Power ratings are normally specified at +25oC and must be reduced as the resistor temperature increases, see the derating curve above. A derating chart is often used, with derating starting at 70oC. Since parameters are application dependent, power de-rating curves or charts should be considered general rather than absolute, and only used as a guideline. The safest designs use the largest physical size operating at conservative temperatures and power ratings.
|
|
Wire Wound Temperature |
Metal Film Temperature |
| 100% | 70oC | 70oC |
| 80% | 110oC | 85oC |
| 60% | 150oC | 100oC |
| 40% | 190oC | 120oC |
| 20% | 240oC | 140oC |
| 10% | 260oC | 145oC |
As these are average guide-lines, they may change with other IC packages.
Resistor Network Manufacturers, Resistor Manufacturers, Potentiometer Manufacturers
There are a number of possible IC packages, this is a guide, always check the data sheet for the device being used.
Note the curve shown above relates to MIL-PRF-83401 [Resistor Networks]. The Power Rating for this series is given at an ambient temperature of 700C, so for temperatures below that value the device may be operated above the maximum power rating [above 100 percent]. So at 250C the resistor network may operate at 125% of maximum power.
Derating guidelines for other components; Guideline for Derating Electronic Components
Resistor Network Package Styles, SIP Package Style. Resistor Network Schematics
Key Words: Resistor, Component Derating, reliability, Sizing, Derate, Burned, Network, Curve, Rated Temp, Temperature, Guide, Burning, Guideline, Example, Class, Design.
