Transistor Derating Recommendations

Transistor Derating Recommendations based on a linear equation.
Unlike the guidelines in this section, Transistor Derating Curves are not provided.

Transistor Failure Rate

These design recommendations are for devices in still air, with no other near-by devices generating heat. So they do not account for a device inclosed in a chassis next to other transistors on the Printed Wiring Board [PWB]. So in the final design these number may not achieve the design goal of keeping the junction temperature under its maximum number [depending on the individual transistor]. As a general guideline use the Derating Factor shown to the left.

2N918, TO-72 metal can
Derate linearly above 25C, 1.14 mW/⁰C

2N918UB, UB SMD package
Derate linearly above 25C, 1.14 mW/⁰C

2N1893, TO-5 metal can
Derate linearly above 25C, 17.2 mW/⁰C

2N2060, TO-77 metal can
Derate linearly above 25C, 12.1 mW/⁰C

2N2369, TO-18 metal can
Derate linearly above 25C, 2.06 mW/⁰C

2N2605, TO-46 metal can
Derate linearly above 25C, 2.28 mW/⁰C

2N2857, TO-72 metal can
Derate linearly above 25C, 1.71 mW/⁰C

2N2905, TO-39 metal can
Derate linearly above 25C, 17.2 mW/⁰C

2N2907, TO-18 metal can
Derate linearly above 25C, 3.08 mW/⁰C

2N2919, TO-78 metal can
Derate linearly above 25C, 7.14 mW/⁰C

2N2920, TO-78 metal can
Derate linearly above 25C, 7.14 mW/⁰C

2N3057, TO-46 metal can
Derate linearly above 25C, 10.3 mW/⁰C

2N3227, TO-18 metal can
Derate linearly above 25C, 2.06 mW/⁰C

2N3486, PNP, TO-46 metal can
Derate linearly above 25C, 11.43 mW/⁰C

2N3499, NPN, TO-39 metal can
Derate linearly above 25C, 5.71 mW/⁰C

2N3500, NPN, TO-39 metal can
Derate linearly above 25C, 5.71 mW/⁰C

2N3501, NPN, TO-39 package
Derate linearly above 25C, 5.71 mW/⁰C

2N3506A, NPN, TO-39 package
Derate linearly above 25C, 28.6 mW/⁰C

2N3507, NPN, TO-39 package
Derate linearly above 25C, 5.71 mW/⁰C

2N3700, NPN, TO-18 package
Derate linearly above 25C, 3.08 mW/⁰C

2N3735, TO-39 metal Can
Derate linearly above 25C, 16.6 mW/C

2N3737, TO-46 metal Can
Derate linearly above 25C, 11.3 mW/C

2N3810, TO-78 metal Can
Derate linearly above 25C, 3.43 mW/C

2N3811, TO-78 metal Can
Derate linearly above 25C, 3.43 mW/C

2N3866, TO-39 metal Can
Derate linearly above 25C, 16.6 mW/C

2N3904, TO-92, SOT-23, SOT-223
Derate linearly above 25C, 5 mW/C

2N3960, TO-18 metal Can
Derate linearly above 25C, 2.3 mW/C

2N3996, Stud
Derate linearly above 25C, 11.4 mW/C

2N3997, Stud
Derate linearly above 25C, 11.4 mW/C

2N3998, Stud
Derate linearly above 25C, 11.4 mW/C

2N3999, Stud
Derate linearly above 25C, 11.4 mW/C

2N4029, TO-18 metal Can
Derate linearly above 37.5C, 3.08 mW/C

2N4449, TBD package
Derate linearly 6.85 mW/⁰C above TC = +25⁰C

2N6674, 2N6675 TO-3 package
Derate linearly 34.2 mW/⁰C above TC = +25⁰C

2N6689, 2N6690 TO-61 package
Derate linearly 17.1 mW/⁰C above TC = +25⁰C

2N7508U3, TO-276AA package
Derate linearly 0.6 mW/⁰C above TC = +25⁰C

2N7580T3, TO-254AA package
2N7582T3, TO-254AA package
2N7584T3, TO-254AA package
2N7585T3, TO-254AA package
Derate linearly 1.67 W/⁰C above TC = +25⁰C

2N7625T3, TO-257AA package
Derate linearly 0.6 mW/⁰C above TC = +25⁰C

Attach a Heat Sink to the components tab for higher temperature operation.
Otherwise follow the recommendations in the curve or consult the data sheet.

For a general Rule-of-Thumb recommendation follow this Dearating Factor
Transistor Stress Ratio = Operating Power / Rated Power = 75%