2N2218 Transistor Derating Curves

2N2218 Temperature-Power Derating Curve
NPN Switching Silicon Transistor. Package types, TO-39, TO-5 metal Can.
2N2218 Applications; General Purpose Amplifier and Switching Transistor

2N2218/2N2219 Temperature-Power Derating Curve
Temperature Derating Curve for 2N2218 Transistor

The graph shows the maximum power dissipation with increasing ambient temperature for a 2N2218 or 2N2219 in either a TO-39 or TO-5 metal can. Maximum operational power dissipation is achievable only at 250C [Still-Air]. However above 25C the maximum package dissipation, or power, must be reduced [per the curve] to insure that the devices junction temperature remains constant. The higher the ambient temperature is increased the lower the allowable DC power dissipation, as depicted in the curves.

Decreasing a devices operational limits as temperature is increased is called derating, in this case derating a devices operational power dissipation vs increasing case temperature. Above room temperature the 2N2218 must be derated by 4.6mW/0C

For best results use the lowest curve in the graph, this will result in the lowest operating junction temperature for the 2N2218. However using the lowest curve may not always be possible, in which case a parallel line nearest the curve would be the next best thing. Never operate the 2N2218 at or above its maximum junction temperature. Also refer to How to Interpret Derating Curves.

Attaching a heat sink to the 2N2218 will allow higher temperature operation with out the need to derate or reduce the power consumption.

Implementing forced air into the 2N2218 will also allow the transistor to operate at higher temperatures with higher power dissipation rates. The derating curve is for Free-Air and does not account for system operation with a fan. However, because the curve implies free-air it also does not account for the 2N2218 placed within an enclosure or chassis which inhibits air flow.

Refer to MIL-PRF-19500/251; Semiconductor Device, Transistor, NPN, Silicon, Switching, Types 2N2218, 2N2218A, 2N2218AL, 2N2219, 2N2219A, and 2N2219AL, JAN qualified, [TO-39, TO-5]. Qualified per MIL-PRF-19500.

2N2218 Maximum Ratings:
Collector Emitter Voltage = 30 volts dc [Vceo]
Collector Base Voltage = 60 volts dc [Vcbo]
Emitter Base Voltage = 5 volts dc [Vebo]
Collector Current = 800mA dc [Ic]
Power Dissipation 250C = 800mW
Gain = 20 minimum [hfe]
Operating Junction Temperature = -65 to +2000C [Tj]
Storage Temperature = -65 to +2000C [Tstg]

Derating Definitions
Ambient temperature. is the air temperature measured below a semiconductor device, in an environment of substantially uniform temperature, cooled only by natural air convection [Free-Air], and not materially affected by reflective and radiant surfaces.
Temperature coefficient. The ratio of the change in a parameter to the change in temperature.
Thermal resistance. Thermal resistance is the temperature rise, per unit power dissipation, of a junction above the temperature of a stated external reference point under conditions of thermal equilibrium.
Storage temperature. [Tstg] is a temperature at which the device may be stored without any power being applied.
Note; Refer here for all the definitions relating to Temperature and Derating.

TO-5 metal Package
TO-5 metal Can

1-Emitter, 2-Base, 3-Collector

Component Distributors
Transistor Manufacturers
Heat Sink Manufacturers
Fan Manufacturers

Package Characteristics
TO-5 Dimensions
TO-39 Dimensions

Derating Guidelines
Transistor Derating Curves
NPN Transistor Derating Curves
Component Derating

TO-39 metal Package
TO-39 metal Can Package

PC motherboard

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Modified 6/13/15
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