electronics-amplifier tutorial

Many parameters contribute to a design's thermal circuit, including the

device's maximum power consumption for the design, the maximum

environment temperature, package characteristics, and airflow at the

device.

Maximum Power Consumption (P)

Use the power calculator values from design simulations in the Altera

Quartus® II software (or the device's power calculator at

http://www.altera.com) to estimate the maximum power consumption

of the device. Once a prototype design is available, measure the actual

power consumption and use this value for thermal calculations.

Maximum Temperature (TJ & TA)

The maximum ambient and junction temperatures are found in the data

sheet for the device under Device Absolute Maximum Rating and the

operating junction temperature is found under Device Recommended

Operating Conditions. The temperature must be kept within the

maximum conditions or damage could occur. The junction temperature

should be kept within the recommended operating conditions to ensure

the device achieves the performance reported by the Quartus II software.

The rate at which heat is conducted

through a material is proportional

to the area normal to the heat flow

and to the temperature gradient

along the heat flow path. For a one

dimensional, steady state heat flow

the rate is expressed by Fourier’s

equation:

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