2N4237 Transistor Derating Curves

2N4237 Temperature-Power Derating Curve [2N4238, 2N4239]
NPN Low Power Transistor. 6 watts, 40 voltage, in a TO-39 Package.
2N3437 Applications; General Purpose Amplifiers [GP Amps], Power Amps, Power Driver

How to derate a 2N4237 transistor
2N4237 Transistor Temperature-Power Derating Curve

Use the Graph to determine power dissipation based on the 2N4237 operating at the ambient temperature shown. Attaching a heat sink to the metal can will allow the device to operate at a higher temperature with out the need to reduce power consumption. The graph provides maximum power dissipation in still air at the ambient temperature indicated. The circuit should be designed using one of the gray curves for proper thermal operation, and are only provided as examples. The curve at 150 degress C is only shown to indicate the temperature the electrical tests were performed at.
Note; The dashed line is thermal run-away, and the black line just under that is the maximum junction temperature.

Refer to MIL-PRF-19500/581; Semiconductor Device, Transistor, NPN, Silicon, Amplifier Types: 2N4237, 2N4238, AND 2N4239, [TO-39 package description]

2N4237 Maximum Electrical Ratings:
Collector Emitter Voltage = 40 volts dc [Vceo]
Collector Base Voltage = 50 volts dc [Vcbo]
Emitter Base Voltage = 6 volts dc [Vebo]
Power Dissipation = 1 Watt, 250C [Ta, ambient temperature]
Power Dissipation = 6.0 Watt, 250C [Tc, case temperature]
Operating Junction Temperature = -65 to +2000C [Tj]
Storage Temperature = -65 to +2000C [Tstg]
Gain [Hfe] = 30 min to 150 maximum.

Complementary Device; 2N4234 PNP Transistor
Note the 2N4237 is still in production.

2N4238 Maximum Electrical Ratings:
Collector Emitter Voltage = 60 volts dc [Vceo]
Collector Base Voltage = 80 volts dc [Vcbo]

2N4238 Maximum Electrical Ratings:
Collector Emitter Voltage = 80 volts dc [Vceo]
Collector Base Voltage = 100 volts dc [Vcbo]

Internal schematic of a TO-39 metal case
TO-39 metal Can Transistor

Terminal Identification
Pins; 1 Emitter, 2 Base, 3 Collector
Lead 3 is electrically connected to case.

Related Transistor Protection
2N4238 Derating [60V dc]
2N4239 Derating [80V dc]
NPN Transistor Derating
Transistor Derating Curves
Component Derating Guidelines

Component Vendors
Transistor Manufacturers
... Central Semiconductor
... Fairchild Semiconductor
Heat Sink Manufacturers

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Modified 1/21/12
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