Most devices are manufactured in several temperature grades. Broadly accepted grades are:
Commercial: 0 °C to 45 °C Industrial: −20 °C to 85 °C Military: −55 °C to 125 °C
Nevertheless, each manufacturer defines its own temperature grades so designers must pay close attention to actual datasheet specifications. For example, Altera uses five temperature grades for its products:
Commercial: 0 °C to 45 °C Industrial: −20 °C to 85 °C Automotive: −40 °C to 125 °C Extended: −40 °C to 125 °C Military: −55 °C to 125 °C
The use of such grades ensures that a device is suitable for its application, and will withstand the environmental conditions in which it is used. Normal operating temperature ranges are affected by several factors, such as the power dissipation of the device. These factors are used to define a "threshold temperature" of a device, i.e. its maximum normal operating temperature, and a maximum operating temperature beyond which the device will no longer function. Between these two temperatures, the device will operate at a non-peak level.