35.9 Thermal Specifications

Table 35-9. Thermal Specifications
Symbol	Description	Typ.	Unit	Conditions
θ_JA	Thermal Resistance Junction to Ambient	72	°C/W	14-pin TSSOP package (ST)
62	°C/W	14-pin SOIC package (SL)
60	°C/W	20-pin SSOP package (SS)
54	°C/W	20-pin VQFN package (2LX)
49	°C/W	28-pin PDIP package (SP)
51	°C/W	28-pin SSOP package (SS)
34	°C/W	28-pin VQFN package (3LW)
31	°C/W	32-pin VQFN package (QZB)
56	°C/W	32-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 is the ambient temperature and T_J is the junction temperature

θ_JA

Thermal Resistance Junction to Ambient

72

°C/W

14-pin TSSOP package (ST)

62

°C/W

14-pin SOIC package (SL)

60

°C/W

20-pin SSOP package (SS)

54

°C/W

20-pin VQFN package (2LX)

49

°C/W

28-pin PDIP package (SP)

51

°C/W

28-pin SSOP package (SS)

34

°C/W

28-pin VQFN package (3LW)

31

°C/W

32-pin VQFN package (QZB)

56

°C/W

32-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 is the ambient temperature and T_J is the junction temperature