37.9 Thermal Specifications

Table 37-9. 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)
30.2	°C/W	64-pin VQFN package (MR)
38.7	°C/W	64-pin TQFP package (PT)
T_JMAX	Maximum Junction Temperature			Refer to the Absolute Maximum Ratings section
Note: Power dissipation is calculated as 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 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 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

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)

30.2

°C/W

64-pin VQFN package (MR)

38.7

°C/W

64-pin TQFP package (PT)

T_JMAX

Maximum Junction Temperature

Refer to the Absolute Maximum Ratings section

Note:

Power dissipation is calculated as 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 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 P_DER = PD_MAX (T_J-T_A)/θ_JA, where T_A = Ambient Temperature, T_J = Junction Temperature.