Thermal Characteristics

Table 1. Thermal Characteristics
Symbol Description Typ. Units Conditions
θJA Thermal Resistance Junction to Ambient (Thermal simulation, no airflow) 60 °C/W 28-pin PDIP package (SP)
74 °C/W 28-pin SOIC package (SO)
67 °C/W 28-pin SSOP package (SS)
36 °C/W 32-pin VQFN package (RXB)
59 °C/W 32-pin TQFP package (PT)
34 °C/W 48-pin VQFN package (6LX)
56 °C/W 48-pin TQFP package (PT)
30 °C/W 64-pin VQFN package (MR)
39 °C/W 64-pin TQFP package (PT)
TJMAX Maximum Junction Temperature 145 °C  
  1. 1.Power dissipation is calculated as follows:

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

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