35.9 Thermal Specifications

Table 35-9. Thermal Specifications
Symbol	Description	Typ.	Unit	Conditions
θ_JA	Thermal Resistance Junction to Ambient	60	°C/W	28-pin PDIP package (SP)
		47	°C/W	28-pin SOIC package (SO)
		67.1	°C/W	28-pin SSOP package (SS)
		36.1	°C/W	32-pin VQFN package (RXB)
		58.8	°C/W	32-pin TQFP package (PT)
		33.7	°C/W	48-pin VQFN package (6LX)
		55.6	°C/W	48-pin TQFP package (PT)
Note: Calculate power dissipation as follows: P_DIS = V_DD × {I_DD - Σ I_OH} + Σ {(V_DD - V_OH) × I_OH} + Σ (V_OI × I_OL) Calculate Internal Power Dissipation as follows: P_INTERNAL = I_DD × V_DD, where I_DD is the current running the chip alone without driving any load on the output pins. Calculate Derated Power as follows: P_DER = PD_MAX (T_J-T_A)/θ_JA, where T_A = Ambient Temperature, T_J = Junction Temperature.