39.4.6 Thermal Characteristics

Table 39-9. Thermal Characteristics
Symbol	Description	Typ.	Units	Conditions
θ_JA	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)
T_JMAX	Maximum Junction Temperature	145	°C
Note: Power dissipation is calculated as follows: P_DIS = V_DD × {I_DD - Σ I_OH} + Σ {(V_DD - V_OH) × I_OH} + Σ (V_OI × I_OL) Internal Power Dissipation is calculated as follows: P_INTERNAL = I_DD × V_DD, where I_DD is current to run the chip alone without driving any load on the output pins. Derated Power is calculated as follows: P_DER = PD_MAX (T_J-T_A)/θ_JA, where T_A = Ambient Temperature, T_J = Junction Temperature.

θ_JA

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)

T_JMAX

Maximum Junction Temperature

145

°C

Note:

Power dissipation is calculated as follows:
P_DIS = V_DD × {I_DD - Σ I_OH} + Σ {(V_DD - V_OH) × I_OH} + Σ (V_OI × I_OL)
Internal Power Dissipation is calculated as follows: P_INTERNAL = I_DD × V_DD, where I_DD is current to run the chip alone without driving any load on the output pins.
Derated Power is calculated as follows: P_DER = PD_MAX (T_J-T_A)/θ_JA, where T_A = Ambient Temperature, T_J = Junction Temperature.

AVR32DB28/32/48