2N2904 Transistor Derating Curves

2N2904 Temperature-Power Derating Curve
PNP General Purpose Transistor. Package, TO-39.
2N2904 Applications; High speed saturated switching

2N2904 power derating curve by temperature
2N2904 Temperature Derating Curve

Thermal Characteristics: [2N2904, 2N2905]
Derate the 2N2904 linearly by 3.43 mW/0C above an ambient temperature of 250C
Derate the 2N2904 linearly by 17.2mW/0C above a case temperature of 250C

Use the Graph to determine how much to derate power [wattage] based on ambient operational temperature. To obtain a higher operational operating temperature apply forced air cooling, the chart covers still air [Fan Manufacturers]. Free air implies that the device is not placed within an enclosure that inhibits air flow and that near by components are not inducing additional heat to the device. The graph shown above covers both the 2N2904 and the 2N2905. The curve for the 2N2904A and 2N2905A is basically the same except for the dashed lined. The line indicating thermal runaway runs out another 10 degrees before dropping, for the 'A' version parts, and terminates at 200 degrees centigrade. Each of the other graph lines are identical between the 'A' version and non-A version, so in order to save space the graph showing the other versions of the part are omitted. Transistor Derating Curves
Temperature derating is a standard design practice for electrical engineers.

Refer to MIL-PRF-19500/290; Semiconductor Transistor, PNP, Switching, Types, 2N2904, 2N2904A, 2N2904AL, 2N2905, 2N2905A, and 2N2905AL, JAN, [TO-39 metal Can package], all of the packages listed use the TO-39.

2N2904 Maximum Ratings:
Collector Emitter Voltage = 40 volts dc [Vceo], 60 volts dc [2N2904A]
Collector Base Voltage = 40 volts dc [Vcbo], 60 volts dc [2N2904A]
Emitter Base Voltage = 5 volts dc [Vebo]
Collector Current = 600mA [Ic]
Power Dissipation 250C = 600mW [Pd]
Operating Junction Temperature = -65 to +2000C [Tj]
Storage Temperature = -65 to +2000C [Tstg]

Heat Sink Manufacturers, Listing of Transistor Manufacturers and BJT vendors

Guideline for ; Derating Electronic Components

Note: The Top curve is thermal runaway and cannot be used as a derate design curve since it exceeds the maximum ratings for the 2N2904. Operating under this curve using these mounting conditions assures the device will not have a thermal runaway. This is the true inverse of the worst case thermal resistance value extrapolated out to the thermal runaway point.
The maximum junction temperature is shown in the black curve is just below the dash line, and may not be used during normal circuit operation. For proper circuit operation use one of the gray curves to insure the 2N2904 does not operate at or near its maximum junction temperature.

The mil spec listed also includes the follow qualified products;

The graph only applies to a TO-39 metal package, but a 2N2904 is also available in a plastic TO-92 package.

Press-on heat sink
Cylindrical Heatsink

TO-39 Package outline and pin-out
TO-39 BJT Package

Lead 1, emitter, lead 2, base, lead 3, collector

PNP General Purpose Transistor
PNP Transistor Derating curves

Refer to the Data Sheet
for additional 2N2904 data.

Larry's Web Page

Electronic Parts and Equipment Distributors Electronic Component Manufacturers OEM Electronic Equipment Manufacturers EDA Software Producers CAD/CAE Software Engineering Standards, EE Publications Interface/Embedded Computer Bus Electronic Engineering Design Data Engineering Reference Information.
DistributorsComponents Equipment Software Standards Buses Design Reference
Modified 1/21/12
© 1998 - 2016 All rights reserved Larry Davis