2N3743 Temperature-Power Derating Chart [2N4930, 2N4931]
PNP Silicon High Voltage Transistor. Package, TO-39 metal Can [Through-Hole].
2N3743 Transistor Operational Power Derating Curve
Use the Graph to determine how much to derate power [wattage] based on the temperature of the heat-sink [Tsink]. Additional Transistor Derating Curves
Temperature derating is a standard design practice for electrical engineers.
Circuit design hint; use short component leads to quickly conduct heat into the printed circuit card and dump heat into the metal pads or copper planes on the PCB.
Refer to MIL-PRF-19500/397; Semiconductor Transistor, PNP, Silicon, Types 2N3743, 2N3743U4, 2N4930, 2N4930U4, 2N4931, and 2N4931U4, [TO-39, U4 surface mount, or Semiconductor-Die]
2N3743 Maximum Operational Ratings:
Collector Emitter Voltage = 300 volts dc
Collector Base Voltage = 300 volts dc
Emitter Base Voltage = 5 volts dc
2N3743 Power Dissipation 250C = 1 Watt
2N3743 Operating Temperature = -65 to +2000C
The heat generated by the 2N3743 must be less than the thermal conductivity from junction-to-air, use a heat sink for a greater power dissipation at a higher temperature. Note the Thermal Resistance Junction to Case Mount is 35C/W [centigrade per wattage].
Listing of Transistor Manufacturers and vendors.
How to Derate; Guideline for Derating Electronic Components
Derating a 2N3743-U4 SMD BJT
The surface mount U4 version will handle a bit more power, but not much. The three operational gray lines shown in the graph above also relate the SMD version. However they start at; 5.5mW, 6.5mW, and 8.5mW and run down to the same temperatures shown above.
Note this version of the 2N3743 my not be in current production
The layout of the semiconductor die is shown for reference.
The dimensions are 0.041 by 0.041 inches.
