/θJA, where TA = Ambient Temperature, TJ = Junction Temperature.