2N4029 Temperature-Power Derating Curve [2N4033]
PNP Switching Transistor. Package, TO-18 metal Can [TO-39, Surface Mount]
2N4029 Applications; High-speed switching
2N4029 Transistor Temperature Derating Curves
The chart details the maximum allowable power dissipation with increasing ambient temperature for a 2N4029 transistor. Maximum operational power dissipation is achievable at 25C or below. However above 25C the maximum package dissipation for the 2N4029 must be reduce to insure that the devices junction temperature remains constant. Decreasing a components operational limits as temperature is increased is called derating. This graph details a 2N4029 transistor in a TO-18 package [leaded metal can].
Refer to MIL-PRF-19500/512H; Semiconductor Device, Transistor, PNP, Silicon, Switching, Types 2N4029, 2N4033, 2N4033UA, 2N4033UB, [TO-18 metal can package]
2N4029 Maximum Ratings:
Collector Emitter Voltage = 80 volts dc
Collector Base Voltage = 80 volts
Emitter Base Voltage = 5 volts
Power Dissipation 250C = 400mW
Operating Temperature = -65 to +2000C
Design note; at 200C the 2N4029 should be drawing no current.
Storage Temperature = -65 to +2000C
The curves for the 2N4029 show ambient air temperature vs DC maximum power rating. But there are a few things the derating graph does not show. First these curves relate to sea level, just as most datasheet numbers are provided at 25 degrees Centigrade. Second the air temperature is for still air, free moving. So the 2N4029 is on a Printed Wiring Board [PWB] with no fan and there is no enclosure to stop air flow by convection. Third, there are no components nearby that may generate additional heat which would warm-up the 2N4029. Forth, the top most line is the do not exceed curve, for longest component life use one of the lower gray lines to operate on [makes for a better design]. Finally forced air cooling via a fan could be used in the design or attaching a heat sink to the metal can of the 2N4029 would greatly reduce the amount of derating required.
The 2N4029 may also be shown available in a TO-206AA which is one of the newer JEDEC designations, and is being used as the replacement for the old TO-18 packages by some companies. The TO-39 which is used by the 2N4033 transistor may indicate using the TO-205AD package, which is the newer designation for a TO-39 metal can package.
