Operating temperature

An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the maximum operating temperature (or peak operating temperature). Outside this range of safe operating temperatures the device may fail. It is one component of reliability engineering. Similarly, biological systems have a viable temperature range, which might be referred to as an "operating temperature". Most semiconductor devices are manufactured in several temperature grades. Broadly accepted grades are: Commercial: 0 ° to 70 °C Industrial: −40 ° to 85 °C Military: −55 ° to 125 °C Nevertheless, each manufacturer defines its own temperature grades so designers must pay close attention to actual datasheet specifications. For example, Maxim Integrated uses five temperature grades for its products: Full Military: −55 °C to 125 °C Automotive: −40 °C to 125 °C AEC-Q100 Level 2: −40 °C to 105 °C Extended Industrial: −40 °C to 85 °C Industrial: −20 °C to 85 °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. For instance, a resistor may have a threshold temperature of 70 °C and a maximum temperature of 155 °C, between which it exhibits a thermal derating. For electrical devices, the operating temperature may be the junction temperature (TJ) of the semiconductor in the device.