Tell me about thermal design.

Use general-purpose CMOS logic within the range of power dissipation (P_D) of absolute maximum ratings.

Junction (chip) temperature can be calculated according to the following formulae. In the case of general-purpose CMOS logic, this is used for reliability life.

T_j=θja･P_D+Ta

T_j=θjc･P_D+Tc

θJa=θjc+θca

[Figure: Heat transfer resistance of the package]

List of symbols, units, and items used in the formulae
Symbol	Unit	Item
T_j	°C	Junction (chip) temperature
Tc	°C	Case temperature
Ta	°C	Ambient temperatures
P_D	W	Power dissipation
θja	°C/W	Heat transfer resistance from the case to periphery
θjc	°C/W	Heat transfer resistance from junction to the case
θca	°C/W	Heat transfer resistance from the case to periphery