38.4.6 Thermal Characteristics

Table 38-9. Thermal Characteristics
SymbolDescriptionTyp.UnitsConditions
θJAThermal Resistance Junction to Ambient (Thermal simulation, no airflow)63.37°C/W14-pin SOIC package (SL)
53.02°C/W20-pin SOIC package (SO)
54.89°C/W20-pin VQFN package (REB)
Note:
  1. Power dissipation is calculated like this:

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

  2. Internal Power Dissipation is calculated as: 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: PDER = PDMAX (TJ-TA)/θJA, where TA = Ambient Temperature, TJ = Junction Temperature.