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Tell me about thermal design.

Ensure that the power dissipation (PD) of a general-purpose CMOS logic IC do not exceed its absolute rating.

Junction (chip) temperature can be calculated as shown below. In the case of general-purpose CMOS logic, it is used as a parameter in calculating service life as part of reliability evaluation.

Tj=θja・PD+Ta

Tj=θjc・PD+Tc

θJa=θjc+θca

[Figure: Heat transfer resistance of the package]

 

List of symbols, units, and items used in the formulae
Symbol Unit Item
Tj °C Junction (chip) temperature
Tc °C Case temperature
Ta °C Ambient temperatures
PD 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
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·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.