2N2944 BJT
2N2944 Temperature-Power Derating Curve [2N2945, 2N2946]
PNP Low Power Transistor. Package, TO-46 metal Can.
2N2944 common applications; Low-power circuits
Temperature Derating Curve, 2N2944 Transistor
Use the Graph to determine how much to derate power [wattage] based on ambient operational temperature. Transistor Derating Curves
Use the graph to derate the maximum allowable power dissipation of the device with increasing ambient temperature. Maximum operational power dissipation is only achievable at 25C. Note from the graph that at 2000C [ambient air temperature] operational power dissipation goes to zero. The definition for ambient air is lower down the page.
The chart applies to both the 2N2944 through-hole package and a 2N2944 surface mount package. The graph also applies to the operational limits of a 2N2945 and 2N2946 in either a through-hole or surface mount package [designated by a UB suffix].
Refer to MIL-PRF-19500/382; Semiconductor Device Transistor, PNP, Silicon, Low-Power,
Types 2N2944A, 2N2945A, 2N2945AM, and 2N2946A, 2N2944AUB, 2N2945AUB, 2N2945AUBM,
and 2N2946AUB; [TO-46 thru-hole, or UB surface mount package]
Qualified to JAN, JANTX, JANTXV, JANS, JANHC, and JANKC.
Note some data sheets make reference to TO-206 package, specifically a TO-206AB style.
The TO-206 call-out would be the newer package designation from JEDEC.
The TO-46 package designation may be out-dated, and replaced by the TO-206 number.
2N2944 Electrical Maximum Ratings:
Collector Emitter Voltage = 10 volts dc
Collector Base Voltage = 15 volts dc
Emitter Base Voltage = 15 volts dc
Power Dissipation 250C = 400 mWatts [0.4 watts]
Operating Temperature = -65 to +2000C [2N2944 maximum operational temperature]
List of Transistor Vendors, Clip-on Star Heat Sink Manufacturers
How to Derate Electronic Components, PNP Transistor Derating curves
Ambient air temperature: 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; i.e. no near-by components generating heat.
Many other terms, and their definitions, that relate to transistor derating are located on the Transistor Derating page, including links to graphs and other tabulated data..
